JPH0454655A - Information recording/reproducing device - Google Patents

Abstract

PURPOSE:To exactly execute the error detection of information data at the time of reproduction by calculating and adding an odd number/even number parity of this data in addition of a parity byte by a product code, at the time of recording the information data. CONSTITUTION:At the time of recording information data, to its information data, product code parities C1, C2 and an odd number/even number parity byte 51 are added and recorded. When read-in of the data is executed from a disk device 112, it is instructed to an odd number/even number parity calculating part 109, and an odd number/even number parity based on its reproduced data is calculated. Subsequently, a value of the calculated odd number/even number parity and a value of an odd number/even number parity read out actually from the disk device 112 are compared. When both of them coincide with each other, the reproduced data read out of the disk 112 is decided to be no-error, and sent out to a host computer 101. On the other hand, in the case both the values do not coincide with each other, for instance, it is detected that an error such as a byte shift, etc., is generated, and a prescribed error processing is executed. As a result, an error detection of information data at the time of reproduction is executed exactly.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an information recording and reproducing apparatus that adds a product code and odd/even parity to information data to detect and correct errors in information data.

[Conventional technology]

Conventionally, an information recording/reproducing apparatus using a product code is shown in FIG.
), it is configured to detect and correct errors in information data using parity in the C2 direction, for example. Generally, when two linear codes C1 and C2 are given, these two codes are defined as (nl, 1) code and (n2°k,) code, respectively. These codes are shown in Figure 6 (
If it is arranged two-dimensionally as shown in B) and encoded with C1 in the row direction and 02 in the column direction, linear (n r n * +
1 to 2) sign is obtained. This code is called a product code.

[Problem to be solved by the invention]

However, in the conventional example shown in FIG. 6(A), C
Only the comparison between the information data in the two directions and the C2 parity created and added based on the information data in the C2 direction is performed. For this reason, for example, if a data mark is erroneously detected during data reproduction and a byte shift of information data occurs as a result, there is a drawback that this cannot be detected. The present invention has been made in view of the above-mentioned conventional example, and when recording information data, in addition to the parity byte using the product code, the odd/even parity of this data is calculated and added. It is an object of the present invention to provide an information recording and reproducing device that can accurately detect errors.

[Means to solve the problem]

In order to achieve the above object, the information recording/reproducing apparatus of the present invention has the following configuration. That is, an odd/even parity calculation means for calculating an odd/even parity code of the information data based on the information data, an odd/even parity code calculated by the odd/even parity calculation means, and a parity byte based on a product code. a recording means for adding the information data to the information data and recording it on a recording medium; a reading means for reading the information data together with the parity byte and the odd/even parity code from the recording medium; and information read by the reading means. Based on the data odd/
Comparing means is provided for comparing the odd/even parity code calculated by the even parity calculating means and the odd/even parity code read by the reading means.

[Effect]

In the above configuration, an odd/even parity code of the information data is calculated based on the information data, and the calculated odd/even parity code and a parity byte based on the product code are added to the information data and recorded on the recording medium. do. The information data is read from this recording medium along with its parity byte and odd/even parity code, and the odd/even parity code calculated based on the read information data is compared with the read odd/even parity code. Check whether an error has occurred in the information data read out.

【Example】

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. <Explanation of recorded data examples (Fig. 3 to Fig. 5)> Fig. 3 shows information data during disk recording, product code parity CI, C
FIG. 2 is a diagram showing recording directions of odd/even parity data for 2 and data. In the figure, the block surrounded by the smallest opening represents one byte. FIG. 4 is a diagram showing a state in which the odd/even parity shown in FIG. 3 is actually recorded. Here, when recording information data, the information data includes product code parity C1, C2 and odd/even parity bytes 5.
An example of recorded data with 1 added thereto is shown. Each of the parities P1 to P7 of this parity byte 51 corresponds to the parities P1 to P7 in FIG. When reproducing information data as described above, if there is no erroneous detection of data marks and the data can be reproduced normally, the data shown in FIG. 4 will be read out as is. As a result, C2
Error detection in the direction is also normal, and the recorded contents of the odd/even parity values match the contents calculated based on the reproduced data at the time of reproduction. Thereby, the reproduction process is terminated, assuming that the reproduced information data is free of errors. On the other hand, as shown in FIG. 5, even if a byte shift occurs during data reproduction and a byte shift of 3 bytes occurs, no abnormality is detected by error detection in the C2 direction. . Therefore, if this continues, incorrect reproduction information data will be adopted. However, based on the value of the information data played here, odd/
The even parity value is calculated and the calculated odd/even parity 52 is used. This odd/even parity 52 and the fourth
Odd/even parity 51 recorded as shown in the figure
A mismatch between odd and even parity codes is detected by comparing them. In this way, it is possible to perform error detection by byte shift, which could not be detected by error detection in the C2 direction and C1 direction of the product code. Description of Information Recording and Reproducing Apparatus (Fig. 1)> Fig. 1 is a block diagram showing a schematic configuration of an information recording and reproducing apparatus according to an embodiment of the present invention. In FIG. 1, 101 is a host computer that outputs an instruction to record data in the information recording/reproducing apparatus of this embodiment or to reproduce data from the information recording/reproducing apparatus. Reference numeral 102 denotes a host interface unit that controls the interface between the host computer 101 and the information recording/reproducing device, and is, for example, a 5C8I. 103 is a CP that controls the entire information recording and reproducing apparatus of the embodiment.
104 is a ROM 104 which stores a control program and various data for the CPU 103 shown in the flowchart of FIG. 2, for example. 105 is a RAM used as a work area for the CPU 103. 106 is a buffer memory, and the host computer 101
The received data is temporarily stored. 10
A disk controller 7 drives a disk device 112 via a disk interface section 111. 108 is an ECC (error detection and correction unit) that detects odd/even parity errors of reproduced data or CI, C
When a 2-parity error is detected, the reproduced data is corrected based on the error code. 109 is an odd/even parity calculation unit that calculates the odd/even parity of the information data when writing the information data to the disk 112, adds the odd/even parity to the information data, and writes the information data to the disk 112. When reproducing data from 112, odd/even parity is calculated based on the read data. Reference numeral 110 denotes an odd/even parity comparison unit which, when reproducing data from the disk 112, uses the odd/even parity code calculated by the odd/even parity calculation unit 109 and the disk device 112 based on the reproduced data. The stored odd/even parity is compared to check whether an error has occurred during reproduction of information data. 111 is the disk device 11
2 and the disk controller 107, such as the ESD I. 112 is a disk drive device. 113 is a disk controller. Next, the operation of reading data from the disk 112 in the information recording/reproducing apparatus of this embodiment based on the above configuration will be explained. Data read from the disk device 112 is stored in the buffer memory 106 via the disk controller 107 and ECCl0B through the disk interface section 111. At this time, if there is an error in the read data, it is detected by the ECClO3 and corrected. However, as shown in FIG. 5, for example, when a byte shift occurs in reproduced data, this cannot be detected. Therefore, odd/even parity calculation unit 1
09, the odd/even parity value of the read data is calculated, and the calculated value is compared with the odd/even parity value reproduced from the disk device 1112 in the odd/even parity comparison unit 110. This allows, for example, the fifth
Even if a byte shift occurs that cannot be detected with C1 and C2 parity as shown in the figure, it can be detected and corrected. Error detection operation of reproduced data (Fig. 2)> Fig. 2 is a flowchart showing the process of reproducing recorded data from the disk 112 in the information recording/reproducing apparatus of this embodiment. remembered. First, when data is read from the disk device 112 in step S1, the odd/even parity calculation unit 109 is instructed to calculate odd/even parity based on the reproduced data in step S2. Then, in step S3, the odd/even parity value calculated by the odd/even parity calculation unit 109 is compared with the odd/even parity value actually read from the disk device 112. If the odd/even parity values of both match, step S4
Then, the reproduced data read from the disk 112 is determined to be error-free and sent to the host computer 101. On the other hand, if these two values do not match in step S3, the process proceeds to step S5, in which it is detected that an error such as a byte shift has occurred, and predetermined error processing is performed in step S6. In this embodiment, the case of detecting an information data error in an information recording/reproducing device has been described, but the present invention is not limited to this, and for example, detecting an error during information transfer in a communication device, an image processing device, etc. At the time of detection, errors in information data can be detected in a similar manner. As described above, according to this embodiment, when recording information data, in addition to adding the parity of the product code, the odd/even parity values of the data are added and recorded. In this way, when this data is reproduced, by comparing the newly calculated odd/even parity value based on the reproduced data with the reproduced odd/even parity value, it is possible to detect, for example, Errors due to byte shifts, etc. can be detected.

【Effect of the invention】

As explained above, according to the present invention, when recording information data, in addition to the parity byte based on the product code, the odd/even parity of this data is calculated and added.
This has the effect of accurately detecting errors in information data during reproduction.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of the information recording and reproducing apparatus of this embodiment. FIG. 2 is a flowchart showing error detection processing when reproducing data from a disc in the information recording and reproducing apparatus of this embodiment. The figure shows the recording direction of information data, product code parities C1 and C2, and odd/even parity data for data when recording on a disc. FIG. 4 is an example of data when recording with the information recording and reproducing apparatus of this embodiment. FIG. 5 is a diagram showing an example of data reproduced with byte shift occurring in the information recording/reproducing apparatus of this embodiment. FIG. 6(A) is a parity error in the C2 direction using a product code. A diagram showing an outline of detection, and FIG. 6(B) is a diagram for explaining a product code. In the figure, 101... host computer, 102...
Host interface section, 103...CPU, 1
04...ROM, 105...RAM, 106...
Buffer memory, 107... disk controller,
108... ECC1109... Odd/even parity calculation unit, 11... Odd/even parity comparison unit, 111
. . . Disk interface section, 112 . . . Disk device. Patent applicant Canon Co., Ltd. agent Patent attorney Yasunori Otsuka (and 1 other person) Figure 2 (A) (B) Figure 2

Claims (1)

[Scope of Claims] Odd/even parity calculation means for calculating odd/even parity codes of the information data based on information data; and odd/even parity codes calculated by the odd/even parity calculation means; , a recording means for adding a parity byte based on a product code to the information data and recording it on a recording medium; and a reading means for reading the information data together with the parity byte and the odd/even parity code from the recording medium. , the odd/even parity calculated by the odd/even parity calculation means based on the information data read by the reading means;
An information recording and reproducing apparatus comprising: a comparing means for comparing an even parity code and an odd/even parity code read by the reading means.