JPH0454566Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field] The present invention relates to an optical pick-up installed in a compact disc player, etc., and in particular, a lens holder that holds an objective lens is supported by a leaf spring so as to be movable in the focus correction direction. This invention relates to an objective lens support device.

[Background of the idea]

FIG. 4 is a side view showing a conventional objective lens support device for an optical pickup, and FIG. 5 is a plan view thereof.

In the figure, reference numeral 1 denotes an objective lens facing the optical disk D. Objective lens 1 is in lens holder 2
is maintained. The lens holder 2 is supported by a leaf spring 3 so as to be able to move slightly in the direction of the optical axis of the objective lens 1 (Y direction). The base end of the leaf spring 3 is fixed to a rotating frame 4, and this rotating frame 4 is provided with a support shaft 5, which is rotatably supported by a bearing 6 on the chassis side. ing. The lens holder 2 rotates around the support shaft 5 in a direction along the recording surface of the optical disk D (θ direction).
It can be rotated freely.

The lens holder 2 is provided with a tracking coil 7 and a focusing coil (not shown). A magnet 9 held by a yoke 8 faces the tracking coil 7, and another magnet faces the focusing coil. The lens holder 2 is driven in the Y direction and the θ direction by this correction drive mechanism (not shown). By driving the lens holder 2 in the Y direction, the focus of the spot of the laser beam irradiated from the objective lens 1 is corrected so as to always be on the recording surface of the optical disk D (focus correction). Further, by driving the lens holder 2 in the θ direction, the laser beam spot is corrected so as to accurately scan the information track on the recording surface of the optical disk D (tracking correction).

[Problem that the invention attempts to solve]

In the objective lens support device having the above structure, the leaf spring 3
is provided for focus correction drive,
In the focus correction operation of the objective lens 1, it is assumed that the leaf spring 3 deforms only in the Y direction. However, in reality, due to the driving force in the θ direction by the tracking coil 7 and other forces,
As shown in an exaggerated manner in FIG. 6, the leaf spring 3 may deform in the width direction. This deformation causes sub-resonance in the vibration system formed by the lens holder 2 and the leaf spring 3, resulting in vibration in a high frequency range of about 2 to 3 KHz. If this sub-resonance occurs, it will affect the original tracking correction operation of the objective lens 2, resulting in a decrease in tracking correction accuracy.

The present invention solves the above-mentioned conventional problems, and even if sub-resonance occurs due to the deformation of the leaf spring as shown in Fig. 6, it does not affect the tracking correction operation of the objective lens. The present invention provides an objective lens support device for an optical pickup.

[Specific measures to solve the problem]

In the present invention, a lens holder holding an objective lens facing an optical disk is supported by a plate spring arranged parallel to the recording surface of the optical disk, and the lens holder is In an objective lens support device for an optical pickup that is provided with a correction drive mechanism that drives in the axial direction and in the direction orthogonal to the optical axis of the objective lens,
The optical axis of the objective lens is located at a position opposite to the leaf spring support side with respect to the center of the lens holder,
The present invention is characterized in that the leaf spring is disposed at a position that substantially coincides with a deformation node when the leaf spring deforms in a direction perpendicular to the optical axis of the objective lens due to sub-resonance.

[Effect]

The principle of this objective lens support device will be explained. As shown in FIG. 5, conventionally, the objective lens 1
The optical axis of the lens holder 2 is located at the center of the lens holder 2 and is located approximately on the center of gravity G, and the trucking coil 7
Generally, the center of action of the driving force is also located approximately on the same line as the center of gravity G. However, when the leaf spring 3 vibrates in the sub-resonance direction shown in FIG. 6, the vibration node O is located outside the center of gravity G of the lens holder 2 (to the left in the figure). Therefore, when sub-resonance occurs due to the deformation of the leaf spring 3 in the width direction, the optical axis of the objective lens 1, which is located approximately on the center of gravity G, is swung around the node O, as shown in FIG. , and this contact of the optical axis has a negative effect on tracking correction.
The present invention focuses on the principle of operation of such leaf springs due to sub-resonance, and the position of the optical axis of the objective lens is biased in the direction opposite to the support side of the leaf spring in the lens holder. The optical axis is made to almost coincide with the node O of vibration of the sub-resonance. As a result, even if sub-resonance as shown in FIG. 6 occurs, the position of the optical axis of the objective lens will not change, and the tracking correction operation will not be affected.

[Example of idea]

Embodiments of the present invention will be described below with reference to the drawings of FIGS. 1 to 3.

FIG. 1 is a perspective view of an objective lens support device of an optical pickup according to the present invention, FIG. 2 is a plan view showing a lens holder portion, and FIG. 3 is an explanatory view showing the influence of vibration.

In FIG. 1, reference numeral 11 is an objective lens facing an optical disk (not shown). The objective lens 11 is held by a lens holder 12. The lens holder 12 has two leaf springs 1 arranged in parallel.
3, the objective lens 11 is supported so as to be slightly movable in the direction of the optical axis (Y direction). The base end of the leaf spring 13 is fixed to the rotating frame 14. This rotating frame 14 is provided with a support shaft 15, and this support shaft 15 is rotatably supported by a bearing provided on the chassis. The lens holder 12 is rotatable about the support shaft 15 in a direction (θ direction) along the recording surface of the optical disk. Reference numeral 16 is a tracking spring. This tracking spring 16 moves the lens holder 12 at θ
It returns to the neutral position in the direction, and its tip is fixed to the chassis.

As shown in FIG. 2, the optical axis of the objective lens 11 is held at a position offset from the center of the lens holder 12 (approximately coinciding with the center of gravity G) toward the side opposite to the leaf spring support side. By selecting this amount of deviation, the node O of the deformation of the leaf spring 13 as shown in FIG.
The optical axes of the objective lens 1 can be made to substantially coincide with each other. This amount of deviation can be easily set by actually conducting vibration experiments and examining vibration nodes.

Further, as shown in FIG. 1, a tracking coil 17 and a focusing coil 18 are provided on both sides of the lens holder 11. A magnet (not shown) faces the tracking coil 17 and the focusing coil 18. Second
As shown in the figure, the center line of action of the tracking correction driving force by the tracking coil 17 almost coincides with the position passing over the center of gravity G of the lens holder 12.

Next, the operation of this optical pickup will be explained.

The lens holder 12 has a focusing coil 18
It is driven in the Y direction by a correction drive mechanism composed of a magnet and a magnet provided opposite thereto. Through this operation, the detection beam irradiated from the objective lens 11 onto the recording surface of the optical disk is corrected so that the spot is always in focus (focusing correction). Also, tracking coil 17
The lens holder 12 is driven in the θ direction by a correction drive mechanism constituted by a magnet provided opposite to the lens holder 12, and the spot of the detection beam irradiated from the objective lens 11 detects information on the recording surface of the optical disk. The track is corrected to scan accurately (tracking correction).

Further, the leaf spring 13 is deformed in the direction shown in FIG.
High frequency sub-resonance may occur in the vibration system due to However, since the optical axis of the objective lens 11 is provided at a position that almost coincides with the node O of the vibration of the above-mentioned sub-resonance, even if the above-mentioned sub-resonance occurs and the center of gravity G of the lens holder 12 swings, the objective lens 11 The position of the optical axis of the lens 11 does not change.
Therefore, the tracking correction of the objective lens 11 is not affected by the sub-resonance.

[Effect of idea]

As described above, according to the present invention, even in an objective lens support device in which the lens holder is movable in the optical axis direction of the objective lens by means of a leaf spring, the vibration of the leaf spring in the lateral direction Sub-resonance no longer has a negative effect on tracking correction,
A highly accurate tracking correction operation can now be performed.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the objective lens support device for an optical pickup according to the present invention, FIG. FIG. 4 is a side view showing an objective lens support device of a conventional optical pickup; FIG. 5 is a plan view thereof; and FIG. FIG. 11...Objective lens, 12...Lens holder,
13... Leaf spring, 14... Rotating frame, 15...
...Support shaft, 17...Tracking coil, 18...
...Focusing coil.

Claims (1)

[Scope of utility model registration request] A lens holder holding an objective lens facing the optical disk is supported by a leaf spring arranged parallel to the recording surface of the optical disk, and the lens holder is held in the optical axis direction of the objective lens and the objective lens. In an objective lens support device for an optical pickup that is provided with a correction drive mechanism that drives in a direction perpendicular to the optical axis of the lens, the optical axis of the objective lens is on the side opposite to the leaf spring support side with respect to the center of the lens holder. An optical pick-up characterized in that the leaf spring is disposed at a position biased to substantially coincide with a deformation node when the leaf spring is deformed in a direction perpendicular to the optical axis of the objective lens due to sub-resonance. objective lens support device.