JP2000298833A - Drive device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To determine whether recording laser power is appropriate or not at the time of verification. SOLUTION: It is determined whether or not the laser power at the time of recording is appropriate based on whether or not an asymmetry value or an amplitude value of a data signal waveform is within a predetermined range. When it is determined that the laser power at the time of recording is not appropriate, the recording laser power is adjusted and the recording operation is retried.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device capable of reproducing data from a recording medium.

[0002]

2. Description of the Related Art In a drive device that performs a recording / reproducing operation on a recording medium such as an optical disk, a magneto-optical disk, etc., when recording is performed on a certain sector (a sector is a data unit on the recording medium), Then, an operation of reproducing the sector and checking whether data has been correctly recorded is performed. Such an operation is called write-and-verify. Especially write-once type disks (W
For an ORM disc, it is not possible to rewrite, so it is important to perform write and verify during recording.

At the time of verification, reproduction is performed under stricter read conditions than during normal reproduction. If the data can be read properly under the severe conditions, it is determined that the verification is OK (that is, the recording is OK). This is to ensure that the disc can be properly reproduced even when the disc is loaded into a reproducing apparatus having a low read capability.
On the other hand, if the verification has failed, the recording operation is performed again as a retry operation. In the case of a write-once disk, it is not possible to perform writing again on a sector that has been written once, so that recording is performed on a different sector during the retry operation.

As a method for making read conditions stricter during verification, for example, ECC criteria (error correction O
For example, the criterion of K) and the resync criteria (criterion of synchronization error) are made strict, the amplitude of the reproduced RF signal is reduced, and the binarized slice level is changed.

[0005] The main causes of the verification NG include scratches and dirt (defects) on the disk and inappropriate laser power at the time of recording. It is only necessary to be able to adjust the recording laser power to the optimum level at the time of recording.However, with a write-once disc, performing trial writing many times at the time of recording and adjusting the recording laser power will reduce sector consumption. It is not appropriate because it would significantly expand. Therefore, when the recording laser power is inappropriate, it is important to determine that the recording laser power is NG at the time of verification and change the recording laser power to perform a retry.

[0006]

By the way, if the verification is performed under strict read conditions such as the ECC criteria and the resync criteria, if the sector has a large defect, the verify N is almost certainly achieved.
G. That is, when it is determined that a recording error has occurred, verify NG is appropriately performed, and recording can be performed again on another sector having no defect by a retry operation.

However, considering a case where there is a problem with the recording laser power, for example, a case where the recording laser power is too low and a drive device having a high read capability even when read conditions are strict. In some cases, data can be properly reproduced at the time of verification. Currently, the bit-by-bit decoding method and the Viterbi decoding method are often used as the reproduction system of the drive device.However, the Viterbi decoding method has a very high read capability, so even if the recording laser power is inappropriate. In most cases, the verification is OK. If the verification is OK even if the recording laser power is inappropriate as described above, the retry operation will not be performed as it is as recording OK, but if the disc uses a bit-by-bit decoding method, If the data is loaded in the memory, it is highly likely that the data cannot be reproduced.

That is, if the verification NG is changed to the verification OK, the reproduction compatibility cannot be maintained, and the reliability of the recording / reproduction system is impaired. In other words, if verification is performed only under strict read conditions, the verification OK / N
It is insufficient to use G as a reference for OK / NG of the recording operation. Further, when the verification is NG, there is a problem that it is not possible to clearly determine whether or not the recording laser power is inappropriate as a cause thereof, so that an appropriate retry cannot be executed (it is clear whether or not the laser power should be changed. I don't know).

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in view of the above circumstances. It is an object of the present invention to enable operations to be performed and thereby maintain good reproduction compatibility.

[0010] For this purpose, the drive device of the present invention provides a head means capable of recording data on a recording medium by irradiating a laser beam and reading out a recorded data signal, and a head device capable of reading out the recorded data signal. Decoding means for performing decoding processing on a data signal to obtain reproduced data, asymmetry calculating means for calculating an asymmetry value for a data signal waveform read by the head means, and supplying recording data to the head means. After the data is recorded on the recording medium, the data signal is read out from the recorded data, and whether or not the asymmetry value calculated by the asymmetry calculating means for the data signal waveform is within a predetermined range. It is determined whether the laser power at the time of recording is appropriate according to
If it is determined that the laser power at the time of recording is not appropriate, a control means for determining a recording operation error (for example, a verify NG state to shift to a retry operation) is provided.

Among recordable disc media, for example, WORM discs are those that form embossed pits on a disc by irradiating a laser beam, so-called perforated types, and those that record data by a phase change method. Further, there is a type called an alloy type which forms a pit due to a change in reflectance. Further, as rewritable disk media, there are a magneto-optical disk (MO disk) in which magnetic field pits are formed, and a disk using a phase change method such as a DVD-RAM and a DVD-RW. Among them, there is a correlation between the recording laser power and the asymmetry of the reproduced data signal except for the alloy type WORM disk.
Therefore, it is possible to determine whether the recording laser power is appropriate by calculating the asymmetry value.

Also, a drive device according to the present invention includes a head device capable of recording data on a recording medium by irradiating a laser beam and reading a recorded data signal, and a data device read by the head device. Decoding means for performing decoding processing on a signal to obtain reproduced data; amplitude calculating means for calculating an amplitude value of a data signal waveform read by the head means; and supplying recording data to the head means. After the recording of the data on the recording medium is performed, the reading of the data signal for the recorded data is performed, and whether the amplitude value calculated by the amplitude calculating means for the data signal waveform is within a predetermined range or not. Determines if the laser power during recording is appropriate, and determines that the laser power during recording is not appropriate , So that a control means for determining a recording operation error.

In the alloy type WORM disk and the like, there is a correlation between the recording laser power and the amplitude level of a reproduced data signal. Therefore, by calculating the amplitude value, it can be determined whether or not the recording laser power is appropriate.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described, but in order to facilitate understanding of the embodiments,
In the following order, first, the configuration of a disk drive device having a reproduction system that performs the Viterbi decoding method, the Viterbi decoding method, and the like will be described, and then, the configuration and operation of the disk drive device as an embodiment will be described. 1. 1. Description of disk drive device having playback system for performing Viterbi decoding method 1-1 Overview of device configuration 1-2 Viterbi decoding method 1-3 Viterbi decoder 2. 2. Disk drive device (I) of embodiment 2-1 Configuration of disk drive device 2-2 Relationship between recording laser power and asymmetry 2-3 Write-and-verify process 2-4 Example of operation mode of write-and-verify Disk drive device (II) of embodiment 3-1 Relationship between recording laser power and amplitude 3-2 Write-and-verify processing and operation example

1. 1. Description of Disk Drive Device Having Reproduction System Performing Viterbi Decoding Method 1-1 Overview of Device Configuration First, an example of a typical disk drive device (recording / reproduction device) having a reproduction system performing a Viterbi decoding method will be described. FIG. 1 is a block diagram showing a configuration of an example of a disk drive device having a reproducing system for performing a Viterbi decoding method on a magneto-optical disk or an optical disk. However, in this figure, the servo system and the like are omitted.

At the time of recording, the controller 2 receives user data to be recorded according to a command from the host computer 1, performs encoding based on the user data as information words, and performs RLL (1, 7) encoding as code words. Generate This code word is supplied as recording data to a laser power control unit (hereinafter, referred to as LPC) 4. In addition to such processing, the controller 2 performs operations such as decoding processing described later, control of each mode such as recording, reproduction, and erasing, and communication with the host computer 1.

The LPC 4 generates a laser drive signal (drive pulse) so as to execute laser output from the optical pickup 7 at each of reproduction, recording, and erasing. This drive pulse is APC (Auto Power C
and a drive section (hereinafter, APC) 10 to apply a current corresponding to a drive pulse to the laser diode by the APC 10, thereby performing laser output from the laser diode in the optical pickup 7. Further, the APC 10 performs feedback control so as to keep the laser level at a predetermined value.

As described above, the LPC 4 and APC 10 control the laser power of the optical pickup 7 in accordance with the supplied recording data to form a pit row on the disk 6 rotated by the spindle motor 9. Thus, recording is performed. For example, in the case of a drive device corresponding to a rewritable magneto-optical disk (MO disk),
A pit row having a magnetic polarity is formed on the disk 6. In this case, the magnetic head 5 applies a bias magnetic field to the disk 6. In addition, a write-once disc (WORM)
Disk) and a drive device that supports so-called abrasive type (perforated) disks,
An emboss pit row is formed by the laser beam. In the case of a write-once disk (WORM disk), which is a drive device corresponding to a so-called alloy type disk, a pit row is formed by causing a change in the reflectance of the disk recording surface by laser light. Further, in the case of a drive device corresponding to a phase change type disk, a phase change pit row is formed by a laser beam. ,

In the pit train, mark edge recording described later is performed in accordance with a precode output generated as described later based on the recording data. A method for associating each pit to be formed with each pit in a precode output generated as described later based on the recording data will be described with reference to FIG. A pit is formed for, for example, “1” during precode output,
A recording method in which no pit is formed for 0 'is called a mark position recording method. On the other hand, a recording method in which the polarity inversion at the boundary of each pit in the precode output expressed by the edge of each pit corresponds to, for example, “1” is referred to as a mark edge recording method. At the time of reproduction, the boundary of each pit in the reproduction signal is recognized according to a read clock DCK generated as described later.

The configuration and operation of the reproduction system shown in FIG. 1 are as follows. The optical pickup 7 irradiates the disk 6 rotated by the spindle motor 9 with laser light, receives reflected light generated by the laser light, and generates reflected light information. Although not described in detail, the reflected light information includes a focus error signal and a tracking error signal in addition to the reproduced RF signal corresponding to the reproduced data. As a reproduction RF signal, for example, a magneto-optical disk
In a sector format on a disk, if there is a portion where an embossed pit is formed and a portion where a pit row is recorded magneto-optically, there are two types of so-called sum signal and difference signal. Switching processing is performed accordingly.

The RF signal is supplied to the filter section 11 after gain adjustment and the like are performed by the amplifier 8. The filter unit 11 includes a low-pass filter that performs noise cut and a waveform equalizer that performs waveform equalization. As will be described later, the waveform equalization characteristics used in the waveform equalization process at this time are adapted to the Viterbi decoding method performed by the Viterbi decoder 13. The A / D converter 12 to which the output of the filter unit 11 is supplied samples the reproduction signal value z [k] in accordance with a read clock DCK supplied as described later.

The Viterbi decoder 13 outputs a reproduced signal value z [k]
, And generates decoded data by the Viterbi decoding method. Such decoded data is a maximum likelihood decoded sequence for the recorded data recorded as described above. Therefore,
If there is no decoding error, the decoded data matches the recorded data. The Viterbi decoder 13 includes a branch metric block (BMC) 132, an add compare select block (ACS) 133, a status memory unit (SMU) 134, and a merge block 135. These will be described later. The Viterbi decoder 13 also includes a shift register 131 and an amplitude reference value adaptation unit (RAA) 136. And A / D converter 1
The output of 2 is also supplied to the shift register 15, and after being given a predetermined delay time by the shift register 131, is supplied to the amplitude reference value adaptation unit (RAA) 136. These operations will also be described later.

The decoded data obtained by the Viterbi decoder 13 is supplied to the controller 2. As described above, the recording data is a codeword generated from user data by encoding such as channel encoding. Therefore,
If the decoding error rate is sufficiently low, the decoded data can be regarded as recording data as a codeword. The controller 2 reproduces user data and the like by performing a decoding process corresponding to the above-described encoding such as the channel encoding on the decoded data.

The output of the filter unit 11 is also supplied to a PLL unit 14. The PLL unit 14 generates a read clock DCK based on the supplied signal. This P
The LL unit 14 is configured to detect a phase error by using a signal of a constant frequency recorded in the magneto-optical disk 6, for example. The read clock DCK is supplied to the controller 2, the A / D converter 12, the Viterbi decoder 13, and the like. The operations of the controller 2, the A / D converter 12, and the Viterbi decoder 13 are performed at timing according to the read clock DCK.

1-2 Viterbi decoding method A Viterbi decoding method performed by the Viterbi decoder 13 will be described below. As described above, the user data is converted into a codeword as recording data by various encoding methods. An appropriate encoding method is adopted according to the characteristics of the recording medium and the recording / reproducing method. In the disk drive device shown in FIG. 1, in block encoding, an RLL (Run Length Limited) encoding method for limiting the number of "0" between "1" and "1" is used. A Viterbi decoding method can be used to decode a reproduction signal reproduced from data recorded by a combination of such an RLL encoding method and the above-described mark edge recording method.

Such an RLL encoding method can meet the conditions required for the encoding method from two viewpoints of improving the recording density and ensuring the stability of the reproducing operation. First, as described above, the mark edge recording method associates "1" in a precode output generated as described later based on recording data with the inversion of the polarity represented by the edge of each pit. "
As the number of "0" s between "1" and "1" is increased, the number of pits recorded per l pits can be increased, and the recording density can be increased.

On the other hand, the reproduction clock DCK necessary for adjusting the operation timing of the reproduction system is, as described above,
It is generated by the PLL section 14 based on the reproduction signal.
For this reason, in the recording data, "1" and "1"
When the number of 0 "s is increased, the operation of the PLL unit 14 becomes unstable during the reproducing operation, so that the entire reproducing operation becomes unstable.

Considering these two conditions, "1"
The number of “0” s between “1” and “1” needs to be set within an appropriate range that is neither too large nor too small. Regarding the setting of the number of “0” in the recording data, R
The LL encoding method becomes effective.

By the way, as shown in FIG.
In the combination of the LL (1,7) encoding method and the mark edge recording method, at least one "1" is inserted between "1" and "1" in the precode output generated based on the recording data.
Since 0 ”is included, the minimum inversion width (RLmin) is 2. When such an encoding method with the minimum inversion width of 2 is used, it is affected by intersymbol interference and noise. As a method for decoding recorded data from a reproduced signal, a 4-level 4-state (6-level 4-state) Viterbi decoding method can be applied as described later.

As described above, the reproduced signal is subjected to the waveform equalization processing by the filter unit 11. Such a waveform equalization process performed as a preceding stage of the Viterbi decoding method includes:
A partial response method that actively uses intersymbol interference is used. The waveform equalization characteristics used at this time are:
From the partial response characteristics generally represented by (1 + D) ⁿ , the linear recording density and MTF (M
odulation transfer function).
For data recorded by a combination of the RLL (1,7) encoding method and the mark edge recording method described above,
The waveform equalization processing using PR (1,2,1) is a preceding stage of the 4-value 4-state Viterbi decoding method.

As shown in FIG. 3, in the mark edge recording method, prior to actual recording on a magneto-optical disk or the like, precoding based on the recording data encoded by the above-described RLL encoding or the like is performed. Assuming that the recording data sequence at each time point k is a [k] and the precode based on this is b [k], the precoding is performed as follows. b [k] = mod2 {a [k] + b [k-1]} (1) Such a precode output b [k] is actually recorded on the disk 6.

When such recorded data is reproduced, a waveform equalization characteristic P made by the waveform equalizer in the filter unit 11 is obtained.
The waveform equalization processing at R (1, 2, 1) will be described. However, in the following description, the waveform equalization characteristic is PR (B, 2A, B) without normalizing the signal amplitude. The value of the reproduced signal when noise is not taken into account is denoted by c [k]. Further, an actual reproduced signal including noise (that is, a reproduced signal reproduced from the disk 6) is denoted by z [k].

PR (B, 2A, B) indicates that the contribution of the amplitude at the time point k to the value of the reproduced signal at a certain time point k is 2A times the amplitude value. The contribution of the amplitude is B times the amplitude of the signal at each point in time. Therefore, the maximum value of the value of the reproduction signal is a case where a pulse is detected at any of the time points k−1, k, and k + 1. In such a case,
The maximum value of the reproduction signal is as follows.

B + 2A + B = 2A + 2B The minimum value of the reproduced signal is 0. However, in the actual handling, A + B of the DC component is used as c [k].
The following is used by subtracting c [k] = B * b (k-2) + 2A * b (k-1) + B * b [k] -AB (2)

Therefore, the reproduction signal c [k] when noise is not taken into account takes any one of A + B, A, -A, and -AB. In general, as one of the methods for indicating the properties of a reproduced signal, a pattern obtained by superimposing a large number of reproduced signals in units of, for example, five points is called an eye pattern. FIG. 4 shows an example of an eye pattern of an actual reproduced signal z [k] which has been subjected to waveform equalization under PR (B, 2A, B) in a recording / reproducing apparatus to which the present invention can be applied. From FIG. 4, the reproduced signal z [k] at each time point
Has a variation due to noise, but is approximately A +
It can be confirmed that any one of B, A, -A, and -AB is obtained. As described later, A + B, A, -A, -AB
Is used as an identification point.

The outline of the Viterbi decoding method for decoding the reproduced signal subjected to the above-described waveform equalization processing is as shown in steps 1 to 3. Step: Specify all possible states based on the encoding method and the recording method for the recording medium. Step: Starting from each state at a certain time point, all possible state transitions at the next time point, and the recording data a [k] and the value c [k] of the reproduction signal at the time of each state transition are specified. . Note that all states and state transitions specified as a result of the step and the state, and {recorded data value a [k] / reproduction signal value c [k]} when each state transition occurs are schematically shown. This will be a state transition diagram as shown in FIG. 6, which will be described later. The Viterbi decoder 13 is configured to perform a decoding operation based on this state transition diagram.

On the premise of the state transition shown in step..., The maximum likelihood state transition based on the reproduction signal z [k] reproduced from the recording medium at each time point k is selected. However, as described above, the reproduction signal z [k] has been waveform-equalized in a stage before being supplied to the Viterbi decoder 13. Each time such a maximum likelihood state transition is selected, the value of the recording data a [k] is set as a decoded value in accordance with the selected state transition, so that a maximum likelihood decoded value sequence for the recording data is obtained. Can be obtained as decoded data a ′ [k]. Alternatively, a state data value representing the selected state transition itself can be obtained. In the example of FIG. 1, the state data value sm [k +
[n].

Hereinafter, the above steps 1 to 5 will be described. First, the steps will be described in detail. As the state used here, the state at a certain time point k is defined as follows using the precode output before the time point k. That is, n = b [k], m = b [k−1],
The state when l = b [k-2] is defined as Snml. With such a definition, it is considered that there are 2 ³ = 8 states, but as described above, the states that can actually occur are limited based on the encoding method and the like. In the recording data sequence a [k] encoded as the RLL (1, 7) code, "
Since at least one “0” is included between “1” and “1”,
Two or more “1” s do not continue. Based on such conditions imposed on the recording data string a [k], certain conditions are imposed on the precode output b [k], and the resulting states are restricted.

The above-mentioned restriction is specifically as follows. As described above, in the recording data sequence generated by the RLL (1, 7) encoding, there is no pattern in which two or more “1” s are continuous, that is, the following pattern. a [k] = 1, a [k−1] = 1, a [k−2] = 1 (3) a [k] = 1, a [k−1] = 1, a [k− 2] = 0 (4) a [k] = 0, a [k−1] = 1, a [k−2] = 1 (5) Such a kind imposed on the recording data sequence Considering the conditions imposed on b [k] in accordance with the above equation (1) based on the conditions, it is found that S0 in the definition of Snml.
It can be seen that the two states of 10 and S101 cannot occur. Therefore, there are 2 ³ −2 = 6 possible states.

Next, the steps will be described. To obtain a state that can occur at the next time point j + 1 starting from the state at a certain time point j, the value a [j + 1] of the recording data at the time point j + 1 becomes 1 or 0
It is necessary to investigate separately when it becomes.

Here, the state S000 will be described as an example. According to the above equation (1), S000, that is, n =
b [j] = 0, m = b [j-1] = 0, l = b [j-2] = 0
The following two are conceivable as recording data pre-coded as follows. a [j] = 0, a [j-1] = 0, a [j-2] = 1 ... (6) a [j] = 0, a [j-1] = 0, a [j- 2] = 0 (7)

When a [j + 1] = 1 At this time, b [j + 1] is calculated as follows according to the equation (1). Therefore, the value of the reproduced signal c [j] is calculated as follows according to the above equation (2).

C [j + 1] = {B × b [j + 1] + 2A × b [j] + B × b [j−1] −AB = {B × 1 + 2A × 0 + B × 0} −AB = −A ... (9)

The state Snml at the next time point [j + 1]
For n = b [j + 1], m = b [j], 1 = b [j
-1]. Then, as described above, b [j + 1] =
Since 1, b [j] = 0 and b [j-1] = 0, the state at the next time point, j + 1, is S100. Therefore, when a [j + 1] = 1, it can be specified that a transition of S000 → S100 occurs.

When a [j + 1] = 0 At this time, b [j + 1] is calculated as follows according to the equation (1). Therefore, the value of the reproduced signal c [j + 1] is calculated as follows according to the above equation (2).

C [j + 1] = {B × b [j + 1] + 2A × bj] + B × b [j−1]} − AB = {B × 0 + 2A × 0 + B × 0} −AB = −A− B ... (11)

The state Snm at the next time point j + 1
For l, n = b [j + 1], m = b [j], l = b
[j-1]. Then, as described above, b [j + 1] =
Since 0, b [j] = 0 and b [j-1] = 0, the state at the next point in time is S000. Therefore, a [j
In the case of +1] = 0, it can be specified that a transition of S000 → S000 occurs.

Thus, S000 at time j
, The state transitions that can occur at the next time point j + 1 starting from them and the correspondence between the recording data value a [j + 1] and the reproduction signal value c [j + 1] when such state transitions occur Can be requested.

As described above, for each state, the correspondence between the state transition that can occur starting from the state and the value of the recording data and the value of the reproduction signal when each state transition occurs is shown as a schematic diagram. FIG. Time points j and j + 1 described above are not special time points. Therefore, the correspondence between the possible state transitions obtained as described above and the accompanying values of the recording data and the values of the reproduction signals can be applied at any time. For this reason, in FIG. 5, the value of the recording data accompanying the state transition occurring at an arbitrary time point k is denoted as a [k], and the value of the reproduced signal is denoted as c [k].

In FIG. 5, state transitions are represented by arrows. Further, the sign given to each arrow is Δrecorded data value a
[k] / reproduced signal value c [k]}. State S00
There are two types of state transitions starting from 0, S001, S111, and S110, whereas only one transition can occur starting from states S011 and S100. Further, in FIG. 5, S000 and S001 both take a value of c [k] = − A for a [k] = 1, and have transited to S100. On the other hand, for a [k] = 0, a value of c [k] =-AB is taken and the process transits to S000. Similarly, S111 and S110 have the same a
The value of [k + 1] has the same value of c [k + 1], and the state transits to the same state. Therefore, S000 and S001 are collectively expressed as S00, and S111 and S11
0 can be collectively expressed as S11. further,
FIG. 6 shows an arrangement in which S011 is expressed as S10 and S100 is expressed as S01.

FIG. 6 is a state transition diagram used in the 4-level 4-state Viterbi decoding method. For example, when there are four states such as a four-level four-state Viterbi decoding method or the like, these four states can be expressed by two bits, and such two-bit data can be used as a state data value. . Therefore, in FIG. 6, each state is represented by S0 using the 2-bit state data values 00, 01, 11, and 10, respectively.
0, S01, S11, and S10.

In addition, a trellis diagram as shown in FIG. 7 is used as a format for expressing the state transition along time corresponding to FIG. FIG. 7 shows a transition between two time points, but a transition between a larger number of time points may be shown. As the time elapses, a state in which the image sequentially transits to the right time point is expressed. Therefore, a horizontal arrow indicates, for example, S0
A transition to the same state such as 0 → S00 is shown, and an oblique arrow represents a transition to a different state such as S01 → S11.

Assuming the steps of the above-described Viterbi decoding method, that is, the state transition diagram shown in FIG. 6, a method of selecting the most likely state transition from the actual reproduced signal z [k] including noise is as follows. Become.

In order to select the maximum likelihood state transition, first, for the state at a certain time point k, the sum of the likelihoods of the state transitions between a plurality of time points passed in the process of reaching the state is calculated. It is necessary to select the maximum likelihood decoded sequence by comparing the calculated sums of likelihoods. Such a sum of likelihoods is called a path metric.

In order to calculate a path metric, it is first necessary to calculate the likelihood of a state transition between adjacent time points. Such calculation of likelihood is performed as follows based on the value of the reproduced signal z [k] with reference to the above-described state transition diagram. First, as a general explanation, the time k-
Consider the case where the state is Sa in state No. 1. At this time, when the reproduction signal z [k] is input to the Viterbi decoder 13, the likelihood that a state transition to the state Sb occurs is calculated according to the following equation. However, the state Sa and the state Sb are any of the four states described in the state transition diagram of FIG.

(Z [k] −c (Sa, Sb)) ² ... (12) In the above equation, c (Sa, Sb) is a state transition from the state Sa to the state Sb in the state of FIG. This is the value of the reproduced signal described in the transition diagram. That is, in FIG. 7 described above, for example, for the state transition S0 → S1, the value is calculated as −A. Therefore, equation (12) is the Euclidean distance between the value of the actual reproduced signal z [k] including noise and the value of the reproduced signal c (Sa, Sb) calculated without considering noise. The path metric at a certain point in time is defined as the sum of likelihoods of state transition between such adjacent points up to that point.

1-3 Viterbi Decoder In the Viterbi decoder 13, BMC 132, ACS 133,
The SMU 134 detects state data corresponding to the state transition as described above, and the merge block 135 decodes the state data, whereby the controller 2
Can be supplied with the decoded data. The configuration and operation of the Viterbi decoder 13 will be described.

In the following description, P (P, B, 2A, B) is used as the waveform equalization characteristic instead of PR (B, 2A, B).
It is assumed that R (α, β, γ). This premise takes into account that it is difficult to obtain an ideal partial response characteristic in an actual disk drive device, and the waveform equalization characteristic is often asymmetric. The reasons why it is difficult to obtain the ideal partial response characteristics include the limitation of the operation accuracy of the waveform equalizer, the asymmetry (asymmetry of the waveform) due to the laser power during recording being too large or too small, and the reproduction signal. There is a phase error of the read clock used when sampling is performed by the A / D converter 12.

In the case of the four-value four-state Viterbi decoding method, RLL (1, 7) coding or the like is performed at the time of recording such that RLmin = 2, and the partial response characteristic at the time of reproduction is PR (α, β). , Γ), it can be seen that there are six values and four states. That is, for each of 2 ³ −2 = 6 {b [j−1], b [j], b [j + 1]} sets other than the two states excluded by the condition of RLmin = 2, , Ie, the reproduced signal value c [j + 1] after waveform equalization in an ideal case with no noise takes a different value. (Ideally four values, but in reality c011 and c110, and c100 and c001 described below
Do not match, and therefore have six values. )

The values of the six discrimination points are denoted as cpqr. Here, p, q, and r are b [j−
1], b [j] and b [j + 1]. In FIG. 6, the values cpqr of the identification points relating to the transitions of the respective states S00, S01, S11, and S10 are added. That is, c00
0, c001, c011, c111, c110, c10
0. Since RLmin = 2, c010
And c101 do not exist. The following description is made on the premise that the 6 values and 4 states follow the state transition diagram of FIG.

The branch metrics calculated corresponding to the six state transitions in FIG. 6 are described as follows. First, two-bit state data values indicating the state before the transition and the state after the transition are written and arranged to form a sequence of four numbers. Next, a branch metric that can occur during one read clock is expressed as a sequence of three numbers by using the two numbers (ie, the second and third numbers) near the center as one number. . For example, state transition S11 →
The branch metric associated with S10 is denoted by bm110. In this way, the branch metrics corresponding to the six types of state transition in FIG. 6 can be represented as shown in FIG.

Further, the branch metric defined as the Euclidean distance between the actual reproduced signal value z [k] sampled by the A / D converter 12 operating according to the read clock and the value of each discrimination point is as follows. Is calculated.

Bm000 = (z [k] −c000) ² ... (13) bm001 = (z [k] −c001) ² ... (14) bm011 = (z [k] −c011) ^2. (15) bm111 = (z [k] -c111) ² ... (16) bm110 = (z [k] -c110) ² ... (17) bm100 = (z [k] -c100) ^2. (18) When the branch metric is calculated in this way, the value of each discrimination point is directly used as the amplitude reference value. When a standardized path metric is used for the purpose of avoiding the square calculation or the like, the branch metric corresponding to the standardized path metric is different from those according to the equations (13) to (18). In such a case, the value of each identification point cannot be used as it is as the amplitude reference value, but the present invention can be applied.

Using the value of such a branch metric, the path metric mij of the state Sij at the time point k
[K] is calculated as follows. m10 [k] = m11 [k-1] + bm110 (19) m11 [k] = min {m11 [k-1] + bm111, m01 [k-1] + bm011} (20) m01 [k ] = M00 [k-1] + bm001 (21) m00 [k] = min {m00 [k-1] + bm000, m10 [k-1] + bm100} (22)

As shown in FIG. 1, the output of the A / D converter 12 is supplied to the BMC 132 and the shift register 131 in the Viterbi decoder 13. The Viterbi decoder 13
Based on the reproduction signal value z [k] supplied from the A / D converter 12, the BMC 132, ACS 133, SMU 134
The state transition sm [k + n] expressing the selected state transition itself is generated by selecting the maximum likelihood state transition by the above operation. Then, based on the state data, the merge block 135
To generate the decoded data and supply it to the controller 2. The controller 2 performs a decoding process based on the supplied decoded data and reproduces user data, address data, and the like, similarly to the above-described example of the magneto-optical disk device.

The status data from the SMU 134 is also supplied to an amplitude reference value adaptation unit (RAA) 136. Further, the shift register 131 delays the reproduction signal value z [k] supplied from the A / D converter 12 by a predetermined time to RA
A136. This delay is performed to adjust the timing so that the state data generated by the Viterbi decoder 13 has a delay of n read clocks with respect to the reproduced signal value z [k]. Therefore,
The state data value generated by the SMU 134 in the Viterbi decoder 13 is represented by sm [k + n] because of this delay time.

The RAA 136 stores the state data value sm [k + n] supplied at each time point and the shift register 13.
Based on the reproduction signal value z [k] delayed by n clocks at 1, the amplitude reference value is updated for each read clock.
Then, the updated amplitude reference value is stored in B in the Viterbi decoder 13.
Supply to MC132.

Here, each block in the Viterbi decoder 13 will be described. Each block in the Viterbi decoder 13, ie, BMC 132, ACS 133, SMU 134,
Merge block 135, shift register 131, RAA
136 is supplied with a read clock DCK (hereinafter, also simply referred to as a clock) from the PLL unit 14 and the operation timing is adjusted.

The BMC 132 calculates the branch metrics bm000 to bm111 according to the above equations (13) to (18) based on the amplitude reference value supplied from the RAA 16 based on the reproduced signal value z [k]. The calculated branch metric is supplied to the ACS 133.

The ACS 133 calculates the value of the path metric according to the equations (19) to (22) based on the supplied branch metric value, and selects the most likely state transition by comparing the calculated values. . And the selection signal S
EL00 and SEL11 are supplied to the SMU 134.

The SMU 134 will be described with reference to FIG. The SMU 134 performs processing in units of 2-bit state data values, and the processing generates state data as a series of state data values sm [k + n].

As shown in FIG. 8, the SMU 134 has two A-type status memories 150 and 151 and two B-type status memories 152 and 153. Further, select signals SEL00, SEL11, clock,
In addition, a signal line for transferring state data to and from another status memory is connected. The A-type status memories 150 and 151 store the states S00 and S, respectively.
Corresponds to 11. The B-type status memories 152 and 153 correspond to states S01 and S10, respectively. The connection between these four status memories is in accordance with the state transition diagram of FIG.

FIG. 9 shows the configuration of the A-type status memory 150 corresponding to the state S00. The A-type status memory 150 has n processing stages. That is, n selectors 201-0 to 201- (n-1) and n registers 202-0 to 202- (n-1) are alternately connected. The select signal SEL00 is supplied to each of the selectors 201-0 to 201- (n-1). Further, as described above, the status data inherited from the B-type status memory 153 corresponding to S10 is supplied to each selector as PM3 having n bits. As described above, the status data inherited by the B-type status memory 152 corresponding to S01 is output to each register as PM0 including n-1 status data values. Further, a clock is supplied to each of the registers 202-0 to 202- (n-1).

The operation of each selector will be described. FIG.
As shown in (1), the state one clock before which can make a transition in S00 is either S00 or S10. When the state one clock before is S00, a transition that inherits itself is performed. Therefore, the first-stage selector 201
As “-0”, “00” is input as the latest state data value in the state data generated by the serial shift. Selector 201-0 has a parallel load B
The latest state data value PM3 [1] in the state data supplied from the mold status memory 153 is supplied. The selector 201-0 operates according to the above-described selection signal SEL00.
One of these two status data values is supplied to the register 202-0 at the subsequent stage.

The selectors 201-1 to 201-
201- (n-1) is a B-type status memory 153 corresponding to S10 as two pieces of data, that is, a parallel load.
, And one status data value supplied from a register in the preceding stage as a serial shift. Then, from these two state data, the state data value determined to be the maximum likelihood is supplied to the subsequent register according to the selection signal SEL00. All the selectors 201-0 to 201- (n-1) have the same selection signal SEL.
Therefore, the state data as the sequence of the maximum likelihood state data values selected by the ACS 133 is inherited.

Further, each of the registers 202-0 to 202- (n-
1) updates the held state data value by capturing the supplied state data value according to the clock as described above. Further, as described above, the output of each register is supplied to the status memory corresponding to a state to which a transition can be made after one clock. That is, since the transition can be made to S00 itself, it is supplied to the subsequent selector as a serial shift. The data is supplied to the B-type status memory 152 corresponding to S01 as a parallel load. The state data value VM00 is output from the register 202- (n-1) at the last stage. By outputting state data value VM00 according to the clock, state data is generated as a whole.

The A-type status memory 151 corresponding to the state S11 has the same configuration as the A-type status memory 150. However, the state data PM1 is supplied from the B-type status memory 152 corresponding to S01 as a parallel load corresponding to the state transition S01 → S11 in FIG. Also, the state data PM2 is supplied to the B-type status memory 153 corresponding to S10 as a parallel load corresponding to the state transition S11 → S10 in FIG.

Next, the B-type status memory 152 corresponding to the state S01 will be described with reference to FIG. B
The type status memory does not inherit itself in FIG.
In addition, this corresponds to a state where only one state can transition after one clock. Therefore, no serial shift is performed, and no selector is provided. Therefore, n registers 212-0, 212-1, ... 212
-(n-1) is provided, a clock is supplied to each register, and the operation timing is adjusted.

Each register 212-0, 212-1,... 2
12- (n-1) is supplied with the status data inherited from the A-type status memory 150 corresponding to S00 as PM0 consisting of n-1 status data values. However, '00' is always input to the register 2120 as the first processing stage in synchronization with the clock. This operation corresponds to the fact that the latest state transition that can transit to S01 is always S00, as shown in FIG. Each register 212-0
.About.212- (n-1) updates the held state data value by taking in the supplied state data value according to the clock. In addition, the output of each register performed according to the clock is a state S11 that can transition after one clock as state data PM1 including n-1 state data values.
Is supplied to the A-type status memory 151 corresponding to.
From the final register 212- (n-1), the state data value VM
01 is output. By outputting the state data value VM01 in accordance with the clock, the state data is generated as a whole.

The B-type status memory 153 corresponding to the state S10 has the same configuration as the B-type status memory 152. However, the state data PM2 is supplied from the A-type status memory 151 corresponding to S11 as a parallel load corresponding to the state transition S11 → S10 in FIG. Further, the state data PM3 is supplied to the A-type status memory 150 corresponding to S00 as a parallel load corresponding to the state transition S10 → S00 in FIG. Also,
'11' is always input to the register serving as the first processing stage in synchronization with the clock. This operation corresponds to the state one clock before, which can transit to S10, is S11 as shown in FIG.

By the way, in the Viterbi decoding method, the state data values VM00, V
M11, VM01 and VM10 match each other if the memory length n of the status memory is made sufficiently large. In such a case, any of the state data values generated by the four status memories may be output to the subsequent stage as sm [k + n]. The memory length n is determined in consideration of the C / N of the reproduced signal, frequency characteristics, and the like.

The state data sm [k + n] obtained by the SMU 134 is supplied to the merge block 135. The merge block 135 is implemented by means such as a ROM in FIG.
Is stored. Then, by referring to the decoding matrix, decoded data based on the state data is generated and supplied to the controller 2.
It can be seen from the state transition diagram of FIG. 6 that the decoded data value corresponds to two consecutive state data values. That is, the state data value sm [k + n] generated corresponding to the reproduction signal value z [k] and the state data value generated corresponding to the reproduction signal value z [k−1] one clock before that. sm
Based on [k + n-1], the decoded data value at time point k + n can be determined.

For example, if sm [k + n] is “01” and sm
When [k + n-1] is "00", it is understood from FIG. 6 that "1" corresponds to the decoded data value. Such a correspondence is summarized in the table of the decoding matrix in FIG.

Next, updating of the amplitude reference value by the RAA 136 will be described. As described above, the six amplitude reference values c
The value of 000 to c111 varies depending on various factors. Moreover, since the degree of the fluctuation is not constant, the amplitude reference value cannot be shifted in advance. Therefore, by adaptively controlling the amplitude reference value, the amplitude reference value can follow the distortion and fluctuation of the RF signal, the clock phase error, and the like, thereby improving the accuracy of the calculated value of the branch metric. Can be.

As described above, based on the state data generated by SMU 134 and the reproduced signal value z [k] delayed by shift register 131, RA
A136 performs a calculation for updating the amplitude reference value for each clock. This calculation is performed as follows.

FIG. 6 shows the state data value sm [k + n] generated corresponding to the reproduced signal value z [k] and the state data value sm [k + n-1] generated one clock before the same.
Accordingly, the state transition occurring between these two state data values and the amplitude reference value corresponding to the state transition can be specified. With respect to the amplitude reference value specified in this way, a new amplitude reference value is calculated from the existing value and the reproduction signal value z [k]. In the case of a disk in which an embossed pit area and a magneto-optical area are mixed like a magneto-optical disk, the calculation of the amplitude reference value is performed separately for each area. Therefore, in this case, for the 6-value 4-state Viterbi decoding method, 6 · 2 = 12 amplitude reference values are adapted.

For calculation of the amplitude reference value, sm [k +
n] = '01' and sm [k + n-1] = '11'
This will be described in detail by taking the case of as an example. This is the case where the state transition S01 → S11 in FIG. 6 occurs. FIG. 6 shows that the amplitude reference value corresponding to the state transition is c011. Therefore, RAA136
Performs the calculation for updating the amplitude reference value as follows. c011 (new) = δ · z [k] + (1−δ) · c011 (old) ·· (23)

Generally, when sm [k + n] = pq and sm [k + n−1] = qr, a new value of the amplitude reference value is calculated as follows. cpqr (new) = δ · z [k] + (1−δ) · cpqr (old) ·· (24)

In these equations, δ is a correction coefficient. When setting the value of δ, the relatively continuous characteristics of the recording system and the reproducing system such as the amplitude of the reproduced signal and its fluctuation, distortion such as asymmetry, error in the operation of the waveform equalizer, and the like on the recording medium It is necessary to consider irregular characteristics due to defects and the like. That is, as the value of δ is larger, the amplitude reference value more strongly reflects the amplitude fluctuation of the reproduced signal, the error in the asymmetry and the operation of the waveform equalizer, etc., by the update performed according to the equation (23) or (24). Becomes On the other hand, the amplitude reference value is easily affected by an irregular signal such as a defect caused by a defect or the like on the recording medium. On the other hand, when the value of δ is reduced, the amplitude reference value is less likely to be affected by irregular signals such as defects, but on the other hand, the amplitude reference value follows the reproduced signal more slowly.
The effect of the adaptation of the amplitude reference value by the update made according to 3) or (24) is reduced.

According to the above equations (23) and (24), RA
At A16, a new amplitude reference value is calculated and supplied to the BMC 132. As understood from the above description, for example, in the case of Viterbi decoding of 6 values and 4 states, the amplitude reference values to be adapted are c000, c001, c011, and c1.
00, c110, and c111. The amplitude reference value is adaptively changed according to various factors such as a recording situation and defocus, so that the influence of various factors can be absorbed.

FIG. 12 shows states sm [k + n-1] and sm
A list summarizing which amplitude reference value is updated for [k + n] is shown. For example, state data sm [k + n-
1] is '00' and the state data sm [k + n] is '00'
, That is, when the state transits from state S00 to S00,
The amplitude reference value c000 is updated. Further, when the state transits from the state S00 to S01, the amplitude reference value c001 is updated. In addition, as shown in FIG. 12, the specific amplitude reference value is updated according to the state transition.

[0092] 2. 2. Disk Drive Device (I) of Embodiment 2-1 Configuration of Disk Drive Device As an example employing the Viterbi decoding method described above,
A disk drive device according to an embodiment of the present invention will be described. In addition, this disk drive device
Perforated WORM disk, phase change WO
RM disk, magneto-optical disk (MO disk), phase change type rewritable disk (DVD-RAM, DVD
-RW or the like). That is, the present invention is suitable for a drive device for a disc having a correlation between the recording laser power and the asymmetry of the reproduced RF signal. A specific example will be described as a disk drive device corresponding to a hole type WORM disk.

FIG. 13 shows the structure of the disk drive of this embodiment. The same functional portions as those described in FIG. 1 are denoted by the same reference numerals, and redundant detailed description thereof will be omitted. Further, this block diagram mainly shows a processing system for a recording / reproducing signal, and there are some other parts omitted from the servo system.

The recording / reproducing of information is performed by the operation of the optical pickup 7 while the disk 6 (a hole-type WORM disk) serving as a recording medium is driven to rotate by a spindle motor 9 in a drive device. The position control (seek, tracking servo, thread servo) of the optical pickup 7 during recording / reproduction, the focus servo of the laser beam from the optical pickup 7, and the rotation servo of the spindle motor 9 are performed by a servo system (not shown). Will be.

A drive controller (hereinafter, referred to as a controller) 2 serves as a master controller of the drive device and controls various operations and communicates with the host computer 1. That is, the controller 2 controls the operation of recording the supplied data on the disk 6 in response to the recording instruction from the host computer 1, and also reads the requested data from the disk 6 in response to the instruction from the host computer 1. Control of the transfer to the host computer 1.
The controller 2 also has a function of encoding and decoding data.

The CPU 3 is a part that controls each part for a recording / reproducing operation based on an instruction from the controller 2. For example, it performs various controls on the RF block 20 of the reproduction system, and gives instructions to the DSP 17 functioning as a servo processor.

At the time of recording, the controller 2 receives user data to be recorded in accordance with a command from the host computer 1 and encodes the data based on the user data as information words, for example, RLL (1,
7) Generate a code. This code word is recorded data WDAT
A is supplied to the LPC 4. Further, the controller 2 instructs the LPC 4 as a WGATE signal on the light emission operation in the recording mode and its timing. Further, a recording clock WCLK serving as a reference for the recording processing operation is generated, and LP
Supply to C4.

The LPC 4 and the APC 10 cause the laser output from the optical pickup 7 to be executed in accordance with the recording data WDATA and WGATE signals as described with reference to FIG. During playback,
The laser output level at each time of recording, ie, LP
The drive pulse value of the laser output from C4 is DSP1
7 (CPU 3). Therefore, the controller 2 can change the recording laser power and the reproduction laser power by instructing the CPU 3.

At the time of reproduction (at the time of normal reproduction and at the time of data reading for the verify operation at the time of write and verify)
, The following operation is performed under the control of the controller 2 and the CPU 3.

The controller 2 outputs the RGATE signal to the LPC
4 and the RF block 20 to control the reproduction operation. That is, the controller 2 uses the RGATE signal to
While instructing C4 to continuously emit light using the laser power as a reproduction level, the RF block 20 is also instructed to perform a reproduction process.

At the time of reproduction, first, LPC4 sets RGAT
A laser drive pulse is generated according to the E signal, and a laser output for a reproducing operation is executed from the optical pickup 7. The optical pickup 7 irradiates the magneto-optical disk 6 with laser light, and receives reflected light generated thereby. Further, various signals are generated by arithmetic processing of signals according to the amount of reflected light. That is, it includes a reproduced RF signal, a focus error signal (not shown), a tracking error signal, and the like.

The reproduced RF signal is supplied to the filter unit 11 after the gain is adjusted by the variable gain amplifier 8 in the RF block 20. The gain setting in the variable gain amplifier 8 is performed by a control signal GS1 from the CPU 3. For example, the gain setting is changed according to the RF signal level that varies depending on the type and characteristics of the disk so that an RF signal optimal for reproduction signal processing is obtained. Although not shown, the focus error signal and the tracking error signal are supplied to the DSP 17 and used for controlling the servo system by the DSP 17. The filter unit 11 includes an RF effective band boost circuit,
It is composed of a low-pass filter that performs noise cut and a waveform equalizer that performs waveform equalization. The input signal is equalized so that a partial response characteristic suitable for the Viterbi decoding method performed by the Viterbi decoder 13 is obtained. The A / D converter 12 is a PL
A / D conversion is performed according to the reproduction clock DCK from the L unit 14, and a reproduction signal value z [k] is output. The Viterbi decoder 13 outputs a reproduced signal value z according to the reproduced clock DCK.
Based on [k], the decoded data DD is generated by the Viterbi decoding method. The configuration and operation in the RF block 20 and the configuration and operation of each unit such as the BMC 132 in the Viterbi decoder 13 are the same as those described with reference to FIG.

However, for the RAA 136, the amplitude reference values c000 to c111 calculated for updating are
, And can be used for calculation of asymmetry as described later.

The decoded data DD decoded by the Viterbi decoder 13 is supplied to the controller 2. The controller 2 reproduces user data and the like by performing decoding processing corresponding to encoding such as channel encoding on the decoded data DD. For example, (1-7) RLL decoding processing, ECC decoding processing (error correction processing), and the like are performed.

As will be described later in detail, at the time of recording, the controller 2 controls the write and verify operation to be executed as a recording operation on a certain sector of the disk 6. Various settings such as read conditions during verification,
The controller 2 also executes verification OK / NG determination, control of a retry action, and the like.

2-2 Relationship between Recording Laser Power and Asymmetry When data is recorded on the disk 6 by an optical modulation method such as a WORM disk or a magneto-optical disk, the size of a mark (pit) recorded on the disk is determined by the recording. It greatly depends on the value of the laser power, and this greatly affects the waveform of the reproduced RF signal. The recording laser power is equal to the reproduction R
How the F signal is affected will be described using an impulse response as an example.

FIG. 14 shows the relationship between the magnitude of the recording laser power and the impulse response of the reproduced RF signal. Note that this is an example of a PR (1, 2, 1) partial response response. When the recording laser power is at the optimum value, the impulse response becomes as shown by a curve (b) in FIG. At this time, the amplitude ratio at three time points k−1, k, and k + 1 as the sampling time points of the A / D conversion is 1: 2:
It becomes 1.

However, when the recording laser power is increased,
Since the recording mark on the disk becomes large, the impulse response becomes as shown by the curve (a), that is, the pulse width becomes large. Therefore, the amplitudes at the sampling times k−1 and k + 1 are larger than half the peak value. On the other hand, when the recording laser power decreases, the recording mark on the disk becomes smaller, so that the impulse response becomes as shown by the curve (c), that is, the pulse width becomes narrower. Therefore, the amplitudes at the sampling times k−1 and k + 1 are smaller than half the peak value.

An eye pattern for an actual reproduced RF signal can be represented by superposition of impulse responses at an arbitrary time point k. FIG. 15 shows the degree of eye opening of the eye pattern due to the difference in recording laser power. FIG.
(B) shows an eye pattern in a state where the recording laser power is optimal, and the eyes are vertically symmetric. On the other hand, when the recording laser power is large and small, the eye is shifted upward or downward as shown in FIGS. 15A and 15C, respectively. This FIG.
The state in which the eye is opened asymmetrically due to the non-optimal recording laser power as in (a) and (b) is called asymmetry. That is, the asymmetry is an asymmetric distortion generated in the reproduction RF signal waveform due to an excess or deficiency of the recording laser power.

In order to quantitatively express the asymmetry, the asymmetry value is defined as γasy and is defined as follows. γasy = (center voltage of 2T envelope−center voltage of 8T envelope) / (peak-to-peak voltage of 8T envelope) (25)

FIGS. 16A and 16B show a signal waveform of a 2T pattern and a signal waveform of an 8T pattern. When the waveform equalization process is performed on the reproduced RF signal corresponding to the 2T pattern, FIG.
As shown in FIG. 6A, the amplitude reference values c001, c01
The waveform has a waveform in which 1, c110, and c100 are periodically repeated. When the waveform equalization process is performed on the reproduced RF signal corresponding to the 8T pattern, as shown in the figure, the amplitude reference value c00
0, c000, c000, c000, c000, c00
0, c001, c011, c111, c111, c11
1, c111, c111, c111, c110, c10
0 and c001 are periodically repeated.

FIG. 17 shows the waveforms of the 2T pattern and the 8T pattern together. FIG. 17 visually shows the asymmetry value γasy. Based on FIG. 17 and the above equation 25, the asymmetry value γ is obtained for each eye pattern shown in FIG.
It can be seen that asy is as follows. When the recording laser power is too large: γasy> 0 When the recording laser power is optimal: γasy = 0 When the recording laser power is too small: γasy <0

As described above, it is possible to estimate the value of the recording laser power from the asymmetry value γasy. Therefore, if the recording laser power is set so that the asymmetry value γasy falls within a certain range,
That will be the proper recording laser power.

According to the above equation (25), the reproduction R
To calculate the asymmetry value γasy of the F signal, “2
It is necessary to detect the center voltage of the T envelope, the center voltage of the 8T envelope, and the peak-to-peak voltage of the 8T envelope, respectively. Here, FIG.
6. As can be seen from FIG. 17, these values can be calculated from the amplitude reference values in the Viterbi decoder 13. That is,
The “center voltage of the 2T envelope” is the amplitude reference value c00
It can be obtained as an average value of 1, c011, c110, and c100. Also, "center voltage of 8T envelope"
Can be obtained as an average value of the amplitude reference values c000 and c111. Further, “peak-to-peak voltage of the 8T envelope” can be obtained as a difference between the amplitude reference values c000 and c111. Therefore, when the amplitude reference value is applied to the above equation (25), γasy = ((c001 + c011 + c110 + c100) / 4− (c000 + c111) / 2) / (c111−c000) (26) ).

As described above, the amplitude reference values c000 to c1
11 are adapted in the RAA 136 in the Viterbi decoder 13 and updated in the BMC 132. Assuming that the amplitude reference value is adapted in this way, if the reproduced RF signal has asymmetry, each amplitude reference value follows that. Therefore, FIG.
The CPU 3 (or the controller 2) of the above can use the amplitude reference value calculated by the RAA 136 to calculate the above equation (26) to know the value of the recording laser power for the reproduced RF signal at that time. it can.

Next, it is considered what range the asymmetry value γasy falls within and the recording laser power is appropriate. FIG. 18A shows the recording laser power (Write Po
wer) shows the characteristics of the byte error rate (BER). Here, is the characteristic when the Viterbi decoding method is adopted, and is the characteristic when the bit-by-bit method is adopted.

As can be seen from this figure, in the A region where the recording laser power is low (P1 or less), the error rate is high in both the Viterbi decoding method and the bit-by-bit method. That is, when the recording laser power is equal to or less than P1,
It can be said that the power is too small. Further, even in the D region where the recording laser power is high (P3 or more), the error rate is high in any of the Viterbi decoding method and the bit-by-bit method. That is, when the recording laser power is P3 or more,
It can be said that the power is excessive. Recording laser power is P2
The error rate is low in any of the decoding schemes in the C area which is in the range of ~ P3. That is, the range of P2 to P3 can be said to be a suitable recording laser power. Recording laser power is P1
In the area B in the range of P2, the error rate is low in the case of the Viterbi decoding method. That is, the range of P1 to P3 can be said to be a suitable recording laser power for the drive device of the Viterbi decoding system. However, in the B region, the bit-by-bit method has a high error rate. That is, for a drive device of the bit-by-bit decoding system, P1
The range from P2 to P2 is not an appropriate recording laser power.
From the above, the recording laser power is P in any of the Viterbi decoding method and the bit-by-bit decoding method.
If it is in the range of 2 to P3, it is OK.

FIG. 18B shows the asymmetry value of the reproduced RF signal corresponding to FIG. 18A. Thus, the asymmetry value is proportional to the recording laser power. The optimum recording laser power range is P2
Assuming that it is ＰP3, the asymmetry value γasy should be γasy2 <γasy <γasy3 (27). That is, for example, at the time of write and verify, if the asymmetry value γasy calculated by the above equation (26) is within the range of the above equation (27), the recording laser power may be determined to be an appropriate value.

2-3 Write-and-Verify Processing As described above, it is possible to determine whether the recording laser power is appropriate from the asymmetry value γasy of the reproduced RF signal. In this example, data recording on the disk 6 is performed. Verification (write-and-verify operation) at the time, but the asymmetry value γasy
To determine whether the recording laser power is appropriate. The processing at the time of write and verify of this example will be described with reference to FIG.

When data recording is instructed from the host computer 1 and user data to be recorded is transferred, the controller 2 starts control of recording the user data on the disk 6. That is, as described above, WG
The ATE signal and the recording clock WCLK are transmitted to each unit, and the recording data transferred from the host computer 1 is encoded, and the recording data W is transmitted.
Supply it to LPC4 as DATA. The recording operation is executed.

Although the recording operation is performed in units of sectors, the recording confirmation operation by reading immediately after recording, that is, the verify operation, may be performed for all recorded sectors, or may be performed only for some sectors. May be. The write-and-verify processing in FIG. 19 is shown as a processing at the time of a recording operation for a sector to be verified (write-and-verify processing for one sector recording).

As the recording operation processing of one sector,
First, at Step F101, the controller 2 sets the recording laser power to an initial value. And step F1
In step 02, the operation of each required unit is executed by the above-described various controls, and operation control for recording user data in a certain sector on the disk 6 is performed.

When the recording operation on the sector in step F102 is completed, the process proceeds from step F103 to the verify operation. First, in step F103, the ECC criteria and the resync criteria are set to stricter values than usual. That is, a setting change for making read conditions (verification OK conditions) strict at the time of verification. Then, as an actual verify operation in step F104, data is read from the sector in which the data was recorded in step F102.

In step F104, it is determined whether or not the data reading has been properly completed, that is, whether or not a state satisfying the read conditions at the time of verification has been obtained for the synchronization processing, the ECC processing, and the decoding. Here, the case where the reading is OK is a case where it can be determined that there is no large defect in the sector. On the other hand, in the case of reading NG, since the read conditions are set strictly, there is a possibility that there is a defect which affects the reproduction operation, taking into account even a drive device having a low reproduction capability. Is high.

If reading is OK in step F105, the process proceeds to step F106. Then, the asymmetry value γasy is calculated by the CPU 3, and it is determined in step F107 whether the asymmetry value γasy is a value within a predetermined range. The asymmetry value γasy is calculated by the CPU
3 takes in the amplitude reference value updated by the RAA 136 at the time of data reading, and performs the calculation by the above equation (26). Also, within the predetermined range is the range of the above equation (27),
That is, the calculated asymmetry value γasy becomes γasy
It is sufficient that 2 <γasy <γasy3 is satisfied.
This means that the recording laser power is within the area C in FIG. In other words, the recording laser power is within a range where the reading can be properly performed not only by the drive device using the Viterbi decoding method as in this example, but also by the drive device using the bit-by-bit decoding method having relatively low readability.

In step F107, the asymmetry value γas
If it is determined that y is within the predetermined range, step F10
It can be determined that the laser power was appropriate for the recording operation performed in step 2. Therefore, the verification is OK by this, and the read condition (E
(CC criteria, resync criteria) are returned to normal values, the retry counter RC indicating the number of retries is cleared in step F109, and the write and verify processing for the sector is normally terminated.

On the other hand, if the reading is NG in step F105, or if it is determined in step F107 that the asymmetry value γasy is not within the predetermined range even if the reading is OK in step F105, the verification becomes NG,
Move on to write and verify retry processing.

First, if the reading is NG in step F105, the flow advances to step F112 after checking the value of the retry counter RC in step F110, and the position of the optical pickup 7 is moved to another sector. This is because a write-once disc cannot rewrite a sector on which recording has already been performed. That is, this is a process for setting a replacement sector for the sector on which recording has been performed in step F102 and performing recording as a retry operation on the replacement sector. Next, in step F113, the retry counter RC is incremented. At the time of the first retry, the retry counter RC = 1. After checking the value of the retry counter RC in step F114, the process returns to step F102, and data is recorded in the sector (that is, the replacement sector). That is, as described above, when the process proceeds from the step F105 at the time of the first retry operation, it is determined that there is a high possibility that a defect exists in the sector where the recording was performed, and the recording retry is performed in another sector without changing the recording laser power. Will be done. In the case of a rewritable disk such as a magneto-optical disk, recording retry can be performed on the same sector as the first one. However, when there is a high possibility of a defect, it is preferable to change the sector to be recorded.

After such recording retry is performed, the verification is performed in the same manner in the processing from step F103. If the verification is OK in the processing in steps F105 to F107, the recording of the sector is normal. Will be terminated. However, reading NG is again performed in step F105.
In the case of, a retry is performed in the same manner. However, an upper limit number of such retries (that is, a retry executed without changing the laser power because it is determined that the possibility of a defect is high) is set as x times in step F110. That is, even if the above retry is performed several times, if the result is still NG in step F105, the defect is not a defect (if the read is also NG even if the sector is moved and recorded, it is very unlikely that the defect is caused by the defect). It is determined that there is a high possibility that there is a problem with the recording laser power.

Therefore, when it is determined in step F110 that the retry counter RC ≧ x, that is, when the x retries have already been performed and the (x + 1) th retry is started, the asymmetry value γ is given to the CPU 3 in step F115.
asy is calculated, and in a step F116, it is determined whether or not the asymmetry value γasy is within a predetermined range. This is the same processing as steps F106 and F107 described above. Here, if the asymmetry value γasy is within the predetermined range, there is no problem with the recording laser power, so the process proceeds to step F112, and the retry is performed in the same manner as described above without changing the recording laser power. Going on. In such a case, a retry may be performed by changing another recording condition.

On the other hand, when it is determined in step F116 that the asymmetry value γasy is not within the predetermined range, or in step F105, the reading is OK, but in step F1
If it is determined in step 07 that the asymmetry value γasy is not within the predetermined range and the processing shifts to the retry processing, step F11
Proceed to 1 to perform calibration (change) of the recording laser power. This is the calculated asymmetry value γas
This is processing for raising and lowering the recording laser power according to y. For example, if the asymmetry value γasy is equal to or less than γasy2, the recording laser power is insufficient, and the recording laser power is reset to a higher value. At this time, γasy
An appropriate increase width may be calculated and reset according to the value of 2-γasy. In addition, the calculated asymmetry value γas
If y is equal to or more than γasy3, the recording laser power is excessive, and the recording laser power is reset to a lower value. Of course, an appropriate reduction width may be calculated and reset according to the value of γasy−γasy3.

As calibration, for example, a test write of a specific data pattern is performed in a predetermined area on the disk, and the test write is performed to reproduce the asymmetry value γasy.
, An appropriate recording laser power may be searched for. This process is particularly useful if the disk 6 is a rewritable magneto-optical disk or the like. Even with the write-once disc 6, such trial writing is possible, but sector consumption is increased.
It may be determined whether or not to execute the test writing according to the situation. For example, it is conceivable to perform trial writing if there is enough remaining area for trial writing.

After resetting the recording laser power in step F111, steps F112, F113, F114,
Proceeding to F102, a recording retry is performed.

As described above, the retry is repeated one or more times. However, the upper limit number y is set as the number of retry processes, and the retry number is checked in step F114, so that When the retry is performed, the process does not proceed to the next retry (step F1).
14 when RC> y). In this case, the verification is not successful even after the retry has been performed an upper limit number of times, so that the processing ends with an error. In this case, the controller 2 reports an error end to the host computer 1 for the sector recording operation.

By the above-described write and verify processing, the reliability of the verify operation becomes high, and for example, a write and verify operation sufficiently considering a drive device having a low read capability is realized. That is, first, as the conditions for verifying OK, both the condition that reading is OK after strict read conditions and the condition that the recording laser power is within an appropriate range by the asymmetry value γasy must be satisfied. In other words, even if the drive device has a low read capability, the drive cannot be read due to the defect,
If both the drive power of the read device is low and the proper recording laser power is satisfied, the verification is OK. Therefore, a recording operation with sufficient reproduction compatibility is realized.

If the reading becomes NG at the time of the verification, the influence of the defect is considered. Therefore, by performing the retry without changing the recording laser power, an appropriate retry operation is performed. Further, when the asymmetry value γasy is determined not to be within the predetermined range at the time of the verification, the recording laser power is changed and the retry is performed, so that an appropriate retry operation is performed. In addition, when the recording laser power is not actually appropriate, the retry operation can lead to the completion of the appropriate recording operation.

As the write-and-verify processing, various modifications other than the processing procedure of FIG. 19 can be considered. For example, when the data reading becomes NG for the first time, the asymmetry value γasy is calculated before starting the retry to determine whether the recording laser power is appropriate, and it is determined whether the recording laser power should be changed at the time of the retry. Is also good.

2-4 Example of Operation Mode of Write-and-Verify Write-and-verify for sector recording is executed as described above, but actually, a plurality of operations are performed by one recording operation (recording instruction from the host computer 1). Sectors are often recorded. At this time, the write-and-verify processing may be performed on all sectors, or the write-and-verify processing may be performed on only some sectors (recording is not performed on other sectors and verify is not performed).

When the write and verify is performed for all the sectors, for example, the process of FIG. 19 is executed for each sector. On the other hand, when verifying is performed only on a part of the sectors, for example, the write-and-verify is performed only on the first sector of a series of continuously recorded sectors, or the write-and-verify is performed only on the last sector. Verification may be performed. Alternatively, write and verify may be performed every several sectors.

When verifying is performed only on the first sector, it is first determined whether or not the recording laser power is appropriate for a series of recording operations to be performed, and if it is not appropriate, the power can be changed. In the sector recording, the recording laser power can be kept at an appropriate value. When verifying is performed only on the last sector, a series of recording operations are performed, and then verification of the last sector is performed to detect whether or not recording is OK.
If this is the case, the data reliability is reduced for all of the series of sectors, but there is an advantage that the processing is time-efficient.

The host computer 1 may instruct how to execute the write-and-verify among them, depending on the degree of reliability and data type required for the recording data, or the drive device. May be fixed according to the specifications and the use environment, or may be selectable by the user. For example, when data reliability is required to a high degree, write and verify is performed for all sectors, but when not so required, only some sectors may be considered.

As a method of calculating the asymmetry value γasy, if the Viterbi decoding method is employed as in this example, the amplitude reference value may be used as described above, but the asymmetry value is obtained by using the envelope of the RF signal. It is also possible to perform sampling and use the sampled value. That is, the asymmetry value γasy can be calculated by collecting the sampling values required for the calculation of the above equation (25), so that the present invention can be applied to a drive device that does not employ Viterbi decoding.

It is needless to say that the operation of this embodiment can be widely applied as a drive device for a medium having a correlation between the recording laser power and the asymmetry value.

[0144] 3. 3. Disk Drive Device (II) of Embodiment 3-1 Relationship between Recording Laser Power and Amplitude The write-and-verify operation of the disk drive device (I) described above, particularly the operation of determining whether or not the recording laser power is appropriate, is performed by the recording laser. This is suitable for a disc having a correlation between the power and the asymmetry value.
However, for example, among WORM disks, there is no correlation between the recording laser power and the asymmetry value for the type of disk called an alloy type.

In this alloy type WORM disk, in the unrecorded state, a multilayer film is melted and mixed by the heat of the laser at the time of recording, and becomes an alloy at the time of cooling to increase the reflectivity. Is formed. In this alloy type, the asymmetry value hardly changes even if the recording laser power is increased or decreased. Therefore, the recording laser power cannot be estimated from the asymmetry value as described in the above example. However, in the case of an alloy type WORM disk, the RF amplitude of the reproduced RF signal increases as the recording power increases. This is due to the difference in the thermal diffusion of the disk during recording.

Therefore, in the disk drive device (II) of this embodiment, the reproduction RF is used instead of the asymmetry value.
The amplitude value of the signal is obtained, the recording laser power is estimated from the signal, and the estimated power is used as the verify condition.

The configuration of the disk drive of this embodiment corresponding to the alloy type WORM disk is the same as that shown in FIG. In this example, the CPU 3 can calculate the amplitude value using the amplitude reference value calculated by the RAA 136.

By the way, the amplitude value differs from the asymmetry value and depends not only on the recording power but also on the settings of the variable gain amplifier 8 and the filter section 11 of the RF block 20. The following method is used to eliminate this effect.
First, a predetermined pattern is recorded in a certain area on a disk using a drive (reference drive) whose recording power is completely grasped in advance. This reference recording area is set as a manufacturer test area (manufacturers zone) in the disc format standard. Or,
At the time of formatting the disk, a DDS area in which the type of the disk, the address of the spare area, and the like are recorded may be recorded by the reference drive and used as a reference recording area.

When the disk is inserted into the drive during normal use and started up, the drive first reads the reference recording area. Then, the setting of the gain amplifier is adjusted so that the amplitude of the reproduced RF signal when the data recorded therein is read becomes a certain value (reference value). That is, the amplitude obtained by reading the reference recording area (obtained by Expression (28) or Expression (29) described later) is:
If it is smaller than the reference value, the gain of the gain amplifier is increased, and if it is larger, the gain of the gain amplifier is reduced.
Then, the reference recording area is read again to check whether the amplitude becomes the reference value. This is repeated until the amplitude reaches the reference value.

Thus, a reproduction signal recorded with a certain laser power is reproduced with the same amplitude in the drive.
This amplitude value is called a reference amplitude value. In this case, if the amplitude value of the reproduced RF signal is larger than the reference amplitude value, the laser power when recording the sector there is larger than the reference laser power, and if the amplitude value of the reproduced RF signal is smaller than the reference amplitude value. It can be seen that the laser power when recording the sector there is lower than the reference laser power.

In the verify operation of this embodiment, similarly to the above example, a sector having a large defect is verified by a verify operation.
In order to achieve G, the rigging criteria and ECC criteria will be tightened. Further, the amplitude value of the reproduced RF signal is used for evaluating the validity of the recording laser power. By doing so, similar to the above example, at the time of verify NG, whether verify NG caused by a large defect
It is possible to clearly determine whether the verification NG is caused by the recording laser power.

The method of calculating the amplitude value is as follows. The amplitude of the reproduced RF signal can be obtained from the adapted six amplitude reference values. FIG. 20 shows a 2T pattern (minimum amplitude pattern) and an 8T pattern (not necessarily 8
Although there is a case where the amplitude is not T, the maximum amplitude pattern is shown. However, in PR (1, 2, 1), since the six amplitude reference values change as shown in FIG.
Is given by AMP = c111−c000 Expression (28) Further, instead of the amplitude of the reproduction RF signal, the amplitude VFO of the 2T pattern corresponding to the size of the opening of the eye pattern can be used for estimating the recording laser power. In this case, the amplitude VFO is given by VFO = ((c011 + c110)-(c001 + c100)) / 2 (29)

Therefore, the CPU 3 (controller 2)
By taking in the amplitude reference value updated by the RAA 136, the amplitude value (AMP or VFO) can be calculated. Then, the controller 2 can know the value of the recording laser power for the reproduced RF signal at that time from the calculated amplitude value.

Consider what range the amplitude value AMP (similarly for VFO) falls within the range and the appropriate recording laser power. FIGS. 21A and 21B show the relationship between the byte error rate (BER) with respect to the recording laser power (Write Power), the recording laser power, and the amplitude value, similarly to FIG. As described with reference to FIG.
The area, that is, the recording laser powers P2 to P3 are within an appropriate range. Therefore, it is sufficient that the amplitude value AMP satisfies AMP2 <AMP <AMP3 (30). That is, for example, at the time of write and verify, if the amplitude value AMP calculated by the above equation (28) is within the range of the above equation (30), the recording laser power may be determined to be an appropriate value.

3-2 Example of Write-and-Verify Processing and Operation Mode The write-and-verify processing in this example is shown in FIG. FIG. 22 shows a write-and-verify process for one sector recording similarly to FIG.
Steps F201 to F205 and F208 to F208
Step 214 is similar to steps F101 to F105 and steps F108 to F114 in FIG. In this case, step F
206, F207 (and steps F215, F216)
Is different from the above example in that the amplitude value is calculated to determine whether the recording laser power is appropriate.

That is, if the reading is OK in step F205 and the process proceeds to step F206, or if the process proceeds to step F215 when performing x or more retries, the controller 2 causes the CPU 3 to calculate the amplitude value (AMP or VFO), and then proceeds to step F207. Alternatively, in a step F216, it is determined whether or not the amplitude value is within a predetermined range.

If it is determined that the amplitude value is within the predetermined range, it can be determined that the laser power is appropriate for the recording operation performed in step F202. Therefore, in the case of step F207, it is determined that the verification is OK. On the other hand, in the case of step F216, the next retry action is performed without changing the recording laser power. Also,
If it is determined that the amplitude value is not within the predetermined range, the laser power is inappropriate, and a retry action is performed after calibrating (changing) the recording laser power in step F211.

By the write-and-verify processing as shown in FIG. 22, the same effect as in FIG. 19 can be obtained. Therefore, even for an alloy type WORM disc having no correlation between the recording laser power and the asymmetry value,
It is possible to improve the reliability of the write and verify operation and maintain the reproduction compatibility. As the write-and-verify processing, various modifications other than the processing procedure of FIG. 22 are conceivable. For example, when data reading becomes NG for the first time, an amplitude value may be calculated before retrying to determine whether the recording laser power is appropriate or not, and whether the recording laser power should be changed at the time of retrying may be determined. Good.

The write-and-verify process for sector recording is performed as described above. The write-and-verify process may be performed for all sectors at the time of recording, or may be performed for only some sectors. May be performed. This is as described in the example of FIG.

As a method of calculating the amplitude value, if the Viterbi decoding method is employed as in this example, the amplitude reference value may be used as described above, but the amplitude value is obtained by sampling the envelope of the RF signal. It is also possible to use the sampling value. That is, by detecting the peak and the bottom of the RF signal amplitude, the calculation corresponding to the above equation (28) can be performed. Therefore, the present invention is applicable to a drive device that does not employ Viterbi decoding. In addition,
The operation of the present example can be widely applied not only to an alloy type WORM disk but also to a drive device for a medium having a correlation between a recording laser power and an amplitude value.

[0161]

As can be understood from the above description, the drive device of the present invention can obtain the following effects. According to the present invention, the asymmetry value for the data signal waveform, or whether or not the laser power at the time of recording is appropriate according to whether the amplitude value is within a predetermined range is clearly determined,
It is possible to determine whether or not a recording error has occurred.
As a result, when it is determined that the laser power at the time of recording is not appropriate, the recording laser power can be adjusted and the retry of the recording operation can be executed. That is, if the error is caused by the recording laser power at the time of verification or the like, it can be clearly determined, and in that case, the recording laser power can be changed and an appropriate retry operation can be performed. As a result, the reliability of the write-and-verify operation and the recording operation performance can be improved.

When a decoding error (read NG) occurs in the decoding means, that is, when there is a high possibility that an error has occurred due to the influence of a defect or the like, the recording operation and the reading operation are performed without changing the recording laser power. By performing the retry, an appropriate retry operation is performed. On the other hand, if the decoding error remains even after the retry operation is performed a predetermined number of times, that is, if there is a high possibility that the error is not due to a defect, the recording time depends on whether the asymmetry value or the amplitude value is within a predetermined range. By judging whether or not the laser power is appropriate, it is possible to judge whether the recording laser power is appropriate. If it is determined that the laser power at the time of recording is not appropriate, the recording laser power is adjusted and a retry of the recording operation is performed, so that an appropriate retry is performed and an error caused by the recording laser power is performed. In the case of (1), it is possible to guide the completion of an appropriate recording operation by the retry operation. Therefore,
If the recording laser power can be changed and the recording can be made OK, it is possible to accurately judge it and lead to the completion of proper recording and not end the error, so that the recording operation performance is improved. .

Further, according to the present invention, even when decoding is successful by the decoding means, whether or not the laser power at the time of recording is appropriate depends on whether or not the asymmetry value or the amplitude value is within a predetermined range. Is determined, and when it is determined that the laser power at the time of recording is not appropriate, the recording laser power is adjusted to retry the recording operation. Therefore, when data can be reproduced when verification NG should be originally performed, for example, when the read capability of the drive device is high and the data can be read even if the recording laser power is inappropriate, In other words, the retry of the recording operation is executed, so that even a drive device having a low read capability can be properly reproduced. That is, a recording operation capable of maintaining reproduction compatibility is realized.

[Brief description of the drawings]

FIG. 1 is a block diagram of a general disk drive device using Viterbi decoding to which the present invention can be applied.

FIG. 2 is an explanatory diagram of an outline of a mark position recording method and a mark edge recording method.

FIG. 3 is an explanatory diagram of a minimum magnetization reversal width in an RLL (1, 7) encoding method.

FIG. 4 shows a reproduction signal of data recorded by an RLL (1, 7) code and a mark edge recording method in PR (1, 2, 2,
FIG. 4 is an explanatory diagram of an eye pattern when the waveform is equalized in 1).

FIG. 5 is an explanatory diagram of a state transition process of a Viterbi decoding method.

FIG. 6 is an explanatory diagram of a state transition of the Viterbi decoding method.

FIG. 7 is an explanatory diagram of a trellis diagram of state transition of the Viterbi decoding method.

FIG. 8 is a block diagram of the SMU of the Viterbi decoder.

FIG. 9 is a block diagram of an A-type status memory of the SMU of the Viterbi decoder.

FIG. 10 is a block diagram of a B-type status memory of the SMU of the Viterbi decoder.

FIG. 11 is an explanatory diagram of an operation of selecting a state data value in a merge block of the Viterbi decoder.

FIG. 12 is an explanatory diagram of an amplitude reference value adapted by a Viterbi decoder.

FIG. 13 is a block diagram of the drive device according to the embodiment.

FIG. 14 is an explanatory diagram of a relationship between a recording laser power and an impulse response.

FIG. 15 is an explanatory diagram of a relationship between a recording laser power and an eye pattern.

FIG. 16 is an explanatory diagram of envelopes of 2T and 8T patterns.

FIG. 17 is an explanatory diagram of asymmetry values observed in envelopes of 2T and 8T patterns.

FIG. 18 is an explanatory diagram of an appropriate asymmetry value range in the embodiment.

FIG. 19 is a flowchart of a write and verify operation of the embodiment.

FIG. 20 is an explanatory diagram of amplitude values of 2T and 8T patterns.

FIG. 21 is an explanatory diagram of an appropriate amplitude value range in the embodiment.

FIG. 22 is a flowchart of a write and verify operation of the embodiment. It is.

[Explanation of symbols]

1 host computer, 2 drive controller,
3 CPU, 4 LPC, 5 magnetic head, 6 disk, 7 optical pickup, 8 amplifier, 9 spindle motor, 10 APC, 11 filter section, 12 A /
D converter, 13 Viterbi decoder, 14 PLL unit, 131
Shift register, 132 BMC, 133 ACS,
134 SMU, 135 merge block, 136 R
AA

Claims (10)

[Claims] 1. A head unit capable of recording data on a recording medium by irradiating a laser beam and reading a recorded data signal, and a decoding process for the data signal read by the head unit Decoding means for obtaining reproduction data, asymmetry calculation means for calculating an asymmetry value for a data signal waveform read by the head means, and supplying recording data to the head means and providing data to a recording medium. After the recording of the data, the reading of the data signal for the recorded data is executed, and the recording is performed based on whether or not the asymmetry value calculated by the asymmetry calculating means for the data signal waveform is within a predetermined range. Discriminates whether or not the laser power is appropriate, and the laser power during recording is not appropriate. And a control means for determining a recording operation error when it is determined that the drive operation has been completed. 2. When the control means determines that the laser power at the time of recording is not appropriate and determines that a recording operation error has occurred,
2. The drive device according to claim 1, wherein a retry of a recording operation and a reading operation is performed by changing a recording laser power. 3. When the control means supplies recording data to the head means to execute writing of data on a recording medium, and then executes reading of a data signal for the recorded data. 2. The drive device according to claim 1, wherein when a decoding error occurs in the decoding unit, a retry of a recording operation and a reading operation is performed without changing a recording laser power. 4. The asymmetry calculating means calculates the asymmetry when the decoding error remains even after the recording operation and the reading operation are retried a predetermined number of times without changing the recording laser power. It is determined whether the laser power at the time of recording is appropriate based on whether the asymmetry value is within a predetermined range.If the laser power at the time of recording is determined to be inappropriate, the recording laser power is changed. 4. The drive device according to claim 3, wherein a retry of the recording operation is executed by performing the retry. 5. When the control means supplies recording data to the head means to execute writing of data to a recording medium, and then executes reading of a data signal for the recorded data. If the decoding is OK in the decoding unit, it is determined whether the laser power at the time of recording is appropriate based on whether the asymmetry value calculated by the asymmetry calculation unit is within a predetermined range, 2. The drive device according to claim 1, wherein when it is determined that the laser power at the time of recording is not appropriate, the recording laser power is changed to retry the recording operation. 6. Head means capable of recording data on a recording medium by irradiating a laser beam and reading recorded data signals, and decoding processing of the data signals read by said head means Decoding means for obtaining reproduction data; amplitude calculating means for calculating an amplitude value of a data signal waveform read by the head means; and recording data for supplying recording data to the head means. After the recording of the data signal is performed, the reading of the data signal for the recorded data is performed, and the data signal waveform is determined based on whether or not the amplitude value calculated by the amplitude calculating means is within a predetermined range. It is determined whether or not the laser power of the recording is appropriate, and if it is determined that the laser power at the time of recording is not appropriate, a recording operation error has occurred. And a control means for judging that the drive device is in the right position. 7. When the control unit determines that the laser power at the time of recording is not appropriate and determines that a recording operation error has occurred,
7. The drive device according to claim 6, wherein a retry of a recording operation and a reading operation is performed by changing a recording laser power. 8. When the control means supplies recording data to the head means to execute writing of data on a recording medium, and then executes reading of a data signal for the recorded data. 7. The drive device according to claim 6, wherein when a decoding error occurs in the decoding unit, a retry of a recording operation and a reading operation is performed without changing a recording laser power. 9. The method according to claim 1, wherein the control unit calculates the amplitude by using the amplitude calculating unit if the decoding error remains even after the retry of the recording operation and the reading operation is performed a predetermined number of times without changing the recording laser power. It is determined whether or not the laser power at the time of recording is appropriate based on whether or not the amplitude value is within a predetermined range, and if it is determined that the laser power at the time of recording is not appropriate, the recording laser power is changed. 9. The drive device according to claim 8, wherein a retry of the recording operation is performed by performing the operation. 10. When the control means supplies recording data to the head means to execute writing of data to a recording medium, and then executes reading of a data signal for the recorded data. If the decoding is OK in the decoding means, it is determined whether the laser power at the time of recording is appropriate based on whether the amplitude value calculated by the amplitude calculation means is within a predetermined range, 7. The drive device according to claim 6, wherein when it is determined that the laser power at the time of recording is not appropriate, the recording laser power is changed and a retry of the recording operation is executed.