JP2735037B2 - Optical disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk drive, and more particularly to a method for controlling the position of a positioner of an optical disk drive.
The present invention relates to an optical disc device that removes an offset in a radial driving speed based on a thrust difference depending on a driving direction of a driving device by a digital processing circuit such as an SP (Digital Signal Processor).

2. Description of the Related Art In an optical disk device, the offset of the thrust of a positioner due to a driving direction can always occur due to a spring effect of an electric wire or the like connected to an optical head.

In an optical disk device, if there is an offset in the thrust of a positioner that drives the optical head in the radial direction (inner and outer directions) of the optical disk, the performance of the optical disk device is reduced. The method and the apparatus for removing the offset are required.

[0004]

2. Description of the Related Art Conventionally, as a countermeasure against an offset of a positioner thrust in an optical disk apparatus, instead of removing the offset itself, a thruster offset of a positioner is determined in advance based on design data of a positioner or statistical data of a positioner thrust inspection. A method of estimating the range and restricting the use conditions such as the inclination of the device based on the estimated value or restricting the device control conditions such as the track seek has been adopted.

In Japanese Patent Laid-Open Publication No. Hei 1-300431, when a specific track of an optical disc is selected and a signal corresponding to the position of the track is output, the level corresponding to the level of the low frequency component of the tracking error detection signal is adjusted. It describes that the offset of the tracking control is prevented by correcting the signal corresponding to the track position by using the obtained signal. However, such a method cannot remove the offset of the positioner thrust.

In Japanese Patent Laid-Open Publication No. Hei 2-15428, an arithmetic circuit determines an offset equivalent of a tracking error signal based on an output of a displacement sensor and subtracts the offset from the tracking error detection signal.
It describes that the offset of the tracking error signal is removed. However, such a method cannot remove the offset of the positioner thrust.

[0007]

In the conventional offset removal method for an optical disk device, the offset itself is not removed, so that the performance of the optical disk device itself is reduced.
There is a problem that it becomes worse as compared with a state where there is no offset.

In addition, since the check of the offset amount is only performed at the time of inspection before shipment, in the case of an optical disk device whose offset amount is just below the inspection standard, the offset amount becomes excessive due to the aging of the offset, and the device performance becomes poor. There is a problem that the device may not only be further deteriorated, but also may be damaged in the worst case.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to solve the disadvantages of the prior art and, in particular, to provide a mechanical and electrical off of the positioner.
Offset of thrust in one direction and thrust in other direction by setting
It is an object of the present invention to provide an optical disc device capable of calculating an amount for removing an offset and removing an offset caused by the positioner .

[0010]

SUMMARY OF THE INVENTION An offset removing method and apparatus for an optical disk device according to the present invention has the following configuration in order to solve the above-mentioned problems of the prior art.

(1) An optical head having a condenser lens for forming a beam spot on a recording layer of an optical disk by a laser beam, and condenser lens position control means for controlling the positioning of the condenser lens; An optical head positioning unit for moving the head in the radial direction of the optical disk. In addition, the optical head positioning unit counts the positioner that drives the optical head and the number of tracks that the beam spot traverses while the optical head moves in one direction for a predetermined period of time by driving the positioner. First
And a second counter for counting the number of tracks crossed by the beam spot while the optical head section moves for the same period of time as the certain period of time from the end position after the completion of the certain period of time in the direction opposite to one direction from the end position. And a compensation value for calculating a value obtained by multiplying a difference between the count value of the forward pass from the first counter and the count value of the return pass from the second counter by a constant coefficient as a compensation value for the positioner operation. And part.

(2) In the case of (1), the compensation value calculation unit is provided with a positioner control unit for controlling the operation of the positioner for each driving direction based on the compensation value from the compensation value calculation unit.

(3) In the case of (1), the optical head positioning unit includes a first constant voltage generating circuit for supplying a constant voltage to the positioner for a predetermined constant time, and the first constant voltage generating circuit. And a second constant voltage generating circuit for supplying a constant voltage having the same polarity and the same magnitude as that of the first constant voltage generating circuit to the positioner for a fixed time after the supply of the constant voltage is completed.

[0014]

According to the offset removing method of the present invention, first, the condensing lens is made to follow the track groove at the position opposite to the direction in which the head is to be moved first. Switch to inspection signal. A constant voltage value is output as a test signal for a certain period of time, and while the positioner is operating by the test signal, the track count value that has been counted is held. Return to.

From this state, a constant voltage value is output again as a test signal for a predetermined time. However, the output at this time has the opposite polarity and the same magnitude as the previous output, and the positioner moves in the direction opposite to the previous movement. The count value at this time is held, and a difference from the first held count value is calculated.

Since the count value at this time is proportional to the amount of movement of the optical head, an offset value of the positioner thrust can be obtained by multiplying this count difference by a constant coefficient. Is added to the positioner input in the movement direction in which is smaller, finally the offset can be almost completely removed from the positioner thrust.

When the offset is removed by the method of the present invention, it is necessary to control so that the direction of movement of the positioner when adding a value obtained by multiplying the count difference by a constant coefficient to the positioner input is always the same.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. FIG. 1 is a control block diagram of the embodiment, and FIG. 2 is a time chart showing waveforms of main signal lines in the embodiment. FIG. 3 is an explanatory diagram showing a relationship between a laser beam spot position and a track difference signal and a track sum signal. FIG. 4 shows a positional shift between the optical head unit 12 and the optical axis of the condenser lens 5. FIG. 5 is a diagram showing a relationship between the output of the lens position detector 2 and the output of the lens position detector 2.

As shown in FIG. 1, the optical disc apparatus includes a condenser lens 5 for forming a beam spot on a recording layer of the optical disc 100 by a laser beam, and a condenser lens position control for controlling the positioning of the condenser lens 5. Optical head unit 12 having tracking actuator 9 as means
It has. The optical head unit 12 is provided with an optical head positioning unit (not shown) for roughly positioning the optical head unit 12 in the radial direction of the optical disc 100.

In addition, the optical head positioning section includes a positioner for driving the optical head, and a track for which the beam spot crosses while the optical head section moves in one direction for a predetermined period of time by driving the positioner. A first counter 103 for counting the number of tracks, and counting the number of tracks crossed by the beam spot while the optical head moves for a certain time in a direction opposite to one direction from the position where the end has ended after a certain time. A second counter 105, and an illustration of calculating a value obtained by multiplying a difference between the count number of the forward path from the first counter 103 and the count number of the return path from the second counter 105 by a constant coefficient as a compensation value. And a compensation value calculator that does not perform the calculation. In the present embodiment, the multiplier 110 and the comparator 104 constitute a compensation value calculation unit.

Next, the operation will be described. After the laser light emitted from the laser light source 3 passes through the beam splitter 4,
The light is reflected by the half mirror 8 and is condensed on the recording layer (not shown) of the optical disc 100 by the condenser lens 5.
The laser light reflected by the recording layer has an optical path opposite to that at the time of incidence,
The light returns to the beam splitter 4, where it is reflected and guided to the track position detector 1.

In accordance with the output from the track position detector 1, the track difference signal generating amplifier 6 and the track sum signal generating amplifier 7 generate a track difference signal and a track sum signal, respectively. Here, the track difference signal is
The track sum signal is a signal generated by the difference between the outputs from the two optical sensors of the track position detector 1, and the track sum signal is a signal generated by the sum of the outputs from the two optical sensors of the track position detector 1. .

As shown in FIG. 3, when the beam spot based on the laser beam is at the center 31 of the track groove, the track difference signal becomes zero and the track sum signal becomes the maximum value. When the beam spot is located at the position of the edge 32 of the track groove, the track difference signal becomes the maximum value, and the track sum signal becomes zero. When the beam spot is located at the edge 33 of the opposite groove, the track difference signal becomes the minimum value. , The track sum signal becomes zero.

The focusing lens 5 is driven by the tracking actuator 9 in the radial direction of the optical disc 100 within a range of a movement amount of about 100 microns.

In the present invention, first, the position of the beam spot with respect to the track groove is controlled. In this position control, the track difference signal is output to the tracking actuator 9 via the filter 10 and the switch 11, and the feedback control is performed so that the track difference signal becomes 0, so that the beam spot is located at the center of the track groove. It is controlled to be located. In this case, the filter 10
This is provided to stabilize feedback control for the secondary delay characteristic of the actuator 9, and a lead-lag filter is generally used.

As described above, the tracking actuator 9 controls the movement amount of about 100 microns or less, whereas the recording area of the optical disk medium has a length of several centimeters to several tens of centimeters. As a method of controlling the movement, it is general that the movement is controlled by a positioner 17 provided in the optical head unit 12.

There are various methods of controlling the positioner. In this embodiment, the most general method among them, the lens position following control, is used. In this method, as shown in FIG. 4, the relative position deviation between the optical axis of the condenser lens 5 and the optical head unit 12 from the lens position detector 2 for detecting the transmitted light of the half mirror 8 is determined. The position of the optical head unit 12 is controlled by outputting an output that changes according to the output to the positioner 17 via the filter 14 and the switch 15 and performing feedback control so that the output from the lens position detector 2 becomes zero. This is widely used as a position control method for a magneto-optical disk.

The filter 14 used at this time is provided for the same purpose as the filter 10 described above. The switch 11 and the switch 15 are configured to be switched according to an instruction from the MPU 18.

In this embodiment, in order to remove the offset of the current flowing through the positioner 17, first, the MPU 1
8, the switch 11 is connected to the output side of the filter 14, and the switch 15 is connected to the first constant voltage generation circuit 101. By this switching, the positioner 17 moves at a constant speed, and the condenser lens 5 is held at the neutral point.

At the same time, the switch 102 is connected to the first track counter 103. Switch 1
02 is connected to a signal obtained by binarizing the output of the track difference signal generation amplifier 6 by the comparator 104, and is guided to the first track counter 103 by switching of the switch 102.

After a fixed time t, the MPU 18
Is connected to the filter 14 again, and the switch 11 is connected to the filter 10 to perform position control.
Cut 2

Next, the MPU 18 connects the switch 11 to the output side of the filter 14, connects the switch 15 to the second constant voltage generating circuit 106, and connects the switch 102 to the second track counter 105. From the second constant voltage generation circuit 106, a signal having the same magnitude and opposite polarity as the output of the first constant voltage generation circuit 101 is output.

Further, by this switching, the positioner 17 moves at a constant speed in a direction opposite to that at the time of the above-mentioned constant speed movement. Also in the case of the constant speed movement, the MPU 18 connects the switch 15 to the filter 14 and the switch 11 to the filter 10 after the elapse of the same time t as that at the time of the above-described constant speed movement, performs the position control, Disconnect.

At the same time as this switching, the switch 107 is closed, and the D / A converter 108 and the adding circuit 16 are connected. The subtractor 109 subtracts the count value of the track counter 105 from the count value of the second track counter 105, and the multiplier 110 multiplies the subtraction result by a constant coefficient. The D / A converter 108 converts this multiplication result into an analog signal and outputs it.

In this manner, in FIG. 2, the count value of the forward path is accumulated in the first counter 103 by the first constant speed movement of the positioner 17, and then the constant speed movement of the positioner 17 in the reverse direction is performed. By movement, the second
Of the return path is accumulated in the counter 105, and the count value accumulated in the counter during this time is thereafter retained and always reflected on the output of the D / A converter 108.

The offset value is removed from the thrust of the positioner 17 by adding the difference between the count values of the two counters to the output of the lens position detector 2 when the switch 107 is closed last. After the implementation of the example method, offsets due to the positioner 17 are canceled in the outputs of the lens position detector 13 and the filter 14.

The operation of obtaining a compensation value obtained by multiplying the difference between the count values of the two counters by a constant constant by driving the positioner at a constant voltage is performed at the time of starting the apparatus or periodically or irregularly based on the control of the processing apparatus. The compensation value may be periodically stored, and the compensation value may be stored and added to the positioner input in one direction, that is, in the movement direction in which the count value decreases when the positioner follows control.

This compensation value may be stored separately in a storage device of the processing device or the like, or the counters 103 and 105 may be stored in a counter that does not lose its stored contents even when the power is turned off. It can also be configured and stored in this.

[0039]

As described above, according to the present invention, the compensation value calculation section determines the difference between the forward count from the first counter and the return count from the second counter by a constant coefficient. Is calculated as the compensation value.
Mechanical and electrical thrust in one direction and thrust in the other direction
If there is a significant offset, this can be quantitatively detected, and furthermore, since the positioner is driven by compensating with this compensation value, the offset can be reliably removed, and therefore the performance can be reduced. It is possible to provide an unprecedented excellent optical disk device which can improve the condition and can eliminate the limitation on the inclination as a device use condition and the limitation on device control such as track seek.

[Brief description of the drawings]

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

FIG. 2 is a time chart showing waveforms of main signal lines in the embodiment of FIG.

FIG. 3 is an explanatory diagram showing a relationship between a laser beam spot position, a track difference signal, and a track sum signal.

FIG. 4 is a diagram showing a relationship between a displacement between the optical head unit 12 and the condenser lens 5 and an output of the lens position detector 2.

[Explanation of symbols]

 5 Condensing lens 12 Optical head unit 17 Positioner 100 Optical disk 101 Constant voltage generation circuit 103 Counter 105 Counter 106 Constant voltage generation circuit

Claims (3)

(57) [Claims] 1. A and the optical head having a condensing lens position control means for controlling the positioning of the condenser lens and the condenser lens with a laser beam to form a beam spot on the recording layer of the optical disc, the optical head section in the optical disk apparatus having an optical head positioning unit which moves in the radial direction of the optical disk, the optical head positioning portion, and a positioner for driving the optical head, the optical head section to a predetermined fixed time the one-way A first counter for counting the number of tracks traversed by the beam spot during the movement of the beam spot, and after the end of the fixed time, from the position where the beam spot has ended in the opposite direction to the one direction for the same time as the fixed time A second counter for counting the number of tracks traversed by the beam spot while the optical head is moving; A compensation value calculation unit that calculates a value obtained by multiplying a difference between the count number of the forward path from the counter and the count number of the return path from the second counter by a constant coefficient as the compensation value for driving the positioner. Characteristic optical disk device. 2. A method for controlling the operation of the positioner based on a compensation value from the compensation value calculating unit.
2. The optical disk device according to claim 1, further comprising a positioner control unit for controlling the direction . 3. A first constant voltage generating circuit, wherein the optical head positioning section supplies a constant voltage to the positioner for a predetermined constant time, and the supply of the constant voltage by the first constant voltage generating circuit ends. And a second constant voltage generation circuit for supplying a constant voltage having the same polarity and the same magnitude as that of the first constant voltage generation circuit to the positioner for a predetermined period of time after the operation. An optical disk device as described in the above.