JPH01204231A - Compact optical disk device - Google Patents

Abstract

PURPOSE:To cause a system compact and to easily assemble a head into a driving enclosure by fitting all of a fixed part, a movable part and a linear motor, which moves the movable part, to a case with the same rigidity and fitting the whole case to the driving enclosure. CONSTITUTION:The movable part of a magneto-optical head equips an actuator 14, an objective lens 15, a spring up mirror 16, a bearing 23 and a VCM coil 21 and the movable part is fixed to a movable part case 25. Then, the other parts are fit to a fixed part case 26. A slide shaft 22 is fit to the fixed part case 26 and a fixed part case 24 is made by an aluminum die-cast, etc., and united with a sub-frame 27. Thus, the movable part goes to light and the linear motor can be made compact. When the head is fit to the driving enclosure, it can be comparatively easily assembled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of an optical head in a write-once or rewritable optical disc device.

[Prior Art] Conventionally, the most standard optical recording head uses optical components such as a laser oscillator, collimator, prism, lens, and beam splitter, an objective lens, and a microscopic optical recording head that moves the objective lens around the circumference and in the focal direction. It consists of an access machine (hereinafter referred to as an actuator) for moving the mold, etc., but all of these are housed in a rigid case, and in order to move it to the target truck, the whole case is moved by a near motor etc. . This is called an integrated head.

FIG. 2 is a diagram schematically showing an example of a conventional Kerr type magneto-optical head. 11 is a laser diode, 12 is a collimator lens, and 13 is a polarizing beam splitter 51.
4 is an actuator, 15 is an objective lens, 16 is a flip-up mirror, 17 is a focus error detector, and 18 is a 1/
2 wavelength plate, 19 and 20 are magneto-optical signal detectors, 21 is VC
M coil, 22 is a slide shaft, 23 is a bearing, and 24 is a fixing member for fixing the slide shaft to the frame.

All the parts that make up the optical recording head are fixedly attached to a case 25 made of aluminum or the like, and are slid by the magnetic field of permanent magnets (not shown) placed across the coil 21 and the electromagnetic force generated by the coil current. Move along the axis.

On the other hand, there are separate heads designed to reduce access time, and some of these have been put into practical use. There are various ways to do this, but in short, the head is separated into a fixed part and a movable part, and the fixed part is fixedly housed in the body of the drive, while only the light part, including the objective lens, moves. ing.

FIG. 3 schematically shows a conventional separation type head.

The movable part includes an actuator 14, an objective lens 15, a flip-up mirror 16, a bearing 23, and a VCM coil 21, which are fixed to a movable part case 25. The other parts are attached to the fixed part case 26. Note that the flip-up mirror 16 is hidden below the objective lens 15.

In this case, as in the example shown in FIG. 2, the slide shaft 22 is directly attached to the drive frame (not shown because it is too large) using a fixing member 24.

In this example, since the mass of the moving parts is small, the same access time can be achieved with a small linear motor.

Alternatively, the same linear motor allows for faster access times.

[Problems and Objectives to be Solved by the Invention] The conventionally used integrated head has a heavy head unit;
In order to move this at high speed, a near motor that generates a large amount of force is required.

A larger output also requires a larger voice coil, which also increases the number of moving parts.

All of these lead to an increase in the size of the system and impede miniaturization of the drive.

Regarding the separate type head, the fixed part and the movable part of the head (in fact, the slide shaft that supports it) are each independently fixed to the drive frame.

As is well known, the light beam used for reading and writing must be accurately incident on the disk, and the alignment of the fixed part of the head and the sliding shaft of the movable part with respect to the body must be performed very precisely. However, it is very difficult to correctly position and install the slide shaft on the body made of aluminum ram etc., which is why such separate heads are only used in large and expensive high-end models. It becomes.

[Means for Solving the Problem] The present invention solves the problem by attaching all of the fixed part, the movable part, and the linear motor for moving the movable part to one rigid case, and by attaching the whole case to the drive body. This eliminates the drawbacks of the embodiments.

[Embodiment] FIG. 1 shows an embodiment of the magneto-optical head according to the present invention, in which the movable part includes an actuator 14, an objective lens 15, a flip-up mirror 16, a bearing 23, and a VCM coil 21. is fixed to the movable part case 25. The other parts are attached to the fixed part case 26.

A crucial difference between the embodiment shown in FIG. 3 and this embodiment of the invention is that in this case the slide shaft 22 is attached to a fixed part case 26. That is, the fixed part case 26 is made of aluminum die-casting or the like, and is integrated with the subframe 27. Reference numeral 28 is a hole used when fixing the subframe 27 to the main frame (not shown because it is large) with screws. Note that if the main shaft motor for rotating the disk is mounted on the present substrate frame, the subframe must be made large and heavy due to its weight, which is contrary to the spirit of the present invention, so this is not done.

[Effects of the Invention] Conventionally, the method described here has not been used for disks with a diameter of 130 mm to 120 mm because of the difference in radius between the outermost and innermost peripheries (i.e., the objective lens must be driven). Stroke) is large, fixed part,
A case housing all of the movable parts and the linear motor that drives the movable parts becomes large, which not only makes assembly and installation difficult, but also makes it difficult to obtain the rigidity of the case. On the other hand, for small-diameter discs with a diameter of 100 mm or less, the stroke of the objective lens only needs to be about 15-20 mm, so the size is not much different from the movable part of a conventional integrated head. And then everything subsides.

Using such a head has the advantage that the linear motor can be made smaller because the moving parts are lighter.In addition, since the most delicate adjustments are made within this subframe, the accuracy during manufacturing and adjustment is reduced. is likely to occur, and
When attaching the head to the drive unit, the position and inclination can be adjusted using a simple adjustment mechanism, so it can be assembled relatively easily.

In this case, it is desirable that the permanent magnet for driving the voice coil be arranged separately from the head, but it is also possible to arrange it on the subframe according to the present invention.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a magneto-optical head according to the present invention. FIG. 2 is a diagram schematically showing an example of a conventional Kerr type magneto-optical head. FIG. 3 is a diagram schematically showing a conventional separation type head. 11 Laser diode 12 Collimator lens 13 Polarizing beam splitter 14 Actuator 15 Objective lens 16 Lifting mirror 17 Focus error detector 18
1/2 wavelength plates 19 and 20 Magneto-optical signal detector 21 VCM coil 22 Slide shaft 23 Bearing 24 Fixing member 25 for fixing the slide shaft to the frame Movable part case 26 Fixed part case 27 Sub-frame 28 Connect the sub-frame to the main frame Diagram 63 of the holes used when fixing with screws to

Claims (1)

[Claims] In a writable optical disc device in which the outer diameter of the disc is 100 mm or less, the portion of the optical head that performs recording and/or reproduction that includes a laser oscillator and a photodetector is
At least the objective lens and actuator are mounted on a subframe that is fixedly attached to the optical drive.
A small optical disk device, characterized in that it moves along a slide shaft fixed to a subframe fixedly attached to the optical drive by a moving means.