JPH0691618B2 - Image data recording / reproducing device - Google Patents

Description

The present invention relates to an apparatus for recording and reproducing image data.

2. Description of the Related Art When recording image data, a recording medium having a high recording speed and a large recording capacity is required because the amount of data is very large. A hard disk can be mentioned as a high-speed and large-capacity recording medium, but it has a drawback that it is very expensive. On the other hand, loading a program of a personal computer as a recording medium that is inexpensive and has a large recording capacity,
Examples include cassette tapes used for saving.

Hereinafter, an example of a data recording / reproducing apparatus using the conventional cassette tape described above will be described with reference to the drawings.

FIG. 3 shows a conventional data recording / reproducing apparatus using a cassette tape. In FIG. 3, 1 is an image reading device,
2 and 6 are interface circuits for input / output, 3 is FSK
A modulation / demodulation circuit, 4 an equalizer circuit, 5 a recording / reproducing head, 7 a display for display, 8 a printer, and 9 a recording / reproducing device.

With respect to the data recording / reproducing apparatus configured as described above,
The operation will be described below.

First, the image signal read by the image reading device 1 is converted into a binary signal representing white and black by the interface circuit 2, frequency-modulated by the FSK modulation / demodulation circuit 3, and then passed through the equalizer circuit 4 and the recording / reproducing head 5. Recorded on a cassette tape. In the case of reproduction, the reverse operation is performed, and the data recorded on the tape is reproduced by the recording / reproducing device 9 and is output to the terminal device such as the display 7 for display or the printer 8 via the interface circuit 6. .

Problems to be Solved by the Invention However, in the above-mentioned configuration, the band is smaller than that of the baseband signal due to FSK modulation and recording on the tape.
At present, it is used at a recording speed of about 1200 bits / second due to the frequency characteristics of the tape. Therefore, when used as an image data recording / reproducing apparatus, there is a problem that the recording time is too long.

In view of the above problems, the present invention provides an image data recording / reproducing apparatus for recording image data on an inexpensive cassette tape.

Means for Solving the Problems In order to solve the above problems, the image data recording / reproducing apparatus of the present invention divides the image data into blocks having a certain length, and the data in the blocks are all in the same state. At the time, the code indicating the state and the code indicating the number of blocks in the continuous state are output at a slow bit rate, and when in a state other than the states, the data in the block is directly converted to a predetermined code. And output at a high bit rate.

The present invention enables the image data to be recorded / reproduced on the inexpensive cassette tape at high speed and without any error by the above-mentioned method.

Embodiment An image data recording / reproducing apparatus according to an embodiment of the present invention will be described below with reference to screens.

FIG. 1 is a block diagram of an image data recording / reproducing apparatus according to an embodiment of the present invention. In FIG. 1, 10
Is an image reading device, 11 is a read image signal white,
An interface circuit for converting to black binary data, 12 and 25 are buffer memories, 13 is data whether the data in the divided blocks are all white, all black, or a mixture of white and black. An identification circuit for identifying and outputting a signal representing those states, 14 is a counter for counting how many blocks the state lasts if the data in the block is all white or all black, and 15 is a block If the data in the block is mixed in black and white (for example, Manchester code), it is output at a high bit rate, and if the data in the block is all white or all black, how many blocks the state continues in the code indicating the state A code generation circuit that adds a code that represents the code length and outputs a code that makes the code length equal to the code created when black and white are mixed at a slow bit rate. A synchronous clock generation circuit for generating a clock equal to the code length generated by the code generation device 15, 17 a recording head drive circuit, 18 a data signal recording head, 19 a synchronous clock recording head, 20 a data signal reproduction Head, 21 is a synchronous clock reproducing head, 22 is a data signal reproducing circuit, 23 is a synchronous clock signal reproducing circuit,
Reference numeral 24 is an image data recovery circuit for recovering the original image data from the code of one block length reproduced by the data signal reproduction device 22 and the synchronous clock reproduced by the synchronous clock reproduction circuit 23, and 26 is for display. An interface circuit for outputting to the terminal device of the display 27 or the printer 28 for printing, 29 is a recording unit, and 30 is a reproducing unit.

The operation of the image data recording / reproducing apparatus configured as described above will be described with reference to FIGS. 1 and 2.

First, the recording operation will be described. Image reader 10
The image signal (FIG. 2 (a)) read by is converted into binary data of white or black by the interface circuit 11 (FIG. 2 (b)) and then stored in the buffer memory 12. The image data stored in the buffer memory 12 is input to the discriminating circuit 13 by a predetermined length, for example, by 1 byte, and the discriminating circuit 13 determines whether the inside of each block is all white, all black, or white. Identify whether black and black are mixed. When all are white, the counter 14 is incremented by 1 and the next one block is read into the identification circuit 13.

This operation is repeated until a block that is not all white is detected, the number of consecutive white blocks is counted, and then a signal representing white (Fig. 2 (c)) and the number of the blocks (Fig. 2 (d) ), Equal to the output of the counter 14) is output to the code generation circuit 15. When all of one block is black, the signal representing black (FIG. 2 (c)) and the number of blocks are output to the code generation circuit 15 in the same manner. When white and black are mixed in one block, the signal (FIG. 2 (c)) indicating the mixture of white and black and one block data are output to the code generation circuit 15 as they are. In the code generation circuit 15, when a signal representing a state in which white and black are mixed is detected, the data is directly converted into a Manchester code and output at a high bit rate, and when a signal representing a state of all white is detected, it is represented. After the code, the number of consecutive white blocks is added by the Manchester code, and the code (FIG. 2 (e)) having the same length as the code generated when black and white are mixed is output at a slow bit rate. However, when a signal indicating the state of all black is detected, it is generated in the same manner when the length of black and white is mixed by adding the number of blocks of continuous black by the Manchester code after the code indicating black. A code equal to the code length (FIG. 2 (e)) is output at a slow bit rate. It should be noted that the above-mentioned code representing white and the code representing black are assigned patterns which are not included in the Manchester code. The code generated as described above and the clock pulse (FIG. 2 (f)) generated by the synchronous clock generation circuit 16 are used for the recording head drive circuit 17,
Data signal recording head 18, synchronous clock recording head
Recording on each individual track via 19.

Next, the reproducing operation will be described. The signals read by the data signal reproducing head 20 and the synchronous clock reproducing head 21 are reproduced by the data signal reproducing circuit 22 and the synchronous clock reproducing circuit 23, and the image data is restored by the image data restoring circuit 24. The restored image data is stored in the buffer memory 25 and then output via the interface circuit 26 to terminals such as the display 27 for display and the printer 28.

As described above, according to the present embodiment, the input image data is divided into blocks of a certain length, and when the data in the blocks are all white or all black, the data is added after the code indicating the state. The amount of data is output by outputting a code indicating the number of blocks in which the state is continuous, and if the data in the block is a mixture of white and black, the data in the block is directly converted to a predetermined code and output. Since the signal is compressed and the signal can be recorded as it is as a baseband signal, it can be recorded and reproduced on a cassette tape at high speed.

Further, according to the present embodiment, the bit rate is low for the coded block and high for the block in which the raw data is converted into a predetermined code as it is, so that an error occurs. Error can be reduced for coded blocks that have a large effect on the entire image data, and further recorded for blocks of raw data that do not significantly affect the entire image data even if there are some bit errors. The reproduction time can be shortened, and recording and reproduction can be performed on the cassette tape at a higher speed.

It should be noted that the error can be further reduced by adding an error correction bit to the coded block in this embodiment.

Further, although the case where the cassette tape is used has been described in the present embodiment, it may be an open reel tape or a micro cassette tape.

Further, although the synchronous clock is recorded and reproduced on the second track of the tape in the present embodiment, the clock signal may be reproduced from the data signal recorded on the first track without recording on the tape. .

Further, in the present embodiment, the synchronous clock was recorded on the second track of the tape and the data signal was recorded on the first track, but the synchronous clock and the data signal are recorded in parallel on the other tracks as well. Further, the recording speed can be increased.

Further, although the recording unit 29 and the reproducing unit 30 are shown separately in this embodiment, they are shown separately for the sake of explanation, and there are actually circuits which are commonly used by the recording unit and the reproducing unit.

As described above, the present invention divides the input image data into blocks of a certain length, and when the data in the blocks are all white or all black, follow the code indicating the state. , A code indicating how many blocks the state is continuous is added and output at a slow bit rate, and if the data in the block is a mixture of white and black, the data in the block is directly converted to a predetermined code. By converting and outputting at a high bit rate, image data can be compressed and recorded / reproduced on a cassette tape at high speed and without error.

Also, if the data in a block is all white or all black, a code that indicates how many blocks the state continues and if the data in the block is a mixture of white and black, each data is directly expressed by Manchester code. As a result, the baseband signal can be recorded on the tape at high speed without the need for so-called modulation operation.

[Brief description of drawings]

FIG. 1 is a block diagram of an image data recording / reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a waveform diagram showing signal waveforms of respective parts in FIG. 1, and FIG. 3 is a block diagram of a conventional data recording / reproducing apparatus. Is. In FIG. 1, 10 ... Image reading device, 11 ... Interface circuit, 12 and 25 ... Buffer memory, 13 ...
… Identification circuit, 14 …… Counter, 15 …… Code generator circuit, 16
...... Synchronous clock generation circuit, 17 …… Recording head drive circuit, 18 …… Data signal recording head, 19 …… Synchronous clock recording head, 20 …… Data signal reproducing head, 21…
… Synchronous clock reproducing head, 22 …… Data signal reproducing circuit, 23 …… Synchronous clock reproducing circuit, 24 …… Image data restoration circuit, 26 …… Interface circuit, 27 …… Display, 28 …… Printer, 29 …… Recording unit, 30 ... Playback unit.

Claims (2)

[Claims] 1. When image data is input, the image data is divided into blocks of a fixed length, and when all the data in the block is white, it represents a code representing white and the number of consecutive white blocks. The code and the code are output at a slow bit rate, and when all black, the code that represents black and the code that represents the number of consecutive black blocks are output at a slow bit rate, and when white and black are mixed, the raw An image data recording / reproducing apparatus comprising: means for converting data into a predetermined code as it is and outputting at a high bit rate; and means for outputting a signal indicating a division of each of the encoded blocks. 2. A bit for error correction is added to a coded block, and a block for which raw data is directly converted into a predetermined code is output without adding a bit for error correction. The image data recording / reproducing apparatus according to claim 1, wherein