JPH09237447A - Device and method for inspecting disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of inspecting a disk recording medium for performing high density recording by switching the equalizing characteristic of the equalizing means of a high frequency signal to one different from that at the time of data recording when data is reproduced. SOLUTION: An optical magnetic disk recording/reproducing device 15 supplies a reproducing frequency signal S1 to an equalizer circuit 32 and generates a reproducing high frequency signal S4 equalized by an equalizing characteristic according to a reproducing mode. The device 15 supplies the signal S4 to a comparator 33, this signal is compared with a reference voltage Vth and a compared output signal S5 is supplied to a PLL circuit 34. The device 15 generates a reading clock clocked with the signal S5 and reproducing data S2 synchronized with this. When an error correcting circuit 18 cannot restore the data S2 to original data S3, the device 15 supplies data S6 from the circuit 18 to a control circuit 16 and this data is stored as a defective sector. The device 15 supplies a switch control signal S7 from the circuit 16 for each mode, switches the high frequency gain of the equalizer circuit 32 and sets an equalizing characteristic according to each mode.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. TECHNICAL FIELD OF THE INVENTION Conventional Technology Problems to be Solved by the Invention (FIGS. 7 to 9) Means for Solving the Problems (FIG. 2) Embodiments of the Invention (FIGS. 1 to 8)

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk inspecting apparatus and a disk inspecting method, which can be applied to, for example, recording / reproducing on / from a magneto-optical disk by a magneto-optical disk recording / reproducing apparatus.

[0003]

2. Description of the Related Art Conventionally, a magneto-optical disk used in a general magneto-optical disk recording / reproducing apparatus cannot correctly read address data formed in advance as a pit due to a physical defect generated during manufacturing. There is a defective area that cannot be correctly reproduced even if data is recorded in the user recording area. Therefore, after manufacturing, the magneto-optical disk is checked for address data over the entire area, and test data is recorded and reproduced in the user recording area for verification.

At this time, in the magneto-optical disk, the track number and sector number of the defective area are recorded in a specific area on the magneto-optical disk. When the user actually records / reproduces data, the magneto-optical disc recording / reproducing apparatus reads the data recorded in a specific area on the magneto-optical disc, and performs recording / reproducing while avoiding a defective sector. As a result, the magneto-optical disk recording / reproducing apparatus operates as if no data error apparently occurred and prevents the occurrence of data error,
Improves data reliability.

Incidentally, the causes of defects occurring in the magneto-optical disk during manufacturing are stamper defects, defects generated during injection molding and 2P process of substrate manufacturing, spatters and coating defects of recording materials and protective film agents, and substrate defects. Defects due to poor refractive index, deterioration of the substrate and recording material, scratches generated during manufacturing, dust trapped in the double-sided bonded substrate, etc. are considered.

In order to surely detect defects of various kinds of these recording media immediately after manufacturing and register a defective sector, the recording / reproducing conditions at the time of verification immediately after manufacturing are the worst conditions for actual use by the user. It is set in consideration. For example, generally, the laser power at the time of recording or reproducing is shifted from the optimum point. Further, the ECC (code correction circuit) of the data detection unit
The correction capability is set lower than the usage level of the user. Further, the equalization characteristic of the high frequency circuit of the address detection unit is shifted from the optimum point to a certain value. By setting in this way, it is determined whether or not the address data and the data in the user recording area can be correctly reproduced.

[0007]

However, in recent years, as the size of the recording pit is reduced to improve the recording density (recording linear density), relative defects such as fine defects and scratches on the magneto-optical disk are relatively increased. The influence has increased compared to the past. That is,
In the magneto-optical disk having a high recording density, it is difficult to control the waveform abnormality of the high frequency signal of the address data due to the disk defect in the manufacturing process.

On the other hand, the recording / reproducing apparatus has a spatial frequency transfer characteristic of the reproducing optical system (hereinafter referred to as MTF (modulation transfer).
function)), and the unevenness of the equalization characteristics of the high frequency circuit is not reduced to the extent that the recording density is increased. Further, there is a difference in characteristics between the verification device and the recording / reproducing device that uses the verified magneto-optical disk. For this reason, when only the conventional detection conditions are applied, there occurs a phenomenon in which the address data can be read correctly or cannot be read due to a device difference, and it is becoming difficult to accurately determine the quality of the address data.

For example, the MTF of the optical head is not uniform because the eclipse rate changes due to uneven divergence angles of the laser diodes used. The eclipse rate is represented by A / W, where A is the diameter of the objective lens of the optical head and W is the effective diameter of the laser beam.

FIG. 7 shows the MTF curve 1 with poor characteristics in the high frequency range by (A / W) = 1, where (A / W) = 1, and (A / W) =
2, the MTF curve 2 having good high frequency characteristics is shown by a solid line. MT near the shortest wavelength in the former MTF curve 1
The F value becomes the A value. On the other hand, the latter MTF value in the vicinity of the shortest wavelength in the MTF curve 2 is a B value higher than the A value. A higher spatial frequency is desired as the recording density is increased. Therefore, the difference between the A value and the B value increases in the region of the shortest wavelength or longer.

As for the equalization characteristic, the characteristic in the high frequency region becomes important as the recording density is increased. That is, as shown in FIG. 8, as the MTF irregularity of the optical head relatively increases, the equalization characteristics are required to have a wide gain correction range in a high frequency range. Incidentally, in FIG. 8, the equalization characteristic curve 3 when the gain in the high frequency range is large is shown by a solid line, and the equalization characteristic curve 4 when the gain in the high frequency range is small is shown by a broken line. As the recording density is increased, the influence of the equalization characteristic adjustment error increases, and the overall characteristic difference between the optical head and the high frequency system also increases.

Due to the difference in the characteristics of each device due to these causes, the reproduced waveform of the address data obtained from the address portion precoded on the magneto-optical disk has a threshold value Vth.
There is a possibility that a defective portion that is difficult to detect by the comparator may be generated due to insufficient level change with respect to. For this reason,
The defect detection results for the reproduced waveform of the address data are not uniform.

For example, as shown in FIG. 9 (A), for a reproduced waveform 5 obtained from a certain pit sequence with a normal address part,
Consider the reproduced waveform 6 in which the level of the central portion is lowered due to the lack of the central portion of the pit sequence. In this case, playback waveform 6
If the level in the central part of does not drop to the threshold value Vth,
The comparator outputs the comparison output signal having the comparison waveform 7 that rises for the same period as when the reproduction waveform 5 is compared, and cannot detect a defect due to missing of a pit or the like.

On the other hand, as shown in FIG.
When the gain of the MTF in the high frequency range is high and the gain of the equalization characteristic in the high frequency range is high, the reproduction waveform 6 is emphasized in the high frequency range.
As a result, the reproduced waveform 6 becomes the reproduced waveform 8 in which the level lowering portion is emphasized. Accordingly, the comparator can detect a defect due to missing of a pit or the like by outputting a comparison output signal having the comparison waveform 9 in which the level reduction is detected at the level reduction portion of the reproduction waveform 8.

Next, as shown in FIG. 9 (C), with respect to the reproduced waveform 10 obtained from a certain short pit sequence of the address part, the level of the top part of the regenerated waveform 10 is reduced due to the lack of the top pit of this pit sequence. Consider the lowered playback waveform 11. In this case, the level and phase of the head portion of the reproduced waveform 11 are affected by the lack of pits, so that the comparator has a shorter rising period than when the reproduced waveform 10 is compared. A comparison output signal with 12 must be output.

However, the equalization level has conventionally been fixed at a certain value. Therefore, when the gain in the high frequency region of the equalization characteristic is set only to a high value, the reproduced waveform 11 is corrected to the reproduced waveform 13 having a large rising and falling angle as shown in FIG. 9D. It Therefore, the comparator may output the comparison output signal having the comparison waveform 14 detected as if there is no defect.

In another recording / reproducing apparatus using the verified magneto-optical disk, when the gain in the high frequency region of the equalization level is low, the reproduced waveform 6 shown in FIG. It is read as the reproduced waveform 5 when there is no missing of a bit. On the other hand, the reproduction waveform 11 shown in FIG. 9C is not read as the comparison output signal having the comparison waveform 12 having a short period.

In this way, it is possible to accurately judge whether or not arbitrary data recorded on the magneto-optical disk for high density recording has been correctly reproduced under the conventional detection conditions due to the difference in the equalization level for each device. It has become difficult to detect bad sectors. For this reason, simply registering a defective sector detected by the conventional method may cause a defect omission in which the address data cannot be correctly read from the verified magneto-optical disk, or a state in which the recorded sector data cannot be read. I got it. Therefore, there has been a problem that it has become difficult to sufficiently secure the reliability for the defect management of the verified magneto-optical disk.

In order to solve this, the magneto-optical disk is verified a plurality of times to ensure the certainty of the detection result, and the verification device set to the upper limit of the deviation of the equalization level for each device and the verification set to the lower limit. It is conceivable that the verification will be performed for each device. However, verifying a plurality of times has a drawback of increasing manufacturing time. In addition, making the upper and lower limit specifications of the deviation of the equalization level for each device greatly increases the cost of the verification device and increases the manufacturing time, which makes the verification complicated and increases the cost. There was a flaw.

The present invention has been made in view of the above points, and is intended to propose a disk inspection apparatus and a disk inspection method capable of improving the reliability of inspection of a disk-shaped recording medium for recording at high density. is there.

[0021]

In order to solve such a problem, according to the present invention, in a disk inspection device for inspecting a disk-shaped recording medium to determine a defect position, a high frequency signal to be recorded / reproduced on / from the disk-shaped recording medium is used. When converting
Equalization means having first and second equalization characteristics different from each other, data error correction means for correcting an error in reproduced data obtained based on a high frequency signal reproduced from a disk-shaped recording medium and equalized, etc. And control means for controlling the activating means. Further, the control unit switches the first and second equalization characteristics to determine the defect position based on the correction result of the data error correction unit.

Further, according to the present invention, in a disk inspection device for inspecting a disk-shaped recording medium to determine a defect position, the first and the second different from each other when equalizing a high frequency signal to be recorded / reproduced on / from the disk-shaped recording medium. The equalizing means having the equalizing characteristic 2 and the high-frequency signal reproduced from the disk-shaped recording medium and equalized are input, and the waveform distortion detecting means for detecting the waveform distortion of the high-frequency signal and the equalizing means are controlled. And a control means. In addition, the control unit switches the first and second equalization characteristics to determine the defect position based on the detection result of the waveform distortion detection unit.

When the data is reproduced, the equalization characteristic of the high-frequency signal equalization means 19 is switched to an equalization characteristic different from that when the inspection data is recorded, so that it is difficult to reliably detect the disk-like recording in the past. The level change of the waveform distortion portion due to the defect position on the medium is emphasized, and this defect position can be detected with higher accuracy. As a result, the reliability of the inspection of the disk-shaped recording medium for high density recording can be further improved.

Further, according to the present invention, in a disk inspection method for inspecting a disk-shaped recording medium to determine a defect position, a first equalization characteristic when a high frequency signal corresponding to recording data is recorded on the disk-shaped recording medium. To a second equalization characteristic different from the above, and equalization processing for equalizing the high frequency signal reproduced from the disk-shaped recording medium by the second equalization characteristic, and reproduction data obtained based on the equalized high frequency signal. A data error correction process for correcting an error and a defect position determination process for determining a defect position based on the correction result of the data error correction process are provided.

Further, according to the present invention, in a disk inspection method for inspecting a disk-shaped recording medium to determine a defect position, a first equalization characteristic when recording a high frequency signal corresponding to recording data on the disk-shaped recording medium. Equalization processing for switching the second equalization characteristic different from the above to equalize the high frequency signal reproduced from the disk-shaped recording medium by the second equalization characteristic, and the waveform distortion for detecting the waveform distortion of the equalized high frequency signal. A detection process and a defect position determination process for determining a defect position based on the detection result of the waveform distortion detection process are provided.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a magneto-optical disk recording / reproducing apparatus 15 as a disk inspecting apparatus as a whole, and when verifying a magneto-optical disk, in addition to detecting a defective sector as a defect position under conventional detection conditions. , Equalization characteristics are switched, recording and reproduction are performed, and waveform distortion of the reproduction high-frequency signal S1 is detected to detect defective sectors.

The magneto-optical disk recording / reproducing apparatus 15 is internally controlled by a system control circuit 16 as a control means. The magneto-optical disk recording / reproducing device 15 is a SCSI (Small Computer System) which is an interface circuit.
Interface) Inputs / outputs data to / from an external device via the controller 17.

When recording data, the magneto-optical disk recording / reproducing device 15 gives the data to the error correction circuit 18 as the data error correction means and adds the error correction code to the data, which is a high frequency signal (indicated by RF in the figure). ) Supply to circuit 19. The magneto-optical disk recording / reproducing device 15 provides the equalization characteristic according to the recording mode to the equalization circuit 32 as the equalization means in the high frequency signal circuit 19 by switching by the system control circuit 16.

The magneto-optical disk recording / reproducing device 15 efficiently records data on the magneto-optical disk 20 as a disk-shaped recording medium, so that the data matched with the characteristics of the recording / reproducing system is transferred from the high frequency signal circuit 19 to the laser power control circuit. Give to 21. The magneto-optical disk recording / reproducing device 15 applies a drive signal from the laser power control circuit 21 to the optical head fixing section 22 to drive the laser diode 23 in the optical head fixing section 22 to record on the magneto-optical disk 20. At this time, the magneto-optical disc recording / reproducing device 15 drives the laser diode 23 by feeding back the intensity data of the laser light obtained through the optical head fixing portion 22 and the high frequency signal circuit 19 to the laser power control circuit 21.

Next, when reproducing data, the magneto-optical disk recording / reproducing device 15 gives the reproduction high frequency signal S1 output from the optical head fixing section 22 to the high frequency signal circuit 19. At this time, the magneto-optical disk recording / reproducing device 15 gives the equalizing characteristic according to the reproducing mode to the equalizing circuit 32 in the high frequency signal circuit 19 by switching by the system control circuit 16.

In the magneto-optical disk recording / reproducing apparatus 15, the high frequency signal circuit 19 generates the reproduction data S2 based on the reproduction high frequency signal S1 and supplies the reproduction data S2 to the error correction circuit 18. The magneto-optical disk recording / reproducing device 15 is
The error correction circuit 18 corrects an error in the data based on the reproduced data S2 to restore the original data S3.
3 is output to the outside via the SCSI controller 17.

The optical head fixing portion 22 is used for the magneto-optical disk 2
The light obtained from 0 is transmitted to the photodetector 2 via the optical head movable part 24.
5, and the output signal of the photodetector 25 is amplified by the preamplifier 26. As a result, the servo and high frequency signals are amplified. Further, the optical head fixing section 22 drives the laser diode 23 by superposing the drive signal and the high frequency signal at the time of recording by the high frequency superposition circuit 27.

The magneto-optical disk recording / reproducing apparatus 15 controls the actuator of the lens included in the optical head movable portion 24 by the focus servo circuit 28 to focus on the magneto-optical disk 20 and the track on the magneto-optical disk 20. Is scanned by the tracking servo circuit 29. In the magneto-optical disk recording / reproducing device 15, the rotation of the magneto-optical disk 20 is controlled by a disk servo circuit 30 as a driving means, and the entire position of the optical head movable part 24 is controlled by a radial servo circuit 31 in the radial direction of the magneto-optical disk 20. Control to scan the track on the disk 20.

Next, when verifying the recording area of the magneto-optical disk 20, the magneto-optical disk recording / reproducing apparatus 15 can correctly reproduce the data with respect to the recorded signal within the set error correction capability. Whether or not it is possible, and the number of signals recorded multiple times in the address part is set (for example, 2 out of 3).
It is detected and stored for each sector whether or not it can read more than one piece. Further, the magneto-optical disc recording / reproducing device 15 detects and stores the presence or absence of the reproduced waveform distortion of the address data.

Further, the magneto-optical disk recording / reproducing device 15
Detects whether or not the servo error signal reaches a certain value or more and whether or not the reproduction synchronizing signal of the data portion can be detected under a certain number of matching conditions. Further, the magneto-optical disk recording / reproducing device 15 detects whether or not the reproduced high frequency signal is missing.

The magneto-optical disk recording / reproducing device 15 judges a defective sector based on the above detection result and stores it in the system control circuit 16. The magneto-optical disc recording / reproducing apparatus 15 uses the defect management area (DMA) on the magneto-optical disc 20 based on the position information of the defective sector found during the verification.
(Detect Nanagenment Area)) is recorded in a specific area, and when actually used, recording and reproduction are performed while avoiding defective sectors. Incidentally, when determining these defective sectors, the laser power and the recording and reproducing conditions may be intentionally deviated from the normal use conditions, or the ECC correction capability may be set low.

FIG. 2 shows the main part of the defective sector detection system of the magneto-optical disk recording / reproducing apparatus 15. The magneto-optical disk recording / reproducing apparatus 15 supplies the reproduction high frequency signal S1 given from the optical head fixing section 22 to the equalization circuit 32 in the high frequency signal circuit 19 and equalizes it according to the equalization characteristic according to the reproduction mode. A reproduction high frequency signal S4 is generated. The magneto-optical disk recording / reproducing device 15 supplies the reproduction high frequency signal S4 to the comparator 33, compares it with the reference voltage Vth, and compares the comparison output signal S5 obtained by PLL (Phase Locked Loop).
It is given to the circuit 34.

The magneto-optical disk recording / reproducing device 15 is a PL
In the L circuit 34, the comparison output signal S5 is locked to generate the read clock and the reproduction data S2 synchronized with the read clock. When the error correction circuit 18 cannot restore the reproduction data S2 to the original data S3, the magneto-optical disk recording / reproducing device 15 gives the error flag data S6 as a correction result to the system control circuit 16 from the error correction circuit 18 to provide a defective sector. Memorize as.

In the magneto-optical disk recording / reproducing apparatus 15, the system control circuit 16 supplies a switching control signal S7 for each of the erasing, recording and reproducing modes to switch the gain of the equalizing circuit 32 in the high frequency range. The equalization characteristic corresponding to is set. For example, in the case of the above three modes, the magneto-optical disk recording / reproducing device 15 sets the high frequency region gain low in the erasing and recording modes, and sets the high frequency region gain high in the reproducing mode to judge the quality of the address data. Incidentally, the combination of the mode and the equalization gain may be opposite, or the high frequency gain may be set high in the two modes.

When the high frequency band gain of the equalization characteristic of the reproduction mode is set high, the waveform distortion of the reproduction waveform 6 shown in FIG. 9A is a defect like the reproduction waveform 8 shown in FIG. 9B. The level change due to is emphasized. When the high frequency band gain of the equalization characteristic of the reproduction mode is set low, the waveform distortion of the type of the reproduction waveform 13 shown in FIG. 9D has a defect like the reproduction waveform 11 shown in FIG. 9C. The level change due to the part is emphasized.

As a result, the magneto-optical disk recording / reproducing apparatus 15 obtains the comparative output signal S5 whose waveform is surely distorted,
In the error correction circuit 18, an address data defect can be detected by an error detection redundancy code check (hereinafter referred to as CRC (Cyclic Redundancy Check)) signal. Therefore, the magneto-optical disk recording / reproducing apparatus 15 can improve the accuracy of defect detection due to pit defects or the like.

On the other hand, as shown in FIG. 3, the reproduced waveform 35 in which the voltage level of the distortion part slightly exceeds the reference voltage Vth even when the equalization characteristic is switched is judged by the error correction circuit 18 to have no error. It In order to avoid this, the magneto-optical disk recording / reproducing apparatus 15 determines the reproduced high frequency signal S4 of the reproduced waveform 35 by the waveform distortion detecting circuit 36 in the high frequency signal circuit 19 as the waveform distortion detecting means.

That is, the magneto-optical disk recording / reproducing apparatus 1
Reference numeral 5 supplies the reproduced high frequency signal S4 to the waveform distortion detection circuit 36, and detects the presence or absence of waveform distortion of the reproduced high frequency signal S4 by the reference voltage Vth1 which is higher than the reference voltage Vth and the reference voltage Vth2 which is lower than the reference voltage Vth. When the waveform distortion of the reproduction high frequency signal S4 is detected, the magneto-optical disk recording / reproducing device 15 gives the distortion detection signal S8 as a detection result to the system control circuit 16 to store it as a defective sector.

As shown in FIG. 4, the waveform distortion detection circuit 36
Inputs the reproduced high frequency signal S4 to the two comparators 37 and 38, respectively. In addition, the waveform distortion detection circuit 36
Applies the reference voltage Vth1 to the comparator 37 and the reference voltage Vth2 to the comparator 38. Incidentally, the waveform distortion detection circuit 36 includes resistors R _H1 , R _H2 , R _L1 and R _L2.
Constant voltages V1 and V2 are applied to both ends of the series circuit consisting of, and the reference voltage Vth is applied to the middle point of connection of the resistors R _H2 and R _L1.
Is applied. As a result, the waveform distortion detection circuit 36
Obtains the reference voltage Vth1 from the connection midpoint of the resistors R _H1 and R _H2 , and obtains the reference voltage Vth2 from the connection midpoint of the resistors R _L1 and R _L2 .

The waveform distortion detection circuit 36 includes a comparator 3
The output signals S9 and S10 of 7 and 38 are given to the exclusive OR circuit 39 to compare the levels of the output signals S9 and S10. As a result, as shown in FIG. 3, in the waveform distortion detection circuit 36, the level of the output signal S9 is the reproduction high frequency signal S4.
When it falls to the logic "L" level due to the waveform distortion of, the exclusive OR circuit 39 outputs the distortion detection signal S8 which rises to the logic "H" level to the system control circuit 16. Therefore, the system control circuit 16 can detect that waveform distortion has occurred in the reproduced high frequency signal S4 and register it as an address error.

FIG. 5 shows a magneto-optical disk recording / reproducing device 15
An example of a recording format of a magneto-optical disk according to FIG. A spiral recording track is provided on the magneto-optical disk 20. The recording track is divided into, for example, 3102-byte sectors for each recording area of a certain amount of recording data. A precoded address area of, for example, 55 bytes is provided at the head of each sector.
Address information necessary for accessing data is recorded in advance in the address portion.

The address information includes a sector mark, a reference signal, an address mark signal, an identification signal and a postamble signal (in the figure, SM, VFO, AM, ID and P, respectively).
(Indicated by A). The reference signal VFO, the address mark signal AM, and the identification signal ID are recorded three times to ensure reliability. Sector mark SM
Indicates the start of the address part. Reference signal V
The FO causes the PLL circuit to create the clock required for signal detection. The address mark signal AM is an identification signal ID
Indicates the beginning of. The identification signal ID is composed of a track number and a sector number, an identification number indicating what number the identification signal ID is, and a CRC signal. The postamble signal PA indicates the end of the address part.

The magneto-optical disk recording / reproducing device 15 discriminates and accesses each sector by the track number and the sector number, and judges by the CRC signal whether or not the reproduced track number and sector number are correct.

A description will be given of a case where the magneto-optical disk having the above-mentioned structure is bulk-erased by another device and then the magneto-optical disk is verified. Incidentally, the bulk erasing method is generally adopted because it can be erased almost instantaneously, unlike the method of erasing by a verification device.

In the verification recording operation, the magneto-optical disc recording / reproducing apparatus 15 verifies the address data while recording the verification reference signal in the user recording area. When verifying the address data, the magneto-optical disk recording / reproducing apparatus 15 sets the high frequency region gain to a low value as shown by the equalization characteristic curve 4 in FIG.

The first judgment condition of the quality of the address data is a case where there is one or more address data which cannot be correctly read out of the three address data in one sector and all three address data cannot be read. Further, the second determination condition of the quality of the address data is a case where an error is detected by the waveform distortion detection. When at least one of the first and second determination conditions is satisfied, the magneto-optical disk recording / reproducing device 15 determines this sector as defective and stores it.

Under this judgment condition, for example, FIG.
Consider a reproduced waveform 40 having a distorted portion at the center of the original reproduced waveform 5 in the address data shown in FIG. In the distorted part, the frequency components are biased in the high frequency range. However, the high frequency gain of the equalization characteristic is set low during recording. Therefore, the voltage level of the distorted portion is the reference voltage Vth.
If it does not drop, the reproduced waveform 40 is read as normal address data.

The waveform distortion detection circuit 36 also determines that the reproduced waveform 40 has no waveform distortion when the voltage level of the distortion section does not drop below the reference voltage Vth1. Therefore, with only the equalization characteristic set at the time of recording, the sector that outputs the reproduced waveform 40 is regarded as a waveform defective sector and DMA is performed.
I can't register to, and the detection omission occurs.

Next, in the verification reproducing operation, the magneto-optical disk recording / reproducing apparatus 15 sets the high frequency band gain to a high value as shown by the equalization characteristic curve 3 in FIG. This allows
As shown in FIG. 6D, the reproduced waveform 40 changes to a reproduced waveform 41 in which the voltage level of the distortion portion at the center of the waveform is lower than that of the reproduced waveform 40. In the reproduced waveform 41, the voltage level of the distortion portion at the center of the waveform does not drop to the reference voltage Vth. Therefore, the magneto-optical disk recording / reproducing device 15 cannot detect the address error in the error correction circuit 18.

However, when the voltage level of the distortion portion at the center of the reproduced waveform 41 falls below the reference voltage Vth1, the magneto-optical disk recording / reproducing device 15 causes the waveform distortion detection circuit 36 to detect the center of the waveform. Detect the distorted part. As a result, the magneto-optical disc recording / reproducing apparatus 15 can determine the address data having the reproduced waveform 41 as a defective address and register it as a defective sector in the system control circuit 16.

In this way, the magneto-optical disc recording / reproducing apparatus 15 switches the high frequency region gain of the equalization characteristic between the recording operation and the reproducing operation and detects the waveform distortion. As a result, the magneto-optical disk recording / reproducing device 15
Can detect the defective sector caused by a micro defect of the magneto-optical disk or the like with higher accuracy and improve the reliability of the address data.

According to the above configuration, when the verification data is reproduced, the equalization characteristic of the equalization circuit 32 in the high frequency circuit 19 is switched to an equalization characteristic different from that when the verification data is recorded, and the reproduced high frequency signal S4. By detecting the waveform distortion of, the level change of the waveform distortion part due to the defect of the address part on the magneto-optical disk, which was difficult to detect reliably in the past, is emphasized, and the defect of the address part is detected with higher accuracy. can do. As a result, it is possible to further improve the reliability of verification of the magneto-optical disk recorded at high density.

Further, by changing the mode during the verification, it is possible to secure sufficient reliability with one verification operation. As a result, it is possible to suppress an increase in manufacturing cost.

In the above embodiment, the case of verifying the magneto-optical disk 20 has been described, but the present invention is not limited to this, and is widely applied to an inspection device for verifying a disk-shaped recording medium recorded by an arbitrary recording method. Applicable. In this case, the same effect as described above can be obtained.

Further, in the above-mentioned embodiment, the case of verifying the address data is described, but the present invention is not limited to this, and can be applied to the case of verifying the data recorded in the user recording area. it can.

[0062]

As described above, according to the present invention, when the data is reproduced, the equalization characteristic of the equalization means for the high frequency signal is switched to the equalization characteristic different from that when the data is recorded. The level change of the waveform distortion portion due to the defect position on the disk-shaped recording medium, which is difficult to detect, is emphasized, and this defect position can be detected with higher accuracy. As a result, it is possible to realize a disk inspection device and a disk inspection method that can further improve the reliability of the inspection of a disk-shaped recording medium that records at high density.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a magneto-optical disk recording / reproducing apparatus by a disk inspection apparatus and a disk inspection method according to the present invention.

FIG. 2 is a block diagram showing a defective sector detection system of the magneto-optical disk recording / reproducing apparatus of FIG.

FIG. 3 is a waveform diagram for explaining a distortion detection state based on a plurality of threshold values.

FIG. 4 is a connection diagram showing a configuration of a waveform distortion detection circuit.

FIG. 5 is a schematic diagram showing an example of a recording format on a disk.

FIG. 6 is a waveform diagram showing a waveform change and a distortion detection signal due to a difference in equalization characteristic.

FIG. 7 is a characteristic curve diagram showing MTF for each eclipse rate.

FIG. 8 is a characteristic curve diagram showing two types of equalization characteristics having different gains in a high frequency range.

FIG. 9 is a waveform diagram showing a waveform change and a distortion detection signal due to a difference in equalization characteristic.

[Explanation of symbols]

1, 2 ... MTF curve, 3, 4 ... Equalization characteristic curve, 5,
6, 8, 10, 11, 13, 35, 40, 41 ... Reproduction waveform, 7, 9, 12, 14 ... Comparison waveform, 15 ... Magneto-optical disk recording / reproducing device, 16 ... System control circuit, 17 ... SCSI controller, 18 ... error correction circuit, 19 ... high-frequency signal circuit, 20 ... magneto-optical disk, 21 ... laser power control circuit, 22
...... Optical head fixed part, 23 ...... Laser diode, 24
...... Optical head movable part, 25 ...... Photo detector, 26 ...... Preamplifier, 27 …… High frequency superposition circuit, 28 …… Focus servo circuit, 29 …… Tracking servo circuit, 30 ・ ・ ・
… Disk servo circuit, 31 …… Radial servo circuit,
32 ... Equalization circuit, 33, 37, 38 ... Comparator, 34 ... PLL circuit, 36 ... Waveform distortion detection circuit,
39 ... Exclusive OR circuit.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location G11B 20/18 572 G11B 20/18 572F

Claims (10)

[Claims] 1. A disk inspecting apparatus for inspecting a disk-shaped recording medium to determine a defect position, the first and the second being different from each other when equalizing a high frequency signal to be recorded / reproduced on / from the disk-shaped recording medium. Equalizing means having equalizing characteristics, data error correcting means for correcting an error in reproduced data obtained based on the equalized high frequency signal reproduced from the disk-shaped recording medium, and controlling the equalizing means. A disk inspecting device, comprising a control means, and switching the first and second equalization characteristics to determine the defect position based on a correction result of the data error correction means. 2. The equalized high frequency signal is input, and a waveform distortion detection means for detecting the waveform distortion of the high frequency signal is provided, and the correction result of the data error correction means and the detection of the waveform distortion detection means. The disk inspection apparatus according to claim 1, wherein the defect position is determined based on the result. 3. The disk inspection apparatus according to claim 1, wherein the first and second equalization characteristics have different gains in a high frequency range. 4. A disk inspecting apparatus for inspecting a disk-shaped recording medium to determine a defect position, the first and the second being different from each other when equalizing a high frequency signal to be recorded and reproduced on the disk-shaped recording medium. An equalizing means having equalizing characteristics, a waveform distortion detecting means for receiving the equalized high frequency signal reproduced from the disk-shaped recording medium and detecting a waveform distortion of the high frequency signal, and controlling the equalizing means. A disk inspecting device, comprising: a control means, and switching the first and second equalization characteristics to determine the defect position based on a detection result of the waveform distortion detection means. 5. The disk inspection apparatus according to claim 4, wherein the first and second equalization characteristics have different gains in a high frequency range. 6. A disk inspecting method for inspecting a disk-shaped recording medium to determine a defect position, wherein a first equalization characteristic different from a first equalization characteristic when a high frequency signal corresponding to recording data is recorded on the disk-shaped recording medium. Equalization processing for switching the equalization characteristic of No. 2 to equalize the high frequency signal reproduced from the disk-shaped recording medium with the second equalization characteristic, and reproduction data obtained based on the equalized high frequency signal. A data error correction process for correcting the above error and a defect position determination process for determining the defect position based on the correction result of the data error correction process. 7. A waveform distortion detection process for detecting a waveform distortion of the equalized high frequency signal, wherein the defect position determination process includes a correction result of the data error correction process and a detection result of the waveform distortion detection process. 7. The disk inspection method according to claim 6, wherein the defect position is determined based on 8. The disk inspection method according to claim 6, wherein the first and second equalization characteristics have different gains in a high frequency range. 9. A disk inspecting method for inspecting a disk-shaped recording medium to determine a defect position, wherein a high-frequency signal corresponding to recording data is different from the first equalization characteristic when recording on the disk-shaped recording medium. Equalization processing for switching the equalization characteristic of 2 to equalize the high frequency signal reproduced from the disk-shaped recording medium by the second equalization characteristic, and a waveform for detecting waveform distortion of the equalized high frequency signal. A disk inspection method comprising: distortion detection processing; and defect position determination processing for determining the defect position based on the detection result of the waveform distortion detection processing. 10. The disk inspection method according to claim 9, wherein the first and second equalization characteristics have different gains in a high frequency range.