JPS61122947A - Optical head - Google Patents

Abstract

PURPOSE:To prevent the deterioration of converging performance of a fine spot of optical head by installing a heat flickering suppressing member at the light path between a fixed part and a moving part of a separating type optical head. CONSTITUTION:For the separating type optical head, a heat flickering suppressing member 15 is installed at a light path 12 between a fixed part 13 and a moving part 14. Thus, the light path 12 can be screened from the outside of the optical head and the deterioration of the converging characteristic of the laser due to influences of a heat flickering 11, a dust, etc., can be prevented. A notch 16, when the moving part 14 is shifted in the disk radial direction, makes a coming-out light from an objective lens 9 arrive at optical disk medium 1. By such a constitution, the influences of the heat flickering, dust, etc., are removed, a highly accurate error signal can be detected and the deterioration of the converging performance of the fine spot can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the configuration of a separate optical head having a fixed part consisting of an optical system such as a light source, and a movable part consisting of a mechanical device such as a light beam drive. It is something.

(Prior Art and Problems) An optical head is used in an optical recording device to record and reproduce optical information by forming a minute spot on a running recording medium.By driving the minute spot, the optical head performs focus following, track following, Perform track access. Typical optical head/
Example first! As shown in the figure. The optical disk / is rotated by a motor tacho, and the optical head 3 is driven in the radial direction of the optical disk to select a track.

In the example shown in Figure 5, the components of the optical head are the semiconductor laser μ and the coupling lens! , prism beam splitter B, //≠wave plate 7, optical path converting mirror ♂, condensing lens, and photodetector 10 are all housed in one case, and the whole moves in the radial direction of the disk. In this case, even if thermal fluctuations or dust occur outside the optical head, the optical path /2 will not be affected. However, this configuration has the drawback that the optical head becomes large, making it impossible to speed up track access. Therefore, in order to speed up track access, it is effective to reduce the weight of the movable part.

In another example of the optical head shown in FIG. 6, in order to reduce the weight of the movable part, a fixed part /3 consisting of an optical system such as a light source and a movable part l≠ consisting of a mechanical system such as a light beam drive are separated. It consists of In this case, since the optical path /2 is exposed to the outside of the optical head, it is affected by thermal fluctuation /l, dust, etc.
The objective lens has a disadvantage in that the light focusing performance of a minute spot focused on the disk medium l is degraded.

(Means for Solving the Problems) In order to eliminate these drawbacks, the present invention disposes a thermal fluctuation suppressing member in the optical path between the fixed part of the separated optical head and the movable part of the separated optical head, and This prevents deterioration of the light focusing performance of the head's minute spot. A detailed explanation will be given below with reference to the drawings.

(Example) FIG. 1 shows an example of the present invention. In this separated optical head, a thermal fluctuation suppressing member /J- is arranged in the optical path /2 between the fixed part /3 and the movable part 1. As a result, optical path 1
2 from the outside of the optical head, it is possible to completely prevent the deterioration of the focusing characteristics of the laser due to the influence of thermal fluctuations and/or dust. / is a cut for allowing the light emitted from the objective lens to reach the optical disk medium l when the movable part /≠ moves in the disk radial direction. /7(a) is the laser emission window of the fixed part /3 and /7φ) of the movable part /Hiroshi.

Also, /r(a) is a guide, 1rrb) is a carriage, and /r is a pedestal.

FIG. 2 shows another embodiment of the invention. The thermal fluctuation suppressing member 20 is made of a flexible member, and is a conduit-shaped thermal fluctuation suppressing member shown in FIG. It has a higher airtightness and is smaller than the previous model.

FIG. 3 shows another embodiment of the invention. The thermal fluctuation suppressing member is a band-shaped plate shown in 2/(a)tJ/Φ), and is disposed on both sides of the optical path /-. Although there is no cover for optical path/2 on the top surface, such a configuration is also simple and effective because the large part of thermal fluctuation can be prevented by the side plates.

Figure ≠ shows the optical path /2 in order to examine the function and effect of the present invention.
FIG. 4 is a waveform chart showing the results of reproducing data signals and track signals of an optical disk with and without a thermal fluctuation suppressing member by applying thermal fluctuation to the optical disc. In Figure 1 (a), which shows the case where there is no thermal fluctuation suppressing member, the temperature distribution in the optical path 12 generates a refractive index distribution in the air, which causes optical path distortion. For this reason, the optical spot on the disk medium/shape is distorted and the spot diameter is expanded, and as shown in FIG.
). On the other hand, when a thermal fluctuation suppressing member is provided, accurate data signals 22Cb) and tracking error signals 23(b) can be obtained as shown in FIG.

Note that the internal structure of the fixed part and the movable part of the optical head in the above embodiment is just one example, and the fixed part and the movable part can be separated as needed. The configuration can be changed freely.

(Effects of the Invention) As can be seen from the above description, the separate optical head of the present invention equipped with a thermal fluctuation suppressing member can remove thermal fluctuations, dust, etc., and achieve highly accurate error signal detection and stable It is possible to perform recording and playback.

[Brief explanation of drawings]

Figures 1, 2, and 3 are diagrams showing embodiments of the separate optical head of the present invention, Figure ≠ is a waveform diagram showing the effects of the present invention, and Figure 3 is a waveform diagram of the conventional integrated optical head. FIG. 2 is a diagram showing an example of the structure of a conventional separated optical head. l...Optical disk medium, Co...Motor, 3...Optical head, Hiro・°・Semiconductor laser,! ...Coupling lens, 6...Prism beam splitter, 7...
//lA wave plate,? ...Optical path conversion mirror, R...Condensing lens, IO...Photodetector, l/...Thermal fluctuation,
12... Optical path, /3... Separate optical head fixing part, /
≠...Separated optical head movable part, /j...Pipe type thermal fluctuation suppressing member, /1...Cut, /7 (aJ,
(b)...Laser exit window, /♂(aJ...guide,
/lrΦdoor...carriage, lri...pedestal, 20...
- Removable thermal fluctuation suppressing member, 2/(aha (b7...
・Band-shaped plate, 22Ca), Φ...Data signal, 2
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Claims (3)

[Claims] (1) In a separate optical head, in which a fixed part consisting of an optical system such as a light source and a movable part consisting of a light beam drive mechanism are separated, and the two parts are connected by spatial propagation of the light beam, the fixed part and the movable part are separated. An optical head characterized in that a thermal fluctuation suppressing member is arranged along the optical path between the movable parts. (2) The optical head according to claim 1, wherein the thermal fluctuation suppressing member is made of a flexible member that can be expanded and contracted. (3) The optical head according to claim 1, wherein the thermal fluctuation suppressing member is composed of two band-shaped plates.