JPH03198227A - Objective lens driver - Google Patents

Abstract

PURPOSE:To reduce the thickness and size of the device and to enable fast access operation by fixing a linear motor to a plane movable part and supporting an objective lens holder and a raised mirror at one end of the linear motor movable part. CONSTITUTION:The objective lens holder 2 is fixed to the movable part 4 by a support member and moves in parallel to the optical axis of an objective lens 1. The linear motor movable part 4 consists of a guide 8 and a bearing 9 and is supported movably in a radial direction of a disk. The movable part 4 is driven with the electromagnetic force generated by a fixed driving coil 5 and the magnetic circuit consisting of a magnetic yoke 6 and a permanent magnet 7. The movable part of the linear motor consists of the lens 1 and holder 2, raised mirror 3, movable part 4, and coil 5 and is nearly large enough only to hold the coil 5, so only necessary irreducible size is required and the device is made reducible in weight and size.

Description

[Detailed description of the invention] [Industrial application field] The present invention optically records information on a recording medium.

The present invention relates to an objective lens drive device in an optical disk device that performs reproduction and erasing.

[Conventional technology]

In an optical disk device that uses a laser beam as a light source and modulates the laser beam according to information to record it on a recording medium or read information that has already been recorded, the objective lens driving device is used to record information, During reproduction and erasing, focus control is performed to focus a light beam onto the surface of the recording medium to form a light spot, and tracking control is performed to make the light spot follow a certain recording track. Conventionally, these controls have been performed using an optical system. This was done by placing everything on the vehicle and roughly positioning the moving part of the near motor, and then performing precise positioning using an objective lens drive device that was mounted on the moving part of the linear motor and was movable in two directions: the focusing direction and the tracking direction. .

However, with this configuration, the load on the moving part of the linear motor increases, and the two-axis actuator on the moving part of the linear motor is susceptible to distortion and deformation during high acceleration. The disadvantage is that it is difficult to move from one recording track to another (hereinafter referred to as access operation) at high speed because precise positioning cannot be performed and recording or playback operations cannot be started until the vibrations subside. have.

On the other hand, 5PI performs high-speed access operations.
E Vol, 10780ptical Data St
orage Topical Meeting (1989
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” is known.

This optical disk device is shown in FIGS. 5 and 6.

FIG. 5 is a partially cutaway perspective view, and FIG. 6 is a sectional view.

According to this optical disk device, an optical system that generates a light beam is fixed to a device housing (not shown), and includes an objective lens 1 that focuses the light beam, an objective lens holder 2 that holds the objective lens, A lifting mirror 3 that guides the light beam to the objective lens 1 is mounted on the linear motor movable section 4 to reduce the weight of the movable section.
A high-speed access operation is performed using a voice coil motor with a strong driving force made up of a movable coil 5 provided in a movable part 4, and the objective lens holder 2 is driven in the focus direction by a focus drive coil 11 and a focus magnetic circuit I2. It is something.

[Problem to be solved by the invention]

However, in this configuration, since the magnetic circuit has a cross section as shown in FIG. 6, it becomes thick and large, and the voice coil motor must be placed outside the outer periphery of the disk 10, making the entire device large and heavy. There is.

SUMMARY OF THE INVENTION An object of the present invention is to provide an objective lens driving device for a small and thin optical disk device that can perform high-speed access operations while eliminating such conventional drawbacks.

[Means for Solving the Problems] The present invention provides an objective lens driving device that focuses a light beam onto the surface of a disk-shaped recording medium and positions it on a recording track, which includes a cavity parallel to the surface of the recording medium. a flat coil having a flat coil; a flat movable part holding the flat coil;
A linear motor having a magnetic circuit fixed to the device housing opposing this flat movable part, and a focus drive coil for driving the objective lens in the focus direction parallel to the optical axis are fixed, and the supporting member is fixed to the linear motor. an objective lens holder supported by the planar movable part of the linear motor via the linear motor; an objective lens drive means in the focus direction comprising the focus drive coil and a focus magnetic circuit fixed to the device housing; A rising mirror fixed to the flat movable part of the linear motor and guiding a light beam to the objective lens, the objective lens holder, and the raising mirror are fixed to any corner of the flat movable part of the linear motor. It is characterized by being supported.

[Example] An example of the present invention is shown in FIGS. 1, 2, and 3. Figure 1 is a partially cutaway perspective view, Figure 2 is a sectional view, and Figure 3 is a partially cutaway perspective view.
The figure is a front view.

In this objective lens drive device, a linear motor and a focus drive coil 11 for driving the objective lens 1 in a focus direction parallel to the optical axis are fixed, and the linear motor is supported by a flat movable part 4 of the linear motor via a support member. The objective lens holder 2 has an objective lens holder 2 , a focus magnetic circuit 12 fixed to the device housing, and a rising mirror 3 fixed to a movable part 4 of a linear motor and guiding a light beam to the objective lens 1 .

The linear motor has an air gap placed parallel to the recording medium surface of the disk 10, and includes a flat coil 5 held in a movable part 4, and a magnetic yoke fixed to a device housing opposite to each other with the movable part 4 in between. 6 and a magnetic circuit consisting of a permanent magnet 7.

Then, the objective lens holder 2 and the rising mirror 3 are
It is supported at the corner of the flat movable part 4 of the linear motor.

That is, this objective lens driving device directs a light beam generated from a fixed optical system (not shown) to the disk 10.
An objective lens holder 2 that holds an objective lens l that condenses light onto the medium surface, and a rising mirror 3 that guides a light beam to the objective lens 1 are fixed to one end of a movable part 40 of a linear motor. .

The objective lens holder 2 is fixed to the movable part 4 by a support member, and is movable in a direction parallel to the optical axis of the objective lens l.

Furthermore, the linear motor movable section 4 has a guide 8. The disk is movably supported in the radial direction by a linear support mechanism constituted by a hair ring 9, and is driven by electromagnetic force generated by a drive coil 5 fixed to the movable part 4 and a magnetic circuit consisting of a magnetic yoke 6 and a permanent magnet 7. be done.

The movable part of the linear motor is composed of an objective lens 1, an objective lens holder 2, a raising mirror 3, a movable part 4, a drive coil 5, and a hair ring 9.
Since it consists of only the size of the portion that holds the drive coil 5, it only needs to be of the minimum necessary size, and weight and size reduction can be achieved.

As shown in the cross-sectional view of FIG. 2, the two plate-shaped permanent magnets 7 magnetized in the thickness direction generate a magnetic field perpendicular to a plane parallel to the disk lO, and the magnetic poles of the generated magnetic field are They are arranged in opposite directions and form a magnetic circuit together with the magnetic yoke 6. The drive coil 5 is fixed to the movable part 4 so that the surface on which the coil is wound is parallel to the disk 10. With this configuration, the force constant of the linear motor is 6.58
[G/A] is obtained, and performance equivalent to the force constant of 6.5 [G/A] of the voice coil motor shown in FIG. 5 is achieved with a thin magnetic circuit.

As shown in the front view of FIG. 3, a light beam generated from a fixed optical system (not shown) is directed to an objective lens 1 by a rising mirror 3. As shown in the front view of FIG. The objective lens holder 2 is
It is driven in the focus direction by a focus drive coil 11 and a focus magnetic circuit 12.

FIG. 4 is a partially cutaway perspective view showing another embodiment of the present invention. The magnetic yoke 13 of the magnetic circuit of the linear motor is
As shown in the figure, a notch may be formed in the movable part of the objective lens 1, and the support mechanism for the movable part 4 of the linear motor may be included inside (effects of the invention). The linear motor according to the invention has a thin magnetic circuit while having the same performance as a conventional voice coil motor, and at the same time, the objective lens and raising mirror can be supported at one end of the linear motor movable part. The entire movable part and magnetic circuit can be placed under the disk, making it possible to make the optical disk device smaller and thinner.

Furthermore, since the linear motor movable section is attached with the objective lens and its holder, the erecting mirror, and the drive coil, it is lightweight and enables high-speed access operation.

Furthermore, since the linear motor movable section can be made to the minimum necessary size to hold the drive coil, the minimum resonance frequency can be increased, the servo band can be widened, and stable access operation can be realized.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an embodiment of the objective lens drive device of the present invention, FIG. 2 is a schematic sectional view of the linear motor and disk of the objective lens drive device of FIG. 1, and FIG. 4 is a perspective view of another embodiment of the objective lens drive device of the present invention. FIG. 5 is a perspective view of a conventional optical disk device. FIG. 6 is a perspective view of another embodiment of the objective lens drive device of the present invention.
FIG. 6 is a schematic cross-sectional view of the linear motor and disk of the optical disk device shown in FIG. 5; 1... Objective lens 2... Objective lens holder 3... Raising mirror 4... Moving part 5... Drive coil 6.13... Magnetism Yoke 7... Permanent magnet 8... Guide 9... Bearing 10... Disk 11... Focus drive coil 12... Focus magnetic circuit

Claims (1)

[Claims] (1) In an objective lens driving device that focuses a light beam on the surface of a disc-shaped recording medium and positions it on a recording track, the flat coil is arranged parallel to the surface of the recording medium and has a gap, and the flat coil a flat movable part that holds the
A linear motor having a magnetic circuit fixed to the device housing opposing this flat movable part, and a focus drive coil for driving the objective lens in the focus direction parallel to the optical axis are fixed, and the supporting member is fixed to the linear motor. an objective lens holder supported by the planar movable part of the linear motor via the linear motor; an objective lens drive means in the focus direction comprising the focus drive coil and a focus magnetic circuit fixed to the device housing; A rising mirror fixed to the flat movable part of the linear motor and guiding a light beam to the objective lens, the objective lens holder, and the raising mirror are fixed to any corner of the flat movable part of the linear motor. An objective lens driving device characterized in that it is supported.