IC CARD

Abstract: An IC card capable of effectively preventing electrostatic breakdown of an IC even when it is charged with static electricity is provided. In the IC card, a discharging member (2 to 5) of a non-insulator is provided at a portion of IC card (1). Thus, even when IC card (1) is charged with static electricity, discharge current of static electricity is discharged through discharging member (2 to 5), so that the discharge current is effectively prevented form flowing into IC (101). As a result, even when IC card (1) is charged with static electricity, electrostatic breakdown of IC (101) is prevented, whereby breakdown or malfunction of entire IC card (1) is avoided.

Description: Technical Field The present invention relates to IC cards, and more specifically to an IC card including an integrated circuit (IC) for performing data transmission. Background Art JP 04336299 discloses a non-contact IC card with an IC chip mounted on a printed circuit board, where the periphery of the IC chip is encircled with a sealing frame having a conductor surface plated on parts of it. JP 04112096 discloses a reflection type IC card, where two shielding copper foils are bonded to the surface and the rear part of a card substrate within a region containing the arranging part of an IC chip. The two copper foils on opposite sides of the substrate are connected via a bent part on a portion of the edge of the card substrate. US 4,563,575 describes an identification card having an embedded IC module. Electrically conductive layers are applied to the front and back of the card in the area of the IC module. These layers may be connected via a conductive connection, for example a through hole close to the IC module. JP 06183189 describes an IC module, mounted on a board, where a conductor is covering the periphery of the board, which is connected to a conducting surface via a through hole inside of the module. Some IC cards perform data transmission with a terminal electrically connected to a control portion, while others perform data transmission in a non-contact state. In the non-contact type IC card, power is obtained form a radio wave from an antenna for transmission of information stored in the internal non-volatile memory. Such non-contact type IC card is used for a gate of the ski lift, gate at the station and sorting of parcels and the like. Fig. 6 is a schematic diagram showing a structure of a conventional non-contact type IC card. As shown in Fig. 6, a conventional non-contact type IC card 1 includes an IC 101 and an antenna 102 connected to IC 101. IC 101 and antenna 102 are contained in IC card 1. IC card 1 is generally formed of an insulating material such as polyester or vinyl chloride. The non-contact type IC card as shown in Fig. 6 is generally referred to as an RFID (Radio Frequency ID Card). The structure of the above described IC card 1 tends to be subjected to static electricity, which may in some cases cause a change in data stored in the non-volatile memory in IC 101. More specifically, IC card 1 is formed of the insulating material and has high resistance, whereas IC 101 and antenna 102 are both conductive and have lower resistance as compared with IC card 1. Thus, when static electricity or the like is externally transferred to IC card 1, discharge current of the static electricity may flow into IC 101 and antenna 102. If the discharge current of static electricity flows into IC 101 and antenna 102, electrostatic breakdown of IC 101 is caused. As a result, breakdown and malfunction of the entire portion of IC card 1 are disadvantageously caused. More specifically, as shown in Fig. 7, for example, assume that a portion A of IC card 1 is held by a person charged with static electricity when a portion B is grounded. In this case, discharge current of static electricity first flows into that portion of insulating material at the surface of IC card 1 which is positioned at A, and then into IC 101 and antenna 102 of IC card 1 for being discharged from portion B. This may lead to a problem associated with breakdown of the entire card including IC 101 and antenna 102. Such problem also arises, for example, when a ground rod is brought closer to the electrically charged card. The present invention is made to solve the aforementioned problem, and it is an object to provide an IC card capable of effectively preventing electrostatic breakdown of an IC even when the IC card is charged with static electricity. The object is attained by a non-contact IC card according to claim 1. Disclosure of Invention In an IC card such provision of the discharging member of the non-insulator enables discharge current of static electricity to be discharged through the discharging member, thereby effectively preventing the discharge current from flowing into the integrated circuit even when the IC card is charged with static electricity. Thus, electrostatic breakdown of the integrated circuit is prevented even when the IC card is charged with static electricity, so that breakdown or malfunction of the entire IC card is prevented. Brief Description of Drawings Fig. 1 is a schematic diagram showing a non-contact type IC card not according to the present invention. Fig. 2 is a schematic diagram showing a non-contact type IC card according to an embodiment of the present invention. Fig. 3 is a schematic diagram showing a non-contact type IC card not according to the present invention. Fig. 4 is a schematic diagram showing a non-contact type IC card not according to the present invention. Fig. 5 is a partial cross section showing the IC card according to Fig. 4. Fig. 6 is a schematic diagram showing a conventional non-contact type IC card. Fig. 7 is a schematic diagram shown in conjunction with a problem of the conventional non-contact type IC card. Fig. 1 is a schematic diagram showing a non-contact type IC card not according to the present invention. As shown in Fig. 1, an IC card 1 includes an IC 101 and an antenna 102 as in the conventional IC card. A discharging member 2 of a non-insulator is provided in a prescribed region of IC card 1 including an insulating material such as polyester or vinyl chloride. The non-insulator refers to metal such as copper, conductive rubber, conductive resin, conductive coating or the like. Discharging member 2 may be formed for example by providing a through hole as a through hole in the printed circuit board and forming metal such as copper on the inner surface of the through hole. When the through hole is not formed, it is desirable that the discharging member 2 has a thickness which is at least greater than those of antenna 102 and IC 101. More specifically, when the IC card has a thickness of 0.76 mm, antenna 102 has a thickness of 0.2 mm to 0.3 mm and IC 101 has a thickness of 0.3 mm, discharging member 2 preferably has a thickness of at least 0.3 mm. Thus, as the thickness of discharging member 2 is greater than those of antenna 102 and IC 101, the discharge current of static electricity readily flows into discharging member 2 when IC card 1 is charged with static electricity. Although discharging member 2 is provided only at one portion in Fig. 1, such discharging member 2 may be provided at several portions. If discharging members 2 are provided at several portions, the discharge current of static electricity more readily flows into discharging member 2, so that the discharge current is more effectively prevented from flowing into IC 101 and antenna 102. As described above in Fig. 1, as discharging member 2 of a non-insulator is provided in a region other than that where IC 101 and antenna 102 of IC card 1 including insulating material is provided, the discharge current of static electricity more readily flows into discharging member 2 when IC card 1 is charged with static electricity. As a result, the discharge current is effectively prevented from flowing into IC 101 and antenna 102. Accordingly, electrostatic breakdown of IC 101 is prevented even when IC card 1 is charged with static electricity, so that the problem associated with the breakdown or malfunction of the entire IC card 1 is avoided. Fig. 2 is a schematic diagram showing a non-contact type IC card according to an embodiment of the present invention. Referring to Fig. 2, in the second embodiment, a discharging member 3 of a non-insulator is provided at a periphery of IC card 1. Discharging member 3 may be for example in a coil like form. Such provision of discharging member 3 at the periphery of IC card 1 enables discharge current of static electricity to flow into discharging member 3 when IC card 1 is charged with static electricity, whereby the discharge current is effectively prevented from flowing into IC 101 and antenna 102. Thus, the problem associated with electrostatic breakdown of IC 101 when IC card 1 is charged with static electricity is avoided. Fig. 3 is a schematic diagram showing a non-contact type IC card not according to the present invention. Referring to Fig. 3, a mesh (net) like discharging member 4 of a non-insulator is arranged on front and back surfaces and ends of IC card 1 including an insulating material. Such mesh like discharging member 4 can readily be formed, for example, by providing a conductive pattern with printing. The provision of such mesh like discharging member 4 of the non-insulator also enables the discharge current of static electricity to flow into the mesh like discharging member 4 when IC card 1 is charged with static electricity, so that the discharge current is effectively prevented from flowing into IC 101 and antenna 102. Thus, when IC card 1 is charged with static electricity, electrostatic breakdown of IC 101 is prevented. As a result, the problem associated with malfunction or the like of the IC card is effectively avoided. Fig. 4 is a schematic diagram showing a non-contact type IC card not according to the present invention, and Fig. 5 is a partial cross section of the card shown in Fig. 4. Referring to Figs. 4 and 5, a discharging member 5 of a non-insulator is provided to surround IC 101 except for a terminal portion. In other words, discharging member 5 is provided to shield IC 101. The provision of discharging member 5 of the non-insulator to shield IC 101 also enables the discharge current of static electricity to flow into discharging member 5 when IC card 1 is charged with static electricity, so that discharge current 5 is effectively prevented from flowing into IC 101. Thus, electrostatic breakdown of IC 101 is effectively prevented when IC card 1 is charged with static electricity. As a result, malfunction or the like of IC card 1 is avoided. Referring to Fig. 5, it is noted that when the thickness of IC card 1 is 0.76 mm and the thickness of IC 101 is 0.3 mm, the thickness of discharging member 5 is preferably about 0.5 mm. Metal such as copper, conductive rubber, conductive resin or conductive coating may be used for the non-insulator of discharging member 5. It is noted that, the term "IC card" used in the present invention may include a card in a disk like shape, module like configuration or the like. As in the foregoing, according to the present invention, electrostatic breakdown of the IC is effectively prevented even when the IC card is charged with static electricity, so that breakdown or malfunction of the entire IC card can be avoided.

Claims: A non-contact IC card including an integrated circuit (101) and an antenna (102) connected thereto, said IC card further including a non-insulating discharging member (3) arranged at a portion of the IC card said discharging member (3) being formed from any of conductive rubber, conductive resin, conductive coating and metal, characterized in that said discharging member (3) is arranged along the whole periphery of said IC card.

Inventors: IKEFUJI YOSHIHIRO, UEDA TAKASHI, IKEFUJI, YOSHIHIRO, UEDA, TAKASHI, IKEFUJI, YOSHIHIRO ROHM CO., LTD., UEDA, Takashi Rohm Co., Ltd.
Applicants: ROHM CO LTD, ROHM CO., LTD.
Application year: 1997
Main classification: G06K19
IPC codes: G06K19, B42D15, G06K17