Method for making a wallet card with an integral magnifying lens

A wallet card adapted for use in reading externally stored information includes a transparent, substantially non-foldable semi-rigid base. The semi-rigid base includes a magnifying lens. The lens is formed by heating a lens forming die to a temperature sufficient to soften the base material and then cooling the die prior to withdrawing the die from the base material.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to pocket magnifiers and is specifically
 directed to a wallet card, such as a credit card, having an integral
 magnifying lens.
 2. Prior Art
 There have long been reading lenses and magnifying glasses available to
 assist people in reading books, documents and the like without the use of
 reading glasses. These are particularly useful when the person encounters
 small print during an activity which makes it inconvenient or difficult to
 stop and put on reading glasses.
 As an example, a book mark such as that shown in U.S. Pat. No. 3,140,883
 issued to R. L. Anthony on Jul. 14, 1964 may be integrally attached to a
 book such as a telephone directory or a dictionary, wherein the end of the
 book mark is provided with a sealed pocket for receiving a plastic
 magnifying lens. The magnifying lens may be moved up and down the page as
 desired to provide magnification of the text in the book. This permits the
 user to read the text without first putting on his eyeglasses.
 A pocket magnifier such as that shown in U.S. Pat. No. 3,409,347 issued to
 R. Vogel on Nov. 5, 1968 includes a pocket pouch adapted to be carried in
 the breast or hip pocket of the user or in a purse or wallet. The lens is
 formed of a transparent plastic sheet material having a substantial degree
 of stiffness and having fresnel lens contours molded into its upper
 surface. The lens unit may be slidably retracted into and extended out of
 the pocket. The pocket magnifier may be easily utilized to magnify small
 print and the like when the user Is in a location where it is not feasible
 or desirable to stop an activity in order to put on reading glasses.
 Other examples of special purposes magnifying lens structures are shown, by
 way of example, in U.S. Pat. No. 4,044,889 entitled "Cosmetic Container
 Including Integrated Lens Structure," issued to S. Orentreich et al. on
 Aug. 30, 1977, and U.S. Pat. No. 4,393,610 entitled "Card Caring Microfilm
 and Associated Reading Lens and Process of Forming Same," issued to D.
 Adrian on Jul. 19, 1983.
 With the ever expanding use of credit cards and other transaction cards,
 there is an increasing requirement that the card user be able to verify a
 transaction at the point-of-use. This means the user must be able to read
 the card invoice to determine the accuracy of the information before he
 signs the invoice to indicate his acceptance. Since most of the
 information on the invoice is impact printed either on a carbon set or
 carbonless form, the print is not only controlled in size but is often of
 a low contrast with respect to the base form paper. This makes the form
 difficult to read, particularly for those who normally require reading
 glasses. Also, when the transaction card is used, it is often not
 convenient to take the time to put on reading glasses before reviewing the
 card invoice. While the pocket magnifiers of the prior art could be used
 for this purpose, use of such devices requires a separate activity which
 does not provide a great improvement over the use of reading glasses. As a
 result, many credit card users simply do not take the time and effort to
 accurately verify a transaction at the point-of-sale, relying on the sales
 clerk for the accuracy of the information. A transaction card
 incorporating a magnifying lens has been proposed in Japanese Utility
 Model Application Kokai No. 2-56680 published Apr. 24, 1990. This
 reference, however does not disclose a method for efficiently
 manufacturing such a card.
 Therefore, there remains a need for a practical, cost-efficient method of
 manufacturing a financial transaction card with an integral magnifying
 lens.
 SUMMARY OF THE INVENTION
 It is, therefore, an object and feature of the subject invention to provide
 for a financial transaction card having an integral magnifying lens
 permitting the user to immediately verify financial transactions at the
 point-of-sale without first requiring that the user put on reading glasses
 or the like.
 It is another object and feature of the invention to enhance the use of
 credit cards by permitting immediate verification of credit card
 transactions by users normally having difficulty in reading small print,
 without requiring an additional activity of locating a magnifying lens or
 putting on reading glasses.
 It is another object and feature of the subject invention to provide for a
 credit card having an integral magnifying lens and adapted for enlarging
 the small print generally used in the confined space of the credit card
 transaction form.
 It is yet another object and feature of the invention to provide for an
 integral lens in a financial transaction card wherein the lens does not
 interfere with the machine readable information required on the card in
 order to complete a point-of-sale transaction.
 The subject invention is directed to a wallet card, such as a credit card
 or the like, which incorporates an integral magnifying lens. Use of the
 card of the subject invention automatically places a magnifying lens at
 the disposal of the user, whereby, for example, the user may immediately
 verify a financial transaction at the point-of-sale without first locating
 a magnifying glass or taking the time and effort to put on reading
 glasses. As an illustrative example, the invention is particularly useful
 when making credit card transactions during an activity where the user
 would not normally be wearing his reading glasses. For example, during
 sports activities or other types of activities where a person does not
 normally encounter reading material, it may be desirable to make a credit
 card transaction in order to pay for rental of equipment or user fees or
 the like. By using the credit card of the subject invention, the user can
 immediately read and verify the financial transaction at the point-of-sale
 by placing the magnifying lens incorporated in the credit card over the
 printed material on the transaction form. Thus, the print is magnified
 with the card used for the transaction, eliminating the need to locate a
 pocket magnifier or the time and effort required to put on reading glasses
 in order to verify the transaction.
 In a preferred form of the invention, a typical card blank is subdivided
 into a plurality of zones, specifically a data zone and a non-data zone.
 The data zone is adapted for receiving and carrying machine readable
 information as prescribed by ISO standards. Information may be carried on
 the card in the form of a strip such as a magnetic strip including
 magnetically encoded information, embossed alpha numeric lettering for
 creating an imprint on the credit card transaction form, a bar code or
 variants thereof, and for electronic data, smart card IC contact area or
 contactless smart card keep out area, or a combination of smart card
 contact areas and contactless smart card keep out areas for so-called
 combi-cards. The non-data zone is generally free of any information
 required to be machine read, although this zone often includes identifying
 indicia, logo types and other information relating to the issuing
 institution. In one preferred form of the invention, a portion of the
 non-data zone includes an integral magnifying lens carried in and forming
 a part of the card. It has been found that a substantially rigid,
 transparent plastic material of a thickness corresponding to the thickness
 of the card base may be incorporated in a window provided in the base. In
 a preferred embodiment of the invention, the transparent plastic includes
 fresnel lens contours on one of its surfaces for defining a magnifying
 lens. By placing the lens in the non-data zone, the lens does not
 interfere with the machine transactions required in order to use the card
 for its primary purpose.
 In a more specific embodiment of the invention, the lens is an elongated
 rectangle generally placed in parallel with the magnetic strip which is
 commonly attached to the back of the card. In this embodiment, there is no
 alteration of the data zone as commonly incorporated on cards.
 A second embodiment of the invention incorporates a lens with a larger
 usable area. However, this particular embodiment requires alteration of
 the data zone. Depending on the issuing institution, one embodiment may be
 more desirable over the other, depending on the flexibility of the
 location and format of the data zones on the card.
 In a typical wallet card, the base is made of a substantially semi-rigid
 plastic material which is printed on one or both sides and laminated with
 a thin material on both the top surface and the bottom surface thereof.
 The card may include identifying indicia, logotypes and the like on the
 top, a magnetic strip, a signature strip and various terms and conditions
 on the bottom. In one embodiment of the invention, the lens may be placed
 in the card prior to the laminating process, whereby the laminate cover
 materials may be used to overlap the edge of the lens and help retain it
 in the card. The lens may be sonically welded, adhesively secured or
 otherwise mounted in a window in the card base, with or without utilizing
 the laminate material of the card to assist in framing and mounting the
 lens in the card.
 In another embodiment, the lens is integral with the card base. In this
 embodiment, the card base is formed from a transparent material, such as
 an amorphous plastic. The stamped card base can be overprinted, laminated
 with printed material, etc. Thereafter, fresnel lens contours are stamped
 on a surface of the blank in a selected area to define the magnifying
 lens. A hologram may also be added after the lamination.
 In a particularly preferred embodiment, the inventive card comprises a
 substantially non-foldable yet still flexible semi-rigid base. The
 semi-rigid base comprises a magnifying lens. The card further comprises a
 strip, such as a magnetic tape strip, for carrying machine readable
 information, and optionally other features such as a signature strip or
 hologram patch.
 The semi-rigid base can be a laminate formed from a plurality of layers, or
 can be a single layer. The magnifying lens may be formed by stamping
 fresnel contours directly onto a surface of the semi-rigid laminate, or a
 surface of a single layer. The fresnel contours are stamped into a
 transparent area of the laminate or single layer, and together with the
 transparent area form the magnifying lens.
 There are also provided methods of producing a wallet card as described
 above. One such method comprises the steps of providing a transparent,
 substantially non-foldable semi-rigid base; forming a shallow cavity in
 the base; partially filling the cavity with a radiation or heat curable
 liquid resin; impressing a lens pattern on the surface of the resin with a
 die; and exposing the resin to radiation or heat of sufficient intensity
 to cure the resin.
 Another method of producing a wallet card in accordance with the present
 invention comprises the steps of making a card blank having a transparent
 window region; heating a lens-forming die to a first temperature
 sufficient to soften the card blank; impressing the lens-forming die into
 the window region of the card blank; cooling the lens-forming die to a
 second temperature at which the card blank is not significantly softened;
 and withdrawing the lens-forming die to leave a lens pattern on the
 surface of the card blank. This procedure can be realized by providing the
 heat to soften the card blank with a sonic source as well as more
 conventional heat sources to imprint the lens pattern.
 Other objects, features and advantages of the present invention will become
 apparent to those skilled in the art from the following detailed
 description. It is to be understood, however, that the detailed
 description and specific examples, while indicating preferred embodiments
 of the present invention, are given by way of illustration and not
 limitation. Many changes and modifications within the scope of the present
 invention may be made without departing from the spirit thereof, and the
 invention includes all such modifications.

DETAILED DESCRIPTION OF THE INVENTION
 In the following description, for purposes of explanation and not
 limitation, specific details are set forth in order to provide a thorough
 understanding of the present invention. However, it will be apparent to
 one skilled in the art that the present invention may be practiced in
 other embodiments that depart from these specific details. In other
 instances, detailed descriptions of well-known methods and devices are
 omitted so as to not obscure the description of the present invention with
 unnecessary detail.
 A typical credit card 10 is shown in FIG. 1. The size and general layout of
 card 10 have become standardized and similar cards are widely used for a
 variety of transactions and other purposes. Apart from credit cards,
 similar cards are used as debit cards, ATM access cards, driver's
 licenses, identification cards, library cards, etc. Such cards are
 typically carried in a wallet and are generally referred to herein as
 "wallet cards".
 Card 10 includes, as is common, embossed lettering at 12, which is machine
 readable for permitting the credit card to be imprinted at a point-of-sale
 transaction. As is shown in FIG. 2, most credit cards now contain a strip
 14 for carrying machine readable information, for example a magnetic strip
 material which includes magnetically encoded information readable by
 computer terminals utilized in many point-of-sale terminals. Also included
 is a signature strip 16 which is on the back of the card and which
 typically is adapted for receiving a signature to be manually applied by
 the user of the card. The card may further include one- or
 multi-dimensional bar codes as well as smart card contact, contactless or
 combi-card electronic information storage.
 The magnetic strip 14 and embossed lettering 12, along with the signature
 strip 16, identify a data zone on the card. For financial transaction
 cards, this data zone is generally controlled by ISO standards in an
 effort to standardize the cards so that various cards issued by a
 multiplicity of institutions may be used on standardized terminals the
 point-of-sale. For example, the placement of the magnetic strip 14
 relative to the top edge 18 of the card is standardized, as is the width
 of the strip 14 in order to permit ready readability of the magnetically
 coded information by any typical point-of-sale magnetic reader. Likewise,
 the font, size and position of the embossed lettering 12 is controlled to
 assure machine readability of the information imprinted from the card when
 a point-of-sale transaction is made on a typical credit card imprinter.
 Only the position of the signature strip 16 can be altered without
 interfering with the machine readability of the card.
 Today, many cards also include identifying indicia such as logotypes and
 the like as indicated at 20 for identifying the issuing institution. An
 increasing number of cards also include a hologram patch 22 which includes
 issuing institution indicia. The hologram panel 22 is generally located in
 or near the portion of the data zone including the embossed lettering 12.
 In the embodiment of the invention shown in FIGS. 1 and 2, a magnifying
 lens 24 is positioned in a window 25 provided in the base 11 of the card
 10 such that it is in noninterfering relationship with the magnetic strip
 14 and the embossed lettering 12. The magnifying lens 24 is an elongate,
 rectangular lens mounted parallel to the magnetic strip 14 in the space
 between the magnetic strip and the embossed lettering. This space is
 generally sufficient in size to accommodate the lens 24 since it is
 required that the embossed lettering 12 be spaced sufficiently from the
 magnetic strip 14 to assure that the embossing of the card does not in any
 way alter the functionality of the magnetic strip.
 In one embodiment of the invention, the lens member 24 comprises a
 substantially rigid, transparent plastic element having approximately the
 same rigidity as the credit card base. As shown in FIGS. 1 and 2, the
 credit card base 11 includes a window 25 having a top edge 30, a bottom
 edge 31 and side edges 32 and 33. The lens element 24 is adapted to be
 placed in the window 25 and has outer edges common with the window edges
 30-33. The lens may then be sonic welded or adhesively secured to the
 credit card base 11 in the manner well known to those who are skilled in
 the art. In the preferred embodiment of the invention, the lens 24 is of a
 thickness corresponding to the thickness of the credit card base 11,
 assuring that the presence of the lens in the credit card does not
 interfere in any manner with the machine readability of the information
 contained in the embossed lettering 12 or in the magnetic strip 14. A
 fresnel-type contour lens has been found to be particularly useful for
 this type of application. Such a lens is formed with concentric fresnel
 contour lines 36.
 An alternative embodiment of the invention is shown in FIGS. 3 and 4.
 There, the lens element 124 is of a substantially square cross section
 utilizing a fresnel lens comprising the concentric circle configuration
 shown at 60, and mounted in a complementary window 125 in the base 11.
 This particular configuration of the invention is useful when it is
 possible to alter the shape of the data zone and the placement of the
 embossed lettering 112. As terminal encoders come more widely accepted,
 and the magnetic encoding strip 14 (FIG. 4) more commonly used as the
 source for machine readable information, the importance of the embossed
 lettering is becoming diminished. This will permit alteration of the
 placement of the embossed lettering on the card without interfering with
 the machine readability of the card at the point of sale. This permits the
 embossed lens element 124 to be customized to varying desires and taste
 without interfering with the overall machine readability of the card.
 As is shown in FIG. 5, the typical card base 11 is a laminated composite
 member including a solid core material as shown at 48 with a thin plastic
 laminate 50 on the top surface and a similar thin plastic material 52
 laminated on the bottom surface. The term "thin" herein denotes that
 thicknesses of the plastic laminates 50 and 52 are small relative to the
 thickness of core 48. If desired, the core 48 and plastic laminates 50 and
 52 can have any relative thicknesses. The laminates 50 and 52 are
 generally printed in a four-color format, permitting attractive logotypes
 identifying the issuing institution and permitting customized color
 schemes for the card. The laminate materials 50 and 52 also carry the
 magnetic encoding strip 14, the signature strip 16 and the hologram panel
 22. As shown in FIG. 5, the fresnel lens element 124 is located in the
 window 125 of the card and may be secured therein by sonic welding,
 adhesives or the like along the side edges of the window, as at 60. Where
 a laminated card is used, the laminate material 50 and 52 may overlap the
 edges 62, 64 of the window and the lens 124 may include a peripheral lip
 or rim 58 for holding the lens in place. Of course, the lens may also be
 of a rectangular cross section and sonically welded or adhesively secured
 to the base 48 with or without use of the laminates 50 and 52.
 It will be understood that the lens could be incorporated in the card a
 variety of ways, including being an integral, unitary member of the card
 base. Integral, unitary lenses can be formed in a number of ways, such as
 by molding or casting a transparent material into a window of a semi-rigid
 base, or by stamping a transparent area of a semi-rigid base. FIG. 6
 illustrates one such alternative embodiment of the invention in which the
 lens is integral with the card base. Card base 48 comprises a
 substantially transparent plastic material. Preferably, the material is an
 amorphous plastic, such as polyvinyl chloride (PVC), polycarbonate,
 polyester or any other similar material. Lens 24 is formed in the card
 base 48 by, for example, stamping the desired fresnel contour lines 36
 onto a surface thereof. Embossed lettering (not shown) can be formed in
 the base simultaneously, or can be formed before or after the fresnel
 contour lines 36 are stamped onto the card base 48. Plastic laminates 50
 and 52 can optionally also be applied to the top and bottom surfaces of
 the card base 48. The order in which the foregoing stamping, embossing and
 laminating steps are carried out is a matter of routine design choice. In
 a preferred embodiment, described in greater detail below, the fresnel
 contours 36 are hot-stamped after a card blank has been laminated.
 As with the preceding embodiments, magnetic strips, signature strips,
 hologram patches, etc. can also be added in the conventional manner. For
 example, in FIG. 8, an embodiment of a card 10 includes a lens 24 which
 horizontally extends partially across card base 11. Card 10 also includes
 hologram patch 22. If desired, plastic laminates 50 and 52 can be omitted,
 and strips, patches, etc. can be applied directly to base 48.
 Another embodiment, shown in FIG. 9, includes a vertically-oriented lens 24
 stamped on one side of card base 11, with hologram patch 22 disposed near
 the opposite side of card base 11. Such an embodiment can, of course, also
 be produced by mounting a separate lens 24 in a card base 11 in a manner
 similar to the embodiment shown in FIG. 1.
 Still another embodiment is shown in FIG. 10. Card core 48 and bottom and
 top plastic laminates 50 and 52 comprise a substantially transparent
 plastic material, such as the amorphous plastics described above. Card
 core 48 can be comprised of a single layer, as shown, or can comprise
 multiple layers (a "split core"). Top and bottom plastic laminates 52 and
 50 are laminated to core 48, forming top and bottom layers around a core
 layer. The structure thus forms a semi-rigid and substantially
 non-foldable base. Lens 24 (not shown) is subsequently formed by stamping
 the desired fresnel contour lines 36 onto the surface of either top layer
 52 or bottom layer 50. Depending on the relative thicknesses of core 48
 and layers 50, 52, fresnel contours 36 may be impressed into core 48 as
 well as the layer 50 or 52.
 Preferably, core 48 and bottom and top plastic laminates 50 and 52 comprise
 the same substantially transparent plastic material. Bottom and top
 plastic laminates 50 and 52 preferably are colored over substantially all
 of their outer surfaces (areas 70 and 72), such as by printing, except for
 window areas 74 and 76. Core 48 can remain transparent, or can also be
 colored over substantially all of its lateral surfaces (areas 78 on either
 side of core 48), except for window area 80. The edges of core 48 can also
 optionally be colored. Window areas 74, 76 and 80 are located such that
 they are aligned when the laminate structure is formed. Together with
 fresnel contours 36, aligned window areas 74, 76 and 80 thus form
 magnifying lens 24.
 The transparent material forming core 48 and top and bottom plastic
 laminates 50 and 52 should be chosen to display refractive properties such
 that, together with appropriately designed fresnel contour lines 36, a
 magnifying lens 24 having the desired magnification is produced. Selection
 of suitable plastic materials, and design of appropriate fresnel contours,
 is a matter of routine design choice to those skilled in the art.
 Card 10 can include embossed lettering (not shown), as described
 previously, in addition to a magnetic strip and optionally a signature
 strip. A hologram patch can also be included. Other desired graphical
 features such as symbols, logos, pictorial representations, etc., can also
 be provided if desired. The magnetic strip, signature strip and/or
 hologram patch can be on either side of the card 10. That is, these
 features can be disposed on the same side of the card as the fresnel
 contours 36 are stamped on, or on the opposite side, in any desired
 combination. Placement of the various strips and patches in any embodiment
 of the instant invention is a matter of routine design choice.
 However, in the foregoing embodiment it is preferable that no lamination
 steps are carried out after fresnel contour lines 36 have been formed, or
 at the least no lamination steps over the entire surface of card 10
 including fresnel contour lines 36. This is because such subsequent
 lamination steps may fill in or flatten the fresnel contour lines 36 and
 thus render magnifying lens 24 inoperative.
 Fresnel contour lines 36 can be stamped into bottom 50 or top 52 plastic
 laminate in any desired orientation, such as horizontally, vertically,
 etc., and can be of any desired shape, such as rectangular, square,
 triangular, circular, oval, elliptical, star-shaped, diamond-shaped, etc.,
 similarly to the lenses 24 described previously.
 Selection of a particular embodiment from those described herein can be
 made by the individual manufacturer taking into account factors such as
 manufacturing capability, case of manufacture, cost, etc.
 Another embodiment is shown in FIG. 11. Here, card core 48 functions as a
 "top" layer, while bottom plastic laminate 50 comprises the "bottom"
 layer. Core 48 and bottom plastic laminate 50 again comprise a
 substantially transparent plastic material. Bottom plastic laminate 50 is
 laminated to core 48, forming top and bottom layers. The two layers
 together form a semi-rigid, substantially non-foldable laminate structure.
 Lens 24 (not shown) is subsequently formed in core 48 by stamping the
 desired fresnel contour lines 36 onto the top surface thereof.
 Alternatively, the lens contours may be stamped onto the bottom surface of
 laminate 50.
 As with the preceding embodiment, core 48 and bottom plastic laminate 50
 preferably comprise the same substantially transparent plastic material.
 Bottom plastic laminate 50 preferably is colored over substantially all of
 one or both of its sides (areas 70), such as by printing, except for
 window area 74. When both sides are so colored, core 48 can remain
 transparent, thus allowing printed information on the inner surface of
 bottom plastic laminate 50 (the side to which core 48 is laminated) to be
 read through the transparent plastic material. In the alternative, core 48
 can also be colored over substantially all of the surface opposite the
 surface to which it is laminated with bottom layer 50 (areas 78 on the
 outer side of core 48), except for window area 80. Window areas 74 and 80
 are located such that they are aligned when the laminate structure is
 formed. Together with fresnel contours 36, aligned window areas 74 and 80
 form magnifying lens 24.
 A variant of the foregoing preferred embodiment is shown in FIG. 12. Here,
 credit card core 48 functions as a "bottom" layer, while top plastic
 laminate 52 comprises the "top" layer. Core 48 and top plastic laminate 52
 again comprise a substantially transparent plastic material. Top plastic
 laminate 52 is laminated to core 48, forming top and bottom layers. The
 two layers together form a semi-rigid, substantially non-foldable laminate
 structure. Lens 24 (not shown) is subsequently formed in top layer 52 by
 stamping the desired fresnel contour lines 36 onto the top surface
 thereof. Alternatively, the lens contours may be stamped onto the bottom
 surface of core 48.
 Core 48 and top plastic laminate 52 preferably comprise the same
 substantially transparent plastic material. Top plastic laminate 52
 preferably is colored over substantially all of one or both of its sides
 (areas 72), such as by printing, except for window area 76. When both
 sides are so colored, core 48 can remain transparent, thus allowing
 printed information on the inner surface of top plastic laminate 52 (the
 side to which core 48 is laminated) to be read through the transparent
 plastic material. In the alternative, core 48 can also be colored over
 substantially all of the surface opposite the surface to which it is
 laminated with top layer 52 (areas 78 on the outer side of core 48),
 except for window area 80. Window areas 76 and 80 are located such that
 they are aligned when the laminate structure is formed. Together with
 fresnel contours 36, aligned window areas 76 and 80 form magnifying lens
 24.
 One process for making a card in accordance with the invention is
 illustrated in FIGS. 13-16. Referring first to FIG. 13, a card blank or
 core 202 is provided. The core material is transparent and is preferably
 polyvinyl chloride (PVC) although other suitable transparent materials may
 be used. A shallow cavity 204 is formed in the core material with a router
 206 or other suitable means. The dimensions of cavity 204 correspond to
 the desired dimensions of the lens 24 (FIGS. 1, 2, 6, 8 and 9) or lens 124
 (FIGS. 3, 4). As already explained, cavity 204 should be located in a
 non-data region of the card. The depth of cavity 204 will depend on the
 particular material used to make the lens as described below, but is
 generally on the order of 0.008 inches. It is important to minimize any
 residual tool marks which will leave the floor of cavity 204 with a frosty
 appearance and thereby impair the clarity and sharpness of images viewed
 through the lens. If necessary, the floor of cavity 204 may be polished to
 remove residual tool marks.
 Referring now to FIG. 14, cavity 204 is partially filled with a liquid
 resin. The preferred class of resins for use with the method described
 herein comprises radiation-curable resins, with the curing of the resin
 being carried out by exposure to a suitable source of actinic radiation,
 such as ultraviolet light. A particular resin suitable for such use is a
 proprietary product of Decochem having the designation 7294 mod 7025. This
 particular material has been found to produce excellent replication of the
 lens die profile, good adhesion to the PVC card core and poor adhesion to
 the surface of the die. Other suitable radiation-curable resin systems or
 thermosetting resin systems may also be used.
 Referring to FIG. 15, once cavity 204 has been filled with a sufficient
 quantity of liquid resin, a die 210 is brought into contact with the
 surface of the resin. Die 210 is machined with a negative image of a
 fresnel lens pattern. The die is brought into contact with the surface of
 the liquid resin, taking care to prevent entrapment of air and expulsion
 of resin from the cavity. Once die 210 is properly positioned, resin 208
 is exposed to the appropriate from of radiation or heat for a sufficient
 period of time to cure the resin. Using the preferred resin system, curing
 is accomplished in approximately 1-3 seconds.
 With reference to FIG. 16, the die 210 is removed after the resin has
 cured, leaving fresnel contours in the surface of the cured resin, thereby
 forming a lens 212. The lens contours are disposed below the upper surface
 of core 202, thereby helping to protect the lens from damage during
 routine handling.
 An alternative process for making a card in accordance with the present
 invention is illustrated in FIGS. 17-19. Referring first to FIG. 17, the
 structure of a card blank 302 prior to formation of the magnifying lens is
 shown in cross section. Card blank 302 comprises a laminated structure of
 several layers. Core material 304 is a transparent thermoplastic material.
 Suitable materials include PVC, polyethylene terephthalate modified with
 cyclohexanedimethanol (PETG) and polycarbonate, although other transparent
 plastic materials may also be used.
 The top and bottom surfaces of core material 304 are printed with a silk
 screen and/or gravure process to provide the card graphics as previously
 described. Depending on the process used and the nature of the inks
 employed, the thickness of printed layers 306 may range from less than 1
 to more than 5 mils. The printing applied to core 304 will generally be
 opaque, or at least translucent, over the entire card except for window
 region 308. This region must remain transparent for subsequent formation
 of the magnifying lens.
 After printed layers 306 have been applied, the top and bottom surfaces of
 core 304 are laminated with clear films 310. Films 310 are preferably PVC
 or other suitable clear plastic material. Films 310 are suitably bonded to
 core 304. Such bonding may require use of a transparent adhesive to adhere
 over printed layers 306.
 Films 310 typically have a thickness of about 1-3 mils. If printed layers
 306 are relatively thick, it may be desirable to apply a clear ink or a
 clear adhesive in window region 308 at the time of printing. Otherwise,
 films 310 may have a tendency to "drape" across the window region with the
 potential for voids to form between films 310 and core material 304 in the
 window region. Such voids would degrade the optical properties of a
 magnifying lens formed in the window region.
 Card blanks 302 may be conveniently manufactured in large sheets. Printing
 of core material 304 and lamination with films 310 is preferably done in
 large sheets. Individual card blanks 302 may then be die cut from the
 large sheets for further processing.
 Referring next to FIG. 18, a magnifying lens is formed on card blank 302
 with a hot stamping process using die 320. Prior to being impressed on
 card blank 302, die 320 is heated to a temperature which is sufficient to
 soften, but not necessarily melt, the plastic material of film 310 and
 core 304. Die 320 may be conveniently heated with a conventional heater
 cartridge, although sonic heating is an attractive alternative since it
 permits faster cycle times. Once the die has been brought up to
 temperature, it is impressed into card blank 302 to a depth sufficient to
 fully form the fresnel lens contours. An effective magnifying lens may be
 formed with contours having a depth of approximately 10 mils. In the case
 of sonic heating, heating and impressing may occur simultaneously.
 It is important to maintain the die precisely parallel to the surface of
 the card so that the lens contours are formed uniformly within window
 region 308. Such uniformity is necessary for the magnifying lens to have
 the desired optical properties and also prevents warping of the finished
 card. The lens contours are preferably formed on the bottom surface of
 card blank 302; however, an equally effective lens can be formed on the
 top surface.
 Die 320 preferably has a vent 322 so that air will not be trapped between
 the die and the surface of the card. Any such entrapment of air would
 interfere with proper formation of the lens contours and would degrade the
 optical properties of the lens. The need for vent 322 and its location, if
 needed, depend on the particular lens contour design.
 Once die 320 has been impressed to a desired depth in card blank 302, the
 die is cooled so that the plastic will set before the die is withdrawn.
 Cooling of die 320 is important for the quality and transparency of the
 magnifying lens. Cooling the die prevents plastic flow when the die is
 withdrawn, thereby insuring that the contours of the fresnel lens have
 sharp edges. This is important for achieving a high quality lens.
 Furthermore, it has been found that withdrawing the die prior to cooling
 tends to cloud the plastic. Any suitable means for cooling die 320 may be
 employed. In practice, it has been found that cooling may be effectively
 accomplished with compressed air blown directly onto the die.
 Alternatively, the die may be fabricated with internal channels for liquid
 or air cooling. Regardless of the means by which the die is cooled, it is
 desirable to minimize the thermal mass of the die so that the temperature
 of the die can be rapidly cycled.
 Using a hot stamping technique for forming the magnifying lens, it is
 important to confine the heat from the die as much as possible. Therefore,
 the platen 330 on which card blank 302 rests is preferably chilled. This
 helps to minimize distortions in the finished card.
 Once the fresnel lens contours have been formed, the optical quality of the
 lens may be conveniently tested using a simple photocell test arrangement.
 Assuming the focal length of a properly formed lens, a light source is
 positioned in a spaced-apart relationship relative to the photocell. Light
 from the light source is focused onto the photocell by the hot-stamped
 lens. The output of the photocell is proportional to the focusing
 properties of the lens and provides a gross quantitative measure of lens
 quality. More sophisticated automated or manual image quality tests can
 also be implemented as appropriate for fresnel lenses.
 The various embodiments of the invention described herein utilize a fresnel
 lens for magnification. Although this is the presently preferred type of
 lens for ease of manufacture, the invention is not limited in this regard.
 Suitable magnifying lenses may also comprise conventional convex lenses
 and other optical devices such as holograms. Whatever type of optical
 device is used for magnification, it may be mounted within the card or
 formed integrally with the card by any of the means previously described.
 The magnifying device may be formed in the core material, in a filler
 within a window in the core material and/or in a laminate applied over the
 core material.
 It will be recognized that the above described invention may be embodied in
 other specific forms without departing from the spirit or essential
 characteristics of the disclosure. Thus, it is understood that the
 invention is not to be limited by the foregoing illustrative details, but
 rather is to be defined by the appended claims.