JPS61273753A - Objective lens supporting device for optical pickup - Google Patents

Abstract

PURPOSE:To perform fast retrieval by providing a driving means which displaces an objective lens in its optical-axis directions or at right angles to them and a viscous body charged in the gap between a movable part and a fixed part. CONSTITUTION:A focus coil 5 is wound around a lens holder 8 and a radial coil 6 wound in a flat plate shape is fitted to its periphery. A center pole 4 is fitted in a hole 11 and the viscous body 13 is charged in the gap between the hole and center pole 4 and uses, for example, silicone gel which has enough viscosity not to flow out of the gap and is extremely soft. Magnetic flux produced by the magnetic circuit composed of a permanent magnet 2, a yoke 3, and the center pole 4 and a current flowed to the focus coil 5 and radial coil 6 are adjusted to drive the lens holder 8 including the objective 1. Consequently, the weight reduction of an optical pickup device and superior attenuation effect are realized and fast control is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an objective lens support device for an optical pickup that records and reproduces information on and from an optical recording medium C2.

[Technical background of the invention and its problems]

High-density recording and reproducing devices using laser light, which have been put into practical use in recent years, generally record information such as audio and images in micro grooves in a spiral or concentric circle on a rotating recording disk. It is read using the diffraction phenomenon of laser light, which is coherent light that is controlled to focus on this groove. Another method is to record space information on the grooves using the energy of laser light.

A device similar to this uses laser light to create fine grooves:
Accurate (=focusing) is one of the important techniques.Especially when used as an external storage device for computers etc. for high-speed recording and high-speed reproduction of large amounts of information such as image information, It is necessary to reduce recording/reproduction errors as much as possible. To this end, accurate and stable two-dimensional control of the objective lens over a wide frequency band is required.

Furthermore, searching for recorded information quickly is an important technical problem for high-speed computer information processing. This high-speed retrieval of information on a recording medium requires rapid switching of the objective lens position from one groove to another, and then to another groove. At this time, the objective lens needs to be rapidly accelerated and stopped, and during acceleration, it is given mechanically large kinetic energy.

This becomes an obstacle when position control, once removed, is quickly restored to a controlled state at the target groove.

FIGS. 4 and 5 below show examples of objective lens support devices that are ready for practical use.

Figure 4: Objective lens 1, focus drive coil 5, radial drive coil 6, and lens holder 8
is supported by the fixed plate 9 by four parallel elastic support members 7. This elastic support member 7 is made by covering the lead wire of the coil, a metal wire which also serves as a support spring, and a rubber tube to add a damping effect. Further, the driving force is obtained from the magnetic flux of the magnetic circuit consisting of the permanent magnet 2, the yoke 3, and the center ball 4, and the abrasive current C flowing through the driving coil 5.61.

In FIG. 5, as the elastic support member 7, a parallel plate spring for focusing and a cross plate spring for radial are connected by a relay member 10 and fixed to a fixed plate 9. In each of the leaf springs, the same reference numerals are given to the plate-like parts, and the explanation thereof will be omitted.

In this way, whether the elastic support member 7 is a beam-shaped metal wire or a plate spring, the curvature of the bending deformation of the elastic support member 7 is minute, so the rubber tube or the like that deforms accordingly. The deformation of each part of the damping sheet is also minute 1, so the damping effect is not sufficient, and only increases the mass of the support member and the spring constant of the entire support mechanism. As described above, a recording/reproducing apparatus using an optical pickup having an objective lens support structure cannot sufficiently absorb the large kinetic energy received during high-speed retrieval, making high-speed control difficult. Moreover, the support structure using metal wires and temporary springs is
Due to the large number of parts and the complexity of the structure, assembly work is difficult, which is also the cause of the loss of Ji mass production.

[Purpose of the invention]

The invention was made in view of the above circumstances, and in order to enable high-speed retrieval, the kinetic energy stored in the movable parts including the objective lens is attenuated at an appropriate speed. It is an object of the present invention to provide an objective lens support device that can be mass-produced through improvements.

[Summary of the invention]

In order to achieve the above object (-1) in the present invention, an objective lens, a holder for holding the objective lens, and a movable part including the lens holder are connected to a fixed part consisting of a base at least for light of the objective lens. A driving means for moving and displacing in the axial direction or in a direction perpendicular to the optical axis direction;
An objective lens support device for an optical pickup is provided, characterized in that it includes a viscous material that fills a gap between a movable part and a fixed part.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to CC drawings.

FIG. 1 is a perspective view of one embodiment of the entire optical pickup having an objective lens support device of the present invention, and FIG. 2 is a sectional view thereof.

In FIGS. 1 and 42, an objective lens 1 is held at the center of a lens holder 8, and holes 11 are provided at both longitudinal ends of the objective lens 1. Further, a focusing coil 5 is wound around the lens holder 8.
A radial coil 6 wound into a flat plate shape is attached to its surroundings (: indicates a center hole 11 (: indicates a center protruding from the base 12 with a gap greater than the movable distance of the objective lens l). The ball 4 is fitted into the hole 11.
A viscous body 13 is filled in the gap between the center ball 4 and the center ball 4, and is supported by the viscous body 13. −
The viscous material 13 has a viscosity that does not flow out from the gap between the hole 11 and the center ball 4, and is very soft, such as silicone gel. When filling the gap with the viscous material 13, place a frame around the gap to prevent spillage, and remove the frame after the viscosity reaches a level where it will not flow out. good. A yoke 3 protrudes from the four corners of the base 12 at a position facing the center ball 4 and the radial coil 6, and a permanent magnet 2 is fixed on the surface of the yoke 3 facing the radial coil 6. There is. These are permanent magnets 2. York 3. The magnetic flux generated by the magnetic circuit formed by the center pole 4 and the focus coil 5. By adjusting the current flowing through the radial coil 6, it is possible to drive the lens holder 8 including the objective lens 1.

[Other embodiments of the invention]

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be modified in various ways without changing the gist thereof.

In the above embodiment, the gap between the hole 11 of the lens holder 8 and the center pole 4 was filled with the viscous material 13, but for example,
As shown in FIG. 113, the gap between the permanent magnet 2 and the lens holder 8 may be filled with a viscous material 13.

At this time as well, it is sufficient to surround the gap with a frame while the viscous substance 13 is melted to prevent it from spilling out, and remove the frame only after the viscosity reaches a level where it will not flow out.

In this case, the viscous body 13 will be interposed between the focus coil 5, the radial coil 6, and the permanent magnet 2.
The viscous body 13 is made of silicone gel or the like and does not have any influence on the magnetic flux 1; therefore, the driving force does not decrease.

In addition, a permanent magnet 2 is fixed to a lens holder 8 and a yoke 3ζ facing each other; a focus coil 5 and a radial coil 6 are provided.
The driving force may be obtained using a moving magnet method for winding the material.

〔Effect of the invention〕

As described above in detail, the f'L according to the present invention eliminates complicated assembly work by supporting the objective lens with a viscous material without using metal wires or plate plates as in the conventional method. At the same time, the weight of the optical pickup device can be reduced, a flattening effect can be obtained, and high-speed control can be achieved.

[Brief explanation of the drawing]

1 is an overall perspective view of an embodiment of the present invention; FIG. 2 is a sectional view of an embodiment of the invention; and the third factor is 1 a sectional view of another embodiment of the invention; FIG. 4 is an overall perspective view showing the first conventional example, and FIG. 5 is a perspective view of the first conventional example. FIG. 7 is an overall perspective view showing a second conventional example. 1... Objective lens 4... Center pole 8...
・Lens holder 12... Base 13... Viscous body agent Patent attorney Nori Keisuke Chika (and 1 other person) No.
1 figure

Claims (1)

[Claims] An objective lens, a lens holder that holds this objective lens, and a movable part that includes this lens holder are moved at least in the optical axis direction of the objective lens or in a direction perpendicular to the optical axis direction with respect to a fixed part that includes a base. 1. An objective lens support device for an optical pickup, comprising: a drive means for moving and displacing; and a viscous material filling a gap between the movable part and the fixed part.