JPH05174505A - Data protective system - Google Patents

Abstract

PURPOSE:To prevent a data from a disc which could not be corrected through a reproduced data error detecting/correcting process (uncorrectable data) from being recognized as a correct data and transmitted to a host unit. CONSTITUTION:A correcting circuit 9 performs error detection and correction for reproduced data in a sector buffer 2 based on syndrome result of the reproduced data added with a first error detection/correction code (Reed-Solomon code or the like). Thus processed data are then fed to an additional error detection circuit 7 where the first error detection/correction code is removed and a second detection code is added for each section. As the second error detection code, a regular parity is provided for errorless sector or corrected sector of the reproduced data whereas a value different from the regular parity (to be decided as an error) is intentionally provided for an uncorrectable sector. The value is detected through a circuit 10 and prevented from being transmitted to a host unit while at the same time the fact is notified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data protection system in an information recording / reproducing apparatus having an error detection / correction function for reproduced data, and more particularly to reliability of reproduced data of an information recording / reproducing apparatus for a computer external storage device. The present invention relates to a data protection method for improving the.

[0002]

2. Description of the Related Art Conventionally, when an error is detected in read data from a disk device, a technique for efficiently recovering the error is disclosed in, for example, Japanese Patent Laid-Open No. 63-90074.
There is a technique described in the publication. In this prior art, the data of each read sector of one track and the read error information are sequentially stored in the buffer, and after the reading of all the sectors of one track is completed, the data in the buffer is dealt with without re-reading if correctable. The recovery processing time is shortened by correcting and recovering the error data of the sector to be read and performing the recovery processing by re-reading only when the data cannot be corrected.

Although the recovery process by re-reading is not described in detail in this prior art, in general, the data of the re-read sector is the first buffer area in which the first read data is stored. Are stored in another second buffer area. When transferring the block including the uncorrectable sector to the host device, after referring to the uncorrectable flag by the microprocessor or the like and transferring the data up to the uncorrectable sector from the first buffer area,
A method is adopted in which re-read data is transferred from the second buffer area, and data after the uncorrectable sector is transferred again from the first buffer area to transfer error-free data.

[0004]

In the above conventional technique, the uncorrectable flag is sent to the microprocessor, and the microprocessor monitors this flag so that when there is an uncorrectable sector, it is not transferred to the host device. The channel is connected and data is transferred to the host device after correct data is obtained for all the sectors in the buffer after re-reading.However, the uncorrectable sector is stored in the buffer and sent to the host device. Therefore, if the uncorrectable flag disappears due to, for example, a circuit failure between the disk device and the microprocessor or a failure of the microprocessor itself, the microprocessor cannot detect the uncorrectable sector.
This uncorrectable sector may be transferred to the host device (usually, the host device cannot identify the uncorrectable sector without sending the uncorrectable flag to the host device). Further, in the above-mentioned conventional technique, there is no means for detecting an error in the data after the error correction processing, and there is a problem that the erroneous data is transferred as the correct data.

Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art and to make it impossible to detect an uncorrectable sector due to a circuit failure or the like, so that the data of the uncorrectable sector is erroneously transferred to the host device. Another object of the present invention is to provide a data protection method for an information recording / reproducing apparatus or the like which has a high data reliability.

In the present invention, the error detection code means a code capable of detecting a data error, and the error detection correction code means a code capable of both detecting and correcting a data error.

[0007]

In order to achieve the above object, the present invention provides a first error detection and correction for a data string (reproduced data string) encoded using a first error detection and correction code. In the data protection system in the information recording / reproducing apparatus in which the second error detection code (B) is added for data protection after the error detection and correction processing is performed by the code (A), this error detection and correction processing result cannot be corrected. One day,
It is characterized in that a means for adding the second error detection code is provided so that the error detection result by the second error detection code is judged to be an error. That is, after the error detection / correction process by the first error detection / correction code, the second error detection code is added to the reproduced data in place of the first error detection / correction code. Is added as a normal error detection code when the reproduction data as a result of the error detection / correction processing is not erroneous or is corrected to correct data, and consciously when the reproduction data as a result of the error detection / correction processing is uncorrectable. Is added as an error detection code indicating that the reproduction data is erroneous. The second error detection code is added, for example, in units of sectors of reproduced data.

Further, according to the present invention, data protection in an information recording / reproducing apparatus or the like for performing error detection / correction processing on a data string (reproduced data string) encoded by using an error detection / correction code by this error detection / correction code. In the method, when the result of the error detection / correction processing is uncorrectable, a means for embedding an uncorrectable flag in the encoded data string may be provided. In this case also, the uncorrectable flag or information corresponding to the uncorrectable flag is added in sector units. This uncorrectable flag information can be used to check the correctness of the data when reading the data from the main buffer. In this case, the error detection / correction code may be added after the correction processing by the error detection / correction code, and the error detection may be performed as necessary.

[0009]

The operation based on the above configuration will be described.

According to the present invention, the first error detection and correction code (A) is applied to the data (sector) or the error-corrected data (sector) whose processing result is determined to be error-free. Is a regular second error detection code (B)
Is added and the second error detection code (B) indicating that the data (sector) is erroneous is intentionally added to the data (sector) whose processing result is uncorrectable. As a result, even when the uncorrectable flag disappears due to a circuit failure or the like, the added second error detection code has the function of the uncorrectable flag and the second error detection code is transferred at the stage of transferring the data to the host device. By checking the error detection code, uncorrectable data can be reliably detected. This makes it possible to cancel the transfer of the uncorrectable data to the higher-level device. Further, even if the uncorrectable data is erroneously transferred to the higher-level device, a recovery process such as re-reading can be achieved by reporting the fact to the higher-level device.

Further, when an error occurs in the data after the correction processing by the first error detecting and correcting code, the error can be detected by the error detecting means using the second error detecting code arranged after that, and the error can be detected by the upper device. The error data transfer can be prevented.

Further, for uncorrectable data (sector),
Even if the uncorrectable flag is replaced with the second error detection code indicating an error, the uncorrectable sector can be surely checked in the same manner.

[0013]

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

FIG. 1 shows a configuration of functional blocks of an optical disk control device according to an embodiment (embodiment 1) of the present invention.
In the figure, 1 is a receiver for receiving reproduction data from a disk reproducing device (not shown), 2 is a sector buffer for storing reproduction data from the receiver 1, and 3 is a sector buffer access for controlling access to the sector buffer 2. The control circuit 4 is a selector for alternately switching the A / B side of the sector buffer and the input / output path to / from the sector buffer, and 5 is the error detection / correction code A added to the reproduced data from the reproduced data received from the receiver 1. A syndrome calculation circuit for generating a syndrome, a correction processing circuit 6 for receiving a syndrome calculation result from the syndrome calculation circuit 5 and performing an error correction process on error data in the sector buffer 2, and a reading circuit 7 for reading from the sector buffer 2 after the correction process. Error detection by the error detection and correction code A for the reproduced data that has been output Means for performing (even if the error correction in the sector buffer data circuit 6, then since there may occur an error in the subsequent path, detecting the error)
And an error detection / addition circuit having means for stopping transfer of the parity part of the error detection / correction code A to the main buffer and means for generating / adding the error detection code B, and 8 is a main buffer for buffering the reproduction data to the host device. , 9
Is a buffer access control circuit for controlling access to the main buffer 8, 10 is an error detection check circuit for performing an error detection check with the detection code B added by the error detection code addition circuit 7 when reproducing data is transferred to a higher-level device, and 11 is A driver for transferring the reproduction data to the host device, and a microprocessor 12 for controlling the operation of each part of the optical disk control device.

Next, the operation of this embodiment will be described.

In the disc reproduction, the data read from the disc reproducing device is added with the parity by the error detection and correction code A at the time of writing to the information data. The information data means data other than parity such as user data. A specific example is shown in FIG. In FIG. 2A, the parity of the 4-byte error detection / correction code A is added to the 35-byte information data, and the total is 585.
Bytes (39 × 15 bytes) form one sector of reproduction data. In this case, if a Reed-Solomon code is used as the error detection / correction code A, an error of up to 2 bytes can be corrected with respect to 39 bytes (information data + parity).

After the reproduced data is received by the receiver 1, it is input to the sector buffer 2 and the syndrome calculation circuit 5. The input to the sector buffer 2 is switched to the A side / B side in units of one sector. Now, assuming that the syndrome result is transferred from the syndrome arithmetic circuit 5 to the correction processing circuit 6 at the time when the reproduction data input to the A side of the sector buffer 2 is completed, the correction processing circuit 6 outputs error data based on the syndrome result. The presence / absence determination is performed, and if an error is detected, the position and pattern of the error are calculated to correct the error data on the A side of the sector buffer 2, and at the same time, information of this correction processing in sector units is reported to the microprocessor 12. .. At this time, the reproduction data from the disk reproducing device is input to the B side of the sector buffer 2.
When the error correction processing is completed, the transfer from the side A of the sector buffer 2 to the main buffer 8 via the error detection addition circuit 7 is started.

While the error detection / addition circuit 7 performs error detection based on the error detection / correction code A, only the information data of the reproduction data shown in FIG. The parity part of is not transferred to the main buffer 8. At the same time, the parity of the error detection code B for the information data is generated. As a result, the output to the main buffer 8 has the configuration shown in FIG. Regarding the parity by the error detection code B shown in FIG. 2B, based on the correction processing result in the correction processing circuit 6, in the case of no error or in the case of a sector in which error correction is performed and correct information data can be recovered. , The parity of the generated error detection code B is added as it is, and in the case of a sector that is uncorrectable and the information data includes an error, a value different from the parity of the generated error detection code B (a value that is as large as possible, For example, an inverted value) is added.
As a result, when a sector that cannot be corrected by the correction processing circuit 5 is input to the error detection check circuit 10, the error detection circuit based on the error detection code B generates a parity and a parity added to the sector end. As a result of comparison, there is a discrepancy and it is determined that the sector contains error data.

An embodiment of the error detection / addition circuit 7 is shown in FIG.

In the figure, 30 is an error detection / correction code A.
Error detection circuit by 31, a transfer control circuit 31 for transferring only the information data section to the main buffer 8, a parity generation circuit 35 for generating a parity by the error detection code B for the output data of the transfer control circuit 31, and 32 an error The detection result of the error detection circuit 30 by the detection correction code A (of the data sent from the sector buffer 2 to the error detection circuit 30)
When an error is detected or the correction result flag in the correction processing circuit 5 is uncorrectable, "FF" is output, and in other cases (when the data on the sector buffer 2 originally has no error, the correction processing circuit "00" in the case where the data in the sector buffer 2 can be corrected by the correction process of 6)
2 is an OR circuit, 33 is an exclusive OR circuit that outputs the exclusive OR of the parity output of the parity generation circuit 35 by the error detection code B and the output of the OR circuit 32, and 34 is as shown in FIG. Is a switching circuit for adding a parity to the end of the information data. The parity output of the parity generation circuit 35 based on the error detection code B is directly output to the switching circuit 34 by the exclusive OR circuit 33, or
It can be output as different values.

The error detection / correction code A in the error detection / addition circuit 7
By performing the error detection of (1), it is possible to detect the reproduction data after the correction processing in the correction processing circuit 6 is erroneous while being input to the error detection adding circuit 7. The error detection / addition circuit 7 does not perform recorrection.

FIG. 4 shows the data storage state of the main buffer 8 when the recovery processing by re-reading is performed on the uncorrectable sector. Reading from sector 1 to sector (N + M) is performed and the start address AD1
Stored from. Since the sector N + 1 cannot be corrected, the re-read data is stored from the address AD5. When transferring a continuous sector block including this uncorrectable sector to the host device, first, the microprocessor 12 recognizes the sector N + 1 as an uncorrectable sector based on the correction processing result information from the correction processing circuit 6, and the buffer access control circuit 9 To the main buffer 8 to the addresses AD1 to AD2, then to the addresses AD5 to AD6, and finally to A
Correct data is transferred by issuing a transfer instruction from D3 to AD4. Since the sector N + 1 from address AD5 to AD6 is recognized as an uncorrectable sector, the transfer from the main buffer 8 to the host device is not performed.

Now, the correction processing circuit 6 and the microprocessor 1
Due to a circuit failure or the like between the two, the processing result of the error correction processing for the reproduced data of the sector buffer 2 by the correction processing circuit 6 is not correctly reported to the microprocessor 12, and therefore the microprocessor 12 causes the error correction processing to be performed. Consider the case where the processing result information of (1) is erroneously recognized (for example, the information that the sector N + 1 is an uncorrectable sector is not transmitted to the microprocessor 12 or the uncorrectable sector information is lost). However, it is assumed that the error detection, the transfer of the detection correction code A, and the addition of the error detection code B performed by the error detection addition circuit 7 are normally operating. In such a case, the microprocessor 1
Since No. 2 issues a transfer instruction from addresses AD1 to AD4, there is a possibility that the uncorrectable data in sector N + 1 will be transferred as correct data. However, in this case, according to the present embodiment, since the error detection check circuit 10 detects an error by the detection code B at the time of transferring the sector N + 1, this information (detection result) is reported to the microprocessor 12, and the microprocessor 12
Reports the occurrence of error data transfer to the host device. Therefore, the microprocessor 12 can instruct the error detection check circuit 10 not to transfer the uncorrectable sector N + 1 of AD2 to AD3 to the host device. Alternatively, even if no means for prohibiting the transfer of the uncorrectable sector from the main buffer 8 to the host device is provided, it is possible to prevent the host device from mistakenly fetching the data of the sector.

Further, according to the present embodiment, the error detection check circuit 10 detects the occurrence of a data error from the output of the error detection addition circuit 7 to the input of the error detection check circuit 10 and determines the data reliability during this period. Has the effect of increasing.

Another embodiment (second embodiment) of the present invention will be described with reference to FIG. This figure is a block diagram showing a configuration in which an uncorrectable flag addition circuit 20 and a correction flag check circuit 21 are added instead of the error detection addition circuit 7 and the error detection check circuit 10 of the block configuration of the embodiment shown in FIG. is there. The data for which the correction processing has been completed is read from the sector buffer 2, and the uncorrectable flag adding circuit 20 sets an uncorrectable flag for recognizing the uncorrectable sector on the basis of the correction processing result of the error correction processing circuit 6 in the sector, for example. Add to the beginning. When transferring from the main buffer 8 to the higher-level device, the uncorrectable flag check circuit 21 checks the presence or absence of this uncorrectable flag. If an uncorrectable sector is detected, it reports to the microprocessor 12 as in the embodiment of FIG. 1, and also reports to the host device that incorrect data was transferred. Also in the present embodiment, when the uncorrectable sector is detected by the uncorrectable flag check circuit, the microprocessor 12 may not send the uncorrectable sector to the host device, or the host device may not correct the uncorrectable sector. May be avoided.

In the embodiment shown in FIG. 1, the error detection correction code A is removed and the error detection code B is added instead, but this error detection is performed even after the error detection correction processing by the error detection correction code A is performed. It is also possible to leave the correction code A added and detect an error in the data generated after this error detection / correction processing by the error detection processing means using the same error detection / correction code A.

[0027]

As described in detail above, according to the present invention,
After the error detection and correction processing by the first error detection and correction code,
When the second error detection code for data protection is added, the second error detection code that is judged to be an error is intentionally added to the uncorrectable data (sector), so that a circuit failure occurs. Even if the information indicating the erroneous data (sector) such as the uncorrectable flag is lost due to
When data is transferred from the buffer containing the uncorrectable data (sector) to the host device, the uncorrectable data (sector) can be checked by using the second error detection code, and as a result, erroneous data is transferred as correct data. There is an effect that it is possible to provide a highly reliable information recording / reproducing apparatus that does not have the problem.

[Brief description of drawings]

FIG. 1 is a functional block diagram of an optical disk control device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of reproduction data and transfer data to a main buffer in FIG.

3 is a block diagram of a configuration example of an error detection addition circuit in FIG.

FIG. 4 is a diagram showing a state in which data is stored in a main buffer in FIG.

FIG. 5 is a functional block diagram of an optical disk control device according to a second embodiment of the present invention.

[Explanation of symbols]

 1 receiver 2 sector buffer 3 sector buffer access control circuit 4 selector 5 syndrome operation circuit 6 correction processing circuit 7 error detection additional circuit 8 main buffer 9 buffer access control circuit 10 error detection check circuit 11 driver 12 microprocessor 20 uncorrectable flag addition circuit 21 uncorrectable flag check circuit 30 error detection circuit with error detection and correction code A 31 transfer control circuit 32 OR circuit 33 exclusive OR circuit 34 parity addition switching circuit

Claims (5)

[Claims] 1. A second error for data protection after performing error detection and correction processing by the first error detection and correction code on a data string encoded using the first error detection and correction code. In the data protection method that adds the detection code,
A means for adding a second error detection code so that when the error detection and correction processing result by the first error detection and correction code is uncorrectable, the error detection result by the second error detection code is judged to be an error. A data protection method characterized by having. 2. A data protection system for performing error detection / correction processing by the error detection / correction code on a data string encoded by using the error detection / correction code. A data protection system comprising means for embedding an uncorrectable flag in the encoded data string when the result is uncorrectable. 3. The second error detection so that when the error detection / correction processing result by the first error detection / correction code is uncorrectable, the error detection result by the second error detection / correction code is judged to be an error. A second error detection code is added so that when the error detection and correction processing result by the first error detection and correction code is not uncorrectable, the error detection result by the second error detection code is determined to be correct. The data protection system according to claim 1, further comprising means for adding 4. An error detection / correction process is performed by leaving the error detection / correction code added to a data string encoded using the error detection / correction code even after performing the error detection / correction process by the error detection / correction code. A data protection system characterized in that an error in data generated later can be detected by an error detection processing means using the same error detection and correction code. 5. A data protection system according to claim 1, which is applied to an information recording / reproducing apparatus.