Optical record cards

Abstract: An optical information storage card having a rectangular format, said card comprising: a substrate having, on at least one side thereof, surface relief formations forming an optically machine readable information surface; and, a protection layer being in overlying juxtaposed relationship to said information surface; said substrate and said protection layer being transmissive to a selected range of electromagnetic radiation usable for optically reading said information surface; said information surface having a generally spiral and/or concentric format whereby said information surface can be read as said card is rotated about at least one axis.

Description: This invention relates generally to optical information storage cards and, more particularly, to optical information storage cards of wallet size having optical media integrally formed therewith, which are encoded and encodable with machine readable code. In the information society of today need exists for storing and, of course, retrieving information in a manner which provides rapidity, low cost, reliability and which is condensed for economy of storage. It is expected that this need will be, in part, met by information storage cards such as bank, medical record, and the like which will have high-capacity data storage features and can be carried in a wallet. Furthermore, it is desirable to write information on the cards subsequent to their being issued. Such features add measurably to the versatility of these cards. Additionally, it is desirable to have such cards constructed in such a manner that they can be read and/or written on simply and expeditiously. With the relatively recent progress in optical recording techniques, optically encoded and/or encodable media are preferred in many situations because they can store significantly higher amounts of information than, for example, correspondingly sized magnetic media. Such storage capacity is preferable in situations where digital image storage is contemplated, such as in medical storage or record cards. A wide variety of optical recording media and optical storage cards already exist. Representative examples of such media and cards can be found in United States Pat. Nos. 3,647.275; 3,858.032; 3,894.756; 4,007.462; 4,023.185; 4,066.873; 4,150.781; 4,230.939; 4,298.975; 4,360.728; 4,500.777; 4,503.135; 4,508.811; 4,510.232; 4,542.288; 4,543.225; 4,544.181; 4,616.237; 4,663.518; WO-Publ.No. 86/05620; JP-Publ.Nos. 61-016045; 62-264458; 60-127543; 62-209785; 59-011552; 61-190721; EP-Publ.No. A-0 230 069; and "Principles of Optical Disc Systems", G Bouwhuis et al, 1985, Adam Hilger Ltd. EP-A-0 230 069 discloses an optical information storage card having on one side thereof a circular track for retaining read-only information, the track being constituted by a reflective tellurium alloy data layer embedded in the card and covered by a transparent protective layer. WO-A-86/05620 discloses a storage card carrying a narrow annular information surface area which is comprised of a transparent base layer provided with surface relief formations, covered by a thin reflective layer and an overlying protection layer. The surface relief formations provide machine readable tracking information, when read through the transparent base layer in a reflection mode. The thin layer is writable by high-power laser beams which burn holes or change the phase, structure, color, or interference properties of the layer, and can be magnetically or optically erasable, thus providing machine readable write-once or erasable information. It has to be noted that the tracking information surface and the writable information surface are presented by different layers, i.e. the former by the substrate and the latter by the superposed recording layer. It is not contemplated to present both read-only and writable information areas by the same material layer. JP-A-61-50683 describes an information storage card which has, for facilitation of information selection, on one face a photograph printed thereon and on the other face a plurality of optically readable parallel tracks. The photograph is printed in a conventional manner. Recording of the picture and of the track information requires different manufacturing processes. In "Video disc mastering and replication", by P. Palermo et al, Optics and Laser Technology, August 1977, p. 169, as well as in JP-A-61137241, the production of optical information tracks is disclosed by embossing of plastic substrates. Reference may be made to these documents for details of the embossing technique in general. SUMMARY OF THE INVENTION In accordance with the present invention, provision is made for improved optical information storage cards which feature both read-only and writable information areas on one card and are easy and economically to produce. According to the invention provision is made for an optical information storage card having a rectangular format, said card comprising: a substrate having on at least one surface thereof an optically writable textured information surface having a predetermined pattern which is strongly absorbent of at least a predetermined band of wavelengths of incident writing electromagnetic radiation and which may be written on through physical distortion of said predetermined pattern by such radiation, and at least one set of optically read only surface relief formations constituting read only information which facilitate optical machine reading of the substrate; and, a protection layer being superposed over said optically read only surface formations, said protection layer covering gaps over said textured surfaces; both said substrate and said protection layer being transmissive to electromagnetic radiation used for optically reading said relief formations and said writable surface; said substrate forming said textured surface and said relief formations being defined by a common sheet material having both said writable and read only information surfaces embossed thereon. In another embodiment of the invention there is provided an optical information storage card having a rectangular format capable of being carried in a wallet, said card comprising: a substrate having on at least one surface thereof an optically writable textured information surface having a predetermined pattern which is strongly absorbent of at least a predetermined band of spectral wavelengths of incident writing electromagnetic radiation and which may be written on because of physical distortion of said predetermined pattern by such radiation, and at least one set of optically read only surface relief formations constituting read only information which facilitate optical machine reading of the substrate; a first layer in superposed relationship over said relief formations, said first layer being made of reflective material to the predetermined band of wavelengths of the reading radiation; and, a protection layer superposed over said first layer, said protection layer covering gaps over said textured surfaces; at least one of said substrate and said protection layer being reflective to the electromagnatic energy used for optically reading said writable and read only surfaces, said substrate forming said textured surface and said relief formations being defined by a common sheet material which has both said writable and read only surface embossed therein. Among other objects of this invention are, therefore, the provision of an optical information card as laid down in claims 1 and 6. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an optical card made according to the present invention; FIG. 2 is an enlarged and fragmented cross-sectional view of an embodiment of an optical card; FIG. 2A is an enlarged and fragmented cross-sectional view of another embodiment of an optical card; FIG. 3 is an enlarged and fragmented cross-sectional view of yet another embodiment of an optical card; FIG. 4 is an enlarged and fragmented cross-sectional view of an embodiment of an optical card of the present invention; DETAILED DESCRIPTION FIGS. 1-3 illustrate several embodiments of optical information storage cards. Figure 4 illustrates an embodiment of an optical information storage card according to the present invention. Each card is, preferably, the size of most wallet size card formats, for example, about 85mm long and 54mm wide. Such a rectangular size has been found to be convenient for not only wallets, but also automatic teller machines and the like. Of course, this invention encompasses other suitable sizes (e.g. 82mm x 59mm) and shapes for optical storage cards of the overall kind contemplated. As shown in FIG. 1, a card 10 made according to this invention has an annular band A of machine readable data tracks (not shown) which can be optically read by a suitable optical reading device (not shown). In some embodiments, the annular band A can also be encoded with digital or analog machine readable information subsequent to issuance of the card 10. While certain of the embodiments speak in terms of a single annular band, the present invention contemplates others, not only on one side of the card, but on the other side as well. Reference is made to FIG. 2 wherein there is illustrated an enlarged and fragmented cross-sectional view of a simple laminar card structure which is intended for the transmission reading mode. The card 10 includes a substrate 12 which can have a thickness in the range of from about 1/2 to 50 mils (1.27x10⁻⁵-1.27x10⁻³ m), but about 30 mils (7.62x10⁻⁴) is preferred for total wallet size credit card thicknesses. In this embodiment, however, the thickness of the substrate 12 is about 15 mils (3.81x10⁻⁴ m). The substrate 12 is made of material which is transparent to the range of electromagnetic energy that will be used to read embossed information. The substrate 12 is made of a clear homogeneous polycarbonate material, such as LEXAN, a polycarbonate manufactured by General Electric. In this case the polycarbonate substrate 12 is embossable and transparent to electromagnetic radiation in the visible range. The optical reading can be performed by conventional lasers having suitable power. However, the substrate 12 need not be transparent to visible light, but can be transparent to radiation in the non-visible range, for example, in the near infrared zone. Other embossable materials can be used such as, polyesters like polyethylene terephthalate. These other embossable materials include polypropylene; polystyrene; vinyl; acrylic; cellulose acetate butyrate; polyesters; thin metals such as aluminum;and electron beam and ultraviolet curable polymers and epoxy-type polymers. The foregoing recitation of embossable materials is intended to be in no way limiting to the scope of the present invention. Embossed on a surface of the substrate 12 is a pattern of varied surface relief formations in the form of grooves or pits 14 shown diagrammatically in crenelated form. The grooves or pits 14 are of the type which provide a machine readable digital information surface 16 which is optically readable by a laser type optical system that reads changes in optical phase or transmission between such grooves or pits 14 and the surrounding surface of the substrate 12. For purposes of illustration, the grooves or pits 14 can range in depth from about .05 µm to .15 µm. Preferably, however, grooves or pits 14 having an average depth of .10 µm can be used. Pit lengths from about .6 µm to 10 µm and widths from about .4 µm to 1.5 µm are typical. It will be appreciated, of course, that instead of pits, surface protrusions suitable for optical reading may be used. The embossing of such an information surface 16 is accomplished by embossing the substrate 12, while the latter is part of a web, with a master die having a pattern with a relief structure which is the negative of that of the embossed information surface 16. Details of the embossing technique, per se, do not form part of this invention. Reference is, however, made to United States Pat. No. 4,543,225, for describing a web embossing technique which can be used in the formation of the information surface 16 on the substrate 12. This invention contemplates other web embossing techniques or other known techniques for forming such depressions such as injection molding or casting. It will be appreciated that the information surface 16 is physically integral with the structure of the card. This offers significant advantages including reduced manufacturing costs. This embodiment has described a one substance substrate 12. However, the substrate 12 can be made of several layers. Reference is made to FIG. 2A which shows a substrate 12′ having a 3 mils (7.62x10⁻⁵ m) thick layer 12′a of polyester which can have laminated to a surface thereof an embossable layer 12′b of cellulose acetate butyrate (CAB) having a thickness of about 0.5 mils (1.27x10⁻⁵ m). Thus, the total thickness is about 3.5 mils (8.89x10⁻⁵ m). The polyester layer 12′a will provide the requisite mechanical strength and pliant characteristics needed for a wallet size card whereas the embossable layer 12′b will provide the information layer. If desired in such a multilayered structure, a suitable subbing layer (not shown) may be provided between the polyester layer 12′a and the cellulose acetate butyrate layer 12′b. Reference is now made back to the embodiment of FIG. 2. Although this embodiment discusses an embossed digital information surface 16, it will be appreciated that the surface can have analog information embossed therein. In this embodiment, the machine readable information surface 16 is embossed such that the information data tracks (not shown) are.arranged in circular and/or spiral fashion. Accordingly, the optical card 10 can be read as it is being spun about a rotational reference axis extending through the plane of the card. The benefit of having data tracks arranged in such a fashion is that it can be used in conjunction with a relatively inexpensive optical card read system described and claimed in commonly assigned and copending application Serial No. 050,039 filed May 15, 1987 and entitled "METHOD AND APPARATUS FOR FEEDING CARD." Overlying the digital information surface 16 is a protection layer 18. In this embodiment, a relatively thick sheet of, for example, clear polycarbonate is used to add strength and protection to the optical information card 10. The protective polycarbonate layer 18 can have a thickness of about 15 mils (3.8x10⁻⁴ m). Polycarbonate of such a thickness has been found to be suitable insofar as it is sufficiently durable and wear resistant for normal card usage. This invention contemplates several alternative materials for such a layer 18. Besides using polycarbonate for the layer 18, it will be appreciated that other polyesters, such as polyethylene terephthalate can be used, as well as materials such as, polyvinyl chloride; polystyrene; an acrylic resin, such as poly(methylmethacrylate); and other suitable materials may be used. It should be readily understood that the thickness of the wallet size optical card contemplated is about 30 mils (7.62x10⁻⁴ m). Thus, the thicknesses of the substrate 12 and the layer 18 can vary. For example, in connection with FIG. 2A the thickness of a protective polycarbonate layer (not shown) could be about 27 mils (6.86x10⁻⁴ m). Alternatively, the layer 18 could be about 3.5 (8.8x10⁻⁵ m) mils thick and the substrate 12 could be about 27 mils thick. In situations where a thin lacquer or thin UV protector are used for the layer 18, the carrier substrate 12 would have to be correspondingly thicker than the previously noted 5 mils (1.27x10⁻⁴m) so as to provide the requisite strength and durability needed for the card 10. It should be understood that the thickness dimensions are a function of many factors. It will be noted that whatever combination of thicknesses the layer 18 and the substrate 12 have they should be approximately equal in sum to the recommended thickness used for most wallet size credit cards and the like. Of course, since the card 10 of this embodiment will be read in transmission, these other materials must be optically transparent to the laser being used for reading. The layer 18 is adhered to the substrate 12 by means of a layer of conventional optical adhesive (not shown), such as Lamal which is available commercially from Morton-Thiokol. The techniques for applying such adhesives are known, and the laminating of the layer 18 to the substrate 12 can be done using conventional procedures. In the case where both the substrate 12 and the layer 18 are made of polycarbonate, they have the same indicies of refraction. Thus, the layer 18 contacts the substrate 12 so that there are air gaps 19 formed over the depressions or grooves or pits 14, such as shown in FIG. 2, thereby allowing an optical read system to read the information surface 16 in the transmission reading mode. Air gaps 19 are not needed in the transmission mode if the substrate and layer have sufficiently different indices of refraction. Instead of air, of course, the gaps could be filled with, preferably, gaseous material having a sufficiently different refractive index than the substrate and the protection layer. Reference is now made to FIG. 3 for illustrating another embodiment of an optical information card 20. Unlike the previous embodiment, the present card 20 can be read in the reflection mode. Towards this end, a reflection layer 22 is provided so as to overlie an embossed information surface 24 defined by the grooves or pits 25 and the surrounding surface area. Because of the reflection layer 22, of course, the information surface 24 can be read with a reflected laser read beam of an optical reading head (not shown). The information surface 24, a substrate 26 and the protection layer 28 are of the same materials having the same characteristics and made in the same manner as noted above in connection with the corresponding layers of the embodiment shown in FIG. 2. Of course such materials and characteristics thereof can also vary according to the considerations mentioned above. Since the card 20 will be read in the reflection mode, specular reflector materials can be used. In this embodiment the reflection layer 22 is juxtaposed the information surface 24. Of course, it will be appreciated that the card 20 can be read in a reflection mode from either side of the card which is not opaque to the reading radiation. The embossing may be done before or after metalizing the information surface 24. This embodiment contemplates having the card 20 read in the reflection mode through either the substrate 26 or the protection layer 28. The reflection layer 22 can be applied in a variety of known ways, for example, by solvent means or vacuum deposition subsequent to the embossing procedure outlined above. In one embodiment, the reflection layer 22 is a metalized layer of aluminum which is applied through a conventional vacuum deposition technique which does not form part of the invention. The reflection layer 22 should have a thickness capable of achieving the foregoing reflecting function in the reading mode. For purposes of illustration and not limitation, the thickness of the reflection layer 22 can be in a range of from about 10 nanometers to hundreds of nanometers. In this embodiment, the thickness is 60 nanometers. Materials besides aluminum, of course, can be employed for reflecting all or part of the laser read beam so that changes in reflectivity of the information surface 24 can be optically read. For purposes of illustration, these other materials include, but are not limited to copper, gold, suitable alloys, dyes, etc. of comparable reflectivity. If the protection layer 28 is to be a thin layer of lacquer, it will be applied, of course, through conventional coating procedures. If the protective layer 28 is thicker, such as is the case in this embodiment, it would be bonded to the information surface by adhesives of the kind noted above in connection with FIG. 2. Also there is no need for air gaps since the card 20 will be read in a reflection mode. Thus, the protection layer 28 is brought into intimate and continuous engagement with the reflection layer 22 in a conventional lamination process or the like. Reference is now made to FIG. 4 to illustrate an embodiment of the present invention. In this embodiment, there is illustrated an information storage card 30 of the type which can be optically written on subsequent to issuance of the card. The card 30 includes an embossed information substrate 32 which can be made of a heat sensitive material, such as polycarbonate or polyethylene terephthalate, as well as the kinds of materials mentioned in United States Patent No. 4,366,235. Prior to the embossing, the plastic must be softened by either heat, pressure, solvent or some combination of these as is known in the art. In this embodiment, the substrate 32 is made of polycarbonate and has a thickness in the range of the substrate in the first embodiment (e.g., 3 to 50 mils) (7.62x10⁻⁵ m - 1.26x10⁻³ m). The polycarbonate is transmissive to the read and write laser energy to be used. The information substrate 32 has on selected portions thereof an embossed read only pattern and an embossed optical write-once textured pattern. By textured pattern it is meant that there is formed a microstructure array of embossed patterns of filaments or cavities which can have an ordered arrangement or a random arrangement. In this application a predetermined textured pattern shall be inclusive of both ordered and random patterns. A textured pattern is one which when subjected to, for example, laser energy of predetermined wavelength and intensity will cause a physical deformation or a structural relaxation to the pattern which allows the changed structure to be read optically either in a transmission mode or a reflection mode. Accordingly, a single embossing step can economically provide a versatile information substrate or layer which allows the card 30 to be optically written on subsequent to having been encoded. Towards this end, the information substrate 32 has selected areas thereof embossed with encoded surface relief formations or information grooves or pits 34 shown diagrammatically in crenelated form. The embossed information pits 34 will be for use in machine read only form that will be read by, for example, a laser head system using a predetermined band of spectral wavelengths of electromagnetic radiation. The surface relief formations 34 are, preferably, in a generally concentric and/or spiral format so that they can be read when the card 30 is rotated. Embossed optically writable textured surfaces shown diagrammatically at 38 are provided on other selected areas of the information substrate 32 and are also arranged in an annular format. The textured surfaces 38 comprise a predetermined pattern of embossed concentric and/or spiral grooves. The present invention contemplates arranging the read only information pits 34 and the grooved writable textured surfaces 38 in different formats. For example, the card can be provided with sectors like those on a magnetic disk, comprised of the read only information pits. The areas in between these sectors would be generally formatted and include the writable textured surfaces. Also, preformatted or pregrooved spiral tracks 35 are provided in the substrate 32 as surface relief formations which could include the textured surfaces 38 while the areas surrounding the tracks 35 would be smooth non-textured surfaces. Alternatively, the textured surfaces 38 could be placed adjacent the tracks 35. It will be understood that whenever the textured surfaces are used, they should be provided with an air gap 36 so as to allow the structural deformation to occur when the textured surfaces 38 are struck with incident writing radiation. Also as shown in FIG. 4, there can be provided a plurality of wide channels 39 (only one shown), each of which contains a plurality of smaller grooves 34′ with textured surfaces 38′. The surfaces 38′ can be formed in a manner as noted above. For purposes of illustration, the channels 39 can each have a depth dimension in the order of about 1/2 to 20 microns with a width varying from about 2 to 100 microns. The grooves 34′ can have depth dimension in the order of about .05 microns to .15 microns. Of course air gaps 36 would be provided over the writable medium of the type just noted. The specifics of the textured surfaces which can be used to produce a writable embossed layer does not, per se, form an aspect of this invention. Textured surfaces like those described in greater detail in the last noted patent and those described in an article written by W. Dennis Slafer and James J. Cowan and published by the Society for Imaging Science and Technology in the Journal of Imaging Science, Vol. 31, No. 3 May/June 1987 can be employed. The present invention also contemplates in some instances providing the textured surfaces 38 with an overlayer (not shown) to enhance the energy efficiency of the laser used for writing on such surfaces. The textured surfaces 38 are highly absorptive of incident writing electromagnetic radiation within a predetermined band of spectral wavelengths. In this embodiment, the absorption of radiation of a laser writing beam at the textured surfaces 38 causes observable physical changes in the heat sensitive polycarbonate to distinguish them from other regions which are not locally heated. In this embodiment, the optically written on surfaces 38 will be read in a reflection mode by subjecting the card to an optical reading beam. Reading can be performed by observing changes in reflectivity of the textured surfaces by using a power and/or wavelength which is not significantly absorbed. In this manner, there is no unintentional writing on the information substrate 32. If reading in reflection is desired, then a reflective metal layer 37 is placed over the read only pits 34. This invention contemplates that the textured surfaces 38 can be read in transmission. If the card 30 were to be read in a transmission mode, then there would not be need to place the reflective coating 37 over the information pits 34. If polycarbonate were to be used for the protection layer 40, then an air gap (not shown) would be provided over the grooves or pits 34 or even the tracks 35. Overlying the information substrate 32 is a protection layer 40. The layer 40 may be made of polycarbonate which is transmissive to the spectral range of the read and/or write laser beams being used and the thickness is about 27 mils (6.86x10⁻⁴ m). Besides an air gap, other preferably gaseous materials having different indices of refraction than polycarbonate can be used. Besides polycarbonate other suitable materials may be used, such as those noted above in connection with the embodiments described in conjunction with FIGS. 2 and 3. The kinds of optical adhesives usable for joining the protection layer 40 to the information substrate 32 can be similar to those discussed above in relation to the embodiments described in FIGS. 2 and 3 or can be others selected so as to achieve the noted adhering and optical functions. All the foregoing embodiments of the optical information card can have additional layers (not shown) as is known in the art, for example, a subbing layer to improve adhesion, an antiabrasive top coat layer (not shown) or other auxilary layers can be added to the foregoing constructions for example, holograms, photographs, magnetic recording media. Suitable subbing or compatibility layers would of course be used with this latter group of materials and layers as it is consistent with conventional practice regarding them. Also, this invention envisions that the cards can be of a double density type, wherein opposite sides can be made with suitable combinations of the noted embodiments. For example, these flip card arrangements may include cards wherein each side is made of the read only construction noted in the earlier embodiments. In this connection each opposing side would be joined together by an adhesive and each would be read in a reflection mode. Alternatively, each of the opposing sides could include any one of the writable and/or erasable constructions noted above. In such situations the latter the constructions would, preferably, be read in a reflection mode. The opposing constructions would be joined together by suitable adhesives.

Claims: An optical information storage card (10, 30) having a rectangular format, said card comprising: a substrate (32) having on at least one surface thereof an optically writable textured information surface (38) having a predetermined pattern which is strongly absorbent of at least a predetermined band of wavelengths of incident writing electromagnetic radiation and which may be written on through physical distortion of said predetermined pattern by such radiation, and at least one set of optically read only surface relief formations constituting read only information (34, 35) which facilitate optical machine reading of said substrate; and, a protection layer (40) being superposed over said optically read only surface formations (34, 35), said protection layer (40) covering gaps (36) over said textured surfaces (38), both said substrate (32) and said protection layer (40) being transmissive to electromagnetic radiation used for optically reading said relief formations (34, 35) and said writable surface (38), said substrate (32) forming said textured surface (38) and said relief formations (34, 35) being defined by a common sheet material having both said writable and read only information surfaces (38, 34, 35) embossed thereon. The card of claim 1, wherein said substrate (32) and said layer (40) are formed of materials which are pliant and durable. The card of claim 1 or 2, wherein said embossable material is selected from polycarbonate, cellulose acetate butyrate, polyester, polyethylene terephthalate, vinyl, acrylic, polystyrene, or thin metal. The card of any of the claims 1 to 3, wherein said embossed writable and/or read only surfaces (38, 34, 35) are arranged in a generally concentric and/or spiral format. The card of any of the claims 1 to 4, wherein said writable surfaces (38) are formed in depressions formed by said surface relief formations (35). An optical information storage card (10, 30) having a rectangular format capable of being carried in a wallet, said card comprising: a substrate (32) having on at least one surface thereof an optically writable textured surface (38) having a predetermined pattern which is strongly absorbent of at least a predetermined band of spectral wavelengths of incident writing electromagnetic radiation and which may be written on through physical distortion of said predetermined pattern by such radiation, and at least one set of optically read only surface relief formations constituting read only information (34, 35) which facilitate optical machine reading of the substrate; a first layer (37) in superposed relationship over said relief formations (34, 35), said first layer being made of material reflective to the predetermined band of wavelengths of the reading radiation; and, a protection layer (40) superposed over said first layer (37), said protection layer (40) covering gaps (36) over said textured surfaces (34, 35); at least one of said substrate (32) and said protection layer (40) being reflective to the electromagnetic energy used for optically reading said writable and read only information surfaces (38, 34, 35), said substrate (32) forming said textured surface (38) and said relief formations (34, 35) being defined by a common sheet material having both said writable and read only information surfaces (38, 34, 35) embossed therein. The card of claim 6, wherein said substrate (32) and said layers (37, 40) are formed of materials which are pliant and durable. The card of claim 6 or 7, wherein said embossable material is selected from polycarbonate, cellulose acetate butyrate, polyethylene terephthalate, vinyl, acrylic, polystyrene, or thin metal. The card of any of the claims 6 to 8, wherein said embossed writable surface (38) and/or said relief formations (34, 35) are arranged in a generally concentric and/or spiral format. The card of any of the claims 6 to 9, wherein said writable surfaces (38) are formed in depressions formed by said surface relief formations (35).

Inventors: KIME MILFORD B, SLAFER WARREN D, KIME, MILFORD B., SLAFER, WARREN D.
Applicants: POLAROID CORP, POLAROID CORPORATION
Application year: 1988
Main classification: G11B7
IPC codes: G06K19, G11B7