JPS6344374A - Defect detecting device for optical disk - Google Patents

Abstract

PURPOSE:To detect having the possibility that data cannot be corrected and to improve the reliability of the data by outputting a defect detecting signal when a data writing signal is not outputted for a prescribed time or above in a data area. CONSTITUTION:A defect detecting device 1 monitors a data writing detecting signal 3 outputted from an optical disk drive 2, when the signal 3 is not outputted for a prescribed time or above in a data area, a defect detecting signal 4 is generated. When the signal 4 is inputted, when an optical disk control device 5 inputs a reading signal 6 from the disk drive 2 and checks the data, the device controls so as to change a defective sector to other sector. Thus, the sector including the defect having the possibility that the error to be unable to be detected by the error correcting function of the device 5 cannot be corrected is changed by the error correcting function of the device 5 regardless of whether or not correction can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention: 1. Field of the Invention The present invention relates to an optical disc defect detection device that can detect defects that may make error correction impossible, and can improve data reliability.

[Problems to be solved by conventional techniques and inventions] In recent years,
Optical disk devices that write/read information using semiconductor lasers have been put into practical use. Generally, the optical disk device is used by being connected to a computer, but an interface (hereinafter referred to as an optical disk control device) between the optical disk device and the computer is usually required. This optical disk control device has a general-purpose interface such as 5C8I or GP-IB on the computer side, and an interface specific to that device on the optical disk device side, and controls access to the optical disk by commands from the computer.

On the other hand, an optical disc on which information is written is composed of a plurality of recording tracks, and one track is composed of a plurality of sectors. Each sector is preformatted with an address (hereinafter referred to as IQ) for identification. The optical disk control device is configured to read this ID, confirm that it is the sector to be accessed, and perform writing/reading.

By the way, in the optical disc, usually, due to the characteristics of the medium,
It is impossible to eliminate defects and the error rate is 1o-
The limit is about 6. Therefore, for example, in order to use it for secondary storage for a computer, an error correction function is required. However, this error correction function has a limit, and it is not possible to correct errors for large defects, so a process is usually performed in which a block with such a large defect is replaced with another block. Conventionally, for rewritable media such as magnetic disks, a method was used to perform an out-of-date test in advance, check where defective blocks were located on each medium, and then prevent the defective blocks from being used. has been adopted. However, with optical discs on which information can only be written once, it is not possible to perform the writing test described above, so conventionally, (
1) Detecting defects by checking before writing. (2
) Check by reading after fortune telling. After identifying a defective block and attaching a mark indicating that the block is a defective block, the defective block is replaced with another block.

On the other hand, although it is said that the optical disc can guarantee data storage for 10 years, for example, no confirmation has been obtained. In general, optical recording uses methods such as drilling holes in the medium (creating bits) and changing the phase of the medium (for example, from crystal to amorphous), which causes the medium to deteriorate over time and increase defects. It has also been reported that.

To deal with this, for example, Japanese Unexamined Patent Application Publication No. 59-116937 discloses a check method using the above-mentioned reading after writing.
When performing a rewrite, a check is performed using a lower correction ability and higher rewriting criteria than the normal error correction ability.
A technique has been disclosed that detects defects exceeding a certain level and can prevent data recorded on an optical disk from becoming unplayable due to an increase in defects over time.

However, in the prior art example, (1) the configuration of the error correction circuit becomes complicated; (2) It may take time to determine whether the error can be corrected. There are other problems.

[Objective of the Invention] The present invention has been made in view of the above circumstances, and has a simple configuration that can detect defects that may make error correction impossible, and improves the reliability of data recorded on optical discs. It is an object of the present invention to provide an optical disc defect detection device that can improve the performance of optical disks.

[Means and effects for solving the problem] As shown in the conceptual diagram of FIG. At the time of reading to check whether or not data has been written, the data write detection signal 3 that detects data writing output from the optical disk drive 2 is monitored, and the data write detection signal 3 is detected within the data area.
A defect detection signal 4 is generated when the defect detection signal 4 is not output for a predetermined period of time or more.

Therefore, it is possible to detect defects that cannot be detected by the error correction function of the optical disk type tII device and may become impossible to correct.

Then, for example, the read signal 6 from the optical disk drive 2 is input to the optical disk controller @ 5 that controls writing of data to the optical disk and reading of data from the optical disk, and it is checked whether the data has been written correctly. When the defect detection signal 4 is input during reading, the defective sector is controlled to be replaced with another sector.

As a result, sectors containing defects that cannot be detected by the error correction function of the optical disk control device 5 and that may become uncorrectable, regardless of whether or not they can be corrected by the error correction function of the optical disk control device 5. be replaced.

Therefore, even if defects increase to some extent due to deterioration of the medium after data is written, errors may become uncorrectable.
Data reliability is increased.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

Figures 2 to 7 relate to one embodiment of the present invention, with Figure 2 being a block diagram of a defect detection device, and Figure 3 being an explanation showing the sector format of an optical disk and signals input to the defect detection device. 4 is a waveform diagram showing the operation of the defect detection device,
FIG. 5 is a flowchart showing the processing at the time of reading by the optical disk control device, and FIG. 6 is a flowchart showing the processing by the optical disk control device when a defect detection signal is generated.
FIG. 7 is a flowchart showing the sector replacement process of the optical disk control 2Il device.

As shown in FIG. 2, the defect detection device 1 of this embodiment has a data write detection signal 3, a clock signal 7 output for each byte when data is written to each sector of the optical disk, and 10 copies of the sector. A signal that distinguishes the data part (
8 (low level when it is the 10th part, high level when it is the data part), and a signal 9 indicating that a sector is being read are input, and the data write detection signal 3 is maintained for a predetermined period of time, in this example, 2 bytes. Minute time (-2,6μs)
If no more output is made, a defect detection signal 4 is generated.

Incidentally, the sectors of the optical disk used in this embodiment are configured as shown in FIG. That is, one sector consists of a sector mark 18 indicating a division between sectors, an ID section 19 in which track addresses and sector addresses are preformatted, a data section 21 in which data is written, and a gap before this data section 21. It consists of (1) (preamble) 20 and a gap (2) (postamble) 22 after the data section 21 .

In this embodiment, the gap (1) 20, the data section 21
, the lengths of the gaps (2) 22 are 35 bytes, 581 bytes, and 14 bytes, respectively, and the gaps (1) 20 before and after the data section 21 are
, the length of the data area 23 including the gap (2) 22 is 630 bytes.

As shown in FIG. 3(a), the signal 8 is at low level at the sector mark 18 and one ID section, and at the gap (1) 20.
This is a signal that becomes high level in the data section 21 and gap (2) 22. Further, the signal 9 is a signal that is cleared at the rising edge of the signal 8 and set at the beginning of the sector mark 18, as shown in FIG. 3(b).

Further, the data write detection signal 3 is output from both the ID section 19 and the data area 23, and is output with a delay of about 4 bytes. The data write detection signal 3 is at a low level when there is no defect in the medium and data is normally written, but when there is a defect in the medium, it becomes a high level at the position of the defect.

The signal 8 is delayed by, for example, 10 bytes by a delay circuit 11, and is connected to a preset terminal PR of a down counter 10 and a D-type flip-flop (hereinafter abbreviated as FF).

) 12 clock terminals.

The down counter 10 receives the signal 8 from the delay circuit 11.
An initial value, for example 620, is preset by the signal delayed by 10 bytes, and the clock signal 7 is counted down by 620 times.

Further, the FF is set by a signal obtained by delaying the signal 8 by 10 bytes by the delay circuit 11, and is cleared by the carry output of the down counter 10.

On the other hand, the male penetration detection signal 3 is input to the trigger input terminal of the one-shot multivibrator 13. This one-shot multivibrator 13 is triggered by the rising edge of the write detection signal 3,
For example, a 2.6 μs pulse corresponding to 2 bytes of data is generated.

The output page of the one-shot multivibrator 13 is D
input to the clock terminal of type FF14, and this FF
The data write detection signal 3 is inputted to the input end of 14.

Then, when the output port of the one-shot multivibrator 13 rises, the data write detection signal 3
If the data write detection signal 3 is at a high level for 2.6 μs corresponding to 2 bytes of data, the FF 14 is triggered. The output Q of this FF 14 is input to the clear terminal CLR of this FF 14 via an inverter 15, and when this FFI 4 is triggered, a pulse-like output h? I
It is designed to output .

The output of the FF 12], the output image of the FF 14, and the signal 9 are input to an AND gate 16 of negative logic. The output signal of this AND gate 16 is input to a timing generation section 17, and this timing generation section 17 latches the output signal of the AND gate 16,
The defect detection signal 4 is output as the signal 8 of the next sector rises.

Next, referring to FIG. 4, the operation of the defect detection station 1 of this embodiment will be explained.

The down counter 10 is preset by a signal obtained by delaying the signal 8 shown in (a) by 10 bytes (-13 μs) by the delay circuit 11, and at the same time, the FF 12 is set. This FF 12 is set until it is cleared by the key 11 of the down counter 10. Therefore, as shown in (b), the output signal of F'12 becomes low level 10 bytes after the separation between ID section 19 and data area 23, and becomes high level after 620 bytes.

As shown in (C), the data write detection signal 3 is at a low level when there is no defect in the medium and the data is correctly written in, and when there is a defect in the medium, it becomes high level at the position of the defect. It's a signal.

Note that this data write detection signal 3 is transmitted between the IO section 19 and the data area 23 or between the data area 2 even in cases other than defects.
The unrecorded portion between the sector mark 3 and the sector mark 18 also becomes high level. The one-shot multivibrator 13 is triggered by the rise of this data write detection signal 3, and the one-shot multivibrator 13 operates as shown in (d).
A 2.6 μs pulse (output image) corresponding to 2 bytes of data is generated as shown in FIG. If the data writing detection signal 3 is at a high level when the output of the one-shot multivibrator 13 rises, that is, the data writing detection signal @3 is high for 2.6 μs corresponding to 2 bytes of data. If it is at the level, it is assumed that there is a defect and the FF 14 is triggered. And this F
F14 outputs a pulse-like signal (output and output) as shown in (e).

By the way, as mentioned above, the data write detection signal 3 becomes high level even in unrecorded areas other than defects,
In accordance with this, the FF 14 outputs a pulse-like signal (output image) even in areas other than defects. However, the FF
As mentioned above, the output image of I2 becomes low level just 10 bytes from the separation between the 10th part 19 and the data area 23, and becomes high level after 620 bytes, so there are no defects in the data area 23 except for the unrecorded part. This is a gate signal that enables only detection. Therefore, the output image of the FF 12, the output of the FF 14, and the output signal of the AND gate 16 to which the signal 9 shown in (f) is input are active (high level) only at the defective part, as shown in (Q). ). The output signal from this AND gate 16 is transmitted anywhere in the data area 23 within one sector by 2 bytes (-2,
If there is a defect of 6 μs or more, it is output.

The output signal of the AND gate 16 is latched by a timing generator 17. Then, this timing generator 1
7 is (h
), a defect detection signal 4 is generated.

In order for the optical disk control device 5 to know the address of the sector in which a defect has been detected, it must know the sector address when reading of the ID section 19 of the next sector is completed, and when the defect detection signal 4 is input. All you have to do is move this sector address back one.゛In other words, if the read sector address is other than 0, 1 is read from that sector address.
If the address is 0, it is the IAn sector address.

Next, the optical disc system '60' when reading to check whether the data has been written correctly! The operation of ill 5 will be explained with reference to FIG.

The optical disk υ1tllll device 5 inputs the read signal 6 from the optical disk drive 2, and checks whether there is an error that cannot be corrected when reading of the target sector is completed. If there is an error that cannot be corrected, a replacement flag is set for that sector.

This replacement flag is a flag corresponding to each sector. The above processing is performed for all sectors within one track.

During the processing shown in FIG. 5, a defect detection signal 4 is generated from the defect detection device 1, and if this defect detection signal 4 is interrupted by the optical disk control device 5, as shown in FIG. The sector address at the time when the defect detection signal 4 interrupt occurs is read, and 1 of the sector address is read.
Set the replacement flag in the previous sector.

On the other hand, sector replacement processing is performed as shown in FIG. That is, the replacement flag is checked for each sector, and if the replacement flag is set, a replacement mark is set in that sector, and the data written in this sector is rewritten in the replacement sector.

Through the above-described processing, the optical disk control device 5 can correct errors when errors cannot be corrected or when there is a defect of 2 bytes (-2.6 μs) or more in the data area of one sector.
The sector will be replaced.

In this way, according to the present embodiment, sectors containing defects that may become uncorrectable are replaced regardless of whether or not they can be corrected by the error correction function of the optical disc tII device 5. After data is written, even if defects increase to some extent due to deterioration of the medium, errors will not become uncorrectable, and the reliability of the data will be improved.

Note that the present invention is not limited to the above embodiments, and various circuit configurations are possible. Further, the size and length of the defect that generates the defect detection signal can be set arbitrarily.

[Effects of the Invention] As explained above, according to the present invention, defects that may become uncorrectable can be detected with a simple configuration, and the reliability of data recorded on an optical disc can be improved. It has the effect of being able to.

[Brief explanation of drawings]

Figure 1 is a conceptual diagram of the present invention, Figures 2 to 7 relate to an embodiment of the present invention, Figure 2 is a configuration diagram of a defect detection device, and Figure 3 is a sector format and defect detection of an optical disk. FIG. 4 is a waveform diagram showing the operation of the defect detection device, FIG. 5 is a flowchart showing the read processing of the optical disk control device, and FIG. 6 is a diagram showing how the defect detection signal is input to the device. FIG. 7 is a flowchart showing the process of the optical disk control device when this occurs. FIG. 7 is a flowchart showing the sector replacement process of the optical disk control device. 1... Defect detection device 3... Data write detection signal 4... Defect detection signal 5... Optical disk control device Fig. 1 Fig. 2 Fig. 7a3 Fig. 4 Fig. 5

Claims (1)

[Claims] After writing data to an optical disk, during reading to check whether or not this data has been written correctly, a signal that detects data writing from the optical disk is monitored, and a signal that detects the data writing within the data area. What is claimed is: 1. A defect detection device for an optical disc, comprising: a defect detection means for determining whether or not a period of time during which no signal is output is longer than a predetermined time, and generating a defect detection signal in accordance with this determination.