JPH0581705A - Optical disk and optical disk device - Google Patents

Abstract

PURPOSE:To perform a stable focus setting by standardizing focus error signals. CONSTITUTION:When a magneto-optical disk 1 which has a mirror section in the inner most peripheral track is attached to a magneto-optical disk device, an optical pickup (OP) 3 moves to the inner most peripheral track of the magneto-optical disk and irradiates light to the mirror section. From the reflected light of the irradiated light, focus error signals are detected at a focus error converting circuit 8. In a peak detecting circuit 9, the difference between the maximum and the minimum values of the focus error signals (i.e., peak-to- peak values of an S shaped curve) is obtained. The resistance value of a variable resistor 11 is adjusted by a control circuit 10 in accordance with the computed peak-to-peak value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc for optically recording or reproducing information, an optical disc such as a magneto-optical disc, and an optical disc device for recording or reproducing information on the optical disc. The present invention relates to an optical disk device such as a magnetic disk device.

[0002]

2. Description of the Related Art For example, a magneto-optical disk in which servo control is performed by a sample servo system has a control signal recorded for each sector, and has a mirror portion that does not cause light diffraction in a part of the sector. The magneto-optical disk device irradiates the mirror portion with light, generates a focus error signal from the reflected light by a so-called astigmatism method, and performs focus servo control according to the focus error signal.

[0003]

By the way, when such a magneto-optical disk is mounted on a magneto-optical disk device to record or reproduce information, the mirror portion recorded on the magneto-optical disk immediately after mounting. Position cannot be determined (detected). Therefore, the magneto-optical disk device detects the focus error signal at an arbitrary position on the magneto-optical disk and performs lock-in control of the focus servo.

As described above, since the focus error signal is detected at an arbitrary position on the magneto-optical disk immediately after mounting the magneto-optical disk, in many cases, at a position where a pit formed on the magneto-optical disk exists. The focus error signal is detected. Therefore, the pit causes diffraction of the reflected light, and the focus error signal generated from the reflected light contains an error, which causes a problem that stable lock-in control of the focus servo cannot be performed.

Further, since the reflectivity of the magneto-optical disc and the reflectivity of the optical disc are greatly different, the dynamic range of the focus error signal generated from the reflected light becomes large, and stable focus servo control cannot be performed, so that the optical disc is There is a problem that it is difficult to realize an apparatus for recording or reproducing information which is also used as a magneto-optical disk.

The present invention has been made in view of such a situation, and is to normalize a focus error signal to enable stable lock-in control of a focus servo.

[0007]

An optical disc according to a first aspect of the invention is an optical disc in which information is optically recorded or reproduced, and at least a predetermined one track does not cause light diffraction. It is a mirror part.

The optical disk device according to a second aspect is
A focus error signal is generated from irradiation means such as an optical pickup 3 for irradiating an optical disk, which is a mirror portion in which at least one predetermined track does not cause light diffraction, and reflected light of the irradiated light. A focus error generating means including a focus error converting circuit 8 and the like, and a peak detecting circuit 9 for detecting a difference between the maximum value and the minimum value of the focus error signal in the mirror section.
And a standardizing means for standardizing the focus error signal according to the difference between the maximum value and the minimum value of the focus error signal in the mirror section.

[0009]

In the optical disc according to claim 1,
Since almost all of the predetermined at least one track is a mirror portion that does not cause light diffraction, stable focus servo lock-in control can be performed in advance on that track.

In the optical disc apparatus according to the second aspect, the maximum value of the focus error signal in the mirror portion of the optical disc, which is the mirror portion in which almost all of the predetermined at least one track does not cause light diffraction, The focus error signal is standardized by the difference from the minimum value. Therefore, stable lock-in control of the focus servo can be performed regardless of the type of the optical disc.

[0011]

1 is a block diagram showing the configuration of an embodiment of a magneto-optical disk device to which the optical disk device of the present invention is applied. The magneto-optical disk 1 is a magneto-optical disk to which the optical disk of the present invention is applied. For example, information is recorded or reproduced by a magneto-optical disk device in which servo control is performed by a sample servo system, and further, for example, an innermost track. Almost all of them are mirror parts.

A motor (M) 2 controls the rotation of the magneto-optical disk 1. The optical pickup (OP) 3 includes, for example, a semiconductor laser (not shown) and a light receiving element (not shown), collects light emitted from the semiconductor laser, and irradiates the target position on the magneto-optical disk 1. .. Further, OP3 receives the reflected light of the light applied to the magneto-optical disk 1, and the light receiving element converts this into an electric signal (voltage) proportional to the amount of received light.

Phase lock loop circuit (PLL) 4
Extracts a synchronization signal (clock signal) from the electric signal (RF signal) converted in OP3. In synchronization with the clock signal, the data separator 5 separates the recording signal from the RF signal output from OP3. The data decoder 6 decodes (reproduces) a data component from the signal output from the data separator 5. Address decoder 7
From the control signal output from the data separator 5,
The address indicating the position where the semiconductor laser of OP3 irradiates the magneto-optical disk 1 with light is decoded.

The focus error conversion circuit 8 generates a focus error signal from the reflected light of the magneto-optical disk 1. The peak detection circuit 9 detects the difference between the maximum value and the minimum value of the focus error signal output from the focus error detection circuit 8 in the mirror portion provided on the innermost track of the magneto-optical disk 1. This difference corresponds to a so-called S-shaped curve peak-to-peak value, which represents the relationship between the focus error signal and the distance between the magneto-optical disk 1 and the objective lens incorporated in OP3.

The control circuit 10 controls the resistance value of the variable resistor 11 in accordance with the peak-to-peak value output from the peak detection circuit 9. The variable resistor 11 is
The resistance value is controlled by the output of the peak detection circuit 10, and the focus error signal output from the focus error conversion circuit 8 is standardized (divided). Phase compensation circuit 1
Reference numeral 2 compensates the phase of the focus error signal divided by the variable resistor 11, and OP3, the focus error conversion circuit 8, the variable resistor 11, and the phase compensation circuit 12
And focus servo loop (system) consisting of amplifier 15
Is working stably. The amplifier 15 converts the standardized focus error signal output from the phase compensation circuit 12 into a voltage suitable for driving a focus actuator (not shown) configured to adjust the focus inside the OP3 ( Amplify).

The drive circuit 13 generates (outputs) a sawtooth wave.
Then, the focus actuator is driven. Switch 1
Reference numeral 4 switches between the sawtooth wave output from the drive circuit 13 and the focus error signal output via the phase compensation circuit 12, and supplies it to the focus actuator via the amplifier 15.

Next, the operation will be described. After the magneto-optical disk 1 having the innermost track as a mirror portion is mounted on the magneto-optical disk device, the motor 2 is controlled to rotate the mounted magneto-optical disk 1 at a predetermined rotation speed. It Next, OP3 stopped at an arbitrary position
Is a limit switch provided at a position where the light emitted from the semiconductor laser can be irradiated (focused) on the innermost track of the magneto-optical disk 1 by moving to the inner peripheral side of the magneto-optical disk 1. It stops by touching (not shown).

The stopped OP3 irradiates the mirror portion provided on the innermost track of the magneto-optical disk 1 with light and receives the reflected light. Further, the drive circuit 13 via the switch 14 and the amplifier 15 repeats the operation (focus search operation) of moving the objective lens built in OP3 from the far position to the near position with respect to the magneto-optical disk 1. , A drive signal of a sawtooth wave is supplied to the focus actuator. At this time, the focus error conversion circuit 8 generates a focus error signal from the received light by the astigmatism method. The focus error signal generated in this way is stored in the peak detection circuit 9, and until the peak detection circuit 9 detects the peak-to-peak value of the S-shaped curve (focus error signal),
P3 changes the focus position of the light emitted from the semiconductor laser.

When the peak detection circuit 9 detects the peak-to-peak value of the focus error signal, the value is input to the control circuit 10. The control circuit 10 controls the focus error signal from peak to peak.
Adjust the resistance value of the variable resistor 11 according to the peak value,
The focus error signal output from the focus error conversion circuit 8 is input to the phase compensation circuit 12 with a predetermined standard (constant dynamic range).

When the level of the focus error signal reaches a small value within a predetermined range, the switch 14 switches from the drive circuit 13 side to the phase compensation circuit 12 side. As a result, the standardized focus error signal (focus error signal of a predetermined dynamic range) is phase-compensated in the phase compensation circuit 12, amplified in the amplifier 15, and then output to the focus actuator. , Is driven according to the focus error signal.

After the focus pull-in (lock-in) is completed in this way, OP3 moves to the outer peripheral side of the magneto-optical disk 1. Then, in PLL4, OP3
When the clock is detected from the RF signal output from
In the data separator 5 in synchronization with the clock,
The signal is detected. Further, when the address decoder 7 detects wobbled pits for tracking from the signal output from the data separator 5, tracking is started and the address is read.

When the tracking is started in this way, the magneto-optical disk device is brought into a state in which information can be recorded on or reproduced from the magneto-optical disk 1.

As described above, in the present embodiment, the mirror portion is provided on almost all (the entire circumference) of the innermost track of the magneto-optical disk 1. However, for example, a limit switch for stopping OP3 is provided on the magneto-optical disk 1. A mirror portion may be provided at the position corresponding to the outermost track and the outermost track of the magneto-optical disk 1 may be provided.

Further, the optical disc device of the present invention is
Since the focus error signal is standardized and focus pull-in is performed, it is possible to record or reproduce information on the same device, for example, an optical disc or the like, which has greatly different reflectance, in addition to the above-described magneto-optical disc.

[0025]

According to the optical disk of the first aspect of the present invention, since substantially all of at least one predetermined track is a mirror portion, stable lock-in of focus servo control is performed in advance on that track. It can be carried out.

According to the optical disk device of the second aspect, the focus error signal is standardized by the difference between the maximum value and the minimum value of the focus error signal in the mirror portion in which at least one predetermined track does not cause light diffraction. It is supposed to change. Therefore, stable lock-in control of the focus servo can be performed regardless of the type of the optical disc.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a magneto-optical disk device to which an optical disk device of the present invention is applied.

[Explanation of symbols]

 1 Magneto-optical disk 2 Motor (M) 3 Optical pickup (OP) 4 Phase lock loop circuit (PLL) 5 Data separator 6 Data decoder 7 Address decoder 8 Focus error conversion circuit 9 Peak detection circuit 10 Control circuit 11 Variable resistor 12 Phase Compensation circuit 13 Drive circuit 14 Switch 15 Amplifier

Claims (2)

[Claims] 1. An optical disc for optically recording or reproducing information, wherein at least one predetermined track is a mirror portion that does not cause diffraction of light. 2. An irradiation unit for irradiating light onto an optical disc, which is a mirror unit in which all of at least one predetermined track does not diffract light, and a focus for generating a focus error signal from light passing through the optical disc. Error generating means, detecting means for detecting a difference between the maximum value and the minimum value of the focus error signal in the mirror section, and a difference between the maximum value and the minimum value of the focus error signal detected by the detecting means. An optical disc device, comprising: a normalization unit that normalizes the focus error signal.