JP2000207758A - Optical disk controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical disk controller which increases the accuracy of a feedforward control operation and reduces the burden on a feedback control operation when a track servo control operation is performed, by combining the feedforward control operation with the feedback control operation, and which can deal with a high-speed rotation. SOLUTION: Even when a situation that the rotational speed of an optical disk 1 is different in case a signal for a feedforward control operation is obtained and in an actual control operation, the gain of an amplifier 11 with reference to a signal for feedforward control to be outputted from a memory 5 is adjusted by a gain adjusting means 10 in the actual control operation, and the accuracy of the feedforward control operation is enhanced. As a result, the burden of a feedback control operation is reduced, and the track servo control operation of the optical disk 1 in a high-speed rotation can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk control device for performing track servo control by a combination of feedforward control and feedback control.

[0002]

2. Description of the Related Art As one of methods for realizing track servo in a high-density, high-speed optical disk apparatus, there is a method utilizing feedforward control in addition to feedback control.

FIG. 7 shows a configuration example for track servo control by this method. First, an objective lens (not shown) is mounted on an optical pickup (not shown) such that an objective lens (not shown) faces the optical disc 1 rotated and driven by a spindle motor (not shown). The optical pickup is mounted on a carriage and is capable of performing seek movement in the radial direction of the optical disc 1. Further, an actuator 2 for displacing and driving the objective lens in a direction perpendicular to the track (radial direction) of the optical disk is mounted in the optical pickup. The drive signal for the actuator 2 is output from the driver 3. Also, a DSP (digital signal) for outputting a signal for controlling the actuator 2 so that the spot follows the target track from a tracking error signal TE indicating the amount of deviation of the spot on the optical disc from the track detected by the push-pull method. (Processor) 4 is provided. Reference numeral 5 denotes a memory, which holds data for controlling the actuator 2 in accordance with the amount of eccentricity of the disk for one round of the optical disk 1. Further, an eccentric component detector 6 is provided which extracts a signal of an eccentric component of the optical disk 1 from a drive signal of the actuator 2, generates data for driving the actuator 2 in accordance with the eccentricity of the disk, and stores the generated data in the memory 5. I have. Further, there is provided an adder 7 for adding the signal from the DSP 4 and the data from the memory 5 and outputting the result to the actuator 2. A switch SW1 such as an analog switch is interposed between the adder 7 and the memory 5, and
A switch SW1 such as an analog switch is interposed between the eccentric component detection unit 6 and the eccentric component detection unit 6. As a result, a feedback control system 8 is formed by a loop of the actuator 2, the DSP 4, the adder 7, the driver 3, and the actuator 2, and a feed forward control system 9 is formed by a system of the memory 5, the adder 7, the driver 3, and the actuator 2. Have been.

In such a configuration, first, when the optical disk 1 is set on the turntable, the switch S
The optical disc 1 is rotated at a low speed by the spindle motor with both W1 and SW2 turned off, and the track servo is applied only by the control of the feedback control system 8.
Next, the switch SW2 is turned on, and the drive signal of the actuator 2 is fetched by the eccentric component detector 6, and the signal of the rotational frequency component of the optical disc 1 is detected from this signal. The detected signal represents the amount of eccentricity of the optical disk 1, and is used to generate a drive signal such that the actuator 2 follows the eccentricity of the optical disk 1 when the optical disk 1 is actually rotated at a high speed. Data is calculated and stored in the memory 5.

Subsequently, during actual recording or reproducing operation, track servo is applied while rotating the optical disc 1 at a high speed by the spindle motor. At this time, the switch SW2 is turned off and the switch SW1 is turned on. Therefore, the actuator 2 uses the data from the memory 5 and the DSP
4 is driven based on the signal obtained by adding the signal from the adder 4 with the adder 7. Here, the data from the memory 5 is used together for feedforward control.

As described above, the feedforward control in which the eccentricity of the optical disk 1 is checked in advance and the actuator 2 is driven and controlled based on the eccentricity, and the drive of the actuator 2 is controlled based on the tracking error signal TE indicating the actual deviation of the spot from the track. The track servo control of the actuator 2 is performed in combination with the feedback control. According to this, track servo can be applied without having to increase the servo band in feedback control in order to cope with high-speed rotation.

[0007]

However, the data used in the feedforward control is obtained by calculation from the drive signal of the actuator 2 at the time of low-speed rotation, and this is the optical disk at the time of high-speed rotation during actual recording or reproduction. It is difficult to accurately follow the eccentricity of 1 and it will be slightly out of alignment. The larger the amount of the deviation, the greater the burden of the feedback control, the less the advantage of using the feedforward control together, and the more difficult it is to cope with high-speed rotation. That is, the accuracy of the actual feedforward control is low.

[0008] In the case of an optical disk apparatus having a reproducing system and a recording system corresponding to a writable optical disk, generally, the rotation speed of the optical disk is different between the time of reproduction and the time of recording. It is necessary to have a memory for reproduction and a memory for recording as the memory 5 for securing, and to switch between the time of reproduction and the time of recording. Furthermore, in the case of a CLV (constant linear velocity) operation method in which the rotation speed is changed depending on the radial position of the optical disc 1, it is required that the system can cope with the change in the rotation speed, but this point is not particularly considered. .

Accordingly, the present invention provides an optical disc capable of coping with high-speed rotation by increasing the accuracy of feedforward control and reducing the load of feedback control in performing track servo control by a combination of feedforward control and feedback control. It is an object to provide a control device.

Another object of the present invention is to provide an optical disk control apparatus capable of coping with recording and reproduction with a small amount of memory for feedforward control when a recording system and a reproduction system having different rotation speeds of an optical disk are provided. Aim.

A further object of the present invention is to provide an optical disk control apparatus capable of performing track servo by feedforward control capable of coping with a CLV operation in which a rotation speed is changed according to a radial position of an optical disk.

[0012]

According to the first aspect of the present invention,
An optical disk control device that performs track servo control by a combination of feedforward control and feedback control includes a gain adjustment unit that adjusts the gain of a signal on the feedforward control side.

Therefore, even if the rotation speed of the optical disk differs between the case where the signal for the feedforward control is obtained and the time of the actual control, the signal for the feedforward control is obtained by the gain adjusting means during the actual control. By adjusting the gain, the accuracy can be improved, so that the load of the feedback control can be reduced and the track servo of the high-speed rotating optical disk can be performed.

According to a second aspect of the present invention, in an optical disk control device having a recording system and a reproducing system and performing track servo control by a combination of feed forward control and feedback control, the gain of the signal on the feed forward control side is reduced. There is provided a gain adjusting means for adjusting.

Therefore, the present invention is basically the same as the first aspect of the present invention. In particular, even if the optical disk has a recording system and a reproducing system and the rotation speeds of the optical disks are different, the recording system and the reproducing system can be used. By changing the gain by sharing the signal for the feedforward control with the signal for the reproduction, it is possible to easily and properly cope with it, and it is not necessary to increase the memory.

According to a third aspect of the present invention, in the optical disk control device according to the first or second aspect, the gain adjusting means adjusts a gain according to a rotation speed of a spindle motor for rotating the optical disk.

Accordingly, in realizing the first or second aspect of the present invention, even if the rotation speed of the optical disk changes, the gain of the signal for the feedforward control can be easily and appropriately adjusted by adjusting the gain accordingly. , CLV operation method.

According to a fourth aspect of the present invention, in the optical disk control device according to the third aspect, the gain adjusting means outputs at a frequency corresponding to the rotation speed of a variable gain amplifier and a spindle motor for rotating the optical disk. Speed detecting means for detecting a rotation speed of the optical disk based on an FG signal; and setting means for setting a gain of the amplifier according to the detected rotation speed.

Therefore, the invention according to claim 3 can be easily realized by detecting the rotation speed using the FG signal output from the spindle motor.

According to a fifth aspect of the present invention, in the optical disk control device according to the first or second aspect, the gain adjusting means includes a variable gain amplifier and a rotational speed of the optical disk based on a wobble signal read from the optical disk. And a setting means for setting the gain of the amplifier according to the detected rotation speed.

Therefore, the invention according to claim 1 or 2 can be easily realized by detecting the rotation speed using the wobble signal read from the optical disk.

[0022]

FIG. 1 shows a first embodiment of the present invention.
A description will be given with reference to FIG. The same parts as those shown in FIG. 7 are denoted by the same reference numerals, and description thereof is omitted (the same applies to the following embodiments). In the present embodiment, a gain adjusting means 10 is added to the feedforward control system 9. The gain adjusting means 10 includes a memory 5
The amplifier 11 includes a variable gain amplifier 11 interposed between the adders 7 and a gain adjustment unit 12 that varies the gain of the amplifier 11 based on the tracking error signal TE. Thus, the gain of the feedforward data signal output from the memory 5 to the adder 7 is increased by the amplifier 11.
It can be changed as needed. here,
It is assumed that data corresponding to high-speed rotation is stored in the memory 5 based on the detection of the amount of eccentricity by the eccentricity component detection unit 6 by low-speed rotation driving as in the case described with reference to FIG.

A method of actually applying high-speed track servo by rotating the optical disk 1 at a high speed by a spindle motor in such a configuration will be described. First, when the tracking error signal TE is observed while the optical disc 1 is rotated and only the focus servo control is performed, the light spot crosses the track due to the eccentricity of the optical disc 1 as shown in FIG. A tracking error signal TE having a waveform as shown in FIG. Under such circumstances, only the switch SW1 is turned on and the memory 5 is turned on.
Only feedforward control using the data stored in is performed. At this time, the gain of the amplifier 11 is set to 1.

In this case, if the drive signal of the actuator 2 obtained from the memory 5 can completely follow the eccentricity of the optical disk 1, the light spot does not cross the track as shown in FIG. , FIG.
A linear tracking error signal T as shown in FIG.
E is obtained. However, since the track cannot actually completely follow the track (see FIG. 4A), a tracking error signal TE having a waveform as shown in FIG. 4B is obtained. Therefore, by appropriately adjusting the gain of the amplifier 11 by the gain adjusting unit 12, the deviation from the track due to the feedforward control can be reduced. That is, since the accuracy of the feedforward control is improved, the load due to the feedback control can be reduced and appropriate track servo control can be performed.

FIG. 5 shows an example of the configuration of the gain adjustment section 12 for such gain adjustment. First, actuator 2
A binarization unit 13 is provided for binarizing the tracking error signal TE input from the side and generating a pulse signal. A counter 14 is provided for counting the number of pulses at the rise or fall of the pulse signal binarized by the binarization unit 13. The counter 14 is reset every time the optical disc 1 makes one rotation, so that the number of tracks crossed by the light spot in one rotation is counted. The gain control unit 15 to which the count value from the counter 14 is input sets the gain of the amplifier 11 so that the count value becomes the smallest, that is, the number of tracks traversed by the light spot is reduced. If the gain of the amplifier 11 can be set to minimize the amount of deviation due to the feedforward control, the feedback control is turned on with the gain setting to perform the actual track servo. As a result, the accuracy of the feedforward control can be improved, and the track servo can be appropriately applied to the optical disc 1 rotating at a higher speed without increasing the servo band of the feedback control.

By the way, in the case of an optical disk apparatus for a writable optical disk 1 having both a recording system and a reproduction system, the rotation speed of the optical disk 1 generally differs between recording and reproduction. Thus, even when the rotation speed of the optical disc 1 varies depending on the operation mode, it is not necessary to store data in separate memories, and the memory 5 stores only data corresponding to the rotation speed during reproduction, or Conversely, only the data corresponding to the rotation speed at the time of recording is held, and the gain of the amplifier 11 is adjusted and set by the gain adjustment unit 12 in accordance with the rotation speed of each operation mode. Track servo control with high-precision feedforward control suitable for the control can be performed.

Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, the optical disc 1
This is an example in which the feedforward control is properly performed in the case of a CLV operation type optical disk device in which the rotational speed is changed according to the radial position to rotate the optical disk. For this reason, the gain adjusting means 10 of the present embodiment adjusts the rotation speed of the optical disc 1 based on the FG signal (signal generated based on an encoder provided on the spindle motor shaft) output from the spindle motor for rotating the optical disc 1. A rotation speed detection unit 16 is a speed detection unit for detecting the rotation speed, and a gain setting unit 17 is a setting unit that sets the gain of the amplifier 11 according to the rotation speed detected by the rotation speed detection unit 16. . That is, the rotation speed detector 1
Numeral 6 detects the rotation speed of the optical disk 1 from the FG signal output from the spindle motor and outputs a signal proportional to the rotation speed. The gain setting unit 17 variably sets the gain of the amplifier 11 based on this signal.

Thus, even if the rotation speed of the optical disk 1 changes due to the CLV operation, the track servo can be applied together with the feedback control without impairing the accuracy of the feedforward control.

Incidentally, depending on the optical disk 1, for example,
A signal for rotation control or the like is formed as a track by a groove that has been wobbled (meandering) in advance, and there is a type in which address information is recorded by modulating the wobble signal. Alternatively, the rotation speed detector 16 for detecting the rotation speed of the optical disk 1 may detect the rotation speed from the wobble signal read from the optical disk 1 and output a signal proportional to the rotation speed.

[0030]

According to the first aspect of the present invention, even if the rotation speed of the optical disk is different between the case where the signal for feedforward control is obtained and the time of actual control, the actual control is not performed. Since the gain of the signal for the feedforward control is adjusted by the gain adjusting means, the accuracy of the feedforward control can be improved. Can be done.

According to the second aspect of the invention, basically the same effects as those of the first aspect of the invention can be obtained. However, in particular, a recording system and a reproduction system are provided, and the rotation speeds of the optical disks are different. Even in such a situation, it is possible to easily and appropriately cope with the signal for recording and reproduction by sharing the signal for feedforward control and changing the gain without increasing the memory.

According to the third aspect of the present invention, in realizing the first or second aspect of the present invention, even if the rotation speed of the optical disk changes, the gain of the signal for feedforward control is adjusted accordingly. Thus, it is possible to easily and appropriately deal with the problem, and to easily apply to the CLV operation method.

According to the fourth aspect of the present invention, the rotation speed is detected using the FG signal output at a frequency corresponding to the rotation speed of the spindle motor, thereby easily realizing the third aspect of the invention. be able to.

According to the fifth aspect of the present invention, the invention according to the first or second aspect can be easily realized by detecting the rotation speed using the wobble signal read from the optical disk.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram when only focus servo control is performed.

FIG. 3 is an explanatory diagram of a case where a light spot ideally follows.

FIG. 4 is an explanatory diagram in the case of actual control.

FIG. 5 is a block diagram illustrating a configuration example of a gain adjustment unit.

FIG. 6 is a block diagram showing a second embodiment of the present invention.

FIG. 7 is a block diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 10 Gain adjustment means 11 Amplifier 16 Speed detection means 17 Setting means

Claims (5)

[Claims] 1. An optical disc control apparatus for performing track servo control by a combination of feedforward control and feedback control, comprising: a gain adjustment means for adjusting a gain of a signal on a feedforward control side. 2. An optical disk control device having a recording system and a reproduction system and performing track servo control by a combination of feedforward control and feedback control.
An optical disc control device, comprising: a gain adjusting means for adjusting a gain of a signal on a feed forward control side. 3. The optical disk control device according to claim 1, wherein said gain adjusting means adjusts a gain according to a rotation speed of a spindle motor for rotating the optical disk. 4. The gain adjusting means includes: a gain-variable amplifier; and a speed detecting means for detecting a rotation speed of the optical disk based on an FG signal output at a frequency corresponding to a rotation speed of a spindle motor for rotating the optical disk. Setting means for setting the gain of the amplifier according to the detected rotation speed.
An optical disk control device as described in the above. 5. The gain adjusting means includes: a gain-variable amplifier; a speed detecting means for detecting a rotation speed of the optical disk based on a wobble signal read from the optical disk; 3. The optical disk control device according to claim 1, further comprising setting means for setting a gain of the amplifier.