JPH077520B2 - Lens actuator - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system that records or reproduces information by condensing it at a desired position on a disc-shaped information recording medium (hereinafter referred to as a disc) using a laser or the like as a light source. The present invention relates to a lens actuator of a recording / reproducing apparatus.

2. Description of the Related Art As a conventional lens actuator, for example, JP-A-61-287
There is one shown in 051 publication.

FIG. 6 is a plan view of this conventional lens actuator, and FIG. 7 is a sectional view thereof.

104 is an objective lens, 106 is a lens barrel, 111 and 112 are elastic support members, 107 is a tracking drive coil, 109 is a focus drive coil, 108 is a tracking magnetic circuit, and 110 is a focus magnetic circuit. In this conventional lens actuator, a tracking correction current is supplied from a tracking error detection means (not shown) to the tracking drive coil 10.
7, the electromagnetic force is generated between the objective lens 104 and the tracking magnetic circuit 108, and the objective lens 104 moves in the XX direction in the figure until the elastic force of the elastic supporting members 111 and 112 is balanced, and tracking control is performed. . Similarly, focusing control is performed by moving the objective lens 104 in the Z-Z direction by the electromagnetic force between the focus drive coil 109 and the focusing magnetic circuit 110.

Problems to be Solved by the Invention However, in the above configuration, as shown in FIGS. 6 and 7, the objective lens 104 is caused by the translational force generated between the tracking drive coil 107 and the tracking magnetic circuit 108. , XX movement is performed to perform tracking control. Therefore, when seeking the optical head from one track to another track, the objective lens 104 receives a translational force in the XX direction due to the propulsive force of the seek mechanism such as a linear motor and is displaced in the tracking control direction, so that the seek operation is performed. The objective lens 104 vibrates in the tracking control direction due to the fluctuation of the driving force therein. As a result, when the seek operation by the seek mechanism is completed and the lens actuator performs the tracking pull-in, the relative displacement between the focused beam and the track becomes large because the objective lens 104 vibrates, so that the tracking pull-in and smooth movement cannot be performed.

Therefore, there is a problem that the seek time of the optical disk device becomes long.

In view of the above point, the present invention has an object to provide a lens actuator that can prevent the objective lens from vibrating during a seek operation and shorten the seek time of an optical disk device.

Means for Solving the Problems The present invention has a first movable body which houses an objective lens and has an opening near the center of gravity thereof, and a through hole which is located at the opening of the first movable body. A second movable body, a rotation shaft that is engaged with a through hole of the second movable body to rotatably support the second movable body, and is fixed to a housing, and one end of the rotation shaft. 1
A first elastic support member having elasticity in the focus control direction fixed to the rotating body and the other end fixed to the second movable body, and one end fixed to the second movable body and the other end fixed to the housing. A second elastic support member having elasticity in the rotating direction of the fixed second movable body, a first drive means for driving the first movable body in the focus control direction, and the first and second And a second drive means for rotating the movable body of FIG.

That is, the through hole for the objective lens through which the objective lens penetrates, the through hole for the rotating shaft through which the rotating magnetism penetrates, and a pair of notches parallel to the direction orthogonal to the tracking control direction.
Of a pair of first elastic support members in which a U-shaped notch is formed by continuing one notch provided between two through holes,
The first movable body is fixed to the through hole for the objective lens, the second rotating body is fixed to the through hole for the rotating shaft, and the second movable body and the case are fixed to each other by the second elastic support member. However, the pair of first elastic support members has elasticity only in the focus control direction, and the second elastic support member restricts the movement of the second movable body in the focus direction and elastically moves in the rotation axis direction. And a pair of focus drive coils fixed to the first movable body at positions symmetrical with respect to the rotation axis, and a first movable body and a focus drive coil at positions symmetrical with respect to the rotation axis. The lens actuator includes a pair of fixed tracking drive coils, and a magnetic circuit that generates a magnetic flux that links the focus drive coil and the tracking drive coil.

Effect of the Invention According to the present invention, the first movable body that houses the objective lens having the above-described configuration is connected by the elastic support member having elasticity only in the focus control direction, and the third movable body is located near the center of gravity of the first movable body. Tracking control is performed by rotating the movable body integrally with the movable body around a rotating shaft that engages with the second movable body. In addition, the second movable body is elastic in the rotating direction and has high rigidity in the ZZ direction. The first elastic support member having one end fixed to the second movable body fixed to the housing by the elastic support member supports the first movable body and moves up and down to perform focus control. The objective lens can be prevented from displacing in the tracking control direction even if the propulsive force of the seek mechanism during the seek operation acts as a translational force on the lens actuator, and the lens actuator after the seek operation is completed. Can be smoothly pulled in, and the seek time of the optical disk device can be shortened.

Embodiment FIG. 1 and FIG. 2 are a plan view and a front sectional view of a lens actuator according to an embodiment of the present invention, respectively.

Reference numeral 1 is an objective lens, and 2 is a first movable body having four openings in the vicinity of its center of gravity and accommodating the objective lens 1.

Reference numeral 5 denotes a second movable body which is located in the opening and has a through hole 6 itself. Reference numeral 3 denotes a focus control direction in which one end is fixed to the first movable body 2 and the other end is fixed to the second movable body 5 ( ZZ direction)
A pair of first elastic support members having elasticity only in the.
The second movable body 5 is engaged with the through hole 6 of the second movable body 5.
A rotary shaft that rotatably supports the first movable body 2 connected by the second movable body 5 and the first elastic support member 3, and is fixed to the housing 12 of the entire lens actuator. Reference numeral 8 is a second elastic support member having one end fixed to the second movable body 5 and the other end fixed to the housing 12 and having elasticity in the θ-θ direction. Reference numeral 9 denotes a pair of focus coils fixed to the first movable body 2 at positions whose centers are symmetrical with respect to the rotating shaft 7. Reference numeral 10 is a tracking coil fixed to the first movable body 2 and the focus coil 9 at a position whose center is symmetrical with respect to the rotating shaft 7. Reference numeral 11 denotes a magnetic circuit that generates a magnetic flux interlinking with the focus coil 9 and the tracking coil 10, and is fixed to the housing 12.

The operation of the lens actuator of the present embodiment configured as described above will be described with reference to FIGS. 1 to 5. FIG. 3 is an operation explanatory view of tracking control of the present embodiment, FIG. 4 is an operation explanatory view of focus control of the present embodiment,
FIG. 5 is an explanatory diagram of a seek operation using the lens actuator of this embodiment. Reference numeral 18 denotes a disk, 13 denotes an arbitrary track on the disk 18, and 14 denotes a track which is a track different from the track 13 on the disk 18. A carriage 15 moves the lens actuator in the XX direction in the drawing. Reference numeral 16 is a seek coil to which the carriage 15 is fixed, and 17 is a magnetic circuit which generates a magnetic flux interlinking with the seek coil 16.

First, the operation of tracking control will be described. Tracking control circuit (not shown) on tracking coil 10
When the tracking drive current is supplied from the magnetic circuit 11
An electromagnetic force in the Y-Y direction is generated between and. When the magnetic circuit 11 is configured so that these electromagnetic forces act in directions opposite to each other as indicated by T and −T in FIG. 3, the first movable body 3 and the second movable body 8 are Are connected by the first elastic support member, so that as shown in FIG. 3, M = T × l ₁ (l ₁ : center distance between the pair of tracking coils 10 about the axis of the rotating shaft 7). ) Moment is generated.

This moment M and the elastic force of the second elastic support member 8 are
The first movable body 3 and the second movable body 5 are formed at an equilibrium angle θ.
Rotate integrally with the rotary shaft 7. As a result ΔX = l ₂
The focusing position moves in the tracking control direction by xθ (l ₂ : the distance between the center of the rotary shaft 4 and the objective lens 1), and tracking control is performed.

Next, focus control will be described.

Focus control circuit (not shown) for the focus coil 9
When a focus drive current is supplied from the magnetic circuit 11, an electromagnetic force in the ZZ direction is generated with the magnetic circuit 11. Since the second movable body 5 is restricted from moving in the ZZ direction by the second elastic support member 8 due to this electromagnetic force, the first elastic support member 3 is moved to the ZZ direction as shown in FIG. The first movable body 2 accommodating the objective lens 1 that is elastically deformed as a fixed end at one end fixed to the second movable body 5 moves in the ZZ direction and focus control is performed.

As described above, according to the present embodiment, the tracking control is performed by integrally rotating the first movable body 2 and the second movable body 5 around the rotation shaft 7, and the focus control is performed by the second movable body. It can be performed by fixing the body 5 and translating only the first movable body 2.

Next, the operation of the lens actuator of this embodiment during the seek operation of the optical disk device will be described with reference to FIG. When a seek control circuit (not shown) supplies a seek drive current to the seek coil 16 when seeking from another track 13 on the disk 12 to another track 14, an electromagnetic force is generated between the seek magnetic circuit 17 and the seek magnetic circuit 17. F _S occurs, the carriage 15 moves from the track 13 toward the track 14, and the lens actuator moves to the track 14. At this time, the electromagnetic force F _S, which is a seek propulsion force, acts only as a translational force on the rotary shaft 7 that is easily placed near the center of gravity of the first movable body 2 and does not generate a moment. Therefore, the objective lens 1 does not vibrate in the XX direction due to the seek driving force, so that the tracking pull-in after the seek operation is smoothly performed, and the seek time of the optical disk device can be shortened.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to prevent the occurrence of vibration in the tracking control direction of the objective lens due to the seek propulsive force of the seek mechanism during the seek operation, and to perform the tracking pull-in smoothly after the seek operation ends. An actuator can be provided.

As a result, the seek time of the optical disk device can be shortened.

[Brief description of drawings]

1 and 2 are a plan view and a front sectional view showing an embodiment of the present invention, FIG. 3 is an operation explanatory view of tracking control of the embodiment of the present invention, and FIG. 4 is a focus control of the same embodiment. FIG. 5 is an operation explanatory view of the same embodiment at the time of seeking, and FIGS. 6 and 7 are a plan view and a front sectional view showing a conventional lens actuator. 1 ... Objective lens, 2 ... First movable body, 3 ... First elastic support member, 5 ... Second movable body, 7 ... Rotating shaft, 8
...... Second elastic support member.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sadao Mizuno 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-60-160031 (JP, A) JP-A-61-278045 (JP, A)

Claims (1)

[Claims] 1. An objective lens for focusing a light beam on a disk-shaped recording medium, a first movable body which houses the objective lens and has an opening near the center of gravity thereof, and an inside of the opening of the first movable body. And a second movable body having a through hole, and engaged with the through hole of the second movable body to rotatably support the second movable body and fixed to the housing. A rotary shaft, an objective lens through hole through which the objective lens penetrates, a rotary shaft through hole through which the rotary magnetism penetrates, and a pair of notches parallel to a direction orthogonal to the tracking control direction, The first movable member is provided in the through hole for the objective lens of the pair of first elastic supporting members having a U-shaped cutout which is a continuation of one cutout provided between two through holes. A body is fixed, the second movable body is fixed to the rotation shaft through hole, and the second movable body and the housing are fixed. Are secured by a second elastic support member, the pair of first elastic support members have elasticity only in the focus control direction, and the second elastic support member is in the focus direction of the second movable body. And a pair of focus driving coils fixed to the first movable body at positions symmetrical with respect to the rotation axis and having elasticity in the rotation axis direction. A pair of tracking drive coils fixed to the first movable body and the focus drive coil at symmetrical positions, and a magnetic field generating a magnetic flux that links the focus drive coil and the tracking drive coil. A lens actuator comprising: a circuit.