CA2124201A1 - Coded playing cards and other standardized documents - Google Patents

Abstract

An apparently conventional playing card (10) is invisibly coded so that it can only be read face down, by an electro-optic reading means. The card may be of non-laminated conventional card stock which has a substantially white surface conventionally printed with the identification of the suit and value of the card with inks chosen because they are visible but substantially transparent to wavelengths outside the visible range. The face of the card is coded with indicia inklessly marked across its surface with a compound which absorbs wavelengths (outside the visible range) which wavelengths are used by the reading means to read the indicia.
The indicia, invisible to the human eye, correspond to a code (11) which uniquely identifies the card. The card may be laminated from top and base sheets and the code concealed behind the front printed face of the top sheet.

Description

VO 93JJ0870 2 1 .~, ~ 2 ~ :l PCI/US92/09704 CODED p~5rING CARD8 A2~D O~ER 85~D~DIZED DOC~ 8 BACKGROUND OF THE INVENTION
This alpplisation is a continualtion~in-part application of Serial No. 07/501,148 filed March 29, ~0 the disclo~
5 sure of which is incorporated by reference thereto as if fully set forth herein.
This invention relates to a playing card which i~;
coded with an arbitrarily chosen machine~readable indicia not visible to t:he human eye . In one embodiment, a card ' ~:
10 fac:e is coded in a unique pattern visible only in the infrared or ~ltraviolet regions, without being visibly defac:ed. The coded card is an otherwise conventional play-ing card formed frc~m a single non~-laminated sheet c~f flex-ible material (l~card ~tock~ ;uch as paper, pr~ferably 15 coated with a ::ured latex of a~n acrylate~containing polymer .
In anol:h~r embodim~nt, the c:ard is a laminat~d playing card comprising an upper lamina of f lexible card stock, a lower lamina ~base~ o~F the same or anoth~r fl~xible stock, 2 0 and an intermedi~t~ layer sandwiched therebetween . The laminated card i~ coded in the region between the upper lamina and the lower lamina, which region is ref err~d to as the intermediate layer, in a manner such that an alectronic:
device can ielenti~y the ~alue of th~ card alld access wh~t : 25 ever other infc~rmation the code may hav~ been sl~vi~ed to rev~al~, In a 6pec~ ic embodiment, the c:ode indicates to an electronic: 'Sread~r'l (of the hidden code~ what the value of the cars~ and where each card in a dec:k or set of cardæ
i~; to be d~alt wikhout the dealer knowirlg the ideriti~ica-3 0 tiorl of ~he caxd .
P~s one skilled in the art will readily apprec:iate ~coding a deck of playing cards, each wit~ a visible (to the human eye3 code, for example a ~tandard Hollerith pattern or ~'bar c:ode'l, by which each s::ard is uni~ 31y identif ied , 35 is a routine task. To code a card without the code being visible to the human eye, ~30 that a deck of cards may be WO g3/l0870 P~/US9~/~9,~

21~42~l 2 read by a machine viewing only the f aces of the cards which are passed, f ace downwards, over the reading means of a machine, without defacing the cards and essentially without regard for the orientation of the card as it is passed over 5 . he readirlg rneans;, is not a routine task~
Coded playing cards coded as disclo~ed in u. s . Paten~
No. 4r~34,562 to Cuff ~t al, were conventionally marked with a ~inary code along its opposite edges so that the cc: de ~ould be seen by ~he human eye ~read by light in the 10 range o~ visible wavelengths). Since there was no concern about hiding the f act that the cards were coded the n~cessit~ of overprillting the faces of the cards did not arise, and the cards were ma~ked on the side edge~;.
The f ace of a pac:kage of corn chips provided the sub~-15 trate whic:h was marked with machine readable inf ormation overprintedL on humall~readable symbology, each wi~h a different type of ink in U. S . Patent No. 4, 889, 367 to Miller~. The human-readable ink absorbs energy in the visi}:~le wavelength, but insuf f ici~nt ~nergy in another 2 o wavelength range to prevent a bar-code reading machine ~ ~Ireader~ ) from reading the bar code O Such a two-ink printirlg of a ~ar ;c:ode ~n a substrate wa~ well-suîted for a package to be read when passed across a grocery store c:ounter where the la~er reading the bar code rotates until 25 it can read the code. Howev~r, ~ince ~he orientatiorl of the laar code is f ixed on each of the f oregoing su~strates in the '367 and ~562 patents, the code ::an only be read in one dixection by a reader h~ving a f ixed light source.
reover, it is diffi~ult to find infrared or 3 0 ultraviolet absorptiv2 inks which do not absorb in the visil:le region, that is, have ~ssentially no c:olor. Though ink~ ha~ing very ~pecif ic energy absorption and ref lection characterl~tics are commercially available, if only on ~;pecial order, no suggestion or illustrati~e example of an 3 5 in~rared or ultraviolet absorbing in3c which does not sub-: ~ stantially absorb in the visible region, i~ provided in the '562 or '367 patents. Thus the "invisible" bar code of the ~VO 93/10870 h ~ 2 ~12 ~ :~ P~/US92/09704 ' 367 patent, in practice, is limited to use on ccls:~red sub-strates; such as a mustard olor on a bag of chips j or the brown or blue of other snack f oods, Since playing cards traditionally have their face 5 value~; printed against a very white back~r~nd, the prior unavailability of cc~lorles~; ~'inks'~ did not provid~ a practical solution to ~he probleml. Still further, there is no suggestion in ~he prior art as to what kind of infrared "ink" would be unaffected by the repetitive shuffling, 10 sorting, and sliding of playing cards9 face down on a table, all of which actions tend to scuf f the cards and the ink, making it dif f icult to read the code .
Our playing card US2S an essentially invisible bar code which can be r~ad only by an electro-optical reading 15 means which uses light in the infrared or ultraviolet region, as described in greater detail hereinbelow, whether the card is lamillated or nc~t.
In the non-laminated card of converltivnal card stock, the code i~ inklessly textursd or etched into the face of 2 0 the card . By the terms qltextured or etched" (which terms are u~;ed interchangeably h~rein) we mean that the sur~ace is either scuffed (or etched) so that the f ibers of the s::ard stoc:k are disrupted (typically raised) relative to the f ibers which have not been scuf :~ed; or, the surf ace is 25 im~regnatQd without using a pigment~ uch a~; are used in ink~ ut using a dye or micro.. copic powder which has essen!tially no pigmentinS~ value . In either c:ase the surf ace of the card is said to l~e ~'textured" ~ By ~' inkl~ss:ly~' we m~n without using a pigmented liquid or paste used especially for writing or printing. Inkless writings inc:lude the symbols on the screen of a compllter ' ~; monitor or on a television tube, ~;cript or other symbols cut into stone or other durable surface, and me~;~;ages ~n smoke wx itterl across the sky, inter alia .
3 5 For the f ir~;t time, we ha~ve now been able to providé a 3playing s::ard oî car~l stock which can be marked all over the card'~; face, if so desired, then overprinted with the face WO 93~1~870 . PCr/US92/0~

va lue of the card wi~hou~ visibly changing the ~Inormal9~
appearance of the card I or vice versa changing the sequence of operations. The unexpected result of being able to ~::ode a playing card essentially illvisibly by texturing or 5 etching, is that the f ace of the card ma~ e tèxtured or etched with the code repetitively, or the intermediate layer may be textured or e~ched with the code repetitively, thus enabling the card to be read in any generally lateral orientation whatsoever ~ as long as it pas~es over, 10 preferably in contact with, the machine which reads it~, Of course t the card may also be textured or etched with the code. in such a marmer that the reader will read the code in any gen~rally f ixed direction ~ say along the horizontal x-axi~;), whether the card is introduc:ed to the reader from 15 either end along the axis.
More pref ~rably, the card is laminated, as stated above " and only the intermediate layer c:arrie~ the s:~ode i~prirlted on it. A~ in the case of th~ non-laminated card, the intermediate layer may be printed with the code 20 repetitively, thus enabling the card to be read, as before, in any generally lateral crientation whatso~ver, as long a~
the card passes over the machine which reads it. ~nd, as before~ th~ aard may also be read in any generally fixed directionO if the optio~ or flexibillty of presenting the card in an arbitrary lateral orientation is not d~sîred.
More g~n~rally ~he laminated ~mbodim~nt of this inven-tion r~late~ to providing a machine r~adable code in a standardized do~um~nt such as a credit card, ex~cuted , origin~l contract, warranty deeds, bearer bond~, passports, credit cards, id~ntification cards and the like. For exampl , the ubiquitous "pla~tic card" made according to this invention t may h~ve a code hidden within it which i~
relati~ely non susceptible ko wear because it is protected by the upper and lower laminae which have specified optical properties, de~cribed in greater detail herebelow. The upper and lower laminae are self-supporting ~heets of material which ~erves as the top and bas layers, re~pect-- wo 93/10870 2 ~ ~ Ll 2 ~ ~1 PCTtUS92/09704 ively, of the laminated card.
The term "lamina" is used to emphasize the fact that the sheet is self-supporting and of appreciable thicklle6s, at least about 0.5 mil (0.0005 inch) thick. The terms "top layer'^ or 9lupper lay~rl' and 9'base layer"~ 'lower layer"
are used synonymously with "upper lamina" and "lower lamina" herein only because the former terms are less awkward and more familiar ~han the latter. The term "intermediate layer" refers either to a selactively reflective non self~supporting layer typically less than about 0.5 mil thick, or a combination of the non-self-supporting layer with a supporting layer the optical properties of which are immaterial. A non~self-supporting layer, typically consi~ting e~sentially of solid particles from Q.l~m - 5~m (micrometer) may be sputter-coated or ~acuum deposited; particles up to 44~m in average size may be conventionally deposited; while films less than 0.5 mi~s ~0.0005~") thick, ~ay from lO~m to about ~3~m, may be formed by known means. A non-self-~upporting intarmediate layer less than 0~0005~' thick may consist of only the particles which define the code, or such particles supported on a thin film of materi~l~ pref~rably a pol~meric fil~.
The face of the upper lay~r of the standardized doaum~nt carrl~s th~ human-readable insignia and compri~es a ~electively reflectiYe lamina~ substantially fully light-reflective in th~ visible, and substantially transpar~nt (light-permeable) in the infrared or ultraviol~t regions.
The electrical conducti~ity of th~ upper layer is irrelev~
ant, as is that of the base layer, provided such conduct-ivity~ if present, does not interfere with operation of thedevice used to read the codad intermediate layer of the lamin~ted cardD
Though the principle~ upon which the interaction of the components of the laminated ~tandardized document, and more speci~ically, o~ the laminated playing card, are well known in optical physics, the choice of the components with a ~iew to their desired interaction is unigue.

W093/10870 PCT/US92/0~

2 1 ~ r s ~ 6 The device to deal a deck of cards so that a pre-selected '~hand" stored in the memory of the device, is dealt to each player, and to do so in an error-free, repeti~ive manner, has been disclosed in the parent case.
Since the reader (device) is for use by ~ups of card-playing enthu~iasts, it was essential, under the circum-stances, that the device be affordable to ~uch groups. The affordability of the device is also an advantage in those situations where standardized documents other than a playing card, are to ~e read.
The matter of economic~ fur card-playing groups is of particular importance because the game of Contract Bridge is pla~ed by a large segment of the population o~ the world, and the typical person in such a group is not in a position ~o pay much for any d~vice with which he may practice playing presalected hands, or one he uses to teach himself how to play the game more astutely, or to partici pate in the game of Duplicate Bridge.
Duplicate Bridge i~ play~d in essentially the same manner all over the world as ~ test of skill in a game in which the s~me deal is played mor~ than once at different tabl es . Thus it become~ important that many decks of cards be dealt in preselected sets of 13 cards aach to each s~t of comp~titors.
It will now be evid~nt that the appaxatus and coding ~ystem of thi~ invention can al~o b~ used to deal hands in th~ game of poker, or ~ny o*her card game in which specific cards are to be dealt t~ a ~peciied location according to ! ` ' I direGtions proYided ~y the memory of the device.
The deYice is particularly useful as a teaching device ~caus~ an ~lectronic ~chip" an be pro~ided with "teaching hands'~, and the level of th~ game being taught can ~e tail~
ored to th~ expertise of the learner by simply replacing one chip with another.
Further details for playing the game of Duplicate Bridge, or any other ~ard game where a deck of cards is to be dealt in a prescribed ~anner, are not of particular ~ ~-2 l`~7~`2~ l ~WI~) 93/10870 PCI/IJS92/~9704 import~nce here. The thrust of this invention is that, in its most pref erred embodiment, it provides a playing card which can ~e read by a device for manually dealing a deck of cards, or any portion thereof, in a preselected manner, by simply sliding each card, face down~ ~eross `a surface in which electro-optical reading means to identify the card~
and means to match the idenkification of the card with an instruction in the device's memory, result in a si~nal being given to the dealer as to where ~which location) that card is to be dealt.

It has been discov~red that each playing card in a deck of playing cards may be identif ied with machine-readable indicia essentially invisible to l~he human eye, to l5 sort the deck without the per~on sorting the cards seeing their face values . If a p~rson was to ~s:srt a de ::k of cards manually, he would of course, read the printed identi-gication of each card whi.ch designalt~3s i't5 ~ISUi't~ (whether, spades, hearts, diaraonds or clubs3 and it~ designation in the s~it (Ace, King, Queen, etc.)~ To sort the d~ck with a ~readerCi~ each card, face do~n, is manually slid across a surface of ~he reader, to read the contrasted code against khe background, he orientation of the card preferably bsing o~ no con~e~uence~ ~
In a non~laminate (~'card æ~ock") card, ~h~ concealed machine-r~adable coding indicia may b~ (a3 imprinted inkles~ly by t~xturing or etching along ~ach margin of the ¢ard, or t over the ~ntire ~ur~ace of th~ card's face; or ! ~) imprinted with visible-light-pexmeable dyes, along ~ach margin of the card/ or, the entire sur~ace of the card's face~
In a laminated card, the concealed, machin~readable codlng indicia is impri~ted on an intermediate layer, ~ither as a ~ingle set of coding indicia (say, a bar code~
readable from either of two generally axially opposed directions; or, a~ multiple coding indicia (plural sets of bar codes, say) readable from any arbitrary direction so .. . . . - . , , . . . ~ . . . ~ .. . " . . .. .

WO~3/10870 PCT/US92/Ot9j~4 2 ~ 2 ~

long as the card i~ kept face down. The coding indicia may also be imprinted along each margin of the intermediate layer, or, ~he entire surface of the in~erme~iate layer.
If the code is imprinted unidirectionally, say in the S direction o~ the longitudinal axi~ of th~ard,~ then the card will ~e read as long as a portion of the card carrying the imprinted code passes transversely (that is, not paral-lel to the direction in which lines of the indicia are marked on the card) over an electro-optical reading means which identifies the card. The code read is then compared to a predetermined list of locations to determine to which player position (North, South, East, West) the card is to be dealtO A signal is th2n generated to indicate to which position the identified card is to be d~alt,:and the dealer deals the card to the indicated position. The signal m~y be visual, for ~xample a light, or it may be an audio si~nal or a speech processar within the device stating 'INorth'~, "South~, etc~ to identify the location to which the ~ard is to be deIivered.
It is a specific obj~ct of this inv~ntion to provide a non-lam~nated playing card with a surf:ace identifi~d wîth : inkless indicia ~hich are essentially invisible to ~he:
human naked ~ye~ut which can be read by an electro-optical reading means sensi~ive to wavelengths in the infrared or ult~aviolet light regions,~each o~ which is out~ide the :~ : wavelength in th~ ~i ible range, that is, light with wavelength ~horter than about 4000 Angætroms or longer~than ~:: about 7000~ngstroms ~o~ Oq4~m - 0.7~mO or 400 ~m -:700 nm nanom~ters''~. ~he card may be read laterally, either 30 ~ substantially unidirectionally, ~rom either ~nd~but ~ace down; or, without regard for the card's ~ace-downwards later~l orientation.
~ It is another pecific obj~ct of this invention to pro~ide a non-laminated playing card which is coded acros~
:35 it~ entire face, ox along each of the four margins thereof, with inkless indicia which are essentially in~isible to the : na~ed eye but which can be read by an electro-optical .. . ... . . .. .. . . ......... ...... . . . . . .. .. . .. . . . . .

WO93/10~70 ~ ~ 2 ~ cj~ ~ PC~/US92/~9704 reading means sensitive to light in the wavelength range above about 7000 ~ Ang~;troms (700 nm) but belc>w about 2 O 2x105 A, preferably in the infra-red range from about 800 - lO4 nm, more preferably 800 - 2000 nm (near infrared).
Coding with indicia imprinted or otherwi,s~marl~ed acros~
the entire surface or along each margin, any portion of the surface or margin completely identifying each card, allows any portion OI the card to be pass~d over the electro-opti-cal reading means and be read without regard for its face-downwards orien ation.
It is a specific object of this invention to provide a laminated playing card having ~ l ) an upper lamina or top layer which is :~electively light-permea~ble to light in the infrared, ultraviolet and visible regions, and the face of lS the top layer is impriTlted with the value of the card; ( 2 ) a lower lamina or base layer which serve~ as a supporting layer ~Eor (3) an intermediate, s~lectively light-reflectlve coded layer which is sandwiched between the upper and lower lamirlae, ~30 that the c:od on the intermediate coded layer may bs read by a device using light ira a predeterminecl wavelength to which the upper lamina is permeable, and which predetermined wavelength is selectively reflected/-abso~bed by the intermediate layer and coding indi ::ia ther~on, so as ~o pr~vide su~f icient contr~t to be read by a "reader".
The upper lamina i~ made ~rom materiaI which ref lects substarlkia~lly all lighl: in the visible spectrum~ that is, the top layer i5 nearly~opaque. ~he fac:e of the ulpper I J amina i~ printed with ink~ in colors whi~h identify each c:ard in the slæck, and these ink$ on card s~oc:k also reflect substantially ~ll light in the vi ible spectrum. By i'subs-tarltially all light:" we re~er to at least about ~30% of the lLight in the visible ~pectrum being reflected, the remain-ing 20% or less being tran mitted.
3 5 The intermediate layer pref erably ref lects substan-tially all in~rared or ultraviolet light; this layer i~
provided with coded indicia r eadable hy a r~ader which uses WO 93/tO870 PCr/US92/0?7~
2 ~ 2 ~

either infrared or ultraviolet light to read the code. The coded intermediate layer is substantially coextensive with the document. When the documen$ is held up and viewed against a bright light in the visible spectrum, only ~he 5 patterns, specif ic:ally the f ace values o~,-~e playing cards t imprinted with colored inks, and the decorative pattern on the bac:k of the card, can be seen ( depending which layer is directly before the viewer' s eyes), and the c:ode on the intermediate layer is not visible to the human 10 eye. The intermediate layer being sandwiched between the upper lamina and lower lamina i5 held therebetween. The optical properties of the l~ase layer, whethPr it is perme-able to light of any wavelerlgth or not, is not material to its function herein.
It is a spec:i~ic objec:t of this invention to provide a laminated label or other standardized docum~nt the upper (top~ layer of which is made of material which is substan-tially ref lective in the visi'ble spec:trum and is marked with srisible indicia in f~olorled inks, but the material and colored inks are both permeable to infrar~d or ultraviolet light; the intermediate layer is li~ht-ref lective and sub tantially coextensive with the document, the in1:er~
mediate layer. having a code imprinted l;hereupon whic:h absorbs light in a predetermined wavelength range, the int~rmediate 1 ayer being ~;andwiched between the upper layer and ~ base layer which supports the intermediat~ layer, th~s op ic:al pr4perties of whi . h base layer being immaterial to th2 code-r~ading functi~n of the card.
BRXEF DESCRIPTION OF THE DR~INGS
The foragoi2lg and additional obj~::ts and advantages of th~ inv~ntis~n wi:Ll best be understood by re~erence to the following d~1:ailed d~sc:ripltion, ac::companied with schematic illustrations of pre~rred embodiments of the inv~ntion, in which illustraltions like reference numerals ref~r to like 3 S elements J and in which:
Figure 1 i5 a repre~entation of a playing card, speci~Eically the two of spades, sho7ring a typic:al bar .~93/10~70 2~2~ ~t PCT/VS92/097~

1~ :
coding as phantom shaded portions since they are not vi~ible to the naked eye. The bars traverse the width of the car~ in a direction at right angles to the longitudinal axis of tha card and are textured on the face markings of the card7 which of course are not affect~by the`texturing since the bar codes are invisible to the human eye. The bar code~ may al~o be textured in the longitudinal direction instead of the vertical direction as shown. In either case, the bar code will be read in either direction along the longitudinal axi~ as long as th card is pa~sed in a direction transver~e (that is, not parallel) to the direc-tion in which the bars are textured, so long as a portion of each bar of the code is read.
Figure 2 is a representation of the playing card in which the face value of the card is not .hown, but only showing the disposition of another bar coding as phantom shaded portions along each of the four margins of the card.
Figure 3 is a representation of the playing card in which the face value of ~he card is not shown, but only showing still another bar coding as phantom shaded por~îons in discrete blocks across the entîre face, the code being alternated in longitudinal and vertical directions, ~ that the card will be read as long as a portion of ~he card passes over the electro-optical readiny mean~.
Figure 4 is a representation of a playing card, spe~ifically the two of spades, showing a portion o~ the textur~d bar coding in phantom outline, the bar aoding b~ing repetitively textured along the edges of the card.
Fig~re 5A is a plan view of khe rear~ urfaae of the lower lamina (base ~heet) depicting a fanciful printed de.~ign such as is found on a conventional playing card.
Fi~ure 5B is a plan view of the front surfa e of the base æheet depiGti~g a fully reflective alumini2ed or ~imilar sur~acQ which reflects light of æubstantially all wavelengths in the vi~ible, near~infrared, and near-ultra-: violet regions.
Figure 5C is a plan ~iew of the rear surface of the ~ 3/10870 PCT/US92J~9~

2 ~ 1 12 upper lamina (top sheet) depicting a fully visible~ ht-absorbing but infrared-transmitting surface of black ink on which is overprinted a bar code in colloidal carbon (India ink) which absorbs in the near-infrared region.
Figure 5D is a plan view representi~-the face of the two of spades, which like the other cards in th~ deck are printed in visible-light~absorbing printing inks, which face appears to be of a conventional card be ause the card stock does not noticeably show that the rear surface of the top sheet i~ blackened; but the blackened surface hides the bar code in colloidal carbon.
Figure 6 is a perspective exploded view schematically illustrating a laminated playing card made from only two, namely top and base ~heets, whîch when laminated appear to be conventional car~ stock~ a non~self-supporting inter-mediate layer consists of only tAe bar code deposited as solid particles of infrared absorbing mat~rial, preferably smaller than 44~m (microm~ters~ in average si~e, on the fxont surface of the base ~heet.
Figure 7 is a perspective exploded view schematically illustrating a laminated playing card in which the inter-mediate layer is a ~elf-supporting layer of refl~ctive material on which strips of infrared ab orptive material, such as colloidal carbon, are deposit~d in a bar code. ~he base ~heet i~ of conv~ntional stock about one~half as thick (~bout 5 mils) as conventional card stock ~about lO mils).
Figure 8 iæ a perspective exploded view ~chematically illustrating a laminate~ 2 of diamonds in which the inkermediate layer i5 a combination of a non-self-~upporting film of re~lective foil less than 0.5 mil thick on which is deposited a bax code of colloidal carbon~ and a self-supportlng film greater than O.5 mil thick which fi~ms together are ~andwiched between the upper and lower lamina~.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The preferred card reader comprises a housing which is a generally rectangular parallelepiped having a planar ~o g3/l0870 2 :~ 2 ~ 2 ~ :~ P~r/US92/09704 surface at least a portion o:f which i:; permeable (that is, transparent) to the wavelellgth to be used to read a playing card passed laterally over the surface, preferably in surf ace-to-surf ace contact therewith . ~ ~ypical ¢ard reader has a housing approximately 18 c:m long a~2 cm wide with a depth of about 4 cm. It will be readily apparent to one skilled in the art that the osrerall size of the hvusing may be shrunk substantially so that the area of the deck is .
comparable to that of a ~;tiandard piaying card, such shrinkage ~ntailing "surfac:e-mount" tec}lnology and an appropriat~31y c::ompact power source. The dagree to which such shrinkage is justified will be dictated by the ultimate cost of the devis::e~ Wi~hin the housing is mounted an elec:tro optical reading means havirlg an 'leye~' aimed directly upwards t~rough that portion of the platf orm which is permeable. The platform is preferably flat, but may be shaped to conf orm to cards OI arbitrary curva ure, or which are bent or curved in being passed in contact with the platform~ s surface .
2 0 In the be t embodiment the device uses eith~r an infra:red or ultraviolet source and matchlng detector and respoTIds to t~e dif f erences in ref lec:tivity and ab~;orptivi~y of the prepared, coded~ surfat::e, or intermediate layer, o~ each card. ~n the ultraviolet case, the aoded ~ura~ e, wh~3ther of the upper layer or the intermediate lay~r, may vary in either r~f lectivity or absorptivity, or in f luorescence . In the latter ca~;e, the detector would be ahosen lto respond to visible f luorescence I exc:ited Iby the ultraviolet. Thus it is seen that the 3 0 detector may be cho~en to respond to actinic radiation whether su~h radiatic~n is below 4000~ or above 7000 providQd that either the actinic radiation or the f luoresc:ence generated is essentially invi~ib~ e to the human eye.
3 5 Nore specif ically, Table I lists the various combina-tions of sources, appropriate detectors and the optical respon:~;e which is monitored.

WO 93/10870 Pc~/US92/~

- 212~ J~ 114 TABLE I
Source Detector C: p~ical response IR IR Dif f erential ref lectivity or long wav~length f luoresc::ence Vi~;ible IR f luore~;~anc:e W Visible f luorescence W W re:Electivity The readlng means f or the reader is mounted on a control board on the underside of which is also mounted a 10 microprocessor and other solid~state components. E~attery mean~; provide a convenient power source in the f orm of several sub C cells each .having a normal voltage of 1. ~5 volts. geys are operatively conn~cted to the solid-state devices on the control board to provide the ~unctions 15 de~cribed hereinafter in the f low charts ~
The solid-state elements which interac:t tt~ provide the above-described ~unctions includ~ a microprocessor ~ an erasable prQgramma3ble memory; a peripheral interf ace adapter whi ::h interfaces the reading means, an indicating ~20 means whic:h may be a ~peech processor or indicating lights positioned at 2as::h location to which the cards are ~-o be d~a:lt ,: ~nd the key~; . A IEirst multiple Schmidt trigger arld a ~3~rial shift.register converts raw light pul~:es to a dLigitzll word. A read-writ~ random~ access memory i~ u ed to ~25 sts:~re preset operating conditions~ ~Eor example, a :specific-ally t:hosen~ d~al.. A low current, reed-type relay controls powe!r-orl and power-ofî. An address :decg:~de d~terminas the arahi ecture of ~he memory. A ~econd multiple Sc:~idt I trigg~r jtogether with a resi~;tanc~-capac:itor netw~rk 30 d~texmin~s the operat1ng c:loc:k frequ~nc:y of the MPU
~microproces~or unit~.
Detail~; rela~ing to the foregoing will be found in the parent application, along with illustrative drawing~, more ful1y l;o understand ~he scope o~ the invention claimed 35 herein.

As ~hown in Fig l, the face o~ the 2~ (2 of spades) ~ WO93/10870 ~ f~ P~T/US92/09704 .

referred to generally by reference numeral 10, is marked with a bar code identif ied as the "card code" 11 consisting of spaced apart wide bars 12 and narrow bars 13, which bars extend from near one (upper~ longitudinal margin 1~ to the other (lower) 15. ~he bar~ run in a horizontal ~irection at right angles to the vertical axis of the card. A wide bar 12, in this illustration, represents the binary digit 1, and a narrow har 13 represents the binary digit 0. A wide bar is typically from 50% to about 300%, preferably 100%
wider than a narrow bar. ~he width of the spacing between bars is not narrowly critical provided it is at least as wide as a narrow bar. Each wide and narrow bar represents a zone of contrasting reflectivity relative to the back-ground t that is, the spacing between bars~ and the space around them.
By way of example for this specific illustration, four bit~ are used to identify the face value of the card, and two bits to identify the suit. A series of 8 bars makes one byte and ~ach card is uniquely identified by a combination of ix bits within t~e s~rie~, the other two bits being used to determine the orientation of the card being read, and to detect errors. To re~d the code in Fig 1, ~ome por~ion of each opposed longitudinal edge of the card must pa~ OV~E the reading m~ans. A c~rd code t ~ ically includes bar~ which allow the code to be read from eith~r direction along the lon~itudinal axis.
The following Table 2 represents each value of a card in a deck, in bin~ry form.

WO 93/1087Q YCI`/US92/09~"4 '~ 1 2 i~

Bit Card Value 0 1 1 1 1 1 0 0 0 ~ O` -û O

3 0 0 ~ 1 0 ~ 1 1 0 0 0 Q 1 0 1 0 1 ~ 1 0 1 0 o o 6 1 0 1 u The bar code is inklessly mar~ed by depositing miirro-scopic crystals having the same 'col~r' (white or off-white) as the background on which each of the bars is placed; the crystals may absorb in ~he near-infrared or the near-ultraviolet (O.~i~m 0.4~m~, depending upon which wavel~ngth is to be ~ead by t'h~ r~ader. Particle~ which ~absorb in the near ultravioIet are those of certain glassy : ~ mat~xials and inorganic and o:rganic salts. ~ar~iGles which , absorb in the n~ar-inf~ared are various alkali metal and ~0 alkaline earth met:al~ salts of fatty acids, for example , : . ~ calcium acetate~ and o her inorganic:and organic compounds.
Alternatively the:bar code may~ be marked by scuffing the:~urface~of~the ~ace of:the;~card~so~that the fiberæ of the card stock are~ dislodged suf~iciently o:absorb:or 25 ~ saatter in the desired~wavelength9 ~so as to contrast;in rsflec~ivi~y with ~h~e undisturbed fib~rs of the~background:.
:~ ; Such sc:uf~ing may be acc~omplished:with a fine wire brush or by blowirlg a stream of fin~ particles of an abrasiv~ across the card stock.
The card 0 (Fig 1~ will be read when passed across ~: the reading m~ans in either direction along lthe longitudinal axis, requiring that:two opposed~edges of the ~: : r~ctangula~ card travers th~ reading me~ns.
Figure 2 represents a variation for bar-coding a card :: 3S 20 with a co~e referred to by reference numeral 21, in ~ which each wide bar 22 and each narrow bar 23 is peripher-(~ ~O 93/10870 P~/US92/09704 ,~3 ~

ally continuous on i~t least two sides of the rectangle, and all the bars are spaced apart from one and another. Since the code is read by reading 8 bar~;, a set of bars to be read con6ists of four bars along two ~;ides of the 5 rectangle, and four bars from the opposed~émaining two sides of the rectangle. If bit 1 happens to be the same as bit 8, or bit 2 happens to be the ~;ame as bit 7, or bit 3 happens to be the same as bit 6, then the bar;
corresponding to those bits will have the same width along lû the entire periphery and appear as continuous. As before, the widlth of the ~;pacing of the peripheral bar:; must be at least as wide as the narrow bars~
The card ~0 (Fig 2~ will be read when passed across the reading means in any orientation, requiring only that 15 two opposed edges of the rectangular card traverse the reading means., Ref erring now to Fig 3, there is shown a card 3 a with yet another bar c:oding conf i~ration ref erred to by reference numeral 31~ in whic]h wide a~d narrc3w bars 32 and 20 33 respectively, similar to khe bar coding of Fig 1~ but on a diminish~d scale several times smal~ er than that c: f Fig 1, is reproduc:ed repetitively a plurality of times in adjac:ent, parallel relationship in two ad~acent rows. Each row ha~ the same set of 8 bars ~xcept that each contiguous 25 E:~t i5 rs:~tated ~OD ~rom the other. ~he card îs identified a~ long as any $et of 8 bax s in either row is passed over the re~ding m~ans. Thus the card will be read even if only two adjac::e~t edges o~ th`e card traver~e the reading means.
T~ei dif~erence in reflec:tivity read by the reading 3 0 mean~; determines whether the ~pace read contairlls a bit . The r~ading means can only distinguish between re~lective and non-ref le~tive portlons in the wavelength range vi~ible to the reading means . The reading means theref ore can use any wa~elength range which ~s either in the infra-red or in the 3 5 ultra~iolet, thP f ormer }: eing pref erred O
Ref erring to Fig 4 there is shown a card 4 0, specif ic-ally the 2~ in which the code 41 ~in phantom outline) is WO g3/10~70 PCr/US92/~97f`4 2 ~ ~ (i2 ~

textured along eac::h of the :Eour edges of the rectangle withou~ the wide and narrow bars 42 and ~3 respectively, substantially s:~verlapping the face markirlgs. It will be appreciated that when th y do overlap the f ace markings, ~i the bars will not be visible~ ~--The card 40 (Fig 4) will be read when passed across the reading means in any orientation, requiring only that one edge of the rectangular card traverse the reading means .
It will now be evident that the inks used to print th2 visible indicla (face values) o~ the cards should not be re~adable by the reading means, and the bright ;::olors used are generally infrared permeable. For example even black indi,c:ia such as the Ace of spades, which appears jet black to the human eye and would be expected to absorb in the infrared wavelength, can be printed in an ink which appears to be j et black to the human eye but does not absorb substantially in the infrared region~
An imprint of a bar cod~ which most pref erably abs~rbs in the infrared is obtained by depositing microscopic part-icles of powder, such as crystals from a solution O:e an inorganic salt suc::h as barium sul~ate, or a ~;olution of an organic salt such as sodium acetate, rather lthan an ink~
The particles are chos~n for their absorptivity of the wavelength of light used ~y the reader~ More preerably th~
bar code is obtained by etchirlg or texturing the surf ac:@ of th~ card with an abrasive powder c: r by ~nechar~ al msans so as to produce a code o~ ontrasting textures, ~he bar~
I being dU~Ll (tha~ is, infrared absorptive~ and leaving the spaces betweQn the bars, and the ba~kgro~ d shiray (that is, infrar~d reflective); or, less preferably, vice versa. In ~ither case I whether produced ~y a solution or by etching or texturing, a card is encoded with the bar s::ode without using an ink, i. e. inklessly~
In another embodiment, a dispersion or solution of inorgallic or organic particles used to produce the bar code may ~e chosen to f luoresce in the visible or infrared when .. . . . . . .. .. .. . ...... . . . . .. . . . . .

~0 g3/1~870 ~ Pcr/uss2/~s704 illuminated by ~an ~ppropriate UV light source, con~rasting with the space~ and background.
In general, a clandestine bar c:ode, namely one which cannot be read by the na}ced eye, may be textured into any S surface which already bears visible indic~, for example, a garment label, a ticket to a ball game, stoc:k certif icates, legal documents, bank drafts, checks and bank notes. Wher the code is textured, it will be readable by either an infrared or ultraviolet detection system, that is, in a 10 range outside the visible. When the surface to be coded is smooth, one has ~he option of providing either a textured bar code, or a code with ar~ invisible dispersion of dye or microscopic powder.
In the particular instance s:~f conveying printed 15 information in a predete~ined limited area, for example a printed page o text s the use of invisible solutions readable in the infrarad or ultravlolet may be used to incr~ase the density of text several fold~ For example, a page of s::onventionally printed text, printed in ink which 2 0 to the eye appear; j et black, :may be overprinted with an invisible olution which is readable in the in~rared; and again overprint~d with an invisible solution which is readable in 1;he ultraviolet . Thus ) the number of f orms vf texf: is limited only by the optical wavelength band width 25 of ~he det@ctor-~, the band width of the exc:iting radiation, and th~ responsivity of the inks or solutions, whether ab . orbers or ~luoresc:ers. In ~;ome instances, the inks or so~utions may not be ovexprinted one on top of the other, but within unprin~ed or blank space~ such as interllnearly 30 in a page of conventional text.
Tp~ Laminated ~layin5~ Card:
~ he laminated card may be read either with infrared or ultraYiolet light, as des~:ribed hereinabove. The following desc:riptiorl refers only to the use of in rared ligh~ to 35 read the c:ode because implementing details for making a card and reading it with ultraviolet light are signif icanltly dif f erent in exec:ution a~ compared to the WO 93/10870 PCI`/US92/0~4 ~0 details of ronstruction of the preferred embodiment described herein. Ir Referring to Fig 5A there is shown the rear surface 52 of the base sheet 51 of a card, which rear surf ace is 5 conventionally printed with a design 59. ,w~ren làminated to the top sheet 55 (Fig SC) the laminated card will appear to be a conventional playing card., To this end, the base sheet is only one-half as thick as conventional card stock. Fig 5B illustrates the front reflective surface 53 of the base 10 sheet 5~ . Fig 5C illus~rates the r~ar surf ace 54 of the top sheet 55, also made of half-thickne~;s corsventional playing card sto ::k, the entire rear surf ace 54 being covered with a spreadable medium such as infrared tr~nsmitting black ink.
In the best mode, a bar code 56 consisting of wide bars 57 15 and narrow bars 58 of infrared absorbing colloidal carbon (India ink) is conc:ealed within the playing card by printing the code on the blac]kened rear surface 54. The interlaediate layer consi~ts o:f the reflective surfac:e 53 and the bar code 56 on the blac3cened surface 54. Fig SD
20 il lustrates the white surface 57 o~ the face of the c:ard on top sheet 55 on which f ace the value o~ the card is designated .
When top and bottom sheet~; 56 and 51 are lamirlated the card appears to be a conventional card with a conventional 25 rear ~;urface 52 and a conventional face 57.
Ref~rring now to Fig 6 there is shown a card 60 (2~3 to be laminated from half-1;hic:k base and top sheets ~1 and 66 respec~ively in a mamler analogous to that described albove- The fa ::e 67 is printed conventionally and th~ rçar 3Q urface (not visible) of the op sheet 66 carries no code and is unmarked. The front surface 63 of the base sheet 61 carri~s only the code 66 textured with infrared ab~orbing ~ulid paxti ::les depo~ited in wide and narrow bars 67 and 68 re~pectively, as shc)wn, in at least one bar code c:onf igur-35 ation, but preî~rably repetitively. The front surface 63 ofl:h~ ba~e sheet is otherwise unmarked . The rear surf ace ( not seen) of the base shePt is printed with a conventional ~0 93/10870 ~ L~ P~/US92/097~4 design as shown in Fig 5A. The powder used for the bar code is not visible again~;t the surface of the half-thick card stock but absorbs in the infrared region so as to be read by the reader . The intermediate l~yer is theref ore only the 5 powder.
As illustrated in Fig 7, the card 70 consists of top and base sheets 75 and 71 of half-thidc c:ard stock, the front f ace 77 being white and carrying the f ace value ( 2 ~ ) of the card, the front face 73 of the rear sheet being 10 unmarked, and the rear face of the base sheet being printed with a desigrl as shown in Fig 5A~ The intermediate layer 72 i5 provided by a thin metal (alumimlm) or metallized f ilm which ref leclts essentially all the light f alling upon it .
Such a metallized intermediate ~ayer may be provided by any 15 conventional technique for applying a thin film coating, f or ex~mple, by vacuum deposition, spu~tering or electrolytic deposition. By "thin film" we refer to a thickness which is ~;uffic:ient to reflect ~ub~tantially all infrared and visible light Ialling upon it. A preferred 20 me~allized layer is provided by sputtering or va ::uum depositing aluminum, nickel, tin~, copper and the like. Most preferred i aluminum becau~;e of its high reflacîivity, lower initial opltic:al transmissivity and despite its t:endellcy to oxidi ~30 The conductivity of the metallized 2 5 layer is i~materia~ f or the purpo~e of thi~ invention, as the intermediate layer is substantially electrical}y in~:ulated by l:he upper layer and the base layer, eac:ll of whic:h is typically formed from insulating materials~ An lappropriate choice o~ a metal f or the ref~lectiYe 3 0 inltermediate layer ~ay be made by ref er~ncs to the teachings in the text a'Physics of Thin Filmsl' by J.
L . Vos~;en Vol 9, Academ.ic: Press, New York ( 1977 ) .
q~he code 76 is provided with eolloidal carbon as before in wide and narrow bars 77 and 78, pre~era~ly 35 repetitively, but at lea5t once. The code may al~;o be pro~rided ac:ross the transverse axis (orthogonal to the code shown), though the second code is not shown on the same Fig WO 93/10870 PC~/US92/~9f~4 2 ~

to avoid confusiollO In addition the code may be provided in any of the con~igurations shown in Figs 1 4 depending upon how much f lexibility of orientation is desired in reading the card.
The code being in carbon, a materia~ich~ also strongly absorbs in the visible, the bars are faintly visible through the top sheet through the l~ackground where there is no f ace ~ralue marked on the card . Instead of covering the rear face of the card with infrared tran~;mitting black ink, as before, the rear face of the top sheet is covered with a f inely divided white powder which ~;catter~ visible light. The fac:e 77 of the card thus appear~; highly re~lective and the bar code is effectively hidderl because light from the bar code doe~ not get transmi~ted through the front face 77 of the card.
If the code is provided :in a '~whitel' powder which is not visible against the norma:Lly ref lective white surf ace of the bas~ sheet, the code i~ hidden f rom view even when the card is held up and view~d against a strong light.
In ~ddition to hiding the aode fr~m human view, it is desirable to provide maximum contrast between the infrared-absorbing code and the ref lective surf ace against which it is read by the reader. It will be appreciated that a playing card is typically to be read by the elec:tro-optic m~an~ in the readex when a deck is to be dealt in normally bright ambient lighting such as is used in a large rc)om in which a bridge tournament i8 held. Thus, some of the visible light in the range from about 5% to 20%, falling on ; the "r~ader~' is transmitted through th~ top sheet (upper 3 0 layer) and i8 ref lected by the interlllediate layer, along with infrared light which the reader uses to read the code.
When substantially all the transmitted visible light or infrared light seen by thQ reading means is re~Elected by the intermediate layer which p~rforms a mirror-like fUTl tion ~except for those areas co~rered by the code3, the contrast between the coded areas where the infrared light was absorbed, and, the remainder of the f ield ( around the ~WO93/1n870 PCT/US92~097~4 J ~ a ~

bar code) o~ the intermediate layer which reflects both infrared and visible light, is diminished. This diminished contrast makes it difficult to read the bar code with an economical reading means.
It is therefore preferred to provid~rsprèa~able medium which functions as a selectively light-permeable auxiliary layer positioned between the bar cude and the rear face of the upper layer ~that is, the face of the upper lamina in contact with the intermediate layer). The auxiliary layer is permeable to infrared light but substan-tially impermeable to visible light which is either absorbed or scattered~
Such a selectively light-permeable auxiliary layer which absorbs and/or scatters visible light is essentially transparent to in~rared light. This auxiliary layer i~
provided by the black i~k commonly used in Papermate Flair brand pens. 5uch an i~k may be painted on the rear fa~e of the upper layer so that essentially no visible light will be transmitted through it. Instead of an ink~ a dye cr 29 paint having the same optical characteristics may be equally effective to serve the function of a thin, spreadabl~, selectively light-permeable medium.
Instead of covering the r~ar fa e of the upper layer with the spreadab~e, electi~ely light-permeable medium ~ink, paint or dye)0 the auxiliary layer may be spr8ad under the code on th~ intermediate layer. If the infrar~d-transmitting black i~k is used, the surface (befoxe tha sheet~ are laminated) which will appear uniformly black to i the human eye, when it ~the intermediate layer covered with the medium) i~ viewed in the visible spectrum.
: Though the rear face of the upper layer is seen to be black/ the face of the upper layer appears to be that of a ~onventional playing card. When the laminated playing card is Yiewed agalnst a bright liyht in the vi ible spectrum, the playing card appears to be a conventional card and the code on the intermediate layer is not visible to the human eye~

WO93/10870 ~ 2 i~ 2 i~ I PCT/US92/0~7~

To avoid -~sing an infrared~permeable ink, the auxiliary layer of spreadable medium may be a thin layer of visible~light-scattering par~icles. Such particles are microspheres necessarily having a diameter in the range from about 0.5~m to 0.6~m (micrometers) ~mmerciaIly available under the Scotch-Lite brand from 3M Company. Such a thin layer of microspheres may be deposited from a suspension in a suitable liquid. The specific size range of the microspheres is required to scatter ~isible light which is reflec~ed from the intermediate layer, and to allow infrared light having a wavelength in the range of about 0.8~m or higher, to be transmitted so as to increase th contrast of the code read.
When so scattered, the visible light cannot be seen by the reading means i.n the reader, and the contrast between ~he reflected infrared light (substantially all of which is tran~mitted through the ~preadable me~ium) and that absorbed by the bar code is increased.
It should be noted that Scotch-Lite microspher~s are routinely u ed in the paper industry to reflect substantially all the visible light which falls upon paper containing them9 In such a use (as a reflective material) the sizes of the microspheres are randomly ~cattered over a wid~ range with the specific intent of performing a mirror-function, that is, not transmitting any light, irrespectiveof i~ wavelength.
The high reflec~ivity of the inte ~ ediate layer provide~ ~rom 50% to 90~contra~t on the bar code pattern in the i~frared region, depending upon the re~lectivi y of the metallized layer and the effecti~eness of absorption or sc~t~er of the infrared permeable auxiliary layer, whether ink, paint, dye, or microspheres.
Re~erring to Fig 8 there is schematically illustrated a laminated playing ~ard BO in which the ba~e and top sheets 81 a~d 85 are of half-thickne~s card -~tock, as befor~, but the intermediate layer is formed by a combination of a non self supporting layer 82 and the self-f ~093/lOB70 ~ 3 ~ 1 PCr/llS92/09704 supporting layer 83. The layer 82 may be any reflectivefilm upon which the code 8~ is printed or otherwise deposited, amd the layer 82 is supported on the layer 83.
As bef ore the code may be provided in any one of the 5 numerous configurations referred to herei~n~5Ove. As before, depending upon the choice of material from which the code is produced, the rear surface of the top sheet 85 (the term "sheet~ ; used interchangeably with the term "layer"
herein) may or may not be covered with a visible light-10 absorbing and/or scattering auxiliary layer4 ~lternatively,the layer 83 may reflec:t visible light to the front face, and the layer 82 ~ransparent to visible and infrared ligh~.
The thickne~es of the combirled intermediate layer is ~mall enough to be substantially unnoticeable betweell the top and 15 ba~;e sheets.
The upper layer may be of any conventional material such as a pigmented or unpigmented substrate, whether paper or cloth, paper coated with a cured latex of ~ polymer, or a sheet of synthetic resinous m~terial, provided the upper 20 layer is substantially permeable to infrared (or ultravis~let lightl if it is u~;ed).
The base layer may be of any conventional material which may be the ~ame as that of the upper layer or different. The function of the base lay~r is mainly to 2 S provide a support f o:r the intermediate layer O The base layer may be permeable to all wavelengths, as would be a thin sh~et of clear glass, or opaque, as would be a sheet of metal gr~ater than 0. S mil thickl, Sinc:e the playing card 1 of this invsntion is to be read only face-down, by the 30 reader, the base layer 81 pro~,rides no optical function whether it is transparent or opaque~
IIowever, in the two piece laminated card (Figs 5A~5D
and Fig 6), the front surface of the base sheet itself provides a ref lective surf ace, or a support f or a more 35 reflective surface to re~lect both visible and infrared wavelengths. In Fig 7, the îront face 73 s:)f the base sheet 71 may be reflective when the intermediate layer 72 - - , WO 93/llOB70 PCI/IJS92/0~
~ 1 2 '~; 2 i~ ~

transmits visible and infrared light.
The components of the laminated card are preferably adhesively bonded together with an adhesive which i5 essen-. tially permeable to infrared light. Such an adhesive is S commonly available rubber cement, or the ~e in a commer-cially available solid glue stick. Most preferred is an infrared transmitting epoxy resin such as Epon 828 from Shell Chemical. When the intermediate layer is supported on a thin sheet of thermoplastic synthetic resin, for example 10 poly (vinyl c:hloride), the thin sheet may be thermally bonded to th~ base layer and to the upper layer dispensing with the use of an adhesive. l:n another embodiment, the re~r surface of the top sheet and the front sur;Eace of the base sheet may each be coated with a thermal ly bondable 15 rèsin which is essentially transparent to the wavelength absorbed by the indicia of the code.
It will now be evident tha1: the best mode for producirlg a coded playing carcl whic:h is visually es~;~ntially indistingui~hable from a convent~onal 2 0 rectangular playing card will depend in large part upon the ecollomics of manu~acturing the card, particularly with respec1: to the imprinting of the code on the card, and more particularly when he code is a textured code. Since the t@xtured code î~ invisible to the h~an eye but textured 25 only in the sense that the reader ~;ees it ~s being textur~d, the s~nsitivity of the ~lectro~opkic r@ading rneans of the rQader is a nec~ssary corl~id~ration with rsæpect to the c:hoice of ~ the degree of " u~f ing" required lor t:he or~anic or inorganic c:ompound used to absorb 30 wavelengths to be read by the r~adîng meansO
For axamE~le, the non-laminalted card may ~e made by takirlg a convantit)nal playing c:ard and micro~:~opically scuf f ing its surf ace with a f ine wire brush so that the disrupted f ibers are essenti~lly invisible to the human 35 eye. Alternatively, mic:roscopic 501id particles of a compound ~hich transmit visible light, but substantially absorb in the infrared or ultraviolet ranges (depending ~WO 93/10~70 PC~r/US9~/09704 J ~ 1 ~7 which one is u~ed for the reading means) may be coated with an adhesive which transmits visible light, and the particles deposited on the card's surface, either across the entire f ace, or only near the margins, leaving the ~i remainder of the card'~ printed face unco~ t, a~ described hereinabove. 5till another alternative is to s:~ode the face of a c::ard with a solution of an organic dye which transmits visible light (therefore has no pigmellting value), but substantially absorbs in the infrared or ultraviolet 10 ranges.
It will now be eviderlt that though the face values of the card are conventionally printed in visible light absorbing inks, the inks chosen may not be conventional sinc:e they must al~;o be subst;3ntially permeable to ~he 15 wavelengtn used by the reading means to read the code, particularly if the code is imprinted over the f at::e values of the cards, as is the case .in some embodiments of the non-laminated card; and, is the case in all embodimeFlts of the laminalted card. This requiremQnt of the ink~; to be . used can only be arrived at after one has decided that the card is to be coded a~ de~cribed hereinaboYe. Further, producing a laminated playing card can only be arrived at after one has decided that the indicia of the card is to be placed behind the ~ront ~urface of the conventionally printed card.
~ he laminated card is preferably mad~ by starting with two nearly opa~ue ~heets (top and ba~e) o~ white card ~to~k each ~heet being about h~lf the thickne~s of conventional card stoçkO The outer (when the card is laminated) ~urfaces of the card ~tock to b~ printed with the face v~lues of the cards and the fanciful decorative design on the rear, may be '~inished~ differently from the inn~r surfaces~ In the most preferred embodlment of the method which result~ in a playing card described in Figs 5A-SDI the top and base sheets are each at lea5t large enough to print one deck of at least 52 cards. The entire rear surface of khe top sheet i8 coated with infrared-transmittiny black ink. The entire WO 93/10870 PCI/US~2/09~"4 2 ~ ~ Q~ 2 `~

front surface of the base sheet is reflectorized with a coating of aluminum eit~er by depo iting it directly on the surface, or by bonding an aluminized sheet of Mylar polyesterD Then the bar code is printed or otherwise 5 deposited on the alumina, and the top and~ase sheèts, with the aluminized sheet therebe~ween, are adhesive~y bonded together with thin layers, less than about 13,um thick, of an infrared-transmittlng epoxy resin. All layers of the card are t~us adhesively bonded together to f orm a large lO laminated sheet, and the large laminated sheet is then printed wîth the face values of the cards ~ then cut into indi~ridual cards of a deck.
I n an alternative method, micrc)scopic parti~::les of an infrared absorbing ccmpound are coated with an adhesive and 15 depo~i~ed on either the rear surface of the top sheet which have a sufficiently reflective surface, or, the front surf ace of the base sh e~, in the desired code conf iguration f or eac:h card . Th~ top and base sheets are then adhesively bonded together with an infrared-20 tranP:mitting as~hesive to form a laminated ~heet, and thelarge laminated sheet is then printed with the face values o~ the cards j then c::ut into individual cards OI a clec}c.
Altern23t~vely ~ the powder particles are coatsd with a .
thermoplastic resin and deposited in a desir d c:od~ on~ig-25 uration as described on either the rear ~urfac:e of th~ topsheet or t;he ~ront surf ace of the base she~t . The sheet is th~3n haated to a temperature above th~ glass transition ~elapera~ure or . mel ing point of th~ thermaplastic: resin so , that the particles are bonded to the sur~ace of the sheet.
3 0 The top and ba~;e sh~ets are then adhesively bonded together so ~s to app~ar like a ~heet of c:onventional ~::ard stock which is then printed with inf rared-transmitting inks .
In still another embodiment, the rear ~;urf ace of the top sheet and the f ront surf ace of the base æheet are each 3 5 coated with a thirl layer less than 13,um thick of a f irst in~rar~d transmittillg thermoplastic resin. A self-supporting layer of a reflectorizPd (aluminized) second ~WO~3~10$70 ~ 12 1~ ~1 PCT/USg2~09704 .

thermoplastic resin having a glass transition temperature no higher than that of the first resin, i~ imprinted with the desîred code. The self-supporting coded layer is ~andwiched between the coated surfaces of the top and base sheets and heated under pressure until b~ she`ets are thermally bonded to ~he self-supporting layer. The laminated large sheet so formed is then printed with the face values of the cards, as described, abovP~ and cut up into individual cards of the deck.
~aving thus provided a general discussion 9 described the playing card in detail, and other standardized documents generally which documents could be constructed using the teachings herein, and having illustrated the specific embodim~nt of the playing card with specific examples o~ the bes~ mode of making and using it, it will be evident that the invention has provided an effective and economical solutlon to a difficult problem. It is therefore to be understood that no undue res~riction6 are to be imposed by reason of the speci~ic embodiments illustxated and di~cussed, except as pro~ided by the following claims.

Claims (27)

1. A rectangular playing card from a suit in a deck of playing cards, each card being a single sheet of non-lamin-ated card stock, said card having (a) a substantially white surface conventionally printed with the identification of the suit and value of the card with visible inks substantially transparent to wavelengths outside the visible range, and, (b) indicia inklessly marked across said surface with a compound which absorbs wavelengths outside the visible range, said indicia corresponding to a code which uniquely identifies said card, said indicia being essentially invisible to the naked human eye, but readable by an electro-optical reading means sensitive to light outside the wavelength in the visible range from about 4000 .ANG. to 7000 .ANG., whereby said inklessly coded playing card is essentially visually indistinguishable from a conventional playing card.

2. The playing card of claim 1 wherein said inkless code is defined by contrasting textures of said indicia against said card's face.

3. The playing card of claim 2 wherein said inkless code is defined by contrasting absorptivity and reflectivity of disrupted fibers of said card stock compared with fibers which are not disrupted.

4. The playing card of claim 2 wherein said inkless code is defined by contrasting absorptivity and reflectivity of a dispersion or solution of a compound having essentially no pigmenting value.

5. The playing card of claim 3 wherein said inkless code is textured with microscopically scuffed indicia invisible to the human eye against a background of said card's unscuffed printed face.

6. The playing card of claim 3 wherein said inkless code is textured with microscopic particles of powder defining said indicia which are invisible to the human eye against a background of said card's printed face.

7. The playing card of claim 4 wherein said solution is an organic dye which is invisible to the human eye against a background of said card/s printed face.

8. The playing card of claim 1 wherein said indicia are in the form of a conventional bar code having spaced apart wide and narrow bars.

9. The playing card of claim 8 wherein said wide and narrow bars of said bar code are peripherally continuous on at least two sides of said rectangular card, and all the bars are spaced apart from one and another.

10. The playing card of claim 1 wherein said indicia are repeated across said card's entire printed face.

11. The playing card of claim 1 wherein said indicia are repeated along only the edges of said card leaving the printed face of the card uncoded, whereby said card is adapted to be read by said electro-optical reading means when any portion of said card is passed over said reading means in any orientation in a lateral plane.

12. The playing card of claim 10 wherein said indicia are disposed in adjacent, parallel relationship in two adjacent rows, each row having the same set of 8 bars except that each contiguous set is rotated 90° from the other, whereby said card is identified as long as any set of 8 bars in either row is passed over aid reading means.

13. A playing card comprising, an upper lamina or top layer having front and rear surfaces, said front surface of which is imprinted with the face value of the card with inks which absorb and reflect wavelengths in chosen ranges corresponding to colors characteristic of said playing card, said inks being selected to be transparent in the range of infrared or ultraviolet wavelengths chosen for absorption by concealed coding indicia; and, a lower lamina or base layer having front and rear surfaces;
said inks being printed on said upper surface of card stock which reflects substantially all light in the visible spectrum, and transmits rather than reflects substantially all infrared or ultraviolet light used to read said coding indicia; and, said coding indicia disposed between said upper and lower laminae being provided with a compound which absorbs substantially all infrared or ultraviolet light transmitted through said upper lamina, said compound being deposited between said upper lamina and lower lamina before they are bonded together, whereby said coding indicia are adapted to be read by a device using light in a predetermined wavelength in the infrared or ultraviolet wavelength ranges to which said upper lamina is permeable, said predetermined wavelength being selectively absorbed by said coding indicia but reflected by the remaining area of said base layer.

14. The playing card of claim 13 wherein said rear surface of said upper layer is coated with a coating which absorbs or scatters visible light.

15. The playing card of claim 13 wherein said front surface of said base layer is coated with a coating which reflects essentially all light not absorbed by said coding indicia.

16. The playing card of claim 14 wherein said rear surface of said upper layer is coated with said coding indicia.

17. The playing card of claim 16 wherein said coating is a black ink and said compound is colloidal carbon.

18. The playing card of claim 17 wherein said front surface of said base layer is an aluminized surface.

19. The playing card of claim 13 including an intermediate, selectively light-reflective layer imprinted with said coding indicia which absorbs in the infrared region from about 800-104 nm, said intermediate layer being sandwiched between said upper and lower laminae, said intermediate layer reflecting essentially all light transmitted through said upper layer, whereby said coding indicia imprinted on said intermediate layer are adapted to be read by said device.

20. The playing card of claim 19 wherein said rear surface of said upper layer is coated with a coating which absorbs or scatters visible light.

21. The playing card of claim 13 including an intermediate selectively light-reflective layer imprinted with said coding indicia, said intermediate layer being sandwiched between said upper and lower laminae, said intermediate layer reflecting essentially all light trans-mitted through said upper layer and not absorbed by said coding indicia;
whereby said coding indicia imprinted on said inter mediate layer are adapted to be read by said device.

22. The playing card of claim 13 including an intermediate selectively light-reflective layer imprinted with said coding indicia, said intermediate layer being sandwiched between said upper and lower laminae, said intermediate layer transmitting essentially all light transmitted through said upper layer and not absorbed by said coding indicia; and, said front surface of said base layer is coated with a coating which reflects essentially all light incident thereupon;
whereby said coding indicia imprinted on said intermediate layer are adapted to be read by said device.

23. The playing card of claim 13 wherein up to 20% of said light in the visible spectrum is transmitted through said top layer.

24. The playing card of claim 19 wherein said intermediate layer is coextensive with said upper and base laminae.

25. The playing card of claim 21 wherein said intermediate layer is coextensive with said upper and base laminae.

26. The playing card of claim 24 wherein said base layer is opaque.

27. A method for making a laminated playing card, comprising, positioning first and second sheets of card stock of about equal dimensions, each about 5 mils thick t said first sheet having a front surface to be printed with insignia for the face value of said playing card, and said second sheet having a rear surface to be printed with a design, coating said first sheet's rear surface with a coating which absorbs or scatters visible light but transmits in the infrared region, depositing machine-readable coding indicia on said rear surface, coating said second sheet's front surface with a reflective coating, adhesively bonded together said first and second sheets in coated surface-to-coated surface contact with an adhesive which is substantially permeable to wavelengths in the infrared region, to form laminated card stock, and, printing said front surface of said first sheet with said insignia in inks which absorb and reflect in the visible range to produce characteristic colors of said insignia but which inks are substantially transparent to wavelengths in the infrared region.