JP2000173069A - Track jump control method of optical disk device and track jump control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably perform track jump operation even if a disk is eccentric by detecting the traveling direction of the eccentricity of a disk immediately before track jump and controlling at least one pulse height value of acceleration and deceleration pulse for moving an optical beam in the radius direction of a disk according to the detection result. SOLUTION: A track jump device 1 generates a jump operation control signal when a jump operation instruction is received from a CPU and a switch 4 is turned off so that the output of a servo circuit compensation circuit HPF 31 cannot be inputted to a light beam drive means 9. Further, a value that is obtained by holding the output of an LPF 32 with a hold means 5 and acceleration and deceleration pulse outputted from a jump circuit generation circuit 8 are added and are inputted to a light beam drive means for performing track jump operation. The jump pulse generation means 8 controls pulse height values of the acceleration and deceleration pulse according to the output of an eccentricity direction detection means 7 of a disk.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a track jump control method and a track jump control device for an optical disk device.

[0002]

2. Description of the Related Art In an optical disk apparatus, it is necessary to move a light beam by a predetermined number of tracks in a radial direction of the disk in order to access an optical beam at an arbitrary position on the disk. Hereinafter, a basic operation when such a so-called track jump operation is performed will be described.

[0003] DSP (Digital Signal)
The processor is a CPU (Central Processing) that controls the entire optical disc apparatus.
When a track jump command is received from the unit, a driving signal for moving the optical beam in the radial direction of the disk, that is, a driving signal for driving a track jump actuator is transmitted, and the light beam is used as a target second track. Move the pickup to move toward.

At this time, since the actual disk has an eccentricity, even when the optical beam is moved by the same number of tracks in the radial direction of the disk, a necessary drive depends on a place before the start of the track jump of the optical beam. Power is different.

Therefore, if only a single drive signal is used as a signal for driving the track jump actuator even if the amount of movement is the same, a track jump cannot be performed to a desired place. .

In order to perform a high-speed and accurate track jump, an acceleration pulse is applied from a current track to a substantially intermediate position of a target track, and a deceleration pulse is applied to a target track after passing the intermediate position. I have to.

However, the determination of the deceleration pulse requires two parameters, the speed at which the light beam moves on the disk surface and the current position. If these two parameters are not known, an optimal deceleration pulse can be obtained. Therefore, a stable track jump cannot be performed.

Therefore, for example, in Japanese Patent Application Laid-Open No. 9-120549, a low frequency component of a drive signal in the disk radial direction of a light beam immediately before a track jump operation is held, and the acceleration pulse for the jump operation is added to the signal. Alternatively, there is disclosed a track jump control technique in which a track jump operation is performed by adding a deceleration pulse to reduce the influence of eccentricity of a disk.

[0009]

Generally, when the disk is eccentric, the low frequency component of the drive signal of the optical beam in the radial direction of the disk changes with time.
It is shown as follows. The horizontal axis represents time, and the vertical axis represents the amplitude of the drive signal of the optical beam in the radial direction of the disk.

In FIG. 1, the track number immediately before the track jump operation is m, and the drive signal waveform at that time is indicated by a solid line. Similarly, the track number after the end of the track jump operation is denoted by n (m ≠ n), and the drive signal waveform at that time is indicated by a chain line.

Here, it is assumed that the track jump operation is started from two points on the track m currently being scanned and having the same amplitude value of the drive signal, that is, points a and b in FIG. In this case, the points on the track n after a lapse of a certain time from the points a and b, the points a ′ and b ′ are the light beam positions after the track jump operation.

In the conventional track jump apparatus, the hold value of the drive signal of the optical beam in the radial direction of the disk immediately before the track jump operation is indicated by a dotted line in both cases at points a and b. As described above, the drive signal applied to the drive unit during the track jump operation is the same because the value c is the same.

However, the driving force required for the track jump is a value proportional to the difference A between the amplitude value at the point a 'and the amplitude value at the point a when, for example, the track jump operation is started from the point a. When the track jump operation is started from the point b, the value is proportional to the difference between the amplitude value at the point b 'and the amplitude value B at the point b.

That is, when the track jump operation is performed from the point b, the driving force to be further applied is substantially zero because B ≒ 0, whereas when the track jump operation is performed from the point a, the driving force is increased. The force is A · k (where k is a coefficient).

As is apparent from the drawing, in the case where the jump operation is performed from the point a and the case where the jump operation is performed from the point b, it is difficult to stably perform the track jump control using only a single jump drive signal. Can not.

[0016]

Therefore, detecting means for detecting the direction of eccentric movement of the disk immediately before performing a track jump is provided, and at least one of an acceleration pulse and a deceleration pulse of a jump is provided in accordance with the direction of eccentric movement. It is characterized in that a track jump operation is stably performed by controlling a high value or a pulse width.

According to the track jump control method for an optical disk device of the present invention, an acceleration pulse and a deceleration pulse are applied to a driving means for moving an optical beam position of the optical disk device in a radial direction of the disk for a certain period of time. Furthermore, of the signals used to move the light beam in the radial direction of the disk, a signal that has a gain improved in the low frequency range included in the servo error signal and that holds the value immediately before the track jump operation is added. In this method, the moving direction of the eccentricity of the disk immediately before the track jump is detected, and the peak value of at least one of the acceleration pulse and the deceleration pulse is controlled according to the detection result.

According to the track jump control method of the optical disk device of the present invention, similarly, the moving direction of the eccentricity of the disk immediately before the track jump is detected, and at least one of the acceleration pulse and the deceleration pulse according to the detection result. The application time is controlled.

According to a third aspect of the present invention, in the track jump control method according to the first or second aspect, the detection of the moving direction of the eccentricity of the disk includes the step of: Of the signals used to move in the direction, based on the signal whose gain in the low frequency range included in the servo error signal has been improved,
It is characterized by comparing the value of the low-frequency component immediately before the track jump with the value of the low-frequency component before a predetermined time.

According to a fourth aspect of the present invention, in the track jump control method according to the first or second aspect, the detection of the moving direction of the eccentricity of the disk includes the step of: The signal used for moving in the direction, the signal obtained by removing the high-frequency component from the signal in which the gain in the low-frequency range included in the servo error signal is improved, and the value immediately before the track jump and the fixed time It is characterized in that it is performed by comparing previous values.

According to the track jump control device for an optical disk device of the present invention, an acceleration pulse and a deceleration pulse are applied to the drive means for moving the optical beam position of the optical disk device in the radial direction of the disk for a certain period of time. Furthermore, of the signals used to move the light beam in the radial direction of the disk, a signal that has a gain improved in the low frequency range included in the servo error signal and that holds the value immediately before the track jump operation is added. A track jump control device, comprising: detecting means for detecting a moving direction of eccentricity of a disk immediately before a track jump; and jump pulse generating means for changing and outputting a jump pulse value according to the detection result. I have.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> A first embodiment of a track jump control method for an optical disc device as an example of the present invention will be described with reference to the drawings. The description will be made in the order of basic configuration tracking and track jump control method jump pulse control method.

FIG. 1 is a circuit diagram of a track jump device 1 in an optical disk device according to the present embodiment. Error signal generator 2
, A servo error signal is generated from a signal from an optical head (not shown). The servo phase compensation circuit 3 generally has an HPF (Hi) for advancing the phase in a high frequency range.
gh Pass Filter) 31 and LPF (Low Pass Filter) to increase the gain in the low frequency range
32.

The output of the HPF 31 is connected to one end of the switch 4, and the other end of the switch 4 is connected to the light beam driving means 9 via an adder. The open and short-circuit states of the switch 4 are controlled by an external jump operation control signal. The jump operation control signal is, for example, at a high level in the case of a tracking operation and at a low level in the case of a track jump operation, and the switch 4 is short-circuited and open at each level.

The output of the LPF 32 is supplied to the holding means 5, LP
F6 and the eccentric direction detecting means 7 respectively.
The holding means 5 receives an LPF signal by a jump operation control signal.
Through (pass) or hold (hold) the 32 outputs
Then, for example, the jump operation control signal enters a through / hold state according to the high level / low level.

The average value of the low-frequency components in the signal obtained by amplifying the servo error signal by the LPF 6 is calculated.
In FIG. 1, the cutoff frequency of the LPF 6 is selected as a value for removing a noise component and an eccentric frequency of the disk included in the servo error signal. The output of the LPF 6 is a value excluding noise and the like, and is an average driving voltage applied to the optical head driving unit 10. The optical head driving means 10 includes a DC motor, a rotation-linear motion conversion mechanism, and the like.

The reason why the LPF 6 is set to a value for removing the eccentric frequency of the disk will be described below. As a driving source of the optical head driving means 10, a linear motor or a DC motor is generally used. When a linear motor is used, it has an advantage that it can sufficiently follow the disk eccentric frequency because of its excellent high-speed response. However, there is a disadvantage that the cost is high because the mechanism is precise. On the other hand, when a DC motor is used, it can be configured at a low cost, but requires a conversion mechanism such as a screw that converts rotary motion into linear motion. The disadvantage is that it cannot follow high frequencies.
Which to choose is determined comprehensively from the performance of the optical disk device such as cost and high-speed response,
In a relatively low-priced optical disk device such as a CD or a CD-ROM, it is required to reduce the cost of the device and parts.

Therefore, when a DC motor is used as the drive source as in the present embodiment, the optical head cannot follow the eccentric frequency, so that the eccentric frequency of the disk is removed as the frequency characteristic of the LPF 6. Designed to. In terms of circuit characteristics, the gain at the eccentric frequency of the signal input to the optical head driving means 10 is extremely smaller than the gain at the eccentric frequency of the signal input to the light beam driving means 9. In this case, the eccentricity is controlled only by the control of the light beam driving means 9.

When a linear motor is used as the drive source of the optical head drive means 10, it can follow the eccentric frequency sufficiently. Therefore, the frequency characteristic of the LPF 6 is designed to include the eccentric frequency of the disk. I do.
In terms of circuit characteristics, the gain at the eccentric frequency of the signal input to the optical head driving means 10 is equal to or slightly lower than the gain at the eccentric frequency of the signal input to the light beam driving means 9. In this case, the eccentricity is controlled by the control of the optical head driving means 10 in addition to the control of the light beam driving means 9.

The eccentric direction detecting means 7 detects the eccentric direction of the disk from the output signal of the LPF 32, and outputs the result to the jump pulse generating means 8. Hereinafter, a method of detecting the eccentric movement direction will be described. As one of the detection methods, an eccentric frequency component is extracted from the track servo error signal, and the eccentric movement direction can be detected by differentiating the signal.

However, in recent years, servo signals are often processed digitally using a DSP or the like.
In such a case, the differentiating circuit is not necessary, and the output value of the low frequency component of the track servo signal processing circuit is stored in the memory, and the value before a certain time (T1) is compared with the current value, so that the eccentricity is obtained. The moving direction can be detected. here,
The above T1 is a time which is shorter than a fraction of the rotation cycle of the disk.

For example, a case where the low-frequency component of the track servo signal processing circuit has a waveform as shown in FIG. Here, the time T2 represents a processing cycle of the low frequency component of the track servo signal processing circuit. In this example, since the time T1 is four times the time T2, it is necessary to store the output values for four times. Assume that the output value of the low frequency component at the start of the track jump operation is A, and the output value before time T1 is B. Assuming that the upper side of the figure represents the outer circumferential direction, the output value A is higher than the output value B, so the eccentric movement direction at the start of the track jump operation is the outer circumferential direction.

The jump pulse generating means 8 controls the peak value or pulse width of the acceleration pulse and the deceleration pulse according to the output of the eccentric movement direction detecting circuit 7 for the disk. The relationship between the input signal from the eccentric movement direction detection circuit 7 and the output signal of the jump pulse generation circuit 8 is created in advance in an LUT (lookup table).

Tracking and Track Jump Control Method Next, control methods in the tracking and track jump operations will be described. First, during the tracking operation, the switch 4 is in a short-circuit state because the jump operation control signal is at a high level. Also, the hold means 5 is in a through state, and no signal is output from the eccentric direction detecting means 7 and the jump pulse generating means 8.

After passing through the servo phase compensation circuit 3, the servo error signal is input to the optical beam driving means 9. The light beam driving means 9 is an actuator provided for changing, for example, the angle of an objective lens provided in the optical head or the position with respect to the optical axis. As a result, the light beam scanning position on the disk is corrected, and feedback control is performed so that a desired track is always scanned.

The low-frequency component of the signal passing through the LPF 32 is further extracted by the LPF 6 and input to the optical head driving means 10.

This signal is a drive signal for controlling the position of the entire optical head in the disk radial direction. When performing continuous reproduction beyond the beam movable range of the optical beam driving means, tracking control is performed by moving the entire optical head. Since such a movement is at a low speed, the movement can be sufficiently followed by the optical head driving means.

Next, when performing a track jump operation, in order to release the above-described tracking control, a jump operation control signal is issued when a jump operation command is issued from a processing circuit for controlling the entire optical disk device (not shown), for example, a CPU. Becomes low level and turns off switch 4,
The output of the HPF 31 of the servo phase compensation circuit 3 is prevented from being input to the light beam driving means 9. Furthermore, LPF3
2 is added to the value obtained by holding the output of 2 by the holding means 5 and the acceleration pulse and the deceleration pulse output from the jump pulse generation circuit 8, and the result is input to the light beam driving means 9 to perform a track jump operation.

The jump pulse generation circuit 8 controls the peak value or pulse width of the acceleration pulse and the deceleration pulse in accordance with the output of the eccentric movement direction detection circuit 7 for the disk. Also,
In some cases, a drive signal is applied to the optical head driving means 10 according to the moving distance of the track jump. That is, when the required beam movement amount cannot be obtained only by driving the light beam driving unit 9, the entire optical head is moved in the disk radial direction by driving the optical head driving unit 10.

As described above, the low frequency component is extracted from the error signal, the eccentric direction of the disk is measured from the change direction of the signal, and the light beam driving means 9 or the optical head driving means is measured based on the eccentric direction detection signal. Since the crest value or pulse width of the acceleration pulse and deceleration pulse to be added to is controlled,
An optimum driving force can be generated, and as a result, an accurate and stable track jump can be performed.

Next, an example in which the peak value of the jump pulse is controlled according to the eccentric moving direction will be described. Here, FIG. 5 is an example of a jump pulse in the case of jumping in the outer circumferential direction, and is composed of an acceleration pulse having a pulse width ta and a deceleration pulse having a pulse width tb. The pulse widths of the acceleration pulse and the deceleration pulse are constant (ta = tb).

As shown in FIG. 5 (a), a basic jump pulse is a pulse having the same peak value and the opposite polarity between the acceleration pulse and the deceleration pulse. Let the absolute value of the peak value of the basic pulse be a1.

Light beam driving means 9 at the start of jump operation
When the signal output value of the low frequency component of the drive signal is b, the jump pulse waveform when the direction of the eccentric movement is not considered, as shown in FIG. The result is a shifted waveform. However, if the direction of movement of the eccentricity at the start of the jump operation is the outer peripheral direction when jumping in the outer peripheral direction, an extra driving force in the outer peripheral direction is required more than the basic jump pulse.

Therefore, the jump pulse when the eccentric movement direction is detected as the outer peripheral direction is as shown in FIG.
By increasing the peak value of the acceleration pulse (a1 <a2), the driving force in the outer peripheral direction is increased.

When the direction of the eccentric movement is the inner circumferential direction, the driving force in the outer circumferential direction may be small, so that the peak value of the acceleration pulse is reduced as shown in FIG. 5D (a1> a3).

The values of a2 and a3 are obtained in advance by experiments or the like. In the above description, the case where the peak value of the acceleration pulse is controlled according to the moving direction of the eccentricity is described. However, it is also possible to control the peak value of the deceleration pulse, and further, the peak value of both the acceleration pulse and the deceleration pulse is controlled. It is also effective to do so.

The method of controlling the peak value of the acceleration pulse, the deceleration pulse, or both the acceleration pulse and the deceleration pulse while keeping the pulse width constant has been described, but the pulse width is controlled by keeping the pulse peak value constant. It is possible to control the driving force. In this case, when the pulse width of the reference pulse is eccentric in the outer circumferential direction or the inner circumferential direction, the pulse width is controlled to increase or decrease, respectively.

Further, as another embodiment, it is possible to use a combination of the pulse crest value control method and the pulse width control method.

<Second Embodiment> A second embodiment of the present invention will be described with reference to FIG. The description of the overlapping part will be omitted. FIG. 1 shows an example in which the direction of eccentric movement is detected from a low-frequency component of the drive signal input to the light beam driving means 9, but FIG.
This is an example of detecting an eccentric movement direction from a drive signal input to 0.

Generally, since the processing cycle of the drive signal of the optical head driving means 10 is longer than the processing cycle of the low frequency component of the drive signal of the light beam driving means 9, the drive signal of the optical head driving means 10 is eccentric. In the case of detecting the moving direction, the amount of memory for storing the output value can be reduced.
Therefore, the first embodiment has the advantages that the number of components can be reduced and the manufacturing cost of the optical disk device can be reduced.

However, since the driving signal of the optical head driving means 10 may be generated with a frequency component lower than the eccentric frequency, a filter having a characteristic of removing the eccentric frequency like the LPF 6 shown in FIG. 1 is used. If the signal after passing is used, the eccentric movement may not be sufficiently detected.

Therefore, as shown in FIG.
In particular, the cutoff frequency of the LPF 6 is selected to a value that removes a noise component included in the servo error signal but does not remove the eccentric frequency of the disk. The output of the LPF 6 is a value excluding high-frequency noise components, and is an average driving voltage applied to the optical head driving means 10.

As described above, the eccentric direction can be detected from the signal for driving the optical head driving means 10.
Whether the eccentric movement direction is detected using the drive signal of the optical head driving means 10 or the low frequency component signal among the drive signals of the light beam driving means 9 has advantages and disadvantages. The determination may be made based on the frequency characteristics of the circuit 3.

[0054]

According to the present invention, the disk eccentric direction detecting means is provided, and the jump pulse applied to the light beam driving means or both of the light beam driving means and the optical head driving means is controlled based on the result. Thus, a jump operation can be stably performed even if the disk is eccentric.

[Brief description of the drawings]

FIG. 1 is a configuration example of a track jump circuit of an optical disc device according to the present invention.

FIG. 2 is another configuration example of a track jump circuit of the optical disc device according to the present invention.

FIG. 3 is a waveform example of a low-frequency component of an optical beam drive signal.

FIG. 4 is an example of a configuration of a track jump circuit of a conventional optical disc device.

FIG. 5 is a control example of a jump pulse according to the present invention.

FIG. 6 is an example of eccentric movement direction detection according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Track jump apparatus 3 Servo phase compensation circuit 5 Hold means 6 LPF 7 Eccentric direction detection means 9 Light beam drive means 10 Optical head drive means

Claims (5)

[Claims] An acceleration pulse and a deceleration pulse are respectively applied to a drive means for moving an optical beam position of an optical disk device in a disk radial direction for a predetermined time, and further used for moving an optical beam in a disk radial direction. A signal having an improved gain in a low frequency range included in a servo error signal among signals obtained by the servo error signal, and adding a voltage holding a value immediately before a track jump operation. A track jump control method comprising: detecting a moving direction of a moving object; and controlling a peak value of at least one of an acceleration pulse and a deceleration pulse according to the detection result. 2. An accelerating pulse and a decelerating pulse are applied to a drive means for moving an optical beam position of an optical disk device in a radial direction of a disk, respectively, for a predetermined period of time, and further used for moving an optical beam in a radial direction of the disk. A signal having an improved gain in a low frequency range included in a servo error signal among signals obtained by the servo error signal, and adding a voltage holding a value immediately before a track jump operation. A track jump control method comprising: detecting a moving direction of an object; and controlling an application time of at least one of an acceleration pulse and a deceleration pulse in accordance with the detection result. 3. The method of detecting the direction of movement of the eccentricity of the disk includes detecting a signal having an improved gain in a low frequency range included in a servo error signal among signals used for moving the light beam in a radial direction of the disk. 3. The track jump control method according to claim 1, wherein the method is performed by comparing the value of the low-frequency component immediately before the track jump with the value of the low-frequency component before a predetermined time. 4. A signal used to move the optical head in the radial direction of the disk for detecting the eccentric movement direction of the disk, wherein the signal has an improved gain in a low frequency range included in the servo error signal. 3. The track jump control method according to claim 1, wherein the control is performed by comparing a value immediately before the track jump with a value before a predetermined time based on a signal from which a high frequency component is further removed. 5. An accelerating pulse and a decelerating pulse are applied to a drive means for moving an optical beam position of an optical disk apparatus in a radial direction of a disk, respectively, for a predetermined time, and further used for moving an optical beam in a radial direction of the disk. A track jump control device that adds a voltage that holds a value immediately before a track jump operation, which is a signal having an improved gain in a low frequency range included in a servo error signal among signals obtained from the servo error signal, includes: 2. A track jump control device comprising: a detecting means for detecting a moving direction of a track; and a jump pulse generating means for changing and outputting a jump pulse value according to the detection result.