JPS6246444A - Protecting device for objective lens - Google Patents

Abstract

PURPOSE:To prevent effectively an objective lens from the adhesion of dust by arranging rotatable protecting plate above the objective lens. CONSTITUTION:The protecting plate 3 fitting a magnet piece 4 to its one end is rotatably fitted to a rotary shaft of a protecting case 1 so as to cover the immediately apper part of the objective lens 6. A coil 5 is arranged near the magnet piece 4 and the protecting plate 3 usually cover the objective lens 6 by a spring 2 laid between the case 1 and the plate 3. At the time of reading operation, current is supplied to the coil 5, the magnet piece 4 is adsorbed and the protecting plate 3 is rotated, so that a laser beam is radiated. Consequently, the objective lens can be effectively prevented from the adhesion of dust.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an objective of an optical head that irradiates an optical video disk, CD optical disk, etc. with a fully condensed beam emitted by an optical head and reproduces a signal using the reflected or transmitted light. Related to Lens Protection Apparatus 0 Prior Art An example of a conventional objective lens protection apparatus will be described below with reference to the drawings. FIG. 7 shows an example of the optical system of the optical head, FIG. 8 is an exploded view of the conventional example, and FIG. 9 is a sectional view of the conventional example. In FIG. 7, the laser 51 emitted from the semiconductor laser element 16 [the collimating lens 15.
Grating 14, polarizing beam splitter 13.1/
4 Wave plate 12, fixed mirror 11. The light passes through the objective lens e, is reflected by the disk 10, passes through the beam splitter 13° lens system 17, enters the detector 18, and is converted into an electrical signal. Note that reference numeral 1 indicates an objective lens drive unit, 8 an optical case, and 1 a protective case for protecting the objective lens.

The objective lens protection device constructed as described above covers the entire optical head and a portion thereof with a cover having a hole for the objective lens. Therefore, the objective lens is simply prevented from touching the objective lens.

Problems to be Solved by the Invention However, with the above configuration, dust tends to adhere to the surface of the objective lens 6 exposed from the objective lens protection device, and a portion of the laser beam may be blocked or scattered by the attached dust. As a result, the amount of laser beam transmitted through the objective lens 6 is reduced. This allows detector 1
The electrical signal obtained from 8 is reduced. It is important to prevent dust from adhering to the objective lens 6 in this way.

However, if dust has adhered to it, the conventional method for removing this dust has been to wipe the entire surface of the objective lens 6 with paper or cotton.

Such a method requires manual implementation and is cumbersome.

In view of the above-mentioned problems, the present invention provides an objective lens protection device in which a protection plate is provided directly above the objective lens to prevent dust from adhering to the objective lens.

Means for Solving the Problems In order to solve the above problems, the objective lens protection device of the present invention includes a rotatable protection plate provided on the objective lens, a magnet piece arranged at the end of the protection plate, and a magnet. A coil is provided near one end, and the protection plate is configured to rotate around a part of the protection plate as a fulcrum to prevent dust and the like from adhering to the objective lens.

Function: According to the present invention, the protection plate rotates directly above the objective lens to prevent dust from adhering to the lens.

Embodiment Hereinafter, an objective lens protection device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an exploded perspective view of the basic structure of an objective lens protection device in a first embodiment of the present invention. In FIG. 1, 1 is a protective case that holds the protective plate 3;
3 is a spring that returns the protection plate 3 to a predetermined position, 3 is a protection plate placed directly above the objective lens, 4 is a magnet piece that applies rotational force to the protection plate 3, 6 is a coil that applies force to the magnet piece 4, and 6 is an objective lens. The lens, 7 is an objective lens drive unit, and 8 is an optical case, and the same parts as in the conventional example are given the same numbers and their explanations will be omitted.

Regarding the objective lens protection device configured as above,
The operation will be explained below using FIGS. 1 and 2.

FIG. 2 shows a cross-sectional view of the embodiment according to the present invention after assembly, and the protective plate 3 of the objective lens is usually located directly above the objective lens. In the case of an information signal reading operation, a current is applied to the coil 5 to attract or repel the magnet piece 4, and the protective plate 3 is rotated around the rotating shaft 9 to be removed from the objective lens and the laser beam emitted from the objective lens is directed onto the disk. Read the guess signal.

After reading the signal, the current to the coil is cut off.

Then, the force of the spring 2 automatically returns it to just above the objective lens, and it becomes a protective plate for the objective lens.

As described above, this embodiment prevents dust from adhering to the objective lens. In addition, there are other examples shown below.

FIG. 3 shows a second embodiment, in which a rotating magnet piece 4a is provided on the fulcrum shaft, and a coil 6 is provided around the rotating magnet piece 4a to allow the protection plate 3 to rotate fully. .

A spring 2ai is provided at the other end.

FIG. 5 shows a fourth embodiment, in which a magnet piece 4 larger than the width of the protection plate is provided at the end of the protection plate 3, and a hollow coil 6a is provided to surround the magnet piece, and a spring 2 is attached to the fulcrum. The setup is a friend.

FIG. 6 shows a fifth embodiment, in which a magnet piece 4 is arranged at the end of a protection plate 3, a coil 6b having an iron core 9 is arranged near the magnet piece, and a spring 2a is arranged near the magnet piece. be.

Effects of the Invention As described above, the present invention can prevent dust from adhering to the objective lens by using the protective plate provided directly above the objective lens in an optical head.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing the basic structure of an objective lens protection device according to a first embodiment of the present invention, FIG. 2 is a sectional view of FIG. 1, and FIG. A sectional view of the objective lens protection device, FIG. 4 is a layout diagram of the protection plate in the third embodiment, FIG. 6 is a layout diagram of the protection plate in the fourth embodiment, and FIG. 6 is a diagram in the fifth embodiment. Layout diagram of protection plate,
FIG. 7 is a schematic configuration diagram showing an example of the optical system of a conventional optical head, FIG. 8 is an exploded perspective view of a conventional objective lens protection device, and FIG. 9 is a sectional view of a conventional objective lens protection device. . 1... Protective case, 2, 2a... Spring, 3... Protective plate, 4, 4a... Magnet piece, 5.6 &. 5b... Coil, 6... Objective lens,
7...Objective lens drive unit, 8...Optical case, 9...Iron core, 10...Disc, 11...Mirror, 12・・・・・・1/4
Large plate, 13...Polarized beam splinter, 14
...Grating, 16...Collimating lens, 1e...Semiconductor laser element, 17...
...Cylindrical lens, 18...Detector,
19... Protective plate stop. Name of agent: Patent attorney Toshio Nakao and 1 other persona
l Figure 2 Figure 3rI! J Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] a radiation light source, an optical system that receives a light beam emitted from the radiation light source and guides it to an objective lens, a protection plate provided to cover the objective lens, a magnet piece disposed at an end of the protection plate, and the magnet 1. An objective lens protection device, comprising a coil located near one of the pieces, and rotating about one point of the protection plate as a fulcrum.