IC card

Abstract: An IC card has a card body with a frame 5a and a plurality of slits 5b extending through the frame in the thicknesswise direction, and a pair of metallic panels 20a, 20b secured to the card body. The metallic panels have engaging portions 21a, 21b which extend into the slits when the metallic panels are secured to the card body so that the engaging portions of both panels engage with each other within each slit e.g. by claws 50 and retainers 51, so as to fasten both metallic panels to the card body. The electrical potentials of both metallic panels are equalized through these engaging portions.

Description: BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to an IC card panel. DESCRIPTION OF THE RELATED ART Fig. 1 is a perspective view of a conventional IC card, while Fig. 2 is a sectional view taken along the line II-II of Fig. 1. Referring to these Figures, the conventional IC card 10 has a card body 1 with metallic upper panel 2a and a metallic lower panel 2b secured to the upper or obverse side and lower or reverse side of the card body 1. The card body 1 has an electric circuit board 4 supported in a mid position in the breadthwise direction of the frame 5 or the thicknesswise direction of the card, the circuit board 4 having semiconductor memory devices 3 as electronic components packaged on both major surfaces thereof. Referring specifically to Fig. 2, the circuit board 4 is supported by supporting steps (not shown) formed in the front and rear inner surfaces of the frame 5 and fixed thereto by means of, for example, an adhesive. The upper and lower panels 2a and 2b fit on the upper and lower sides of the frame 5 so as to protect the internal parts including the semiconductor memory devices 3. More specifically, recesses for fittingly receiving the panels are formed along the peripheral edges of the upper and lower sides of the frame 5, and the panels 2a, 2b are received in these recesses and fixed to the frame 5 by, for example, an adhesive. Thus, the panels are secured without protruding beyond the surfaces of the frame 5. A plurality of electrode terminals 6 for exchange of signals between the semiconductor memory devices 3 and external devices are provided on one end surface of the frame 5. The frame 5 further has a bore 5a which extends in the direction of breadth of the frame 5, A potential equalizer spring 7 is mounted in the bore 5a so as to contact with the upper panel 2a at its one end and also with the lower panel 2b at its other end. The construction of the panels of the known IC card will be described in more detail. Referring to Fig. 1, the upper panel 2a and the lower panel 2b are fixed to the frame 5 by suitable means such as double-sided adhesive sheets or an adhesive agent. In order that the internal devices such as the semiconductor memory devices 3 inside the card body 1 have improved durability against electrostatic charges, it is necessary to keep the panels 2a and 2b at the same electrical potential, i.e., to keep them electrically connected to each other. This can be accomplished by the potential equalizer spring 7 which is received in the bore 5a formed in the frame 5 as explained before. In the know IC card having the described construction, the upper and lower panels 2a and 2b are bonded only at small bonding areas, so that problems such as separation of the panels are often experienced due to insufficient bonding strength. In addition, the number of parts is increased and the assembly process is complicated due to the use of the potential equalizer spring 7 for keeping the electrical conduction between both panels 2a and 2b. EP-A-0 456 856, published on 16.05.90, disclose a card body with a pair of metallic panels covering the card body. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an IC card in which the strength of bonding of both panels to the frame is enhanced and the necessity for the potential equalizer spring for electrically connecting both panels is eliminated so as to reduce the number of parts and to facilitate the assembly, thereby overcoming the above-described problems of the prior art. To this end, according to one aspect of the present invention, there is provided an IC card comprising: a card body having a predetermined thickness and accommodating at least one electronic component therein; an input/output portion provided on said card body and enabling exchange of signals between said electronic component and an external device; a pair of metallic panels covering respective sides of said card body so as to protect said card body and said electronic component; the card body being provided with at least one passage extending in the direction of thickness of said card body; electrically conductive connecting means extending between the metallic panels, characterised in that the connecting means comprise at least one electrically conductive first engaging portion provided on one of said metallic panels and extending into the or a said passage when said metallic panels are secured to said card body, and at least one second engaging portion formed on the other of said metallic panels and extending into said passage so as to engage with said first engaging means within said passage such that said first and second engaging means retain one another and thereby retain the metallic panels. Thus, in the IC card of the present invention, two panels are securely fixed to the frame as a result of engagement between a first engaging portion provided on one of the panels and a second engaging portion provided on the other panel, thus remarkably suppressing any tendency for these panels to come off the frame. By forming the first and second engaging portions from conductive materials, it is possible to maintain both panels in an electrically connected state and, hence, at the same electrical potential. These and other objects, features and advantages of the present invention will become clear from the following description of the preferred embodiment when the same is read in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig.1 is a perspective view of a conventional IC card; Fig. 2 is a sectional view taken along the line II-II of Fig. 1; Fig. 3 is a perspective view of an upper panel used in an embodiment of the IC card of the present invention; Fig. 4 is a perspective view of a lower panel used in the embodiment; Fig. 5 is a perspective view of the embodiment of the IC card incorporating the panels shown in Figs. 3 and 4; Figs. 6A and 6B are a front elevational view and a plan view of the IC card shown in Fig. 5 in a state before the engaging portions of both panels are brought into engagement with each other; Figs.7A and 7B are a front elevational view and a plan view of the IC card shown in Fig. 5 in a state in which the engaging portions of both panels have been brought into engagement with each other; Fig. 8 is a perspective view of a modification of the engaging portions provided on both panels in the IC card of the invention; and Fig. 9 is a perspective view of another modification of the engaging portions provided on the panels in the IC card of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described with reference to the drawings. Referring to Fig. 3 which is a perspective view of an upper panel used in the IC card embodying the present invention, the upper panel 20a made of a metal is provided with a pair of first engaging portions 21a formed on each longitudinal edge thereof. Each engaging portion includes a tab 30 projecting from the main part of the panel 20a and claws 50 which orthogonally project from both sides of the end of the tab 30 and extend obliquely inwardly of the IC card. These claws exhibit resiliency as they are bent slightly inwardly as explained above. In order to ensure sufficiently high mechanical strength of the engaging portions 21a, it is possible to provide the panel 20a with reinforcement portions 40 along both longitudinal edges of the panel 20a. Fig. 4 is a perspective view of a lower panel used in the IC card embodying the present invention. The lower panel 20b is provided with a pair of second engaging portions 21b formed on each longitudinal edge thereof. Each second engaging portion 21b has a tab 30 projecting from the main part of the lower panel 20b and retainers projecting orthogonally from both sides of the end of the tab 30. The lower panel 20b also can have reinforcement portions 40 to strengthen the second engaging portions as in the case of the upper panel shown in Fig. 3. The first engaging portions 21a and the reinforcement portions 40 of the upper panel 20a may be formed integrally with the main part of the upper panel by bending from a single sheet. Similarly, the second engaging portions 21b and the reinforcement portions 40 of the lower panel 20a may be formed integrally with the main part of the lower panel by bending from a single sheet. The first engaging portions 21a and the seocnd engaging portions 21b are made of an electrically conductive material or materials. Fig. 5 is a sectional view of the embodiment of the IC card of the invention incorporating the upper panel 20a and the lower panel 20b shown in Figs. 3 and 4. Unlike the conventional IC card, the illustrated embodiment of the IC card of the present invention has slits 5b which receive the first engaging portions 21a of the upper panel 20a and the second engaging portions 21b of the lower panel 20b so as to enable these engaging portions 21a and 21b engage with each other within each slit. The slits 5b are formed in the portions of the frame 5 corresponding to the first and second engaging portions 21a, 21b and the reinforcement portions 40 of both panels 20a and 20b. A description will be given of a process for assembly of the IC card with the upper and lower panels having the described constructions. As the first step, the lower panel 20b is fixed to the frame 5a by means of, for example, an adhesive (not shown). In this state, the second engaging portions 21b and the reinforcement portions 40 if provided are received in the slits 5b formed in the frame 5a. Subsequently, the upper panel 20a is fitted to the frame 5a such that the first engaging portions 21a are aligned with the slits 5b. The upper panel 20a maybe fixed to the frame 5a in this state. Figs. 6A and 6B show the IC card in the state before the first engaging portions 21a on the upper panel 20a and the second engaging portions 21b of the lower panel 20b are brought into engagement, in front elevation and in plan, respectively. Subsequently, the claws 50 of the first engaging portions 21a on the upper panel 20a and the retainers 51 on the second engaging portions 21b of the lower panel 20b are made to engage with each other, whereby corresponding first and second engaging portions 21a and 21b resiliently engage with each other, as shown in Figs. 7A and 7B. In the illustrated embodiment, each claw 50 on the upper panel 20a are tapered so that the claws 50 and the retainers 51 can securely engage with each other regardless of any dimensional fluctuation in the engaging portions 21a and 21b, since such fluctuation can be absorbed by a change in the position where the tapered claws 50 engage with the associated retainers 51, whereby the engagement between corresponding engaging portions can be attained with a higher degree of freedom. The taper for enhancing the degree of freedom, however, may be provided on the retainers 51 on the lower panel 20b instead of the claws 50 on the upper panel 20a. In such a case, the direction of the taper is reverse to that illustrated in Figs. 6A to 7A. The provision of the taper, however, is not essential and may be omitted. It will be also clear that there is no significant distinction between the upper and lower panels 20a and 20b. Namely, the arrangement may be such that the first engaging portions with claws are provided on the lower panel 20b, while the second engaging portions with the retainers are provided on the upper panel 20a. It is also possible to provide the resilient claws both on the upper and lower panels. In the illustrated embodiment, the engagement between the first and second engaging portions is attained by the anchoring effect produced between the claws and the retainers which anchor each other at their contacting edges. This, however, is only illustrative and the engaging portions can have any desired form provided that they can securely hold each other. For instance, as shown in Fig. 8, (a) and (b), the first and second engaging portions maybe formed by a resilient U-shaped hook portion 22a provided on one of the panels and a tab portion 22b formed on the other panel and having a slit 52 which can retain the U-shaped hook portion 22a. As shown in Fig.9, (a) and (b), it is also possible to arrange such that the engaging portions of both panels are formed of U-shaped resilient hook portions 23a, 23a which retain each other. As has been described, in the IC card of the present invention, both panels are securely held on the frame by virtue of the mutual engagement between the engaging portions provided on both panels, whereby the tendency for the panels to come off the frame is greatly suppressed. In addition, electrical connection between both panels is accomplished through the engaging portions on both panels, thus eliminating any necessity for a specific part for equalizing the potentials of both panels, whereby the number of parts is reduced and the assembly is facilitated greatly.

Claims: An IC card comprising: a card body (5) having a predetermined thickness and accommodating at least one electronic component (3) therein; an input/output portion (6) provided on said card body and enabling exchange of signals between said electronic component and an external device; a pair of metallic panels (20a, 20b) covering respective sides of said card body so as to protect said card body and said electronic component; the card body being provided with at least one passage (5b) extending in the direction of thickness of said card body; electrically conductive connecting means (21a, 21b) extending between the metallic panels, the connecting means comprising at least one electrically conductive first engaging portion (21a) provided on one of said metallic panels (20a) and extending into the or a said passage (5b) when said metallic panels are secured to said card body, and at least one second engaging portion (21b) formed on the other of said metallic panels (20b) and extending into said passage so as to engage with said first engaging means within said passage such that said first and second engaging means retain one another and thereby retain the metallic panels. An IC card according to Claim 1, wherein said card body includes an electric circuit board having major surfaces on both sides thereof, at least one electronic component mounted on at least one of said major surfaces of said circuit board, and a frame having a thickness different from the thickness of said circuit board, said frame surrounding the peripheral side surfaces of said circuit board and supporting said circuit board such that said circuit board is placed at a thicknesswise mid portion of said card body, wherein said pair of metallic panels are secured to both sides of said frame so as to cover and protect said major surfaces of said circuit board, wherein said at least one passage includes at least one slit formed in each of the portions of said frame on both sides of said circuit board and extending through said frame, and wherein said connecting means includes said first engaging portion formed on said one of said metallic panels at a position corresponding to each of said slits formed in said frame and said second engaging portion formed on the other of said metallic panels at a position corresponding to each of said slits formed in said frame. An IC card according to Claim 2, wherein said first engaging portion includes a tab projecting from an edge of said one of said metallic panels towards said card body into said slit and at least one claw formed on the end of said tab, while said second engaging portion includes a tab projecting from an edge of said the other of said metallic panels towards said card body into said slit and at least one retainer formed on the end of said tab and capable of retaining said claw of said first engaging means. An IC card according to Claim 3, wherein said second engaging portion includes a tab projecting from an edge of said the other of said metallic panels towards said card body into said slit and a pair of retainers extending substantially orthogonally from the end of said tab along said frame within said slit, and said first engaging portion includes a tab projecting from an edge of said one of said metallic panels towards said card body into said slit and extending on the outer side of said tab of said second engaging portion within said slit and further includes a pair of resilient claws projecting substantially orthogonally from both sides of the end of said tab and extending obliquely inwardly of said frame, said claws being retained by said retainers. An IC card according to Claim 4, wherein either one of said claws of said first engaging portion and said retainers of said second engaging portion being tapered such that said claws or said retainers converge towards their end extremities so as to absorb any dimensional fluctuation of said first and second engaging portions. An IC card according to Claim 2, wherein said second engaging portion includes a tab projecting from an edge of said the other of said metallic panels towards said card body into said slit and a pair of resilient claws substantially orthogonally projecting from the end of said tab and extending within said slit obliquely outwardly of said frame, and said first engaging portion includes a tab projecting from an edge of said one of said metallic panels towards said card body into said slit and extending on the outer side of said tab of said second engaging portion within said slit and further includes a pair of resilient claws projecting substantially orthogonally from both sides of the end of said tab and extending obliquely inwardly of said frame, said claws of said first and second engaging portions being retained by each other. An IC card according to Claim 6, wherein either one of said claws of said first engaging portion and said claws of said second engaging portion being tapered such that said claws or said retainers converge towards their end extremities so as to absorb any dimensional fluctuation of said first and second engaging portions. An IC card according to Claim 2, wherein said first engaging portion includes a resilient U-shaped hook portion extending into said slit, and said second engaging portion includes a tab extending into said slit and having a slit for retaining said U-shaped hook portion within said slit. An IC card according to Claim 2, wherein said first engaging portion includes a resilient U-shaped hook portion extending into said slit and bent within said slit inwardly of said frame in a U-like form, and said second engaging portion includes a U-shaped hook portion extending into said slit on the outer side of said U-shaped hook portion of said first engaging means and bend within said slit outwardly of said frame in a U-like form so as to engage with said U-shaped hook portion of said first engaging means. An IC card according to any of Claims 2 to 9, further comprising bnding means bonding at least one of said metallic panels to said frame. An IC card according to any preceding Claim, wherein said first and second engaging portions provide a conductive path for equalizing the electrical potentials of said metallic panels. An IC card according to any preceding Claim, wherein said first and second engaging portions are formed integrally with said first and second metallic panels, respectively. An IC card according to any preceding Claim, further comprising reinforcement portions on said metallic panels, said reinforcement portions projecting from the same edges of said metallic panels as said first and second engaging portions, respectively.

Inventors: ONODA SHIGEO C O KITAITAMI SEI, ONODA, SHIGEO, C/O KITAITAMI SEISAKUSHO
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1990
Main classification: H05K9
IPC codes: G06K19