JPH03192537A - optical head device - Google Patents

Abstract

PURPOSE:To prevent dust from entering the optical head device by providing an opening other than an opening corresponding to an objective lens in an optical head holding member or a cover for it and arranging a filter therein. CONSTITUTION:The optical head holding member 4 has the opening 36 other than the opening 21 corresponding to the objective lens 6 in the cover and the filter 33 whose air resistance is as small as possible is fitted in the opening 36. Further, transparent glass 31 for dust protection is fitted in an optical window 16. Consequently, an flow of air shown by an arrow 34 is generated by negative pressure with the rotation of a discoid recording medium 17. At this time, when the flow rate from the opening 36 is large, an air flow with large fluid resistance which passes through bearing holes 14 and 15 is suppressed substantially. Therefore, all of outside air passes through the filter 33 to prevent dust from entering the cover 13.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical head device applied to magneto-optical or optical information recording and reproducing devices.

(Prior Art) This type of optical head device employs an objective lens to irradiate the surface of a disk-shaped recording medium with a Radhe beam reduced to a diameter of about 1 μm. A folding mirror is used to refract the light into an optical path that guides the light ray from the semiconductor radar as a light source. For example, as shown in FIGS. 3 and 4, the optical head device includes an objective lens 6, an objective lens holding member L that holds the objective lens 6t, and a disk-shaped recording medium 170. In order to correct the positional deviation caused by the eccentricity of the recording medium 17, an adjusting means for slightly moving the objective lens 6 in the optical axis direction of the objective lens and in the tracking direction, and an adjustment means for adjusting the objective lens 6, the light source and An optical head holding member (carriage) 4 is equipped with an optical system that connects the sensors with an optical path. The adjusting means includes a focusing coil 8 and a tracking coil 9 provided on the outer periphery of the objective lens holding member 1, and a permanent magnet 10a, a lob, and an electromagnetic yoke l1m provided on the optical head holding member 4 side opposite thereto.

In addition to the folding mirror 12, the optical system includes a beam splitter, a condenser lens, a photodetector, and a semiconductor laser (all not shown). In this conventional example, the objective lens 6 and the folding mirror 12 are placed on a fixed base separate from the optical head holding member 4, and are connected to the folding mirror 12 through the optical path window 16. ing. A cover 13 having an opening 21 formed at a location corresponding to the objective lens 6 is attached to the optical head holding member 4, and includes an optical path window 22 between the objective lens 6 and the folding mirror 12. The upper space of the optical head holding member 4 is covered.

Further, the optical head holding member 4 is formed with a sliding bearing hole 14.15 for moving the optical head holding member 4 in the tracking direction 19, and a guide rail (not shown) is inserted into the sliding bearing hole 14.15. It is.

(Problem to be Solved by the Invention) The problem here is that when the disk-shaped recording medium 17 rotates in the direction of the arrow 18 for recording and reproduction, a negative pressure is generated against the opening 21 that sucks out air. That's true. For this purpose, via the optical path window 16 or the bearing hole 14.15
to the inside of the optical head holding member 4, and further to the optical path window 2.
External air flows into the cover 13 through the cover 13, and at this time, it carries in dust. This adheres to each optical element in the optical system path, and in particular, if it adheres to the surface of the folding mirror 12 or the objective lens 60, it affects the amount of light directed to the recording medium during recording and reproduction, and the amount of light reflected from there. This will prevent correct writing and reading.

(Object of the Invention) The present invention has been made based on the above circumstances, and the negative pressure generated by the rotation of the recording medium in the aperture corresponding to the objective lens is actively pumped into the optical head holding member or into its cover. The present invention attempts to provide an optical head device that allows air to flow through a filter, suppresses the introduction of air from other sources, and avoids the intrusion of dust.

(Means for Solving the Problems) For this reason, the present invention provides an objective lens, an objective lens holding member that holds the objective lens, an adjusting means for finely moving the holding member in the optical axis direction of the objective lens and in the tracking direction, and the objective lens. In an optical head device in which an optical head holding member includes at least a part of an optical system that connects a lens, a light source, and a sensor through an optical path, the optical head holding member communicates with the objective lens through an opening facing the objective lens or The cover for this is configured to communicate through another opening, and a filter with low air resistance is disposed in the latter opening KFi, so that air flows from the outside to the inside through the filter. are doing.

(Function) Conventionally, air was introduced through the bearing hole, but now air is flowing through the opening, and air introduction without a filter is essentially avoided, and air is flowing through the bearing hole. Therefore, the intrusion of dust can be prevented, and staining of the objective lens surface, folding mirror surface, etc. can be avoided.

Therefore, highly reliable recording and reproduction can be maintained.

(Example) Hereinafter, an example of the present invention will be specifically described based on FIG. 1. In addition, here, the same reference numerals are shown on the drawings for the same constituent members as in the conventional example, and the explanation thereof is omitted. In particular, the part according to the present invention is that the cover 13 of the optical head holding member 4 is provided with an aperture 36 that is different from the aperture 21 corresponding to the objective lens 6. A small filter 33 is attached to the. In addition, the optical path window 16 is provided with a transparent glass 31 for dustproofing.
is embedded. Therefore, an air flow as shown by an arrow 34 is generated due to the negative pressure caused by the rotation of the disk-shaped recording medium 17. At this time, if the air flow rate from the opening 36 is large, the airflow with large flow resistance passing through the bearing hole 14.15 will be substantially suppressed, and therefore all external air will need to pass through the filter 33. 13, and also prevents dust from entering the optical head holding member 4, such as the folding mirror 12, and more effectively prevents air from entering from the bearing holes 14 and 15. For this purpose, blocking walls 31 and 32 may be provided in the optical head holding member 4 at a position away from the optical path.

In another embodiment shown in FIG. 2, another opening 41 is formed in line with the optical path window 16, and a filter 43 is attached thereto. Further, as in the previous embodiment, a transparent glass 31 is fitted into the optical path window 16. Therefore arrow 4
Air circulation such as 0.42 is made, and the filter 43
Air flows only through the optical head holding member 4 or into the cover 13, thereby preventing dust from entering.

Note that in the above embodiment, only a part of the optical system is installed in the optical head holding member 4, and the other part is a separated optical system placed on the fixed base (not shown), but all the optical systems The present invention can also be applied to an optical head device having a structure in which the system is installed inside the optical head holding member 4.

(Effects of the Invention) As described in detail above, the present invention provides an aperture separate from the aperture corresponding to the objective lens in the optical head holding member or the cover thereof, and a filter is provided in this aperture. By allowing air to circulate inside through the media, the intrusion of dust can be substantially prevented and recording and playback can be achieved with high reliability.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing one embodiment of the present invention, FIG. 2 is a perspective view showing another embodiment, and FIGS. 3 and 4 are perspective views of a conventional example. 6... Objective lens, 4... Optical head holding member, 1
2... Reflection mirror 14.15... Bearing hole, 17
...Recording medium, 21...Aperture, 16...Optical path window,
31...Transparent glass, 36.41-...Opening, 33.
43...Filter×゛ Fig. 1 ( Fig. 2 Fig. 4

Claims (1)

[Claims] An objective lens, an objective lens holding member that holds the objective lens, an adjusting means for slightly moving the holding member in the optical axis direction of the objective lens and in the tracking direction, and an optical system that connects the objective lens, the light source, and the sensor with an optical path. In an optical head device in which at least a portion of the objective lens is provided in an optical head holding member, the optical head holding member communicates with the objective lens through an opening facing the objective lens, or a cover for the optical head holding member communicates with the objective lens through another opening. and a filter with low air resistance is disposed in the latter opening so that air flows from the outside to the inside through the filter.