JP2003109235A - Optical head device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical head device effectively absorbing even the vibration generated in the various directions although in the case the vibrating direction is always rotated. SOLUTION: The device is provided with an objective lens for recording information by converging light beams outgoing from a light source on an optical recording medium, a lens holder for holding the objective lens, a lens holder supporting member for supporting the lens holder movably in at least one direction out of the focusing direction or the tracking direction, and a driving part for making the lens holder move to at least one direction out of the focusing direction or the tracking direction with respect to the lens holder supporting member. In the lens holder supporting member, a buffer means 70 for absorbing the vibration furnished with a weight 72 is disposed, and the buffer means 70 is formed to a structural body having the sectional plane of secondary moment which is unchanged with respect to the direction of recording medium plane. The sectional plane of the weight 72 perpendicular to the focusing direction or parallel to the tracking direction is formed to be circular.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head device used for recording / reproducing an optical recording medium such as a compact disc (hereinafter referred to as "CD") or a digital versatile disc (hereinafter referred to as "DVD"). so,
In particular, it relates to the vibration absorbing structure.

[0002]

2. Description of the Related Art In an optical head device used for recording / reproducing an optical recording disk such as a CD or a DVD, which is an optical recording medium, a lens holder holding an objective lens is driven in a tracking direction and a focusing direction to make an optical recording disk. The signal is recorded / reproduced to / from. In such an optical head device, a lens holder that holds the objective lens, a lens holder support member that supports the lens holder so as to be driven in the tracking direction and the focusing direction of the objective lens, and a magnetic drive circuit that drives the lens holder are provided. Various optical parts are mounted on a common frame, and this frame is designed to move in the radial direction of the optical information disc when reproducing information from or recording information on the optical recording disc. The lens holder support member has a structure in which the lens holder is supported by a wire, and has a shaft sliding / rotating structure in which the lens holder is supported by a support shaft fitted in a shaft hole formed in the lens holder (hereinafter, referred to as this structure). There is a "sliding type"), whichever type is used, the lens holder, the lens holder supporting member and the magnetic drive circuit are connected by connecting the lens holder supporting member to the frame with screws or the like. It is mounted on the frame.

In such an optical head device, the vibration transmitted from the outside to the frame, for example, the vibration accompanying the rotational driving of the optical recording disk, is transmitted to the lens holder via the lens holder supporting member mounted on the frame. It may vibrate the objective lens. These vibrations
This may cause a failure of the focusing servo or the tracking servo, which hinders accurate recording / reproduction of information by the optical head device, which is not preferable.

In particular, the lens holder is slidably supported by the lens holder supporting member by the relationship between the shaft and the shaft hole into which the shaft is fitted, and is moved in at least one of the focusing direction and the tracking direction. In the so-called shaft-sliding optical head device that is configured, because of its structure, breakage in the servo surface is unlikely to occur due to vibration in the axial direction, but vibration in the direction orthogonal to the axis does not occur in the servo surface. Bankruptcy is likely to occur. The reason is that the clearance between the shaft and the bearing is small, so there is almost no allowance for vibration in the direction orthogonal to the shaft, that is, in the plane direction of the optical recording disk, and the servo breaks down due to the collision between the shaft and the bearing. , But temporarily, there is a risk of loss of control.

Therefore, by inserting a cushioning material between the lens holder supporting member and the frame, the vibration generated in the lens holder supporting member or the vibration which is transmitted from the frame to the lens holder supporting member is absorbed. Technology is proposed. The invention of Japanese Patent Application No. 2000-251739 filed by the present applicant is a further improvement of the vibration absorbing technique in the optical head device, and is not sandwiched between the lens holder supporting member and the frame. A damper means for absorbing vibration is provided at the position. The damper has an elliptical cross-sectional shape, and the vibration direction that can be absorbed can be adjusted by changing the major axis direction of the ellipse.

Further, in the shaft sliding type optical head device, a technique is known in which a damper is attached to a frame of the optical head device to absorb vibration. JP-A-10-31
The invention described in Japanese Patent No. 830 is one of them, and its outline is shown in FIG. In FIG. 4, reference numeral 90 indicates the main body of the optical head device. A damper 91 is attached to the side surface of the optical head device body 90. The damper 91 has a two-layer structure in which an elastic member 92 and a weight 93 are laminated and attached, and the elastic member 92 is attached to the side surface of the optical head device body 90. The damper 91 has a strip-shaped cross section, and the strip-shaped cross section is oriented in the vertical direction so as to absorb the vibration of the optical head device body 90 in the vertical direction.

[0007]

[Patent Document 1] Japanese Patent Application No. 2000-2
In the invention of 51739, since the cross-sectional shape of the damper is elliptical, damping effectively acts on the vibration of the ellipse in the major axis direction, but against the vibration of the elliptical minor axis. Has a drawback that the damping effect is low. Also,
In the case of the conventional example shown in FIG. 4, since the damper 91 is in the shape of a strip and the second moment of area varies depending on the direction, the damper 91 effectively acts on vibration in the vertical direction, but when the vibration direction fluctuates, it is absorbed. The frequency band of vibration that can be changed changes, and the damping effect is not stable.

Further, it is known that, when the engaging hole of the optical disk is eccentric, the vibration generated when the optical disk is mounted on the disk drive and rotationally driven rotates 360 degrees in a plane parallel to the optical disk. There is. Therefore, according to the above-mentioned conventional technique, it is difficult to effectively absorb the vibration that rotates 360 degrees.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and is against vibration in a direction orthogonal to the rotation center axis line, that is, in the plane direction of the optical recording medium, and An object of the present invention is to provide an optical head device capable of effectively absorbing the vibration direction even when the vibration direction is constantly rotating in the plane of the optical recording medium. The present invention also provides that the lens holder is slidably supported with respect to the lens holder support member by a relationship between a shaft and a shaft hole into which the shaft is fitted, and moves in at least one of a focusing direction and a tracking direction. An object of the present invention is to provide an optical head device capable of absorbing vibration particularly effectively in a shaft sliding type.

[0010]

The invention according to claim 1 is
An objective lens that collects light emitted from a light source on an optical recording medium to record information, a lens holder that holds the objective lens, and a lens holder that is movable in at least one of a focusing direction and a tracking direction. In an optical head device including a lens holder support member and a drive unit that moves the lens holder with respect to the lens holder support member in at least one of a focusing direction and a tracking direction, a weight is provided on the lens holder support member. Further, a shock absorbing shock absorbing means is provided, and the shock absorbing means is a structure in which the second moment of area is invariant with respect to the plane direction of the recording medium.

According to a second aspect of the present invention, in the first aspect of the invention, the weight has a circular cross section perpendicular to the focusing direction or parallel to the tracking direction.

According to a third aspect of the present invention, in the first aspect of the present invention, the lens holder supporting member is provided with a yoke provided with a driving portion, and supporting the yoke so as to be movable relative to the apparatus side. And a buffer member is disposed on the frame. The invention according to claim 4 is characterized in that, in the invention according to any one of claims 1 to 3, the weight has a cylindrical shape.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the lens holder slides on the lens holder support member depending on the relationship between the shaft and the shaft hole into which the shaft is fitted. It is movably supported and moves in at least one of a focusing direction and a tracking direction.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an optical head device according to the present invention will be described below with reference to the drawings.
In FIG. 2, the optical head device 1 is a CD or a DVD.
Information is recorded / reproduced on / from an optical recording disk 5 which is an optical recording medium such as, and an actuator 4 is arranged on a frame 2 made of a metal such as aluminum. The actuator 4 includes a lens holder 42 that holds the objective lens 41, and a lens holder support member 57 that supports the lens holder 42. The lens holder 42 includes the support shaft 5 that is erected on the lens holder support member 57.
It is mounted so as to be slidable along 0 and rotatable about the support shaft 50. When the lens holder 42 slides along the support shaft 50, the objective lens 41 moves in the focusing direction, and the light L emitted from the light source unit 11 is focused on the optical recording disk 5. Lens holder 42
Is rotated around the spindle 50, the objective lens 4
1 is the radial direction of the optical recording disk 5 (tracking direction)
To move to.

Between the lens holder support member 57 and the lens holder 42, an electromagnetic drive unit for driving the lens holder 42 in the focusing direction and the tracking direction with respect to the lens holder support member 57 is provided. . The drive unit includes a yoke provided on the lens holder support member 57 side, a drive magnet fixed to the yoke, and a drive coil wound around the lens holder 42. The drive magnets include focusing drive magnets 61 and 62 and tracking drive magnets 59 and 60. The drive coils include a focusing drive coil 47 and tracking drive coils 45 and 46.

The actuator 4 is mounted on the frame 2 and fixed by an appropriate means such as screwing. The frame 2 is attached to the main body of the disk drive device by a suitable guide means so as to be movable in parallel. The moving direction of the frame 2 is the radial direction of the optical recording disk 5 which is mounted on a disk drive device body (not shown) and is rotationally driven, and the objective lens 41 is moved in the radial direction of the optical recording disk 5 along with this movement. Then, the so-called seek operation is performed.

When the optical recording disk 5 is rotationally driven, vibration occurs in the plane direction of the optical recording disk 5 as described above. This vibration periodically moves over the entire circumference of the optical recording disk 5. In order to absorb the vibration that fluctuates periodically, in the embodiment according to the present invention, the shock absorbing cushioning means is arranged on the lens holder supporting member.

FIG. 1 shows an example of arrangement of the buffer means. As described with reference to FIG. 2, the lens holder support member 57 includes a yoke including the focusing drive magnets 61 and 62 and the tracking drive magnets 59 and 60, which form a drive unit, and an optical disk drive that supports the yoke. The frame 2 is provided so as to be movable relative to the device side. In the example shown in FIG.
A buffer means 70 is provided on the bottom surface of the frame 2 which constitutes a part of the lens holder support member 57.

As shown in FIGS. 1A and 1B, the cushioning means 70 includes an elastic member 71 made of chloroprene rubber or other rubber, and a weight 72 made of brass or the like attached to the elastic member 71. An elastic member 71 is attached to the bottom surface of the frame 2 with a two-layer structure made of. Therefore, the elastic member 71 portion functions as a cantilever. As shown in FIG. 1C, the buffer means 7
0 has a cylindrical shape as a whole. However, it suffices that at least the portion of the weight 72 has a cylindrical shape. Since at least the portion of the weight 72 has a cylindrical shape, the cushioning means 70 has a structure in which the second moment of area is unchanged with respect to the central axis of the cushioning means 70. In other words, since the cushioning means 70 is attached to the bottom surface of the frame 2 as described above, and is parallel to the plane of the optical recording disk, the second moment of area of the cushioning means 70 is equal to the plane direction of the optical recording disk. It has a circular structure that does not change. The second moment of area of the circular buffer means 70 is represented by πd̂4 / 64, where d is the diameter of the buffer means 70.

It is assumed that the rotational driving of the optical recording disk 5 shown in FIG. 2 causes vibrations over the range of 360 ° on this rotating surface. This vibration is horizontal vibration indicated by an arrow in FIG. 1A, and is vibration in the tracking direction.
The weight 71 of the buffer means 70 has a circular cross section parallel to the tracking direction or a cross section perpendicular to the focusing direction, and the second moment of area is constant with respect to the plane direction of the optical recording disk. Vibrations from any direction, and hence from any direction within the plane of rotation of the optical recording disk 5, can be absorbed by the damping means 70.

The main source of vibration of the optical disk drive device is the vibration due to the rotational drive of the optical recording disk 5 described above, and the vibration is caused by the bottom surface of the frame 2 as shown in FIG. 1 (a). By providing the cushioning means 70, the above-mentioned vibration can be absorbed, and the recording / reproduction accuracy can be improved by obtaining accurate force detection signal and tracking detection signal.

FIG. 3 shows an arrangement example of the buffer means 70. In FIG. 3, an elastic member 71 made of a rubber portion and a weight 72 made of brass are bonded to each other by adhesion to form a cushioning means 70. The cushioning means 70 has a cylindrical shape as a whole. The buffering means 70 is arranged on the bottom surface of the frame 2 of the optical head device by adhesion or the like.

When the optical head device is mounted on the optical disk drive device, the optical head device is affected by the vibration generated in the plane parallel to the surface of the optical recording disk as the optical recording disk is rotationally driven. The direction of this vibration periodically fluctuates within the range of 360 degrees as described above. According to the embodiment described so far, the buffer means 70 having the weight 72 made of a structure whose second moment of area is invariant with respect to the plane direction of the optical recording disk is the lens holder supporting member 5.
Since it is arranged in the frame 2 substantially integral with the optical recording medium 7, the vibrations are equally absorbed by the vibrations from any direction in the plane parallel to the plane of the optical recording disk. As a result, it is possible to obtain a good detection signal without causing disturbance noise on the focusing detection signal and the tracking detection signal.

The embodiment shown in FIG. 2 has a lens holder 42.
However, the shaft-sliding optical head device is slidably supported by the lens holder support member 57 by the relationship between the shaft 50 and the shaft hole into which the shaft 50 is fitted, and is movable in the focusing direction and the tracking direction. Is configured as. According to the shaft-sliding optical head device, the vibration generated outside has a small allowance for the vibration in the planar direction because of the small clearance between the shaft 50 and the shaft hole. Therefore, when vibration exceeding the clearance occurs, the shaft and the bearing collide with each other and the servo breaks down, resulting in a temporary loss of control. On the other hand, according to the above-described embodiment of the present invention, since the buffering means 70 made of a structure in which the second moment of area does not change in the plane direction of the optical recording disk is arranged in the frame 2, vibration is effective. And a precise focusing signal or tracking signal can be obtained.

The buffer means 70 may be disposed on the upper surface of the frame 2. If structurally possible, the buffer means 70 may be provided on the bottom surface or the top surface of the lens holder support member 57 instead of the bottom surface or the top surface of the frame 2. The elastic member 71 of the cushioning means 70 and the weight 72 may have a transverse cross-sectional shape such that the second moment of area does not change with respect to the central axis, and may have a donut shape or a cylindrical shape.

[0026]

According to the first aspect of the present invention, the lens holder support member is provided with a vibration absorbing cushioning means having a weight, and the cushioning means has an optical recording medium having a second moment of area. Since the structure is invariant with respect to the plane direction and invariant with respect to the central axis, vibrations from all directions in the cross section of the buffering means, that is, when the optical disc is mounted on the disc drive and rotationally driven Vibrations that rotate 360 degrees in a plane parallel to the optical disc are absorbed by the buffering means, and an accurate focusing signal or tracking signal can be obtained.

According to the second aspect of the invention, the weight of the cushioning means has a circular cross section perpendicular to the focusing direction or parallel to the tracking direction, and the second moment of area is constant with respect to the central axis. Since it is a structure, it is possible to obtain the same effect as that of the invention described in claim 1. According to the inventions of claims 3 and 4, the same effect as that of the invention of claim 1 can be obtained.

According to the fifth aspect of the present invention, in a so-called shaft sliding type optical head device having a small clearance between the shaft and the bearing, the lens holder supporting member of the shaft sliding type optical head device has a cross section 2 Since the buffering means, which is a structure in which the second moment is invariable with respect to the plane direction of the optical recording medium, is provided, the vibration in the plane direction of the optical recording medium can be effectively absorbed.

[Brief description of drawings]

FIG. 1A is a front view showing an outline of an optical head device according to the present invention, FIG. 1B is a front view of a buffering means, and FIG. 1C is a plan view of the buffering means.

FIG. 2 is an exploded perspective view showing an embodiment of an optical head device according to the present invention.

FIG. 3 is a process drawing showing an example of disposition of buffer means used in the present invention.

FIG. 4 is a front view schematically showing an example of a conventional optical head device.

[Explanation of symbols]

2 frames 70 Buffer means 71 Elastic member 72 weights

Claims (5)

[Claims] 1. An objective lens for condensing light emitted from a light source onto an optical recording medium to record information, a lens holder for holding the objective lens, and the lens holder in at least one of a focusing direction and a tracking direction. An optical head device comprising a lens holder support member that movably supports and a drive unit that moves the lens holder with respect to the lens holder support member in at least one of a focusing direction and a tracking direction. Is provided with a damping means for absorbing vibrations, and the damping means is a structure whose second moment of area is invariant with respect to the plane direction of the recording medium. . 2. The optical head device according to claim 1, wherein the weight has a circular cross section perpendicular to the focusing direction or parallel to the tracking direction. 3. The lens holder support member has a yoke provided with a drive section and a frame that supports the yoke and is movable relative to the apparatus side, and a buffer member is arranged in the frame. The optical head device according to claim 1, which is provided. 4. The weight has a cylindrical shape.
The optical head device according to any one of 1. 5. The lens holder is slidably supported by a lens holder support member by a relationship between a shaft and a shaft hole into which the shaft is fitted, and is movable in at least one of a focusing direction and a tracking direction. The optical head device according to any one of claims 1 to 4, characterized in that: