JPH11296856A - Method and device for optical disk reproducing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for reproducing optical disk, which is capable of suppressing fluctuation in DO detecting sensitivity caused by the change of data transfer speed. SOLUTION: This device is provided with a pickup 12, an RF amplifier 13, a data slicing part 14, a PLL part 19, a servo control unit 16, a data demodulating part 21, a mechanical driver part 17, a DO detecting part 15 having detecting sensitivity decided by a control voltage corresponding to a data transfer speed and outputting a detecting output assumingly indicating as the existence of dusts or the like on the surface of an optical disk 11 to the servo control unit 16 when the RF signal of the RF amplifier 13 is smaller than a threshold value, and an F/V converter 20 for converting the synchronous clock frequency of the PLL part 19 into a voltage and generating a control voltage corresponding to the data transfer speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk reproducing method and an optical disk apparatus for detecting a loss of an RF signal caused by dust or scratches on the surface of a disk in a disk.

[0002]

2. Description of the Related Art FIG. 8 shows an example of the configuration of an optical disk reproducing apparatus including a conventional DO (dropout) detecting apparatus for detecting a loss of an RF signal due to dust or the like on a disk surface. In FIG. 8, a reproduction RF signal including media information detected using light as a medium from an optical disk 51 is supplied to an RF amplifier 53 via a pickup 52, and an analog reproduction signal of the RF amplifier 53 is supplied to a data slice unit 54.
Is supplied to the DO detection unit 55, and the data binarized by the data slice unit 54 is supplied to the PLL unit 59. The clock signal and the data signal generated by the PLL unit 59 are used for controlling the rotation of the spindle 58. A servo control unit 56;
The data is supplied to the data demodulation unit 60, and the RF amplifier 53
An error signal for servo control for controlling the position of the pickup is supplied to the servo control unit 56, and the servo control unit 5
Reference numeral 6 is connected to the mechanical driver 57, and drives the actuator of the pickup 52 and the spindle motor 58 from the mechanical driver 57.

FIG. 9 illustrates the occurrence of RF signal dropout. FIG. 9A shows the appearance of dust 7 on the disk surface.
The state where 0 is attached is seen on a partial plane. Reference numeral 71 denotes a pit. FIG. 3B is a cross-sectional view of the disk. FIG. 3C shows a pickup 5 corresponding to the optical disk 51.
2 shows the reproduced RF signal output from the signal generator 2, and indicates that the signal output is reduced in response to the dust 70.

In such a configuration, the DO detection unit 55
Is the optical disk 51 like the RF waveform shown in FIG.
The envelope of the reproduced RF signal fluctuates abruptly due to dust 70, scratches, etc. existing on the upper portion, or the signal is lost, the error rate of the data converted from an analog signal to a digital signal in the data slice section 54 is deteriorated, and the servo is disturbed. This prevents the preavailability of the media from deteriorating due to occurrence of the above. For this purpose, the DO detection unit 55 detects the RF signal using a DO detection method as shown in FIG.

FIG. 10 (a) shows a DO detection circuit using a detection circuit, and FIG. 10 (b) shows a waveform of the DO detection circuit at the positions of. In FIG. 10A, reference numeral 75 denotes a low-speed peak detection circuit, 76 denotes a level shift circuit, 77 denotes a high-speed peak detection circuit, 78 denotes comparators, and I ₁ and I _2.
Is a current source, C ₁ and C ₂ (C ₂ << C ₁ ) are capacitors (capacitances), and Tr ₁ and Tr ₂ are transistors.

A signal obtained by level-shifting an envelope signal of an RF signal obtained through a low-speed peak detection circuit 75 by a level shift circuit 76 (FIG. 10B).
And the signal obtained by the high-speed peak detection circuit 77 (FIG. 10).
(B)) is compared by a comparator (comparator) 78 at the next stage, and when the high-speed envelope value becomes smaller than the reference low-speed envelope value, it is determined as DO (dropout) and the detection signal is determined. Is output to the servo control unit 56 (of FIG. 10B). To determine the DO sensitivity at this time, the level shift amount of the slow peak detection voltage which determines the Vth of the comparator 78 (threshold), a capacitor C ₂ in the high-speed peak detector circuit 77, a current source for discharging is determined by I _2, in particular wound, the slope of the amplitude variations of the RF signal by the waste 70 because vary depending on the data transfer rate, in accordance with the predetermined data rate, the capacitor C ₂
When, by determining the discharging current source I _2, DO detection sensitivity is determined only by the level shift amount of voltage obtained at low speed peak detection.

FIG. 11 shows amplitude fluctuation dV / dt and dV / d
FIG. 11 shows an example in which t = −I ₂ / C ₂ is set, and by setting a DO detector 55 as shown in FIG. 11, servo disturbance or the like at the time of DO is corrected, and the pre-ability of the medium is improved. be able to.

[0008]

In the conventional configuration, for example, a compact disk for music (hereinafter abbreviated as CD)
As in the case of the reproduction of FIG.
In the case of the LV control (a control method for keeping the linear velocity constant),
Since the data transfer speed is a specific value, the gradient of the amplitude fluctuation of the RF signal is uniquely determined, and the detection sensitivity of the DO detector can be fixed. In the case of an optical disc reproducing apparatus in which the rotation control is CAV control (a control method for keeping the angular velocity constant), as shown in FIG. 2, the data transfer rate handled is plural or variable. If the detection sensitivity of the detector 55 is set, the envelope waveform of the high-speed peak detector 77 cannot follow the gradient of the RF amplitude fluctuation.

FIG. 12A shows an RF signal at a normal speed, an envelope waveform and a threshold value Vth (a) of the high speed peak detection circuit 77, and a DO detection output (b).
FIG. 2B shows the RF signal and the like (a) and the DO detection output (b) at twice the normal speed, and in FIG. 2B, the slope of the RF amplitude fluctuation becomes steep. As a result, the envelope waveform cannot follow the slope, so that the error time d
and the detection output width is shortened. As a result, as shown in FIG.
There is a problem that the O detection sensitivity accuracy is deteriorated and the pre-ability of the disc is reduced.

Accordingly, an object of the present invention is to provide an optical disk reproducing apparatus capable of suppressing a change in DO detection sensitivity due to a change in data transfer speed.

[0011]

According to a first aspect of the present invention, there is provided a method of reproducing an optical disk, wherein a dropout detection sensitivity of a reproduction signal taken out of the optical disk is adjusted in accordance with a rotation speed of a dropout position of the optical disk. Is what you do. According to the optical disk reproducing method of the first aspect, by adjusting the DO detection sensitivity in accordance with the data transfer speed, it is possible to suppress a change in the DO detection sensitivity due to a change in the data transfer speed.

According to a second aspect of the present invention, there is provided an optical disk reproducing apparatus for picking up information recorded on an optical disk, an RF amplifier for generating an RF signal and a servo control error signal from a reproduced RF signal generated from the optical pickup, A data slice unit for binarizing the RF signal, a PLL unit for generating data and a synchronous clock from the RF signal binarized by the data slice unit, and a PLL for receiving an error signal for servo control of the RF amplifier
A servo control unit for inputting data and a synchronous clock of the unit and outputting a drive signal, a data demodulation unit for demodulating data, and a drive signal of the servo control unit for inputting a drive signal to control the position of the pickup and control the spindle motor. When the RF signal of the RF amplifier is smaller than the threshold value with the detection sensitivity determined by the mechanical driver unit and the control voltage corresponding to the data transfer speed, the servo controller determines that there is dust on the surface of the optical disk and outputs a detection output to the servo control unit. It is provided with a DO detection unit to be supplied, and a speed / voltage converter that generates a control voltage corresponding to the data transfer speed.

According to the optical disk reproducing apparatus of the present invention, a speed / voltage converter, for example, generates a frequency synchronized with a data transfer speed from a synchronous clock obtained through a PLL unit from an RF signal taken out of the optical disk, An F / V converter that converts the frequency of the synchronous clock to a voltage proportional to the frequency generates a voltage corresponding to the data transfer rate, and uses the voltage as a control voltage for adjusting the detection sensitivity of the DO detection unit. In addition, the DO detection sensitivity can be automatically adjusted according to the data transfer speed of the reproduction signal, and the DO detection accuracy of the RF signal can be improved.

As described above, by providing the DO detector having the function of automatically adjusting the detection sensitivity to the optimum detection sensitivity according to the transfer speed, fluctuations in the DO detection sensitivity due to a change in the data transfer speed are suppressed, and excellent preavailability is provided. An optical disc reproducing apparatus having the above structure can be realized. According to a third aspect of the present invention, there is provided an optical disc reproducing apparatus for picking up information recorded on an optical disc, an RF amplifier for generating an RF signal and a servo control error signal from a reproduced RF signal generated from the pickup, and A data slice to be binarized, and an RF binarized by the data slice
A PLL unit for generating data and a synchronous clock from a signal, a servo control unit for receiving an error signal for servo control of the RF amplifier, and for inputting the data and the synchronous clock of the PLL unit and outputting a drive signal, and the servo control unit A mechanical driver unit that inputs a drive signal of the pickup to control the position of the pickup and control the spindle motor;
A DO detection unit that has a detection sensitivity determined by a control voltage corresponding to the data transfer speed and supplies a detection output to a servo control unit assuming that dust or the like is present on the surface of the optical disk when the RF signal of the RF amplifier is smaller than a threshold value. A data demodulation unit for extracting address information from data in the PLL unit, and a D / A converter for converting the address value obtained from the data demodulation unit into a voltage to generate a control voltage corresponding to the data transfer rate. It is provided.

According to the third aspect of the present invention, the address information is extracted from the data generated by the data demodulator, and the obtained address value is converted into a voltage by the D / A converter. By using the control voltage for adjusting the detection sensitivity, the DO detection sensitivity can be automatically adjusted in accordance with the data transfer speed of the reproduction signal, and the DO detection accuracy of the RF signal can be improved. .

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a first embodiment of an optical disk reproducing apparatus including a DO detection unit according to the present invention. In FIG. 1, 11 is an optical disk, 12 is a pickup, 13 is an RF amplifier, 14 is a data slice unit,
5 is a DO detection unit, 16 is a servo control unit, 17 is a mechanical driver unit, 18 is a spindle motor, and 19 is a PLL (Phas
e Locked Loop) section 20 converts the synchronous clock of the PLL section 19 into a voltage proportional to the frequency, and outputs the voltage to the DO detection section 15.
An F / V converter as an example of a speed-voltage converter, which generates a control voltage that adjusts the detection sensitivity, that is, the detection sensitivity of the F / V converter;
21 is a data demodulation unit. These connections are as shown in the figure.

First, in this optical disk reproducing method, the dropout detection sensitivity of a reproduction signal taken out of the optical disk 11 is adjusted according to the rotation speed of the optical disk 11 at the dropout position. Referring to FIG. 1, a reproduced RF signal detected from the optical disk 11 using light as a medium is transmitted to the RF amplifier 13 via the pickup 12.
, And the RF amplifier 13
And the DO detection unit 15 and an analog reproduction signal, and the data binarized by the data slice unit 14 is supplied to a PLL unit 19. The clock signal and the data signal generated by the PLL unit 19 control the rotation of the spindle. For this purpose, it is supplied to the servo controller 16 and to the data demodulator 21. Also, the synchronous clock generated by the PLL unit 19 is
It is connected to the V converter 20 and supplies a voltage proportional to the clock frequency to the DO detector 15. The RF amplifier 13
An error signal for servo control for controlling the position of the pickup 12 is supplied to the servo control unit 16. The servo control unit 16 is connected to a mechanical driver unit 17, and the actuator of the pickup 12 and the spindle motor 18 are transmitted from the mechanical driver unit 17. Is driven.

When the DO detecting section 15 is configured as shown in FIG. 1, the reproduced RF signal is converted into digital data via the pickup 12, the RF amplifier 13, and the data slicing section 14. A synchronized clock is generated. This synchronous clock signal changes as shown in FIG. 2 depending on the rotation control method of the optical disk 11. That is, FIG. 2A shows the characteristics of CAV control,
Although the rotation speed of the optical disk 11 is constant, the data transfer speed and the linear speed increase proportionally on the outermost periphery of the optical disk 11. FIG. 2B shows the CLV control, in which the data transfer speed and the linear speed are constant, but the number of rotations decreases in proportion to the outermost circumference of the optical disk 11.

Once the data transfer rate is determined, the frequency of the synchronous clock signal is uniquely determined. Therefore, the PLL unit 1
9 is an F / V signal shown in FIG.
It is connected to an F / V converter 20 having a conversion characteristic to generate a voltage proportional to the frequency of the synchronous clock signal,
The control voltage of the O detection sensitivity is used, for example, as a control voltage of a current source that determines the detection sensitivity. That is, the output of the F / V converter 20 is input to the input unit of the DO detection unit 15, whereby the DO detection sensitivity can be automatically adjusted according to the data transfer speed as shown in FIG.

FIGS. 4A and 4B show the detection operation. FIG. 4A shows the DO detection timing at a normal data transfer speed, FIG. 4A shows the RF signal, envelope and threshold, and FIG.
O detection output. FIG. 2B shows the DO detection timing when the data transfer rate is twice the normal data transfer rate, FIG. 2A shows the RF signal, envelope and threshold, and FIG.
This is a detection output. As is clear from the comparison with FIG. 11 (2), the follow-up of the envelope with respect to the speed fluctuation can be ensured, so that the error time dt can be eliminated.

A second embodiment of the present invention will be described with reference to FIGS. FIG. 5 shows a second embodiment of the optical disk reproducing apparatus including the DO detection section of the present invention. In FIG. 5, 31 is an optical disk, 32 is a pickup,
33 is an RF amplifier, 34 is a data slice unit, 35 is D
O detection unit, 36 is a servo control unit, 37 is a mechanical driver unit, 38 is a spindle motor, 39 is a PLL (Phase Lo
cked Loop) unit, 40 is a D / A converter, and 41 is a data demodulation unit. These connections are as shown in the figure.

A reproduction RF signal detected from the optical disk 31 using light as a medium is supplied to an RF amplifier 33 via a pickup 32, and the RF amplifier 33 supplies an analog reproduction signal to a data slice unit 34 and a DO detection unit 35. The data binarized by the data slice unit 34 is
The clock signal and the data signal supplied to the L unit 39 and generated by the PLL unit 39 are supplied to the servo control unit 36 and the data demodulation unit 41 for controlling the rotation of the spindle.
A voltage value corresponding to the address value extracted from the data demodulation unit 41 is generated from the D / A converter 40, and
A voltage corresponding to the address value on 1 is supplied to the input unit of the DO detection unit 35. Further, the RF amplifier 33 is supplied with a servo control error signal for controlling the position of the pickup 32 to the servo control unit 36, and the servo control unit 36 is connected to the mechanical driver unit 37 and the pickup 32 Actuator and spindle motor 3
8 is driven.

When the DO detection unit 35 is configured as shown in FIG. 5, when the rotation control of the spindle motor 38 is performed by the CAV control, the angular velocity and the number of rotations are constant at any place of the optical disk 31 as shown in FIG. However, since the linear velocity and the data transfer rate become faster toward the outer circumference, the data transfer rate is uniquely determined if the position where the pickup 32 takes in, in other words, the address value of the optical disk 31 is determined. Therefore, the address value demodulated by the data demodulator 41 is generated by the D / A converter 40 having a conversion characteristic as shown in FIG.
The detection sensitivity is supplied to the DO detector 35 and used for the control voltage of the current source for determining the detection sensitivity in the same manner as in the first embodiment, and the detection sensitivity changes in proportion to the address value on the optical disk 31 and the data transfer speed. By providing the DO detector 35, the DO detection sensitivity can be automatically adjusted according to the data transfer speed.

In the above invention, the case where the data transfer rate changes linearly is assumed, but the present invention is also applicable to the case where the data transfer rate changes stepwise. Further, the present invention can be applied to the case where both of the inventions of claim 1 (first embodiment) and claim 2 (second embodiment) are used in combination and switched between them. FIG. 7 shows a modification of the first embodiment, in which the frequency of the FG signal output from the spindle motor 18 is converted into a voltage proportional to the rotation speed by an F / V conversion circuit 20 '.
The detection sensitivity of the detection unit 15 is automatically adjusted.

[0025]

According to the optical disk reproducing method of the first aspect, by adjusting the DO detection sensitivity in accordance with the data transfer speed, it is possible to suppress a change in the DO detection sensitivity due to a change in the data transfer speed. According to the optical disk reproducing apparatus of the second aspect, a speed / voltage converter, for example, generates a frequency synchronized with the data transfer speed from a synchronous clock obtained through a PLL unit for an RF signal taken out of the optical disk, and generates a frequency of the synchronous clock. An F / V converter that converts the frequency to a voltage proportional to the frequency generates a voltage corresponding to the data transfer rate, and uses the voltage as a control voltage for adjusting the detection sensitivity of the DO detection unit. The DO detection sensitivity can be automatically adjusted in accordance with the data transfer speed, and the DO detection accuracy of the RF signal can be increased.

As described above, by providing the DO detector having the function of automatically adjusting the detection sensitivity to the optimum detection sensitivity according to the transfer speed, fluctuations in the DO detection sensitivity due to a change in the data transfer speed are suppressed, and excellent preavailability is achieved. An optical disc reproducing apparatus having the above structure can be realized. According to the optical disk reproducing apparatus of the third aspect, the address information is extracted from the data generated from the data demodulator, and the obtained address value is converted to the D / D.
By converting the voltage with the A converter and using the control voltage for adjusting the detection sensitivity of the DO detection unit, the DO detection sensitivity can be automatically adjusted in accordance with the data transfer speed of the reproduction signal as in the first embodiment. , The DO detection accuracy of the RF signal can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical disc reproducing device according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram of rotation control of a spindle motor.

FIG. 3 is a characteristic diagram of the F / V converter according to the first embodiment.

FIG. 4 is an explanatory diagram of an operation of the DO detector according to the first embodiment.

FIG. 5 is a block diagram of an optical disc reproducing device according to a second embodiment of the present invention.

FIG. 6 is a characteristic diagram of a D / A converter according to the second embodiment.

FIG. 7 is a block diagram of a modification of the first embodiment.

FIG. 8 is a block diagram of a conventional optical disc reproducing apparatus.

FIG. 9 is an explanatory diagram of occurrence of a dropout (DO).

FIG. 10 is a circuit block diagram of a DO detector.

FIG. 11 is a diagram illustrating the operation of a DO detector of a conventional optical disc reproducing apparatus.

FIG. 12 is an explanatory diagram of a problem of a DO detector of a conventional optical disc reproducing apparatus.

[Explanation of symbols]

 11, 31, 51 Optical disk 12, 32, 52 Pickup 13, 33, 53 RF amplifier 14, 34, 54 Data slice unit 15, 35, 55 DO detector 16, 36, 56 Servo control unit 17, 37, 57 Mechanical drive Unit 18, 38, 58 Spindle motor 19, 39, 59 PLL unit 20 F / V converter 40 D / A converter 21, 41, 60 Data demodulator

Claims (3)

[Claims] 1. An optical disk reproducing method comprising: adjusting a dropout detection sensitivity of a reproduction signal taken out of an optical disk in accordance with a rotation speed of a dropout position of the optical disk. 2. A pickup for extracting information recorded on an optical disk, an RF amplifier for generating an RF signal and a servo control error signal from a reproduced RF signal generated from the pickup, and binarizing the RF signal. A data slice section, a PLL section for generating data and a synchronization clock from the RF signal binarized by the data slice section, and a servo control error signal for the RF amplifier, and a data section for the PLL section; And a servo control unit that inputs a synchronization clock and outputs a drive signal, and a data demodulation unit that demodulates the data,
A mechanical driver for inputting the drive signal of the servo controller and controlling the position of the pickup and controlling the spindle motor; and a detection driver for the RF amplifier having a detection sensitivity determined by a control voltage corresponding to a data transfer speed. When the RF signal is smaller than a threshold value, a DO detection unit that supplies a detection output to the servo control unit assuming that dust or the like is present on the surface of the optical disc, and generates the control voltage corresponding to the data transfer speed. An optical disk reproducing device including a speed / voltage conversion device. 3. A pickup for extracting information recorded on an optical disc, an RF amplifier for generating an RF signal and a servo control error signal from a reproduced RF signal generated from the pickup, and binarizing the RF signal. A data slice section, a PLL section for generating data and a synchronization clock from the RF signal binarized by the data slice section, and a servo control error signal for the RF amplifier, and a data section for the PLL section; A servo control unit for inputting a drive signal by inputting a synchronous clock and a mechanical driver unit for inputting the drive signal of the servo control unit to control the position of the pickup and control the spindle motor; Having a detection sensitivity determined by a control voltage corresponding to A DO detection unit that supplies a detection output to the servo control unit when the RF signal is smaller than a threshold value and that the surface of the optical disc has dust or the like;
A data demodulation unit for extracting address information from the data of the L unit, and a D / A converter for converting the address value obtained from the data demodulation unit into a voltage to generate the control voltage corresponding to the data transfer speed; An optical disc reproducing device provided with the.