JP2571211B2 - Optical head device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head device, and more particularly, to an optical head device that records or reproduces information while moving relative to an information recording carrier.

(Prior art)

Conventionally, an optical head device has a housing and an optical system driving device provided thereon. Hereinafter, this optical system driving device will be described by taking an objective lens driving device as an example.

 FIG. 7 is a perspective view of a conventional objective lens driving device.

As shown in FIG. 7, the objective lens holder 42 is inserted through a bearing into a support shaft 40 fixed to a base 45 by press fitting or the like. A weight 43 having substantially the same weight as the objective lens 37 is attached. Further, a neutral point holding member (not shown) is attached below the weight 43. A focusing coil 38 is wound around the outer periphery of the objective lens holder 42. Further, a tracking coil 39b and a tracking coil 39a (not shown)
About 40, it is attached to the position opposite to the tracking coil 39b. ) Is attached. Permanent focusing magnets 41a and 41b are fixed to the base 45 near the inner peripheral portion of the objective lens holder 42 so as to face the focusing coil 38, and near the outer peripheral portion.
The yokes 44a and 44b forming the opposing magnetic pole of 41b are fixed.
Also, facing the tracking coils 39a and 39b,
Tracking permanent magnets 46a and 46b are fixed to the base 45 near the outer peripheral portion of the objective lens holder. By the electromagnetic force generated by the current flowing through the focusing coil 38 and the tracking coils 39a and 39b and the magnetic field formed for each coil, the objective lens holder 42 slides up and down around the support shaft 40, It is rotated left and right.

[Problems to be solved by the invention]

However, a base 45 is provided for fixing the tracking permanent magnets 46a, 46b, the focusing permanent magnets 41a, 41b, the yokes 44a, 44b, and the support shaft 40 to the objective lens driving device. Since the objective lens driving device is fixed to the housing by screwing the optical head device into the housing, the weight of the optical head device becomes heavy, and it takes time to mount the optical head device. Support shaft 45 for housing
Is mounted through the base 45, so that the support shaft 40
In addition, there is a problem that the accuracy with respect to the inclination of the optical system of the housing with respect to the optical axis is apt to decrease.

An object of the present invention is to provide an optical head device that is lightweight and has high accuracy with respect to the inclination of a support shaft.

[Means for solving the problem]

The above-mentioned problem is caused in an optical head device for recording or reproducing information on or from an information recording carrier, a housing having an optical component installed, which is relatively moved with respect to the information recording carrier, and a support which is directly press-fitted and fixed to the housing. A shaft, an objective lens holder movably supported by the support shaft, a plurality of coils fixed to the objective lens holder, and a magnetic field directly applied to the housing and applying a magnetic field to the coil. The problem is solved by the optical head device of the present invention having a magnetic circuit including a magnet and a yoke arranged opposite to the magnet.

[Action]

The present invention reduces the weight of an optical head device by directly attaching a support shaft and a magnetic circuit to a housing in which an optical component is installed, and provides an optical system with high accuracy with respect to the inclination between the support shaft and the optical axis of the optical system of the housing. A head device is provided.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an assembled perspective view of a first embodiment of the optical head device according to the present invention.

In FIG. 1, the objective lens holder 1 is inserted into a support shaft 11 via a bearing 14. In the vicinity of the bearing 14, the objective lens 2 and the objective lens 2
A weight 12 of approximately the same weight as is attached. A focusing coil 3 is wound around the outer periphery of the objective lens holder 1, and a substantially rectangular tracking coil is provided thereunder.
4a and 4b are attached.

The support shaft 11 is directly fixed to the housing 9 by press-fitting or the like, and can easily tilt the optical system provided in the housing 9 from the optical axis.
It can be suppressed to 0.1 mm or less. The housing 9 is provided with a tracking permanent magnet near the outer periphery of the objective lens holder 1 so as to face the tracking coils 4a and 4b.
7a and 7b, 7c and 7d and their tracking permanent magnets 7a
The non-magnetic members 13a to 13f are respectively fixed so as to sandwich .about.7d. Although the tracking coil 4a, the tracking permanent magnets 7a and 7b, and the nonmagnetic material 13b are not shown,
With respect to 11, the tracking coils 4b, the tracking permanent magnets 7c and 7d, and the non-magnetic material 13e are respectively mounted at positions opposite to each other.

Tracking permanent magnets 7a to 7d and non-magnetic bodies 13a to 13f
The focusing permanent magnets 6a and 6b are fixed on the upper surface of the lens so as to face the focusing coil 3. The yokes 8a and 8b as opposed magnetic poles of the tracking permanent magnets 7a to 7b and the focusing permanent magnets 6a and 6b are fixed to the housing 9 near the inner peripheral portion of the objective lens holder 1 and opposed to the inner peripheral portion. Is done.

In the objective lens driving device according to the present invention, since the focusing coil 3 and the tracking coils 4a and 4b are separately mounted, the focusing permanent magnets 6a and 6b and the tracking permanent magnets 7a to 7d and the yokes 8a and 8b Are narrower than in the conventional example shown in FIG. 7 and the magnetic flux density is increased.

The tracking permanent magnets 7a to 7b, the yokes 8a and 8b, and the non-magnetic members 13a to 13f are directly attached to the housing 9 with an adhesive or the like.

The focus control is performed by sliding the objective lens holder 1 up and down around the support shaft 11 by an electric current flowing through the focusing coil 3 and an electromagnetic force generated by the magnetic field generated by the focusing permanent magnets 6a and 6b. The control is performed by rotating the objective lens holder 1 right and left around the support shaft 11 by an electromagnetic force generated by a current flowing through the tracking coils 4a and 4b and a magnetic field generated by the tracking permanent magnets 7a to 7d.

The neutral point holding rubber 5 fixed to the housing 9 holds the neutral point of the objective lens holder 1. The objective lens holder 1 can be rotated left and right and vertically slid within the holding range.

There are various drive systems for the housing 9,
Here, the embodiment using the linear motor capable of the high-speed access operation has been described. 10a and 10b are rails, 17 is a linear motor coil, 16 is a magnet, and 15 is a yoke.

FIG. 2 is a longitudinal sectional view in the direction of the optical head device AA 'when the objective lens holder is incorporated.

As shown in FIG. 2, when the focusing permanent magnets 6a and 6b and the tracking permanent magnets 7a and 7c are placed in parallel with different polarities, no magnetic field is generated perpendicular to each coil, and focus control is performed. Since the tracking control becomes impossible, the same poles are placed in parallel. The focusing permanent magnets 6a and 6b and the tracking permanent magnets 7b and 7d are similarly mounted. Permanent magnet for tracking
Non-magnetic members 13a to 13f are provided between 7a, 7b, 7c and 7d to prevent disturbance of the magnetic field. In this embodiment, the tracking coil 4
Although an example in which four tracking permanent magnets 7a to 7d are provided for two a and 4b is shown, the present invention is also applicable to other examples, for example, when two tracking permanent magnets are provided for four tracking coils. The invention is applicable.

Inside the housing 9, a laser light source 18, a collimator lens 19, a beam shaping prism 20, a beam splitter 21, a condenser lens 22, a half mirror 23, a detector 24a,
An optical system including optical components such as 24b is installed.

In another embodiment of the present invention described below,
The same members as those in the first embodiment shown in FIGS. 1 and 2 are denoted by the same reference numerals, and the same components will not be described repeatedly.

FIG. 3 is an assembled perspective view of a second embodiment of the optical head device according to the present invention. FIG. 4 is a longitudinal sectional view in the AA 'direction of the optical head device when the objective lens holder is incorporated. In the present invention, a tracking coil is used for simplicity.
Only the tracking drive unit for 4b will be described, and description of the tracking coil 4a will be omitted, but the configuration is the same.

As shown in FIGS. 3 and 4, in this embodiment,
The tracking drive of the objective lens drive is provided in the housing 9. That is, the housing 9 is provided with a tracking hole 29 corresponding to the rotation range of the mounting portion of the tracking coil 4b of the objective lens holder 1, and the tracking hole 29 is provided so as to face the inserted tracking coil 4b. The permanent magnets 7c and 7d for tracking and the non-magnetic material 13e are buried in the vicinity of the outer peripheral portion of the mounting portion of the coil 4b, and the yoke hole 26 is provided in the vicinity of the inner peripheral portion, and the yoke 8b is buried approximately half. . Tracking permanent magnet 7
At one end of c and 7d, the permanent magnet for focusing 6b mounting grooves 27 and 2
8 are provided. The housing 9 is provided with a hole 25 corresponding to the movable range of the objective lens 2.

Since the objective lens driving device according to the present embodiment can omit the non-magnetic members 13a, 13c, 13d, and 13f according to the first embodiment, the number of parts can be reduced, and the tracking driving unit can be embedded. Therefore, even if the size of the objective lens holder 1 is increased, the size of the entire optical head device is not increased.

Further, in the present embodiment, it is not always necessary to bury the yokes 8a, 8; however, it is possible to form the opposing magnetic poles of the tracking permanent magnets 7a to 7d to increase the magnetic field strength applied to the tracking coils 4a, 4b. It is preferable to bury it because it is possible.

FIG. 5 is a perspective view of a third embodiment of the optical head device according to the present invention.

In FIG. 5, the objective lens 2 is fixed to the lens barrel 32,
The lens barrel 32 is supported by a bearing arm 33 and is provided to be vertically slidable in the optical axis direction of the objective lens 2. Lens barrel
A focusing coil 3 is wound around the outer periphery of the lower end of 32.
A cylindrical focusing permanent magnet 6 is embedded in the housing 9. The bearing arm 33 is inserted into a support shaft 11 directly fixed to the housing 9 and is fixed by stoppers 30 and 31 so as to be able to rotate left and right about the support shaft 11. A tracking coil 4 is fixed to the outer peripheral portion of the lens barrel supporting portion of the bearing arm 33, and a columnar tracking permanent magnet 7 is fixed to the housing 9 so as to face the tracking coil 4.

Focus control is performed by sliding the lens barrel 32 up and down by an electromagnetic force generated by a current flowing through the focusing coil 3 and a magnetic field generated by the focusing permanent magnet 6. This is performed by rotating the bearing arm 33 supporting the lens barrel 32 right and left around the support shaft 11 by the electromagnetic force generated by the magnetic field generated by the tracking permanent magnet 7. The neutral point is held by fixing a neutral point holding mechanism (not shown) made of an elastic body such as rubber to the bearing arm 33.

FIG. 6 is a perspective view of a fourth embodiment of the optical head device according to the present invention.

In FIG. 6, the objective lens holder 1 has two leaf springs.
It is supported by one end of 35 and is provided so as to be movable in the optical axis direction of the objective lens 2. The other end of the leaf spring 35 is the relay plate 34
The relay plate 34 is rotatable left and right around the support shaft 11 directly fixed to the housing 9.
The vertical direction of the support shaft 11 is regulated by the stopper 30. The weight balance is maintained by providing the balancer 36 in the direction opposite to the objective lens holder 1 about the support shaft 11. The neutral point of the objective lens holder 1 in the optical axis direction is held by a leaf spring 35. Objective lens holder 1
A focusing coil 3 is wound around the outer periphery of
A substantially rectangular tracking coil 4 is fixed on the focusing coil 3. A focusing permanent magnet 6 is fixed on the housing 9 so as to face the focusing coil 3, and two tracking permanent magnets 7 are fixed near the objective lens holder 1 so as to face the tracking coil 4. You.

The description of the focus control and the tracking control is substantially the same as that of the third embodiment shown in FIG.

〔The invention's effect〕

As described in detail above, the optical head device of the present invention reduces the weight of the optical head device by directly attaching the support shaft and the magnetic circuit to the housing in which the optical components are installed, thereby reducing the weight of the support shaft and the housing. The precision with respect to the inclination of the optical system with respect to the optical axis has been improved, and high-precision and high-speed access of the optical head device has been enabled.

[Brief description of the drawings]

FIG. 1 is an assembled perspective view of a first embodiment of the optical head device according to the present invention. FIG. 2 shows the first case where the objective lens holder is incorporated.
FIG. 3 is a vertical sectional view of the optical head device of the embodiment in the AA ′ direction. FIG. 3 is an assembled perspective view of a second embodiment of the optical head device according to the present invention. FIG. 4 shows the second case where the objective lens holder is incorporated.
FIG. 3 is a vertical sectional view of the optical head device of the embodiment in the AA ′ direction. FIG. 5 is a perspective view of a third embodiment of the optical head device according to the present invention. FIG. 6 is a perspective view of a fourth embodiment of the optical head device according to the present invention. FIG. 7 is a perspective view of a conventional objective lens driving device. 2 ... Objective lens, 3 ... Coil for focus, 4,4a, 4
b: Tracking coil, 6, 6a, 6b: Focusing permanent magnet, 7, 7a, 7b, 7c, 7d: Tracking permanent magnet, 8a, 8b: Yoke, 9: Optical component holding member 11…
... support shaft.

Claims (1)

(57) [Claims] 1. An optical head device for recording or reproducing information on or from an information recording carrier, comprising: a housing having an optical component mounted thereon, said housing moving relative to said information recording carrier; and a support shaft directly press-fitted and fixed to said housing. An objective lens holder movably supported by the support shaft; a plurality of coils fixed to the objective lens holder; and a permanent magnet directly fixed to the housing and applying a magnetic field to the coil. An optical head device comprising: a magnetic circuit comprising: a yoke disposed opposite to the magnetic circuit;