JPS62108099A - Integrated circuit card - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] The process of prohibiting rewriting of an IC card can be easily performed by simply disconnecting the ground circuit.

[Industrial application field]

The present invention relates to an IC card, and particularly to an IC card that can easily perform rewriting prohibition processing.

In recent years, IC cards, which have a much larger storage capacity than magnetic cards, have become popular. However, as with magnetic cards, in many cases the recorded contents can be easily rewritten if a suitable device is available.

Depending on the use of the IC card, there are some cases in which it is necessary to prohibit rewriting of the recorded contents.

For example, there are certificates, notification documents, etc. In order to prohibit rewriting, a micro CPU, etc. is installed in the IC card, and the program's judgment function is used to prevent unauthorized rewriting, but the onboard circuit becomes complicated, so it is difficult to use a simple method that prohibits rewriting. Development is desired.

[Conventional technology]

A fuse-type ROM is known as one of the memories installed in conventional IC cards. This method uses a bit memory equipped with a fuse in a matrix circuit, and writes by blowing the fuse. Once written, the blown bit cannot be corrected.

Therefore, in order to record a small amount of data that cannot be rewritten using a fuse type ROM, it is inconvenient to store the data in another recording medium until the final data is completed.

Optically erasable EPR is used as a ROM to compensate for this drawback.
OM or electrically erasable EEFROM is known. These ROMs can be erased and rewritten with a suitable device.

An IC card that uses EEPROM as a storage element has a built-in micro CPU and is programmed to prevent unauthorized rewriting.

[Problems to be solved by the present invention]

The fuse type ROM has the inconvenience of requiring a separate recording medium, and has the drawback that there is a possibility that bits that are not partially blown out may be blown out.
EPROM can be erased and rewritten with a suitable device, but has the drawback that unauthorized rewriting cannot be prevented.

An IC card with a built-in micro CPU has the disadvantage of being expensive.

The present invention was created in view of the above-mentioned conventional drawbacks, and an object of the present invention is to provide an IC card equipped with a simple grounding circuit that can easily perform rewriting prohibition processing.

[Means for solving problems]

As shown in FIG. 1, the IC card of the present invention has a write control input circuit 2 (writable at ligh level,
In an IC card 1 equipped with a memory 3 having a write-inhibited state (defined as a write-protected state at level w), a fuse circuit 4 is provided in the write control input circuit 2, and mechanical disconnection is performed. The present invention is characterized in that a grounding circuit 5 is provided which disconnects the fuse circuit 4 and disables the output of the write control input circuit 2.

[Effect]

The IC is connected to the card cutting line 6 where the ground circuit 5 is indicated by a broken line.
When the corner of the card 1 is cut and removed, the input side of the inverter 7 of the write control input circuit 2 rises from the ground potential, and a logic value "1" is applied from the power supply terminal Vc.

As a result, the transistor 8 built in the inverter 7 becomes non-biased, so that an overcurrent flows from the power supply terminal Vc to the ground via the fuse circuit 4 and the transistor 8, and the fuse circuit 4 is blown.

As a result, the output side of the inverter 7 becomes a logical value "0" indicating that writing is prohibited, and becomes a write-inhibited state.

Therefore, rewriting is impossible.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

In order to make the description of the configuration and operation easier to understand, the same parts will be designated by the same reference numerals throughout the design and their repeated description will be omitted.

FIG. 1 shows a circuit diagram of this embodiment. In the figure, 1 is I
The memory 3 is a C card and has a write control input circuit 2. The memory 3 can be erased and rewritten until write prohibition processing is performed, such as [F, P
It consists of ROM etc.

4 is a fuse circuit that connects the output terminal of the write control input circuit 2 (
It is inserted between the control input terminal of the memory 3) and the power supply terminal Vc. Reference numeral 5 denotes a ground circuit, which is inserted between the input end of the write control input circuit 2 and the ground, and is constructed so that it can be cut at a cutting line 6 of the IC card 1 shown by a broken line.

Alternatively, the ground circuit 5 may be cut by punching a hole directly above it.

Reference numeral 7 denotes an inverter constituting the write control input circuit 2, and 8 a built-in transistor on the output side of the inverter, whose collector is connected to the output terminal and whose emitter is connected to ground.

In such a configuration, when the lower left corner of the IC card 2 is cut and removed from the card cutting line 6, the ground circuit 5 is cut off. When the IC card 1 is inserted into the device after the ground circuit 5 is disconnected, the input side of the inverter rises from the ground potential, and a logic value "1" is applied to the inverter 7 from the power supply terminal Vc. As a result, the transistor 8 built in the inverter 7 becomes non-biased, so that an overcurrent flows from the power supply terminal Vc to the ground via the fuse circuit 4 and the transistor 8. As a result, the fuse of fuse circuit 4 is blown before transistor 8 is destroyed.

As a result, the output side of the inverter 7 becomes a logical value "0" indicating that writing is disabled. Therefore, even if data is input, writing becomes impossible. That is, the rewriting prohibition process is executed by simply mechanically disconnecting the ground circuit 5.

In addition to cutting and removing the corners of the IC card 1 described above, the earth circuit 5 can be cut by punching a hole directly above the circuit.

FIG. 2 shows a circuit diagram of an applied embodiment of the present invention. In the figure, reference numeral 11 is an IC that is enclosed in a package and has, for example, dual in-line pins, and has a built-in ROM.
A modification of the C card is shown. ■2 indicates an IC socket, 13 indicates a printed board, etc. In this way, in the case of a package type, a function corresponding to the ground circuit 5 in FIG. Once connected, the write-protection process is accomplished by breaking off a particular pin 14 from the base of the pancage.

c. Effects of the Present Invention] As described above in detail, according to the IC card of the present invention, it is possible to easily execute the rewriting prohibition process, and to realize a low-cost, high-reliability IC card.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 shows a circuit diagram of an applied embodiment of the present invention.

Claims (1)

[Claims] An IC card (1) comprising a memory (3) having a write control input circuit (2), wherein the write control input circuit (2) includes a fuse circuit (4).
and a grounding circuit (5) that disconnects the fuse circuit (4) and disables the output of the write control input circuit (2) when mechanical disconnection occurs. IC card.