JPS61265732A - Mounting part of objective lens - Google Patents

Abstract

PURPOSE:To set an objective lens to a prescribed position with high accuracy simply by providing a V-shaped groove at the peripheral of a lens frame of an objective lens and providing a projection energized elastically toward the V-shaped groove to a prescribed position on a moving member. CONSTITUTION:The V-shaped groove 15 is formed along the peripheral of the lens frame 50b. On the other hand, at a prescribed position of a tracking plate 80 being a moving member, a part of the tracking plate 80 is notched and bent in V-shape and a projection 85 being a projection body is projected inward and an elasticity is provided by the characteristic of the elastic material of the tracking plate. Several projections 85 are provided at an equal interval on a cylindrical tracking plate 80. In providing the structure above in advance, the lens frame 50b is inserted to the tracking plate 80 and then the projection 85 is engaged smoothly with the groove 15 along the V-shaped slope and fixed. Since mechanical engagement exists between the members, the optical perfor mance of the objective lens is not damaged because of an unexpected stress.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an objective lens mount, and more particularly to an objective lens mount that can be applied to optical disc devices, video disc devices, and the like.

(Prior Art) FIG. 4 shows a drive mechanism for a semiconductor head for a source disk suitable for actual winding of the present invention. The outline of its operation is as follows.

Laser light emitted from the semiconductor laser 1 is reflected by the beam splitter 2, passes through the collimating lens 3 and the quarter-wave plate 4, and is focused onto the disk 6 by the objective lens 5L. The return source reflected by the disk 6 is the objective lens 5a.

The light travels backward in the order of the quarter-wave plate 4, collimator lens 6, and beam splitter 2, and then advances to the 4-split photodiode 7.

Here, focusing control to align the laser beam to a required focal position on the disk 6 is performed by inputting and controlling the signal received by the 4-split photodiode to the coil 12Vc via a control circuit (not shown). .

The configuration for performing focusing control is as follows. That is, the objective lens 5a is composed of a lens and a cylindrical lens frame piece that supports the lens, and is fitted with a cylindrical tracking plate 8 with high precision and fixed with an adhesive. Is the tracking plate 8 a leaf spring 9? It is supported in a floating manner by the housing 10 via the housing 10. The objective lens 5 is controlled for focusing by being slightly moved vertically by a magnetic force acting between a magnet 11 fixed to the housing 10 side and a coil 12 fixed to the tracking plate 8 side. This is the reason.

By the way, as mentioned above, adhesive is conventionally used as a means for attaching the lens frame of the objective lens 5a to the tracking plate 8, but with this method, stress caused by adhesive distortion, shrinkage, etc. There is a problem that the optical performance of the lens 5a is affected.

(Objective) Therefore, an object of the present invention is to provide an improved objective lens attachment part that allows the objective lens to be easily and highly accurately set at a predetermined position.

(Structure) In order to achieve the above object, the present invention includes a V-shaped groove formed on the outer periphery of the lens frame of an objective lens, and a movable member that is positioned at a predetermined position on the movable member, and that is positioned in the V-shaped groove. The object lens is characterized in that a mounting portion for the objective lens is configured in combination with a convex body that is elastically biased toward the objective lens.

Hereinafter, the present invention will be specifically explained based on one embodiment.

Example 1 [See Figure 1].

Figure 1 shows an enlarged view of the attachment part of the objective lens.
A V-shaped groove 15 is formed along the outer circumference of the lens frame 50b.

On the other hand, a part of the tracking plate 800, which is a movable member, is cut into a predetermined portion, and is bent into a V shape so that a convex portion 85 as a convex body protrudes inwardly. It is elastically biased due to the elastic material properties of the tracking plate.

The convex portions 85 are provided at several locations on the cylindrical tracking plate 80 at equal intervals.

If such a structure is provided in advance, by inserting the lens frame 50b into the tracking plate 80, the convex portion 85 can be smoothly engaged with the groove 15 and held along the V-shaped slope. Become. In this example, unlike the prior art, mechanical members are engaged, so that the objective lens is not subject to unexpected stress and loses its optical performance (1° Embodiment 2 (see Figures 2 and 3)) .

In this example, a lens frame 50b that is completely the same as in the previous example is used. On the other hand, regarding the tracking plate 80'.

Unlike the above example, a convex portion 85' protrudes outward, and a 7-shaped concave portion 85 is formed on the back side of this convex portion 85'.

To attach the objective lens, a sphere 90 made of an elastic material (synthetic resin material) is held in the recess 85i in advance, and then the lens frame 50o is inserted into the tracking plate 80' and the convex body is The groove 15 is locked through the sphere 85'eL.

Grease or the like can be used as a means to hold the sphere 90 in the recess 85'f? You may use it or you may fix it with adhesive.

Also in this example, the lens frame 50b can be positioned at a predetermined location simply, quickly, and with high precision.

Note that the present invention can also be applied to an objective lens of a microscope.

(Effects) According to the present invention, the objective lens can be installed easily and with high precision, and can also be easily disassembled if necessary. or,
Compared to the conventional technology, there is no effect of adhesive (including press-fitting), and therefore the deterioration of the optical performance of the objective lens is improved.

[Brief explanation of drawings]

Figures 1 and 2 are cross-sectional views of the attachment part of the objective lens, each explaining an embodiment of the present invention, Figure 3 is a partial perspective view of the tracking plate in Figure 2, and Figure 4 is a partial perspective view of the tracking plate in Figure 2. FIG. 3 is a cross-sectional view of an optical head drive mechanism suitable for carrying out the invention. 5a...Objective lens, 50o...Mirror frame, 15...
V-shaped groove, 80.80'...Tracking member, 8
5... Convex portion as a convex body, 90... Sphere as a convex body. 2 diagrams 4 diagrams

Claims (1)

[Claims] A means for assembling an objective lens to a movable member movably supported with respect to a housing, the objective lens being positioned by a V-shaped groove formed on the outer periphery of the lens frame and a predetermined position on the movable member, and a convex body elastically biased toward the V-shaped groove.