JP3225754B2 - Data storage device and data reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data storage device for storing a plurality of data and a data reading device.

[0002]

2. Description of the Related Art In recent years, with the emergence of so-called multimedia equipment, it has been frequently performed to store a large amount of data such as image data and audio data in a data storage device having a large-capacity storage medium such as an optical disk. It is becoming more and more.

Conventionally, when such a large amount of data is stored in a storage medium, the individual data is coded in such a manner that the original data can be completely restored, such as run-length coding or entropy coding. Use data compression technology by lossless coding, or use JPEG (Joint Ph
otographic coding Experts Group) to shorten the data length using irreversible coding data compression technology that aims to shorten the data length by intentionally missing information that is difficult to recognize due to the characteristics of the five senses of the human. By doing so, the storage medium is effectively used.

As a technology that takes this one step further, it is noted that which one of a plurality of compression algorithms makes the data length after compression the shortest depends on the contents of individual data. Instead of applying a single compression algorithm to data, a technique has been proposed in which a plurality of compression algorithms are tried for each data, and the one with the shortest data length is selected and stored (for example, And JP-A-2-22869.

[0005]

However, a data storage device is required not only to effectively use a storage medium but also to be able to read data at high speed. In particular, when data is compressed and stored, this read time must be considered including the time required for data expansion.

[0006] However, the requirement to shorten the data length after compression and the requirement to decompress data at high speed are not always compatible, but rather are often contradictory.

For example, MH (Modified Huffman) compression and MR used for facsimile of International Standard Group 3
(Modified Relative addressing) Taking the compression as an example and comparing them for a large number of data, MH compression, which has a simple algorithm, can perform both compression and decompression of data at a relatively high speed. Although the data length is not so short, MR compression, which has a relatively complicated algorithm, takes longer time to compress and decompress data than MH compression, but the data length of generated data is shorter. Tend to be.

[0008] As described above, the request to shorten the data length after compression and the request to decompress data at high speed tend to be contradictory. If emphasis is placed solely on shortening the length, the time required for data decompression increases, and a problem occurs in that the data reading speed including this time decreases.

This problem is particularly serious in an environment where it is required to continuously read a plurality of data at regular time intervals.

[0010] For example, an image filing apparatus which stores image data and continuously displays the stored image at a predetermined time interval in a page-turning mode and retrieves the image (for example, Japanese Patent Application Laid-Open No. 57-1)
No. 08961), the data reading speed including the decompression time is significantly reduced for some data, and the time interval between displaying one image and displaying the next image is not sufficient. When it becomes stable, it becomes difficult for the user to watch the display screen with confidence. Conventionally, as a technique for keeping the image display time interval constant even if such a situation occurs, if a large amount of time is spent for data expansion and the like and the entire image of one page cannot be displayed within a predetermined time, A technique has been proposed in which the display of that image is interrupted halfway and the display of the next image is started (for example, see Japanese Patent Application Laid-Open No. 4-37957). However, in this technology, in exchange for keeping the image display time interval constant,
For individual images, we disclaim any guarantee that the entire image will be displayed, so for example, if the characteristic illustration or chart that is the key for the user to search for the image is near the bottom of the page, for example, If there is a part to be displayed later, there is a possibility that the part ends without being displayed, so that a new problem occurs that it becomes difficult to search for a desired image.

A similar problem also occurs when storing and reproducing audio data such as music and voice. The sound data is read at a predetermined sampling period, compressed and stored, and at the time of reproduction, they are sequentially read and decompressed.
Let's imagine an acoustic memory playback device that sounds a speaker or the like.
In this case, the data reading speed including the decompression time is allowed to decrease, and the time required for reading and decompressing the data is longer than the sampling period used for storing the acoustic data. Then, it becomes impossible to correctly reproduce the stored acoustic data with a speaker.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and guarantees that data decompression is completed within a predetermined allowable time, and at the same time, compresses data with a compression algorithm that shortens the data length. It is an object of the present invention to provide a data storage device and a data reading device that can store data.

[0013]

Means for Solving the Problems In order to achieve the above object, the present invention has the following constitution.

That is, the data storage device includes compression means for compressing data by a plurality of different compression algorithms,
Decompression means for decompressing data compressed by each compression algorithm, decompression time measurement means for measuring the time required for decompression of the compressed data, data length counting means for counting the data length of the compressed data, decompression A data selecting unit that selects one of the compressed data based on a measurement result of the time measuring unit and a counting result of the data length counting unit; and a data storage unit that stores the data selected by the data selecting unit. The configuration was adopted.

The data selection means has a comparison means for comparing the time measured by the decompression time measurement means with an upper limit value allowable as the decompression time. The comparison result of the comparison means and the count result of the data length counting means are provided. Data is selected based on the data.

Further, the data selecting means selects data having the shortest data length counted by the data length counting means from among data whose time measured by the decompression time measuring means is smaller than an upper limit value allowable as the decompression time. The configuration was adopted.

Further, the data selecting means is configured so that the decompressing means decompresses only the compressed data whose data length is shorter than the data before compression.

Further, the data selection means is configured to select data which is first detected that the time measured by the expansion time measuring means is smaller than an allowable upper limit value of the expansion time.

Further, the data selection means is configured to expand the compressed data to the expansion means in ascending order of data length.

When the time measured by the extension time measuring means exceeds an allowable upper limit value for the extension time,
The data is decompressed by the decompression means.

Further, the data selecting means selects the data which is not compressed when any of the compressed data has a time measured by the decompression time measuring means which is larger than an allowable upper limit of the decompression time.

Further, the data selecting means determines that any of the compressed data has a data length counted by the data length counting means which is larger than the data length of the data before compression.
The configuration is such that data that is not compressed is selected.

Further, the apparatus has an image input means for optically reading an image and photoelectrically converting the image data to compress image data generated by the compression means.

[0024] Further, the apparatus has a sound input means for compressing a sound signal generated by converting a sound into an electric signal by a compression means.

Further, the data reading device individually confirms that each of the plurality of different compression algorithms can be decompressed within a predetermined time for each data and decompresses the data compressed by the selected algorithm. Data storage means stored with an identifier indicating the data, read means for reading the compressed data and the corresponding identifier from the data storage means, expansion means for expanding the data read by the read means according to the read identifier And a conversion means for converting the data expanded by the expansion means into information recognizable by human senses at predetermined time intervals.

Further, the data stored in the data storage means includes image data, and the conversion means has a display means for displaying an image.

The display means is configured to display an image as a moving image. The data stored in the data storage means includes sound data, and the conversion means has a sound generation means for generating sound.

[0028]

The following effects are obtained by the above configuration.

That is, the data storage device compresses the data by a plurality of different compression algorithms by the compression means, decompresses the data compressed by each compression algorithm by the decompression means, and reduces the time required for decompression of the compressed data. The data length of the compressed data measured by the decompression time measuring means and the data length of the compressed data is counted by the data length counting means. Since the determination is made based not only on the counting result of the counting means but also on the measurement result of the decompression time measuring means, the data compressed by the compression algorithm with the shortest data length is not stored in the storage means, but is stored in the storage means. The data is selected in consideration of both the time required for decompressing the data and the data is stored in the data storage means. It becomes possible.

The comparing means compares the time measured by the decompression time measuring means with an upper limit allowable as the decompression time, and the data selecting means outputs data based on the comparison result and the count result of the data length counting means. Is selected, it can be guaranteed that the data stored in the data storage means can be expanded within the allowable time.

The data selecting means selects the data having the shortest data length counted by the data length counting means from among the data whose time measured by the decompression time measuring means is smaller than the upper limit value allowable as the decompression time. So
Among the compression algorithms that can expand within the allowable time,
The data compressed by the algorithm having the shortest data length is stored in the data storage means, and the storage medium can be used effectively.

Further, the data selection means causes the decompression means to decompress only the compressed data whose data length is shorter than the data before compression, so that all the compressed data is decompressed. It is possible to determine which algorithm is used to store compressed data in the data storage means faster than in the case of performing

Further, the data selecting means selects the data in which the time measured by the decompression time measuring means is first detected to be smaller than the allowable upper limit value of the decompression time. It is possible to determine at a higher speed whether to store the data in the storage means.

Further, the data selection means expands the compressed data to the expansion means in ascending order of the data length, so that the time measured by the expansion time measuring means must be smaller than the upper limit value allowable as the expansion time. It is possible to guarantee that the data detected first has the shortest data length after compression.

When the time measured by the extension time measuring means exceeds an allowable upper limit value for the extension time,
Since the decompression of the data by the decompression means is completed and the decompression of the new compressed data is started, it is faster than starting the decompression of the previous data and starting the decompression of the new compressed data. It is possible to determine whether to store the data compressed by the algorithm in the data storage means.

When the time measured by the decompression time measuring means is larger than the allowable upper limit of the decompression time, the data selecting means stores the uncompressed data which does not require decompression. Since the data is selected as the data to be stored in the storage device, it is possible to guarantee that the expansion is completed within the allowable time for any data.

Further, the data selecting means, when any of the compressed data has a data length counted by the data length counting means larger than the data length of the data before compression,
Since data not to be compressed is selected, it is possible to prevent the data length from being increased by compression.

Further, since the image is optically read by the image input means and the image data generated by photoelectric conversion is compressed by the compression means, the optically read image can be stored in the data storage means.

Further, since the sound signal obtained by converting the sound into the electric signal by the sound input means is compressed by the compression means, the sound can be stored in the data storage device.

Further, the data reading device individually confirms that the data can be expanded within a predetermined time among a plurality of different compression algorithms, and the data compressed by the selected algorithm and the method of expanding the data. Is read from the data storage means by the reading means, the read data is expanded by the expansion means in accordance with the identifier, and the expanded data is converted into information recognizable by the five senses of human beings. It can be presented to humans.

Further, the data stored in the data storage means includes image data, and the display means in the conversion means displays the image, so that the data stored in the data storage means is converted into a continuous image by human beings. It can be presented.

Further, it is possible to display a continuous image as a moving image by the display means.

Further, the data stored in the data storage means includes sound data, and the sound generation means generates sound, so that continuous information can be presented to a human as sound.

[0044]

An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram showing the configuration of a first embodiment of the data storage device of the present invention.

In FIG. 1, reference numeral 10 denotes a temporary storage unit realized by a hard disk. Reference numeral 11 denotes a compression / expansion means constituted by using a data compression / expansion IC (integrated circuit) for facsimile communication, in which a first compression means 11a, a second compression means 11b, and a first expansion means 11 are provided.
c and a second expanding means 11d. Reference numeral 12 denotes a data length counting unit, and reference numeral 13 denotes an extension time measuring unit realized by a crystal oscillator and a frequency divider. 14 is a CPU
(Central processing unit), data selection means realized by memory and software. Numeral 15 is a data storage means incorporating a large-capacity optical disk as a storage medium. Reference numeral 19 denotes an image input unit, which has a scanner 19a with an auto feeder 19b inside. These units are connected by signal lines 510 to 519.

The operation of each means in FIG. 1 will be described below. The operation of the data storage device is started by setting the paper on which the image is drawn on the auto feeder 19b of the scanner 19a provided in the image input means 19, and thereafter, the data storage operation is automatically performed. .

The image input means 19 includes an auto feeder 19
When the paper is set on the paper b, an image for one screen drawn on the paper is optically read by the scanner 19a, photoelectrically converted, and converted into signal data 510 as binary image data of white pixels and black pixels. Output to

The temporary storage means 10 reads the image data supplied via the signal line 510, and
Stored as c.

First compression means 11 in compression / expansion means 11
a is the uncompressed data 10 stored in the temporary storage 10
c is read via the signal line 511, compressed by the MH compression algorithm, and the result of the compression is written into the temporary storage means 10 via the signal line 512 as the first compressed data 10a.

After that, the second compression means 11b transmits the uncompressed data 10c stored in the temporary storage means 10 to the signal line 5
11 and compressed by the MR compression algorithm, and the result of the compression is written as the second compressed data 10b in the temporary storage means 10 via the signal line 512.

The data length counting means 12 includes a first compressed data 10a, a second compressed data 10b,
c, the signal line 51 from the temporary storage means 10
3 and calculates the number of bytes of the data length, and calculates the calculation result as the data length of the first compressed data 10a, the data length of the second compressed data 10b, and the data length of the uncompressed data 10c. Are output to the signal line 514 in this order.

Thereafter, the first decompression means 11c in the compression / decompression means 11 reads the first compressed data 10a stored in the temporary storage means 10 via the signal line 511, and subjects the read data to MH decompression. Decompress using algorithm. The data generated as a result of the decompression is not necessary here, and is discarded. In addition, a first decompression start signal is output to a signal line 515 when decompression of the first compressed data 10a is started, and a first decompression end signal is output to a signal line 515 when decompression is completed.

The second decompression means 11 d
0 is stored in the signal line 51.
1 and the read data is expanded using an MR expansion algorithm. Data generated as a result of the decompression is not necessary here, and is discarded. In addition, a second decompression start signal is output to the signal line 515 when decompression of the second compressed data 10b is started, and a second decompression end signal is output to the signal line 515 when decompression is completed.

The extension time measuring means 13 measures the time elapsed from the supply of the first extension start signal via the signal line 515 to the supply of the first extension end signal in milliseconds (thousandths). The measurement is performed in seconds, and the measurement result is output to the signal line 516 as a first extension time. For example, if the time elapsed from when the first decompression start signal is supplied to when the first decompression end signal is supplied is 170 milliseconds,
The value output to the signal line 516 is 170. Similarly, the time elapsed from the supply of the second decompression start signal via the signal line 515 to the supply of the second decompression end signal is measured in milliseconds, and the measurement result is stored in the second Is output to the signal line 516 as the extension time of

The data selection means 14 holds a predetermined calculation formula as an evaluation function. This evaluation function is, for example, the product of the decompression time value measured in milliseconds and the data length for each of the compressed data 10a and 10b, and 100 times the data length of the uncompressed data 10c. Set as double. This evaluation function can be freely set and changed by the user by connecting a keyboard to the data selection means 14 as appropriate.

The data selecting means 14 calculates the data length of the first compressed data 10a, the data length of the second compressed data 10b and the uncompressed data 10c supplied via the signal line 514.
Of the first compressed data 10a, the second compressed data 10b, and the uncompressed data 10c using the data length of the first compressed data 10a, the second compressed data 10b, and the uncompressed data 10c, using the first decompression time and the second decompression time supplied via the signal line 516. Then, the value of the evaluation function is calculated, and the calculated values of the three evaluation functions are compared to select the one with the smallest value. If the selected value is calculated for the first compressed data 10a, the temporary storage unit 1
The first compressed data 10a stored in 0 is read via the signal line 517 and output as it is to the signal line 518, and the value 1 is output to the signal line 519 as an identifier indicating the first decompression means 11c. On the other hand, when the selected value is calculated for the second compressed data 10b, the second compressed data 10b stored in the temporary storage unit 10 is read via the signal line 517. And outputs the value 2 to the signal line 519 as an identifier indicating the second decompression means 11d. If the selected value is calculated for the uncompressed data 10c, the uncompressed data 10c stored in the temporary storage 10 is read via the signal line 517 and output to the signal line 518 as it is. Then, the value 3 is output to the signal line 519 as an identifier indicating that there is no need to decompress the data.

The data storage means 15 stores the data supplied via the signal line 518 and the identifier supplied via the signal line 519 in association with each other.

After that, the temporary storage means 10 deletes the first compressed data 10a, the second compressed data 10b, and the non-compressed data 10c.

Here, attention has been paid to one image data, and the process from the reading of the image data by the image input means 19 to the storage of the image data in the data storage means 15 has been sequentially described. A plurality of images are sequentially read by the image input means 19 and the data storage means 15
Can be stored.

According to this embodiment, the algorithm for compressing the data supplied via the signal line 510 and storing the compressed data in the data storage means 15 is determined based on only the data length after compression. The data can be determined by considering both the data length after compression and the time required for decompressing the compressed data, so the data is compressed using an algorithm that requires an enormous amount of time to decompress the data to shorten the data length The danger of doing so can be eliminated in advance.

Since the user can arbitrarily set the evaluation function of the data selection means 14, for example, when the storage capacity of the data storage means 15 has a margin and high-speed data reading and decompression are required, The compression algorithm is determined with an emphasis on shortening the time required for decompression. If the storage capacity of the data storage unit 15 is not so large and reading and decompression of data do not require much speed, the compression Whether to decide on a compression algorithm with a focus on the time required for decompression, such as deciding on a compression algorithm with a focus on shortening the data length, or decide on a compression algorithm with a focus on shortening the data length after compression Can be appropriately selected by the user.

The data storage device may be incorporated as a part of a so-called image filing device, or may be realized as an independent device configured so that the storage medium of the data storage means 15 can be detached, and read out data. May be separately provided with a read-only device, and the device may read data from the storage medium.

(Embodiment 2) FIG. 2 shows a combination of a data storage device and a data reading device according to the present invention.
FIG. 2 is a block diagram illustrating a configuration of an embodiment of the image filing apparatus.

In FIG. 2, reference numeral 22 denotes a data selection means realized by a CPU (Central Processing Unit), a memory, and software. Reference numeral 22a denotes a data length memory provided in a memory included in the data selection means 22. Also,
22b is a counter provided in the data selection means 22. Reference numeral 22c denotes a comparison unit included in the data selection unit 22. Reference numeral 22d denotes a register included in the comparison data selection means 22. 23 is a reading instruction means,
24 is a timer, 25 is data reading means, 26 and 27 are image memories, and 28 is display means. Reference numeral 29 denotes an image input means, inside which a scanner 29a and a display means 29b are provided.
And an image processing means 29c comprising an image processor for a general-purpose computer. Reference numeral 30 denotes a keyboard. Reference numeral 31 denotes a compression / expansion means constituted by using a data compression / expansion IC for facsimile communication, in which a first compression means 11a, a second compression means 11b, a first expansion means 11c, and a second It has extension means 11d. 520 to 530 are signal lines. In addition, the same components as those in FIG. 1 are denoted by the same reference numerals as those in FIG.

Further, (Table 1) A to D show examples of values stored in the data length memory 22a. In Table 1, A1,
A2 and A3 are addresses, the address A1 contains the data length of the first compressed data 10a, and the address A2 contains the second data length.
The data length of the compressed data 10b is stored at the address A3, and the data length of the uncompressed data 10c is stored at the address A3.

[0067]

[Table 1]

Further, (Table 2) A to D represent the first decompression means 11 c and the second decompression time measured by the decompression time measurement means 13.
5 shows an example of the data expansion time of the expansion means 11d.

[0069]

[Table 2]

Table 3 shows examples of values stored in the register 22d.

[0071]

[Table 3]

Further, (Table 4) A to D represent comparison means 22c.
5 shows an example of the comparison result output by the following.

[0073]

[Table 4]

Hereinafter, the operation of the image filing apparatus shown in FIG. 2 will be described separately when storing image data and when reading image data.

First, the operation when storing image data will be described. The operation of storing image data is as follows. The user sets paper on which an image is drawn in the scanner 29a,
Is started by instructing to read an image by operating.

Keyboard 30 outputs a character code string representing a user's instruction to signal line 530.

The image input means 29 determines the character code string supplied through the signal line 530, and when instructed to read the image, optically reads the image drawn on the paper by the scanner 29a, After the conversion, the image data is displayed on the display unit 29b as image data including binary values of white pixels and black pixels. The display unit 29b may be realized by a CRT (cathode ray tube) or may be realized by using another display element such as a liquid crystal or a plasma display.

When the user looks at the image displayed on the display means 29b and wants to perform processing on the image, such as cutting out or rotating the image, before storing the image,
An instruction for performing the processing is input from the keyboard 30.

Based on this instruction, the image input means 29 processes the image specified by using the image processing means 29c, and displays the processed image on the display means 29b again.

The user repeats the same operation until a satisfactory image is obtained, and processes the image.

After a satisfactory image is obtained, when the user instructs storage of the image using the keyboard 30, the image data storage operation is performed as follows.

First, the image input means 29 is
The image data displayed on b is output to the signal line 510.

The temporary storage means 10 reads the image data supplied via the signal line 510 and stores the uncompressed data
Stored as c.

The first compression means 11 in the compression / decompression means 31
a and the second compression unit 11b compress the uncompressed data 10c using the MH compression algorithm and the MR compression algorithm in the same manner as the first compression unit 11a and the second compression unit 11b in FIG. The compression result is stored in the first compressed data 10a and the second compressed data 1
0b is written to the temporary storage means 10.

The data length counting means 12 operates in the same manner as the data length counting means 12 of FIG.
The data length of a, the data length of the second compressed data 10b, and the data length of the uncompressed data 10c are calculated and output to the signal line 514. Hereinafter, the data length of the first compressed data 10a is 10,000, the data length of the second compressed data 10b is 7000, and the data length of the uncompressed data 10c is 20,000.
The description will be made by taking the case of as an example.

The value of the counter 22b in the data selection means 22 has been initialized to zero. When the data length of the first compressed data 10a is supplied via the signal line 514, the data selecting unit 22 stores the supplied value in the data length memory 22.
a at the address A1 and the counter 22b
Is increased by one. When the data length of the second compressed data 10b is supplied via the signal line 514,
The supplied value is written to the address A2 of the data length memory 22a, and the value of the counter 22b is increased by one. Also, the uncompressed data 10c is transmitted via the signal line 514.
When the data length is supplied, the supplied value is written to the address A3 of the data length memory 22a. For example, in the example defined above, the data length of the first compressed data 10a is 1
0000, the data length of the second compressed data 10b is 700
0, since the data length of the uncompressed data 10c is 20000, as shown in Table 1A, the data length memory 22a
The address A1 has 10,000 and the address A2 has 7
000 is written to address A3. At this time, the value of the counter 22b is set to a value of 2 which is equal to the number of compression means incorporated in the compression / expansion means 31.

After that, the first expanding means 11c and the second expanding means 11d in the compressing / expanding means 31 operate in the same manner as the first expanding means 11c and the second expanding means 11d of FIG. The first compressed data 10a and the second compressed data 10b are decompressed.

The expansion time measuring means 13 measures the time required for the first expansion means 11c and the second expansion means 11d to expand the data in exactly the same manner as the expansion time measuring means 13 in FIG. The signal is output to the signal line 516 as the first extension time and the second extension time. In the following, taking the case where the first decompression time is 170 milliseconds and the second decompression time is 250 milliseconds as an example, as shown in (Table 2) A, the second decompression time is output to the signal line 516. The description will be made on the assumption that the value of the first decompression time is 170 and the value of the second decompression time is 250.

The register 22d stores the extension time measuring means 13
Stores an upper limit that is allowable as the data expansion time to be measured, and constantly outputs the stored value to the signal line 520. In the following, a case where the upper limit value of the time is 200 milliseconds will be described as an example, assuming that the value stored in the register 22d is 200 as shown in (Table 3).

When the first extension time is supplied via the signal line 516, the comparison means 22c reads the first extension time and the value supplied via the signal line 520, and compares them. As a result of the comparison, if the first extension time is smaller than the value supplied via the signal line 520, the first extension time
As a result of the comparison, a value “true value” representing one of the alternatives is output. On the other hand, if the first extension time is greater than or equal to the value provided via signal line 520,
As a first comparison result, a value “false value”, which is one of the two alternatives and represents a different value from the “true value”, is output. Also,
When the second decompression time is supplied via the signal line 516, the second decompression time and the value supplied via the signal line 520 are read, and the two are compared. As a result of the comparison, the second
Is longer than the value supplied via the signal line 520, a "true value" is output as the second comparison result. On the other hand, if the second decompression time is longer than the value supplied via the signal line 520 or they are equal, a “false value” is output as the second comparison result. For example, the first
And the second extension time (Table 2) are the values of A,
When the value stored in the register 22d and output to the signal line 520 is the value of (Table 3), as shown in (Table 4) A, the “true value” is obtained as the first comparison result, “False value” is output as the second comparison result.

When the first comparison result is output from the comparison means 22c, the data selection means 22 reads the value. If the read first comparison result is “false value”, the value of the address A1 of the data length memory 22a is changed to a special value “INVALI” indicating that the data length is invalid.
D "and reduce the value of the counter 22b by one. On the other hand, when the first comparison result is “true value”, the value of the data length memory 22a is not changed at all,
The value of the counter 22b is decreased by one. Further, when the second comparison result is output from the comparison means 22c, the value is read. If the read second comparison result is a "false value", the value of the address A2 of the data length memory 22a is rewritten to "INVALID" and the value of the counter 22b is decreased by one. On the other hand, when the second comparison result is “true value”, the value of the data length memory 22a is not changed at all, and the value of the counter 22b is decreased by one. For example, when the first comparison result and the second comparison result of (Table 4) A are supplied while the data length memory 22a stores the value of (Table 1) A, (Table 1) ) B
As shown in the figure, the value of the address A2 of the data length memory 22a is rewritten to "INVALID",
The values of 1, A3 are not rewritten. At this time, the value of the counter 22b is reduced by a total of 2 and becomes 0 as a result.

When the value of the counter 22b becomes 0 due to the decrease, the data selection means 22 reads the data length memory 22a.
Out of the addresses A1 to A3, the stored value is "I
Except for "NVALID", the address having the smallest stored value is selected. The selected address is A1
, The first compressed data 10a stored in the temporary storage means 10 is read via the signal line 517 and output as it is to the signal line 518, and the first decompression means 1
The value 1 is output to the signal line 519 as an identifier indicating 1c. On the other hand, if the selected address is A2, the second compressed data 1 stored in the temporary storage
0b is read via the signal line 517 and output as it is to the signal line 518, and the value 2 is output to the signal line 519 as an identifier indicating the second expanding means 11d. If the selected address is A3, the uncompressed data 10c stored in the temporary storage means 10 is read via the signal line 517 and output to the signal line 518 as it is, so that there is no need to expand the data. Value 3 as an identifier indicating
9 is output.

For example, in the data length memory 22a (Table 1)
When the value of B is stored, the address A1 is selected, the first compressed data 10a is output to the signal line 518, and the identifier value 1 is output to the signal line 519.

As another example, when the first extension time and the second extension time output to the signal line 516 by the extension time measuring means 13 are 220 and 190 as shown in (Table 2) B In this case, as shown in Table 4B, the first comparison result and the second comparison result output from the comparing unit 22c are “false value” and “true value”, respectively. Therefore, initially (Table 1) A
Is stored in the data length memory 22a, the value of the address A1 is rewritten to "INVALID" (Table 1), and as a result, as shown in FIG.
Is output, and the identifier value 2 is output to the signal line 519.

As another example, the extension time measuring means 1
3, the first extension time and the second extension time output to the signal line 516 are equal to 170 as shown in (Table 2) C.
In this case, assuming that the first comparison result and the second comparison result output from the comparing unit 22c are "true values" as shown in (Table 4) C, Therefore, the data length memory 22a in which the value of A (Table 1) is initially stored is not rewritten, and as a result, the second compressed data 10
b is output, and the value 2 of the identifier is output to the signal line 519.

As still another example, the extension time measuring means 1
3, the first extension time and the second extension time output to the signal line 516 by 220 as shown in (Table 2) D.
In this case, assuming that the first comparison result and the second comparison result output from the comparing unit 22c are "false values" as shown in (Table 4) D. Therefore, in the data length memory 22a in which the value of A is initially stored (Table 1), the values of the addresses A1 and A2 are both rewritten to "INVALID", and the data becomes as shown in Table 1 (D). The uncompressed data 10c is output to the signal line 518, and the identifier value 3 is output to the signal line 519.

As described above, the selecting unit 22 first specifies the decompression time from the first compressed data 10a and the second compressed data 10b generated based on the non-compressed data 10c by the register 22d. Excluding data exceeding the predetermined time and data equal to the predetermined time are excluded, and the data having the shortest data length is selected from the remaining compressed data and the uncompressed data 10c and output to the signal line 518. Outputs an identifier indicating a decompression means for decompressing the data.

The data storage means 15 stores the data supplied via the signal line 518 and the identifier supplied via the signal line 519 in association with each other.

Thereafter, the temporary storage means 10 deletes the first compressed data 10a, the second compressed data 10b, and the uncompressed data 10c.

Here, attention has been paid to one image data, and the process from the reading of the image data by the image input means 29 to the storage of the data in the data storage means 15 has been sequentially described. A plurality of images are sequentially read by the image input means 29 and the data storage means 15
Can be stored.

As described above, the data storage means 15 compresses a plurality of image data read by the image input means 29 using an algorithm which is guaranteed to be able to expand in a time shorter than the time indicated by the value of the register 22d. And
Alternatively, it is stored without being compressed.

Next, the operation at the time of reading image data will be described. The reading operation of the image data is started by the user instructing the reading of the data by the keyboard 30, and thereafter, the user operates the keyboard 30.
Is continued until a predetermined key is pressed to instruct reading stop.

Keyboard 30 outputs a character code string representing a user's instruction to signal line 530.

The read instructing means 23 determines the character code string supplied via the signal line 530, and outputs a read start command to the signal line 522 when an image read is instructed. On the other hand, when the character code string supplied via the signal line 530 is a read stop instruction, the signal line 522
To output a read stop instruction.

The timer 24 periodically repeats a data read command on the signal line 523 at predetermined time intervals during a period from the supply of the read start command via the signal line 522 to the supply of the read stop command. Output. Hereinafter, a case where the predetermined time interval is 250 milliseconds will be described as an example.

Each time a data read command is supplied via the signal line 523, the data read means 25 firstly sets the data stored in the data storage means 15 and the identifier stored correspondingly to the set. From the stored data, only one set is read via the signal line 524, and the set of the data and the identifier is output to the signal line 525 as it is. That is, first, the data storage unit 1 is first connected to the signal line 525.
5 is output, and a set of identifiers corresponding to the data stored in No. 5 is output.
The set of the data and the identifier stored second is output. In the following, an example will be described in which the reading of the set of the data and the identifier from the data storage unit 15 by the data reading unit 25 can be guaranteed to be completed within 45 milliseconds.

Image memory 26 and image memory 27
Stores white pixels that become white when data is displayed on the display unit 28 in the entire storage area as an initial value.

The compression / expansion means 31 reads a set of data and an identifier supplied via the signal line 525, and performs a process according to the value of the identifier. That is, when the value of the identifier is 1, the data is expanded by the first expansion unit 11c, and the result is output to the signal line 526 or the signal line 527.
Image memory 26 or image memory 2
7 is written. The method of determining which to write to will be described later. On the other hand, if the value of the identifier is 2, the data is expanded by the second expansion unit 11d, and the result is transmitted to either the image memory 26 or the image memory 27 via the signal line 526 or the signal line 527. Write crab. A method of determining which signal line to output will be described later. If the value of the identifier is 3, the read data is directly used as the signal line 526 or the signal line 52.
7 is written to either the image memory 26 or the image memory 27. Whether the data is to be written to the image memory 26 or the image memory 27 is determined based on the number of the data / identifier pair read from the signal line 525 regardless of the content of the read data / identifier pair. When the set is determined and the odd-numbered data and identifier pair is read, the image data is written into the image memory 26. When the even-numbered data and identifier pair is read, the image memory 2 is read.
Write to 7. Therefore, the data read first by the data reading means 25 is written to the image memory 26, and the data read second by the data reading means 25 is written to the image memory 27.

Here, it is assumed that the result of the decompression by the compression / decompression means 31 is written into the image memories 26 and 27 sufficiently faster than the data decompression time, and the time required for this is at most 5 milliseconds. Then, the following description will be given.

As already described in the description of the data storage operation, the data stored in the data storage means 15 may be compressed or expanded even if the data is compressed.
Guarantees that it can be decompressed in less than 200 milliseconds.

At this time, the data reading time of the data reading means 25 from the data storage means 15 is up to 45 times.
Milliseconds, and the maximum value of the data expansion time by the compression / expansion means 31 is 200 milliseconds.
7, the data read from the data storage means 15 is stored in the image memory at a maximum of 250 milliseconds after the timer 24 outputs the data read command to the signal line 523. 26 or image memory 2
7 will be stored.

On the other hand, the period in which the timer 24 outputs the data read command to the signal line 523 is 250 milliseconds. Therefore, after the data read command is supplied to the signal line 523 once, the time from when the next data read command is supplied is supplied. During the period, the image data read from the data storage means 15 is decompressed by the compression / decompression means 31, and the writing to the image memory 26 or the image memory 27 is completed.

When the data read command is supplied via the signal line 523, the display means 28 outputs the signal from the image memory 27 via the signal line 529 if the supplied data read command is an odd number, or a signal if the supplied data read command is an even number. The written data is read as image data from the image memory 26 via the line 528 and displayed. Therefore, when the first data read command is supplied via the signal line 523, the initial value stored in the image memory 27, that is, the full-screen white pixels are displayed, and the n-th (n ≧ 2) data When the read command is supplied, the image data read from the data storage means 15 in the (n-1) th order is displayed.

From the timer 24, a data read instruction
Since the image data is periodically supplied to the signal line 523 at 0 millisecond intervals, the image filing apparatus as a whole sequentially converts the image data stored in the data storage unit 15 in a page-turning manner in order from the first stored image data. Are periodically displayed on the display means 28 at a rate of four sheets per second.

Here, the reading of the set of the data and the identifier from the data storage means 15 is completed within 45 milliseconds,
The case where the writing of data to the image memories 26 and 27 is completed within 5 milliseconds has been described as an example. However, when these times are different, the time required to display one image in a page-turning mode is reduced to two times. The value obtained by subtracting the sum of the two times is used as the upper limit of the data expansion time in the register 22d.
May be stored.

According to the present embodiment, when compressing and storing data in the data storage means 15, a compression algorithm which can guarantee that data can be expanded within a predetermined time is used. Even when data is continuously read at a predetermined time interval, when reading of new data is started, expansion of previously read data and image memory 2 are performed.
Since the writing to 6, 27 has been completed, it is possible to continuously display image data in a page turning mode at a stable speed.

Further, it is possible to guarantee that the entire image is displayed for each image without any part being lost. Therefore, compared with the technique disclosed in Japanese Patent Application Laid-Open No. Even if a characteristic illustration or chart that is the key to search is present in the most recently displayed part, such as near the bottom of the page, that part does not end without being displayed. Can be solved.

The data storage means 15 stores, among the data compressed by an algorithm satisfying the condition that the data can be expanded within a predetermined time and the data before compression,
Since the shortest data length is selected and stored, the amount of storage medium used can be reduced.

(Embodiment 3) FIG. 3 shows a combination of a data storage device and a data reading device according to the present invention.
FIG. 2 is a block diagram illustrating a configuration of an example of the sound storage and playback device.

In FIG. 3, reference numeral 71 denotes a compression / expansion means, in which a first compression means 11a and a second compression means 11 are provided.
b, first expanding means 11c and second expanding means 11d. Reference numeral 72 denotes a data selection unit realized by a CPU (Central Processing Unit), a memory, and software. Reference numeral 72a denotes a data length memory provided in a memory included in the data selection means 72. Reference numeral 72c denotes a comparison unit included in the data selection unit 72. Reference numeral 72d denotes a register included in the data selection means 72. Also,
Reference numeral 73 denotes an extension time measuring means realized by a crystal oscillator and a frequency divider. Reference numerals 76 to 77 denote sound memories. Reference numeral 78 denotes a sound generating means, in which the D / A converter 7 is provided.
8a, an amplifier 78b, and a speaker 78c. Reference numeral 79 denotes sound input means, which has a microphone 79a, a D / A converter 79b, and a memory 79c inside. 570 to 574, 576 to 579 are signal lines.
In addition, the same components as those in FIG. 2 are denoted by the same reference numerals as those in FIG.

Table 5 shows an example of the comparison result output from the comparing means 72d.

[0122]

[Table 5]

Hereinafter, the operation of the sound storage / reproduction device will be described.
The description will be given separately for the time of storing the acoustic data and the time of reproducing the acoustic data.

First, the operation at the time of storing acoustic data will be described. The operation of storing the acoustic data is started when the user operates the keyboard 30 to instruct reading of an acoustic signal, and inputs sound to the microphone 79a.

Keyboard 30 outputs a character code string representing a user's instruction to signal line 530.

The sound input means 79 determines the character code string supplied via the signal line 530, and when instructed to read the sound, converts the sound into an acoustic signal composed of an electric signal by the microphone 79a. A / D converter 7 converts sound signal
After digitizing by 9b, the digitized sound data is written into the memory 79c.

When the user operates the keyboard 30 again,
When the end of the reading of the sound signal is instructed, the sound input means 7
At 9, the reading of the sound data from the microphone 79a to the memory 79c ends.

After that, the sound input means 79 is stored in the memory 79
The audio data stored in c is divided every 250 milliseconds of the audio signal, and the divided audio data is output to the signal line 510 one by one from the front.

The temporary storage means 10 reads the acoustic data supplied via the signal line 510, and
Stored as c.

First compression means 11 in compression / expansion means 71
a and the second compression unit 11b compress the uncompressed data 10c using the MH compression algorithm and the MR compression algorithm in the same manner as the first compression unit 11a and the second compression unit 11b in FIG. The compression result is stored in the first compressed data 10a and the second compressed data 1
0b is written to the temporary storage means 10.

The data length counting means 12 operates in the same manner as the data length counting means 12 shown in FIG.
The data length of a, the data length of the second compressed data 10b, and the data length of the uncompressed data 10c are calculated and output to the signal line 514. Hereinafter, the data length of the first compressed data 10a is 10,000, the data length of the second compressed data 10b is 7000, and the data length of the uncompressed data 10c is 20,000.
The description will be made by taking the case of as an example.

When the data length of the first compressed data 10a is supplied via the signal line 514, the data selecting means 72 compares the supplied value with the address A of the data length memory 72a.
Write to 1. When the data length of the second compressed data 10b is supplied via the signal line 514, the supplied value is written to the address A2 of the data length memory 72a.
When the data length of the uncompressed data 10c is supplied via the signal line 514, the supplied value is written to the address A3 of the data length memory 72a. For example, in the example defined above, the data length of the first compressed data 10a is 1000
0, the data length of the second compressed data 10b is 7000, and the data length of the uncompressed data 10c is 20,000.
(Table 1) As shown in A, 10000 is stored in the address A1 of the data length memory 72a, 7000 is stored in the address A2,
20000 is written to the address A3.

Next, the data selecting means 72 searches for the smallest value among the values stored in the addresses A1 to A3 of the data length memory 72a. If the value found by the search is the value stored at the address A3, that is, the data length of the uncompressed data 10c, the uncompressed data 10c stored in the temporary storage means 10 is transferred to the signal line 517. And outputs it as is to the signal line 519 as an identifier indicating that there is no need to expand the data, and terminates the data selection operation. On the other hand, the value found as a result of the search is the address A1
If the value is the data length of the first compressed data 10a, the first compressed data 10a stored in the temporary storage means 10 is read via the signal line 517, and The signal is output to a signal line 571 as an identifier indicating the first decompression means 11c. Nothing is output to the signal lines 518 to 519.
On the other hand, if the value found as a result of the search is the value stored at the address A2, that is, the data length of the second compressed data 10b, the second compressed data 10b stored in the temporary storage means 10 Is read via the signal line 517 and output as it is to the signal line 570,
The value 2 is output to the signal line 571 as an identifier indicating 1d. Nothing is output to the signal lines 518 to 519. For example, when the value of (Table 1) A is stored in the data length memory 72a, the second compressed data 10b is output to the signal line 570, and the identifier value 2 is output to the signal line 571. As a result, nothing is output to the signal lines 518 to 519.

The compression / expansion means 71 reads the data supplied via the signal line 570 and the identifier supplied via the signal line 571, and performs processing according to the value of the identifier. That is, when the value of the identifier is 1, the data is expanded by the first expansion unit 11c using the MH expansion algorithm. The data generated as a result of the decompression is not necessary here, and is discarded. When data expansion is started, an expansion start signal is sent to a signal line 573.
, And outputs an expansion end signal to the signal line 573 when the expansion is completed. On the other hand, if the value of the identifier is 2, the data is expanded by the second expansion unit 11d using the MR expansion algorithm. The data generated as a result of the decompression is not necessary here, and is discarded.
In addition, an expansion start signal is output to a signal line 573 when data expansion is started, and an expansion end signal is output to a signal line 573 when expansion is completed.

When the expansion start signal is supplied via the signal line 573, the expansion time measuring means 73 sets the initial value to 0 and starts measuring the time elapsed thereafter. The time is measured in milliseconds. The measurement result is continuously output to the signal line 574 as the expansion time until the expansion end signal is supplied via the signal line 573. For example, the value output to the signal line 574 becomes 10 when 10 milliseconds have elapsed after the supply of the expansion start signal, and the value output to the signal line 574 becomes 25 when 15 milliseconds have elapsed thereafter. Become. The expansion time measuring means 73 stops measuring the expansion time and outputting the measured value to the signal line 574 when the expansion end signal is supplied via the signal line 573.

The register 72d is provided with a decompression time measuring means 73.
Stores an upper limit value that can be tolerated as a data expansion time to be measured, and constantly outputs the stored value to the signal line 520. In the following description, the upper limit of this time is 200
Taking milliseconds as an example, description will be made assuming that the value stored in the register 72d is 200 as shown in (Table 3).

During the period in which the extension time is supplied via the signal line 574, the comparing means 72d always reads the extension time and the value supplied via the signal line 520, and compares them. If the result of the comparison indicates that the decompression time is not equal to the value supplied via signal line 520, nothing is output. On the other hand, when the extension time becomes equal to the value supplied via the signal line 520, a “false value” is output as the comparison result. In addition, when the expansion end signal is supplied via the signal line 573, the expansion time supplied to the signal line 574 immediately before that is compared with the value supplied via the signal line 520. As a result of the comparison, if the extension time is smaller than the value supplied via the signal line 520, a "true value" is output as the comparison result. On the other hand, if the extension time is greater than the value supplied via the signal line 520 or the two are equal, it is regarded that the comparison result has already been output as a “false value” and no new output is performed. do not do. For example, it takes 250 milliseconds for the compression / expansion means 71 to decompress the compressed data 10b to the end (Table 2), and the value stored in the register 72d is 200 as shown in (Table 3). Assuming a certain case, 200 milliseconds after the compression / decompression means 71 starts decompression of the compressed data 10b, that is, before the decompression is completed, as shown in (Table 5), a "false value" is obtained as a comparison result. Is output.

When the comparison result is output from the comparison means 72c, the data selection means 72 reads the value. If the read comparison result is “true value”, the data output to the signal line 570 and the identifier output to the signal line 571 are output to the signal lines 518 and 519 as they are, and the data selection operation ends. I do. On the other hand, when the comparison result is “false value”, the value stored in the data length memory 72a is searched and found earlier, and the value is set to “IN”.
VALID ”and outputs a decompression stop command to the signal line 572. For example, the data length memory 72
When “a” stores the value of A in (Table 1) and “fake value” is output from the comparing unit 72c as a comparison result as in (Table 5), As shown in the memory 62
The value of the address A2 of “a” is rewritten to “INVALID”, and the values of the addresses A1 and A3 are not rewritten.

When the compression / decompression means 71 is supplied with the decompression stop command via the signal line 572, the compression / decompression means 71 stops the decompression operation using the first decompression means 11c or the second decompression means 11d at that time. , And outputs a decompression stop signal to the signal line 573. For example, assuming that it takes 250 milliseconds to complete the expansion of the second compressed data 10b as shown in (Table 2) A, the expansion stop command is issued via the signal line 572 200 milliseconds after the start of the expansion. Is supplied to the signal line 573, which is five times that when the extension operation is not stopped halfway.
An expansion end signal is output 0 ms earlier.

Thereafter, the data selection means 72 searches again for the smallest one of the values stored in the addresses A1 to A3 of the data length memory 72a, except for the one which is "INVALID". If the value found as a result of the search is the value stored at the address A3, that is, the data length of the uncompressed data 10c, the uncompressed data 10c stored in the
The data is read out via the line 17 and output as it is to the signal line 518, the value 3 is output to the signal line 519 as an identifier indicating that the data does not need to be expanded, and the data selection operation ends. On the other hand, if the value found as a result of the search is the value stored at the address A1, that is, the data length of the first compressed data 10a, the first compressed data 10a stored in the temporary storage Is read via the signal line 517 and output as it is to the signal line 570, and the value 1 is output to the signal line 571 as an identifier indicating the first decompression means 11c. Nothing is output to the signal lines 518 to 519. On the other hand, if the value found as a result of the search is the value stored at the address A2, that is, the data length of the second compressed data 10b, the second compressed data 10b stored in the temporary storage means 10 Is read via the signal line 517 and output as it is to the signal line 570,
The value 2 is output to the signal line 571 as an identifier indicating d.
Nothing is output to the signal lines 518 to 519. For example, when the value of (Table 1) B is stored in the data length memory 72a, the value found by the search is 10000, and the value is stored at the address A1. Outputs the first compressed data 10a, and outputs the identifier value 1 to the signal line 571.

Thereafter, the expansion operation by the compression / expansion means 71, the measurement by the expansion time measuring means 73, and the comparison by the comparing means 72d are performed again on the first compressed data 10a, and the comparison result is output. . The data selection unit 72 determines data to be output to each signal line based on the value output from the comparison unit 72c.

As described above, the data selection means 72,
Compression / expansion means 71, expansion time measurement means 73, comparison means 7
The operation of 2d is summarized as follows. First, the data selection unit 72 compares the data lengths of the first compressed data 10a, the second compressed data 10b, and the uncompressed data 10c supplied from the data length counting unit 12 via the signal line 514 with a data length memory. 72a. Then, the first compressed data 10a, the second compressed data 10b, and the uncompressed data 10c are searched for the one having the shortest data length. If the retrieved data is the uncompressed data 10c, the identifier corresponding to the uncompressed data 10c is output to the signal lines 518 and 519, and the operation is terminated. On the other hand, if the retrieved data is the first compressed data 10a or the second compressed data 10b, it is expanded by the compression / expansion means 71, and the time required for the expansion is measured by the expansion time measuring means 73. . Further, the expansion unit 72d compares the expansion time with the upper limit value stored in the register 72d which is allowable as the expansion time. Then, as a result of the comparison, if the decompression time is smaller than the upper limit value allowable as the decompression time, the same data as the data decompressed by the compression / decompression means 71 is output to the signal line 518, and the corresponding identifier is signal line 519 is output to end the operation. On the other hand, when the decompression time has reached the upper limit allowable as the decompression time, the compression / decompression means 71 stops the decompression operation at that stage. The above operation is performed in order from the data having the shortest data length, and finally, the compressed data which can be expanded within a predetermined time or the uncompressed data 10c having the shortest data length is transmitted as a signal. Line 5
18 and the identifier corresponding to the data is output to the signal line 519, and the operation is completed.

The data storage means 15 stores the data supplied via the signal line 518 and the identifier supplied via the signal line 519 in association with each other.

Thereafter, the temporary storage means 10 deletes the first compressed data 10a, the second compressed data 10b, and the uncompressed data 10c.

Here, attention has been paid to one acoustic data, and the process from the output of the acoustic data to the signal line 510 by the acoustic input means 79 to the storage of the acoustic data in the data storage means 15 has been sequentially described. The storage / reproduction device sequentially outputs the sound data stored in the memory 79c to the signal line 510, and performs the above storage operation until the sound signal input from the microphone 10a is completely stored in the data storage unit 15 as sound data. Execute repeatedly.

Next, the operation at the time of reading acoustic data will be described. The operation of reading the acoustic data is started by the user instructing the reading of the data by the keyboard 30, and thereafter, the user operates the keyboard 30.
Is continued until a predetermined key is pressed to instruct reading stop.

[0147] Keyboard 30 outputs a character code string representing a user's instruction to signal line 530.

The read instruction means 23 determines the character code string supplied via the signal line 530, and outputs a read start command to the signal line 522 when the instruction to read the acoustic data is issued. On the other hand, if the character code string supplied via the signal line 530 is a read stop instruction, the signal line 5
A read stop instruction is output to 22.

The operations of the timer 24 and the data reading means 25 are exactly the same as the operations of the timer 24 and the data reading means 25 in FIG.

In the acoustic memories 76 and 77, a value representing a silent state in an initial state is stored at all addresses.

Compression / expansion means 71 when reading acoustic data
Is compared with the operation of the compression / expansion means 11 in FIG.
Instead of writing data to the image memory 26 via the signal line 526, data is written to the acoustic memory 76 via the signal line 576, and instead of writing data to the image memory 27 via the signal line 527, via the signal line 577. Except for writing data into the acoustic memory 77, the details are omitted because they are exactly the same, but the data is stored in the acoustic memories 76 and 77 at 250 millisecond intervals, as in the case of the second embodiment in FIG. The acoustic data stored in the storage means 15 is
It is written after being decompressed as necessary.

When the data read command is supplied via the signal line 523, the sound generating means 78 outputs the signal from the acoustic memory 77 via the signal line 579 if the supplied data read command is an odd number, and if the data read command is an even number, After reading the written data from the acoustic memory 76 via the signal line 578 and converting it into an analog signal by the D / A converter 78a,
The signal is amplified by the amplifier 78b and the amplified signal is supplied to the speaker 78c.
To generate sound. Therefore, when the first data read command is supplied via the signal line 573, the initial value stored in the sound memory 77, that is, data representing a silent state is read and no sound is generated.
When the n-th (n ≧ 2) data read command is supplied, the n−1-th acoustic data read from the data storage unit 15 is output from the speaker 78c as sound.

Here, the data stored in the data storage means 15 is input from the microphone 79a, and is input to the A / D converter 7
The sound data digitized by 9b is stored separately for every 250 milliseconds. To make one data read out from the data storage means 15 sound as sound using the speaker 78c, the sound data is stored for 250 milliseconds. Takes time.
On the other hand, the data read command is periodically supplied from the timer 24 to the signal line 523 at an interval of 250 milliseconds.
The audio data divided and stored every 50 milliseconds is continuously output without interruption or skipping, as if all the audio data were continuously stored without being divided. It can sound at 78c.

According to the present embodiment, the sound data input from the sound input means 79 is compressed by an algorithm which can guarantee that the sound data can be expanded within a predetermined time from among a plurality of compression methods. , The amount of storage medium used by the data storage means 15 can be reduced as compared with the case where the data is stored without compression. In addition, after the audio data is divided at predetermined time intervals, the compression algorithm with the shortest data length that can guarantee that the individual data can be expanded within the predetermined time is selected. Even when compared to the case where the whole is compressed together with one algorithm, the silence part is an algorithm suitable for the silence state, and the part with many high frequency components is an algorithm suitable for it, and so on.
Each part can be compressed by an algorithm suitable for that part, and the amount of storage media used in the data storage means 15 can be reduced. Also, audio data that cannot be expanded within a predetermined time by using any of the compression algorithms is stored in the data storage unit 15 in a format without being compressed. Also, it is possible to guarantee that the data stored in the data storage means 15 can be read out as decompressed data in the acoustic memories 76 and 77 within a predetermined time, so that the data is divided into a plurality at predetermined time intervals. While the sound data stored and stored is reproduced by the speaker 78c, the next sound data is read out from the data storage means 15 and expanded,
The sound data can be stored in the sound memories 76 to 77, and the sound data divided and stored in the data storage unit 15 is
As if all the sound data were continuously stored without being divided, the sound can be continuously output from the speaker 78c without interruption or skipping.

Further, the data selecting means 7 in the present embodiment.
2 indicates that the data storage means 15 stores the data in the data storage means 15 after the measurement of the expansion time performed by the compression / expansion means 71 and the expansion time measurement means 13 is completed for both the first compressed data 10a and the second compressed data 10b. Instead of selecting the data to be stored, instead of selecting the compressed data in which it is first found that the data decompression time is shorter than the predetermined time, the data is selected as compared with the data selection unit 22 in the image filing apparatus of the second embodiment. Data can be selected at high speed.
In addition, since the measurement of the decompression time is performed in order from the compressed data having the short data length, the compression algorithm that can first confirm that the decompression time is shorter than the predetermined time is the algorithm that minimizes the data length. Can be guaranteed. Further, when it is detected by the decompression time measuring means 13 and the comparing means 72c that the decompression time has reached a predetermined time, the compression / decompression means 71 stops the decompression of the subsequent data, and determines the decompression time of another compressed data. Since the measurement is started, it is possible to select data to be stored in the data storage unit 15 at higher speed.

The present invention is not limited to the above embodiment, but can be carried out with appropriate changes within the scope of the present invention.

For example, in each embodiment, the data storage means 15 may be realized using a storage medium other than an optical disk, such as a hard disk or a flash memory.

Similarly, the temporary storage means 10 may be realized using a storage medium other than a hard disk, such as a semiconductor memory or a floppy disk, or the data storage means 15
It may be realized by using a part of the storage medium therein. In particular,
When the temporary storage means 10 is realized by using a part of the data storage means 15, the decompression time measurement means includes not only the time required for decompression of the compressed data by the compression / decompression means 11, 31, 71 but also the time prior to that. The measurement may include the time required for reading the compressed data from the temporary storage means 10. With this configuration, the total time required for reading and decompressing data is set within a predetermined time, taking into account fluctuations in the data reading time from the data storage unit 15 due to fluctuations in the data length due to compression. -It is possible to select a decompression algorithm. When the temporary storage means 10 is realized by using a part of the data storage means 15, the data selected by the data selection means 14, 22, 72 is stored again in the data storage means 15, and the temporary storage means Instead of erasing the data stored in 10, it is a matter of course that only the data selected by the data selecting means 14, 22, 72 may be left and the unselected data may be erased.

Further, the extension time measuring means 13 may be realized by using an AC frequency of a commercial power supply instead of the crystal oscillator.

In the first to third embodiments, the first
The compression algorithm used by the compression means 11a and the second compression means 11b is a compression algorithm based on the LZ method,
JBIG (Joint Bi-level Image coding experts Grou
p) Compression algorithm, MMR (Modified Modified Relative) used for facsimile of International Standard Group 4
MH, M, compression algorithms, compression algorithms for color images JPEG, compression algorithms for subband coding suitable for audio signals, etc.
A compression algorithm other than R may be used. In this case, it is natural that the expansion algorithm used by the first expansion unit 11c and the second expansion unit 11d is changed to one corresponding to the compression algorithm. The compression / expansion means 11 and the compression / expansion means 71 having these inside
It may be realized by a PU and software, or three or more compression / decompression algorithms to be applied may be provided.

The sound input means 79 in the sound storage / reproducing apparatus of the third embodiment is provided with a sound reproducing apparatus such as a tape recorder, a record player, a CD player or the like instead of the microphone 79a. The music may be provided to the D / A conversion means 79b.

The image input unit 19 in the data storage device of the first embodiment and the image input unit 29 of the image filing device of the second embodiment may read a multi-tone monochrome image or read a color image. You may do so. Instead of reading an image from paper with a scanner, an image may be read from another medium such as a movie film. In such a case, it goes without saying that the compression / decompression algorithm used by the compression / decompression means 10 is selected according to the properties of the image.
In particular, where there is a strong correlation between adjacent images, such as in motion picture film, MPEG should be included in one of the compression algorithms.

In the image filing apparatus according to the second embodiment, the display speed of the page turning mode may be lower or higher than four sheets per second, or a dial used for a microfilm reading apparatus may be added. Alternatively, the speed may be set. In particular, when an image filing apparatus is realized using high-speed hardware, a display speed of about 30 images per second can be set, and one frame of a moving image such as a movie or a television broadcast is stored in sequence. A moving image may be displayed by displaying the page turning mode. In this case, the sound storage / reproducing apparatus of the third embodiment is built in, so that sound and music such as a movie and a television broadcast are also stored, so that the moving picture and the sound / music can be reproduced simultaneously, so-called VTR player or laser disk player. May be used instead of conventional AV equipment.

Further, the image filing apparatus according to the second embodiment uses the same technology as the conventional apparatus to set an attribute to image data when storing the image data and to set an attribute when reading the image.
Only the image data having the desired attribute may be extracted, and only the extracted image data may be read.

[0165]

As described above, as shown using various examples,
According to the present invention, which compression algorithm is to be stored in the data storage means is determined based on not only the count result of the data length count means but also the measurement result of the decompression time measurement means. Instead of simply storing the data compressed by the compression algorithm having the shortest data length in the storage means, the data is selected and stored in consideration of both the data length and the time required for decompressing the data. It is possible to realize a data storage device for storing in a means.

Further, it is possible to guarantee that the data stored in the data storage means can be expanded within the allowable time.

Further, among the compression algorithms that can be expanded within the allowable time, data compressed by the algorithm having the shortest data length is stored in the data storage means, and the storage medium can be used effectively. .

In the case where all the compressed data is expanded by causing the expansion means to expand only the compressed data whose data length is shorter than the data before compression. Faster than
It is possible to determine which algorithm is used to store the compressed data in the data storage means.

Further, the data selecting means selects the data in which the time measured by the decompression time measuring means is first detected to be smaller than the upper limit allowable as the decompression time. It is possible to determine whether to store the data in the data storage unit at a higher speed.

Further, the data selecting means expands the compressed data to the expanding means in ascending order of the data length, so that the time measured by the expanding time measuring means is smaller than the upper limit value allowable as the expanding time. Can be assured that the data length firstly detected after compression is the shortest, so that it is possible to more quickly determine which algorithm is used to store compressed data in the data storage means.

When the time measured by the extension time measuring means exceeds an allowable upper limit value for the extension time,
By terminating the decompression of the data by the decompression means and starting the decompression of the new compressed data, faster than starting the decompression of the new compressed data by waiting for the completion of the decompression of the previous data, It is possible to determine which algorithm is used to store the compressed data in the data storage means.

When the time measured by the decompression time measuring means is larger than the upper limit allowable for the decompression time, any data which is not decompressed and which should not be compressed is stored in the data storage means. By selecting as, for any data,
It is possible to guarantee that the expansion is completed within the allowable time.

When the data length counted by the data length counting means is larger than the data length before compression of any of the compressed data, by selecting data not to be compressed, the data length is reduced by compression. On the contrary, it is possible to prevent the size from becoming large.

Also, since the image is optically read by the image input means and the image data generated by photoelectric conversion is compressed by the compression means, it is guaranteed that the optically read image can be expanded within the allowable time. The data is compressed by the algorithm and can be stored in the data storage means.

Further, since the sound signal obtained by converting the sound into the electric signal by the sound input means is compressed by the compression means, the sound is compressed by an algorithm which is guaranteed to be able to be expanded within an allowable time and stored in the data storage device. It becomes possible.

According to the data reading device of the present invention,
Data storage means for reading out data compressed by the selected algorithm and an identifier indicating a method for decompressing the data by individually confirming that the data can be expanded within a predetermined time among a plurality of different compression algorithms. , The read data is expanded by expansion means in accordance with the identifier, the expanded data is converted into information recognizable by human senses, and can be presented to a human at predetermined time intervals.

Further, the data stored in the data storage means includes image data, and an image is displayed by the display means in the conversion means, so that the data stored in the data storage means is converted into a continuous image by human beings. It can be presented.

Further, continuous images can be displayed at regular time intervals by the display means, and can be displayed as moving images.

By outputting the sound data stored in the data storage means to the sound generation means at a time interval equal to the sampling cycle used for storing the sound, the stored sound is regarded as a correct sound. Can be presented.

[Brief description of the drawings]

FIG. 1 is a block diagram of a data storage device according to an embodiment of the present invention.

FIG. 2 is a block diagram of an image filing apparatus combining a data storage device and a data reading device according to another embodiment of the present invention.

FIG. 3 is a block diagram of a sound storage / reproduction device in which a data storage device and a data reading device are combined in another embodiment of the present invention.

[Explanation of symbols]

 11a first compression means 11b second compression means 11c first decompression means 11d second decompression means 12 data length counting means 13, 73 decompression time measurement means 14, 22, 72 data selection means 15 data storage means 19, 29 image input means 22c, 72c comparison means 28 display means 29 image input means 78 sound generation means 79 sound input means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H03M 7/30 H04N 1/413 H04N 5/92

Claims (15)

(57) [Claims] 1. Compression means for compressing data with a plurality of different compression algorithms, decompression means for decompressing data compressed by each compression algorithm, and decompression time measurement for measuring the time required for decompression of the compressed data Means, data length counting means for counting the data length of the compressed data,
Data selecting means for selecting one of the compressed data based on the measurement result of the decompression time measuring means and the counting result of the data length counting means, and a data storage means for storing the data selected by the data selecting means A data storage device comprising: 2. The data selecting means has comparing means for comparing the time measured by the decompressing time measuring means with an upper limit allowable as the decompressing time, and the comparison result of the comparing means and the counting result of the data length counting means. 2. The data storage device according to claim 1, wherein data is selected based on the data. 3. The data selecting means selects the data having the shortest data length counted by the data length counting means from the data whose time measured by the decompression time measuring means is smaller than an upper limit value allowable as the decompression time. The data storage device according to claim 2 having a configuration. 4. The data storage device according to claim 2, wherein the data selection means expands only the compressed data having a data length shorter than the data before compression by the expansion means. 5. The data storage device according to claim 4, wherein the data selection means selects data which is first detected that the time measured by the expansion time measuring means is smaller than an allowable upper limit of the expansion time. . 6. The data storage device according to claim 5, wherein said data selection means expands the compressed data to said expansion means in ascending order of data length. 7. The data storage device according to claim 2, wherein when the time measured by the expansion time measuring means exceeds an allowable upper limit value for the expansion time, the expansion of the data by the expansion means is terminated. 8. The data selection means for selecting data before compression when the time measured by the decompression time measurement means is larger than an allowable upper limit of the decompression time for any of the compressed data. Item 3. The data storage device according to Item 2. 9. A data selecting means for selecting data before compression when any of the compressed data has a data length counted by the data length counting means larger than the data length of the data before compression. The data storage device according to claim 1. 10. The data storage device according to claim 1, further comprising image input means for optically reading an image, and photoelectrically converting the generated image data to a compression means. 11. The data storage device according to claim 1, further comprising an audio input means for compressing an audio signal generated by converting a sound into an electric signal by a compression means. 12. A method of individually confirming that data can be expanded within a predetermined time among a plurality of different compression algorithms, and storing data compressed by the selected algorithm together with an identifier indicating a data expansion method. Data storage means, read means for reading compressed data and a corresponding identifier from the data storage means, expansion means for expanding data read by the read means in accordance with the read identifier, and expansion means A data reading device comprising a conversion means for converting data decompressed by the method into information recognizable by human senses at predetermined time intervals. 13. The data reading apparatus according to claim 12, wherein the data stored in the data storage means includes image data, and the conversion means has a display means for displaying an image. 14. The data reading device according to claim 13, wherein the display means displays an image as a moving image. 15. The data reading device according to claim 12, wherein the data stored in the data storage means includes sound data, and the conversion means has sound generation means for generating sound.