JPS63119026A - Optical system driving device - Google Patents

Abstract

PURPOSE:To eliminate the generation of the twist of a plate spring and to prevent the axis falling of an optical system light axis by using the plate spring deforming to the bellows shape for a supporting means to support a moving optical type. CONSTITUTION:At the side part of both sides of a supporting stand 34 one edge of plate springs 36a and 36b constituted of an elastic body is tightly fixed and a notch is provided at the plate springs 36a and 36b. Other edge of the plate springs 36a and 36b is respectively tightly fixed at the side part facing to an intermediate member 38 constituted of a rigid body, one edge of plate springs 40a and 40b constituted of the elastic body respectively is tightly fixed at the upper surface part and lower surface part of an intermediate member 38, and other edge of the plate springs 40a and 40b is respectively tightly fixed at the upper surface part and the lower surface part of an objective lens holding body 44 having an objective lens 42. The plate springs 36a and 36b, when the objective lens holding body 44 is driven in a tracking direction (x axis direction), is deformed to the bellows shape in the surface shape of a plane.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical system drive device that is suitably used, for example, to drive an objective lens of an optical head in an optical information recording/reproducing device.

[Prior Art] Conventionally, there has been an optical type in which a laser beam is irradiated onto the surface of an information recording medium in a spot shape to record information on the recording medium and/or to reproduce information recorded on the recording medium. Information recording and playback! It2F has been put into practical use.

An example of such *i is an optical disk device. The optical disc, which is a recording medium on which information is reproduced by this optical disc device, has a width of about 1 to 2 m and a length of 1 to 2 m.
An information track consisting of a row of information pits of about 37 Lm is formed in a spiral shape or a concentric circle shape. When reproducing the information recorded as the information pit string, the optical head irradiates the information track of the optical disk with a laser beam in the form of a minute spot while rotating the optical disk, and the beam spot scans the information pit data. . When a photodetector detects the reflected light or transmitted light of the light irradiated onto the optical disk surface in this way, the optical difference of the light incident on the photodetector depends on whether or not there is an information pit at the beam spot position. Character changes. In this way, a reproduced signal corresponding to the information pit string can be obtained.

In addition, in such an optical disk device, it is extremely important that the minute spot always accurately scan the information pit row on the recording medium. For this purpose, autofocusing is required to correct the focus shift caused by the warping of the recording medium, and autotracking is required to correct the irradiation position shift due to the eccentricity of the recording medium. As a method to realize this auto-focusing function and auto-tracking am note,
An objective lens driving device as shown in FIG. 4 has been conventionally considered. 4 is a perspective view showing a conventional objective lens drive device, and FIGS. 5A and 5B are perspective views showing a deformed state of a leaf spring in the objective lens drive device.

As shown in FIG. 4, the conventional objective lens driving device 2 has a rectangular base 4. As shown in FIG. A U-shaped support 6 is fixed to the corner of the base. One ends of leaf springs 8a and 8b made of elastic bodies are fixed to both sides of the support base. #The other ends of the leaf springs 8a and 8b are respectively fixed to opposing sides of an intermediate member IO made of a rigid body. Further, on the upper and lower surfaces of the intermediate member 10, leaf springs 12a are respectively formed of elastic bodies.

One end of L2b is fixed. The plate spring 12a.

The other ends of 12b are fixed to the upper and lower surfaces of an objective lens holder 16 having an objective lens 14, respectively. The objective lens 14 is attached to the outer periphery of the side surface of the objective lens holder 16 in the focusing direction (y-axis direction) as shown in the figure.
Focusing T to drive to! ! A moving coil 1
B is provided.

Furthermore, four tracking drive coils 20 are fixed on the outer periphery of the focusing drive coil 1.8. The tracking drive coil is provided to drive the objective lens 14 in the X-axis direction. Further, a magnetic circuit (however, one is omitted in Figure 1) constituted by a permanent magnet 22 and a yoke 24 is provided at a position facing the coils 18 and 20 in two axial directions. There is.

1 configured as above! At tll, coil 18
．． By applying a current to 20, each leaf spring 8a, 8b and 12a is activated by electromagnetic force with a magnetic circuit consisting of a permanent magnet 22 and a yoke 24.

12b is elastically deformed and can drive the objective lens 14 in the tracking direction and the focusing direction.

In the above-mentioned apparatus, when driving the objective lens 14 in the tracking direction (X-axis direction), the 511th (a
), when equal forces F+ and Fz (FI=Fz) act on the leaf springs 8a and 8b in the X-axis direction, the leaf springs 8a and 8b move in the tracking direction (X-axis direction) without twisting or the like. Deforms elastically. At this time, as shown in Figure 5 (
As shown in b), different forces F3. When force F4 (Fff>F4) is applied, the side on which force F is applied undergoes greater elastic deformation and twisting occurs around the Z-axis, causing the optical axis A of the objective lens 14 to shift from the tracking direction (X-axis direction). It shifts.

These include the coil 18.20 and the objective lens holder 16.
Moment force may be generated due to mismatch between the center of gravity of the movable part consisting of the object lens 14, etc., and the point of action of the electromagnetic force generated by the permanent magnet 22, yoke 24, and coil 18, 20, or the movable member may move in the focusing direction (y-axis direction). ) is caused by the generation of moment force, etc.

[Problem to be solved by the invention 1 As stated above, is it possible to drive an optical system in which the optical system is supported by a plate spring made of an elastic body? At the i position, the optical axis of the optical system may be tilted due to twisting of this leaf spring. Furthermore, there is a problem in that the servo control becomes unstable due to the twisting of the leaf spring.

Conventionally, countermeasures have been taken to deal with such problems, such as increasing the thickness of the leaf spring to make it difficult to cause twisting.

However, if the thickness of the leaf spring is increased, twisting becomes less likely to occur, but the natural frequency increases and the DC sensitivity decreases. ! iI have some problems.

Furthermore, increasing the length of the leaf spring in order to solve this problem has the problem of hindering miniaturization of the device.

[Purpose] The present invention was made in view of the problems of the prior art described above, and its purpose is to prevent the optical axis of the optical system from collapsing;
It is an object of the present invention to provide an optical system driving device that is capable of stably driving an optical system, is small in size, and has high sensitivity.

[Means for Solving the Problems] According to the present invention, the above object is an optical system drive device in which a moving optical system is supported by a leaf spring; When the optical system moves in the direction of movement.

This is achieved by an optical system driving device that is characterized by deforming into a bellows shape in a plane including the length direction in which the optical system moves and the length direction of the leaf spring.

[Function] By using the above means, the effective length of the spring can be increased even if the length is the same as the actual length of a conventional leaf spring, and the length of the leaf spring can be increased without increasing the natural frequency of the leaf spring. The thickness of the spring can be increased. Furthermore, since the thickness of the leaf spring can be increased, it is possible to prevent the optical axis of the optical system from tilting.

[Example] Hereinafter, an example according to the present invention will be described specifically and in detail based on the drawings.

Note that this embodiment will be explained using an objective lens as an example of the optical system.

FIG. 1 is an exploded perspective view showing an embodiment of an optical system driving device according to the present invention.

As shown in the figure, the optical system driving device 30 according to the present invention has a rectangular base 32. The base is connected and fixed to, for example, an optical head section of an optical information recording/reproducing apparatus by appropriate means. A support stand 34 having a U-shape is fixed to a corner of the base stand 32. As shown in FIG. One ends of leaf springs 36a and 36b made of elastic bodies are fixed to both side portions of the support base 34. The leaf springs 36a, 36b are provided with notches as shown. This is leaf spring 3
This is to transform 6a and 36b into a bellows shape.

The other ends of the leaf springs 36a and 36b are fixed to opposing sides of an intermediate member 3B made of a rigid body. Further, one ends of leaf springs 40a and 40b made of elastic bodies are fixed to the upper and lower surfaces of the intermediate member 38, respectively. The other ends of the leaf springs 40a and 40b are fixed to the upper and lower surfaces of an objective lens holder 44 having an objective lens 42, respectively.

Further, as shown in the figure, a focusing drive coil 46 for driving the objective lens 42 in the focusing direction (y-axis direction) is provided on the outer circumference of the side surface of the objective lens holder 44. Furthermore, the focusing drive coil 4
Four tracking drive coils 48 are fixed on the outer periphery of 6. The tracking drive coil 48 is provided to drive the objective lens 42 in the X-axis direction.

Further, a magnetic circuit (one of which is omitted in the figure) constituted by a permanent magnet 50 and a yoke 52 is provided at a position facing the coils 46 and 48 in two axial directions. There is.

In the device configured as above, the coil 46.48
By applying a current to each leaf spring 36, each leaf spring 36 is
a, 36b and 40a.

40b is elastically deformed and can drive the objective lens 42 in the tracking direction and the focusing direction.

The optical system drive device according to the present invention is configured as described above, and the plate springs 36a and 36b are prevented from being twisted by using plate springs that deform into a bellows shape.

Hereinafter, the leaf spring that deforms into a bellows shape will be described in more detail.

FIG. 2 is a plan view showing a deformed state of the leaf spring in the optical system driving device according to the present invention.

As shown in FIG. 2, the leaf springs 36a and 36b deform into a bellows shape in the plane shown in the figure when the objective lens holder 44 is driven in the tracking direction (X-axis direction). This is achieved by providing the leaf springs 36a, 36b with notches 60 as shown in FIG. 3(a). Incidentally, FIGS. 3(a) and 3(b) are front views showing the shape of the cut in the leaf spring. The notch provided in the leaf spring is formed in a plane perpendicular to the moving direction of the objective lens holder 44. As a result, the effective length of the leaf spring can be increased without increasing the size of the optical system driving device, so that the natural frequency can be lowered even if the leaf spring is made thicker. This also prevents the leaf spring from being twisted.

The above embodiment is an example in which a plate spring deformed into a bellows shape is used as a support means in the tracking direction of the optical system, but this is useful as a support means in the focusing direction, and supports at least one of the tracking direction and the focusing direction. It may be used as a supporting means in other directions, not limited to tracking and focusing.

Further, in the above embodiment, the shape of the leaf spring was such that a notch 60 was made as shown in FIG. 3(a), but this may also be a notch 62 in the shape as shown in FIG. The present invention can be applied to any shape of leaf spring as long as it can be deformed into a bellows shape.

Furthermore, although this embodiment is an example in which the present invention is applied to an optical system drive device of an optical information recording and reproducing device, it is of course applicable to other optical devices such as a shape detection device and a laser processing machine.

[Effects of the Invention J As specifically explained in detail above, the present invention is an optical system drive device that uses a plate spring that deforms into a bellows shape as a support means for supporting a moving optical system. It is possible to eliminate the occurrence of twisting of the spring, thereby eliminating the tilting of the optical axis of the optical system. In addition, the optical system part g that can drive the optical system stably and is compact and highly sensitive! h
equipment can be provided.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of an optical system driving device according to the present invention, FIG. 2 is a plan view showing a deformed state of a leaf spring, and FIG.
Figures (a) and (b) are front views showing the notch shape of the leaf spring, and Figure 4 is a perspective view showing a conventional objective lens drive device.
FIGS. 5(a) and 5(b) are perspective views showing the deformed state of the leaf spring in the objective lens driving device. 30 --- Optical system drive device 36a, 36b --- Leaf spring 42 --- Objective lens 44 --- Objective lens holder agent Patent attorney Seki Taira Yamashita Figure 3 Figure 4

Claims (1)

[Claims] (1) In an optical system driving device in which a moving optical system is supported by a leaf spring; An optical system driving device characterized by deforming into a bellows shape in a plane including the length direction in which the leaf spring moves and the length direction of the leaf spring.