JPH0294127A - Object lens driving device - Google Patents

Abstract

PURPOSE:To improve the holding rigidity of an object lens holding body against external force in an arbitrary direction other than the tracking and focusing directions by supporting the holding body in a state where the holding body can be turned by means of the twist of plate springs in the direction perpendicular to the optical axis of an object lens. CONSTITUTION:Tracking control is performed by turning an object lens holding body 3 in the direction perpendicular to the optical axis 16 of an object lens 6 by means of the electromagnetic force produced by the electric current made to flow to a coil 12 for tracking and the magnetic field produced by a permanent magnet 13 and magnetic yoke 9. Focusing control is performed by moving the holding body 3 in the direction parallel to the optical axis 16 of the object lens 6 by means of the electromagnetic force produced by the electric current made to flow to a coil 11 for focusing and the magnetic field produced by the magnet 13 and yoke 9. Since the holding body 3 is supported in a turnable state by means of an intermediate member 2 through two plate springs 1a and 1b in such way, the rigidity of the holding body against external force in an arbitrary direction other than the tracking and focusing direction can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an objective lens driving device, and more particularly to an objective lens driving device in an optical recording/reproducing device such as an optical disk device.

BACKGROUND OF THE INVENTION In recent years, objective lens driving devices have been used for optical recording, which irradiates the surface of an optical recording medium with a laser beam in a spot shape to record information on the recording medium and reproduce information recorded on the recording medium. The performance of playback devices has been frequently improved.

A conventional objective lens driving device will be described below with reference to the drawings. FIG. 6 is an exploded perspective view of a conventional objective lens driving device. FIG. 7 is a perspective view of the objective lens driving device.

In FIG. 6, 1 is a tracking plate spring, 2 is an intermediate member, 3 is an objective lens holder, 6 is an objective lens, 16 is an optical axis of the objective lens, and 17 is a holding member for the plate spring 1. A fixing surface 14 of the leaf spring 1 is fixed to a fixing surface 4 of the intermediate member 2 that is parallel to the optical axis 16 . Fixed surface 15 of leaf spring 1
is fixed to a fixed surface 5 that is parallel to the optical axis 16 of the objective lens holder 3 and includes the center of gravity of the objective lens holder 3. Therefore, the objective lens holder 3 is supported so as to be rotatable in a direction perpendicular to the optical axis 16 by the twisting of the leaf spring 1.

7 is a focusing leaf spring, and 9 is a magnetic yoke which also serves as a base support member. One end of the leaf spring 7 is fixed to a fixed surface 8 perpendicular to the optical axis 16 of the intermediate member 2. The other end of the leaf spring 7 is fixed to a fixed surface 10 of the magnetic yoke 9. Therefore, the objective lens holder 3 is supported so as to be able to translate in a direction parallel to the optical axis 16 by bending the leaf spring 7.

11 is a focusing coil, 12 is a tracking coil, and 13 is a permanent magnet. The focusing coil 11 is wound around the outer circumference of the objective lens holder 3, and the tracking coil 12 is fixed to the objective lens holder 3. The permanent magnet 13 is fixed to the magnetic yoke 9 so as to face the focusing coil 11 and the tracking coil 12.

Regarding the objective lens drive device configured as above,
The operation will be explained below.

FIG. 8 is a schematic diagram illustrating the tracking control of the objective lens driving device, in which FIG. 8(a) shows a state where the objective lens holder 3 is located at a neutral point, and FIG. 8(b) shows a state where the objective lens holder 3 is located at a neutral point. This shows a state in which the body 3 is under tracking control.

In tracking control, the objective lens holder 3 is rotated in a direction perpendicular to the optical axis 16 of the objective lens 6 using an electromagnetic force generated by a current flowing through the tracking coil 12 and a magnetic field generated by the permanent magnet 13 and the magnetic yoke 9. It is done by letting The displacement angle θ of the objective lens holder 3 shown in FIG. 8(b) is determined by the relative displacement distance between the objective lens 6 and the desired laser beam irradiation position on the information recording medium.

FIG. 9 is a schematic diagram illustrating the focus control of the objective lens driving device. FIG. 9(a) shows the state where the objective lens holder 3 is located at the neutral point, and FIG. 9(b) shows the state where the objective lens holder 3 is located at the neutral point. A state in which the lens holder 3 is under focus control is shown.

Focus control moves the objective lens holder 3 in a direction parallel to the optical axis 16 of the objective lens 6 using electromagnetic force generated by a current flowing through the focusing coil 11 and a magnetic field generated by the permanent magnet 13 and the magnetic yoke 9. It is done by Objective lens holder 3 shown in FIG. 9(b)
The displacement X is determined by the relative defocus distance between the objective lens 6 and the information recording medium in the optical axis 16 direction.

Problems to be Solved by the Invention However, in the conventional configuration described above, the objective lens holder is rotatably supported with respect to the intermediate member by the twisting of a single leaf spring, so that external force on the objective lens holder is There is a significant difference in the rigidity of the support member against external forces depending on the direction of the support member. In other words, among the external forces on the objective lens holder, the plate spring has high rigidity against external forces in the shearing direction, but there is a moment that causes the plate spring to bend in the first order, or a moment that causes the plate spring to bend in the second order. The problem was that its rigidity was low against external forces in the translational direction.

The present invention solves the above-mentioned problems, and aims to provide an objective lens drive device that realizes a support member that has high rigidity against external forces in arbitrary directions other than the tracking direction and the focus direction. .

Means for Solving the Problems In order to achieve the above object, the objective lens driving device of the present invention includes an objective lens holder holding an objective lens, an objective lens holder that passes through the center of gravity of the objective lens holder, The objective lens holder is rotatably supported with a line substantially parallel to the optical axis of the lens as the rotation axis.It has a configuration consisting of two leaf springs arranged in series and substantially perpendicular to each other in the direction of the rotation axis. ing.

Operation The objective lens driving device of the present invention operates by twisting two leaf springs that are arranged in series and at substantially right angles to each other in the rotational axis direction that passes through the center of gravity of the objective lens and is substantially parallel to the optical axis of the objective lens. By supporting the objective lens holder so that it can rotate in a direction perpendicular to the optical axis of the objective lens, high rigidity support is achieved against external forces on the objective lens holder in any direction other than the tracking direction and the focusing direction. are doing.

Example Below, regarding an example of the objective lens driving device of the present invention,
This will be explained with reference to the drawings. FIG. 1 is an exploded perspective view of an objective lens driving device in an embodiment of the present invention. FIG. 2 is an exploded perspective view showing the fixing positions of the two plate springs in FIG. 1 to the intermediate member. FIG. 3 is a perspective view of the objective lens driving device.

In Fig. 1, Ia and lb are tracking plate blades,
2 is an intermediate member, 3 is an objective lens holder, 6 is an objective lens, 16 is an optical axis of the objective lens, and 17 is a pressing member for the leaf springs la and lb. The objective lens holder 3 has a plate spring la
, lb, so as to be rotatable in a direction perpendicular to the optical axis 16.

7 is a focusing leaf spring, and 9 is a magnetic yoke which also serves as a base support member. One end of the leaf spring 7 is fixed to a fixed surface 8 perpendicular to the optical axis 16 of the intermediate member 2. The other end of the leaf spring 7 is fixed to a fixed surface 10 of the magnetic yoke 9. Therefore, the objective lens holder 3 is supported so as to be able to translate in a direction parallel to the optical axis 16 by bending the leaf spring 7.

11 is a focusing coil, 12 is a tracking coil, and 13 is a permanent magnet. The focusing coil 11 is wound around the outer circumference of the objective lens holder 3, and the tracking coil 12 is fixed to the objective lens holder 3. The permanent magnet 13 is fixed to the magnetic yoke 9 so as to face the focusing coil 11 and the tracking coil 12.

Regarding the objective lens drive device configured as above,
The operation will be explained below.

FIG. 4 is a schematic diagram illustrating tracking control of the objective lens driving device, in which FIG. 4(a) shows a state in which the objective lens holder 3 is located at the neutral point, and FIG. A state in which the holder 3 is under tracking control is shown.

In tracking control, the objective lens holder 3 is rotated in a direction perpendicular to the optical axis 16 of the objective lens 6 using an electromagnetic force generated by a current flowing through the tracking coil 12 and a magnetic field generated by the permanent magnet 13 and the magnetic yoke 9. It is done by letting The displacement angle θ of the objective lens holder 3 shown in FIG. 3(b) is determined by the relative displacement distance between the objective lens 6 and the desired laser beam irradiation position on the information recording medium.

FIG. 5 is a schematic diagram illustrating the focus control of the objective lens driving device. FIG. 5(a) shows the state where the objective lens holder 3 is located at the neutral point, and FIG. 5(1)) shows the state where the objective lens holder 3 is located at the neutral point. A state in which the objective lens holder 3 is under focus control is shown.

Focus control moves the objective lens holder 3 in a direction parallel to the optical axis 16 of the objective lens 6 using electromagnetic force generated by a current flowing through the focusing coil 11 and a magnetic field generated by the permanent magnet 13 and the magnetic yoke 9. It is done by Objective lens holder 3 shown in FIG. 5(b)
The displacement X is determined by the relative defocus distance between the objective lens 6 and the information recording medium in the optical axis 16 direction.

As described above, according to this embodiment, the objective lens holder is
Since it is rotatably supported by the intermediate member via two leaf springs, high rigidity support against external forces in any direction other than the tracking direction and the focusing direction to the objective lens holder is realized.

Effects of the Invention As described above, the present invention supports the objective lens holder so as to be rotatable in a direction perpendicular to the optical axis of the objective lens by twisting two leaf springs, thereby adjusting the tracking direction to the objective lens holder. , and an excellent objective lens driving device that can provide high rigidity support against external forces in any direction other than the focus direction.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of an objective lens drive device according to an embodiment of the present invention, FIG. 2 is an exploded perspective view showing the fixing positions of two leaf springs to an intermediate member, and FIG. 3 is an exploded perspective view of the objective lens drive device in an embodiment of the present invention. FIG. 4 is a schematic diagram illustrating tracking control of the objective lens driving device, FIG. 5 is a schematic diagram illustrating focus control of the objective lens driving device, and FIG. 6 is a conventional objective lens driving device. FIG. 7 is a perspective view of a conventional objective lens drive device, FIG. 8 is a schematic diagram illustrating tracking control of the conventional objective lens drive device,
FIG. 9 is a schematic diagram illustrating focus control of a conventional objective lens driving device. la, lb...Tracking leaf spring, 2...
...Intermediate member, 3...Objective lens holder,
6... Objective lens, 7... Focus plate blade, 9... Magnetic yoke, 11...
- Focusing coil, 12... Tracking coil, 13... Permanent magnet. Name of agent: Patent attorney Shigetaka Awano (1 person)

Claims (1)

[Claims] The objective lens holder holds an objective lens, and the objective lens holder is rotated about a line that passes through the center of gravity of the objective lens holder and is approximately parallel to the optical axis of the objective lens as a rotation axis. first and second plate-shaped elastic support members arranged in series in the direction of the rotational axis and substantially perpendicular to each other, and the first and second plate-shaped elastic support members are rotated. an intermediate member that holds the objective lens holder in the axial direction; a third elastic support member that supports the objective lens holder movably in the optical axis direction via the intermediate member; a base support member that supports the objective lens holder via a second plate-shaped elastic support member, the intermediate member, and the third elastic support member; The first and second plate-shaped elastic support members each include a driving means and a second driving means for driving the objective lens in a direction perpendicular to the optical axis direction, and each of the first and second plate-shaped elastic support members has a branch line formed by an extended surface of the other. An objective lens driving device characterized in that it substantially coincides with a rotation axis.