WO2000007115A1 - Method and system for controlling access to computer conferences using relief objects - Google Patents

Abstract

A system (500) and method for using a relief object image generator (514) for cursor control, computer access control, and operational parameter control is disclosed. The system (500) includes a relief object generator (514), a sensor array, an image processor, and a memory. The relief object image generator (514) generates images of relief objects, such as fingerprints, brought in proximity of the exposed surface of the image generator (514). The image processor receives the image from the sensor array, processes the image, and compares the resulting descriptive information (582) to stored information (518) corresponding to authorized users (504). If a match is found, the user is granted access to the computer. The image processor may also process the image to determine image movement or the image's presence and absence of the image is used to generate highlight and select signals. These signals conform to those generated by known mouse devices so the system of the present invention can replace a position variable device in the keyboard of a laptop or other portable computer without sacrificing functionality for the system. Other uses of the system (500) disclosed herein includes control of operational parameter for a device such as brightness and contrast for a monitor and the transmission of relief object images to remote sites for authentication of a user (504).

Description

METHOD AND SYSTEM FOR CONTROLLING ACCESS TO COMPUTER CONFERENCES USING RELIEF OBJECTS

This application claims the benefit of U.S. Application No. 09/066,624 filed April 24,

1998 which claims the benefit of U.S. Provisional Application No. 60/066,814 filed on

November 26, 1997.

Field of the Invention

This invention relates to relief object image generators, and more particularly, to use of

relief object image generators with computer systems.

Packground pf the Invention

Systems for generating images of relief objects are known. Relief objects are objects

having a surface with features typically formed by areas and sections lying both within and

outside a single two-dimensional geometric plane. A common relief object imaged by known

technology is the surface of the human finger which contains ridges and valleys forming a

fingerprint. These known systems include a platen to which a relief object is pressed to expose

the ridges (areas of the fingerprint which contact the platen) and valleys (areas of the fingerprint

which do not contact the platen) of the relief object to imaging equipment. The platen is

illuminated by a light source. In many relief object imaging systems, the light from the light

source is passed through a collimator before it illuminates the platen. The light is typically

coupled through a right-angle prism to the platen at or near an angle corresponding to Total

Internal Reflection (TLR). The frustration of TLR and the resulting absorption of light occurs at

the ridges of the relief object where the relief object actually makes contact with the platen, thereby creating dark areas corresponding to these ridges. TLR remains undisturbed at the valleys

of the relief object where no physical contact with the relief object occurs so illuminated patterns

corresponding to the valleys are generated. Thus, light from the light source is modulated by the

structural features of the relief object pressed against the platen and this modulated light is

transmitted through the platen to an optical system. The optical system is usually comprised of

lenses and other optical treating components. The optically treated, modulated light then

impinges on a sensor array which converts the optical energy into electrical energy. The

intensity at each element of the sensor array is typically converted to a digital value and the

values for the array elements may then be processed by a computer for classification or

verification of the relief object.

These known relief object imaging systems have a number of disadvantages. For one,

each requires a light generating source which must be located at a distance from the platen so that

a substantial portion of the platen surface is illuminated by the light source. Additionally, the

optically treating elements are typically placed at a distance and angle from the platen to receive

the reflected light from the platen. To optimize the benefits of the optical element processing,

the optical treating elements must be located at distances from the platen where light rays

converge or other known optical physical phenomena occur. Thus, the geometry of known relief

object imaging systems impose size constraints which limit the applications for known relief

object imaging systems.

Another disadvantage of known imaging systems are distortions of the reflected image.

For example, the platen and sensor array in a typical relief object imaging system are tilted to

maintain good focus while also maintaining platen illumination near the TIR angle. This tilting

causes a type of distortion known as a keystone distortion, which is an apparent shortening of one side of the image due to an asymmetrical magnification factor imposed by this tilt angle.

The resulting optical aberration causes the relief object image generator to create a trapezoidal

image from a square object. Frequently, this distortion is reduced by interposing optical

elements between the sensor array and the platen. However, the interposing of additional optical

treating elements exacerbates the geometric constraints for the system and further impacts the

applications in which the system may be used.

Known relief object image generating systems are also sensitive to ambient light entering

the platen from the surface on which the relief object is placed. Additionally, the presence of an

excessive amount of moisture or oil on the relief object alters the modulation of the light by the

relief object and may further degrade the image of the relief object in such systems. Likewise, an

exaggerated absence of moisture and other fluids in a relief object, such as a fingerprint, may

also alter the light modulation produced by the relief object and degrade the image of the relief

object. Also, systems which are engineered to address image degradation caused by excessive

moisture may not adequately correct degradation caused by excessively dry relief objects and

vice versa.

Other known relief object image generators which are not based on light emission

principles replicate fingerprint images using direct capacitive coupling between the finger and an

electrical sensor. These devices typically suffer from sensitivity to electrostatic discharge

environments and can typically be severely damaged through abrasion. The greatest

disadvantage with these devices is the cost of these relief object image generators which render

the wide scale integration of these devices into computer systems economically impractical.

Computer security is an increasingly important concern as computers become smaller and

personal computer inter-connectivity proliferates. The mobility and enhanced capabilities of computers provide computational resources at sophisticated levels as well as at previously

unknown locations and situations. These advancements make unauthorized computer access

more likely because effective physical control is more difficult to exercise over small portable

computers than stationary computers and open networks like the Internet make logical access to

computers easier. One way to frustrate the purpose of computer thieves is to deny them, or the

persons to whom they sell the computers, the ability to use the computer. Most computer access

control systems use a password or other secret tokens that an authorized user enters to activate a

computer system. However, most computer thieves can disable password protection or similar

security access features so the computer may be used by someone other than an authorized

person. While there are known systems for limiting access to valuable resources by identifying

authorized persons with fingerprint imaging systems, known relief object image generators do

not possess physical geometrical dimensions which render them compatible with laptop

computers and the like for reasons discussed above.

Associated with the increasing need to enhance computer access security is the need to

accomplish much of the typical computer/user interface functionality in a more compact, cost

effective and ergonomically efficient manner. That is, as the footprint of portable computers

decreases, the area available for the keyboard, function keys and cursor control devices also

decreases. Thus, a need is arising for a cursor controller that requires less area of a keyboard

than known touchpads or that can be integrated with other functional components of a user's

keyboard.

On-line conferences conducted over open networks are well known. On-line conferences

are typically supported by a host server that couples two or more users together in a

communication process. As one user types a message, it is displayed on the terminals of the other conference participants who are also coupled to the server in the same communication

session. As a consequence, the participants in the conference are able to interact in a manner that

appears to mimic conversation. Hence, a more commonly used term to describe such

conferences is "chat rooms." The servers that host communication sessions for conferences may

be associated with an Internet service provider (ISP) or may be operated by some party having an

interest in facilitating discussions on a particular subject matter. The ISP or third party may

permit subscribers only to join conferences hosted at the server and some may require payment

of a subscription fee before permitting a user to join a conference. Most on-line conference

sponsors which have a subscriber base typically require a subscriber to submit identification so

the server can verify the user's authorization to join a conference. A typical form for verifying

user access includes submission of a personal identification number (PLN). A well recognized

problem with PLNs is that unauthorized users may obtain access to a person's PIN or may capture

a transmission of a PLN to a server because the PLN is transmitted over an open network. While

the PLN may be encrypted, the encrypted PLN may still be captured and the encryption method

broken to discover the PLN. Compromising the security of a conference is of particular concern

when the conference is for discussion between children. Ln this case, pedophiles may

masquerade as other children in the conference, if a authorized PLN can be located, and use the

conversation to lure a child into a situation that may be harmful. Companies are also concerned

about the identity of users participating in on-line conferences regarding confidential projects of

the business.

What is needed is a method of verifying the identity of each conference participant that

does not require a PIN. What is needed is a method of securing access to a conference for children that

substantially reduces the risk that an adult will masquerade as a child user in the conference.

Summary of the Invention

The above identified limitations and disadvantages of previously known computer access

control devices are overcome by a system made in accordance with the principles of the present

invention. A computer access control system made in accordance with the principles of the

present invention includes a relief object generator which is comprised of a single electrode

electroluminescent device coupled to an alternating current source to generate an image

corresponding to a relief object placed against the relief object image generator, a sensor array

for receiving the generated image and converting the image to electrical signals, a memory for

storing image data corresponding to a relief object associated with an authorized user, and an

image processor for generating image data corresponding to the electrical signals received from

the sensor array and for comparing the stored image data to the generated image data, the image

processor generating an access granted signal in response to the stored image corresponding to

the generated image data. Preferably, the image data generated by the processor of the access

control device is descriptive information that corresponds to the generated image and the image

data stored in the memory is descriptive information that corresponds to the relief object image

associated with the user.

A computer control device made in accordance with the principles of the present

invention includes a relief object image generator coupled to a computer for user access, the

relief object image generator for generating images of a relief object brought in proximity to the

relief object image generator, a sensor array for receiving the generated images and converting the images to electrical signals corresponding to the received images, and an image processor for

converting the electrical signals received from the sensor array to computer control signals. A

computer control device made in accordance with the principles of the present invention may

control a computer function by processing relief object image changes to generate function select

or activation signals. For example, the image processor may generate a select signal in response

to the image processor detecting the presence and absence of a relief object image generated by

the relief object image generator. As another example, the image processor may control a "click"

operation by generating a "click" function control signal in response to the image processor

detecting a presence, absence, and renewed presence of a relief object image generated by the

relief object image generator. To control operational parameters for a computer system, the

image processor of the computer control device of the present invention, may generate an

operational parameter control signal in response to movement of a relief object image generated

by the relief object image generator. By adding memory to the computer control device and

storing information corresponding to authorized individuals, the computer control device may

also be used as a computer access control device as described above.

The relief object image generator used in the computer access control device of the

present invention has a reduced geometry and the ability to incorporate other functions required

for computer operation by using a single electrode electroluminescent device and an electrical

current source. The electroluminescent device may be an inorganic or organic

electroluminescent device. With an electroluminescent device, the electrical current source has

one lead coupled to the single electrode of the electroluminescent device and a second lead

coupled to a relief object in proximity to the electroluminescent device. This electroluminescent device provides current to the relief object and the current is strongly coupled from the relief

object to the single electrode electroluminescent device by ridges of the relief object while the

current is weakly coupled to the electroluminescent device by the valleys of the relief object.

Those areas of the electroluminescent device which are strongly coupled to the current from the

relief object generate light which is more intense than the areas of the electroluminescent device

which are weakly coupled to the current from the relief object. The light generated by the

electroluminescent device in correspondence with the valleys and ridges of the relief object

forms an optical image of the relief object. The electrodes in known electroluminescent devices

are typically planar and are used to provide a light field that corresponds to the aligned areas of

the electrodes. By fabricating the electroluminescent device with a single electrode and coupling

the current source to a relief object held against the single electrode electroluminescent device,

the amount of current coupled to different areas of the electroluminescent device varies in

correspondence with the valleys and ridges of the relief object and generates an image of the

relief object.

An organic single electrode electroluminescent device creates an image of a relief object

as described above. However, as these devices typically require lower voltage but higher current

than that required for inorganic electroluminescent devices, they may include a pressure- variable

impedance layer and a flexible conductive layer. In this implementation, the second lead of the

current source is connected to the flexible conductive layer overlaying the impedance layer such

that the pressure generated by the ridges of the relief object pressing against the flexible

conductive layer form current paths in the impedance layer and, correspondingly, an image of

those ridges. Preferably, direct current (DC) sources are used with organic electroluminescent

devices and alternating current (AC) sources are used with inorganic electroluminescent devices. The optical image generated by the system of the present invention may be processed by

optical elements and provided to a sensor array. Typically, the optical elements include

reduction lenses which reduce the size of the image and, correspondingly, the size of the sensor

array used to convert the image to electrical signals. Sensor arrays used in these embodiments of

the present invention may be integrated circuits or the like. Using reduction lenses to reduce the

size of the image, and correspondingly, the integrated circuit sensor, saves cost as the integrated

circuit is made of silicon which has a cost directly proportional to the physical surface area of the

integrated circuit. In another embodiment of the present invention, a one-to-one sensor array is

located proximate to the single electrode electroluminescent device. The one-to-one sensor array

has a length and width which is approximately the same as the electroluminescent device. The

one-to-one sensor array may be made of a semiconductor material on an insulating substrate,

such as amorphous silicon on glass. Because the sensor array is proximate to the

electroluminescent device, the thickness of the computer access control device of the present

invention is substantially smaller than previously known systems that require an optical element

to focus light reflected from a platen onto a sensor array. Additionally, the sensor array and

electroluminescent device are substantially orthogonal to the path of the light generated by the

electroluminescent device. As a result, distortion caused by angular placement of the platen and

sensor array in previously known systems is essentially eliminated. The ability of the single

electrode elecfroluminescent device to generate light allows the computer access control device

of the present invention to operate without an external light source. This further contributes to

the reduced size and complexity of the access control device of the present invention.

In a system of the present invention which uses an inorganic single electrode

elecfroluminescent device, the electroluminescent device includes a transparent electrode layer, a dielectric layer, a light emitting layer which is interposed between a first surface of the

transparent elecfrode layer and a first surface of the dielectric layer, and an alternating current

source which has a first lead coupled to the transparent elecfrode layer and a second lead that is

proximate to a second surface of the dielectric layer. While the dielectric layer may be

translucent, it, preferably, is substantially opaque to attenuate the amount of light transmitted

through the second surface of the dielectric layer that is not generated by the relief object such as

ambient light. When a relief object is placed in contact with the second surface of the dielectric

layer and is coupled to the second lead of the alternating current source, current is strongly

coupled from the ridges of the relief object through the dielectric layer and light emitting layer to

the transparent elecfrode while current is weakly coupled from the valleys of the relief object to

the transparent elecfrode. The light emitting particles in the strongly coupled current path

generate light more intensely than those particles in the weakly coupled current path. While the

term "transparent" is used to describe the elecfrode layer of the electroluminescent devices used

in the systems made in accordance with the principles of the present invention, the reader should

understand that as long as sufficient light is passed by the electrode so a relief object image or

descriptive information about a relief object image can be generated, the electrode is adequately

"transparent." Thus, the term "fransparent" refers to both fransparent and translucent materials as

those terms are typically understood.

A relief object relief generator used in a computer control device made in accordance

with the principles of the present invention does not require an external light source or a

collimator as no light is required for platen illumination. Instead, a relief object causes the single

electrode elecfroluminescent device to generate a self-luminous optical image of the relief object

when the relief object is coupled to the current source and brought in contact with the single electrode electroluminescent device. Because the light is generated by the structure and not

illuminated by a light source, the sensor may be placed directly opposite the transparent electrode

of the electroluminescent device. No intervening optical elements are required for treating the

light to reduce distortion caused by the angles at which the light source, platen and sensor array

are located in previously known systems. As a result, the relief object imaging system is much

more compact and may be used in computer systems more easily, economically and efficiently

than previously known imaging systems. For example, one embodiment of the present invention

may be located on a keyboard of a laptop computer to generate an image of a fingerprint which

may be processed to generate descriptive information that is distinctive for the fingerprint. The

information may be the image itself or a set of algorithmically derived templates which map

repeatable fingerprint characteristics that are unique to the individual to which the fingerprint

belongs. The descriptive information is compared to stored fingerprint descriptive information to

provide access to the computer or converted to digital information and transmitted to another

computer for access to another computer system to verify a financial transaction over a network.

Thus, the computer access control device of the present invention may be used to generate

descriptive data about a relief object at a remote site or to generate an access granted signal based

on a local comparison of the descriptive data with stored data. Either the descriptive data or the

access granted signal may be transmitted to another computer coupled to an open network. The

second computer may use the transmitted descriptive data to verify that the user associated with

the relief object at the remote site is authorized to access the second computer. Consequently,

security for logical access to computers coupled to an open network is enhanced.

Another inorganic single electrode elecfroluminescent device that may be used with

systems made in accordance with the principles of the present invention includes a transparent electrode layer, a light emitting layer having an exposed outer surface, and an alternating current

source which has a first lead coupled to the transparent electrode layer and a second lead that is

proximate to the exposed surface of the light emitting layer. When a relief object is placed in

contact with the exposed surface of the light emitting layer and is coupled to the second lead of

the alternating current source, current is strongly coupled from the ridges of the relief object

through the light emitting layer to the transparent electrode while current is weakly coupled from

the valleys of the relief object to the transparent elecfrode. The light emitting particles in the

strongly coupled current path generate light more intensely than those particles in the weakly

coupled current path. The capacitive effect provided by the dielectric layer in the embodiment

discussed above is provided by the capacitance of the relief object especially when the relief

object is a person's finger.

The light emitting layer of the inorganic type of electroluminescent device may include

phosphor particles which may be a coating applied and adhered to the first surface of the

transparent electrode layer using a binding agent. Alternatively, the light emitting particles may

be dispersed throughout a dielectric layer of an inorganic electroluminescent device. In this type

of inorganic electroluminescent device, the light emitting particles may also be phosphor

particles and the phosphor particles may be encapsulated within a protective dielectric layer to

prevent moisture from degrading the phosphor. Preferably, the transparent elecfrode layer of an

inorganic electroluminescent device is comprised of indium tin oxide (ITO) or a zinc

oxide:aluminum (ZnO: AT) composite; the phosphor is preferably zinc sulfidexopper (ZnS:Cu) or

it may be zinc sulfide:manganese (ZnS:Mn); and the dielectric layer may be barium titanate

(BaTiO₃). The light emitting layer of this type of inorganic elecfroluminescent device may also

include reflective or refractive particles which cause the light generated by the phosphor to become more directional and, therefore, more concentrated in the direction of the sensor.

Empirical measurements indicate that both the frequency and the waveform of the alternating

current source may be adjusted to control the contrast between the light generated by the ridges

and valleys of the relief object. By adjusting the voltage amplitude of the alternating current

source, the average light intensity generated by the phosphors may be varied. Thus, the systems

of the present invention using this type of inorganic elecfroluminescent device provide contrast

and intensity control of the light image generated by the relief object image generator.

Another electroluminescent device that may be used with the systems of the present

invention includes a pressure- variable impedance layer that covers the dielectric layer, a flexible

elecfrode that covers the variable impedance layer and the second lead from the alternating

current source is coupled to the flexible electrode. The variable impedance layer is comprised of

conductive and/or capacitive particles dispersed through a non-conducting compressible

polymer. Where the ridges of a relief object contact the flexible electrode and generate localized

pressure, a conductive path through the impedance layer is formed by bringing

conductive/capacitive particles into proximity with one another. Those areas of the flexible

electrode proximate and aligned with the valleys of the relief object do not generate significant

localized pressure which compresses the conductive/capacitive particles. Thus, the particles

remain separated and less current is passed through those portions of the layer. Accordingly, the

localized pressure caused by pressing the ridges of the relief object against the flexible electrode

provide more current from the alternating current source to the fransparent elecfrode through the

dielectric and light emitting layers. Again, the magnitude of the current passing though the light

emitting particles determines the intensity of the light for the optical image of the valleys and

ridges of the relief object. Systems using the electroluminescent devices with a pressure-variable impedance layer

do not couple current from the alternating current source to the relief object. Instead, the relief

object forms conductive/capacitive paths in the variable impedance layer for the current supplied

from the flexible elecfrode. Thus, these systems insulate the relief object from the alternating

current. This is especially advantageous for systems incorporating relief object imaging systems

that are used in countries having regulations regarding the amount of current to which a person

can be exposed. Because pressure from the structure of the relief object generates the

conductive/capacitive paths through the variable impedance layer, excessive moisture or dryness

does not degrade image contrast as happens in systems where the platen of a relief object image

generator must be illuminated.

Systems made in accordance with the principles of the present invention may include an

organic electroluminescent device. The structure of the organic elecfroluminescent device may

be comprised of a thin, sublimed molecular film such as tris (8-quinolinolato) aluminum (III),

commonly denoted as Alq or a light-emitting polymer with specialized structures which provide

positive and negative charge carriers having high mobility. Light-emitting polymers include

poly (p-phenylene vinylene) or PPV, soluble polythiophene derivatives, and polyanilene which

may be applied to the specialized structure by known coating techniques such as spin or doctor-

blade coating.

Because organic electroluminescent devices operate at low voltages, the relatively high

self-resistance of common relief objects do not effectively modulate the luminescence generated

by the electroluminescent device. If the relief object to be imaged is not capable of withstanding

a relatively large voltage drop at currents of at least a few milliamperes, an insulating layer is

preferably provided between the relief object and the organic electroluminescent device. Preferably, the insulating layer is a pressure-variable impedance layer such as the one discussed

above. The pressure-variable impedance layer selectively provides an electrical impedance

which varies in correspondence with the ridges and valleys of the relief object contacting the

impedance layer. As a result, the higher level currents may be presented through the lower

impedance paths to the organic electroluminescent device to generate holes and electrons which

recombine to produce localized photons. More preferably, the organic elecfroluminescent device

is coated with a pixelated low work function metal such as calcium or aluminum to effect

efficient electron charge injection. Inventive systems which utilize an organic

elecfroluminescent device provide a relief object image generator which may be powered from a

DC current source.

A relief object image generator of the type described above possesses physical

geometrical dimensions, relatively lower costs, and environmental robustness which make it

compatible with portable computers such as laptop computers, desk-top personal computers,

associated peripherals and the like. The relief object image generators discussed above are also

compatible with other applications where personal identification numbers (PLN) and passwords

are currently used and where volumetric constraints have prevented the practical integration of

previously known relief object image generators. Examples of these applications include cellular

telephones, keyless entry devices for all applications requiring physical security (including

buildings, rooms, automobiles, etc.). Another application where the relief object generators

discussed above may be used is a point-of-sale device that verifies a user's identity using

information available from a fixed or portable memory. In this application, fixed memory

applies to the memory physically resident with the relief object image generator. Portable

memory is any information storage media or device which is not physically resident with the relief object image generator but is typically controlled by the user. This includes, but is not

limited to, printed data in the form of symbology, optical laser cards, smart chip cards, passive

and active RF cards and magnetic stripe cards.

In a portable computer, a single electrode electroluminescent device is mounted,

preferably near the keyboard, so a user may place a finger on the surface of the

elecfroluminescent device. The current source and automatic gain control (AGC) are in electrical

connection with the electroluminescent device while the image sensor is located behind and in

the optical path of the elecfroluminescent device. The image generated by the electroluminescent

device is converted by the sensor array to electrical signals and then processed by the computer's

processor or an application specific integrated circuit (ASIC) to generate descriptive information

that is unique to that fingerprint. The processor or ASIC determines whether the resulting set of

fingerprint descriptive information corresponds to one of the sets stored within the computer for

authorized users. If the descriptive information corresponds to one of those stored in the

computer, the computer is activated. Otherwise, access to the computer is denied. Preferably,

the relief object image generator is normally in a "sleep" mode when the computer is off. By

touching the relief object image generator, power is applied to the computer and the

authorization process commences. If authorization is verified, the computer is automatically

initialized with a predetermined set of programs and connections. Likewise, the relief object

generator may be used to obtain an image of a person's finger so it can be processed and the

resulting fingeφrint descriptive information fransmitted to a remote site and used to authenticate

a person from a remote system. For example, an image of a person's fingeφrint may be

obtained, processed and fransmitted to a banking system for access to a person's financial

account or to view real-time images of one's child at a daycare center that can be accessed over an open network such as the Internet. In both the remote authentication and local authentication

applications, the security afforded by the use of the relief object image generators discussed

above may be further enhanced by the employment of an encryption technique for the

transmission of the descriptive information and/or the command signifying a successful match.

This would help to prevent the intentional or unintentional subversion or corruption of that data.

In another application, the relief object image generator is mounted on or near a computer

keyboard, as discussed above, and used to image a person's fingeφrint. This image data may

then be encrypted and sent to a conference host server or the image data may be processed to

generate a set of identifying data for a user. The image data or identifying data set are included

in a user identification message and sent to the conference host server. At the host server, a

database of biometric data corresponding to each authorized user is maintained. The biometric

data may be obtained during a registration process and converted to electronic form for storage at

the host server. The host server receives the user identification message containing the biometric

data identifying the user, compares it to the biometric data for the authorized users stored in the

user database and determines whether the biometric data in the received data message

corresponds to one of the authorized users for the host server. If the user identification data

corresponds to one of the authorized users, the user is coupled to the conference supported by the

host server. Otherwise, the user is denied access to the conference supported at the host server.

While the relief object image generator discussed above may be mounted at any suitable

location on a computer, preferably, it is mounted in a location convenient for user access. In

most portable and desk-top computers, a cursor confrol device such as a mouse, joystick,

direction keys or other variable position/direction indicating device, is placed in such a location. By sizing the relief object image generator so it approximates or is less than that of known cursor control devices, the relief object image generator may be more readily incoφorated into

computers of current design through the physical replacement of these cursor control devices. Of

course, if the relief object image generator physically replaces the cursor control device and all

previous functionality is to be retained, the relief object image generator must be capable of

accomplishing all functions associated with the replaced cursor control device.

In the cursor confrol device of the present invention, an image generated by the single

electrode electroluminescent device of a relief object image generator is detected by light sensing

elements of a sensor array and provided to an image processor. In response to movement of an

object or finger imaged by the relief object image generator, a number of the light sensing

elements may transition from a light detecting state to a no light detected state or vice versa. The

resulting change in the generated image is processed to determine a direction of movement of the

relief object and to generate a corresponding directional control signal that causes the display

screen pointer to move in a corresponding direction. For example, if a finger is rolled to the

user's right, the left side of the image is no longer detected and the right side of the image

increases. This causes the image processor to generate a right directional confrol signal that is

used to move a displayed cursor to the right. Ln a similar manner, the cursor may be moved in

other directions.

The "click" of known mouse devices for highlighting a displayed object may be

implemented in the preferred embodiment of the present cursor control device by detecting the

absence of a previously detected image and then timing the interval of image absence before the

image reappears. If the image reappears before the interval exceeds a predetermined maximum

interval length, a "click" operation is implemented. In a similar manner, a "double click"

operation may also be implemented. Also in a similar manner, both the "click" and "double click" operations, as well as other special actions, may be initiated using other combinations of

changes to the relief object images and may also be implemented to accomplish the "click and

drag" functions of known cursor control devices.

Likewise, a computer control device of the present invention may use a relief object

image generator having a pressure-variable impedance layer to generate control signals that

implement the "click," "double-click" and "drag" functions, as well as other special functions or

actions. In these implementations of a computer control device, a gradual increase in pressure

caused by the relief object on the flexible conductive layer generates a corresponding increase in

the current flowing through the flexible layer that intensifies the image. By sensing this

changing intensity and determining when it crosses a predetermined threshold, the processor may

detect an image change and generate a control signal to activate a special function such as a

"click," "double-click," or "drag" function. Functions activated by multiple signals, such as a

"double-click," may be implemented by detecting repetitive crossings of the image intensity

across a single threshold or a series of crossings across multiple thresholds.

The computer control device of the present invention may also be used for operational

parameter control. In a manner similar to that discussed above for the cursor control device, the

processor may detect changes in the relief object image so a user may select or activate a

computer peripheral or subsystem. In a similar manner, the processor may detect other changes

to the relief object image as commands to select and adjust specific control parameters for the

selected computer peripheral or subsystem. For example, a computer operational control device

of the present invention may be mounted in the housing of a computer monitor. An image

processor and memory of the control device processes images of a finger or other object

produced by the relief object image generator. By employing the "click" and "double-click" implementations described above, the user may select a confrol parameter for the monitor, such

as contrast or brightness. For example, rolling a finger on the relief object image generator may

produce a changing image that may be processed by the image processor to generate a control

signal that selects monitor brightness, for example. Continuing the example, rolling one's finger

to the right may result in the image processor generating a control signal that increases the

monitor brightness while processing a finger image rolling to the left may result in a confrol

signal that decreases the monitor brightness.

These and other advantages and benefits of the present invention may be ascertained from

the detailed description of the invention presented below and the drawings discussed therein.

Brief Description of the Drawings

The accompanying drawings, which are incoφorated and constitute a part of the

specification, illustrate preferred and alternative embodiments of the present invention and,

together with a general description given above and the detailed description of the embodiments

given below, serve to explain the principles of the present invention.

Fig. 1 depicts a relief object image generating system made in accordance with the

principles of the present invention which uses an inorganic electroluminescent device;

Fig. 1A depicts the electroluminescent device of Fig. 1 having a concave surface to

facilitate placement of a rounded relief object;

Fig. 2 depicts an embodiment of the present invention that insulates the relief object from

the current of the alternating current source in Fig. 1;

Fig. 3 depicts an embodiment of the present invention in which an organic

electroluminescent device is used; Fig. 4 is an embodiment of the present invention using a reduction lens and sensor array

to provide an electrical data representation of a relief object image;

Fig. 5 depicts an embodiment of the present invention with a sensor array which is

approximately the size of the elecfroluminescent device for use in thin profile applications;

Fig. 6 is a top plan view of a keyboard of a portable computer showing a location for a

fingeφrint imaging system of the present invention;

Fig. 7 A is a depiction of a fingeφrint sensed by the sensor array shown in Fig. 5;

Fig. 7B is a depiction of a change in the image of the fingeφrint shown in Fig. 8 A that is

processed to generate a directional control signal;

Fig. 8 is flowchart of exemplary processing performed on images to generate directional

confrol signals and function select control signals;

Fig. 9 is a depiction of an alternative embodiment of the computer access

control/parameter control device of the present invention integrated with a document reader;

Fig. 10 is a block diagram of a system in which the fingeφrint imaging device of Fig. 6 is

used to control access to a conference host server; and

Fig. 11 is a flowchart of an exemplary method to control access to a conference host

server.

Detailed Description of the Invention

A relief object image generator that may be used to accomplish a practical

implementation of computer access control and user/computer interface control is shown in Fig.

1. Relief object image generator 10 includes a single electrode electroluminescent device 12 and

an electrical current source 14. The electrical current source has a lead 16 which is coupled to electroluminescent device 12, and a second lead 18 for coupling current to a relief object when it

is placed against or proximate to elecfroluminescent device 12. In response to the current

coupled from the relief object to electroluminescent device 12, different areas of

electroluminescent device 12 generate light at intensities which correspond to the amount of

current coupled to an area of elecfroluminescent device 12. Elecfroluminescent device 12 may

be constructed from known inorganic elecfroluminescent devices that typically include two

planar electrodes which are mounted at opposite ends of the electroluminescent device so they

cover the length and width of the device and are aligned with one another. This type of structure

is used, for example, to provide a back-light for a liquid crystal display. By fabricating the

electroluminescent device with only one elecfrode and coupling a current source to the relief

object, the features of the relief object couple current differently to the electroluminescent device

to selectively stimulate areas of the elecfroluminescent device and produce an image of the relief

object. Electroluminescent device 12 is formed with a slightly concave surface (Fig. 1A) to

facilitate placement of a rounded relief object, such as a fingertip, against device 12.

Elecfroliurύnescent device 12 may be an inorganic elecfroluminescent device or an

organic electroluminescent device. Organic electroluminescent devices include thin sublimed

molecular films such as tris (8-quinolinolato) aluminum (III) commonly known as Alq or light-

emitting polymers having specialized structures which provide positive and negative charge

carriers having high mobilities. The light-emitting polymers include poly (p-phenylene

vinylene) or PPV, soluble polythiophene derivatives, and polyanilene which may be applied by

known coating techniques such as spin or doctor-blade coating. Prototypes of these devices are

manufactured and available from Uniax Coφoration of Santa Barbara, California. Electroluminescent device 12 in Fig. 1 is an inorganic elecfroluminescent device.

Inorganic electroluminescent device 12 includes a fransparent elecfrode 22, a light emitting layer

24, and a dielectric layer 26. Current source 16 is an alternating current (AC) source. Elecfrode

22, light emitting layer 24, and dielectric 26, are all preferably planar materials and are structured

so that electrode layer 22 has a first surface 30 which lies along one surface of light emitting

layer 24 and dielectric layer 26 has a first surface 34 which lies along the opposite planar surface

of light emitting layer 24. Lead 22 from alternating current source 14 is coupled to fransparent

elecfrode 22 and lead 18 extends from alternating current source 14 to a relief object 20. One

way to provide a second lead is to place a pad of insulating material (not shown) along one end

of dielectric layer 26 that is exposed for contact with a relief object. The second lead may then

be placed on top of the insulating layer so that a relief object brought in contact with the exposed

area of dielectric layer 26 may also be coupled to alternating source 14. In this arrangement lead

18 may be fixed to the insulating pad located at one end of dielectric layer 26 so it is not easily

moved to a position where alternating source 14 is short circuited.

Transparent elecfrode 22 is, preferably, a polymeric material coated with a fransparent

elecfrode composition such as indium tin oxide (ITO). Elecfrode 22 is transparent to permit light

generated by light emitting layer 24 to pass through with little attenuation or modulation.

Light emitting layer 24 may be a coating of light emitting particles applied and adhered to

the first surface of transparent elecfrode 22 utilizing a binding agent. The coating is preferably a

phosphor material such as zinc sulfidexopper (ZnS:Cu) although materials such as zinc

sulfide:manganese (ZnS:Mn) may be used as well. Alternatively, light emitting particles may be

dispersed in dielectric layer 26. In this electroluminescent device, the light emitting layer is not a

distinct layer inteφosed between the dielectric layer and fransparent elecfrode but is suspended in the dielectric material, preferably in a uniform manner. For example, the phosphor material may

be dispersed in an insulating dielectric material such as barium titanate (BaTiO₃). Furthermore,

selection of the specific materials for the phosphor, as well as for other particles of the

elecfroluminescent device, are partially based on the interaction of the particles with and their

effect on the emitted light. Some materials have physical properties that are manifested in

refractive or reflective optical characteristics that help concentrate emitted light in a

hemispherical direction toward the sensor. Although the material disclosed for transparent

elecfrode 22, light emitting layer 24, and dielectric layer 26 are exemplary, they are not the only

materials that may be used. For example, transparent elecfrode 22 may also be made from zinc

oxide:aluminum (ZnO:Al) and other light emitting particles such as zinc silicate (Zn₂SiO₄) and

zinc gallate (ZnGa₂O₄) may be used. The dielectric material may be from a variety of materials

such as yttrium oxide, silicon nitride, or silicon oxy-nitride.

While the dielectric material may be translucent, it is, preferably, substantially opaque.

This optical property blocks most of the ambient light that enters the dielectric layer. Because

the dielectric layer conducts the current generated by the relief object so it stimulates the light

emitting particles, an opaque dielectric layer permits the light sensed by the sensor array to be

primarily the light generated by the relief object. The ambient light from the environment of the

relief object is attenuated by an opaque dielectric layer and does not generate optical noise that

may interfere with the generation of the relief object image.

Also, the capacitive effect provided by the dielectric layer between a relief object and the

transparent electrode, is not required for some applications. For example, when the relief object

to be imaged is a person's finger, dielectric layer 26 is not required in order to produce an

acceptable image and the upper surface of light emitting layer 24 may be exposed. The finger being imaged possesses sufficient electrical capacitance that the finger can be imaged by an

inorganic single elecfrode elecfroluminescent device having a light emitting layer 24 with its

upper surface exposed, a fransparent elecfrode 22, and an alternating current source 14.

Alternating current source 14 may output a root-mean-square (RMS) voltage in the range

of 20 to 300 volts having an output frequency in the range of approximately 50 Hz to 20 KHz.

To adequately drive 6.5 square centimeters (about one square inch) of the light emitting layer

disclosed above, a current in the range of 100 to 500 microamperes (RMS) is typically required.

The light emitted by the phosphor and the materials disclosed above is within an emission

spectra which is typically visible and often in the blue, blue-green, and green wavelengths.

While the system is discussed with reference to radiation being emitted in the visible light

portion of the radiation spectrum, other materials emitting radiation in other portions of an

emission spectra may be used and remain within the principles of the present invention.

One way to construct system 10 is to modify the design of a known electroluminescent

(EL) lamp. These devices are well known and an exemplary EL lamp is that manufactured by

Durel Coφoration of Chandler, Arizona and designated as part number DB5-615B. EL lamp

structure differs from the structure shown in Fig. 1 in that the exposed surface 38 of dielectric

layer 26 is bonded to an opaque elecfrode, such as aluminum, silver, or carbon. When an

alternating current source is coupled to an EL lamp, the current passed from the opaque electrode

to the fransparent electrode excites the light emitting particles causing them to generate light.

However, such a structure is inoperative to image relief objects as the opaque elecfrode provides

a steady state flow of current across its area. The inventors of the present invention have

modified the EL device design by eliminating the opaque elecfrode and exposing dielectric layer

26. By providing the second lead from alternating source 14 at a insulated pad located at an end of dielectric layer 26, a relief object brought in contact with dielectric layer 26 may also be

placed so it contacts lead 18. As a result, those portions of the relief object which directly

contact dielectric layer 26 provide current at a magnitude different from the current provided at

the portions of the relief object which are not in direct contact with dielectric layer 26. This

modification of an EL lamp and the use of a modified EL lamp to image a relief object is

disclosed in co-pending patent application S/N 08/926,277 entitled RELIEF OBJECT IMAGE

GENERATOR.

The dielectric layer/light emitting particles/transparent elecfrode structure may be

electrically modeled as a capacitor in parallel with a resistor. In the materials preferably used to

construct the present invention, the capacitance of this structure is in the range of 2 to 6 nFarads

per 6.5 square centimeters (about one square inch) and the resistance is in the range of 50 to

1,500 KΩ per 6.5 square centimeters (about one square inch). The amplitude of the output

voltage of alternating current source 14 may be adjusted to alter the intensity of the emitted light

which corresponds to the ridges of the relief object. Current sensing or current limiting circuits

may be coupled to the second lead from alternating current source 14 to ensure the current

provided to a relief object adheres to international regulatory limits for applications where the

relief object is a portion of a person.

The light generated by the relief object image generator is governed by a complex

relationship between the self-impedance of the relief object and the frequency dependent

phosphor emission transfer function of the electroluminescent device. The relief object self-

impedance may include capacitive, ion fransport, and resistive components and has been shown

to vary as the reciprocal of input voltage frequency and the inherent capacitive coupling between the electroluminescent device and the relief object. For example, in comparison with a shallow

valley, a deep valley on the surface of the relief object is farther removed from the surface of the

elecfroluminescent device and exhibits a smaller capacitive coupling with the electroluminescent

device. Its capacitive impedance is therefore larger than that exhibited by a shallower valley

which is closer to and more strongly coupled with the elecfroluminescent device. This

characteristic allows areas of the relief object not proximate to the surface of the

elecfroluminescent device to conduct AC current and to illuminate a portion of the

elecfroluminescent device. The intensity of the illumination is proportional to the physical

separation of the relief object and elecfroluminescent device at that point. As the voltage

frequency is increased, the illumination intensity associated with a given separation decreases,

but this change in illumination intensity is less for points closer to the elecfroluminescent device

surface than for those further away. This phenomena results in an apparent increase in the

optical confrast of the relief object image. The voltage amplitude may then be increased to

compensate for the lower intensity of the image segments associated with the relief object ridges

which are proximate the elecfroluminescent device. However, the optical fransfer function of the

phosphor is strongly related to frequency with the optical illumination from an

elecfroluminescent device at a given voltage increasing rapidly with an increase in the voltage

frequency. Thus, the self-impedance of the relief object and the fransfer function of the

elecfroluminescent layer compete. Consequently, the frequency and amplitude output of the

current source may both be varied to optimize the intensity and contrast of a relief object image

for a given relief object/electroluminescent device combination. Furthermore, evidence suggests

that, associated with the frequency dependency, an additional interrelationship exists between image contrast and the waveform of alternating current source 14. This interrelationship is an

extension of the convolution of the relief object self-impedance and phosphor optical fransfer

functions described above and relates to the manner in which the electrical energy is locally

stored within the image plane of electroluminescent device 12 and subsequently translated into

emitted light. Thus, relief object image intensity and confrast may be additionally optimized by

varying the waveform of the signal output by current source 14.

A system that includes an electroluminescent device which may be used without a current

limiting or sensing circuit is shown in Fig. 2. Using like numerals for like structure, system 40

includes fransparent elecfrode 22, light emitting layer 24, and dielectric layer 26. The various

materials and structure discussed above with the embodiment of Fig. 1 are likewise applicable

for the embodiment shown in Fig. 2. In addition to these elements, system 40 includes a variable

impedance layer 44 and a flexible elecfrode 46 to which the second lead from alternating current

source 14 is coupled. The first lead 16 from alternating source 14 is coupled to transparent

elecfrode 22 as discussed above.

Variable impedance layer 44 is comprised of a non-conducting, compressible polymeric

material in which conductive and/or capacitive particles are suffused. The conductive/capacitive

particles are distributed throughout the polymeric material and are separated from one another by

a distance which is slightly larger than the diameters of the particles. The conductive/capacitive

particles may be low density polymeric or ceramic spheres coated with a metallic layer.

Magnetic particles may also be added to the composition of the variable impedance layer to

improve electrical conductivity. By varying the number of conductive/capacitive particles per

unit volume, the size of the particles, the conductive/capacitive properties of the particles, the

bulk material modulus of the polymeric material, and other known factors, the impedance of a conductive path from one surface of variable resistance layer 44 to the opposite surface as a

function of pressure applied to the first surface may be designed to vary over a wide range.

Where the particle sizes are small and the thickness of the polymeric material is thin, high spatial

resolution of localized pressure is possible. Preferably, the diameters of the

conductive/capacitive particles and non-conductive metric polymers should be smaller than the

smallest resolution element desired for the image. The thickness of variable impedance layer 44

should approximate the same resolution element size. Preferably, the thickness of the variable

resistance layer is in the range of 50-100 micrometers. Variable impedance layers which may be

used in the device shown in Fig. 2 are disclosed in U.S. Patent Numbers 5,209,967 and

4,624,798. Preferably, flexible electrode 46 is made of a thin polymer such as polypropylene or

polyester that is less than 25 micrometers in thickness and having a very thin sputtered metallic

coating.

When a relief object 20 is brought in contact with flexible elecfrode 46, those portions of

the relief object which directly contact flexible elecfrode 46, i.e., ridges 50, locally compress

impedance layer 44 to form a conductive path to dielectric layer 26. This conductive path allows

current to move from flexible elecfrode 46 through impedance layer 44, dielectric layer 26 and

light emitting layer 24 to fransparent electrode 22. This current flow excites the light emitting

particles in the flow path so the particles emit light at an intensity that corresponds to the

magnitude of the current. As the pressure in the areas adjacent valleys 52 of relief object 20 do

not compress those areas of impedance layer 44 as tightly as those areas adjacent ridges 50, the

conductive paths in the areas adjacent valleys 52 have electrical impedance that is greater than

those areas adjacent ridges 50. Consequently, the light emitting particles aligned with the

relatively uncompressed areas of impedance layer 44 emit light having an intensity that is less than that generated by the more tightly compressed areas. Accordingly, an optical image of the

relief object is generated where light is more intense at the areas corresponding to the ridges of

the relief object and less intense at the areas where there are valleys in the relief object .

Flexible electrode 46 and impedance layer 44 provide a pressure-to-optical conversion of

the relief features of the relief object. As a result, the light absorbing and reflective properties of

the relief object do not affect the image generated by the device shown in Fig. 2. Furthermore,

flexible elecfrode 46 isolates the relief object from the current output by alternating current

source 14. As the electrical coupling mechanism from the relief object to electrode 46 and

impedance layer at 44 to dielectric layer 26 is primarily impedance, altering the amplitude of the

output voltage still adjusts the intensity of the light emitted from the light emitting particles

receiving current from flexible elecfrode 46.

A system having a relief object image generator which utilizes an organic

electroluminescent device is shown in Fig. 3. The elecfroluminescent device 60 includes an

anode 62, an organic layer 64, and a pixelated, low work function metalization layer 66.

Preferably, anode 62 is fransparent and may be formed by coating a base substrate of glass or

plastic with indium tin oxide (ITO). Organic layer 64 is formed by depositing a thin film layer

such as polyaniline over the ITO and then an electroluminescent polymer such as poly (2-

methoxy-5-(2'-ethylhexyloyx)-l, 4-phenylene vinylene), also commonly known as MEH-PEV,

is deposited over the polyanilene. A metal, such as calcium or aluminum, is deposited over

organic layer 64 to form pixelated, low work function metalization layer 66. Preferably, current

source 14 is a direct current (DC) source which outputs a voltage of approximately 10 V at

approximately 40 milliamperes. If the relief object to be imaged is capable of absorbing relatively high voltage drops at

current levels of a few milliamperes, then the relief object may be brought in contact with a lead

from current source 64 and placed against electroluminescent device 60 for imaging. To further

reduce the current magnitude brought in contact with a relief object, a pressure- variable

impedance layer is inteφosed between the relief object and the organic layer. The pressure from

the ridges of the relief object generate a lower impedance path through the impedance layer than

the pressure from the valleys of the relief object. The current from the current source is then

coupled at different magnitudes to the electroluminescent device. The number of holes and

electrons generated by an area of the electroluminescent layer is proportional to the magnitude of

current coupled to the area. The recombination of these holes and electrons generates photons

with the intensity of the resulting light being dependent upon the number of holes and electrons

generated in an area. Use of a pixelated low work function metallic layer, such as aluminum or

calcium, defines discrete areas for coupling current from a impedance layer to anode 62. The

variable impedance layer electrically isolates the relief object from the current source to reduce

the current magnitude to which a relief object may be exposed.

As shown in Fig. 4, system 10 is aligned with a reduction lens 70 and an integrated circuit

sensor array 72. Reduction lens 70 and integrated circuit sensor array 72 are well known in the

art and are typically used with the relief object image generators that require a separate, indirect

light source. The system of the present invention reduces the size of the generated image so the

sensor array may be a smaller, and hence, a more economical size. Still, this system requires the

distance from the relief object to the sensor array 72 to be several times the focal length of the

reduction lens 70. While the system of Fig. 4 depicts the use of a reduction lens to transfer the

image generated by an elecfroluminescent device to a sensor array other known optical elements may be used for the image fransfer including, but not limited to, reduction lens systems of other

configurations (e.g., doublets, triplets, cylindrical, etc.), curved reflective optics, fiber optic

bundles, or combinations of any or all of the above.

In applications where a thin profile is required, such as cellular phones, portable

computers and the like, reduction lens 70 may be eliminated and a sensor array 78 placed along

the exposed surface of fransparent electrode 22 as shown in Fig. 5. Sensor array 78 is typically

not of the conventional integrated circuit type to reduce cost. Instead, sensor array 78 may utilize

low cost processes such as those developed in the flat panel display industry involving the

application of semiconductor material onto an insulating substrate. Such exemplary processes

include amoφhous silicon on glass and low temperature polysilicon on glass or plastic film. The

signals from these sensor arrays may then be provided to a computer, either embedded or

external, for further image processing.

In operation, an elecfroluminescent device having a single, transparent elecfrode is

coupled to a current source so that one lead from the current source is coupled to the fransparent

elecfrode and a second lead from the current source is left exposed near an exposed surface of the

elecfroluminescent device in such a manner as to essentially require contact by a relief object

proximate the exposed surface of the electroluminescent device. Preferably, the second lead is

fixed to an insulator mounted at one end of the exposed surface of the electroluminescent device

and physically separated from that exposed surface by a distance greater than the maximum ridge

to valley distance for the relief object. A relief object is brought into contact with the exposed

surface of the elecfroluminescent device and also coupled to the second lead of the current

source. The current through the relief object is coupled, either sfrongly at the ridge contacts or

weakly at the valleys, to the elecfroluminescent device. Those light emitting particles aligned with the ridges of the relief object cause the elecfroluminescent device to generate light at an

intensity greater than those light emitting particles aligned with the valleys of the relief object.

The difference in the intensity in the light generated by these particles forms an optical image of

the relief object.

An alternative relief object image generator includes a variable impedance layer that

covers the exposed surface of the elecfroluminescent device and a flexible elecfrode that is

provided over one surface of the variable impedance layer. The first lead of the current source is

coupled to the fransparent electrode and the second lead is coupled to the flexible electrode.

When a relief object is pressed against the flexible elecfrode, localized pressure corresponding to

the ridges of the relief object compresses a portion of the impedance layer to form a conductive

path having less electrical resistance than the portions of the impedance layer proximate the

valleys of the relief object. As a result, currents through the conductive paths corresponding to

the ridges have magnitudes that are greater than those through the conductive paths

corresponding to the valleys. The higher magnitude currents coupled to the elecfroluminescent

device generate light at an intensity greater than those portions of the electroluminescent device

coupled to the currents corresponding to the valleys. The light generated by the

elecfroluminescent device forms an optical image of the relief object where light areas

correspond to the ridges of the relief object and darker areas correspond to the valleys of the

relief object. The optical images of both embodiments may be focused by a reduction lens and

sensed by an integrated circuit sensor array or provided to a one-to-one sensor array for

conversion to electrical signals.

System 10 of Fig. 5 may be mounted in a keyboard of a computer as shown in Fig. 6.

Keyboard 100 is a typical QWERTY keyboard having function keys 104 and system 10, like the one shown in Fig. 5, is mounted under space bar 106 so a user can place a finger against exposed

surface 38 of dielectric layer 26. Although the relief object image generator of Fig. 6 is

described with particular reference to system 10 of Fig. 5, the reader should appreciate that relief

object image generator 10 may include an organic or inorganic single elecfrode

elecfroluminescent device and the inorganic electroluminescent device may include or not

include a dielectric layer 26. An image processor and memory (not shown) are coupled to sensor

array 78 to receive and process an image of a user's fingeφrint. Preferably, the image processor

applies an image compression or minutia extraction algorithm to the electrical signals generated

by sensor array 78 to produce unique fingeφrint descriptive information corresponding to the

optical image. The descriptive information may then be stored or used for further processing or

transmitted to a remote location. The image processor and memory may be the processor and

memory for the computer. Alternatively, the processor and memory may be implemented in an

application specific integrated circuit (ASIC). The program or firmware that controls the

operation of the processor may be controlled by the operating system for the computer if the

computer processor and memory is utilized or may be stored in a non-volatile memory within the

ASIC. For access confrol, the image processor compares a received image or descriptive

information of a fingeφrint to fingeφrint images or descriptive information for authorized users

stored in fixed or portable memory. In this application, fixed memory applies to the memory

physically resident within the relief object image generator or the computer to which the image

generator is coupled. Portable memory is any information storage media or device which is not

physically resident with the relief object image generator but is typically controlled by the user.

This includes, but is not limited to, printed data in the form of symbology, optical laser cards, smart chip cards, passive and active RF cards and magnetic stripe cards. The image processor

includes a reader for one or more forms of portable memories if authorization data stored a

portable memory is used for generation of an access granted signal. Such readers are well known

within the art. If the image or descriptive information for a user's fingeφrint matches the image

or descriptive information for an authorized user, the image processor generates an access

granted signal that may be used to activate the computer for the user. As shown in Fig. 6, system

10 is preferably mounted where a cursor confrol device, such as a mouse, is typically located.

However, alternative locations may be used, such as in the upper right corner or in place of the

arrow keys, or system 10 may be mounted within a housing and coupled to a computer through

an electrical cable or the like.

A system in which an access confrol device integrated with a computer is used to identify

on-line conference participants is shown in Fig. 10. As shown there, an open network 500

couples the plurality of users 504a-504d to a host conference server 508. Host server 508 may be coupled directly to the open network, such as the Internet, or it may be indirectly coupled to the

open network through an ISP or the like. The host server may be one that supports conferences

for children or may be a host server sponsored by a coφorate organization for the discussion of

research projects or other confidential matters on-going in a company's business. User stations

504a-504d may be LBM PC compatible computers or the like having sufficient memory and

processor capability to support an open network browser 506 that typically supports a variety of

open network communication protocols. An application program 510 is also provided in

computers 504a-504d that captures image data from the relief object image generators 514 which

may be integrated in the computer and either formats it for fransmission or generates a set of identification data corresponding to the image data. Such a fingeφrint recognition program is

known and, for example, is available from The Phoenix Group, Inc. of Pittsburg, Kansas.

Fingeφrint image data 582 or a set of identifying biometric data for authorized users may

be collected by using a relief object image generator of the present invention or other known

fingeφrint imaging device. The image data or biometric data are stored in an authorized user

database 518 maintained at the host server 508. A user personal identification number (PLN) 580

may be stored in a record 584 in association with the image or biometric data assoicated with a

user. The authorized user identifying data may be collected at retail stores of the sponsor of on¬

line conferences. For example, a sponsor of children's conferences may image fingeφrints of

children at toy stores or other outlets of consumer goods for children. The data collected at

various outlets may then be stored in the authorized user database.

Once a user has obtained access to one of the computers 504a-504d and activated the

browser 506 for open network communications, the process shown in Fig. 11 is performed. The

process begins with the user establishing a communication session with host server 508 for the

puφose of attempting to gain access to a conference supported by server 508 (Block 550).

Server 508 then queries the user to submit a user identification (Block 554). An application

program 510 within computer 504a-504d images a relief object placed on the fingeφrint imaging

device 514 integrated in the computer as discussed above (Block 556). The application program

encrypts and formats this image data in a user identification message 530 for transmission to the

host server or processes the image data to generate a set of biometric user identification data for

transmission in the identification message (Block 560). The message is fransmitted to the host

server (Block 562). The user's computer and host server 508 may use a public/private key

encryption scheme to require real-time verification and authentication of the user. Such a scheme reduces the likelihood that an unauthorized user can intercept a user identification

message having identification data corresponding to an authorized user and then later use the

identification data to emulate the authorized user.

Once the server receives the user identification message, it parses the message and

extracts the user identification data (Block 564). Preferably, the user identification data includes

a PLN or user name that may be used to point to a particular user in the user database maintained

at the host server. Using the PLN 580 or the like, a corresponding user record 584 may be located

in the authorized user database 518 and the identification dataset (such as image relief data) in

the record 584 compared to the identification dataset (such as the image relief data) extracted

from the user identification message (Block 566). By using a PIN, the search time of locating

image relief data for a user is substantially reduced because all records do not have to be

examined to locate a potential match. If no PLN is provided then the identification dataset may be compared to all identification datasets stored in the authorized user database to determine

whether the user is authorized for conference access (Block 568). If the identification dataset

from the user identification message corresponds to an identification dataset in the authorized

user database, an access granted message is fransmitted to the computer from which the user

identification message was fransmitted and access is granted to the user (Block 570). Thereafter, messages from the computer requesting access to a conference supported by host server 508 are

then accepted and processed. Otherwise, data messages identified as originating from the

computer from which user data were not verified are thereafter rejected (Block 572).

System 10 of the present invention may be coupled to or integrated into a computer

system such that the alternating current source of a relief object image generator has an electrical

potential maintained across the elecfroluminescent material and the sensor array and image processor are powered, even when the computer system is in the "off' state. Alternatively, sensing circuitry may be coupled to the alternating current source to detect current being pulled

through the elecfroluminescent device in response to an individual touching the

elecfroluminescent material. The sensing circuitry of the alternative embodiment may be

coupled to a power switch, such as a relay or varistor, that is activated in response to current

being detected and the activated power switch applies electrical power to the sensor array and

image processor for operation of the access control function. In response to the image processor

determining that image data it generates corresponds to stored image data, an access granted

signal is generated that may be coupled to another power switch. This power switch applies

power to the remainder of the computer system. This embodiment maintains power to the access

confrol device and activates a power switch to apply power to the computer in response to the

access confrol device generating an access granted signal. The alternative embodiment includes

sensing circuitry that detects current being pulled from the alternating current source and a first

power switch is activated to apply power to the sensor array, memory, and image processor of

the access confrol device. If the access confrol device generates an access granted signal then a

second power switch is activated and power is applied to the computer. The access granted

signal may be a binary signal or it may include information regarding the correspondence

between the generated image data and the stored image data. For example, the generated image

data may identify a particular authorized user having image data stored in the memory of the

access control device. The access granted signal may contain identification of the authorized

user and this signal may be provided to an initialization module, such as an initialization

command file or hardware initialization controller such as a BIOS circuit, for computer initialization. In response, the initialization module selects predetermined configuration data that

corresponds to the user identified in the access granted signal. This configuration data may

activate the operating system resident on the computer system, configure peripheral settings to

initial values associated with the identified user, log the user onto a LAN or the Internet, and/or

start programs or applications authorized for the identified user. Additionally, the access granted

signal may be provided to a computer coupled to the access confrol device through a LAN, WAN

or other known type of communication link. Likewise, the configuration data may be used in a

computer connected to the access control device or it may be provided to a computer coupled to

the access confrol device through a LAN, WAN or other known type of communication link.

After a user has been verified for computer access, the image processor may be used for

providing descriptive information generated from an image of a person's finger or other relief object to a remote site. For example, a person may place a finger on relief object image

generator 10 so the image processor receives descriptive information from an image of the finger

from sensor array 78. The image processor may then provide that descriptive information as a

data file for transmission to a remote site, such as a bank processing center, to authenticate the

user's authorization to access a financial account. Transmission of the relief object image or

corresponding descriptive information may also be used to access other information such as real¬

time images of one's child at a daycare center over an open network such as the internet. Thus,

persons not having a child at the day care center would be less likely to gain access to the images

of children's activities for improper puφoses.

System 10 may be used to provide cursor control signals as well as access control. The

generation of cursor confrol signals is preferably performed in accordance with the movement of

a user's finger on surface 38. Thus, embodiments of the present invention that include cursor control functions may also use relief object image generators that use other mechanisms for

image generation other than elecfroluminescent devices. For example, U.S. Patent No. 5,325,442

discloses a relief object image generator that uses capacitive sensing to generate a relief object

image. In addition, the other known optical technologies earlier described may also be used for

this type of application, as could other imaging devices that may meet the geometrical constraints

for such applications. Such image generators are within the principles of the present invention

for cursor confrol functions such as those discussed in more detail below. As shown in Figs. 7A

and 7B, movement may be detected by evaluating the image of a fingeφrint. For example, the

fingeφrint in Fig. 7A is a fairly full image of a fingeφrint generated by a relief object image

generator while the image of Fig. 7B resembles that of Fig. 7A except the left portion of the

image is absent and additional features are present on the right side. This image differential

indicates that the user's finger has been moved to the left. Detection of this movement may be

used to move a displayed cursor to the left.

An exemplary process for an image processor implementing a method for providing

cursor confrol using a relief object generator is shown in Fig. 8. That process is preferably

performed after the system processes an initial image of a person's fingeφrint to determine

whether the user can access the computer system. The process begins by determining whether an

image of a person's fingeφrint remains stable (step 120). Stabilization may be determined by (1)

calculating a ratio of the number of changing sensor elements for the image over a predetermined

period of time to the total number of sensor elements for the image and (2) comparing the ratio to

a predetermined threshold that indicates a stable image. Other measurements may be used to

evaluate the amount of image change such as the calculation of a LI or L2 distance between two

images taken at different times. Once the process determines the image is stable, it determines when movement occurs (block 122). Movement may be detected by one of the methods

discussed for stabilization evaluation, If no movement is detected, the process determines if a

"click" is active (block 124) and if it is not, the process continues to look for movement.

Processing during an active "click" is discussed below. If movement is detected, the new image

is compared to the stored stable image (block 126). If the image is not substantially absent

(block 128), the process continues by determining the direction of the movement (block 130) and

generating a corresponding directional confrol signal (block 132). The directional confrol signal

conforms to directional confrol signals generated by a known mouse or other cursor control

devices.

If the image of the finger is substantially absent, i.e., a substantial portion of the sensor

elements detecting light for the image no longer detect light, an absence timer is initiated (block

134) and the process determines whether an image reappears (block 136) before the absence

timer expires (block 138). If the image reappears before the timer expires, the process checks to

see if a "click" status is active (block 140). If it is not, the "click" status is activated (block 144)

and a "click" timer is activated (block 148). The process then continues to look for movement in

the new image (block 122). If no movement is detected, the process determines whether the

"click" timer has expired (block 150) and if it does expire before further movement is detected, a

highlight confrol signal is generated (block 152). If new movement is detected, it either is

processed to generate a directional control signal or a select function confrol signal. A select

function is determined by detecting another absent image (block 128), determining whether the

image reappears before the absence timer expires (blocks 136,138), and, if it does, determining

whether the "click" status is active (block 140). If it is, the user has double tapped surface 38 and is indicating a "double click." In that event, a select function confrol signal is generated (block

158) to activate a function or the like.

In addition to the "click" and "double-click" special functions and their implementation

described above, several other special functions may be commanded using a system of the

present invention. These functions include the selection of any or all function keys for a

computer system, dragging, highlighting, underlining, left-click/right-click, triple-clicking and

other program specific functions. Some relief object image changes which may be processed to

generate the function signals for these functions include finger rotation, subsequent application

of the same finger in different orientations, swipe (specific direction including up, down,

diagonal, or the like), swipe (specific pattern including tick, cross, circle, or the like), reversing

swipes (including up/down, left/right, clockwise/counterclockwise, vice versa, or the like), two

specific fingers simultaneously and two different fingers sequentially. These features may be

controlled by the processor either as a function of changes in the spatial characteristics of the

image or the intensity of the image.

Detecting intensity changes to generate confrol signals is especially appropriate for

confrol devices having a pressure-variable impedance coating where an operator triggers desired

signals based on the amount of pressure applied to the surface of the elecfroluminescent device.

In these implementations, a gradual increase in pressure caused by the relief object on the

flexible impedance layer generates a corresponding increase in the current flowing through the

impedance layer that intensifies the image. By sensing this intensity and determining when it

crosses a predetermined threshold, the processor detects an image change and generates a control

signal to activate a special function such as a "click," "double-click," or "drag" function.

Functions activated by multiple signals, such as a "double-click," may be implemented by detecting repetitive crossings of the image intensity across a single threshold or a series of

crossings across multiple thresholds.

A system comprised of a relief object image generator, sensor array 78 (or one of the

other sensor arrays discussed above), the image processor, and memory may be used to confrol

operational parameters for a device. Again, the relief object image generator in such a system

may be an electroluminescent device or other known relief object image generators that use

capacitive sensing, alternative optical imaging or the like for image generation. In a manner

similar to that discussed above for the cursor control device, the image processor may detect

changes in the relief object image and generate confrol signals so a user may select an

operational parameter for the device or activate a component of the device. For example, the

parameter confrol device of the present invention may be incoφorated in an automobile or an

appliance. By placing a finger on the relief object image generator and moving the finger, the

user causes the relief object image generator to generate an image of the finger that the image

processor detects and processes. As the image of the finger changes, the image processor

generates confrol signals that are used to select device functions, confrol the operation of the

selected device function, or activate a device component. For example, such a system may be

used to select the windshield wiper function of a car and confrol the wiper speed. Additionally,

such a system may be used to confrol access to a device and then activate an initialization

module for initializing the device to predetermined parameters in a manner similar to that

discussed above for computer initialization following an access confrol determination. The

access granted signal generated by the access control/operational parameter confrol device may

contain identification of the authorized user and this signal may be provided to an initialization

module, such as an initialization command file or hardware initialization controller such as a BIOS circuit, or an initialization module that includes a memory for the storage of parameter

values and confrol signal generators for sending confrol signals corresponding to the

initialization values to components of the device. In response, the initialization module selects

parameter values as defined by predetermined configuration data that corresponds to the user

identified in the access granted signal when the access granted signal contains user identifying

data. This type of access confrol device may be used to initialize device components such as seat

position and radio settings for a car, for example, once the access granted signal has been

generated by the image processor. For systems where the access control device is remotely

located from the device, the access granted signal generated by the image processor may be

transmitted to the device through a communication link which may be wired or wireless.

In a computer system, the operational confrol device may be used to select or activate a

computer peripheral or subsystem. Again, the image processor may detect changes to the relief

object image as commands and generate confrol signals to select and adjust specific confrol

parameters for a selected computer peripheral or subsystem. For example, such a system may be

mounted within the housing of a computer monitor for tilt, pin-cushion, horizontal width and

position, vertical height and position, brightness and confrast control. In response to a highlight

confrol signal being generated in response to the system detecting a "click" operation, a menu of

operational parameters may be displayed. Generation of up and down directional control signals

in response to the corresponding movement of the finger's image, causes the menu to alternately

move the highlight to one of the operational parameters. If the user moves the finger to the left

or right, the corresponding right or left directional confrol signal may be used to increase or

decrease, respectively, the highlighted operational parameter. This description of an operational

parameter confrol device is exemplary only and the reader should appreciate that other types of parameters and greater numbers of operational parameters for a number of devices may be

controlled by a system having a relief object image generator, a sensor array, an image processor,

and a memory with a program or firmware that generates highlight, select, special function

activation, directional, cursor confrol or other confrol signals or the like.

Another embodiment of the present invention is comprised of a single elecfrode

elecfroluminescent device proximate a sensor array that is used to receive data from a writing

stylus. This embodiment builds upon the computer access, cursor confrol and computer

parameter confrol features described above in two ways. First, a conductive stylus is coupled to

the current source and used as a specific type of relief object. As a point of the stylus contacts

and moves against a flexible elecfrode overlaying an elecfroluminescent device, an image is

generated. The image is received by the sensor array, converted to electrical signals and then the

image or descriptive information about the image is stored. The image formed by movement of

the stylus point may be determined by an image processor generating a composite image of the

stylus point trajectory from a series of images of the stylus point stored in memory. This

composite image may then be evaluated to recognize alphanumeric characters or other

symbology from a known set of symbols. In a similar embodiment using the single elecfrode

elecfroluminescent device incoφorating a pressure-sensitive membrane that overlays a surface of

the electroluminescent device as described earlier, the pressure of the stylus creates a

corresponding image which is, again, detected by the sensor and processed by the image

processor. In both of these embodiments, the access confrol/operational parameter confrol device

of the present invention also implements an electronic writing tablet or notepad.

In yet another embodiment of the present invention, the computer access

confrol/parameter control device discussed above may be integrated with a document reader. An exemplary embodiment of an integrated confrol device/document reader 900 is shown in Fig. 9.

The device includes an elecfroluminescent device 10, sensor array 902, fransparent substrate 906,

and an external light source 910. Elecfroluminescent device 10 may be fixedly separated or

spaced apart from sensor array 902 by a gap G to form a slot in which a document may be placed

between elecfroluminescent device 10 and sensor array 902 for imaging. For example, reader

900 may be located near an edge of a computer housing (like device 38 in Fig. 6) so gap G is

exposed at the edge of a computer housing to provide an opening for a business card or similar

sized document between sensor array 902 and electroluminescent device 10. Alternatively,

elecfroluminescent device 10 may be pivotally or slideably mounted to the housing of a

computer so that device 10 may be moved to exposed an upper surface 902a of sensor array 902.

In another alternative embodiment, one of elecfroluminescent device 10 and sensor array 902 is

coupled to a biasing member and the other component is fixedly mounted or both components are coupled to one or separate biasing members so that elecfroluminescent device 10 and sensor

array 902 are urged together. However, placing the edge of a document at the interface of sensor

array 902 and elecfroluminescent device 10 displaces the biased component or components as a

document is pushed between the two components. Removal of the document or other object to

be imaged causes the two components to be urged together by the biasing member or members.

Transparent substrate 906 and external light source 910 are known components. Sensor

array 902 is a sensor array like the one described in U.S. Patent No. 5,349,174. This type of

sensor array has a plurality of elements arranged in a matrix on a fransparent substrate. These

elements are spaced apart from one another and do not occupy all of the surface area of the

sensor such that the sensor array is partially-fransparent. The partially-transparent sensor array

permits light source 910 to be located behind sensor array 902/transparent substrate 906 and still illuminate an object placed on or near upper surface 902a of sensor array 902. Because a sensor

array like the one described in the '174 Patent permits external light source 910 and transparent

substrate 906 to be located so they do not interfere with the operation of the confrol devices using

an elecfroluminescent device like the ones described above, sensor array 902, transparent

substrate 906, and external light source 910 may be used to image objects placed against or near

sensor array 902 without significantly impacting the geometric dimensions of the control device.

After an object to be imaged, like a business card, is placed against surface 902a of sensor array

902 to support the document for imaging, a function key may be depressed to activate light

source 910 and illuminate the surface of the object through fransparent substrate 906 and sensor

array 902. Light reflected by the document is received by sensor array 906 and converted to

electrical signals that are processed by an image processor. Such a device may be used to image

and store business card images or to image documents and generate descriptive data, or extract

image data for storage in a database.

While the present invention has been illustrated by the description of several

embodiments and while the embodiments have been described in considerable detail, the

applicant does not intend to restrict or in anyway limit the scope of the appended claims to such

detail. Additional advantages and modifications will readily appear to those skilled in the art.

The invention's broader aspects are therefore not limited to the specific details, representative

apparatus and method, or illusfrative examples shown and described. Accordingly, departures

may be made from such details without departing from the spirit or scope of applicant's general

inventive concepts.

What is claimed is:

Claims

CLATMS

1. A method for securing access to a conference of users at a host server comprising

the steps of:

storing authorized user identification datasets for a plurality of users in a user

authorization database, the user authorization database being coupled to a host server for

supporting user conferences and the authorized user identification datasets including biometric

data for identifying authorized users for conferences supported by the host server;

extracting a user identification dataset from a user identification message received

by the host server supporting a user conference; and

granting a user computer access to a conference supported by the host server in

response to said exfracted user identification dataset corresponding to one of the authorized user

identification datasets stored in the user authorization database.

2. The method of claim 1 further comprising the steps of:

imaging a user's fmgeφrint with a relief object image generator at a user's

computer communicating with the host server; and

integrating the user's fingeφrint image data into the user identification dataset for

the user identification message.

3. The method of claim 2 wherein the user's fingeφrint is imaged with a single

elecfrode elecfroluminescent device and an alternating electrical current source at a user's computer communicating with the host server.

4. The method of Claim 2 wherein personal identification numbers are stored in association with said user identification data sets and further comprising the steps of:

extracting a user personal identification number (PLN) from the user identification

message;

searching the user authorization database for a user record that is identified by the

user PLN; comparing the user's fingeφrint image data to biometric data associated with a

record identified by the user PIN; and granting a user access to said conference if said user's fingeφrint image data

matches the biometric data stored identified in association with the user PLN.

5. A system for securing access to a conference of users at a host server comprising:

a host server for supporting user conferences; and

a user authorization database storing authorized user identification datasets for a

plurality of users, the authorized user identification datasets including biometric data for

identifying authorized users for conferences supported by the host server whereby the host server

extracts a user identification dataset from a user identification message received from a user's

computer and grants the user's computer access to a conference supported by the host server in

response to the extracted user identification dataset corresponding to one of the authorized user

identification datasets stored in the user authorization database.

6. The system of claim 4 further comprising: a relief object image generator for imaging a user's fingeφrint at a user's computer communicating with the host server so the image of the user's fingeφrint image may

be integrated into the user identification dataset for the user identification message.

7. The system of claim 5 wherein the relief object image generator is a single

electrode elecfroluminescent device and an alternating electrical current source at a user's

computer communicating with the host server.

8. The system of Claim 2 wherein personal identification numbers are stored in

association with said user identification data sets and wherein said host computer extracts a user

personal identification number (PLN) from the user identification message, searches the user authorization database for a user record that is identified by the user PLN, compares the user's

fingeφrint image data to biometric data associated with a record identified by the user PIN, and

grants a user access to said conference if said user's fingeφrint image data matches the biometric

data stored identified in association with the user PIN.