JPH10188282A - Disk device and its verifying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance precision in verification. SOLUTION: A regenerative signal Sa of a WORM(wire once read many times type) disk is supplied to a binarization circuit 33 through a filter part 32 to be binarized by a slice level Ls, and the regenerative data Da are obtained. The filter part 32 performs waveform equalization processing and high band boost processing. A detector 34 obtains a central level, that is, the slice level Ls from the upper/lower envelope signal of the regenerative signal of a VFO3 (variable frequency oscillator) of a data part. At a verifying time checking whether or not the data written in the WORM disk are read out correctly, the filter part 32 is controlled, and a high band boost amount is enlarged than usually. Thus, the amplitude of the regenerative signal of the VFO3 becomes large, and the level Ls is changed so that an error rate when the data written in the state of low recording power are read out is deteriorated. It becomes possible to be decided as NG at the verifying time even for the write-in of the data that the recording power is low, and the read-out of the data becomes impossible according to a time lapse.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk device suitable for application to, for example, a write-once disk device and a verification method thereof. Specifically, at the time of verifying whether data written on a disk medium can be read correctly, a disk device that attempts to increase the accuracy of verification by increasing the amount of boost in the high frequency range of a reproduction signal more than usual. This relates to the verification method.

[0002]

2. Description of the Related Art If a recording surface of a disk medium such as an optical disk or a magneto-optical disk has a large or a large number of defects,
Even when data is written by adding a redundant word ECC (Error Correction Code), error correction cannot be performed, and data may not be read correctly. For this purpose, a process of checking whether data written on the disk medium can be read correctly is performed. This process is called verification. At the time of this verification, if the data cannot be read correctly, a process for writing the data to another area (alternate area) is performed.

[0003]

By the way, for example, WORM (Write Once Read M
In any type) disc, when data is written (mark edge recording) with a lower recording power, marks such as holes recorded after several hours to about 40 hours have deteriorated, and immediately after writing, There is a possibility that correctly read data may become unreadable.

FIG. 7 shows the relationship between recording power, asymmetry and error rate in a WORM disk. The recording power is low and the asymmetry is, for example, −3.
In the area AR of 0% to -10%, as described above, the data that can be read correctly immediately after writing is several hours to 4 hours.
After a lapse of about 0 hours, there is a possibility that the error rate becomes high and reading becomes impossible. In FIG.
A solid line a indicates asymmetry, a solid line b1 indicates an error rate immediately after writing, and a broken line b2 indicates an error rate after a lapse of several hours to about 40 hours.

The reason why the error rate becomes so high that reading becomes impossible is considered as follows.
That is, for example, in the case of the hole drilling method, when data is written with a lower recording power, the periphery of the hole formed in the WORM disk remains in a phase change state, and this portion is changed to the original state with time. It is considered that the mark length is shortened.

FIG. 8 shows that user data is 1024 bytes / byte.
It shows the sector format of a 130 mm WORM disk that is a sector. This sector format includes a 63-byte header section, an 18-byte flag section,
It consists of a 309-byte data part and a 20-byte buffer.

The header section is an area indicating a physical block address of each sector on the disk.
It is preformatted in advance by pits on the substrate. The flag section is an area for writing a flag indicating the state of data in the sector. The data section is an area for writing user data. The buffer is an area for a disk rotation fluctuation margin, and is provided so that data and addresses do not overlap even if a shift occurs due to rotation jitter or the like during recording.

[0008] The header portion starts from a leading pattern called a SM (Sector Mark) and has a VFO (Variable Frequency O) that gives the rotation phase of the disk that is actually rotating.
scillator) and A giving the start position of the address data
M (Address Mark) and ID (Identifer) containing a track number and a sector number as identification signals
Is repeated twice, and ends with PA (Postamble).

Here, the same identification signal is repeatedly written in each of the _two IDs (ID ₁ and ID ₂ ).
Each ID has a track number and a sector number identification signal, and a CRC (Cyc
lic Redundancy Check) code.

In the flag section, in addition to FLAG indicating that writing has been performed, ALPC (Automatic Laser Pos) which is a test section for adjusting the laser power level.
werControl).

The data section includes a VFO (Variable Frequency Oscillat) which is a continuous data pattern for PLL lock.
or), and SY which is a synchronization signal of the data part
In addition to the area for writing NC, there is a data field as an area for writing user data and the like.
In the data field, in addition to the user data, when a sector to be originally written is a defect, a process for writing in a replacement sector, that is, a control byte for performing a so-called defect process, and an ECC (Error Correction Cod) which is a redundant word for error correction.
e) CRC (Cyclic Redundancy) for error detection
Check) code, R which is a special code pattern for synchronization
Esync is written.

The above-described asymmetry corresponds to the WO shown in FIG.
VFO of sector format data part of RM disk
And the envelope of the SYNC reproduction signal.

FIG. 9A shows VFO ₃ which is the VFO of the data section.
FIG. 9B shows a pattern of a mark recorded on a WORM disk by, for example, a hole edge method in accordance with the channel bit pattern. Thus, the WORM disk in response to VFO _3, mark 2T is recorded. T
Indicates the time length of one channel bit.

FIG. 10A shows a SYNC channel bit pattern in the data portion, and FIG. 10B shows a mark pattern recorded on a WORM disk in accordance with the channel bit pattern by, for example, a hole edge method. ing. In this manner, W corresponding to SYNC
On the ORM disk, marks such as 4T and 5T are recorded. The bit indicated by “x” in the above-mentioned SYNC channel bit pattern is set to “1” when the subsequent data field starts with “00”, and is set to “0” otherwise.

The asymmetry Asym is the center level a, S determined from the upper and lower envelopes of the VFO ₃ reproduction signal.
From the center level b and the peak-to-peak value c obtained from the upper and lower envelopes of the YNC reproduced signal,
It is calculated as shown in equation (1). Asym = (ba) / c × 100 [%] (1)

FIGS. 11A to 11C schematically show VFO ₃ and SYNC reproduced signals in the data section. 11A is a reproduction signal when the recording power is low and the asymmetry is negative, FIG. 11B is a reproduction signal when the recording power is almost appropriate and the asymmetry is 0, and FIG. The reproduction signal when the asymmetry is positive is shown.

The center of the recording power area (margin) where the error rate is low and data can be read correctly is not at the position where the asymmetry is 0 but at the position where the asymmetry is 10 to 20%. for that reason,
Usually, asymmetry is 10 to 10
A recording power of 20%, for example, 15% is used.

As described above, in the area AR where the recording power is low and the asymmetry is, for example, -30% to -10%, the data that can be read correctly immediately after writing, after several hours to about 40 hours have elapsed. Reading may not be possible due to an increased error rate. Therefore, it is desired that such data writing be set to NG at the time of verification.

In view of the foregoing, it is an object of the present invention to improve the accuracy of verification by making it possible to judge NG at the time of verification even for data writing in which data cannot be read out with the lapse of time due to low recording power. And

[0020]

According to the present invention, there is provided a disk apparatus comprising: a data writing unit for writing data by recording a mark corresponding to data on a disk medium; and a data writing unit for writing data based on the mark recorded on the disk medium. A data reading unit for reading the data; and a verifying unit for checking whether the data written on the disk medium by the data writing unit can be correctly read by the data reading unit. Then, the data readout means is a signal reproduction means for obtaining a reproduction signal from the mark recorded on the disk medium by the optical head, and the readout signal is binarized using the center level of the reproduction signal from the mark having a short mark length as a slice level. A binarizing means, a reproduction signal processing means for processing the output signal of the binarization means to obtain read data, and a signal processing means arranged between the signal reproduction means and the binarization means for boosting a high band of the reproduction signal; And a filter control means for controlling the amount of high-frequency boost in the filter means to be larger than usual when the verifying means performs the above check.

[0021] Also, a verifying method for a disk device according to the present invention comprises a data writing means for writing data by recording a mark corresponding to the data on a disk medium, and a data writing means based on the mark recorded on the disk medium. Data reading means for reading data from a mark recorded on the disk medium, and a data reproducing means for obtaining a reproduction signal from the mark recorded on the disk medium by an optical head; A binarizing means for binarizing the reproduced signal as a level; a reproduced signal processing means for processing an output signal of the binarized means to obtain read data; And a filter means for boosting the high frequency range of the reproduced signal. When checking whether read out the data written on the disk medium correctly by the data reading means by stages, in which greater than normal high frequency boost of the filter means.

At the time of writing data, a mark corresponding to the data is recorded on a disk medium. For example, WOR
Mark edge recording is performed on the M disk by a perforation method.

At the time of reading data, a reproduction signal is obtained from the mark recorded on the disk medium by the optical head. This reproduced signal is subjected to high-frequency boosting by the filter means and then binarized by the binarization means. Then, the output signal of the binarization means is processed to obtain read data.
As a slice level for binarization, a center level of a reproduction signal from a mark having a short mark length is used.

When the recording power is low, the data which can be read correctly immediately after writing may have a high error rate after several hours to about 40 hours, and may not be read. Therefore, at the time of verification for checking whether data written on the disk medium can be correctly read immediately after writing, the high-frequency boost amount in the filter means is made larger than usual.

When the recording power is low, when the amount of high-frequency boost in the filter means increases, the peak-to-peak value of the reproduced signal from a mark having a short mark length increases, and its central level, ie, binarization. Changes in the direction of increasing the error rate. Therefore, the writing of data that may have a low recording power and an error rate becomes high after several hours to about 40 hours and reading becomes impossible is performed at the time of verification.
G.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a WORM disk device 10 as an embodiment.

The disk device 10 has a spindle motor 12 for rotating a WORM disk 11 at a constant angular velocity. The WORM disk 11 has, for example, a sector format as shown in FIG.
130m where user data is 1024 bytes / sector
m WORM disk.

The disk drive 10 has an optical head 13 composed of a laser diode, an objective lens, a photodetector, a preamplifier, and the like, and a laser drive circuit 14 for driving the laser diode of the optical head 13. doing. In this case, the laser drive circuit 14 is supplied with the laser power detection output S _DP from the optical head 13, is supplied with a power control signal S _PC from a system controller described later, and is output from the laser diode of the optical head 13. The power of the laser beam is controlled so as to be the optimum power at the time of recording and at the time of reproduction, respectively.

When writing data, the laser drive circuit 14 is supplied with recording data RD from a channel encoder / decoder described later. Therefore, at the time of data writing, the laser diode of the optical head 13 is driven by the laser drive circuit 14 so that the laser power changes in accordance with the recording data RD. As a result, a mark corresponding to the recording data RD is recorded in the data portion of the WORM disk 11. In this case, mark edge recording is adopted, and marks are recorded in a perforated manner.

[0030] From the optical head 13, during recording and reproduction, with the reproduction signal Sa from the WORM disk 11 is output, conventionally known detection methods obtained it is tracking error signal E _T, and a focus error signal E _F is output Is done.

The disk device 10 has a CPU (centre
ral processing unit). The servo circuit 15 the error signal E _T outputted from the optical head 13, is E _F is supplied. Servo circuit 15
Is controlled by a system controller described later. The servo circuit 15 controls a tracking coil, a focus coil, and an actuator 16 including a linear motor for moving the optical head 13 in the radial direction, and performs tracking and focus servo. Movement in the direction is controlled. Further, the rotation of the spindle motor 12 is controlled by the servo circuit 15, and the WORM
The disk 11 is rotated at a constant angular velocity.

The disk device 10 is a system controller having a CPU (hereinafter referred to as a "syscon").
17 and a buffer memory 1 necessary for continuously inputting data and outputting discretely or vice versa.
8 is provided. The system controller 17 controls the entire system. The disk device 10 is connected to a host computer (not shown) through the system controller 17.

Further, the disk device 10 performs processing for adding an error correction code to write data supplied from the host computer through the system controller 17 and the buffer memory 18, and performs a channel encoder / write operation to be described later.
ECC (error correction code) for performing error correction processing on the read data supplied from the decoder
It has an encoder / decoder 19. The read data output from the ECC encoder / decoder 19 is supplied to the host computer through the system controller 17 and the buffer memory 18.

The disk device 10 obtains recording data RD by performing digital modulation processing on the write data to which the error correction code has been added by the ECC encoder / decoder 19, and outputs the recording data RD from a signal processing circuit described later. A channel encoder / decoder 20 for digitally demodulating the reproduction data Da to obtain read data; and a reproduction signal Sa output from the optical head 13.
Processing circuit 2 for processing the data to obtain reproduction data Da
And 1.

The disk device 10 is provided with an address decoder for obtaining address data AD from reproduced data Da output from the signal processing circuit 21 corresponding to the reproduced signal Sa of the header portion (see FIG. 8) of the WORM disk 11. 2
Two. The address data AD output from the address decoder 22 is supplied to the system controller 17,
It is used for access control during data writing and data reading.

FIG. 2 shows the configuration of the signal processing circuit 21. The signal processing circuit 21 includes a gain control amplifier (GCA) 31 whose gain is controlled so that the amplitude level of the reproduction signal Sa from the 6T mark becomes constant, and a signal output from the gain control amplifier 31. Filter section 32 for performing waveform equalization processing and high-frequency boost processing
And The waveform equalization process is performed to compensate for the frequency characteristics of the reproduction signal Sa. On the other hand, the high-frequency boost processing is based on the MTF (Modulation Transfer Functi) of the optical system.
on) This is performed to compensate for the amplitude deterioration of the high-frequency signal due to the characteristic.

FIG. 3 shows the MTF characteristics of a WORM disk, where the higher the frequency of the signal, the smaller the amplitude. A curve a in FIG. 4 shows a characteristic of a normal high-frequency boost in the filter unit 32. The filter unit 3
The frequency characteristic of No. 2 is controlled by the system controller 17, and at the time of verification for checking whether or not the written data can be read correctly immediately after writing the data, the boost amount in the high frequency range is higher than usual as shown by the curve b in FIG. Is also increased. Here, the frequency fb of the boost peak of the curve b
Is about 1.17 times the frequency fa of the boost peak of the curve a, and the reproduced signal of VFO _{3 in} the data section is selectively boosted.

Returning to FIG. 2, the signal processing circuit 21
Includes a binarization circuit 33 for binarizing an output signal of the filter unit 32 to obtain reproduction data Da;
3 has an envelope detector 34 for supplying a slice level Ls for binarization. The detector 34 detects upper and lower envelope signals from the output signal of the gain control amplifier 31, and adds and averages the upper and lower envelope signals to obtain a center level. Then, a timing signal is supplied from the system controller 17 to the detector 34, and the center level corresponding to the VFO ₃ reproduction signal Sa in the data portion is extracted as the slice level Ls.

The operation of the signal processing circuit 21 shown in FIG. 2 will be described. The reproduced signal Sa is amplified by the gain control amplifier 31 and then supplied to the filter unit 32, where a waveform equalization process and a high-frequency boost process are performed. Then, the filter unit 32
Is supplied to the binarization circuit 33 and the detector 3
The reproduction data Da is obtained by binarization based on the slice level Ls supplied from No. 4.

The operation of the WORM disk device 10 shown in FIG. 1 will be described.

The operation at the time of reading data will be described. The reproduction signal Sa from the optical head 13 is processed by the signal processing circuit 21 to obtain reproduction data Da. Then, the reproduced data Da is supplied to the channel encoder / decoder 20 and subjected to digital demodulation processing, and further supplied to the ECC encoder / decoder 19 and subjected to error correction processing. The read data output from the ECC encoder / decoder 19 is stored in the system controller 17 and the buffer memory 1.
8 to the host computer.

The operation at the time of writing data will be described. At the time of data writing, the system controller 17 operates according to the flowchart shown in FIG.

First, in step ST1, N = 0 is set, and in step ST2, data writing is executed.
In this case, the write data from the host computer is transmitted through the system controller 17 and the buffer memory 18 to the E.
The signal is supplied to a CC encoder / decoder 19 to which an error correction code is added. Thereafter, the signal is supplied to a channel encoder / decoder 20 for digital modulation. And
The recording data RD output from the channel encoder / decoder 20 is supplied to the laser drive circuit 14. Thereby, the laser light output from the laser diode of the optical head 13 is light-intensity-modulated according to the recording data RD,
A mark corresponding to the recording data RD is recorded in the data portion of the WORM disc 11.

Next, in step ST3, the signal processing circuit 2
1 is controlled to increase the high-frequency boost amount from the normal amount (see the curve b in FIG. 4).
Verify, that is, data reading is performed to check whether the written data can be read correctly.

Next, in step ST5, it is checked whether or not the data has been correctly read. In this case, when read data is correctly obtained by performing error correction processing in the ECC encoder / decoder 19, it is determined to be "OK", and otherwise, it is determined to be "NG". If "OK" is determined in step ST5, the filter unit 32 of the signal processing circuit 21 is controlled in step ST6 to return the high-frequency boost amount to normal (see curve a in FIG. 4), and step ST6 is performed.
At 7, the data write operation ends normally.

If "NG" in step ST5,
In step ST8, it is determined whether or not N = No.
For example, No = 3. If N is not equal to No in step ST8, N is incremented in step ST9, and in step ST10, defect processing for writing data to another area (alternate area) is performed, and data is rewritten. Then, returning to step ST4, data reading for verification is executed.

If it is determined in step ST8 that N = No and the read data cannot be correctly obtained by rewriting the data No times, the process proceeds to step ST8.
At 11, it is determined whether or not the recording conditions can be reset, such as resetting the recording power by calibration.
If the recording condition can be reset, step ST1
In 2, the recording conditions are reset, and the process returns to step ST1.
The same operation as described above is performed. On the other hand, if the recording condition has already been reset and it is not possible to reset it further, the high frequency boost amount is returned to normal in step ST13, and the data writing operation is abnormal in step ST14. finish.

As described above, in the present embodiment, in the operation at the time of data writing, at the time of verifying whether or not the written data can be read correctly, the filter unit 32 of the signal processing circuit 21 is controlled to perform the normal operation. The higher frequency boost amount is increased. For this reason, data writing that has a low recording power and an error rate becomes high after a lapse of several hours to about 40 hours and reading may not be possible can be determined as NG at the time of verification.
The accuracy of verification can be increased.

That is, the solid line in FIG. 6 shows the VF of the data portion when the recording power is low and the high-frequency boost amount is normal.
₃ shows a reproduction signal of O ₃ and a data field.
When the recording power is low, the level of the reproduced signal of the data field does not change steeply at the mark end, and a so-called shoulder is lowered. When the high frequency boost amount is normal, the peak-to-peak value of the VFO ₃ reproduction signal is small, and the slice level Ls1 in the binarization circuit 33 is small.
Is close to the level on the space (land) side of the reproduced signal of the data field. Therefore, the reproduction data Da corresponding to the mark length is obtained from the reproduction signal of the data field.
Can be obtained.

On the other hand, when the high-frequency boost amount becomes larger than usual, the peak-to-peak value of the VFO ₃ reproduction signal becomes larger as shown by the broken line in FIG. The level Ls2 changes in a direction away from the level on the space side of the reproduced signal of the data field. Therefore, it is difficult to obtain the reproduction data Da corresponding to the mark length from the reproduction signal of the data field, the error rate is deteriorated, the data cannot be read correctly, and NG can be obtained at the time of verification.

In the above-described embodiment, the present invention is applied to a WORM disk device. However, the present invention can be similarly applied to other disk devices such as a magneto-optical disk device.

[0052]

According to the present invention, at the time of verifying whether data written on a disk medium can be read correctly, the boost amount of a high frequency of a reproduction signal is made larger than usual, and a state where recording power is low is obtained. In this case, the error rate of reading out the data written in step (1) is deteriorated. Therefore, it is possible to determine NG at the time of verifying even when writing data in which the recording power is low and data cannot be read out with the lapse of time, and
The accuracy of verification can be increased.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a WORM disk device as an embodiment.

FIG. 2 is a block diagram illustrating a configuration of a signal processing circuit of the WORM disk device.

FIG. 3 is a diagram showing MTF characteristics of an optical disc.

FIG. 4 is a diagram illustrating a high-frequency boost characteristic of a filter unit of the signal processing circuit.

FIG. 5 is a flowchart showing the operation of the system controller when writing data.

FIG. 6 is a diagram showing a reproduced signal when the recording power is low.

FIG. 7 is a diagram showing the relationship between recording power, asymmetry, and error rate.

FIG. 8 is a diagram showing a sector format of a 130 mm WORM disk in which user data is 1024 bytes / sector.

FIG. 9 is a diagram showing a channel bit pattern and the like of VFO ₃ ;

FIG. 10 is a diagram illustrating a SYNC channel bit pattern and the like.

FIG. 11 is a diagram for explaining a relationship between recording power and asymmetry.

[Explanation of symbols]

10 WORM disk device, 11 WORM
Disk, 13 optical head, 14 laser drive circuit, 15 servo circuit, 16 actuator, 17 system controller, 18 buffer memory, 19 ECC encoder / Decoder, 20... Channel encoder / decoder, 21.
..Signal processing circuits, 31... Gain control amplifiers, 32
... Filter unit, 33 ... Binary circuit, 34 ...
Envelope detector

Claims (4)

[Claims] 1. A data writing means for writing data by recording a mark corresponding to data on a disk medium, a data reading means for reading the data based on the mark recorded on the disk medium, Verifying means for checking whether or not data written to the disk medium by the data writing means can be correctly read by the data reading means, wherein the data reading means uses a mark recorded on the disk medium. Signal reproducing means for obtaining a reproduced signal by an optical head; binarizing means for binarizing the reproduced signal with the center level of the reproduced signal from a mark having a short mark length as a slice level; output of the binarizing means Reproduction signal processing means for processing a signal to obtain read data Filter means arranged between the signal reproducing means and the binarizing means for boosting a high frequency range of the reproduced signal; and a high frequency range of the filter means when the verifying means performs the check. A disk control device for controlling the boost amount to be larger than usual. 2. The disk device according to claim 1, wherein the disk medium is a write-once optical disk. 3. The disk drive according to claim 1, wherein said data writing means performs mark edge recording. 4. A data writing means for writing data by recording a mark corresponding to data on a disk medium, and a data reading means for reading the data based on the mark recorded on the disk medium. The data reading means comprises: signal reproducing means for obtaining a reproduction signal from the mark recorded on the disk medium by an optical head; and a center level of the reproduction signal from a mark having a short mark length as a slice level. A binarizing unit for performing binarization, a reproduction signal processing unit for processing an output signal of the binarization unit to obtain read data, and being disposed between the signal reproduction unit and the binarization unit; A disk device having filter means for boosting a high frequency range of a reproduction signal, wherein the data writing means And verifying whether or not the data written on the disk medium can be correctly read by the data reading means. .