JPS62293526A - Lens vibration preventing device - Google Patents

Abstract

PURPOSE:To attain high speed for track access by simple circuit forming by differentiating an output of a speed detector of an optical head moving device and using the output so as to control an actuator current thereby suppressing the vibration of a lens. CONSTITUTION:A differentiation circuit 8 of an optical head moving device differentiates a generated voltage corresponding to the moving speed of a speed detector 7, the result is inputted to a drive amplifier 6 via a switch 5 to drive a lens actuator. Since the actuator is supported by a spring in this case, vibration is generated at acceleration/deceleration. Then the output of the detector 7 is differentiated (8) to obtain acceleration to control the actuator current by the output of the amplifier 9. Then the acceleration equal to that generated by the optical head moving mechanism is generated in the actuator in a direction cancelling the vibration of the lens to suppress the displacement of the lens. Thus, the track access is quickened by the simple circuit forming.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a one-to-one tracking control device for a lens of an optical information recording/reproducing device.

[Prior Art] Conventionally, in this type of track following control device, when moving the beam spot onto the target i-rack, the optical head moving mechanism performs rough positioning, and the lens moves to position the beam spot from target 1 to rack. However, this movement of the optical head causes the lens to vibrate due to acceleration during rough positioning by the structure, and when performing a truck retracting operation, the trunk retracting operation must be performed after waiting until the vibration of the lens has subsided.

[Problems to be Solved by the Invention] In the conventional track following control device described above, when moving the optical head moving mechanism to perform rough track positioning, the objective lens is supported by a spring, so the lens is distorted due to the acceleration during movement. The lens vibrates, and even after the optical head moving mechanism has stopped, the lens continues to vibrate, which blurs the relative position of the lens and the optical head moving mechanism, causing misalignment of the optical axis and deterioration of optical characteristics, as well as the tracking caused by the lens. When performing retraction operation, the track retraction becomes unstable due to vibration, so
There was a drawback that it was necessary to wait until the vibration disappeared, which increased the time it took to access the track.

An object of the present invention is to provide a lens shake prevention device that enables high-speed track access.

[Means for Solving the Problems] The lens shake prevention device of the present invention includes an optical head for optically recording and reproducing information, a speed detector attached to an optical head moving mechanism, and an output of the speed detector. , a switch that receives the output of the differentiation circuit and turns on when the optical head moving mechanism moves, and a drive circuit that drives the optical rad actuator using a signal from the switch. It is something to do.

[Example] Next, an example of the present invention will be described with reference to the drawings.

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

The output of the two-split photodetector 1 is subtracted by the differential amplifier 2 to become an error signal, which is then sent to the phase compensation circuit 4. The signal is inputted to the drive circuit 6 via the switch 5. The output of the drive circuit 6 is connected to the tracking actuator of the optical head, and drives the tracking actuator according to the error signal.

On the other hand, a speed detector 7 attached to the optical head moving mechanism
A voltage corresponding to the moving speed is obtained, and this signal is differentiated by a differentiating circuit 8 and then passed through a switch 5 to a drive circuit 6.
is input to drive the lens actuator. Here, the switch 5 is operated so as to be connected to the phase compensation circuit 4 during track following operation, and connected to the amplifier 9 when the optical head moving mechanism is moved.

Next, Figure 2 (a), (b), (C), Figure 3 (a)
), (b).

(C), (dL) The operation will be explained with reference to (e).

2(a), (b), and (c) are cases where the present invention is not applied, and (a) shows the acceleration of the optical head moving mechanism, (
b) shows the speed of the optical head moving mechanism, and (C) shows the lens position of the optical head. When the acceleration shown in (a) is applied to the optical head moving mechanism, the speed at this time becomes as shown in (b). At this time, since the lens actuator of the optical head is supported by a spring, vibrations are applied during acceleration and deceleration, and the lens position changes as shown in (C). The acceleration at this time is α
, if the mass of the lens is M and the spring constant is Kx, then
It will be displaced only by X=Mα/. Here, if the acceleration is O, it will vibrate at the natural frequency of the spring. This vibration occurs when performing track retracting operation.
Track error caused by misalignment between the lens and the optical axis appears as an offset shift in the signal, a reduction in signal quality, and a fluctuation in the pull-in speed during track pull-in, which is detrimental to stable track pull-in operations. In this case, it is clear that lens vibration must be suppressed.

Figure 3 (a), (b), (c), (d), (e
) C shows a case where the present invention is applied.

(a) is the acceleration applied to the optical head moving mechanism, (b)
is the output of the speed detector 7, and (C) is the output of the differentiating circuit 8.

Differentiating the output of the speed detector 7, where the speed is d
Acceleration is determined from /dt-α.

Here, in order to eliminate lens shake, the lens actuator should generate an acceleration equal to the acceleration generated by the optical head moving mechanism in a direction that cancels out the lens shake, so the force constant of the actuator is KF,
If the current flowing through the lens actuator is i, then i=M
・It is sufficient to flow a current of α/KF. Therefore, K
=M/KF, the amplification factor of the drive amplifier 6 is 1 [A/v
1, it can be seen that the shake of the sharpening lens, which is twice the amplification factor of the amplifier 9, is eliminated. Here, in Figure 3 (C
) is the output of the differentiating circuit 8, and (d) is the output of the amplifier 9, which is always multiplied by (d). (e) shows the lens position, and it can be seen that the displacement of the lens is suppressed by causing the lens actuator to generate an acceleration equal to the acceleration generated by the optical head moving mechanism.

[Effects of the Invention] As explained above, the present invention only differentiates the output of the speed detector used to control the speed of the optical head moving mechanism and controls the actuator current using this output, so it is a very inexpensive circuit. Since the acceleration applied to the lens is detected from the actual operation of the optical head moving mechanism, it is possible to accurately detect it, keep lens shake to a very small level, and track it until the lens shake is stabilized. This has the effect of realizing high-speed track access without the need to wait for the vehicle to be pulled in.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2(a)
, (b), (C) are explanatory diagrams of lens shake, and Figure 3 (
a), (b), (C), (d), and (e) are operation explanatory diagrams when the present invention is applied. 1...2-split photodetector 2...Differential amplifier 4...
・Phase compensation circuit 5...Switch 6...Drive amplifier 7...Speed detector 8...Differential circuit
9...Amplifier patent applicant Nippon Electric Engineering Co., Ltd.Illustration 1

Claims (1)

[Claims] (1) An optical head that optically records and reproduces information, a speed detector attached to the optical head moving mechanism, a differentiating circuit that differentiates the output from the speed detector, and a differential circuit that receives the output of the differentiating circuit. A lens shake prevention device comprising: a switch that is turned on when an optical head moving mechanism moves; and a drive circuit that drives an actuator of the optical head based on a signal from the switch.