JPS59191147A - Objective driving device - Google Patents

Abstract

PURPOSE:To control an objective more correctly in both focussing and tracking directions, by installing a parallel plate spring and pivot bearings to an objective driving device and lightening the mass of the driving section against an elastic member. CONSTITUTION:To a sliding member 18, into which a pivot bearing 17 is press- inserted, one end of the parallel plate spring 19 of an elastic supporting member which supports the movement of an objective 9 in the F-direction is fixed. When an electric current is made to flow to an F-movable coil 11, force is produced in the F-direction and the parallel plate spring 19 becomes a supporting member, and then, the objective 9 is moved in the F-direction while its B-surface is kept parallel to the A-surface of a base body 21. Moreover, when an electric current is made to flow to a T-movable coil 12, the objective 9 is moved in the T-direction around the P-point of pivot bearings 15-17. By using the parallel plate spring for the supporting member of F-direction only, the burden to the plate spring is reduced and the mass of a movable section supported by the plate spring is reduced, and therefore, responses at higher frequencies are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention records high-density digital symbols on a disk-shaped recording medium and optically records information by projecting a light spot onto an information track. In a playback device that reads the information track, the position of the objective lens is adjusted relative to the disk surface in order to control the position of the optical subsystem 7 in accordance with the signal of the information track. This relates to an objective lens 7 driving device used for control purposes.

More specifically, for example, during the rotation of the disk, the deviation of the information track with respect to U, Llj; 4. Interlocking the rotation of In response to the vibration of the disk controller that occurs in
Focus control is performed to control the distance between the objective lens and the information track position.

In general, this optical reading device ('@ ((i) A video disk on which a video signal is recorded, and a digital audio disk on which an encoded audio signal is recorded.
In addition to being adopted for discs, it has also been applied to many other high-density information recording and playback devices.

This involves recording encoded video signals, audio signals, and various information on a disk as an information trunk, and then rotating this disk to emit light from a light source such as a ray → F ray. The original recorded information is reproduced by focusing the reflected light onto an information track on the disk and reading the reflected light from the disk surface.

This optical information reading device can record information at an extremely high density, and has the advantage of being able to record with higher precision and higher performance than conventional analog methods.
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Since the width and pitch of the information track are extremely small, this high-density '1゛^+1. ) in order to faithfully reproduce the light (10/1 m to 0.05/Z m).
), and therefore, in order to follow the total market price of the light spot, the speed, but also the speed, must be changed to the city noise (: ni 1 drive - suke city 1 j!) while: 41 In order to solve this problem, conventional methods have been to electrically detect the nososcopic light emitted from the TiSF surface and control the reading light spot position to match the information track position. .

As an example of the conventional method, the objective lens, or its holding frame, is constructed of two leaf springs parallel to the disk by an elastic support part 4J made of a leaf spring, and seven mechanisms are used. Let's drive according to the Wu difference number! :The holding frame that holds the objective lens and the parallel plate spring is made up of two plates perpendicular to the disk, the other end of which is fixed to the identification end, and driven according to the tracking error signal. A method has been proposed to do this.

However, in this conventional method, the support surface +il (two parallel plate springs) in the tracking direction supports the weight of the objective lens (or its holding frame) and the plate spring in the focus direction, so the mass is Big things: 1. Because of this, there is a problem that the response at the active frequency deteriorates.In addition, the bullet/leaf support part 4 in the tracking direction
) Jitter There is an ode to J that changes over time in one direction (directions other than the focus direction and dragging direction), causing the objective lens to tilt and making it impossible to read the information densely packed on the disk. .

OBJECTS OF THE INVENTION The present invention eliminates these drawbacks and provides an objective lens driving device that allows more accurate control of the objective lens in both the focusing and tracking directions and has a simple construction.

Structure of the Invention The present invention is an objective lens and a driving device equipped with a parallel plate spring and a pivot bearing, and by reducing the mass of the first drive force with respect to the elastic part, it can be used in both the claw and tracking directions.・Explanation of an embodiment that allows more accurate control of the object lens The details of this invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 shows a principle diagram of the magnetic circuit of the present invention. The movable coils 1 and 2 are directly bonded to Ij. Unfortunately, the 11-coil 1.2 is supported by a support structure (not shown in Figure 1) that can move in any direction between the F ()A-cus) direction and the T (tracking) direction. It is assumed that there is

The fixed magnet 4 faces the yoke 3 and is magnetized to have north and south poles so that lines of magnetic force exist in the %NAα direction.

The moving coil 1 is wound perpendicularly to the F direction, and the moving coil 2 is wound perpendicularly to the T direction. The useless moving coils 1 and 2 maintain a constant magnetic air gap between the fixed magnet 4 and the yoke 3 as shown in the figure. This yoke is more efficient if it uses a magnetic material such as permalloy, but it may also be made of a non-magnetic material.

In the above configuration, when a current is passed through the moving coil 1 in the arrow direction F, the current flows in the T direction, and due to magnetic action,
The movable coil section moves in the F direction.

Further, when a current in the arrow IT force direction is passed through the moving coil 2, the current flows in the F direction, and the -jrT moving coil portion moves in the T direction due to the magnetic action.

FIG. 2 shows a principle diagram of the support structure.

The 21st line Ia shows the principle of opposing parallel plate springs. When the l-j drive unit 5 moves in the F direction, a moment M is generated in the plate spring 6, and -M7 is generated at the end of the 4th spring. arise,
When using the same type of coil spring as leaf spring 6.7, M6. -M71d;, they cancel each other out, and the movable part 5 always moves parallel to the broken line F1.

Figure 2 b'''''C shows movement in the F force direction, 50
The two points are supported by a pivot bearing with low rolling friction and low resistance, and the point P is moved in the direction of force F.

If this point P is positioned with respect to the disk as shown in FIG. 2C, tracking IfII can be controlled for the information on the disk without causing jitter to be tilted in one direction.

FIG. 3 shows a specific embodiment of the present invention.

Pair Qh L to focus the light spot on the disk surface
/n, +9'd is fixed to a bobbin (not shown) made of a rigid body. The size is F on the bobbin.
F1-iJ moving coil for moving in the force direction11. F
The TiIJ moving coil 12 that is to be moved in the force direction is wound in a solid layer. 13 is a yoke, and a macnet 14 is fixed to one end of the yoke. F'jiJ moving coil 11 and T
One drive coil 12 is located between the yoke 13 and the macnet 140 with a constant magnetic air gap maintained.
15 is the nose, 16 is the nut, 17 is the pivot bearing, and 15 to 17 are the pivots that allow movement in the F force direction)
Form a +Imb receiver.

Reference numeral 18 denotes a sliding member into which the pivot bearing 17 is press-fitted, and one end of a parallel leaf spring 19, which is an elastic support member that supports movement in the F force direction, is fixed to the sliding member 18. 2
0 is north 15. It is a pivot bearing base to which the nut 16 is attached, and 20a is a screw that fixes the base body 21 and the pivot bearing base 20, and 212L is a screw that fixes the base body 21 and the pivot bearing base 20. York 13
This is a screw that determines f'It. The missing 22 is the base body 21
This is a light flux hole opened in the lens 9, and is located directly below the objective lens 9.

The operation of the objective lens driving device of this embodiment constructed as above will be explained below. When a current is passed through the OF iTJ moving coil 11, a force is generated in the F force direction as explained in FIG. , the parallel plate pie 19 becomes a supporting member,
Principle As explained in FIG. 2a, the B plane of the objective lens 9 moves in the F force direction while remaining parallel to the A plane of the base body 21. Current is applied to the drive coil 12 as fAt i-, and points P of the pivot bearings 15 to 17 are
Then, the objective lens 19i: moves in the F force direction.

As described above, according to this embodiment, by using the parallel plate spring only for the support r'rB 471 in the F force direction, the negative 41 force on the plate spring can be reduced, and the jitter change over time in one direction can be reduced. can do. Furthermore, since the weight of the movable part supported by the leaf spring is reduced, response at high frequencies can be improved.

Effects of the Invention The present invention (/l: Y, by using a parallel plate spring for the support part A in the F force direction and using a pivot l-1 fb support for the support in the F force direction, the load on the plate spring can be reduced. , junior high school children,
V) An excellent objective lens that makes it possible to make the TL-ji+ lighter, improves response at high frequencies, and reduces unidirectional changes in iiJ motion jitter over time. This makes it easier to realize a drive device.

[Brief explanation of the drawing]

Figure 1 (r-1, principle diagram of the magnetic circuit of the present invention, Figure 2 a)
~C( is a principle diagram of the support structure of the present invention, and FIG. 3 is a perspective view of the objective lens 11 double-acting device in one embodiment of the present invention. 1.2, 11.12... Moving coil, 4 ,1
4...McNett, 3,13 ・York, 5
・-・Movable part (hohin), 6, 7.19 ・・Movement plate blade, 8 ・・Fixed end, 9 ・・Objective lens, 16, 1
6゜17... Pivot bearing, 18... Sliding part,
20... Pivot-store stand, 21... Base body, 2
2...Light flux hole.

Claims (1)

[Claims] The objective range is attached to one end, and the other end is fixed to the mutually parallel surfaces of the intermediate support with a parallel leaf spring and a pivot 1 arranged at an angle of 9Q degrees with respect to the above-mentioned temporary spring.
By displacing the above sentence (①) in the direction of 7N 71i + 1 by the parallel plate spring and the pivot 1 IJ holder, the objective lens can be changed to 11:1 to 9.
Objective lens, drive model 1, characterized by being able to move in two axial directions without making an angle of 0 degrees.