JPH10149614A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk reproducing method with high reliability and safety and its device by preventing an actuator from heating up due to a face wobbling and eccentricity, etc., of a disk during the time of reproducing the disk. SOLUTION: Before reading out information recorded on the disk 1, eccentric and wobbling amts. of the disk are detected by eccentric amt. and wobbling amt. detecting means 11 and 21 respectively, and when the detected amts. are smaller than prescribed values without exceeding allowable power consumption, a reproducing speed of the disk 1 is set to a 1st reproducing speed to perform reproducing the disk 1. When the detected amts. are larger than the prescribed values, having possibility of exceeding the allowable power consumption, the reproducing speed of the disk 1 is set to a 2nd reproducing speed smaller than the 1st reproducing speed to contrive a decrease of the power consumption, so as to reproduce the disk 1 within allowable power consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for reproducing a disk using an optical pickup.
More particularly, the present invention relates to a reproducing method and apparatus suitable for preventing heat generation of an actuator of a pickup due to eccentricity or runout of a disk.

[0002]

2. Description of the Related Art In recent years, CD-ROMs in which a CD (compact disk) is applied to a read-only memory ROM (Read Only Memory) have been rapidly spreading. This CD-
ROM devices tend to increase in speed due to the demand for high-speed data transfer, and are expected to increase in speed from 6 × to 8 ×, and further to 12 × in recent years. Similarly, the speed of DVD-ROM devices is expected to increase in the future.

FIG. 11 is a schematic block diagram of a conventional servo mechanism for tracking control and focusing control of a pickup. The actuator 101 receives the electric signal V2
, And outputs a mechanical deviation X. The size, direction, and the like of X are detected by the detector 102 and become an electric signal V1. V1 is compared with the reference electric signal 103 (Vref) by the differential amplifier 104 to obtain a difference voltage Ve between them.
This is amplified by the amplifier 105 and fed back to the actuator 101.

FIG. 12 is a view showing the principle of the configuration of an actuator portion of an optical pickup for reproducing a disk.
Only one coil is shown for simplification of the description. That is, 1
It is a model of a three-dimensional actuator. Reference numeral 1 denotes an optical disk which rotates around an axis 201. The barrel 202 is the spring 20
3 and a coil 204 is attached. Since the magnetic field of the magnet 205 acts on the lens 204, the lens barrel 202 moves by receiving a current when a current flows through the coil 204. Only one coil is shown for simplification of the description. That is, it is a model of a one-dimensional actuator.

FIG. 13 is a general example of gain characteristics and phase transition characteristics of a tracking and focus actuator. When a force is applied to the mass (barrel 202) supported by the spring, the gain and phase of the transfer function between the force as input and the displacement as output exhibit characteristics such as 301 and 302 in FIG. 13, respectively. . The gain is flat up to f0 (a low-band resonance frequency determined by the movable mass, spring constant, frictional force, and the like of the actuator, which is a value of about 30 Hz for a general actuator). Attenuation is performed at 12 dB / oct to enter the attenuation region. On the other hand, the phase lag rapidly changes from zero to near π radians at f0. Note that fh in FIG. 7A is a high-band resonance frequency mainly generated by the vibration of the lens barrel 202, and the phase delay of 302 at fh is further increased.

[0006] Here, the recording / reproducing method of the CD-ROM is a CLV method with a constant linear velocity, like the conventional CD player, and the rotational speed changes according to the disk reproducing position.
The CLV is 1.2 m / sec as standard, and signal recording on the disk is defined in an area of 25 mm to 58 mm in the radial direction. (Speed) is about 8H
z, approximately 3 Hz at the position of the outermost periphery of 58 mm. Also, 4
Even when performing double-speed playback, the rotation frequency is approximately 32 Hz at the innermost circumference,
It is about 12 Hz even at the outermost periphery.

[0007]

However, in the case where the speed of the apparatus has been increased, for example, in the case of 8 × speed reproduction, the disk rotation frequency increases to about 64 Hz at the innermost position. That is,
It exceeds the low-band resonance frequency f0 of the actuator shown in FIG. This means an increase in power consumption of the actuator, that is, an increase in heat generation.
That is, due to the characteristics of the actuator, the actuator sensitivity drops secondarily in the region of f0 or more, so that the actuator applied voltage required to follow a certain amount of displacement must be increased. Therefore, the power consumption (heat generation) of the actuator is significantly increased as the speed of the device is increased. That is, the power consumption of the actuator is a function of the disk rotation frequency and the amount of displacement. The increase in power consumption due to the increase in the disk rotation frequency is due to the allowable power of the actuator coil itself and the increase in the temperature of the objective lens (of which plastic may be used) located in the vicinity due to heat generation. Is not practically acceptable.

In order to solve the above problem, the present invention provides a highly reliable and safe disk reproducing method and apparatus which prevent heat generation of an actuator due to disk runout and eccentricity during disk reproduction. It is in.

[0009]

The heat generated by the actuator is a problem when the actuator follows the eccentricity and runout of the disk and the power consumption at that time exceeds an allowable value. Therefore, when the eccentricity and the runout are small or the reproduction speed is low, there is no problem because the power consumption of the actuator for following does not exceed the allowable value.

Therefore, in order to achieve the above object, before reading the information recorded on the disk, the amount of eccentricity and runout of the disk is detected, and the detected amount is smaller than a predetermined value and exceeds the allowable power consumption. When there is no disc playback, the disc playback speed is set to the first playback speed, and the disc is played back.When the detection amount is more than a predetermined value and may exceed the allowable power consumption, the disc playback speed is set to the first playback speed. In this case, the power consumption is reduced by setting the second reproduction speed lower than the reproduction speed of the disk, and the disk is reproduced within the allowable power consumption.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below.

FIG. 1 is a block diagram of an optical disk device showing a first embodiment of the present invention. In the figure, 1 is a disk, 2 is a disk motor, 3 is a disk motor drive circuit, 4 is a motor control circuit, 5 is a rotation speed signal output from the disk motor 2, 6 is rotation speed detection means, 7 is an optical pickup, 8 is a demodulation circuit for demodulating the output of the optical pickup, 9 is a focus error detecting means, 10 is a focus error signal detected by the focus error detecting means 9, 11 is a surface shake amount detecting means, and 12 is a surface shake amount detecting means 11. The detected S-shaped waveform count signal, 13 is a phase compensation circuit, 14 is a voltage generation circuit, 15 is a switching circuit for switching between the phase compensation circuit 13 of the focus servo system and the voltage generation circuit 14, and 16 is a switching control for controlling the switching circuit 15. Signal, 17 is a drive amplifier of the focus servo system, and 18 is the voltage of the voltage generation circuit 14. Voltage control signal, the tracking error detection means 19, 20 is the tracking error signal detected from the tracking error detection means 19, the eccentric amount detecting means 21, 2
2 is a tracking error count signal detected by the eccentricity detecting means 21, 23 is a phase compensation circuit of the tracking servo system, 24 is a switch for turning on / off the tracking servo control, 25 is a switching control signal for controlling the switch 24, and 26 is a switching control signal. A drive amplifier for a tracking servo system; 27, a rotation speed switching signal for switching the rotation speed by the motor control circuit 4; 28, a rotation speed information signal for detecting a time required to make one rotation of the disk;
9 is a signal control circuit.

First, a method for detecting the amount of surface runout, which is one of the constituent elements of the present invention, will be described with reference to the flowchart of FIG. First, (a) the switch 15 is switched to the voltage generating circuit 14 by the switching control signal 16 output from the signal control circuit 28. Next, (b) a signal is sent from the motor control circuit 4 to the disk motor drive circuit 3 to drive the disk motor 2 and rotate the disk 1. Then, (c) the rotation speed signal detecting means 4 obtains rotation speed information of the disk motor 2 based on the rotation speed signal 5 output from the disk motor 2, and outputs the rotation speed information signal 2
As 7, the rotation of the disk motor 2 is controlled to be constant by feeding back to the motor control circuit 4. Furthermore,
(D) In accordance with the voltage control signal 18 from the signal control circuit 29, a voltage that changes stepwise or linearly is applied from the voltage generation circuit 14 to the focus actuator of the optical pickup via the drive amplifier 17. (E) As the output voltage of the voltage generating circuit 14 is increased, the objective lens inside the optical pickup approaches the disk.
Then, when the focal point of the objective lens passes through the disk surface, an error signal (focus error S-shaped waveform signal) in the form of “S” is output as the focus error signal. Then, (f) the surface shake detecting means 11 counts the number of the focus error S-shaped waveform signals included in the focus error signal 10 and outputs the S-shaped waveform count signal 12 according to the count result. (G) The signal control circuit 29 obtains the surface runout amount δ based on the information obtained from the S-shaped waveform count signal 12. Then, (h) and (v) the rotation speed switching signal 26 is output only when the surface runout δ exceeds a reference value δ1 described later, and the motor control circuit 4 lowers the information reproduction speed.

Next, referring to FIG.
An example of a specific configuration and its operation will be described. FIG. 3 is a block diagram of the surface runout detecting means 11, FIG. 4 is an explanatory diagram of the relationship between the surface runout of the disk and the count value of the focus error S-shaped waveform signal, and FIG. 5 is a flowchart of the surface runout detection. In FIG. 3, reference numeral 30 denotes a time generation circuit for generating a time corresponding to one rotation of the disk based on information obtained from the rotation speed information signal 27, and 31 denotes a focus error S-shaped occurring within a time corresponding to one rotation of the disk. A counter 32 counts the number of waveform signals. Reference numeral 32 denotes a count discriminating circuit that outputs the S-shaped waveform count signal 12 according to the number of times the counter 31 counts. First, a pulse waveform is generated by the time generation circuit 30 at each time corresponding to one rotation of the disk based on the rotation speed information signal 27. Then, based on the pulse waveform,
The counter 31 counts the number of focus error S-shaped waveform signals generated within a time corresponding to one rotation of the disk. Next, a method of detecting the amount of runout will be described with reference to FIGS. In FIG. 4, reference numeral 81 denotes an objective lens inside the optical pickup, and reference numeral 82 denotes a displacement amount of the disc with respect to the disc reference plane when the disc is rotated once. When a voltage is applied to the focus actuator by the voltage generation circuit 14 and the objective lens is moved closer to the disk, if the focal point F of the objective lens is farther from the disk rotating by the displacement δ, the focus error S-shaped waveform No signal is detected. Then, when the focal point F of the objective lens reaches the displacement amount −δ of the disk, the focus error S-shaped waveform signal is detected for the first time. At this time, the count number of the counter 31 becomes 1 or more. (A) In the count determination circuit 32, when the count number of the counter 31 becomes 1 or more, S
It outputs a character waveform count signal 12. (B) In the signal control circuit 28, when the first S-shaped waveform count signal 12 is detected, the data corresponding to the voltage V1 applied to the focus actuator is stored in the internal memory. When the output voltage of the voltage generation circuit 14 is further increased and the focal point F of the objective lens exceeds the displacement amount δ of the disk, the focus error S-shaped waveform signal is not detected. Therefore, (c) the count number becomes 0, and the S-shaped waveform count signal 12 is not output from the count determination circuit 32. (D) In the signal control circuit 28, data corresponding to the applied voltage V2 when the S-shaped waveform count signal 12 cannot be detected is stored in the internal memory.

Since the DC sensitivity of the actuator indicates the amount of displacement of the pickup with respect to the applied voltage, the surface deflection δ of the disk can be obtained by the following formula.

ΔV = V2−V1 (Formula (1) Disk runout δ = (actuator DC sensitivity) × {V △ 2} Formula (2) Therefore, the applied voltage value stored in the memory is By calculating the difference ΔV, the amount of surface runout can be calculated from Expressions (1) and (2). In the present embodiment, the signal control circuit 29 calculates the surface runout amount by software processing. FIG.
Shows a flowchart for generating the rotation speed switching signal 28. First, (A) △ V is calculated from the applied voltage values of V1 and V2 stored in the memory by using Expression (1).
(B) Next, the surface runout δ of the disk is calculated from V1 using the equation (2). Then, (c) the surface runout amount δ of the disk
Is smaller than δ1, the process is terminated, and (d) δ1
In the above case, the rotation speed switching signal 28 is output and the processing is terminated. When the rotation speed switching signal 28 is output, the disc motor control circuit 3 controls to reduce the information reproduction speed.

Here, δ1 is the amount of runout at which the power input to the focus actuator becomes a predetermined value Pf when following the runout of the disk at the runout frequency f determined by the rotation speed of the disk motor. Therefore, for example, when the allowable power consumption of the focus actuator is defined as Pfm, Pfm = Pf at the surface deflection frequency f obtained from the rotation speed information signal 28.
The reference value δ1 can be obtained by calculating δ1.

Next, a method of detecting the amount of eccentricity, which is one of the constituent elements of the present invention, will be described with reference to the flowcharts of FIGS. FIG. 7 is a schematic diagram showing a relationship between a track sectional view of the disk and a tracking error signal, and FIG. 8 is a flowchart showing a procedure for detecting an eccentric amount. In FIG. 7, 90 is a cross section of the track of the disk,
Reference numeral 91 denotes a tracking error signal. (A) First, the switch 15 is switched to the phase compensation circuit 13 side by the switching control signal 16, and the focus servo system is looped on. (B) Next, the switch 24 is turned off by the switching control signal 25, and the tracking servo control is turned off. As shown in FIG. 7, every time the focusing point of the objective lens in the tracking direction crosses adjacent tracks on the disk, an error signal (track crossing signal) having a substantially sine wave shape is output as the tracking error signal.
(C) Therefore, with the tracking servo control turned off, the number of the track crossing signals included in the tracking error signal 20 is counted by the eccentricity detecting means 21, and the count result is output as the tracking error count signal 21. The signal control circuit 29 obtains the amount of eccentricity δ based on the information obtained from the tracking error count signal 21 by a method described later. When the eccentricity δ of the disk is smaller than the reference value δ2, the process is terminated as it is, and the reference value δ
In the case of two or more, the rotation number switching signal 28 is output and the processing is terminated. When the rotation speed switching signal 28 is output, the disc motor control circuit 3 controls to reduce the information reproduction speed.

The eccentricity detecting means 21 will now be described with reference to FIG.
Will be described. FIG. 9 shows a block diagram of the eccentricity detecting means 21. In FIG. 9, reference numeral 40 denotes a rotation speed information signal 28.
A time generation circuit 41 generates a time corresponding to one rotation of the disk based on the obtained information, and a counter 41 counts the number of track crossing signals for each time corresponding to one rotation of the disk. First, a pulse waveform is generated by the time generation circuit 40 at each time corresponding to one rotation of the disk based on the rotation speed information signal 27. Then, based on the pulse waveform, the counter 41 counts the number of track crossing signals every time corresponding to one rotation of the disk, and outputs it as a tracking error count signal 22.

FIG. 10 shows the change in the relative position between the light spot and the track when the disk is rotated from the state where the light spot is on the Nth track when the rotation angle θ = 0 in the eccentric disk. FIG. FIG.
From 0, the tracking error count signal becomes 2 if 2M tracks are crossed when the disk is rotated once.
M, and the amount of eccentricity δ is a value obtained by multiplying M by the track pitch Tp. Therefore, the amount of eccentricity δ = 2M × Tp {2} Equation (3). In the case of a CD-ROM, the track pitch is 1.
6 μm. In this embodiment, the signal control circuit 29 calculates the amount of eccentricity by software processing. Therefore, the signal control circuit 29 calculates the eccentricity δ of the disk by using the equation (3). If the eccentricity δ of the disk is smaller than δ2, which will be described later, the process is terminated. After outputting the switching signal 28, the process ends. Then, when the rotation speed switching signal 28 is output, the disk motor control circuit 3 performs control to reduce the information reproduction speed.

Here, δ2 is the amount of eccentricity at which the power input to the tracking actuator when following the eccentricity of the disk at the eccentric frequency determined by the disk motor rotation speed becomes a predetermined value Pt. Therefore, for example, the allowable power consumption of the focus actuator is Pt
When m is defined as δ, Ptm = Pf at the eccentric frequency f obtained from the rotation speed information signal 28.
By calculating 2, the reference value δ2 can be obtained. Since the focus actuator and the tracking actuator are often arranged close to each other in the actuator of the optical disk, the allowable value of the power consumption is sometimes defined as the sum Pa of the two actuators.
At that time, it is necessary to set δ1 and δ2 so that the above-mentioned Pf + Pt does not exceed the allowable power consumption Pa of both actuators. At this time, Pf + Pt is δ1 and δ2
Although the reference values δ1 and δ2 are no longer fixed values because of the function of f, it is possible to deal with the same method by extending f to have a two-dimensional reference value table of δ1 and δ2. it can.

Generally, the cause of the eccentricity of the disk is a deviation of the center between the disk and the turntable in the horizontal direction. Therefore, even if the signal reproduction position changes in the radial direction, the change does not change much. Since the cause of the vibration is the deviation of the axis of the turntable from the vertical axis, the signal reproduction position becomes larger as it goes to the outer periphery, and its amount is almost proportional to the distance from the center. Further, in the high-speed reproduction region, when the relationship between the input voltage of the actuator and the displacement amount is simply expressed as 12 dB / oct, the frequency f, the displacement x, and the power consumption P are P = k × f4. × x2 (k is a constant) holds. Therefore, in this case, when the innermost circumference of the disk is reproduced, the power consumption of the actuator is the maximum. Therefore, when the amount of surface runout and the amount of eccentricity are equal to or less than the reference value at the innermost circumference, the actuator power consumption does not exceed the allowable value at another reproduction position. Therefore, when simplifying the processing, the processing described in the present invention is performed only once at the innermost circumference, and when the amount of surface runout and the amount of eccentricity are equal to or less than the reference value, it is not necessary to perform the subsequent processing. Absent.

In this manner, by controlling the actuator of the optical pickup so as not to be driven unnecessarily,
Heat generation of the actuator can be prevented.

[0024]

As described above, according to the present invention, before reproducing a disk, the eccentricity and the amount of runout of the disk are detected, and the disk is reproduced at an appropriate reproducing speed in accordance with the detected eccentricity and surface runout. Can be controlled. As a result, high-speed reproduction such as 8 × speed can be performed on a normal disk having small eccentricity and runout, and reproduction can be performed at an appropriate reproduction speed when the disk has large eccentricity and runout. The actuator is not driven unnecessarily, so that it is possible to prevent the actuator from generating heat.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical disc device showing a first embodiment of the present invention;

FIG. 2 is a flowchart of a method of detecting a surface runout amount,

FIG. 3 is a block diagram of a surface runout amount detecting unit 11;

FIG. 4 is an explanatory diagram of a relationship between a disk runout and a count value of a focus error S-shaped waveform signal;

FIG. 5 is a flowchart of surface runout detection,

FIG. 6 is a flowchart for generating a rotation speed switching signal 28;

FIG. 7 is a schematic diagram showing a relationship between a track cross-sectional view of a disk and a tracking error signal.

FIG. 8 is a flowchart showing a procedure for detecting the amount of eccentricity,

FIG. 9 is a block diagram of an eccentric amount detection unit 21;

FIG. 10 is a schematic diagram showing a change in a relative position between a light spot and a track when the disk is rotated in an eccentric disk.

FIG. 11 is a schematic block diagram of a conventional pickup servo mechanism.

FIG. 12 is a diagram showing the basic configuration of an actuator portion of an optical pickup.

FIG. 13 is a general example of a gain characteristic and a phase transition characteristic of an actuator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Disc, 2 ... Disk motor, 4 ... Motor control circuit, 5 ... Rotation speed signal, 6 ... Rotation speed detection means, 7 ... Optical pickup, 10 ... Focus error signal, 11 ... Surface runout amount detection means, 12 ... S Character waveform count signal, 14 voltage generation circuit, 18 voltage control signal, 20 tracking error, 21 eccentricity detection means, 22 tracking error count signal, 27 rotation speed switching signal, 28 rotation speed information signal.

Claims (4)

[Claims] 1. A means for rotating a disk, a focus error detection means for detecting a focus error signal, a focus servo control means for performing focus control on the disk, and an on / off operation of the focus servo control means. Switch means for applying a voltage to the focus actuator section, means for detecting the amount of surface runout of the disk, and a second playback speed lower than the first playback speed or the first playback speed. An optical disk apparatus comprising: a switching control means for switching control to a second reproduction speed; rotating the disk by means for rotating the disk; turning off the focus servo control means by the switch means; Is applied to the focus actuator section by means of applying Applies a voltage that changes linearly, and inputs the focus error signal output from the focus error detection means to the means for detecting the amount of surface deviation of the disk, and performs the switching in accordance with the surface deviation information obtained. Controlling the means to set the playback speed of the disc to the first playback speed,
Alternatively, an optical disk device that controls switching to a second reproduction speed. 2. The optical disk device according to claim 1, wherein the means for detecting the surface runout comprises: a time generating means for detecting and outputting a time required for one rotation of the disk; and a focus error detecting means. Counting means for counting the number of focus error S-shaped waveform signals to be output, the time required for one rotation of the disk obtained by the time generating means, and the focus actuator when the count result of the counting means changes. Data storage means for storing data corresponding to the voltage value applied to the unit, and data processing for calculating a surface runout of the disk by performing a predetermined process based on the data stored in the data storage means Means for calculating the number of focus error S-shaped waveform signals output from the focus error detection means for one rotation of the disk. An optical disc characterized by calculating the amount of surface deflection of the disc by performing a predetermined process on data corresponding to the voltage value applied to the focus actuator unit at the time when the counted result changes during the interim period apparatus. 3. A means for rotating a disk, a tracking error detection means for detecting a tracking error signal, a focus servo control means for performing focus control on the disk, and a tracking servo for performing tracking control on the disk. Control means, switch means for turning on / off the operation of the tracking servo control means, means for detecting the amount of eccentricity of the disk, and setting the reproduction speed of the disk to a first reproduction speed or a value higher than the first reproduction speed. An optical disc apparatus comprising: a switching control means for performing switching control to a small second reproduction speed, wherein the disc is rotated by means for rotating the disc, the focus servo control is performed by the focus servo control means, and the tracking servo control means is provided. Is turned off by the switch means, and the tracking The tracking error signal output from the detection means is input to the means for detecting the amount of eccentricity of the disk, and the switching means is controlled in accordance with the eccentricity information to obtain the reproduction speed of the disk at the first reproduction speed. ,
Alternatively, an optical disk device that controls switching to a second reproduction speed. 4. The optical disk device according to claim 2, wherein the means for detecting the amount of eccentricity includes a time generating means for detecting and outputting a time required for one rotation of the disk, and a time generating means for detecting the amount of eccentricity with the tracking control turned off. Counting means for counting the number of track crossing signals output from the tracking error detecting means, the time required for one rotation of the disk obtained by the time generating means, and data obtained by the counting means. Data processing means for calculating the amount of eccentricity of the disk by performing a predetermined process to
The number of track crossing signals output from the tracking error detecting means is determined by the time required for one rotation of the disk.
An optical disc device, wherein a predetermined process is performed on the counted result to calculate a surface runout of the disc.