JP2000268362A - Method for defect detecting and processing of optical disk and recording/reproducing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make recordable a motion video information in real time by moving the position of light beams for every predetermined section, reproducing tracks where information is recorded, detecting a defect from the level of reproduced signals and starting next recording from a position separated a predetermined distance from a position where the defect is detected when a defect is detected. SOLUTION: In recording data on an optical disk, a recording command is transmitted to a CPU 21 via an interface from a significant device as a host, and moreover, the data to be recorded are stored in a buffer memory 28 via an interface circuit 27. When the data stored in the buffer memory 28 reach a predetermined amount, data of a predetermined volume to be recorded are sent to a coding circuit 29 via the interface circuit 27. The coding circuit 29 modulates the input data by a modulation method appropriate to a characteristic of the optical disk and outputs to a laser driver 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect detection method and a recording / reproducing apparatus for recording information on an optical disk for optically recording / reproducing. More specifically, moving image information is transferred in real time by moving the position of the light beam every predetermined period to detect defects, and when a defect is detected, starting the next recording from a position separated by a predetermined amount. The present invention relates to a defect detection processing method and a recording / reproducing apparatus which can record a video signal and reduce disturbance of video during reproduction.

[0002]

2. Description of the Related Art An optical disk is a recording medium on which data is recorded or reproduced optically or magneto-optically, and is suitable for increasing the capacity. The optical disk does not have a closed structure like a hard disk, but can be taken out from a recording / reproducing device. Therefore, even for a defect due to the attachment of dust or the like, encoding processing for error detection and correction and defect management (Defect Management) are performed to guarantee data reliability. Defects that occur on optical discs are roughly classified into two types. One is an initial defect that occurred during the manufacture of an optical disk or the like. The initial defect is detected by a certification performed when formatting the optical disc. The other is secondary defects caused by scratches or foreign matter on the disk surface generated after use. This secondary defect is detected by verification at the time of recording. Small defects are corrected by the error detection and correction coding process, and the recorded data is reproduced without error.However, if the defect is large or the number is large, the reproduced data cannot be corrected and errors will occur. appear. For this reason, when a defect that cannot be corrected is detected, a spare area is reserved for the spare area to perform recording and reproduction.

As such an optical disk, for example, DV
D-RAM disks have been commercialized. FIGS. 6 and 7 show D
1 shows a schematic configuration of a VD-RAM disk. DVD-R
For an AM disc, 2.6 cm on one side of a 12 cm diameter disc
Gbyte information can be recorded. The disk is radially divided into 24 areas (zones). Tracks for recording / reproducing data are formed by uneven grooves, and a land / groove recording / reproducing method for recording / reproducing data on both the irregularities is adopted. The tracks are finely wobbled at a constant period in the radial direction of the disk. By detecting the wobbling, a rotation control of the disk and a timing signal for recording / reproducing are generated. Each track is divided into a plurality of sectors. In the innermost zone 0, one track is divided into 17 sectors, and in the outermost zone 23, it is divided into 40 sectors. An ID portion is provided at the beginning of each sector, and address information indicating the position of the sector on the disk is formed as uneven pits at a position shifted by 1/4 track from the center of the track. 2048 bytes of information can be recorded in one sector. The error detection / correction coding process is performed in units of 32 kbytes (one block), and recording / reproducing is performed with 16 sectors collectively. Whether or not a sector has a defect is determined from an error in the address information and the reproduced data. The list of sectors determined to be defective includes PDL (Prim) for initial defects.
as an area defect list (SDL), and for a secondary defect, a second defect list (SDL).
And recorded on the innermost and outermost circumferences of the disc. The spare area is provided outside the user area of each zone, and when an error occurs, a sector of the spare area in the same zone as the sector in which the error has occurred is used as a replacement sector.

[0004]

By the way, consider the case where the above-mentioned optical disk is used for recording moving image information. In the conventional verify operation at the time of recording, since it is determined based on the presence or absence of an error in data reproduced immediately after recording, it is necessary to perform reproduction in the same time as at the time of recording.
If there is an error as a result of the reproduction, the light beam is moved to the spare area and recording is performed again. The dust on the disk surface has a size of several tens μm or more, and secondary defects occur continuously over a plurality of tracks. For this reason, if dust adheres to the disk surface, recording / reproducing / spare area recording is repeated, which makes it difficult to record the input moving image information in real time.

Accordingly, the present invention has been proposed in view of such a conventional situation, and provides an optical disk defect detection method and recording / reproducing apparatus capable of recording moving picture information in real time without deteriorating reliability. To provide.

[0006]

In order to achieve the above-mentioned object, the present invention focuses on the characteristics of moving image information, and performs a defect detection process by a simple method. In other words, unlike video data, even if video data is distorted due to an error in reproduced data, it does not cause a serious problem such as system stoppage, and video data for a short period of time is unlikely. There is a human visual characteristic of not being bothered. In addition, dust on the disk surface has a size of several tens μm or more, and defects are continuously generated over a plurality of tracks.

Therefore, in the present invention, in the process of detecting a defect at the time of recording moving image information, reproduction is performed while changing the position of the light beam for each predetermined section, and the presence or absence of a defect is determined based on the level of the reproduced signal. In addition to shortening the defect detection time, even if a defect is detected, recording is not performed in the spare area, and the next recording is started from a position separated by a predetermined amount, so that it is continuously performed. It is characterized in that recording is not performed on a defective portion. Further, when the defect is detected, the user is notified of the fact that the defect has been detected, or information such as the position where the defect is detected.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the following examples, and it goes without saying that various conditions can be arbitrarily changed without departing from the gist of the present invention. Here, a DVD-RAM disk is taken as an example,
The present invention is also applicable to other optical discs for optically recording and reproducing information.

A recording / reproducing apparatus and a method of detecting and managing defects according to the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram showing a recording / reproducing apparatus according to the present invention. In FIG. 1, reference numeral 2 denotes an optical head arranged so as to be movable in the radial direction of the optical disk 1, a light emitting element (semiconductor laser) 3 for outputting a light beam of a predetermined power, and detecting reflected light from the optical disk. Light receiving element (photodiode) 4, half mirror 5, collimator lens 6, objective lens 7, and actuator for controlling the focus and track position of the light beam by driving the objective lens in a direction perpendicular to the disk surface and in a radial direction. Eight. The recording / reproducing surface of the optical disc 1 is spirally formed with track grooves formed of lands and grooves alternately in the radial direction. Here, the projection 1a is called a groove and the recess 1b is called a land as viewed from the light beam. The light beam emitted from the light emitting element 3 of the optical head 2 is applied to the groove 1a or the land 1b on the optical disk 1 via the half mirror 5, the collimator lens 6, and the objective lens 7. The reflected light from the optical disk 1 passes through the objective lens 7, the collimator lens 6, and the half mirror 5 again and is incident on the light receiving element 4. The light receiving element 4 is divided into a plurality of light receiving portions (for example, divided into four), and each light receiving signal is output to the signal generation circuit 9. In the signal generation circuit 9, a focus error signal (FE) a indicating a deviation of the focus of the light beam irradiated on the optical disk 1 based on these light receiving signals, and a tracking error signal (FE) indicating a deviation of the light beam from the track center. TE) b and a signal (SUM) c indicating the total amount of reflected light from the disk are generated.
The ID gate generation circuit 10 generates an ID gate signal d indicating the timing of the ID portion from the tracking error signal c of the ID portion formed by pits formed by a ト ラ ッ ク track from the center of the track. Then, the address information of each sector is reproduced. In the ID part, focus and tracking error signals a and b are formed by uneven pits.
Sample and hold (S / H) 12, 1
Three circuits are provided to hold the error signal immediately before the ID section based on the ID gate signal d. Focus servo loop is sample and hold (S / H) circuit 1
2. It is composed of a phase compensation amplifier 14 and a focus driver 15. The focus driver 8 drives the focus actuator 8 a based on the focus error signal a from the signal generation circuit 9, so that the focus actuator 8 a Servo control is performed so that the light beam is focused. Further, a tracking servo loop is constituted by a sample / hold (S / H) 13 circuit, a polarity inversion circuit 16, a phase compensation amplifier 17, an addition circuit 18 and a tracking driver 19, and a tracking error signal b from the signal generation circuit 9 is formed. The servo control is performed so that the light beam follows the track by driving the tracking actuator 8b by the tracking driver 19 based on the above. The jump pulse generation circuit 20 generates a jump signal based on a jump trigger signal e from the CPU 21 for controlling the entire apparatus, and drives the tracking actuator 8b via the addition circuit 18 and the tracking driver 19, so that the light beam is made adjacent. A track jump operation for forcibly moving to a track is performed. The polarity inversion circuit 16 switches the polarity of the tracking error signal b so that the light beam follows the groove 1a or the land 1b by the land / groove switching signal f from the CPU 21. Since tracks on the optical disk 1 are wobbled minutely in the radial direction of the disk with a constant period, the tracking error signal b includes a signal corresponding to the wobble. The wobble signal detection circuit 22 detects the wobble component g from the tracking error signal b by a filter or the like, and is converted by the binarization circuit 23 into a wobble pulse signal h corresponding to the wobble. The wobble pulse signal h is input to the spindle control circuit 24, and detects a deviation between the frequency of the reproduced wobble signal g and a predetermined frequency as a spindle error signal. The rotation of the spindle motor 26 is controlled by the spindle driver 25 based on the spindle error signal, so that the optical disc 1 rotates at a predetermined speed.

Next, a procedure for recording moving image information using the above-described recording / reproducing apparatus will be described. Prior to recording moving image information on a new disk, management information for managing data by a format operation is initialized and the information is recorded. Here, it is assumed that an initial defect is dealt with by detecting a defect after recording, and certification is not performed. When recording data on the optical disc, a recording command is transferred from the host device as a host to the CPU 21 via the interface circuit 27, and the data to be recorded is stored in the buffer memory 28 via the interface circuit 27. . When the data stored in the buffer memory 28 reaches a predetermined amount, data of a predetermined capacity to be recorded is sent to the encoding circuit 29 via the interface circuit 27. The encoding circuit 29 modulates the input data by a modulation method suitable for the characteristics of the optical disk, and outputs the modulated data to the laser driver 30. The laser driver 30 drives the light emitting element 3 based on the input signal and modulates the intensity of the light beam, thereby recording on the optical disc 1.

A defect detection operation for confirming whether data is correctly recorded on the optical disk 1 after recording will be described.
This will be described with reference to FIGS.

FIG. 2 corresponds to a case where there is no defect, and shows a case where recording is performed from time t0 to t1 (sectors S0 to Se). In order to detect a defect after recording, the light beam is moved to a sector before the recording start position S0 at time t2 by means such as track jump or the like, and defect detection is started from time t3 when the light beam reaches S0. At a time point t4 when a predetermined sector period is detected, the light beam is moved to an adjacent track by the track jump means. Thereafter, similarly, at time t5 when defect detection is performed for a predetermined number of sectors,
At t6, the track is moved to an adjacent track by a track jump, and a defect is detected up to the recording end sector Se. Here, it is assumed that jumping is performed at a position shifted with respect to the radial direction of the disc so that a defect spreading in the radial direction is not erroneously detected. If no defect is detected during the period (t3 to t7) from the start to the end of the verification, the next recording is started from the sector next to the last sector Se of the previous recording.

Next, the operation when there is a defect will be described with reference to FIG.
This will be described with reference to FIG. Even when there is a defect, recording is performed on the optical disk in the same manner as when there is no defect. At the time t2, the light beam is moved to a sector before the recording start position S0 at a time t2 by means such as a track jump to detect a defect after the recording is completed, and the defect detection is started at a time t3 when the light beam reaches the S0. At a time point t4 when a predetermined sector period is detected, the light beam is moved to an adjacent track by the track jump means. Thereafter, similarly, at times t5 and t5 when defect detection is performed for a predetermined number of sectors.
At 7, the track is moved to an adjacent track by a track jump, and a defect is detected up to the recording end sector Se. Time t
In step 6, a defect is detected, and the position (address) of the track or sector where the defect is detected is stored in the memory 31 of the CPU 21. A display device 32 connected to the CPU 21 for notifying the user that a defect has been detected.
Display on. For example, as shown in FIG. 4, a warning of the occurrence of a defect and information on a position (a zone, a track, a sector, or the like) where the defect has occurred, and preferably an approximate position on the disk are displayed. This allows the user to easily confirm the position where dust is attached and remove the dust. Also, for example, a mode for checking a disk is provided, and the user performs this check mode after removing dust, thereby performing defect detection again on a sector or track previously registered as a defect, and when there is no defect, It becomes possible to perform a process of deleting the registration of a defect and enabling recording. If a defect is detected during the period from the start to the end of the defect detection (t3 to t7), the light beam is moved to the outer periphery by a predetermined number of tracks at the time t7 when the defect detection is completed. The next moving image information is recorded from the first sector of the track after the movement. Here, dust on the disk surface is several tens of μm
With the above size, the track interval (pitch) is 1μ
m, so the number of tracks moving to the outer circumference is 1
It is desirable that the number of tracks be about 0 to 100 tracks.
Or you may make it move to the zone following the zone in which the defect was detected. This makes it possible to move the next recording position to a track having no defect and to avoid recording continuously on a track having a defect. When all the moving image information from the host is recorded, information such as the position of the sector where the moving image information is recorded is recorded, and the CP
The information of the sector or track where the defect is detected stored in the memory 31 of U21 is added to the defect list and recorded in the defect management area of the optical disk 1.

In the above embodiment, since a defect is detected by reproducing only a part of the recorded signal while performing a track jump, the defect can be detected in a short time.
The transfer speed of the moving image information sent from the host is set to Drh (Mb
it / sec), the transfer speed of data to be recorded on the optical disk is Drd (Mbit / sec), and the time Tin required for video data sent from the host to be stored in the buffer memory by a predetermined amount Mb (Mbit) is

[0016]

(Equation 1)

Is given by On the other hand, the buffer memory 28
To record data stored in the optical disk on the optical disk Twr
Is

[0018]

(Equation 2)

## EQU1 ## Assuming that the time Tvr of the defect detection operation for confirming whether the information has been correctly recorded is to record moving image information on the optical disc 1 in real time

[0020]

(Equation 3)

It is necessary to In the conventional defect detection method by the verify operation, all the recorded data are reproduced,
Since the defect is determined based on the presence or absence of an error in the reproduced data, it takes time to detect the defect as much as recorded (Twr = Tvr). Therefore,

[0022]

(Equation 4)

The transfer speed of data from the host is
It is necessary to record at twice or more transfer speed. Further, when there is a defect, the data is recorded in the spare area. In order to record the moving image information in real time, it is necessary to record the data at a transfer speed three times or more the transfer speed of the data from the host. In contrast, in the defect detection method of the present invention, a defect is detected by reproducing only a part of the recorded signal. For example, if the defect detection is performed by thinning out one track at a time, the time required for the defect detection is reduced. In half the time required. Also, even if a defect is detected, recording to the spare area is not performed.

[0024]

(Equation 5)

Thus, it is sufficient to record at a transfer speed of about 1.5 times the transfer speed of the moving picture information from the host. Further, if the defect detection is performed by thinning out two or more tracks, the recording transfer speed can be further reduced with respect to the transfer speed of the moving image information from the host. Therefore, it is possible to perform recording in real time while detecting defects even if the transfer speed for recording on the optical disk is low. However, if the number of tracks to be thinned out increases, defect detection may be missed. Therefore, it is necessary to perform defect detection at intervals sufficiently shorter than a defect of several tens of μm. Further, after recording the moving image information stored in the buffer memory 28 and performing defect detection, the time required until a predetermined amount of moving image information is stored in the buffer memory 28 again is given by Tin− (Twr + Tvr). During this period, recording and defect detection need not be performed. Therefore, during this period, it is possible to reduce the power consumption by stopping the operation of the blocks other than the interface circuit 27, the buffer memory 28, and the like, and the time until a predetermined amount of moving image information is stored in the buffer memory 28 The time required for recording and defect detection (Tw
The effect becomes larger as (r + Tvr) is shorter.

Next, a method of detecting a defect will be described with reference to FIG. FIG. 5 shows the waveform of each part at the time of detecting a defect for tracks N and N + 1. When performing defect detection, focus and tracking control is performed so that a light beam follows a track on which defect detection is performed. If the optical disc 1 has a defect, the focus and tracking error signals a and b are greatly disturbed. Therefore, the respective error signals are input to the comparators 33 and 34, and when the error signals a and b exceed a predetermined level, Indicates that the outputs i and j of the comparators 33 and 34 are defective.
21. Here, since the error signal is disturbed in the ID portion, the error signals input to the comparators 33 and 34 are the signals n and o in which the S / H circuits 12 and 13 suppress the error signal in the ID portion. Further, at a defective portion due to dust adhering to the disk surface, the level of the reflected light from the optical disk 1 is reduced, so that the level of the total light amount signal c is reduced.
Therefore, the total light amount signal c is detected by the envelope detection circuit 35.
When the envelope signal k falls below a predetermined level by the comparator 36,
Assuming that there is a defect, the output p of the comparator 36 is set to C
Input to PU21. Further, in the defective portion, the tracking error signal b is disturbed, and the wobbling component generated from the tracking error signal b cannot be detected, so that the wobble pulse signal h is missing. When the wobble pulse signal h is lost for a predetermined period or more, the wobble loss detection circuit 37 determines that there is a defect and inputs the wobble loss detection signal m to the CPU 21.

In the sectors M and M + 1 of the track N, since there is no defect, no large disturbance occurs in the focus and tracking error signals a and b, and the level of the total light amount signal c does not decrease.
No signal indicating a defect is output from 34 and 36. Further, since no loss occurs in the wobbling pulse signal h, no signal indicating a defect is output from the wobble loss detection circuit 37. A track jump is used to change a track for defect detection. In the track jump, the jump pulse from the jump pulse generation circuit 20 is added to the addition circuit 1 by the jump trigger signal e from the CPU 21.
8 and the signal q is added to the tracking driver 19.
The light beam is moved to an adjacent track by driving the tracking actuator 8b. Here, since the track N + 1 is a groove while the track N is a land, the polarity of the tracking error signal b is switched by a land / groove switching signal f from the CPU 21. At the time of the track jump, the level of the tracking error signal b increases because the light beam crosses the track, and the comparator 34 detects the signal j indicating the detection of a defect.
In addition, when the light beam crosses the track, a wobbling pulse signal is also missing, and a signal m indicating a defect is output from the wobble missing detection circuit. Therefore, CPU
Does not use the defect detection result at the time of the track jump operation. In the sector M + 3 of the track N + 1, a large disturbance occurs in the focus and tracking error signals a and b due to the defect, and the level of the total light amount signal c also decreases. Therefore, the comparators 33, 34, and 36 output signals i, j, and p indicating a defect. In addition, the wobbling pulse signal h is also missing, and the wobble missing detection circuit 37 outputs a signal m indicating a defect. In the CPU 21, the signals i, j, p, m from the comparators 33, 34, 36 and the wobble loss detection circuit 37 are output.
The presence or absence of a defect is determined from the correlation of the above. If the time and frequency of the defect exceed a predetermined value, it is determined that an error occurs in the reproduced data which cannot be corrected by the error correction processing, and the sector or the sector where the defect is detected is determined. Track position (address) CP
It is registered in the memory 31 of U21. At the time when all the moving image information from the host is recorded, information such as the position of the sector where the moving image information is recorded is recorded, and the information of the sector or track where the defect is detected stored in the memory 31 of the CPU 21 is stored in a defect list. In addition, the information is recorded in a defect management area of the optical disc 1.

On the other hand, when reproducing the data recorded on the optical disk 1, the interface circuit 2
A reproduction request is made to the CPU 21 via the. CPU2
In step 1, the light beam is moved to a track on which information requested by the host is recorded by means such as track jump. From the signal generation circuit 9, the total light amount signal c which is a reproduction signal from the target track is input to the reproduction signal detection circuit 38, and a binarized signal is generated. The binarized signal is subjected to decoding and error correction processing by a decoding circuit 39, and outputs data reproduced from the optical disc 1 to a host via an interface circuit 27.

In the above embodiment, the output i of the comparator 33 for detecting the level of the focus error signal, the output j of the comparator 34 for detecting the level of the tracking error signal, the output p of the comparator 36 for detecting the level of the envelope signal, Although the presence or absence of a defect is determined from the correlation of the output m of the wobble loss detection circuit 37, the determination may be made using any of these signals. In addition, the defect is detected after the recording. However, even if the defect is detected by the signals i, j, and m from the comparators 33 and 34 and the wobble loss detection circuit 37 during the recording, the recording is interrupted and the light is stopped. The next recording may be performed by moving the beam to a position separated by a predetermined distance.

[0030]

As is clear from the above description, according to the present invention, the time required for defect detection can be shortened, so that moving image information can be recorded in real time. In addition, when a defect is detected, the next recording is started from a position separated by a predetermined amount, so that it is possible to prevent continuous recording on a defective portion, and the image at the time of reproduction can be prevented. Can be reduced. In addition, by notifying the user of the warning of the occurrence of the defect and the position where the defect has occurred, the user can easily perform the process of confirming the position where dust is attached and removing the dust.

[Brief description of the drawings]

FIG. 1 is a block diagram of a recording / reproducing apparatus according to the present invention.

FIG. 2 is a diagram illustrating a trajectory of a light beam when a defect is detected when the optical disk has no defect.

FIG. 3 is a diagram illustrating a trajectory of a light beam when a defect is detected when the optical disk has no defect.

FIG. 4 is a diagram illustrating an example of a display of a display circuit when a defect is detected.

FIG. 5 is a diagram showing waveforms at various points when a defect is detected.

FIG. 6 is a diagram showing a structure of a DVD-RAM disk.

FIG. 7 is a diagram showing a structure near an ID portion of a DVD-RAM disk.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Optical head, 3 ... Light emitting element, 4 ... Light receiving element, 7 ... Objective lens, 8 ... Actuator, 9 ... Signal generation circuit, 21 ... CPU, 32 ... Display circuit, 37 ... Wobble missing detection circuit.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G11B 20/18 572 G11B 20/18 572C 572F 574 574G H04N 5/85 H04N 5/85 D 17/06 17/06 F term (Reference) 5C052 AA02 BB02 DD09 5C061 BB01 CC07 5D044 BC04 CC04 DE62 DE96 5D090 AA01 BB04 CC01 CC05 CC18 DD03 DD05 EE02 FF02 FF05 FF38 GG03 GG07 HH01 HH08 JJ03 LL04 5D118 AA13 CD03 CA03

Claims (5)

[Claims] 1. A defect detection method for a disk-shaped information recording / reproducing medium for recording information by condensing a light beam on a track formed in advance with concave and convex grooves and reproducing the recorded information. The position of the light beam is moved to the position, and the track on which the information is recorded is reproduced while performing focus and tracking control, and the defect is detected from the level of the reproduced signal. A defect detection processing method characterized in that the next recording is performed from a position separated by a predetermined amount. 2. A processing method for detecting a defect according to claim 1,
A defect detection processing method, wherein a light beam is moved at a position that is not aligned in a radial direction. 3. A disc-shaped information recording / reproducing medium having tracks formed in advance with uneven grooves is irradiated with a light beam, and a reproduction signal, a focus error signal, and a tracking error signal are generated from reflected light from the recording medium. In a recording and reproducing apparatus for recording information while performing focus and tracking control based on the focus and tracking error signals, and reproducing the recorded information from a reproduction signal, the position of a light beam is moved every predetermined interval, A defect detecting means for detecting a defect in the recording medium by reproducing the track on which is recorded while performing focus and tracking control, and comparing the reproduced signal or the focus error signal or the tracking error signal with a predetermined level; When a defect is detected by the defect means, it is separated by a predetermined amount Recording and reproducing apparatus being characterized in that from the position to perform the next recording. 4. The recording / reproducing apparatus according to claim 3, wherein the light beam is moved at a position which is not aligned in the radial direction. 5. A recording / reproducing apparatus according to claim 3, further comprising: display means for displaying information, wherein said display means displays a defect occurrence on said recording medium and a defect occurrence position based on an output of said defect detection means. An information recording / reproducing apparatus characterized in that the information recording / reproducing apparatus is displayed.