JPH06332760A - Information storage device - Google Patents

Abstract

PURPOSE:To provide a storage device in which the capacity of a storage medium can be substantially increased compared with a conventional case that simply unnecessary information is automatically erased after the lapse of a fixed time. CONSTITUTION:Each time the lapse of a prescribed time is clocked by a timer 3, a file 6 stored in a storage medium 1, in which the indication of the permission of automatic erasure is stored in a field F2 and the arrival of a time stored in a field F3 is clocked by the timer 3 is erased by a CPU 2. On the other hand, the file 6 in which the indication of the inhibition of the automatic erasure is stored in the field F2, and the lapse of the prescribed time since the latest time stored in a field F4 is clocked by the timer 3 is data-compressed by a data compressing circuit 4, and stored in a storage medium 1. Then, the original file 6 is erased from the storage medium 1 by the CPU 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can arbitrarily store information by various principles such as a magnetic storage device such as a hard disk device, a floppy disk device, a magnetic tape device, an optical disk device, or a RAM for electrically storing information. The present invention relates to an information storage device which uses a writable and readable storage medium and can automatically erase unnecessary information from the medium.

[0002]

2. Description of the Related Art Various storage devices are used in an electronic computer either internally or externally. In a storage device capable of arbitrarily writing and reading information in these storage devices, it is usually possible to write information in the same area in an overlapping manner. In that case, the previously written information is written. Is erased. However, if the amount of information written in the same storage device increases, the capacity of the storage medium used in the storage device will eventually be reached, and further information cannot be stored.

In order to avoid such an inconvenience, an invention as disclosed in, for example, Japanese Patent Laid-Open No. 63-143643 has been proposed. The invention disclosed in this Japanese Patent Laid-Open No. 63-143643 sets a storage time limit for information that only needs to be temporarily stored, and automatically deletes it after the time limit expires. It is intended to avoid wasting the capacity of the storage medium by unnecessarily storing unnecessary information for a long period of time and increase the substantial capacity of the storage medium. Incidentally, this Japanese Patent Laid-Open No. 63-143643
Various inventions similar to the invention disclosed in Japanese Patent Publication No. 61-267146 are known.

[0004]

As described above, the conventional storage device automatically erases information that is temporarily used only after a certain period of time, so that unnecessary information is not stored. Although it is possible to avoid the storage medium from being substantially reduced in capacity by being unnecessarily stored for a long period of time, it cannot be denied that it also has a limit.

The present invention has been made in view of the above circumstances, and is more effective than a conventional storage medium in which unnecessary information is simply erased after a certain period of time. An object of the present invention is to provide a storage device that can substantially increase the capacity.

[0006]

A storage device according to the present invention comprises a storage medium for storing a plurality of units of information, an erasing unit for selectively erasing each unit information stored in the storage medium, and a time. A timekeeping means for timing information and an information operation time memory for storing the time at which the unit information stored in the storage medium is written to or read from the storage medium according to the timekeeping result of the timekeeping means. Regarding the means and each unit information stored in the storage medium,
With respect to the erasure information storage unit that stores information as to whether or not automatic erasure is permitted, and the erasure permission time from the storage medium regarding each unit information in which the fact that the automatic erasure is permitted is stored in the erasure information storage unit Erasing permission time storage means for storing the data, compression means for compressing each unit information stored in the storage medium, and compressed data stored in the storage medium after being compressed by the compression means to the original information. Restoring means for restoring, and for each piece of unit information in which the erasure information storage means stores the fact that automatic erasure is permitted, timing means for indicating that the time stored in the erasure permission time storage means has been reached When the time is measured, the unit information is erased from the storage medium by the erasing means, and the erasure information storing means stores information indicating that automatic erasure is not permitted, when the information is operated. When the time measuring means measures that a predetermined time has elapsed from the latest time stored in the storing means, the unit information is compressed by the compressing means and stored in the storage medium, and the original information is deleted by the erasing means. An information storage device characterized in that it is designed to be erased from a storage medium.

[0007]

In the storage device of the present invention, automatic erasure is permitted in the erasure information storage means of each unit information stored in the storage medium each time the timekeeping means measures a predetermined time. The unit information, which has been stored by the timekeeping means when the time stored in the erasure permission time storage means is stored, is erased by the erasing means, while the automatic erasure is permitted in the erasing information storing means. Is stored, and the unit information obtained by the time measuring means measuring that a predetermined time has elapsed from the latest time stored in the information operating time storage means is compressed by the compression means and stored in the storage medium. At the same time, the original information is erased from the storage medium by the erasing means.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments thereof. FIG. 1 is a block diagram showing a configuration example of a storage device according to the present invention. Reference numeral 1 is a storage medium, and 2 is
A CPU, 3 is a timer, 4 is a data compression circuit, and 5 is a data decompression circuit. The storage device of the present invention can be an independent device having the configuration shown in FIG. 1 or can be configured to be incorporated in a computer system.

As the storage medium 1, specifically, a floppy disk device or a magnetic tape device is used. The storage medium 1 functions not only as a storage medium for information to be stored by the storage device of the present invention but also as an information operation time storage means, an erase information storage means, and an erase permission time storage means. The CPU 2 controls the entire storage device of the present invention shown in FIG. 1 and functions as a means for writing, reading, and further erasing information in the storage medium 1. Incidentally, the storage of the present invention is as described above. If the device is configured as part of a computer system, CPU 2 may use the CPU as the core of the computer system rather than the dedicated CPU.

The timer 3 functions as a time counting means, and keeps the time counting even when the power of the apparatus shown in FIG. 1 is shut off by being backed up by a battery. The data compression circuit 4 functions as a compression means, and compresses information according to a predetermined method to create compressed data. Further, the data decompression circuit 5 functions as a decompression unit, and decompresses the compressed data created by the data compression circuit 4 to the original information and decompresses it.
Since various methods have already been put to practical use for data compression and decompression, a detailed description thereof will be omitted.

FIG. 2 is a schematic diagram showing the structure of each piece of information stored in the storage medium 1, that is, a file. In FIG. 2, reference numeral 6 indicates individual files, and each of the files 6 is unit information stored in the storage medium 1. Each file 6 has label area LA and file area
It is composed of FA and. The file area FA is an area in which original information to be stored in the storage medium 1, for example, information such as a document and an image formed of a plurality of pages is stored.
The label area LA is provided to store various information regarding each file 6.

The label area LA is divided into a plurality of fields, reference numeral F1 is a field for storing a file number, and the number uniquely assigned to each file 6 is stored. F2 is a field for storing an erase permission bit and functions as an erase information storage means. Whether or not deletion of each file 6 is permitted is "1" or "0" in this field F2.
It is stored as data. F3 is a field for storing the erase permission time and functions as an erase permission time storage means. The time when each file 6 should be erased is stored in this field F3. Note that this field F3 is valid only when erasing is permitted in the above field F2. F4 is a field for storing the latest operation time and functions as an information operation time storage means. The field F4 stores the time when each file 6 was recently operated, that is, read or written. It should be noted that this field F4 is valid only when erasing is not permitted in the above field F2.

The operation of the information storage device of the present invention having such a configuration will be described with reference to the flowchart of FIG. 3 showing the processing procedure of the CPU 2. The timer 3 keeps the normal clock time, and the CPU 2 outputs information indicating the time as a result of the clocking.
Is given to. The CPU 2 is shown in FIG.
The process shown in the flow chart is started (step S1).

First, the CPU 2 sets the file number i = 1.
(Step S2), the file 6 (the file number 1 in this case) in which the number corresponding to the field F1 of the label area LA is stored is searched and the label area LA is read (step S3). Next, the CPU 2 determines whether or not the erasing of the file 6 is permitted based on the value of the erasing permission bit stored in the field F2 of the label area LA.
(Step S4). If the erasing of the file 6 is permitted, the CPU 2 determines whether or not the erasing permission time stored in the field F3 of the label area LA has already passed (step S5). The CPU 2 erases the entire file 6 from the storage medium 1 if the erase permission time has already passed (step S6), and does not erase the file 6 if it has not passed. After this, the process proceeds to step S7.

On the other hand, when the value of the erasure permission bit stored in the field F2 of the label area LA does not permit erasure in the processing of step S4, the CPU 2 stores it in the field F4 of the label area LA. It is determined whether or not the most recently operated time that has been performed is earlier than a predetermined time (step S9). If the latest operation time is more than the specified time, CP
The U 2 reads the file area FA of the file 6 from the storage medium 1, causes the data compression circuit 4 to compress the data, and stores the obtained compressed data in the storage medium 1 again as the file area FA of the file 6 (step S10). ). If the latest operation time is not earlier than the predetermined time, the data compression processing as described above is not performed. After this, the process proceeds to step S7.

In step S7, the CPU 2 causes the file number i
Determines whether the number n of files that can be stored in the storage medium 1 has been reached, and if the file number i has reached n, the process returns to step S1 described above, and a standby state is set until a predetermined time elapses. . If the file number i has not reached n, the CPU 2 increments the file number i by "1" (step S8) and returns the process to step S3.

As a result of the processing by the CPU 2 shown in the flowchart of FIG. 3 as described above, deletion of each file stored in the storage medium 1 is permitted each time a predetermined time elapses. Files for which the deletion permission time has already passed are deleted, while files for which deletion has not been permitted and for which the predetermined time has passed since the time of the most recent operation are data-compressed and re-stored in the storage medium 1. To be done.

When reading a file stored in the storage medium 1 in the form of compressed data, the CPU 2 restores the file to the original uncompressed ordinary file by the data decompression circuit 5. Output.

Further, in the above embodiment, the label area LA of each file 6 stored in the storage medium 1 is configured to function as the information operation time storage means, the erase information storage means, and the erase permission time storage means. However, it is of course possible to separately provide a storage means different from the storage medium 1 to perform the corresponding function.

[0020]

As described above in detail, according to the information storage device of the present invention, the information which only needs to be temporarily stored is automatically erased from the storage medium at a preset time. Also, since the information that needs to be permanently stored is compressed and re-stored in the storage medium if no read operation or write operation is performed for a predetermined time or more, the capacity of the storage medium is effective. Can be used for.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a storage device according to the present invention.

FIG. 2 is a schematic diagram showing a configuration of individual information, that is, a file, stored in a storage medium of a storage device according to the present invention.

FIG. 3 is a flowchart showing an operation procedure of the information storage device of the present invention.

[Explanation of symbols]

 1 storage medium 2 CPU 3 timer 4 data compression circuit 5 data decompression circuit 6 file F1 file number field F2 erase enable bit field F3 erase enable time field F4 last operation time field

Claims (1)

[Claims] 1. A storage medium for storing a plurality of units of information, an erasing unit for selectively erasing each unit information stored in the storage medium, a clocking unit for clocking time information, and the storage medium. With respect to each of the stored unit information, information operation time storage means for storing the time at which writing to or reading from the storage medium is performed according to the time measurement result of the time measurement means, and stored in the storage medium. Regarding each unit information that is stored, the erase information storage unit that stores information as to whether or not automatic erase is permitted, and the unit information that the erase information storage unit stores that automatic erase is permitted An erase-permitted time storage means for storing an erase-permitted time from the storage medium, a compression means for compressing each unit information stored in the storage medium, and the compression means. Each unit information in which the fact that the automatic erasure is permitted is stored in the erasure information storage means, and the decompression means for decompressing the compressed data stored in the storage medium into the original information. With regard to the above, when the time counting means measures that the time stored in the erasing permission time storing means has been reached, the unit information is erased from the storage medium by the erasing means, and the unit information is stored in the erasing information storing means. Regarding each unit information in which the fact that automatic erasure is not permitted is stored, when the time measuring unit measures that a predetermined time has elapsed from the latest time stored in the information operation time storage unit, the unit information concerned Is compressed by the compression means to be stored in the storage medium and the original information is erased from the storage medium by the erasing means. Information storage device that.