JPH0240139A - Objective lens driving device - Google Patents

Abstract

PURPOSE:To smoothly displace an objective lens in a focusing direction by using a flexible printed board as a means to supply a current to a driving coil, and drawing it out in a tracking direction between an intermediate supporting body and a movable supporting board. CONSTITUTION:In an objective lens driving device in which an objective lens holding member 2 is supported on the intermediate supporting body 5 with a focusing flat spring member 3 and also, the intermediate supporting body 5 is supported on the movable board 6 with a tracking flat spring member, the flexible printed board 10 to supply the current to the driving coil 7 which displaces the objective lens holding member 2 is used. And it is connected adhesively on the objective lens holding member 2, the focusing flat spring member 3, the intermediate supporting body 5, and the movable supporting board 6, and is set so as to be drawn out in the tracking direction by conforming its width direction to the focusing direction between the intermediate supporting body 5 and the movable supporting board 6. In such a way, it is possible to displace the objective lens smoothly in the focusing direction.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an objective lens that displaces an objective lens in order to perform focus control and tracking control in an optical head that irradiates a laser beam onto an optical recording medium such as an optical disk. This relates to a drive device.

[Conventional technology]

In optical information recording and reproducing devices, the focus of the light beam is focused along the optical axis of the objective lens so that the light beam emitted from the objective lens is accurately focused on a track formed on the recording medium. In order to accurately track the optical beam onto the trunk of the recording medium, it is essential to perform focus control to displace the optical beam in the direction of the recording medium, and tracking control to displace the optical beam in the tracking direction perpendicular to the track direction and the focus direction so as to accurately track the optical beam onto the trunk of the recording medium.

Generally, in order to perform such control, the objective lens is held in an objective lens holding member, supported so that it can be freely displaced with respect to the base, and a driving force is applied to displace it in the focusing direction and the tracking direction. Take the drive coil that is generated and insert the drive coil into the magnetic circuit provided on the base.

The objective lens can be displaced by the driving force generated by supplying current to the driving coil.

Conventionally, the means for supporting the objective lens so that it can be freely displaced with respect to the base is to rotate it around an axis to displace it in the tracking direction, and to slide it along the axis to move it in the focus direction. A fulcrum shaft method in which the object is displaced, and a molded hinge method in which the object is displaced in the tracking direction or focus direction through a molded hinge formed by resin molding to have a hinge part that can swing in two orthogonal directions have been used. .

However, these methods have drawbacks such as the inability to accurately displace the objective lens in the focusing direction or the tracking direction in some cases, and poor productivity due to the complicated structure. proposed a means for supporting an objective lens with a leaf spring member and allowing the objective lens to be freely displaced by its elasticity.

For example, as shown in FIG. 4, such means includes focus plate spring members 3, 3, which are long in the direction perpendicular to the tracking direction and the focus direction, on the top and bottom surfaces of the objective lens holding member 2 that holds the objective lens 1. One end side is fixed, and the other end side of the focus plate spring members 3 is supported by an intermediate support 5. On the other hand, one end side of the tracking plate spring members 4, 4 is fixed to both side surfaces of the intermediate support body 5 in the tracking direction, and the other end side thereof is fixed to a movable support stand 6, 6 erected on a base (not shown). has been done.

Further, a focus drive coil 7 is wound around the objective lens holding member 2, and ranking drive coils 1 to 8 are attached thereon. To supply current to these drive coils, four thin conductor wires 12 are passed through a hole 5a provided approximately in the center of the intermediate support 5, and one end of each is connected to the current supply stand 11. Current is supplied from the current supply source to the drive coil by connecting the other end side to the focus drive coil 7 and the tracking drive coils 8, 8 through the connection part 13 provided on the upper surface of the objective lens holding member 2. This is done by forming a path.

When the focus drive coil 7 is energized, the objective lens 1 supported in this way is displaced along the focus direction by bending the focus plate spring members 3 with the intermediate support 5 as a fulcrum, and tracking is performed. When the drive coils 8, 8 are energized, the tracking plate spring members 4, 4 are deflected using the movable supports 6, 6 as fulcrums, thereby being displaced in the tracking direction.

[Problem to be solved by the invention]

However, in the conventional objective lens driving device described above, the thin conductor wires 12 are used as means for supplying current to the drive coil, so during assembly, the thin conductor wires 12...
There are problems with workability, such as difficulty in soldering when connecting the wire to the drive coil and current supply stand 11, and wire breakage due to bending of the thin conductor wire 12. was.

Therefore, the above disadvantages can be eliminated by using a flexible printed circuit board with multiple wiring patterns formed on a base film instead of the thin conductor wire 12 as a means for supplying current to the drive coil, but the In order to supply current to the coil, it is necessary to pull out this flexible printed circuit board from the objective lens holding member 2. At this time, depending on how the flexible printed circuit board is pulled out, it may be pulled by force in the thickness direction.
The focus plate spring members 3, 3 and the tracking plate spring members 4 may be twisted due to the force in the width direction.
4 and the intermediate support 5, and thus the displacement of the objective lens 1, could be hindered.

[Means to solve the problem]

In order to solve the above-mentioned problem, an objective lens driving device according to the present invention uses a focus plate spring so that an objective lens holding member to which an objective lens is attached is displaced in a focus direction along the optical axis direction of the objective lens. The intermediate support is supported on the movable support base by a tracking plate spring member so as to displace the objective lens holding member in a tracking direction perpendicular to the focus direction and the track direction of the recording medium. In the supported objective lens drive device, a flexible printed circuit board that supplies current to a drive coil that displaces the objective lens holding member includes an objective lens holding member, a focus plate spring member, an intermediate support, and a movable support base. and between the intermediate support and the movable support,
The intermediate support is characterized in that it is pulled out in one tracking direction with its width direction aligned with the focus direction so as not to interfere with the movement of the intermediate support in the tracking direction.

[For production]

With the above configuration, since a flexible printed circuit board is used as a means for supplying current to the drive coil, the flexible printed circuit board is not prone to bending and breaking unlike thin wire wiring. Further, the soldering work is facilitated by simply connecting the current supply side and the drive coil side to both ends of the conductor pattern formed on the flexible printed circuit board. Furthermore, the flexible printed circuit board allows wiring to be grouped together, making wiring work easier. In this way, productivity can be improved by improving workability during assembly.

The flexible printed circuit board has sufficient flexibility, so even if it is attached to the focus plate spring member, it can smoothly displace the objective lens in the focus direction without impairing the elasticity of the focus plate spring member. can.

Additionally, the space between the intermediate support and the movable support is pulled out in the tracking direction so as not to impede the movement of the intermediate support in the tracking direction, so the objective lens can be smoothly displaced in the focus direction. .

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

Note that members having the same functions as those in the conventional example are denoted by the same reference numerals, and their explanations will be omitted.

As shown in FIG. 1, the objective lens driving device in this embodiment includes an objective lens 1 and an objective lens holding member 2 that holds the objective lens.
, the focus leaf spring members 3, 3, the tracking leaf spring members 4, 4, the intermediate support 5, and the movable support base 6.

The objective lens 1 is fixedly held around its periphery by an objective lens holding member 2. The optical axis direction of the objective lens 1 is the focus direction, and the direction perpendicular to the focus direction and the track direction of the recording medium (not shown) is the tracking direction. The objective lens holding member 2 has a focus drive coil 7 wound around its side surface, and has two focus drive coils 7 wound on one side surface in a direction perpendicular to the focusing direction and the tracking direction.
Two tracking drive coils 8 are arranged side by side.

On the top and bottom surfaces of the objective lens holding member 2 facing the side surfaces on which the tracking drive coils 8, 8 are provided, one end side of the focus leaf spring members 3, 3 is long in the direction orthogonal to the focusing direction and the tracking direction, respectively. The other ends of the focus plate spring members 3 are fixed to the intermediate support 5. This intermediate support 5
, one end side of the tracking leaf spring members 4, 4 is fixed to both side surfaces in the tracking direction, and the other end side of the tracking leaf spring members 4, 4 is two movable support stands 6, 6, which are erected on a base (not shown). are fixed respectively. In this way, the objective lens holding member 2, the focus plate spring member 3
-3. The tracking plate spring members 4, 4 and the intermediate support 5 are supported by the movable supports 6, 6, and can be displaced in the focusing direction and the tracking direction. Further, a magnet 9 is provided on the base at a distance from the tracking drive coils 8, 8, so that magnetic force acts on the focus drive coil 7 and the tracking drive coils 8, 8.

A flexible printed circuit board 10 is used as a means for supplying drive current to the focus drive coils 7 and 1 to the racking drive coils 8. This flexible printed circuit board 10 has a conductor pattern formed on a base film with a thickness of about 70 μm, and has sufficient flexibility. The flexible printed circuit board 10 is attached to the upper surface of the objective lens holding member 2 except for the objective lens 1, and is attached to the end of the conductor pattern at the coil end connecting portion 10a...
There are four locations. Further, the flexible printed circuit board 10 is then adhered onto the focus plate spring member 3 whose one end side is fixed to the upper surface of the objective lens holding member 2, and the fixed end of the focus plate spring member 3 on the intermediate support body 5. It is bent along the surface of the intermediate support 5 parallel to the focusing direction and the tracking direction, and is affixed along the surface parallel to the focusing direction and the tracking direction, and the direction is changed toward the tracking direction from approximately the center of this side surface. The tip of the intermediate support 5 is arranged so that when the intermediate support 5 moves in the tracking direction, an unreasonable force does not occur and hinder this movement.
It is pulled out into space with its width direction aligned with the focus direction, and the end portion having the current supply section 10b is attached to the movable support base 6.

In the above configuration, when a current is supplied to the focus drive coil 7, a drive force in the focus direction is generated by the electromagnetic force generated in the focus drive coil 7 and the magnetic force of the magnet 9, and this drive force is applied to the objective lens holding member. It acts on 2. As shown in FIG. 2, the objective lens 1 is displaced in the focus direction as the focus plate spring members 3 are bent with the intermediate support 5 as a fulcrum. Also,
When a current is supplied to the tracking drive coils 8, 8, as shown in FIG. When the tracking plate spring members 4 are bent, they are displaced in the tracking direction.

In this embodiment, the flexible printed circuit board 10 is attached to the upper surface of the objective lens holding member 2 and the focus plate spring member 3 supporting this surface. It may also be attached to the bottom surface of the focus plate spring member 3 supporting this surface.

〔Effect of the invention〕

As described above, the objective lens driving device according to the present invention is provided with intermediate support by the focus plate spring member so that the objective lens holding member to which the objective lens is attached is displaced in the focus direction along the optical axis direction of the objective lens. The intermediate support is supported by a tracking plate spring member on a movable support base so as to be supported by the body and to displace the objective lens holding member in a tracking direction perpendicular to a focus direction and a track direction of the recording medium. In the objective lens drive device, a flexible printed circuit board that supplies current to a drive coil that displaces the objective lens holding member is attached to the objective lens holding member, the focus plate spring member, the intermediate support, and the movable support base. and is drawn out in the tracking direction between the intermediate support and the movable support with the width direction of the intermediate support consistent with the focus direction so as not to impede the movement of the intermediate support in the tracking direction. be.

As a result, since a flexible printed circuit board is used as a means for supplying current to the drive coil that drives the objective lens in the focusing direction and the tracking direction, there is no possibility of bending and disconnection during assembly, which is the case with thin wire wiring. Instead, it can make soldering work and wiring work easier, and productivity can be improved.

Furthermore, since the flexible printed circuit board has sufficient flexibility, even if it is attached to the focus plate spring member, the objective lens can be smoothly displaced in the focus direction without impairing the elasticity of the focus plate spring member. Can be done. Between the intermediate support and the movable support, the intermediate support is pulled out in the tracking direction so as not to interfere with the movement of the intermediate support in the tracking direction, allowing the objective lens to be smoothly displaced in the focus direction. It also produces effects.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the present invention, in which FIG. 1 is a perspective view showing the configuration of an objective lens driving device, and FIG. 2 shows a state in which the objective lens is displaced in the focus direction. The side view shown in FIG. 3 is a plan view showing a state in which the objective lens is displaced in the tracking direction. FIG. 4 is a perspective view showing the configuration of a conventional objective lens driving device. 1 is an objective lens, 2 is an objective lens holding member, 3 is a focus leaf spring member, 4 is a tracking leaf spring member, 5 is an intermediate support, 6 is a movable support base, 7 is a focus drive coil, 8 is a tracking drive coil, 10 is a flexible printed circuit board. ■ Figures 1 to 5 Figure 2 Figure 4

Claims (1)

[Scope of Claims] 1. An objective lens holding member to which an objective lens is attached is supported by an intermediate support member by a focus plate spring member so as to be displaced in a focus direction along the optical axis direction of the objective lens, and In the objective lens drive device, the intermediate support is supported by a tracking leaf spring member on a movable support base so as to displace the objective lens holding member in a tracking direction perpendicular to a focus direction and a track direction of a recording medium. A flexible printed circuit board that supplies current to a drive coil that displaces the objective lens holding member is attached to the objective lens holding member, the focus plate spring member, the intermediate support, and the movable support, and and the movable support base, the objective lens drive device is pulled out in the tracking direction with the width direction of the intermediate support consistent with the focus direction so as not to impede the movement of the intermediate support in the tracking direction. .