JPH05258317A - Optical disk device - Google Patents

Abstract

(57) [Abstract] [Purpose] To stabilize the jumping of the optical head. [Arrangement] An acceleration signal generation circuit 12 for generating an acceleration signal applied to an actuator 5 that causes the optical head PH to jump to an adjacent track, a timer 11 for measuring an acceleration time, and a deceleration signal generation for generating a deceleration signal applied to the actuator 5. A circuit 13 and an inflection point detection circuit 9 for detecting an inflection point of the difference signal of the signals output by the photodetectors 4a and 4b are provided, and based on the detection result of detecting the inflection point of the difference signal, The deceleration force is controlled to be adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device in which an optical head is jumped to an adjacent track.

[0002]

2. Description of the Related Art A seek operation by a step jump of a conventional optical disk device of this type is, for example, February 10, 1989.
"Optical Disc Technology" issued by Radio Technology Co., Ltd. on the day
163 page 163, it shows a state in which a fine seek is performed by repeating the operation of traversing one track (track jump of one track) when the number of laser beams traversing the track to the target track is small. Then, use positive and negative pulse currents with the same amplitude and time width so that the laser beam can move to the adjacent track in the shortest time, and supply the negative pulse current to the tracking actuator following the positive pulse current. I have to.

[0003]

However, there is a variation in the sensitivity of the actuator that seeks the optical head that emits the laser beam. Therefore, the time required to jump the optical head depends on the actuator,
There is a problem that the laser beam may not be able to jump to an appropriate position in a predetermined time. Further, the amplitude of the pulse current supplied to the actuator is limited by the control system and the acceleration time of the optical head is limited. On the other hand, if the acceleration time is lengthened, external impact may affect the smooth jumping operation. There is a problem that there is

In view of such a problem, the present invention provides an optical disk device capable of jumping an optical head to an adjacent track within a predetermined time even if the sensitivities of actuators for jumping the optical head to the adjacent track are different. To aim.

[0005]

An optical disk device according to the present invention comprises means for generating an acceleration signal to be supplied to an actuator for jumping an optical head to an adjacent track in order to accelerate the optical head for projecting a light beam onto the optical disk. , Means for measuring the moving time to the middle of the distance the optical head moves to the adjacent track, means for controlling the deceleration signal supplied to the actuator to decelerate the optical head, and light after the deceleration signal is supplied. And a means for detecting an inflection point of the signal detected by the head, generating an acceleration signal for making the moving time a predetermined time to accelerate the optical head, and decelerating the optical head from the end point of the acceleration. The deceleration signal is controlled to be adjusted based on the detection result of the inflection point.

[0006]

The accelerating signal is supplied to the actuator to accelerate the optical head in the middle of the distance to the adjacent track in a predetermined time. From the end of acceleration, a deceleration signal is supplied to the actuator to decelerate the optical head. After supplying the deceleration signal,
The inflection point of the signal related to the signal detected by the optical head is detected, and the deceleration signal is controlled based on the detection result.
As a result, the deceleration signal can be controlled to be adjusted according to the acceleration signal, and the optical head can be made to jump to the adjacent track in a predetermined time.

[0007]

The present invention will be described in detail below with reference to the drawings showing the embodiments thereof. FIG. 1 is a block diagram showing the configuration of an optical disk device according to the present invention. A light beam is projected from a semiconductor laser (not shown) onto the optical disk 2 rotated by the disk motor 1, and the reflected light of the optical disk 2 passes through the objective lens 3 and enters the photodetectors 4a and 4b. It has become.

The objective lens 3 is moved in the radial direction of the optical disc 2 by an actuator 5 which is, for example, a linear motor. The objective lens 3 and the photodetectors 4a and 4b form an optical head PH. Photo detector 4a
Detection signal to the positive input terminal + of the differential amplifier 6
The detection signal of 4b is input to the negative input terminal-of the differential amplifier 6. The difference signal that is the output signal of the differential amplifier 6 is a servo circuit 7, and a zero-cross detection circuit 8 that detects a zero-cross point of the difference signal.
And the inflection point detection circuit 9 for detecting the inflection point of the difference signal.

The output signal of the servo circuit 7 is input to the adder 10. The detection signal of the zero-cross detection circuit 8 is the timer 11,
It is input to the acceleration signal generation circuit 12 and the deceleration signal generation circuit 13. Time signal measured by timer 11 and inflection point detection circuit 9
The detection signal of is input to the CPU 14. A control signal is input from the CPU 14 to the acceleration command signal generation circuit 15 and the deceleration command signal generation circuit 16, and is also input to the acceleration signal generation circuit 12 and the deceleration signal generation circuit 13.

The acceleration command signal output from the acceleration command signal generation circuit 15 and the acceleration signal output from the acceleration signal generation circuit 12 are input to the timer 11. The deceleration command signal output from the deceleration command signal generation circuit 16 is input to the deceleration signal generation circuit 13 and the inflection point detection circuit 9. The acceleration signal output from the acceleration signal generation circuit 12 and the deceleration signal output from the deceleration signal generation circuit 13 are input to the adder 10, and the output signal of the adder 10 is given to the actuator 5.

Next, the operation of jumping the optical head of the optical disk device constructed as described above will be described with reference to the flowchart of FIG. 2 showing the control contents of the CPU 14 and FIG. 3 showing the change of the difference signal corresponding to the moving state of the optical head. It will be described together with the waveform diagram. In FIG. 2, the vertical axis represents the light beam projection position, the horizontal axis represents time, and the line between A and B is the adjacent track position.

When a light beam from a semiconductor laser (not shown) is projected onto the rotating optical disk 2, the reflected light passes through the objective lens 3 and enters the photodetectors 4a and 4b. As a result, the photodetectors 4a and 4b output a signal corresponding to the light intensity of the received reflected light and input it to the differential amplifier 6. From the differential amplifier 6, a signal related to the detection signal of the optical head PH, that is, a signal of a difference between the signals of both photodetectors 4a and 4b,
An S-curve difference signal is obtained. This difference signal becomes 0 without any change when the projection position of the light beam projected on the optical disk is on the track.

Therefore, this difference signal is input to the servo circuit 7 and a drive current corresponding to the difference signal is given to the actuator 5 via the adder 10 to control the position of the optical head PH and project it on the optical disk. Tracking servo is performed to position the projected position of the light beam on the track.

By the way, when the light beam is moved from the track which is currently projecting the light beam to the adjacent track, that is, when the optical head PH is jumped, the CPU 14 outputs the acceleration command signal generation circuit 15 and the acceleration signal generation signal. Input a control signal to the circuit 12. As a result, the acceleration command signal generation circuit 15
Gives an acceleration command signal to the timer 11 and the acceleration signal generation circuit 12, and the timer 11 starts time measurement, and the acceleration signal generation circuit 12
Inputs an acceleration signal corresponding to the control signal from the CPU 14 to the adder 10 and supplies the output signal of the adder 10 to the actuator 5 to start the acceleration of the optical head PH (S1). Due to the acceleration of the optical head PH, the light beam projected on the optical disk 2 is separated from the track so far, whereby the difference signal increases in the positive direction (upward direction of the paper) and then decreases as shown in FIG. Go

When the zero-cross detection circuit 8 detects that the difference signal has reached the zero-cross point 0 shown in FIG. 3, the detection signal is input to the timer 11, the acceleration signal generation circuit 12 and the deceleration signal generation circuit 13. Then, the timer 11 stops measuring time, the acceleration signal generation circuit 12 stops outputting the acceleration signal, and the deceleration signal generation circuit 13 becomes ready to output the deceleration signal.

Therefore, the CPU 14 checks the time counting operation of the timer 11 to determine whether or not the acceleration is completed (S2). When it is determined that the acceleration is completed, the time Y _n required for the acceleration, that is, the timer 11 is determined.
CPU 14 captures the clocked time of (S3). Then, a control signal for controlling the deceleration signal is input from the CPU 14 to the deceleration signal generation circuit 13, and a control signal is input to the deceleration command signal generation circuit 16. As a result, the deceleration command signal generation circuit 16 inputs the deceleration command signal to the deceleration signal generation circuit 13, the deceleration signal generation circuit outputs the deceleration signal to the adder 10, and the output signal of the adder 10 to the actuator 5. To start decelerating the optical head PH (S
Four).

As a result, the difference signal increases in the negative direction from the zero crossing point 0 and then decreases as shown in FIG. Then, the CPU 14 checks the detection signal of the inflection point detection circuit 9 to determine whether or not the inflection points (points R ₁ , R ₂ and R ₃ in FIG. 3) of the difference signal are detected, and the deceleration is completed. Or not (S
Five). When determining that the deceleration is completed, the CPU 14 takes in the value X _{n of the} difference signal (S6), and subsequently, the value X _{n + 1} of the difference signal thereafter.
Take in (S7).

[0018] Then, the value X _n and X _{n + 1} of both the difference signal and compares (S8), if larger than the value X _n is X _{n + 1} of the difference signal, the X n _{+ 1} X _n (S9), the difference signal value X _{n + 1} is again taken in (S7), and both difference signal values X _n and X _{n + 1} are again obtained.
And are compared in magnitude (S8). If it is determined that X _n is smaller than X _{n + 1} , the value X _{n + 1} of this difference signal is set as the value of the inflection point of the difference signal (S10), that is, the deceleration end position of the optical head PH.

Next, the deceleration end position is the straight line A shown in FIG.
It is determined whether or not the above (S11). Here, as shown by the solid line in FIG. 3, when the deceleration is completed at the position R ₁ that exceeds the straight line A, it is determined that the deceleration is insufficient because the line between the straight lines A and B which is the adjacent track is exceeded. In step S12, the deceleration signal generated by the deceleration signal generation circuit 13 is incremented by +1 by the control signal from the CPU 14 to increase the deceleration force (S13). As a result, the deceleration end position is moved between the straight lines A and B.

On the other hand, if it is determined in step (S12) that the deceleration end position is less than or equal to the straight line A, then it is determined whether or not it is less than or equal to the straight line B (S14), and as shown by the alternate long and short dash line in FIG. When the deceleration is completed at the position R ₃ before the straight line B, it is judged that it is over-deceleration because it has not reached between the straight lines A and B which are the adjacent tracks (S15), and the control signal from the CPU 14 In addition, -1 is added to the deceleration signal output from the deceleration signal generation circuit 13 to weaken the deceleration force (S16). As a result, the deceleration end position is moved between the straight lines A and B.

If it is determined that the deceleration end position is greater than or equal to the straight line B, that is, if it is determined to be located between the straight line A and the straight line B, which is the target track, the deceleration force is not adjusted.
The optical head is positioned between the straight lines A and B. When moving the optical head to the adjacent track in this way, accelerate the distance to the adjacent track, for example, 1/2 the distance to the adjacent track, to move the optical head in a predetermined time, and obtain the difference obtained by moving the optical head. Since the deceleration force of the optical head is controlled based on the detection result of detecting the inflection point of the signal, even if the sensitivity of the actuator that causes the optical head to jump to the next track varies, The optical head can be jumped to the track.

Further, the acceleration time is not unreasonable, and the optical head can smoothly perform the jumping operation without being affected by the external impact. In this embodiment, the optical head is accelerated until it reaches half the distance to the adjacent track, but this is an example, and the distance is not limited to 1/2.

[0023]

As described above in detail, according to the present invention, when the optical head is moved to the adjacent track, the optical head is accelerated to the middle of the distance for moving the optical head to the adjacent track,
Since the deceleration signal that decelerates the optical head is controlled based on the detection result of the detection of the inflection point of the signal related to the signal detected by the optical head, the sensitivity of the actuator that causes the optical head to jump to the adjacent track Even if there are variations, the optical head can jump to the adjacent track in a predetermined time. Further, there are excellent effects such that the acceleration time is not unreasonable and the optical head can perform a smooth jumping operation without being affected by an external impact.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an optical disc device according to the present invention.

FIG. 2 is a flowchart showing the control contents of the CPU.

FIG. 3 is a waveform diagram showing changes in the difference signal corresponding to the moving state of the optical head.

[Explanation of symbols]

 2 Optical disc 3 Objective lens 5 Actuator 6 Differential amplifier 7 Servo circuit 8 Zero cross detection circuit 9 Inflection point detection circuit 11 Timer 12 Acceleration signal generation circuit 13 Deceleration signal generation circuit 14 CPU PH Optical head

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kyosuke Yoshimoto 8-1-1 Tsukaguchihonmachi, Amagasaki-shi, Hyogo Sanryo Electric Co., Ltd. Industrial Systems Research Institute

Claims (1)

[Claims] 1. An optical disk apparatus in which an optical head for projecting a light beam onto an optical disk is jumped to an adjacent track by an actuator, and means for generating an acceleration signal to be supplied to the actuator to accelerate the optical head. A means for measuring the moving time to the middle of the distance the optical head moves to the adjacent track, a means for controlling the deceleration signal supplied to the actuator to decelerate the optical head, and a means after the deceleration signal is supplied. Means for detecting an inflection point of a signal related to the signal detected by the optical head, accelerating the optical head by generating an acceleration signal for making the moving time a predetermined time, and decelerating from the end point of acceleration. The deceleration signal is controlled based on the detection result of the inflection point of the difference signal. Disk apparatus.