Chip card reader

[0001] The present invention relates to a chip card reader, in particular to a chip card reader comprising a housing according to a PCMCIA format, the housing including a base plate and a cover plate extending between a plug-in socket and an insertion slot for a chip card.

[0002] Chip card readers of this kind are known from the prior art, for example from EP 0 735 507 A3. They are used as interfaces between a host device like a computer or a set-top-box and a chip card. Chip card readers are used in a large variety of applications and, accordingly, there is a high demand for low-priced but reliable chip card readers in the electronic market. Common chip card reader designs feature housings which are made of sheet metal, mainly for the sake of sufficient mechanical stability and temperature resistance.

[0003] It is the object of the invention to provide a chip card reader comprising a housing which is inexpensive and light in weight and yet satisfies high requirements in mechanical strength.

[0004] The chip card reader according to the invention comprises a housing according to a PCMCIA format. The housing includes a base plate and a cover plate extending between a plug-in socket and an insertion slot for a chip card. The base plate and the cover plate are each made of a plastic part and a metallic part and are assembled by interconnecting the metallic parts of both plates. It has been found that a housing of a chip card reader which is mainly composed of plastic parts and only particular components being made of metal can meet the high demands on mechanical strength. By interconnecting the metallic parts of the base and the cover plates sufficient stability of the housing is ensured. Due to the plastic parts the housing according to the invention is not as susceptible to plastic deformation as conventional metal housings. Moreover, the housing according to the invention has also shown to satisfy the common requirements in temperature resistance.

[0005] The base plate and/or the cover plate are preferably produced by a molding process in which the metallic part is inserted into a casting mold and molded around with plastic.

[0006] In a preferred embodiment of the invention the metallic parts of the base and cover plates are exposed along lateral edges of both plates. The metallic part of at least one of the base and cover plates has at least one bent side strip, the structure of the chip card reader enabling an assembly technique according to which the side strip is directly welded to the opposing exposed lateral edge of the other plate.

[0007] According to a particular aspect of the invention a printed circuit board with a chip card contacting unit and an intermediate plate are arranged between the base plate and the cover plate. The intermediate plate protects the printed circuit board from unintended damage upon insertion of a chip card.

[0008] To ease the insertion of a chip card having embossed (elevated) areas one of the cover and base plates has an internal card guiding structure comprising a pair of parallel guide bars. The guide bars extend along opposite longitudinal edges of the plate and have exposed guiding surfaces defining a common plane. The insertion slot has a narrow portion and a widened portion, the widened portion being defined by a stepped interior surface area of the plate. One of the guide bars has an end with a ramp face extending between the stepped surface area and the exposed guiding surface, allowing a continuous smooth gliding of the chip card into the accomodation channel of the chip card reader.

[0009] According to another aspect of the invention the housing of the chip card reader is provided with a physical coding matching with a corresponding physical coding of a printed circuit board. Thus, inadvertent installation of a wrong printed circuit board can be avoided.

[0010] Further details of the invention become apparent from the following description of the invention and from the enclosed drawings. In the drawings:

[0011] FIG. 1 is an exploded view of a chip card reader;

[0012] FIG. 2 is a perspective view of the interior side of a cover plate of a chip card reader;

[0013] FIGS. 3a, 3b are sectional detail views of welded base and cover plate portions near the plug-in socket and near the chip card receiving portion, respectively;

[0014] FIG. 4 is a perspective detail view of a part of a cover plate and a chip card;

[0015] FIG. 5a is a plan view of part of a vertically open chip card reader with a coding for a printed circuit board; and

[0016] FIGS. 5b-5e are details of the chip card reader of FIG. 4a with different codings.

[0017] The chip card reader 10 illustrated in FIG. 1 is composed of a base plate 12 and a cover plate 14; a printed circuit board 16 and an intermediate plate 18 are arranged between the base plate 12 and the cover plate 14.

[0018] The base plate 12 is configured of a main plastic part 20 and a metallic part, preferably a sheet metal part. The base plate 12 is preferably produced by a molding process in which a suitable metallic part is inserted into a particular casting mold and molded around with plastic. After the molding process only lateral portions 22 of the metal part extending along the longitudinal edges of the base plate 12 and an end piece 24 are exposed. The remaining portions of the metal part are surrounded by the main plastic part 20 of the base plate 12.

[0019] The cover plate 14 is generally produced and configured similar to the base plate 12. However, as can be seen in FIG. 2, an interior portion of the cover plate 14 adjacent the end piece 24 is not covered with plastic. Thus, the interior surface of the cover plate 14 has a plastic portion and a metallic portion 26. In this particular case the metallic portion 26 extends over the entire width of the cover plate 14. The corresponding exterior surface of portion 26 may be blank metal or plastic covered. The end of the main plastic part 20 opposite of the end piece 24 is formed as a chip card receiving portion 28. The chip card receiving portion 28 of the cover plate 14 may differ from the corresponding portion of the base plate 12 (as will be explained below).

[0020] The metallic part of the base plate 12 has bent up side strips 30 protruding from both lateral portions 22. The side strips 30 are located next to the chip card receiving portion 28 and next to the end piece 24. The metallic part of the cover plate 14 may have corresponding side strips 30 so that the base plate 12 and the cover plate 14 can be interconnected in a conventional manner by welding to each other the bent side strips 30 of both plates 12, 14. However, in the embodiment shown in FIG. 1 only the metallic part of the base plate 12 has side strips 30 while the cover plate 14 lacks such strips. To interconnect the base plate 12 and the cover plate 14 the side strips 30 of the metallic part of base plate 12 are directly welded to the metallic lateral portions 22 of the cover plate.

[0021] In FIGS. 3a and 3b connection points between a base plate 12 and a cover plate 14 are schematically illustrated in detail. According to the embodiment shown in FIG. 3a both the base plate 12 and the cover plate 14 have side strips 30 near the end piece 24 (not shown in FIG. 3a) which are welded to each other. In this context it has to be noted that the width of a standard chip card is 54 mm. Considering that in the region adjacent the end piece 24 a chip card reader must not exceed an overall width of 54 mm to fit into a standard PCMCIA slot of a host device, there would be no room for any side strips next to the chip card. However, since even a completely inserted chip card does not reach into this region of the chip card reader 10 according to the invention, the interior width can be less than 54 mm, allowing the provision of side strips 30 on both the base and the cover plate 12, 14, respectively, as shown in FIG. 3a.

[0022] In the region near the chip card receiving portion 28 the overall width of the chip card reader 10 may be slightly larger than the width of a 54 mm standard smart card on the one hand, but on the other hand, unlike in the region adjacent the end piece 24, an inserted chip card is present in this region. Therefore, the effective room for providing any side strips is less than in the region near the end piece 24. In order to still achieve a satisfactory connection between the base plate 12 and the cover plate 14 and to provide a lateral guidance means for the chip card, according to FIG. 3b only the base plate 12 is provided with side strips 30 near the chip card receiving portion 28 which are directly welded to an opposing edge of the metallic lateral portion 22 of the cover plate 14.

[0023] Returning to the illustration of FIG. 1, the printed circuit board 16 is equipped with a plug-in socket 32 attached to one of its longitudinal ends and providing electrical connection between the chip card reader 10 and a host device into which the chip card reader 10 is inserted. A grounding clip 34 facing the interior surface of the cover plate 14 is provided on the printed circuit board 16. The grounding clip 34 contacts the metallic portion 26 of the interior surface of the cover plate 14. The size and shape of the contacted metallic portion 26 of the cover plate 14, especially the dimension in the chip card insertion direction, may be adjusted to solve ECM problems. The printed circuit board 16 further holds a chip card contacting unit 36 with contacting elements facing downwards (according to the illustration of FIG. 1) to contact the contact field of a chip card (not shown in FIG. 1).

[0024] An intermediate plate 18 of similar size and shape like the printed circuit board 16 is provided between the base plate 12 and the printed circuit board 16. The intermediate plate 18 is preferably made of plastic and covers the conductor track side of the printed circuit board 16 facing towards the base plate 12. However, the intermediate plate 18 has a cut-out portion 40 corresponding to the contacting unit 36 of the printed circuit board 16 in position and shape. The intermediate plate 18 may have further cut-out portions or recesses corresponding to embossed (elevated) areas of particular types of chip cards.

[0025] In the assembled state the printed circuit board 16 and the intermediate plate 18 are mounted between the base plate 12 and the cover plate 14. Both end pieces 24 of the base and cover plates 12, 14 cover the plug-in-socket 32 attached to the printed circuit board 16. An accomodation channel for a chip card is formed between the base plate 12 and the intermediate plate 18 which protects the downfard facing conductor track side of the printed circuit board 16. The chip card receiving portion 28 opposite the end piece 24 of the cover plate 14 together with the corresponding part of the base plate 12 forms an insertion slot for a chip card.

[0026] When a chip card is inserted into the accomodation channel of the chip card reader 10 possible damage to the printed circuit board 16 due to tilting of the chip card 38 is prevented by the protective intermediate plate 18. The chip card 38 is supported by two parallel guide bars 42, 44 extending along opposite longitudinal edges of the cover plate 14 (see FIG. 3). After complete insertion of the chip card 38 the downward facing contact elements of the contacting unit 36, which protrude through the cut-out portion 40 of the intermediate plate 18, are in contact with the upward facing contact field of the chip card 38.

[0027] FIG. 4 shows an example of a cover plate 14 to be used in a chip card reader according to the invention. The parallel guide bars 42, 44 provided on the cover plate 14 extend from the chip card receiving portion 28 to the area next to the end piece 24. The guide bars 42, 44 have exposed guiding surfaces 46, 48 defining a common plane. The chip card receiving portion 28 of the cover plate 14 has a stepped surface area. One of the guide bars 44 has an end with a ramp face 50 extending between the stepped surface area and the exposed guiding surface 48. The stepped surface area of the chip card receiving portion 28 of the cover plate 14 together with the flat surface area of the corresponding portion of the base plate 12 define an insertion slot having a narrow portion and a widened portion.

[0028] The internal card guiding structure described above is particularly useful when chip cards with embossed areas are inserted into the chip card reader 10. According to the illustration of FIG. 2 such chip card is inserted into the insertion slot with the embossed areas on the right half of the chip card facing downwards. Since both the narrow and the widened portion of the insertion slot have to be wider than the thickness of the flat and of the embossed areas of the chip card, respectively, it cannot be excluded that upon insertion the chip card is tilted clockwise out of the common plane defined by the exposed guiding surfaces 46, 48 of the guide bars 42, 44. To avoid a possible jamming of the chip card in the insertion slot, the ramp face 50 provided at the end of guide bar 44 ensures that upon further insertion into the accomodation channel the chip card 38 is lifted upwards onto the guiding surface 48 of guide bar 44 as can be seen in FIG. 4.

[0029] It has to be understood that referring to the plates 12 and 14 of the housing as base plate and cover plate, respectively, is not limiting to the orientation of the chip card reader 10. Base plate 12 and cover plate 14 can also be interchanged. Moreover, the chip card receiving portion 28 with the stepped surface area can alternatively be formed on the base plate 12.

[0030] FIG. 5a depicts a chip card reader 10 with a printed circuit board 16 to be inserted into the housing. The housing is provided with a projection 52 positioned at a particular predetermined location. In the embodiment shown in FIG. 4a the projection 52 is formed behind the chip card receiving portion 28 facing the printed circuit board 16. The printed circuit board 16 has a corresponding recess 54 matching with the projection 52 of the housing. Accordingly, other printed circuit boards having smaller or elsewhere located recesses or no recesses at all cannot be installed into this particular type of housing. By this coding system misinstallation of printed circuit boards can be avoided.

[0031] FIGS. 5b to 5e show different codings, i.e. the individual projections 52 of the housings vary in position and size. Only printed circuit boards having the matching recesses 54 can be installed. For example, the printed circuit board 16 shown in FIG. 4a cannot be installed into any of the housings shown in FIGS. 4b to 4e.

[0032] Such coding system may be used with regard to the operating voltage of the chip card reader 10. For example, one particular matching projection/recess pair can be associated to an operation voltage of 5 Volt, which is the standard voltage according to a current PCMCIA standard, and another particular pair can be associated to an operation voltage of 3.3 Volt according to a future standard. In this case the above described coding system would prevent malfunction of or damage to components on an erraneously installed printed circuit board 16 due to a discrepancy between the supplied voltage and the proper operation voltage of the printed circuit board 16.

[0033] It has to be understood that any suitable physical coding system may be used for this purpose, especially the projection 52 of the housing and the recess 54 of the printed circuit board 16 may be interchanged, i.e. the projection 52 can be provided on the printed circuit board 16 while the recess 54 is provided in the housing.