WO2002031820A1

WO2002031820A1 - Disk unit

Info

Publication number: WO2002031820A1
Application number: PCT/JP2001/008736
Authority: WO
Inventors: Koichi Tada; Tadashi Okajima; Toshihide Hamaguchi; Toshio Takahashi
Original assignee: Sanyo Electric Co., Ltd.
Priority date: 2000-10-10
Filing date: 2001-10-03
Publication date: 2002-04-18
Also published as: JP2002117537A

Abstract

A disk unit (10) including a peak hold circuit (32) for detecting the peak level of an FCM signal and a bottom hold circuit (34) for detecting the bottom level of an FCM signal. A DPS (42) determines a peak slice level based on a peak level detected by the peak hold circuit (32), and determines a bottom slice level based on a bottom level detected by the bottom hold circuit (34). The level of an FCM signal is compared to a peak slice level by a comparator (36a), and to a bottom slice level by a comparator (36b). A judging circuit (38) judges an FMC signal based on comparison signals output from the comparators (36a) and (36b).

Description

Specification

Disk unit technical field

The present invention relates to a disk drive, and more particularly to, for example, irradiating a laser beam to a disk recording medium having predetermined marks formed on a track at predetermined intervals, so that the amplitude related to the predetermined marks and the amplitude in the positive and negative directions are increased. The present invention relates to a disk device that detects a predetermined mark signal that changes to a state. Conventional technology

In a magneto-optical disk such as an ASM (Advanced Storage Magneto Optical disc), FCMs (Fine Clock Marks) are formed at predetermined intervals on land tracks and groove tracks. Therefore, if a land track or a group track is traced, an FCM signal is detected based on the laser light reflected from the disk. The FCM signal is a positive / negative symmetric signal whose level changes to the positive side and the negative side. Therefore, whether the detection signal is an FCM signal or whether the detection signal is a signal that changes first from the positive side or a signal that changes first from the negative side depends on the level of the detection signal. And the slice level of the negative polarity.

However, the level of the FCM signal does not always change symmetrically. In other words, the level of the FCM signal may be asymmetrical depending on the offset based on the radial tilt of the disc. If the positive and negative slice levels are always fixed, the FCM signal may not be accurately determined. Summary of the Invention

Therefore, a main object of the present invention is to provide a novel disk drive.

Another object of the present invention is to provide a disk drive capable of appropriately discriminating a signal even when a signal that should change vertically symmetrically changes vertically asymmetrically. You.

Tracks are formed on the recording surface of the disk recording medium, and predetermined marks are formed along the tracks. When the rotating means rotates the disk recording medium, the predetermined mark signal detecting means detects the predetermined mark signal by irradiating a laser beam along the track. The predetermined mark signal is related to the predetermined mark, and the level of this signal changes to the positive side and the negative side from the reference level.

The first determining means determines the first slice level on the positive electrode side based on the peak level of the predetermined mark signal, and the second determining means determines the second slice level on the negative electrode side based on the bottom level of the predetermined mark signal. . The level of the predetermined mark signal is compared with the first slice level by the first comparing means, and is compared with the second slice level by the second comparing means. The determining means determines the predetermined mark signal based on a comparison result by the first comparing means and the second comparing means.

As described above, since the first slice level and the second slice level are respectively determined from the peak level and the potom level of the predetermined mark signal, even if the predetermined mark signal includes an offset, the first slice level is the peak level. The second slice level does not fall below the bottom level. For this reason, the predetermined signal can be appropriately determined from the comparison result of the first comparing means and the second comparing means.

Preferably, a convex first track and a concave second track are formed on a recording surface of a disk recording medium. The predetermined mark on the first track is formed in a concave shape, and the predetermined mark on the second track is formed in a convex shape. The determining means determines whether the predetermined mark signal starts to change from the positive electrode side or the negative electrode side based on the comparison result.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram showing one embodiment of the present invention;

Figure 2 is a perspective view of the recording surface of the disc; FIG. 3 (A) is a waveform diagram showing a tracking error signal;

FIG. 3 (B) is a waveform diagram showing the TZC signal;

FIG. 4A is a waveform diagram showing an FCM signal detected from a land track; FIG. 4B is a waveform diagram showing an FCM signal detected from a groove track; FIG. A waveform diagram showing an example of a comparison signal;

FIG. 4 (D) is a waveform diagram showing another example of the comparison signal;

FIG. 5 is an illustrative view showing a relationship between a tracking error signal and a tracking actuator control signal;

Figure 6 is a circuit diagram showing the configuration of the photodetector, TE signal detection circuit, FE signal detection circuit and FCM signal detection circuit;

FIG. 7 is a flowchart showing a part of the operation of the embodiment of FIG. 1; and

FIG. 8 is a waveform diagram showing an example of the FCM signal. BEST MODE FOR CARRYING OUT THE INVENTION

Referring to FIG. 1, an optical disk device 10 of this embodiment includes an optical pickup 12 provided with an optical lens 14. The optical lens 14 is supported by the tracking activator 16 and the focus actor 18. The laser light emitted from the laser diode 20 is converged by the optical lens 14 and applied to the recording surface of a magneto-optical disk 50 such as an ASMO (Advanced Storage Magneto Optical disc). Thereby, a desired signal is recorded on the magneto-optical disk 50, or a desired signal is reproduced from the magneto-optical disk 50.

The magneto-optical disk 50 is mounted on a spindle 52 and is rotated by a spindle motor 54. The magneto-optical disk 50 is a ZCLV (Zone Constant Linear Velocity) type disk, and the number of rotations decreases as the optical pickup 12 moves from the inner circumference to the outer circumference.

In the radial direction of the surface of the magneto-optical disk 50, land tracks and groove tracks are alternately formed for each track, as shown in FIG. Each track is embossed with FCM at predetermined intervals. Specifically, the land track is formed in a convex shape, and the FCM on the land track is formed in a concave shape. Groove track is concave The FCM on the groove track is formed in a convex shape.

The laser light reflected from such a disk surface passes through the optical lens 14 and irradiates the photodetector 22. The output of the photodetector 22 is input to an FE signal detection circuit 24 and a TE signal detection circuit 26. The FE signal detection circuit 24 detects a FE (Focus Error) signal based on the output of the photodetector 22, and the TE signal detection circuit 26 detects a TE (Tracking Error) signal based on the output of the photodetector 22. The detected FE signal and TE signal are supplied to a DSP (Digital Signal Processor) 4 via AZD converters 40a and 40b, respectively.

The DSP 42 executes focus servo processing based on the FE signal, and executes tracking servo processing and thread servo processing based on the TE signal. A focus actuating control signal is generated by the focus servo process, a tracking actuating control signal is generated by the tracking servo process, and a thread control signal is generated by the thread servo process. The focus actuating control signal is output to the focus actuating unit 18 via the DZA converter 44b, and the tracking actuating control signal is output via the DZA converter 44a. Is output to The thread control signal is converted into a PWM signal by a PWM signal generation circuit 46 and then output to a thread module 48.

The TE signal is also compared to a threshold in comparator 33. The comparator 33 outputs a TZC (Tracking Zero Cross) signal. When the optical pickup 12 moves in the radial direction of the magneto-optical disk 50 for the seek operation, the TE signal draws the waveform shown in FIG. 3A, and the TZC signal draws the waveform shown in FIG. 3B. . In other words, the TZC signal rises at a zero level while the TE signal is changing from a negative level to a positive level, and falls at a zero level while the TE signal is changing from a positive level to a negative level. The TZC signal output from the comparator 33 is directly supplied to the DSP 42.

The output of the photodetector 22 is also input to the FCM signal detection circuit 28. The FCM signal detection circuit 28 generates an FCM signal based on the laser light reflected by the FCM.

The FCM signal is generated when the laser beam traces the FCM formed on the land track. The waveform shown in Fig. 4 (A) is drawn, and when the laser beam traces the FCM formed on the groove track, the waveform shown in Fig. 4 (B) is drawn.

The generated FCM signal is supplied to a peak hold circuit 32 and a bottom hold circuit 34 via a VCA (Voltage Controlled Amplifier) 30. The peak hold circuit 32 detects the peak level of the FCM signal, and the bottom hold circuit 34 detects the bottom level of the FCM signal. As a result, a peak hold signal having the peak level shown in FIG. 4A or 4B is output from the peak hold circuit 32, and the bottom hold signal shown in FIG. 4A or 4B is obtained. A bottom hold signal having a level is output from the pottom hold circuit 34. The output peak hold signal and bottom hold signal are supplied to DSP 42 via AZD converters 40c and 40d, respectively.

The DSP 42 generates a gain control signal for controlling the gain of the VCA 30 based on one of the peak hold signal and the bottom hold signal. The generated gain control signal is provided to VCA 30 via the DZA converter 44e. VCA 30 amplifies the FCM signal with a gain according to the gain control signal.

The DSP 42 also generates a peak slice signal for slicing the FCM signal near the peak level based on the peak hold signal, and generates a peak slice signal for slicing the FCM signal near the bottom level based on the pottom hold signal. Generate. The peak slice signal is given to the comparator 36a via the DZA converter 44c, and the bottom slice signal is given to the comparator 36b via the DZA converter 44d. The peak slice signal and the bottom slice signal have the peak slice level and the bottom slice level shown in FIG. 4 (A) or FIG. 4 (B), respectively. The comparators 36a and 36b compare the level of the FCM signal output from the VC A30 with the peak slice level and the bottom slice level, respectively.

The comparator 36a inputs the peak hold signal from the minus terminal and inputs the FCM signal from the plus terminal. The comparator 36b inputs the FCM signal from the negative terminal and the bottom hold signal from the positive terminal. Therefore, when the FCM signal changes as shown in Fig. 4 (A), the comparison signal shown in Fig. 4 (C) The signal is output from comparator 36a, and the comparison signal shown in Fig. 4 (D) is output from comparator 36b. On the other hand, when the FCM signal changes as shown in FIG. 4 (B), the comparison signal shown in FIG. 4 (D) is output from the comparator 36a, and the comparison signal shown in FIG. Output from

The determination circuit 38 determines whether the detection signal is an FCM signal and whether the detection signal is a signal that changes first from the positive side based on the phase relationship between the comparison signals output from the comparators 42 a and 42 b. Determine whether the signal changes from the negative side first. If the rise time of the output of the comparator 36a is earlier than the output of the comparator 36b by a predetermined period, it is determined that the FCM signal that changes first from the positive side is detected (that is, the current track is a land track). I do. On the other hand, if the rising timing of the output of the comparator 36a is later than the output of the comparator 36b by a predetermined period, an FCM signal that changes first from the negative side is detected (that is, the current track is Groove track). The determination result thus obtained is output to DSP42.

The DSP 42 inverts the polarity of the tracking work control signal when the current track is a land track. Referring to Fig. 5, the polarity of the TE signal and the tracking work overnight control signal may be the same when adjusting the tracking on the group track, but when the tracking is adjusted on the land track, the TE signal and the tracking signal may be adjusted. It is necessary to reverse the polarity of the tracking work control signal. Therefore, the DSP 42 controls the polarity of the tracking work control signal in accordance with the result of the determination by the determination circuit 38. Note that, in FIG. 5, the amplitude of the tracking work control signal is shown parallel to the horizontal axis, the outer periphery has a positive polarity, and the inner periphery has a negative polarity.

The photodetector 22, the FE signal detection circuit 24, the TE signal detection circuit 26, and the FCM signal detection circuit 28 are configured as shown in FIG. The photodetector 22 has four detection elements 22a to 22d. The outputs of the detection elements 22 a to 22 d are subjected to different calculations in the FE signal detection circuit 24, the TE signal detection circuit 26, and the FCM signal detection circuit 28. Specifically, Equation 1 is calculated in the FE signal detection circuit 24, and Equation 2 is calculated in the TE signal detection circuit 26. 1 \ 1 signal detection circuit 28 Equation 3 is calculated in.

[Number 1]

FE = (A + C)-(B + D)

[Number 2]

TE = (A + D) one (B + C)

[Number 3]

FCM = (A + B)-(C + D)

Note that “A” to “D” in Equations 1 to 3 correspond to the outputs of the detection elements 22 a to 22 d, respectively. The detection elements 22a and 22d detect the left half light component of the laser light in the trace direction, and the detection elements 22b and 22c detect the right half light component of the laser light in the trace direction.

The DSP 42 controls the peak slice level and the bottom slice level according to the flowchart shown in FIG. Although the DSP 42 is actually formed by a logic circuit, the operation will be described with reference to a flowchart for convenience of explanation.

First, in step S1, a peak hold signal is fetched from the A / D converter 40c. As a result, the peak level of the FCM signal is detected. When the peak level is detected, Equation 4 is calculated in step S3 to determine the peak slice level.

[Number 4]

P SL = (Y-2.5) +2.5

P S L: Peak slice level

K: 0 <K <1

Υ: Peak level

Referring to FIG. 8, the FCM signal draws a sine curve based on 2.5 V. Therefore, "Y-2.5" indicates the amplitude on the positive side from the reference level. The peak slice level is obtained by multiplying this amplitude by "K" and adding 2.5 to the multiplied value. In step S5 shown in FIG. 7, the peak slice signal having the calculated peak slice level is output to the comparator 36a via the DZA converter 44c. In step S7, a bottom hold signal is fetched from the A / D converter 40d. As a result, the bottom level of the FCM signal is detected. Bottom level detected Then, in step S9, the bottom slice level is obtained according to Equation 5.

[Number 5]

BSL = 2.5-K (2.5-Y-1)

BSL: Peak slice level

Y ': bottom level

Referring to FIG. 8, "2.5-Y '" indicates the amplitude on the negative side from the reference level. Multiply this amplitude by "K" and subtract this product from 2.5 to get the bottom slice level. In step S11 shown in FIG. 7, the bottom slice signal having the calculated bottom slice level is output to the comparator 36b via the D / A converter 44d.

As can be seen from the above description, a convex land track and a concave group track are formed on the recording surface of the magneto-optical disk 50. Also, a concave FCM is formed on the land track, and a concave FCM is formed on the groove track. When the magneto-optical disk 50 is rotated by the spindle motor 54, the optical pickup 12 irradiates a laser beam along a land track or a group track. The FCM signal detection circuit 28 detects the FCM signal based on the laser light reflected from the land track or groove track.

The peak hold circuit 32 detects the peak level of the FCM signal, and the DSP 42 determines the peak slice level based on the detected peak level. The bottom hold circuit 34 detects the bottom level of the FCM signal, and the DSP 42 determines the bottom slice level based on the detected bottom level. After the peak slice level and the bottom slice level are determined, the level of the FCM signal is compared with the peak slice level by the comparator 36a and by the comparator 36 with the bottom slice level. The determination circuit 38 determines the FCM signal based on the comparison signals output from the comparators 36a and 36b. In other words, based on the comparison signal, it is determined whether the FCM signal strength is detected and whether the detected FCM signal is a signal that changes first from the positive side or a signal that changes first from the negative side. Determine.

In this way, the peak slice and peak level of the FCM signal Is determined. Therefore, even if the FCM signal includes an offset, the peak slice level does not exceed the peak level, and the bottom slice level does not fall below the bottom level. Therefore, the FCM signal can be accurately determined.

While this invention has been described and illustrated in detail, it is obvious that it is used by way of illustration and example only and should not be construed as limiting, the spirit and scope of the invention being attached to Limited only by the language of the claim.

Claims

The scope of the claims

1. A disk drive with the following:

Rotating means for rotating a disk recording medium in which a track is formed on a recording surface and a predetermined mark is formed along the track;

A predetermined mark signal detecting means for irradiating the track with laser light to detect a predetermined mark signal related to the predetermined mark and whose level changes to a positive electrode side and a negative electrode side from a reference level;

First determining means for determining a first slice level on the positive electrode side based on a peak level of the predetermined mark signal;

First comparing means for comparing the level of the predetermined mark signal with the first slice level;

Second determining means for determining a second slice level on the negative electrode side based on a potential level of the predetermined mark signal;

Second comparing means for comparing the level of the predetermined mark signal with the second slice level; and

Determining means for determining the predetermined mark signal based on a comparison result of the first comparing means and the second comparing means;

2. A disk device according to claim 1, wherein a first convex track and a second concave track are formed on the recording surface, and the predetermined mark is formed concavely on the first track. It is formed in a convex shape on the second track.

3. A disk device according to claim 2, wherein the determination means determines whether the predetermined mark signal starts to change from the positive electrode side or the negative electrode side based on the comparison result.