JPH01219981A - Ic card - Google Patents

Abstract

PURPOSE:To allow the title IC card to have generality, and also, to constitute it so that data of a large capacity can be stored by providing a compressing means of the data and a data expanding means for expanding the compressed data. CONSTITUTION:Data which is supplied to a signal connecting mechanism is inputted to a data compressing/expanding circuit 15 under the control of a CPU 12, subjected to a compression processing of the data therein, and thereafter, stored in a memory 13. The compressed data read out of the memory 13 is inputted to the data compressing/expanding circuit 15, and brought to expansion processing therein. Data whose read-out has been requested from the outside among the data which is returned to the original state by the data compressing/expanding circuit 15 is supplied to the signal connecting mechanism 14 through the CPU 12, and sent out to an IC card reader/writer device therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an IC card, and particularly to an IC card that is effective when writing a relatively large amount of data into a built-in memory.

[Conventional technology]

IC cards can store a larger amount of data than magnetic cards that record data on magnetic stripes. Data stored in an IC card is supplied from, for example, an IC card reader/writer device to an input/output terminal provided on a plastic card serving as the IC card body, and is stored in a memory as is. This stored data is read out and used as needed.

[Problem to be solved by the invention]

Although IC cards can store a relatively large amount of data as described above, they have their own limits.

Therefore, if one IC card is to be shared for various purposes, the memory capacity will be limited.

In order to improve this point, a memory card in which a plurality of memory elements are arranged on one plastic card has also been proposed. If a plurality of memory elements are arranged, the memory capacity will also be significantly increased. However, as the data storage capacity increases, address information for specifying target data within the memory also increases, making the circuit configuration of the IC card more complex.

On the other hand, it is also conceivable to compress the data input to the IC card from the beginning. With this method, you can save memory capacity by the amount of compression, and as a result, you can store more data. However, when this method is used, the compressed data cannot be used as is in the IC card. That is, I
In order to enable data processing within the C card, a circuit for decompressing the compressed data is required, but in this case, the compression method on the data supply side and the decompression method on the IC card side may be paired. It becomes necessary. As a result, such an IC card can only be used for a specific host device, resulting in a problem of lack of versatility.

SUMMARY OF THE INVENTION An object of the present invention is to provide an IC card that is versatile and can store a relatively large amount of data.

[Means to solve the problem]

In the present invention, (i) an external input/output terminal, (ii) a data compression means for compressing data manually entered into the external input/output terminal, and (iii) data compressed by the data compression means. The IC card is provided with a memory for storing the obtained compressed data, and (iv) data decompression means for decompressing the compressed data read from the memory.

That is, in the present invention, an IC card is provided with a data compression means and a data decompression means for decompressing the compressed data, so that any data can be compressed, and the compressed data can also be decompressed. This allows the decompressed data to be output externally or used internally.

〔Example〕

The present invention will be described in detail with reference to Examples below.

FIG. 1 shows an outline of the circuit configuration of an IC card in an embodiment of the present invention. 1 as the card body
A CPU (central processing unit) 12 and a memory 13 are arranged within the plastic card 11 . CPU
12 is connected to an IC card reader/writer device (not shown) by a signal connection mechanism 14 consisting of an external input/output terminal, and is configured to receive data supply and output data to the outside. The CPU 12 is connected to the memory 13 via a data compression/expansion circuit 15.

The operation when externally writing data into the memory of an IC card having such a configuration is as follows.

That is, the data supplied to the signal connection mechanism 14 is
The data is input to the data compression/expansion circuit 15 under the control of the PL 112, where it undergoes data compression processing. Existing techniques such as the modified Huffman method can be used for data compression.

The compressed data obtained in this way is stored in the memory 13.

Next, processing of data read from the memory 13 will be explained.

The compressed data read from the memory 13 is input to the data compression/expansion circuit 15, where it is expanded. Among the data restored by the data compression/expansion circuit 15, the data requested to be read from the outside is transferred to the CP
The signal is supplied to the signal connection mechanism 14 via U12, and sent from there to the above-mentioned IC card reader/writer device. The data to be internally processed is processed into a desired form under the control of the CPL 112, and the data to be stored is inputted again to the data compression/expansion circuit 15, compressed, and then stored in the memory 13. It turns out.

In the embodiments described above, all the data stored in the memory is compressed, but depending on the content of the data, the effect of compression may not be produced. Data that is not suitable for compression processing may be stored in the memory as is. Alternatively, the host device may instruct the CPU in the IC card as to whether or not compression is appropriate.

Furthermore, in the embodiment described above, the CPLI 12 and the memory 1
Although the data compression/expansion circuit 15 is arranged between the data compression/expansion circuit 15 and the data compression/expansion circuit 15, a separate memory for storage during decoding may be prepared and this may be directly connected to the CPU 12 without going through the data compression/expansion circuit 15. By separately preparing storage memory and temporary storage memory in this way, data processing speed can be improved.

〔Effect of the invention〕

According to the present invention, since data is compressed within the IC card, it is possible not only to substantially increase the data storage capacity, but also to change the compression method and compression ratio depending on the card used. , data can be stored efficiently depending on the purpose.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an IC card according to an embodiment of the present invention. l 1...IC card, 12...cpu. 13...Memory, 14...Signal connection mechanism, 15...Data compression/expansion circuit. Applicant NEC Corporation Representative Patent Attorney Umeo Yamauchi

Claims (1)

[Claims] An external input/output terminal, a data compression means for compressing data input to the external input/output terminal, and storage of compressed data obtained by compression by the data compression means. 1. An IC card comprising: a memory for decompressing data; and data decompressing means for decompressing compressed data read from the memory.