JPH04278228A - Optical disk device - Google Patents

Abstract

PURPOSE:To make small the size of a movable section of an optical head and enhance seek response and accuracy. CONSTITUTION:A carriage 10 is clamped between a magnetic circuit which comprises an outer yoke 2, a permanent magnet 2, an inner yoke 4 and a junction yoke 5. The carriage 10 is supported by the inner yoke 4 and is driven by a seek coil 13 which runs through the inner yoke 4, thereby performing seek operation. The play between the carriage 10 and the inner yoke 4 is adjusted by an adjusting screw 17.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device having a separate head driven by a voice coil linear motor.

0002

2. Description of the Related Art Some optical disk devices that achieve faster seek operations by reducing the weight of the movable part use a separate head in which the optical head is divided into a movable part and a fixed part. Furthermore,
Some separation type heads share a focus magnetic circuit and a seek magnetic circuit of an actuator in order to reduce the weight of the movable part.

[0003] In such a shared magnetic circuit, an outer yoke, a permanent magnet, and an inner yoke are installed parallel and symmetrical in the radial direction of the optical disk, and the movable parts include a carriage with a seek coil and an actuator with an objective lens. are arranged one behind the other and connected by parallel leaf springs. Then, there are two parts inside the seek coil and the annular structure of the actuator.
The inner yoke of the book is inserted into the carriage, which is supported via bearings on support shafts parallel to the inner and outer yokes.A linear motor consisting of a seek coil and a magnetic circuit drives an actuator back and forth, and the actuator moves the objective lens up and down. It is designed to be driven by

0004

[Problems to be Solved by the Invention] However, in the conventional example described above, in order to increase the thrust of the linear motor, it is necessary to widen the width of the inner yoke, and the existence of the support shaft becomes an obstacle, so it is difficult to reduce the thickness. This makes it difficult to improve the responsiveness of the carriage.

An object of the present invention is to provide a thin optical disk device with good carriage acceleration performance and focus frequency characteristics of a separation type head.

[0006]

[Means for Solving the Problems] An optical disk device according to the present invention for achieving the above-mentioned object is an optical disk device using a separated head, in which a cross section of a magnetic circuit of a voice coil type linear motor that drives a carriage is provided. The two square inner yokes are also used as sliding shafts of the carriage, and an adjustment screw is provided for adjusting the gap between the carriage and the inner yokes.

[0007]

[Operation] The optical disc device having the above configuration does not require a support shaft for the carriage, so the carriage can be made smaller.
In addition, the driving force is large and the seek response is improved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail based on the illustrated embodiments.

FIG. 1 shows a plan view of the main part, and FIG. 2 shows a plan view of the main part.
3 is a sectional view taken along line BB, and FIG. 4 is a sectional view taken along line CC. A symmetrical magnetic circuit is fixed on the base 1, and a movable part is supported so as to be movable in the front-rear direction. In the magnetic circuit, permanent magnets 3, 3 are attached to the inner surfaces of two long outer yokes 2, 2 in the front and back, respectively, and inner yokes 4, 4 are attached to the inside of the permanent magnets 3, 3 in parallel with the outer yokes 2, 2. The outer yokes 2, 2 and the inner yokes 4, 4 are connected at the front and rear ends by relay yokes 5, 5 separately on the left and right sides. The distance between the left and right inner yokes 4, 4 is maintained at a constant interval by a circular spacer 6 having a light passage hole 6a inscribed on the front end side and a circular spacer 7 inscribed on the rear end side. 2 are leaf springs 8, 8 interposed between the base 1 and the base 1;
These magnetic circuits are biased toward the center by a total of four screws 9, and are fixed to the base 1 by a total of four screws 9.

The movable parts include a part attached to the carriage 10 which is movable only in the front and rear directions with respect to the base 1, a part attached to the actuator 11 which is movable up and down, and two upper and lower plates connecting these parts. The wing-shaped parts 10a, 10a provided vertically at the front and rear ends of the carriage 10 sandwich the inner yoke 4 from above and below, so that it is supported by the inner yoke 4 so as to be movable back and forth. The carriage 10 has a protrusion 10b between the upper and lower wing-shaped parts 10a, and the protrusion 10b abuts against the inner surface of the inner yoke 4 to regulate the left and right position. A seek coil 13 is installed near the center of the carriage 10 and wound between the inner yoke 4 and the permanent magnet 3. This seek coil 13 and a magnetic circuit fixed to the base 1 cause the voice coil to A type of linear motor is configured.

Parallel leaf springs 12, 12, which have one end fixed to the front end of the carriage 10, pass above and below the seek coil 13 and support the actuator 11 behind the seek coil 13 in a vertically movable manner. The actuator 11 is formed in an annular shape passing between the inner yoke 4 and the permanent magnet 3, and an objective lens 14 is fitted in the upper part thereof, and focus coils 15 are fixed to the left and right sides, one above and below the other. A light passage hole 10c in the front and back direction is formed in the center of the carriage 10, a diagonally upward mirror 16 is fixed directly below the objective lens 14 at the rear end, and the front end is opened toward the light passage hole 6a of the spacer 6. ing.

In addition, in order to regulate the vertical position with high precision, as shown in the cross-sectional view of FIG.
, 10a, the adjusting screws 17, 17 are screwed together, and the adjusting screw 1
The tip of the adjusting screw 17 faces the lower surface of the inner yoke 4, and the vertical play with the inner yoke 4 can be adjusted by adjusting the position of the tip of the adjusting screw 17.

Furthermore, as shown in FIG. 6, if a spring 18 is sandwiched between the head of the adjusting screw 17 and the wing-shaped portion 10a, it is possible to prevent the positional accuracy from decreasing due to play of the adjusting screw 17 itself. Can be done. The tip of the adjustment screw 17 and the inner yoke 4
Since the adjustment screws 17 slide against each other and cause friction, it is desirable to use synthetic resin as the material for the adjustment screws 17, but it is also effective to embed a small piece of fluororesin 19 at the tip of the adjustment screws 17 as shown in FIG.

FIG. 8 shows an embodiment in which a sliding plate 20 in the form of a leaf spring is sandwiched in the carriage 10 between the adjustment screw 17 and the lower surface of the inner yoke 4. Friction can be reduced, and the influence of play of the adjusting screw 17 can also be reduced due to the elasticity of the sliding plate 20.

FIG. 9 is a perspective view of the optical disc device, showing an example of the arrangement of the optical head section and spindle motor 30 within the base 1. As shown in FIG. A prism 32 including a dichroic mirror is fixed in front of the laser light source 31, and a mirror 33 is placed in front of the prism 32, and the mirror 33 is located on the center line of the light passage hole 10c of the carriage 10. prism 3
A condensing lens 34 and a mirror 35 are installed in the reflection direction on the mirror 33 side of No. 2, and a light splitting prism 36 and a sensor 37 are installed in the reflection direction of the mirror 35.

Here, the laser light emitted from the laser light source 31 passes through the light passage hole 10c of the carriage 10 via the prism 32 and the mirror 33, is reflected by the mirror 16, is focused by the objective lens 14, and is directed to the spindle motor 30.
The light is reflected by the lower surface of an optical disk (not shown) that is rotationally driven by the radiator. The reflected light returns to the prism 32 along the same optical path,
It is reflected, passes through a condensing lens 34, is reflected by a mirror 35, is divided into three optical paths by a light splitting prism 36, and is sent to a sensor 37.
incident on . The carriage 10 is driven by a linear motor to perform tracking by moving in the radial direction of the optical disk, and by controlling the current flowing through the focus coil 15, focusing is performed to adjust the vertical position of the objective lens 14.

In the above configuration, since the inner yoke 4 also serves as the sliding shaft of the carriage 10, the width of the carriage 10 can be made smaller than before, and the inner yoke 4 and the optical member of the fixed part of the optical head can be The mounting surface to the base 1 becomes the same surface, making it possible to manufacture with higher precision.

[0018]

As explained above, the optical disc device according to the present invention does not require a dedicated support shaft for the carriage, so the carriage can be made smaller, and the gap between the carriage and the inner yoke can be adjusted. The seek response and focus frequency characteristics of the device are improved and the device becomes thinner.

[Brief explanation of the drawing]

FIG. 1 is a plan view of main parts.

FIG. 2 is a sectional view taken along line AA in FIG. 1;

FIG. 3 is a sectional view taken along line BB in FIG. 1;

FIG. 4 is a sectional view taken along line CC in FIG. 1;

FIG. 5 is a sectional view taken along line DD in FIG. 1;

FIG. 6 is a sectional view of a first modification.

FIG. 7 is a sectional view of a second modification.

FIG. 8 is a sectional view of a third modification.

FIG. 9 is a perspective view of the optical disc device.

[Explanation of symbols]

1 Base 2 Outer yoke 3. Permanent magnet 4 Inner yoke 10 Carriage 11 Actuator 14 Objective lens 17 Adjustment screw 18 Spring 19 Sliding piece 20 Sliding plate

Claims (6)

[Claims] 1. An optical disk device using a separate head, in which two inner yokes with a square cross section constituting a magnetic circuit of a voice coil type linear motor that drives a carriage are also used as sliding shafts of the carriage, and the carriage is connected to the carriage. An optical disc device characterized in that an adjustment screw is provided for adjusting the gap between the inner yokes. 2. The optical disc device according to claim 1, wherein a tip of the adjusting screw directly contacts the yoke. 3. The optical disc device according to claim 1, further comprising an elastic body disposed between the head of the adjusting screw and the carriage so as to generate a repulsive force in a direction opposite to the direction of movement of the adjusting screw. 4. The optical disc device according to claim 2, wherein a small piece made of a material having a small coefficient of friction is embedded in the tip of the adjusting screw. 5. The optical disc device according to claim 1, wherein the adjusting screw is made of a synthetic resin material. 6. The optical disc device according to claim 1, further comprising a sliding plate disposed between the adjusting screw and the yoke.