JP2002074711A - Optical head device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical head device which stably operates while the play of a lens holder is prevented when it rotates around the supporting axis. SOLUTION: In the optical head device 1, a lateral pressure is imparted to the lens holder 4 to bring the axis hole 41 into contact with a prescribed position (contact part 43) of the supporting axis 3. In addition, when the lens holder 4 is driven in the tracking direction, the magnetic torque T1, T2 generating between a tracking driving coil 53 and a tracking driving magnet 51, 52 is controlled so that the center axial line H goes through the contact part 43 with which the inner peripheral surface of the axis hole 41 comes into contact corresponding to the supporting axis 3. As a result, the lens holder 4 rotates, in a state in which the inner peripheral surface of the axis hole 41 is in contact with the prescribed position (contact part 43) in the circumferential direction of the supporting axis 3. Further, the center of gravity G of the lens holder 4 including an objective lens 10 is superimposed on the prescribed position (contact part 43) of the supporting axis 3 with which the inner peripheral surface of the axis hole 41 comes into contact.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact disc (CD) and a digital versatile disc (DVD).
The present invention relates to an optical head device used for reproducing an optical recording disk such as an optical recording medium. More specifically, the present invention relates to the structure of an optical head device.

[0002]

2. Description of the Related Art An optical head device used for reproducing an optical recording disk (optical recording medium) such as a CD or a DVD holds an objective lens and fits into a lens holder having a shaft hole and a shaft hole. 2. Description of the Related Art There is known a shaft sliding and rotating system including a frame having a support shaft and a magnetic drive circuit for driving a lens holder mounted on the frame in a focusing direction and a tracking direction.

In this type of optical head device, Japanese Patent Laid-Open No.
In the publication No. -301022, as shown in FIGS. 4A and 4B, by disposing a pair of tracking drive coils 53 on the opposite side of the support shaft 3 from the side where the objective lens 10 is located, An optical head device 100 in which the center of gravity G of the entire lens holder 4A is positioned on the center axis of the support shaft 3 is disclosed. According to such an optical head device 100, the counterweight (balance weight) is attached to the lens holder 4A.
Even if the lens holder 4A is not attached to the support shaft 3,
Weight balance.

In the optical head device 100 configured as described above, a magnetic drive circuit including the tracking drive coil 53 and a tracking magnet (not shown) facing the coil is rotated about the center axis of the support shaft 3. A driving force is applied to the lens holder 4A to rotate the lens holder 4A around the support shaft 3.

[0005]

However, in such an optical head device 100, the center of gravity G of the entire lens holder 4A is located on the center axis of the support shaft 3, and the magnetic drive circuit applies a voltage to the lens holder 4A. Since the center of the rotating drive force is also on the center axis of the support shaft 3, it is determined which position in the circumferential direction of the support shaft 3 the inner circumferential surface of the shaft hole 41 contacts when the lens holder 4A rotates. Absent. For this reason, when the lens holder 4A rotates, the lens holder 4
It is easy for rattling between the shaft hole 41 of A and the support shaft 3 to occur. When such rattling occurs, the optical head device 100
In this case, the operation becomes unstable because the seismic resistance decreases, which is not preferable.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an optical head device that prevents rattling of a lens holder when the lens holder rotates around a support shaft and that operates stably. It is in.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to the present invention, an objective lens for converging light emitted from a light source to an optical recording medium is held, and a lens having an axial hole formed therein. An optical head device comprising: a holder, a frame having a support shaft fitted into the shaft hole, and a magnetic drive circuit capable of driving at least the lens holder to rotate about the support shaft, wherein the lens holder includes the lens holder. The inner peripheral surface of the shaft hole comes into contact with a predetermined position in the circumferential direction on the outer peripheral surface of the support shaft due to the side pressure applied to the shaft. It is configured to apply a rotational driving force to the lens holder, the central axis passing through a predetermined position or a position to which the lateral pressure is applied when viewed from the support shaft with respect to the predetermined position. And it features.

In the present invention, in the lens holder, the inner peripheral surface of the shaft hole comes into contact with a predetermined position in the circumferential direction of the support shaft due to the side pressure, and the predetermined position of the support shaft or the support shaft is higher than the predetermined position. The magnetic drive circuit applies a rotational drive force to the lens holder through which the central axis passes through the position to which the side pressure is applied when viewed from above. For this reason, the lens holder rotates while the inner peripheral surface of the shaft hole is in contact with a predetermined position in the circumferential direction of the support shaft. Therefore, no rattling occurs between the shaft hole of the lens holder and the support shaft, so that the optical head device has improved earthquake resistance and operates stably.

[0009] In the present invention, the magnetic drive circuit is configured to apply a rotational drive force passing through a predetermined position of the support shaft with which the inner peripheral surface of the shaft hole comes into contact with a center axis to the lens holder. Is preferred. With this configuration,
When the lens holder rotates, no rotational moment that causes rattling is applied to the lens holder, so that rattling can be reliably prevented.

[0010] In the present invention, the side pressure is applied to the lens holder when the inner peripheral surface of the shaft hole overlaps a predetermined position of the support shaft, or when viewed from the support shaft from the predetermined position. It is preferable to have a center of gravity at the coming position. In particular, it is preferable that the lens holder has a center of gravity at a position overlapping a predetermined position of the support shaft with which the inner peripheral surface of the shaft hole contacts. With this configuration, the center of gravity of the lens holder and the central axis of the rotational driving force applied to the lens holder by the magnetic drive circuit coincide with each other, so that when the lens holder rotates, a rotational moment that causes rattling is generated. Does not cover the lens holder.

In the present invention, it is preferable that a predetermined position of the support shaft where an inner peripheral surface of the shaft hole is in contact is set on a side of the circumferential direction of the support shaft opposite to a side where the lens holder is located. . With this configuration, the center axis of the rotational driving force is located at a position opposite to the objective lens when viewed from the shaft hole, and therefore, a drive coil or the like may be disposed on the opposite side to the objective lens. Therefore, there is an advantage that the lens holder can be easily designed in terms of the layout surface of the lens holder and the balance of the center of gravity.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical head device according to the present invention will be described below with reference to the drawings. Note that, in any of the embodiments described below, the basic configuration is common to the conventional embodiment, and thus, common parts are denoted by the same reference numerals. Also,
Prior to the description of each embodiment, a configuration common to each embodiment will be described.

(Common Configuration) FIG. 1 is an exploded perspective view showing an optical head device to which the present invention is applied.

As shown in FIG. 1, an optical head device 1 of the present embodiment is for reproducing an optical recording disk (optical recording medium) such as a CD or a DVD, and converts a laser beam emitted from a light source into an optical beam. A lens holder 4 for holding an objective lens 10 to be converged on a recording disk;
And a frame 2 for holding

The frame 2 has a substantially rectangular bottom wall 20 and side walls 23 to 26 vertically rising from four sides of the bottom wall 20. Of these side walls 23 to 26, tracking drive magnets 51 and 52, which are polarized and magnetized in the circumferential direction, are bonded and fixed to the inner peripheral surfaces of the side walls 23 and 24 extending in parallel with each other.

From the bottom wall 20, a pair of inner walls 27, 28 extending parallel to the side walls 23, 24 to which the tracking drive magnets 51, 52 are attached are formed. On the inner peripheral surfaces of the inner walls 27 and 28, focusing driving magnets 61 and 6 for turning the monopolar magnetized surface inward are provided.
2 are adhesively fixed.

At the center of the bottom wall 20 sandwiched between the pair of inner walls 27 and 28, the support shaft 3 is fixed in an upright state. A lens holder 4 is held on the support shaft 3 so that the lens holder 4 can move up and down and rotate.

The lens holder 4 has a cylindrical receiving portion 44.
And a side surface portion 45 surrounding the bearing portion 44. A pair of openings 411 and 412 are provided between the bearing portion 44 and the side surface portion 45 on both sides of the bearing portion 44.
Are formed. Further, on the upper surface side of the lens holder 4, a lens mounting portion 42 that protrudes thinly outward is formed, on which the objective lens 10 is adhesively fixed.

In the lens holder 4, the bearing 4
The support shaft 3 erected from the bottom wall 20 of the frame 2 is inserted into a shaft hole 41 formed in the shaft 4. Therefore, the lens holder 4 is movable in the axial direction (vertical direction / focusing direction indicated by the arrow F) along the support shaft 3 and at the same time the circumferential direction of the support shaft 3 (direction indicated by the arrow T / tracking direction). It is also possible to rotate.

Also, a pair of openings 41 of the lens holder 4
A pair of inner walls 27, 28 erected from the bottom wall 20 of the frame 2 are inserted into the insides of the first and second frames 412, respectively. Therefore, the bearing 44 of the lens holder 4 is disposed between the focusing drive magnets 61 and 62 attached to the pair of inner walls 27 and 28.

A focusing drive coil 63 is wound around the bearing 44 of the lens holder 4. A focusing magnetic drive circuit that moves the lens holder 4 in the vertical direction (focusing direction) along the support shaft 3 is configured between the focusing drive coil 63 and the focusing drive magnets 61 and 62.

A pair of tracking drive coils 53 is attached to the outer peripheral surface of the outer peripheral side surface 45 of the lens holder 4 so as to face the tracking drive magnets 51 and 52. These tracking drive coils 53
And between the tracking drive magnets 51 and 52,
A tracking magnetic drive circuit for rotating the lens holder 4 around the support shaft 3 (tracking direction) is configured.

In the optical head device 1 configured as described above, the lateral pressure (indicated by an arrow M) of the lens holder 1 is generally applied so that the lens holder 4 contacts a predetermined position on the outer peripheral surface of the support shaft 3. It is a target. Such a side pressure M is obtained, for example, by disposing the magnetic piece 54 at a position facing the tracking drive magnets 51, 52, etc., and by using a magnetic attraction force or the like acting between the magnetic piece 54 and the tracking drive magnets 51, 52. Use and generate.

[First Embodiment] FIG. 2 shows an optical head device 1 to which the present invention is applied, an objective lens 10, a lens holder 4, a support shaft 3, tracking driving magnets 51,5.
FIG. 4 is a plan view schematically showing the positional relationship of No. 2;

As shown in FIG. 2, in the optical head device 1 of the present embodiment, the side pressure M described with reference to FIG. In the present embodiment, the side pressure M acts from the side opposite to the side where the objective lens 10 is located when viewed from the shaft hole 41 and the support shaft 3. For this reason, the inner peripheral surface of the shaft hole 41 of the lens holder 4 is in contact with the outer peripheral surface of the support shaft 3 at a position opposite to the side on which the objective lens 10 is located in the circumferential direction. 4 to be contacted.

In the optical head device 1 configured as described above, the tracking drive coil 53 and the tracking drive magnet 5 constituting the tracking magnetic drive circuit
1 and 52, the tracking drive coil 53 is disposed on the opposite side in the circumferential direction of the lens holder 4, but in the present embodiment, a pair of the tracking drive coil 5 is provided.
The line L connecting the magnetic center positions 3 does not pass through the center of the shaft hole 41 and the center of the support shaft 3, and the side to which the lateral pressure M is applied is viewed from the center (the side where the objective lens 10 is located). Is shifted to the opposite side) and passes through the contacted portion 43 where the inner peripheral surface of the shaft hole 41 is in contact with the support shaft 3.

Therefore, when the lens holder 4 is driven in the tracking direction in the magnetic drive circuit, the tracking drive coil 53 and the tracking drive magnet 51,
The magnetic rotational driving forces T1 and T2 generated during the period 52
The center axis H passes through the contacted portion 43 where the inner peripheral surface of the shaft hole 41 contacts the support shaft 3. For this reason, in this embodiment, the lens holder 4 rotates while the inner peripheral surface of the shaft hole 41 is in contact with a predetermined position (contacted portion 43) in the circumferential direction of the support shaft 3. Therefore, the shaft hole 41 of the lens holder 4
Since no rattling occurs between the optical head device 1 and the support shaft 3, the optical head device 1 has high seismic resistance and stable operation.

In this embodiment, since the center axis H of the rotational driving force passes through a predetermined position (contacted portion 43) of the support shaft 3 with which the inner peripheral surface of the shaft hole 41 contacts, the lens holder 4 rotates. At this time, no rotational moment causing rattling is applied to the lens holder 4 at all, so that rattling can be reliably prevented.

Further, in the present embodiment, the objective lens 10
The center of gravity G of the lens holder 4 including the above overlaps with a predetermined position (contacted portion 43) of the support shaft 3 with which the inner peripheral surface of the shaft hole 41 contacts. For this reason, when the lens holder 4 rotates, there is an advantage that a rotational moment that causes rattling is not reliably applied to the lens holder 4.

Further, in the present embodiment, a predetermined position (contacted portion 43) of the support shaft 3 with which the inner peripheral surface of the shaft hole 41 contacts.
Is on the side opposite to the side where the lens holder 10 is located in the circumferential direction of the support shaft 3. For this reason, when viewed from the shaft hole 41, the central axis H of the rotational driving force comes to a position on the opposite side to the objective lens 10, so that the drive coil 53 and the like are disposed on the opposite side with respect to the objective lens 10. Good. Therefore, there is an advantage that the lens holder 4 can be easily designed in terms of the layout surface of the lens holder 4 and the balance of the center of gravity.

Second Embodiment FIG. 3 shows an optical head device 1 according to a second embodiment of the present invention.
FIG. 4 is a plan view schematically showing the positional relationship among a reference numeral 0, a lens holder 4, a support shaft 3, and tracking drive magnets 51 and 52.

As shown in FIG. 3, also in the optical head device 1 of the present embodiment, the side pressure M described with reference to FIG. Also in the present embodiment, the side pressure M acts from the side opposite to the side where the objective lens 10 is located when viewed from the shaft hole 41 and the support shaft 3. For this reason, the inner peripheral surface of the shaft hole 41 of the lens holder 4 is in contact with the outer peripheral surface of the support shaft 3 at a position opposite to the side on which the objective lens 10 is located in the circumferential direction. 4 to be contacted.

In the optical head device 1 configured as described above, the tracking drive coil 53 and the tracking drive magnet 5 constituting the tracking magnetic drive circuit
1 and 52, the tracking drive coils 53 are arranged on the opposite sides in the circumferential direction of the lens holder 4, and both of the pair of tracking drive coils 53 are located at the center of the shaft hole 41 and the center of the support shaft 3. Not suitable for
That is, the lines L1 and L2 extending perpendicularly from the tracking drive coil 53 from the magnetic center position of the tracking drive coil 53 do not pass through the center of the shaft hole 41 and the center of the support shaft 3, and when viewed from these centers, the lateral pressure M It deviates in the direction to which the voltage is applied (the side opposite to the side where the objective lens 10 is located), and passes through the contacted portion 43 where the inner peripheral surface of the shaft hole 41 is in contact with the support shaft 3.

Therefore, when the lens holder 4 is driven in the tracking direction in the magnetic drive circuit, the tracking drive coil 53 and the tracking drive magnet 51,
The magnetic rotational driving forces T1 and T2 generated during the period 52
The center axis H passes through the contacted portion 43 where the inner peripheral surface of the shaft hole 41 contacts the support shaft 3. For this reason, in this embodiment, the lens holder 4 rotates while the inner peripheral surface of the shaft hole 41 is in contact with a predetermined position (contacted portion 43) in the circumferential direction of the support shaft 3. Therefore, the shaft hole 41 of the lens holder 4
Since no rattling occurs between the optical head device 1 and the support shaft 3, the optical head device 1 has high seismic resistance and stable operation.

In this embodiment, since the center axis H of the rotational driving force passes through a predetermined position (contacted portion 43) of the support shaft 3 with which the inner peripheral surface of the shaft hole 41 contacts, the lens holder 4 rotates. At this time, no rotational moment causing rattling is applied to the lens holder 4 at all, so that rattling can be reliably prevented.

Further, in the present embodiment, the objective lens 10
The center of gravity G of the lens holder 4 including the above overlaps with a predetermined position (contacted portion 43) of the support shaft 3 with which the inner peripheral surface of the shaft hole 41 contacts. For this reason, when the lens holder 4 rotates, there is an advantage that a rotational moment that causes rattling is not reliably applied to the lens holder 4.

Further, in this embodiment, a predetermined position (contacted portion 43) of the support shaft 3 with which the inner peripheral surface of the shaft hole 41 contacts.
Is on the side opposite to the side where the lens holder 10 is located in the circumferential direction of the support shaft 3. For this reason, when viewed from the shaft hole 41, the central axis H of the rotational driving force comes to a position on the opposite side to the objective lens 10, so that the drive coil 53 and the like are disposed on the opposite side with respect to the objective lens 10. Good. Therefore, there is an advantage that the lens holder 4 can be easily designed in terms of the layout surface of the lens holder 4 and the balance of the center of gravity.

[Other Embodiments] In the above embodiment, the central axis H of the rotational driving force completely passes through a predetermined position (contacted portion 43) of the support shaft 3 with which the inner peripheral surface of the shaft hole 41 contacts. However, the side pressure M is applied when the central axis H of the rotational driving force is viewed from the support shaft 3 beyond a predetermined position (contacted portion 43) of the support shaft 3 where the inner peripheral surface of the shaft hole 41 contacts. In this case, it is possible to prevent the lens holder 4 from rattling even when the lens holder 4 passes through the lens holder 4 (the side opposite to the side on which the objective lens 10 is located).

In the above embodiment, the objective lens 1
Although the center of gravity G of the lens holder 4 including 0 is overlapped with a predetermined position (contacted portion 43) of the support shaft 3 with which the inner peripheral surface of the shaft hole 41 contacts, when viewed from the support shaft 3 , Shaft hole 4
1 at a predetermined position of the support shaft 3 with which the inner peripheral surface of the
(3) the side pressure M is applied more than (3)
Even when the center of gravity G is located on the side opposite to the side where is located, it is possible to suppress a rotational moment that causes rattling of the lens holder 4.

[0040]

As described above, in the optical head device of the present invention, the lens holder makes the inner peripheral surface of the shaft hole contact the predetermined position in the circumferential direction of the support shaft by the side pressure, A magnetic drive circuit applies a rotational driving force to the lens holder at a predetermined position or at a position where the lateral pressure is applied when viewed from the support shaft with respect to the predetermined position. For this reason, the lens holder rotates while the inner peripheral surface of the shaft hole is in contact with a predetermined position in the circumferential direction of the support shaft. Therefore, no rattling occurs between the shaft hole of the lens holder and the support shaft, so that the optical head device has improved seismic resistance and stable operation.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an optical head device to which the present invention is applied.

FIG. 2 is a plan view showing a positional relationship among an objective lens, a lens holder, a support shaft, and a tracking drive magnet in the optical head device according to the first embodiment of the present invention.

FIG. 3 is a plan view showing a positional relationship among an objective lens, a lens holder, a support shaft, and a tracking drive magnet in the optical head device according to Embodiment 2 of the present invention.

FIGS. 4A and 4B are a plan view and a side view, respectively, showing a positional relationship among an objective lens, a holder, a support shaft, and a tracking drive magnet in a conventional optical head device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical head apparatus 2 Frame 3 Support shaft 4 Lens holder 10 Objective lens 41 Shaft hole 42 Contact part 44 Bearing part 51, 52 Tracking drive magnet 53 Tracking drive coil 54 Magnetic piece 61, 62 Focusing drive magnet 63 Focusing drive coil M Side pressure Direction T1, T2 Tracking direction G Center of gravity H Central axis of rotational driving force

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5D118 AA23 BA01 BB02 BF02 BF03 EA02 ED06 ED08 FA07 FB08 5D119 AA39 BA01 DA01 DA05 JA43 JC00 NA07

Claims (5)

[Claims] 1. A frame having a lens holder having a shaft hole formed therein, and a frame having a support shaft fitted in the shaft hole, the lens holder holding an objective lens for converging light emitted from a light source on an optical recording medium. An optical head device having at least a magnetic drive circuit capable of driving the lens holder to rotate about the support shaft, wherein the lens holder has an inner peripheral surface of the shaft hole formed by the support shaft by a side pressure applied to the lens holder. The magnetic drive circuit contacts the predetermined position in the circumferential direction on the outer peripheral surface of the support shaft, and the magnetic drive circuit, when viewed from the support shaft relative to the predetermined position of the support shaft with which the inner peripheral surface of the shaft hole contacts, or An optical head device, wherein a rotational driving force whose central axis passes through a position to which a side pressure is applied is applied to the lens holder. 2. The lens driving device according to claim 1, wherein the magnetic drive circuit applies a rotational driving force to the lens holder, the central axis passing through a predetermined position of the support shaft with which the inner peripheral surface of the shaft hole contacts. An optical head device characterized in that: 3. The lens holder according to claim 1, wherein the lens holder is located at a position overlapping with a predetermined position of the support shaft with which an inner peripheral surface of the shaft hole contacts, or when viewed from the support shaft with respect to the predetermined position. An optical head device having a center of gravity at a position to which a lateral pressure is applied. 4. The optical head device according to claim 3, wherein the lens holder has a center of gravity at a position overlapping a predetermined position of the support shaft with which an inner peripheral surface of the shaft hole contacts. 5. The predetermined position of the support shaft with which the inner peripheral surface of the shaft hole contacts is located on a side of the circumferential direction of the support shaft opposite to a side on which the lens holder is located. An optical head device comprising: