JPH1196565A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk device capable of performing the track pulling-in at the time of positioning a beam spot at a target track constantly and at high speed. SOLUTION: This optical device is provided with an optical disk having plural tracks, an optical head 2 performing the recording and the reproducing of information with respect to the disk 1, an optical head positioning means 4 moving the optical head 2 along the radial direction of the disk 1, a tracking actuator 5 moving the objective lens 5a of the head 2 along the radial direction of the disk 1, a moving speed detecting means 14 detecting the moving speed of the beam spot attending on the movement of the head 2 or the objective lens 5a and a track counter means 15 counting the number of remaining tracks till the target track at the time of a seek and moreover the device is provided with a accelerating and decelerating means 18 outputting an accelerating or decelerating signal 60 to the tracking actuator 5 based on the difference between the predetermined target moving speed of the beam spot and the moving speed when the number of the remaining tracks becomes a prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical disk device, and more particularly to an optical disk device having a seek control for positioning a beam spot on a target track at high speed and with high accuracy.

[0002]

2. Description of the Related Art Conventionally, there have been the following optical disk devices. FIG. 5 is a block diagram illustrating a conventional optical disk device.

[0003] Reference numeral 1 in the figure denotes an optical disk on which tracks are formed concentrically or spirally, and reference numeral 3 denotes
This is a spindle motor for rotating the optical disc 1. Reference numeral 2 denotes an optical head that irradiates the optical disk 1 with a beam spot and outputs a reproduction signal 51, and reference numeral 4 denotes an optical head positioning unit that moves the optical head 2 in the radial direction of the optical disk 1. Reference numeral 5 denotes a tracking actuator for moving the above-mentioned beam spot in the radial direction of the optical disc 1.

Reference numeral 11 denotes a tracking error signal 52 indicating the displacement of the beam spot with respect to the track.
Is a tracking error signal detecting means for detecting the tracking error signal 5 from the reproduction signal 51.
2 is a follow-up control means for generating a follow-up control signal 53 for causing the beam spot to follow the same track from 2. Sign 1
Reference numeral 3 denotes a square wave (track count pulse) having one cycle of traversing one track from the tracking error signal 52.
Reference numeral 14 denotes a relative moving speed detecting unit that measures the period of the track count pulse 54 and converts the period into a relative moving speed 55 of the beam spot with respect to the optical disc 1.

Reference numeral 15 denotes a countdown performed from the target number of tracks to be traversed at the time of the rising of the track count pulse 54 to the output of the number of remaining tracks 56 and the target attainment when the number of remaining tracks becomes zero. It is a track counting means for generating the signal 57. Code 16
Calculates the distance to the target track from the number of remaining tracks 56 and the track pitch (track interval) at the time of seek, and calculates the target moving speed 5 of the beam spot according to this distance.
Reference numeral 17 denotes an error signal generating unit that calculates a speed difference between the target moving speed 58 and the moving speed 55. Reference numeral 20 denotes fine control switching means for selecting either the signal for keeping the tracking actuator 5 stopped or the tracking control signal 53 and transmitting the signal to the tracking actuator. Reference numeral 19 denotes coarse control switching means for selecting either the follow-up control signal 53 of the follow-up control means 12 or the speed error signal 59 of the speed error signal detecting means 17 and transmitting the selected signal to the optical head positioning means 4.

In Japanese Patent Application Laid-Open No. 62-231430, a speed detecting means 14 differentiates a tracking error signal to detect a relative moving speed of a beam spot with respect to an optical disk. A device used in combination with a period measurement type speed detecting means is disclosed.

Next, the operation of the conventional optical disk device will be described. The optical disk device according to the conventional example includes a reproduction signal 51 of a beam spot applied to the rotating optical disk 1.
, A tracking error signal 52 is generated. Then, from the tracking error signal 52, a tracking control signal 53 for causing the beam spot to follow a predetermined track.
Is generated. The follow-up control signal 53 is transmitted to the tracking actuator 5 and the optical head positioning means 4 via the fine control switching means 20 and the coarse control switching means 19, and the information is recorded and reproduced. This is a case where the recording and reproduction of information is continuously performed by causing the beam spot to follow a specific track.

Next, a case where a seek (track jump) command is issued to the optical disk device during reproduction of information will be described. First, in response to a seek command, the fine control switching means 20
Switches its output from the tracking control signal 53 of the tracking control means 12 to a stop signal for keeping the tracking actuator 5 stopped. Thus, the tracking actuator stops operating. Further, coarse control switching means 1
9 switches the output from the tracking control signal 53 to the speed error signal 59. The track count means 15 is set with the number of tracks from the current track to the target track as an initial value, and starts seeking.

During the seek, the track counting means 15 reduces the number of tracks by one at every rise of the track count pulse 54, and the target speed command means 16 calculates a target moving speed 58 from the number of remaining tracks 56, and calculates this as an error. The signal is transmitted to the signal generating means. The speed detecting means 14 calculates the beam spot moving speed 55 from the cycle of the track count pulse 54 and the track pitch. The error signal generating means 17 calculates the actual moving speed 55 from the target moving speed 58.
The speed error signal 59 is generated by subtracting. The fine control switching means 20 outputs a signal for keeping the tracking actuator 5 in a stopped state at all times.

When the optical head 2 reaches the target track, the number of remaining tracks becomes zero. For this reason, the track counting means 15 generates the target arrival signal 57. In accordance with the target reaching signal, the fine control switching means 20 and the coarse control switching means 19 switch the output to the follow-up control signal 53 and transmit the output to the tracking actuator 5 and the optical head positioning means 4. Thus, the optical head 2 is pulled into the target track, and the seek is completed.

[0011]

Problems to be solved by the invention, however, are as follows. The above conventional example has the following disadvantages. That is, in the conventional optical disk device, the tracking actuator remains stopped until the beam spot reaches the target track. For this reason, the beam spot moves to the target track by the optical head positioning means.
However, the optical head positioning means has a variation in tracking performance and a limit in accuracy in relative speed control for each track pitch during a track jump due to aging of natural friction, mechanical characteristics, and the like. For this reason, in the speed control by the optical head positioning means, the accuracy of following the target moving speed is poor,
In particular, the speed residual that can not be ignored at low speeds is
The drawback is that draw-in failure to the target track and delay of pull-in time occur.

If the relative speed of the optical head in the vicinity of the target track is significantly higher than the target speed, the moving speed of the beam spot on the target track is not reduced to a speed suitable for pulling in the track. Then, a long pull-in time occurs due to overshoot (p7), a pull-in failure (p6 portion) or an overshoot due to waiting for deceleration (p6 + p7) occurs, and the beam spot deviates from the target track. As shown in b), there is a problem that the positioning accuracy and the access time are deteriorated.

Conversely, when the moving speed near the target track is significantly lower than the target moving speed, FIG.
As shown in (c), the arrival time to the target track is longer than usual (p0 << p5), and the access time is deteriorated.

Further, in the optical disc apparatus, the relative movement speed of the beam spot with respect to the optical disc is detected by detecting the zero-cross period of the track count pulse using the output of the track count pulse generating means. For this reason, a detection lag occurs due to the period, and the detection accuracy at low speed is reduced, so that the speed control is deteriorated.

[0015]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical disk apparatus which can solve the above-mentioned disadvantages of the prior art and, in particular, can stably and quickly perform track pull-in when positioning a beam spot on a target track. With that purpose.

[0016]

According to the first aspect of the present invention, an optical disk having a plurality of tracks, an optical head for recording and reproducing information on the optical disk, and moving the optical head along a radial direction of the optical disk. Optical head positioning means, a tracking actuator for moving the objective lens of the optical head along the radial direction of the optical disk, a moving speed detecting means for detecting the moving speed of the beam spot accompanying the movement of the optical head or the objective lens, Track counting means for counting the number of remaining tracks up to the target track at the time, and a tracking actuator based on a difference between a target movement speed of the beam spot and a movement speed calculated in advance when the number of remaining tracks reaches a predetermined value. An acceleration / deceleration means for outputting an acceleration / deceleration signal to the It has adopted a formation.

With the above configuration, the number of remaining tracks to the target track is reduced, and when the beam spot approaches the target track, a speed error with respect to the target moving speed is calculated. By transmitting an acceleration / deceleration signal to the tracking actuator so as to correct this speed error, the beam spot can be quickly and accurately drawn into the target track.

According to the present invention, the target moving speed is determined according to the number of remaining tracks.
Other configurations are the same as those of the first aspect.

According to the third aspect of the present invention, the acceleration / deceleration means includes:
An acceleration / deceleration signal is output when the absolute value of the difference between the moving speed of the beam spot and the target moving speed is greater than a predetermined reference value.
This is the same as the described invention.

According to the fourth aspect of the present invention, the acceleration / deceleration means includes:
An acceleration / deceleration signal is output when the number of remaining tracks becomes one, and the other configuration is the same as that of the first or second aspect.

According to a fifth aspect of the present invention, the acceleration / deceleration means includes:
An acceleration / deceleration signal is output when the number of remaining tracks becomes half a track.
This is the same as the invention described in 2 or 3.

According to a sixth aspect of the present invention, the moving speed detecting means detects the moving speed of the beam spot based on the zero-cross period of the tracking error signal during the seek. 2,3,4
Or, it is the same as the invention described in 5.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an optical disk device of the present embodiment. Note that components similar to those of the conventional example are denoted by the same reference numerals and described.

Reference numeral 1 denotes an optical disk on which concentric or spiral tracks are formed, and reference numeral 2 denotes an optical head that irradiates the optical disk 1 with a beam spot and outputs a reproduction signal 51. Reference numeral 3 denotes a spindle motor for rotating the optical disk 1, and reference numeral 4 denotes an optical head 2.
Is an optical head positioning means for moving the optical disk 1 in the radial direction of the optical disk 1. Reference numeral 5 denotes a tracking actuator that moves the beam spot in the radial direction of the optical disc 1 through the movement of the objective lens 5a.

Reference numeral 11 denotes tracking error signal detecting means. This tracking error signal detecting means 11
Generates a tracking error signal 52 indicating the amount of displacement of the beam spot with respect to the track from the reproduction signal 51. Reference numeral 12 denotes a tracking control means for generating a tracking control signal 53 for causing the beam spot to follow a predetermined track from the tracking error signal 52.

Reference numeral 13 denotes a tracking error signal 52
Is a track count pulse generating means for generating a square wave (track count pulse) having one cycle of traversing one track. Reference numeral 14 denotes a speed detecting unit that measures the period of the track count pulse 54 and converts the period into a relative moving speed 55 of the beam spot with respect to the optical disc 1.

Reference numeral 15 denotes track counting means. The track counting means 15 counts down from the target track number to be traversed each time the track count pulse 54 rises, outputs information on the number of remaining tracks 56, and outputs a target arrival signal when the number of remaining tracks becomes zero. 57 is generated and output.

Reference numeral 16 denotes speed command means for calculating the distance to the target track based on the number of remaining tracks 56 and the value of the track pitch (known), and presenting the target moving speed 58 of the beam spot. Reference numeral 17 denotes an error signal generating means for calculating a speed error signal 59 between the target moving speed 58 and the actual moving speed 55. Reference numeral 19 denotes coarse control switching means for selecting the following control signal 53 or the speed error signal 59.

Further, the optical disk device of the present invention is equipped with the following. That is, the code 18 determines the speed error signal 59 when the number of remaining tracks is 1, and
This is an acceleration / deceleration means for calculating an acceleration / deceleration signal 60 for accelerating / decelerating the tracking actuator 5 to the target relative speed 58. Reference numeral 20 denotes a fine control switching means for selecting one of the following control signal 53 and the acceleration / deceleration signal 60.

Next, the operation of the optical disk device according to this embodiment will be described.

The optical disk device of the present embodiment has a reproduction signal 51 of a beam spot irradiated on the rotating optical disk 1.
, A tracking error signal 52 is generated. Then, a tracking control signal 53 for causing the beam spot to follow a specific track is generated from the tracking error signal 52. The tracking control signal 53 is transmitted to the tracking actuator 5 and the optical head positioning means 4 to reproduce information.

When a seek command is issued during information reproduction,
The output of the fine control switching means 20 is switched from the follow-up control signal 53 to the acceleration / deceleration signal 60. Further, the output of the coarse control switching means 19 is based on the speed error signal 59
Is switched to. In the track counting means 15, the number of tracks from the current track to the target track is set as an initial value. Thereafter, a seek is started.

During the seek, the track counting means 15 reduces the number of tracks by one each time the track count pulse 54 rises, and counts the remaining tracks.
The target speed specifying means 16 presents a target moving speed 58 based on the number of remaining tracks 56. The speed detecting means 14 calculates the relative speed 55 of the beam spot from the period of the track count pulse 54 and the track pitch. The error signal generating means 17 generates a speed error signal 59 obtained by subtracting the relative speed 55 from the target relative speed 58, and the acceleration / deceleration means 18 outputs a signal for keeping the tracking actuator 5 stopped.

Here, the acceleration / deceleration means 18 compares the speed error signal 59 with a predetermined reference value when the number of remaining tracks 56 to the target track becomes 1. When the absolute value of the speed error signal 59 is equal to or smaller than the reference value, the state is maintained. On the other hand, when the absolute value of the speed error signal 59 is larger than the reference value, the acceleration / deceleration signal 60 having a length proportional to the speed error signal 59 is output, and the speed error signal 59 is held at zero.

When the beam spot reaches the target track, the number of remaining tracks 56 becomes zero, and the target arrival signal 57 is generated by the track counting means 15. In accordance with the target arrival signal 57, the output of the fine control switching means 20 and the output of the coarse control switching means 19 are switched to the follow-up control signal 53, and the track is pulled in and the seek is completed.

As described above, the optical disk device of the present invention can precisely control the moving speed of the beam spot near the target track by providing the conventional acceleration / deceleration means 18. That is, the speed is controlled to a speed at which the beam spot can be stably and reliably drawn into the target track. Therefore, by switching from speed control to follow-up control in accordance with the target arrival signal, the beam spot is accurately positioned on the target track.

With the above configuration, even if the speed control of the optical head positioning means 4 alone does not allow sufficient deceleration at the target track and the track pull-in fails, an error in the speed error one track before the end of the seek is achieved. When the speed error exceeds the reference value at the same time, the speed error is corrected by the tracking actuator, and the track pull-in on the target track can be performed stably and reliably.

An example of the present invention which more specifically expresses the above embodiment will be described below.

In this embodiment, the optical head 2 converts reflected light from the optical disk 1 into an electric signal and outputs a PD (Photo Detect) signal 61, and a thread 7 for moving the optical head 2 in the radial direction of the optical disk 1. have. Also,
The optical disc device includes a tracking error signal detection circuit 41 that generates a tracking error signal 52 from a PD signal 61, and a phase compensation circuit 43 that outputs a tracking actuator follow-up signal 62 and a thread follow-up signal 63 that have been phase compensated for the tracking error signal 52. It has.

The optical disk device has a zero cross comparator 43. The zero-cross comparator 43 binarizes the tracking error signal 52 at the zero-cross, thereby generating a count pulse 54 whose rising edge is at the track center and whose falling edge is between tracks. The current speed calculator 31 provided in the optical disk device calculates the relative moving speed of the beam spot with respect to the optical disk from the period of the track count pulse 54 and the track pitch.

The optical disk device has a track counter 3
4 are provided. This track counter 34 is calculated from the number of tracks to be traversed when the seek command is issued.
The number of remaining tracks is detected by subtracting 1 each time the count pulse rises. Further, the optical disc apparatus includes a target speed command unit 32 for calculating a distance from the number of remaining tracks and the track pitch to a target track and specifying an appropriate target moving speed for the distance, and a target moving speed based on the target moving speed. A speed error calculation unit 33 that calculates speed error data 64 with reduced speed is provided.

The optical disk device has an acceleration / deceleration time calculation unit 35 which is a feature of the present invention. The acceleration / deceleration time calculation section 35 calculates a speed error when the target track at the time of seeking is one track remaining. And
If the absolute value of the speed error exceeds the reference value, an acceleration / deceleration time proportional to the speed error is calculated. Based on the acceleration / deceleration time, an acceleration / deceleration signal 60 in the acceleration or deceleration direction that brings the moving speed of the beam spot closer to the target relative speed is generated.

The above-described various calculation processes performed by the current speed calculation unit 31, the track counter 34, the target speed command unit 32, the speed error calculation unit 33, and the acceleration / deceleration time calculation unit 35 are actually performed by the CPU 30. The program is processed. Then, the speed error data 6 generated by the CPU 30
4 is converted to an analog thread speed control signal 65 by a DAC (digital / analog converter) 46. Then, one of the thread following signal 63 from the phase compensation circuit 43 and the thread speed control signal 65 is
It has an analog switch 44 that feeds back to the tracking actuator 5 in accordance with a switching command 66 of U30.
At the same time, an analog switch 45 is provided to feed back either the tracking actuator follow-up signal 62 or the acceleration / deceleration signal 60 to the thread 7 in accordance with the switching instruction 66 of the CPU 30.

As described above, in the present embodiment shown in FIG. 2, most of them are realized by the program processing of the CPU. FIG. 3 is a flowchart illustrating the operation.

First, when a seek command to a target track is issued, the CPU executes a seek routine shown in FIG. First, the seek direction of the thread toward the target track is set (step S1), and the number of crossing tracks (D) from the first track to the target track is set in the track counter 34 (step S2). And
The target speed (Vm) is set by the target speed command section 32 (step S2), and the target speed (Vm) is set to the speed error (Ve).
m) is substituted (step S3).

Next, the tracking actuator 5 and the servo (not shown) for the sled are released, and the control is switched to sled speed control (step S4). At the same time, the speed detection counter (count clock cycle: Tc) of the current speed calculation unit 31 is reset (Ns = 0) and then started (step S5), and the window timer is operated to prevent the rising edge count of the first track (step S5). Step S6, Step S7).

The current speed calculator 31 waits for a rising edge of the track count pulse (step S8). When the rise of the track count pulse is detected, the count value (Ns) of the speed detection counter is latched, and the known track pitch (Lt) and count value (Nt) are latched.
s), the relative velocity of the current beam spot (Vt = L
t / (Ns × Tc)) is calculated (step S10), and the speed detection counter is reset again (Ns = 0) and then started (step S11).

Next, the track counter 34 subtracts 1 from the counter (step S12), and the target speed command section 32
Is the distance (Ln = Dn) to the target track by the product of the value (D) of the track counter 34 and the track pitch (Lt).
× Lt) is calculated, and a target speed (Vm) suitable for predetermined speed control is specified (step S13).

Further, the speed error calculating section 33 calculates a speed error (Ve = Vm-Vt) by subtracting the current relative speed (Vt) from the target relative speed (Vm) (step S1).
4). If the value of the track counter 34 is not D = 1, the rise of the track count pulse is detected again, and the above control is repeated. On the other hand, if D = 1, the acceleration / deceleration time calculator 35 compares the absolute value of the speed error (Ve) with the speed error reference value (Vk) (step S16).

If the absolute value of the speed error (Ve) is larger than the speed error reference value (Vk), the acceleration / deceleration time (T = K) is calculated by integrating the absolute value (Ve) of the speed error and a constant (K). ×
Ve) is calculated (step S17). Further, when the sign of the velocity error (Ve) is positive, the same acceleration direction (FWD) as the seek direction is set (step S24), and when the sign of the velocity error (Ve) is negative, the deceleration is opposite to the seek direction. The direction (REV) is set (step S19).

Next, the acceleration / deceleration time calculation unit 35 determines that Ve = 0.
An acceleration / deceleration signal for accelerating / decelerating the beam spot in a predetermined direction by an acceleration / deceleration time (T) is output. Finally, the control waits for the rising edge of the track count pulse (step S22). When the rising of the track count pulse is detected, the servo for the tracking actuator 5 and the thread 7 is operated (step S2).
3) The track is pulled in and the seek is completed.

FIG. 4 is a waveform diagram for explaining the operation from the remaining one track in the embodiment described above. FIG.
As shown in (a), when the difference between the moving speed (Vt1 = Lt / p1) of the beam spot in the remaining one track and the target moving speed is equal to or less than the reference value, the rush speed to the target track (Vt0 = Lt / p0). ) Is also properly controlled,
Acceleration / deceleration of the tracking actuator is not required, and the track pull-in can be completed in a short time (pe).

As shown in FIG. 4B, the relative speed of the beam spot in the remaining one track (Vt2 = Lt /
p2> Vt0) and the target relative speed, when the absolute value is larger than the reference value, and at the same time, when the actual moving speed is larger than the target moving speed, the deceleration signal (T
1) is applied to the tracking actuator. Therefore, the speed at which the beam spot enters the target track (V
(t8 = Lt / p8) becomes substantially equal to the relative speed (Vt0) appropriate for the track pull-in, and the track pull-in can be completed in a short time (pe).

As shown in FIG. 4C, the moving speed (Vt3 = Lt / Lt) of the beam spot in the remaining one track.
When the difference between p3 <Vt0) and the absolute value of the target moving speed is larger than the reference value and at the same time the actual moving speed is lower than the target moving speed, the acceleration signal (T2) in the seek direction is applied to the tracking actuator. Therefore, the speed at which the beam spot enters the target track (Vt9 = Lt /
p9) is the relative speed (Vt0) appropriate for pulling in the truck
And the transit time (p
9) is reduced to near the standard time (p0), and the track pull-in can be completed in a short time (pe).

Therefore, in the seek operation of the optical disk apparatus of the present invention, the speed control of the beam spot is performed with the moving speed output from the target speed commanding means 16 as a target, and the tracking actuator 5 operates according to the speed error in the remaining one track. Since the speed control of the beam spot is performed, the speed at which the beam spot enters the target track is appropriately controlled, and the track can be stably and reliably drawn into the target track.

The case where the acceleration / deceleration control is performed one track before in the seek operation has been described above. However, similarly, the same object can be achieved by the speed control for each half track and the speed correction control before the remaining half track. Further, it is also possible to perform the above-described control on the target track two or several tracks before the target track.

[0057]

The present invention is configured as described above.
According to the first aspect of the present invention, when the number of remaining tracks reaches a predetermined value, an acceleration / deceleration signal is output to the tracking actuator based on a difference between a target movement speed of the beam spot and a movement speed calculated in advance. With means.
Therefore, not only the optical head positioning means but also the beam spot moving speed of the beam spot is controlled by the tracking actuator when the beam spot approaches the target track, so that accurate tracking control can be performed in a short time. Effect.

In the second aspect of the present invention, the target moving speed is determined according to the number of remaining tracks. For this reason, it is possible to calculate the optimum target moving speed corresponding to the number of remaining tracks, and not only to control the moving speed of the beam spot near the target track, but also to perform the optimum speed control throughout the seek. Can be achieved.

According to the third aspect of the present invention, the acceleration / deceleration means includes:
When the absolute value of the difference between the moving speed of the beam spot and the target moving speed is larger than a predetermined reference value, an acceleration / deceleration signal is output. Therefore, when the speed error is large, the tracking actuator positively corrects the speed, which brings about an excellent effect that the relative speed of the beam spot can approach the target relative speed in a short time.

According to a fourth or fifth aspect of the present invention, the acceleration / deceleration means performs acceleration / deceleration control of the beam spot one track pitch or half a track pitch before the seek target track. Therefore, when positioning the beam spot on the target track, the acceleration / deceleration control is performed immediately before, and an excellent effect that the beam spot can be accurately drawn in a short time is produced.

According to a sixth aspect of the present invention, the moving speed of the beam spot is detected based on the zero-cross period of the tracking error signal during the seek.
Therefore, there is an excellent effect that the moving speed can be accurately detected without using a sensor or the like for specifically detecting the moving speed of the beam spot, and the information on the moving speed can be used for tracking control.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a specific embodiment of the optical disk device disclosed in FIG.

FIG. 3 is a control flowchart of the optical disk device disclosed in FIG. 2;

FIG. 4 is a waveform chart for explaining the operation of the optical disk device disclosed in FIG. 1 in the vicinity of a target track, and FIG. 4 (a) shows a case where a moving speed of a beam spot is appropriate;
4B shows a case where the moving speed is too fast, and FIG. 4C shows a case where the moving speed is slow.

FIG. 5 is a block diagram showing a conventional optical disk device.

6A and 6B are waveform diagrams for explaining the operation of the optical disk device disclosed in FIG. 5 near a target track, and FIG. 6A shows a case where the moving speed of a beam spot is appropriate;
6B shows a case where the moving speed is too fast, and FIG. 6C shows a case where the moving speed is slow.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 2 Optical head 3 Spindle motor 4 Optical head positioning means 5 Tracking actuator 14 Moving speed detecting means 15 Track counting means 18 Acceleration / deceleration means 55 Moving speed 56 Number of remaining tracks 58 Target moving speed 60 Acceleration / deceleration signal

Claims (6)

[Claims] 1. An optical disk having a plurality of tracks,
An optical head for recording and reproducing information on the optical disc;
Optical head positioning means for moving the optical head along the radial direction of the optical disc; tracking actuator for moving the objective lens of the optical head along the radial direction of the optical disc; and moving the optical head or the objective lens. Moving speed detecting means for detecting the moving speed of the beam spot, and track counting means for counting the number of remaining tracks up to the target track at the time of seeking, and is calculated in advance when the number of remaining tracks reaches a predetermined value. An optical disc device comprising: an acceleration / deceleration unit that outputs an acceleration / deceleration signal to the tracking actuator based on a difference between a target movement speed of the beam spot and the movement speed. 2. The optical disk device according to claim 1, wherein the target moving speed is determined according to the number of remaining tracks. 3. An acceleration / deceleration signal is output when an absolute value of a difference between a moving speed of the beam spot and a target moving speed is larger than a predetermined reference value. 3. The optical disk device according to 1 or 2. 4. The optical disk apparatus according to claim 1, wherein said acceleration / deceleration means outputs said acceleration / deceleration signal when said remaining track number becomes one track. 5. The optical disk device according to claim 1, wherein said acceleration / deceleration means outputs said acceleration / deceleration signal when said number of remaining tracks becomes half a track. 6. The moving speed detecting device according to claim 1, wherein said moving speed detecting means detects a moving speed of a beam spot based on a zero cross period of a tracking error signal during a seek. Optical disk device.