JPH0721573A - Optical disk device - Google Patents

Abstract

PURPOSE:To improve the accuracy and stability of a track jump operation. CONSTITUTION:This device is provided with a tracking actuator 1T for moving an objective lens 1A of an optical head 1 in the radial direction of an optical disk, lens position detecting means 2 for detecting the position of this objective lens 1A, and pulse generation control means 30 for generating a first pulse and a second pulse following this first pulse and for outputting this first or second pulse while controlling the pulse width or amplitude corresponding to the output of this lens position detecting means 2. When performing track jump, this tracking actuator 1T is driven corresponding to the two outputs of this pulse generation control means 30. Even when the information track of the optical disk is considerably vibrated, the track jump is extremely stably performed as a result, seek time is shortened, and seek error is hardly generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc device, and more particularly to a track jump device for moving a light spot to another information track during recording or reproduction.

[0002]

2. Description of the Related Art An outline of a conventional optical disk device will be described below with reference to FIGS. FIG. 5 is a block diagram showing a main part of a conventional optical disc device. Figure 7
It is a figure which shows the structural example of the optical head in the conventional optical disk apparatus. An optical disc used in the optical disc device shown in FIG. 5 has spiral information tracks formed of information pit rows like a compact disc for music. In the optical head 10, laser light is emitted from a laser light source fixed to the optical system base 1K, the laser light is condensed by the objective lens 1A, and is irradiated in a light spot shape on a target position on the optical disc. Information is read from the reflected light from the optical disc by the 4-division photodetector 1L. The optical head 10 is composed of an optical system and a drive system.

The optical system is a mechanism for focusing laser light on a disk medium and detecting a deviation between a laser light spot and a target position on the disk medium.
It is composed of a laser light source, lenses, a beam splitter, a photodiode, etc., and is fixed to the optical system base 1K except for the objective lens 1A. The drive system moves the objective lens 1A in a direction perpendicular to the surface of the optical disc to control the laser light to form a spot on the disc medium, and moves the objective lens 1A in the radial direction of the optical disc. Tracking control is performed to make the optical spot follow the deflection of the track so that the optical spot scans on the center line of the information track, and the target position on the disk medium and the laser beam spot are placed in a predetermined relationship. It is a drive mechanism for maintaining and is generally called an actuator.

The actuator comprises a tracking actuator for performing tracking control and a focus actuator for performing focus control. The tracking actuator 1T includes a tracking coil 1B, a permanent magnet 1C, a yoke 1Y made of a magnetic material magnetically coupled to the permanent magnet, and the like, whereby the objective lens 1A is moved in the direction of arrow TR. . The focus actuator is composed of a focusing coil 1J, a permanent magnet 1C, a yoke 1Y, etc., which moves the objective lens 1A in the direction of arrow FC. The objective lens 1A, the tracking coil 1B, and the focusing coil 1J are fixed to a bobbin 1E, and the bobbin 1E is locked to an actuator base 1M via a movable part supporting suspension 1G composed of four leaf springs. ing.

The permanent magnet 1C is fixed to the actuator base 1M, and the actuator base 1M is fixed to the optical system base 1K. In the tracking control, the tracking actuator is driven based on the tracking error signal i2 obtained by the tracking error detection circuit 7A, and the objective lens 1A
Are moved parallel to the plane of the disk medium and in its radial direction. In FIG. 5, the tracking control means 7 comprises the tracking error detection circuit 7A and a phase compensation circuit 12 for stabilizing the operation of the tracking control loop, and the tracking error signal i2 is applied to the phase compensation circuit 12. , Its output g2 is applied to the actuator drive circuit 5 via the switch 8.

The actuator drive circuit 5 drives the tracking actuator, and its output is applied to the tracking coil 1B. By the way, in the optical disk device, a track jump is performed to guide the light beam to the information track to be accessed. This track jump is performed by moving the objective lens 1A in the radial direction of the optical disc. The movement of the objective lens 1A is performed by the output f2 of the pulse generating means 3, and the pulse generating means 3 is composed of an acceleration pulse generating circuit 14, a deceleration pulse generating circuit 15, a subtractor 13, a direction setting circuit 16 and the like. There is. The acceleration pulse generation circuit 14 generates a first pulse having a predetermined pulse width T1 under the control of the MPU 6 at the time of the track jump,
In the deceleration pulse generation circuit 15, a second pulse having a pulse width T2 is generated following the first pulse. The pulse width T2 of the second pulse is the same as the pulse width T1 of the first pulse, and the amplitudes of both pulses are equal.

In the subtracter 13, the output b2 of the deceleration pulse generating circuit 15 is subtracted from the output a2 of the acceleration pulse generating circuit 14 and the result is applied to the direction setting circuit 16 determined by the signal c2. In the direction setting circuit 16, the polarity of the signal c2 is inverted under the control of the MPU 6 according to the track jump direction, and the resulting signal f2 is applied to the actuator drive circuit 5 via the switch 8. The switch 8 is controlled by the MPU 6, and the signal h2 at its output terminal becomes the signal f2 only when the track jump is performed, and becomes the signal g2 at other times.

Next, the operation of the optical disk device shown in FIG. 5 will be described. When a track jump is performed in the optical disk device, the instruction is given from the MPU 6 to the acceleration pulse generation circuit 14, the direction setting circuit 16, and the switch 8. The pulse width of the first pulse generated by the acceleration pulse generation circuit 14 in response to the instruction from the MPU 6 is instructed by the MPU 6 to be a predetermined value according to the distance (the number of tracks) at which the track jump is performed. Following the first pulse, a second pulse having the same amplitude and pulse width as the first pulse is generated by the deceleration pulse generation circuit 15.

The tracking coil 1B is energized in one direction by the signal corresponding to the first pulse, and is energized in the other direction by the signal corresponding to the second pulse. That is, at the time of the track jump, the objective lens 1A is accelerated in the track jump direction by the signal corresponding to the first pulse, and then decelerated by the signal corresponding to the second pulse, and when the second pulse ends. Then, it is desirable that the light spot is on the center line of the information track and the speed of the objective lens 1A is substantially zero. Figure 6 shows how this track jumps
It will be explained based on. FIG. 6 is a diagram showing signal waveforms at various parts during a track jump in a conventional optical disk device.

In FIG. 6, a jump of one track to an adjacent track is described. In FIG. 6, f2 is the output of the direction setting circuit 16 and i2 is the tracking error detection circuit 7.
A tracking error signal output from A, fp3 is a pulse corresponding to the first pulse in the signal f2, and fp4 is a signal f.
2 shows a pulse corresponding to the second pulse in FIG. In (1) of FIG. 6, the light spot is on the center line of the information track (hereinafter, also referred to as the on-track state) immediately before the track jump is performed, but the neutral point of the objective lens 1A is recorded. Alternatively, an example in which the information track being reproduced is deviated in the same direction as the track jump direction is shown.

The neutral point is the objective lens 1 when the tracking coil 1B is not energized.
It indicates the position where A returns, particularly the position in the radial direction of the optical disc. The main cause of the neutral point deviating from the center line of the information track during recording or reproduction is mainly the eccentricity of the information track and the delay of the operation of the feed mechanism that moves the entire optical head. In the example shown in (1) of FIG. 6, the objective lens 1A is biased by the movable portion supporting suspension 1G in the direction of track jump, and this force is substantially constant during the period Tj in which track jump is performed.

The pulse widths and amplitudes of the first and second pulses are preset so as to have optimum values when the objective lens 1A has no deviation. Therefore, in the case of this example, as shown by P2 in the figure, the light spot has already been moved to the center line of the adjacent track before the second pulse ends, and at this time, the speed of the objective lens is zero. Since it has not fallen, it is clearly overshooting. At the point indicated by P1, the objective lens accelerated by the signal fp3 is moving, but the tracking error signal does not change. This is, for example, approximately 1/4 of the track pitch in the radial direction of the optical disc from the center of the information track. It is just a point away. At the point indicated by P3, the objective lens outputs the signal fp
The resulting speed decelerated in 4 is zero.

On the contrary, in (2) of FIG. 6, the light spot is on the center line of the information track (on-track state) immediately before the track jump is performed, but the neutral point of the objective lens 1A is An example is shown in which the direction is deviated in the direction opposite to the track jump direction. In this case, the objective lens 1A is biased by the movable part support suspension 1G in the direction opposite to the jump direction. Thus, this force is substantially constant during the period Tj when the track jump is performed.

Therefore, in the case of this example, the light spot has not moved to the center line of the adjacent track even at the time when the second pulse ends, and is in an undershoot state. As described above, in the conventional optical disk device, the objective lens 1 is
If a track jump is performed with the neutral point of A deviating from the information track being recorded or reproduced, the movement to the target track can be completed just when the deceleration pulse (second pulse) ends. However, there is a problem that the access time or seek time becomes long, or a so-called seek error occurs in which the light spot cannot be moved to the target track.

[0015]

As described above, in the conventional optical disc apparatus, if a track jump is performed during recording or reproduction of an optical disc having a large information track swing, the target track is not well accessed. There was a problem to say. The present invention has been made in view of the above problems, and an object thereof is to provide an optical disk device capable of performing a favorable track jump operation in recording or reproduction of an optical disk having a large information track swing.

[0016]

The optical disk apparatus of the present invention, when recording or reproducing an optical disk, performs a track jump in which the objective lens of the optical head is moved in the radial direction of the optical disk to move the light spot to a target track. When performing, the amplitude ratio or the pulse width ratio of the pulse for accelerating the objective lens and the pulse for decelerating the objective lens is controlled according to the deviation amount of the objective lens to perform a stable track jump in a short time. Optical disk device. That is, the present invention provides a tracking actuator for moving an objective lens in a radial direction of an optical disc and a lens for detecting a position of the objective lens in an optical disc device for recording or reproducing an optical disc having a circular information track. A position detecting means, a first pulse and a second pulse following the first pulse are generated, and the pulse width or the amplitude of the first pulse or the second pulse is controlled and output according to the output of the lens position detecting means. And a pulse drive control means for driving the tracking actuator, and when performing a track jump,
The optical disk device is configured to control the actuator drive circuit according to two outputs of the pulse generation control means.

[0017]

When the tracking jump is performed, the tracking actuator for moving the objective lens in the radial direction of the optical disk is energized in the opposite directions by the acceleration pulse and the deceleration pulse, and the objective lens is decelerated and then decelerated. For example, when the objective lens is biased by the movable part support suspension in the direction opposite to the track jump direction, the pulse width or amplitude of the acceleration pulse becomes larger than the pulse width or amplitude of the deceleration pulse. As described above, the control is performed according to the output of the lens position detecting means for detecting the position of the objective lens. On the other hand, when the objective lens is biased in the track jumping direction by the movable part supporting suspension, the lens position is adjusted so that the pulse width or amplitude of the acceleration pulse is smaller than the pulse width or amplitude of the deceleration pulse. It is controlled according to the output of the detection means. At the end of the deceleration pulse, the light spot is moved on the center line of the information track, and the speed of the objective lens becomes substantially zero. Therefore, the objective lens is moved without overshoot or undershoot. .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical disk device of the present invention will be described below with reference to FIGS. 1, 2 and 4. FIG. 1 is a block diagram showing a main part of an optical disk device of the present invention. FIG. 2 is a diagram showing an embodiment of the optical disk device of the present invention. Figure 4
FIG. 3 is a diagram showing a configuration example of an optical head according to the present invention. In FIGS. 1, 2, and 4, the same functions and functions as those of FIG. 5 or 7 are designated by the same reference numerals, and the description thereof will be omitted. The optical disc used in the optical disc device shown in FIG. 1 has concentric or spiral information tracks. The optical disc is the same as that used in the conventional optical disc device shown in FIG.

The optical disc device shown in FIG. 1 is different from the conventional optical disc device shown in FIG. 5 mainly in that the lens position detecting means 2 and the pulse generation control means 30 are provided. The pulse generation control means 30 is composed of the pulse generation means 3 and the pulse control means 4. During the track jump, the pulse generation control means 30 is controlled according to the output of the lens position detection means 2, and the tracking actuator 1T is driven according to the output of the pulse generation control means 30. The optical head 1 shown in FIG. 4 corresponds to the conventional optical head 10 shown in FIG.
In comparison with, the lens position sensor light emitting section 1H for detecting the deviation of the objective lens 1A in the radial direction of the optical disc,
The main difference is that the lens position sensor slit 1F and the lens position sensor light receiving portion 1D are provided, and the lens position sensor light receiving portion 1D is composed of a two-divided photodiode.

In FIG. 1, the reflected light from the optical disk is received by the 4-division photodiode 1L of the optical head 1, and the tracking error detecting means 7 is obtained from the output signal thereof.
Then, the tracking error signal is detected and the phase-compensated signal g is supplied to the switch 8. The tracking error signal g whose phase has been compensated is supplied to the actuator drive circuit 5 via the switch 8. Normal tracking control is performed by supplying a current corresponding to the signal g to the tracking actuator 1T of the optical head 1 by the tracking drive circuit 5. On the other hand, when the track jump is performed, the MPU 6 issues a track jump instruction to the switch 8 and the pulse generating means 3.

Then, the switch 8 is switched, and the pulse generating means 3 performs the first pulse having the pulse width T1 for accelerating the objective lens and the subsequent second pulse having the pulse width T2 for decelerating the objective lens. Is generated. The first and second pulses have the same amplitude and pulse width, and the first and second pulses have pulse widths T1 and T2.
MP according to the distance (number of tracks) of the track jump
Instructed by U6. The pulse generator 3 calculates the difference between the first pulse and the second pulse, and the resulting signal is inverted according to the direction of the track jump and supplied to the pulse controller 4.

The deviation of the objective lens 1A with respect to the optical system base 1K of the optical head 1 is detected by the lens position detecting means 2 from the output of the lens position sensor light receiving portion 1D, and its output e is supplied to the pulse control means 4. As the deviation of the objective lens 1A, the deviation in the radial direction of the optical disc is detected. In the pulse control means 4, the pulse generation means 3
Of the output corresponding to the first pulse and the second pulse
The output of the lens position detector 2 controls the amplitude ratio of the pulse to the pulse. The output of the pulse control means 4 is applied to the actuator drive circuit 5 via the switch 8. The tracking coil 1B is energized in one direction by the pulse corresponding to the first pulse to accelerate the objective lens 1A in the track jump direction, and the pulse corresponding to the second pulse causes the tracking coil 1B to move in the other direction. Is energized in the direction of and the objective lens 1A is decelerated.

At the end of the second pulse, the MPU
An instruction to end the track jump is given to the switch 8 from 6, and the switch 8 is switched to perform normal tracking control. In FIG. 1, the pulse generation control means 30 according to the present invention first generates the first and second pulses, and then the amplitudes of these pulses depend on the output of the lens position detection means 2. Although shown as being controlled, the pulse generation control means 30 of the present invention controls the amplitude or pulse width of the two pulses according to the output of the lens position detection means 2 when two pulses are generated. Of course, it is okay to do so.

Next, an embodiment of the optical disk device of the present invention will be described with reference to FIGS. FIG. 2 is a diagram showing an embodiment of the optical disk device of the present invention. FIG. 3 is a diagram showing signal waveforms at various parts during a track jump in the optical disk device of the present invention. In FIG. 2, those having the same functions and functions as those in FIG. 1 or 5 are designated by the same reference numerals, and the description thereof will be omitted. The optical disc used in the optical disc device shown in FIG. 2 is the same as that used in the optical disc device shown in FIGS.

In FIG. 2, the output of the 4-division photodetector 1L of the optical head 1 is input to the tracking error detection means 7, and its output g is supplied to the actuator drive circuit 5 via the switch 8. The tracking error detection means 7 includes a tracking error detection circuit 7A and a phase compensation circuit 12
It consists of and. A current controlled by a signal h is supplied from the actuator drive circuit 5 to the tracking coil 1B of the optical head 1. The pulse generation means 3 and the amplitude control circuit 17 constitute a pulse generation control means 30, and the output e of the lens position detection means 2 and the output d of the direction setting circuit 16 in the pulse generation means 3 serve as the amplitude control circuit 17. Applied to.

The output f of the amplitude control circuit 17 is output via the switch 8 to the actuator drive circuit 5 during a track jump.
Is supplied to. An instruction as to whether to perform the track jump or the normal tracking control is issued from the MPU 6 to the acceleration pulse generation circuit 14, the direction setting circuit 16, and the switch 8. FIG. 3 shows an example in which the track jump is performed toward the outer peripheral side of the optical disc. In FIG. 3, i indicates a tracking error signal detected by the tracking error detection circuit 7A, and k indicates a track jump signal having a pulse width Tj applied from the MPU 6 to the switch 8 at the time of track jump.

Further, a is a first pulse having a pulse width T1 and b
Is the second pulse of pulse width T2, c is the output of the subtractor 13,
d is the output of the direction setting circuit d, f is the output of the amplitude control circuit 17, and h is the input signal of the actuator drive circuit 5.
As shown in FIG. 3, when a track jump instruction is given, the acceleration pulse generation circuit 14 generates a first pulse a having a pulse width T1. The pulse width T1 is instructed from the MPU 6 according to the track jump distance (the number of tracks). From the falling edge of the first pulse, the deceleration pulse generation circuit 15 generates the second pulse b having the same amplitude and pulse width as the first pulse. Then, the subtractor 13 subtracts the signal b from the signal a, and the resulting signal c is applied to the direction setting circuit 16. In the direction setting circuit 16,
When the track jump is performed toward the outer peripheral side, the signal c is output as it is as the signal d, and when the track jump is performed toward the inner peripheral side, the polarity of the signal c is inverted and output as the signal d.

In FIG. 3, the track is in the on-track state immediately before the track jump is performed, but when the track jump is about to be performed toward the outer peripheral side of the optical disc, the objective lens is moved toward the inner peripheral side of the optical disc. An example is shown of being energized. In this example, in the amplitude control circuit 17, the amplitude of the portion of the input signal d corresponding to the first pulse a is increased and the pulse fp1 is output.
The amplitude of the portion corresponding to the pulse b is reduced and the negative pulse fp2 is output. Here, the sum of the amplitude of fp1 and the amplitude of fp2 is fixed at a predetermined value. The pulse fp1 is applied to the tracking coil 1B of the optical head 1.
Is energized to accelerate the objective lens 1A toward the outer peripheral side of the optical disk, and then the pulse fp2 is energized in the direction opposite to the current caused by the pulse fp1 to reduce the speed of the objective lens 1A.

As a result, at the end of the track jump, the light spot is moved to approximately the center line of the target track, and the speed of the objective lens becomes approximately zero. Therefore,
Tracking control after the track jump ends
It is stable and goes on track in an extremely short time. A lens position sensor as shown in FIG. 4 may be used as the lens position detecting means for detecting the position of the objective lens with respect to the optical head, but the lens position is detected by detecting the current of the actuator 1T. It may be configured.

[0030]

According to the optical disk device of the present invention, even if the information track is largely shaken due to the eccentricity of the optical disk, the track jump is extremely stable, the seek time is shortened, and the seek error is less likely to occur. There is.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of an optical disk device of the present invention.

FIG. 2 is a diagram showing an embodiment of an optical disk device of the present invention.

FIG. 3 is a diagram showing signal waveforms at various parts during a track jump in the optical disk device of the present invention.

FIG. 4 is a diagram showing a configuration example of an optical head according to the present invention.

FIG. 5 is a block diagram showing a main part of a conventional optical disc device.

FIG. 6 is a diagram showing signal waveforms at various parts during a track jump in a conventional optical disc device.

FIG. 7 is a diagram showing a configuration example of an optical head in a conventional optical disc device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical head 2 Lens position detection means 3 Pulse generation means 4 Pulse control means 5 Actuator drive circuit 6 Microprocessor (MPU) 7 Tracking error detection means 1A Objective lens 1B Tracking coil 1C Permanent magnet 1D Lens position sensor light receiving part 1G Moving part Supporting suspension 1L 4-division photodetector 1T Tracking actuator 30 Pulse generation control circuit

Claims (1)

[Claims] 1. A tracking actuator for moving an objective lens in a radial direction of an optical disc in an optical disc apparatus for recording or reproducing an optical disc having a circular information track, and a lens for detecting a position of the objective lens. A position detecting means, a first pulse and a second pulse following the first pulse are generated, and the pulse width or amplitude of the first pulse or the second pulse is controlled according to the output of the lens position detecting means, and then output. Pulse generation control means for
An actuator drive circuit for driving the tracking actuator, wherein the actuator drive circuit is controlled according to two outputs of the pulse generation control means when performing a track jump.