JPS634269Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an actuator for an optical pickup, and in particular, a braking slide having a U-shaped cross section and an opening facing downward is provided at the top of a moving body that freely moves in vertical and horizontal directions. This invention relates to an actuator for an optical pickup equipped with an oil scattering prevention device.

Taking an actuator, for example, an actuator of an optical pickup of a video/audio disc player, as an example, elastic support of the actuator will be explained with reference to FIG.

The elastic support has a longitudinal direction parallel to the tracking movement direction (X-axis direction) and is attached to the base 1A of the housing 1.
A pair of square rod-shaped focus drive permanent magnets 2 consisting of a permanent magnet piece 2A and a magnetic piece 2B fixed to
A rectangular focus control coil 3 is disposed in the cavity 2C and is provided around the objective lens 4.
is arranged in the gap 6A between the other end of the objective lens holder 5 attached to the center and a pair of tracking drive permanent magnets 6 whose longitudinal direction is parallel to the tracking movement direction and fixed to the base 1A of the housing 1. The objective lens holder 5 can be moved vertically by a parallel plate spring 9 for focusing, which is installed on the upper and lower surfaces of the other end of the tracking moving body 8, around which a rectangular coil 7 for tracking control is wound. It is elastically supported by a tracking parallel plate spring 10 whose central part is fixed to the side walls at both ends of the tracking movable body 8, and whose both ends are fixed to both side walls 1B parallel to the tracking movement direction of the housing 1. This is done by elastically supporting the objective lens holder 5 freely in the left-right direction via the focus parallel plate spring 9.

When metal plate springs are used as the focusing parallel plate spring 9 and the tracking parallel plate spring 10, which are the elastic supports of the actuator, if braking is not applied, the resonance peak will be large as shown by the solid line in Figure 2. Therefore, the fact that this resonance peak is large itself makes it difficult to control when the resonance peak frequency and resonance peak value change due to temperature change or the like. Therefore, as shown in FIG. 3, for example, the gap 2C of the focus drive permanent magnet 2 is filled with viscous lubricating oil 11 for braking using capillary action.

However, in this prior art, in the case of low-speed driving, although the braking oil 11 does not scatter,
In the case of high-speed driving (large amplitude and high frequency), the braking lubricant 11 is scattered outside, for example, on the upper surface of the magnetic piece 2B. As a result, if the braking oil 11 becomes insufficient, a problem arises in that the resonance peak becomes large and the control system becomes unstable.

This idea was devised by focusing on the problems of the conventional technology, and includes a braking lubricant having a U-shaped cross section and an opening facing downward at the top of a moving body that moves vertically and horizontally. The purpose is to solve the above-mentioned problems by attaching a scattering prevention device.

This invention will be explained below based on the drawings.

FIG. 4 is a schematic exploded perspective view of an actuator for an optical pickup to which this invention is applied.

Reference numeral 20 denotes a brake lubricant scattering prevention device, which is mounted on the upper part of the objective lens holder 5, which is a movable body that can freely move vertically and horizontally. The brake oil scattering prevention device 20 is formed of a horizontal piece 21 and a pair of vertical pieces 22, and has a U-shaped cross section and opens downward. The horizontal piece 21 is attached to the upper surface of the objective lens holder 5, and a circular hole 21A is bored in the center of the horizontal piece 21 so that the objective lens 4 attached to the center of the objective lens holder 5 protrudes. ing. The length l ₁ of the horizontal piece 21 is such that the longitudinal direction is parallel to the tracking movement direction (X-axis direction) and the housing 1
It is disposed in the gap 2C of a pair of rectangular bar-shaped focus drive permanent magnets 2 made up of a permanent magnet piece 2A and a magnetic piece 2B fixed to a base 1A of The length l2 of the focus control rectangular coil 3 is set to be greater than ₂ , and the distance d between the vertical pieces 22 is
It is set larger than the width w of the focus control rectangular coil 3.

Note that parallel plate springs 9 for focusing are attached to the upper and lower surfaces of the square frame-shaped tracking moving body 8, and between the parallel plate springs 9 for focusing, a lubricating oil scattering prevention device 20 for braking, an objective lens holder 5, and a focus plate spring 9 are attached. A control rectangular coil 3 is attached. Also,
Parallel plate springs 10 for tracking are attached to both side walls of the tracking moving body 8. Furthermore, a circular tracking control coil 71 is provided protruding from one side wall of the tracking movable body 8.
A circular tracking drive permanent magnet 61 is fixed to the side wall of the housing 1.

When the objective lens holder 5 moves in the vertical direction, when the braking oil filled in the gap 2C of the focus drive permanent magnet 2 scatters upward,
The horizontal piece 21 prevents scattering. Further, when the objective lens holder moves in the left-right direction and the braking lubricating oil scatters in the left-right direction, the vertical piece 22 prevents it from scattering.

As explained above, this invention is based on attaching a braking oil scattering prevention device having a U-shaped cross section and an opening downward to the top of a moving body that can freely move vertically and horizontally. As a result, it is possible to prevent the braking oil from scattering as the moving body moves in the vertical and horizontal directions, thereby achieving the effect that the resonance peak can be reduced and the control system can be stabilized.

[Brief explanation of drawings]

Fig. 1 is a schematic exploded perspective view of the actuator of a conventional optical pickup, Fig. 2 is a diagram showing the relationship between frequency and gain, Fig. 3 is a diagram with brake oil filled in the gap, and Fig. 4 1 is a schematic exploded perspective view of an actuator of an optical pickup to which this invention is applied. 1... Housing, 2... Permanent magnet for focus drive, 3... Square coil for focus control, 4
...Objective lens, 5...Objective lens holder, 6...
... Permanent magnet for tracking drive, 7 ... Rectangular coil for tracking control, 8 ... Tracking moving body, 9 ... Parallel leaf spring for focusing, 10 ... Parallel leaf spring for tracking, 11 ... Lubricating oil for braking,
20...braking oil scattering prevention device, 21...horizontal piece, 22...vertical piece.

Claims (1)

[Scope of utility model registration request] A square focus control coil protrudes from the gap between a pair of square bar-shaped focus drive permanent magnets whose longitudinal direction is parallel to the tracking movement direction and is made up of a permanent magnet piece and a magnetic piece fixed to the base of the housing. The objective lens is attached to the center and can be moved freely in the left and right directions by parallel plate springs for tracking.The parallel plate springs for focus provided on the upper and lower surfaces of the tracking moving body allow it to move freely in the vertical and horizontal directions. An actuator for an optical pickup comprising a braking oil scattering prevention device having a U-shaped cross section and an opening facing downward, mounted on the top of a moving body that moves.