JPH0644579A - Objective lens drive - Google Patents

Abstract

PURPOSE:To cancel inertial force by coupling a canceling spring symmetrical with a track spring holding an objective lens with a column, fitting a balancer atop and bringing two auxiliary arm other-end sides with both ends of the track spring and clamping the spring. CONSTITUTION:A movable member 3 holding the objective 2 is coupled with the base column 12 though one track spring 10 provided orthogonally with a recording medium. The movable member 3 is moved by the deflection of the track spring 10 to drive the objective 2 in a track direction. Then the canceling spring 18 is coupled with the base column 12 symmetrically with the track spring 10 and the balancer 14 is fitted atop of it. Then other-end sides of the auxiliary arms 13a and 13b whose one-end sides are coupled with the balancer 14 are brought into contact with both the ends of the track spring 10 to clamp the track spring 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens driving device used in an optical information recording device and for driving an objective lens for focusing laser light on a recording medium.

[0002]

2. Description of the Related Art An optical information recording apparatus includes an objective lens so that laser light emitted from a semiconductor laser light source can be accurately focused on a recording medium to optically record and reproduce information. Is provided with a support mechanism that supports the lens so that it can freely move in a focus direction perpendicular to the recording medium, and a track direction parallel to the radial direction of the recording medium, and a drive mechanism that moves in those directions. . These mechanisms generally utilize spring support means and electromagnetic drive means by coils and magnets.

FIG. 4 is a plan view showing an example of such a conventional objective lens driving device.

In FIG. 4, the movable member 23 holding the objective lens 22 is connected to a track holder 31 via a focus spring 29, and the track holder 31 is connected to a base support column 32 via a track spring 30. There is. When the focus spring 29 bends, the movable member 2
3, the objective lens 22 is driven in the focus direction (direction perpendicular to the paper surface), and the track spring 30 bends to drive the objective lens 22 in the track direction (vertical direction in the figure) via the movable member 23. . These movements are performed by the focus coil 27 and the track coils 28a and 28b provided on the movable member 23, and the magnets 24a and 24b and the yokes 26a and 2 fixed to the base 21.
It is driven by the electromagnetic force due to the magnetic field between 6b.

The objective lens driving device thus constructed is mounted on a carriage and moves in the track direction integrally with the carriage (see FIG. 3).

[0006]

In the conventional objective lens driving device as described above, when the current is applied to the coil to displace the movable member in the track direction, the acceleration is the mass of the movable member, the outer shape of the coil and the magnet. There is a limit depending on the strength, etc., and it is difficult to design a value with a sufficient margin more than necessary. Further, when the objective lens driving device moves (seeks) in the track direction integrally with the carriage, it causes a swinging phenomenon due to inertial force, so that the center position of the movable member does not shift by passing a current through the track coil. Although the information is read out from the recording medium in such a manner that it can be instantaneously read, there is a problem in that the high speed seek cannot be performed sufficiently.

[0007]

An objective lens driving device of the present invention is an objective lens for converging a laser beam on a recording medium, a movable member for holding the objective lens, and the movable member for the recording medium. 4 focus springs that are movably held in the vertical direction, one track spring that is fixed to a base column that holds the movable member movably in the radial direction of the recording medium, and the movable member. A track coil fixed to a member to drive the movable member in the track direction, a focus coil fixed to the movable member to drive the movable member in the focus direction, and provided to face the track coil and the focus coil. A magnetic circuit including a magnet fixed to a base and a yoke, and an objective lens driving device comprising: Fixed to the base struts referred 1
A sheet of cancel springs, a balancer attached to the tip of the cancel springs, and two auxiliary arms that are fixed to the balancer at one end and contact and clamp the track spring at the other end are provided.

[0008]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a plan view showing an embodiment of the present invention, FIG. 2 is a front view of the embodiment of FIG. 1, and FIG. 3 is a perspective view showing a state where the embodiment of FIG. 1 is mounted on a carriage.

In FIGS. 1 and 2, a movable member 3 for holding an objective lens 2 is provided with a track holder 1 via four focus springs 9 arranged in parallel with a recording medium.
The track holder 11 is connected to the base column 12 via one track spring 10 arranged perpendicularly to the recording medium. When the focus spring 9 bends, the objective lens 2 passes through the movable member 3.
Is driven in the focus direction (direction perpendicular to the paper surface in FIG. 1), and the objective lens 2 is driven in the track direction (vertical direction in FIG. 1) via the movable member 3 by the flexure of the track spring 10. These movements are driven by an electromagnetic force by a magnetic field between the focus coil 7 and the track coils 8a and 8b provided on the movable member 3 and the magnets 4a and 4b and the yokes 6a and 6b fixed to the base 1. .

A parallel magnetic field is formed between the magnet 4a and the yoke 6a and between the magnet 4b and the yoke 6b in a direction perpendicular to the focus direction and the track direction. It is wound in the track direction, and the track coils 8a and 8b are wound in the focus direction. Therefore, when an electric current is passed through the focus coil 7, an electromagnetic force is generated in the focus direction which is the optical axis direction of the objective lens 2, and an electric current is passed through the track coils 8a and 8b, so that the objective lens 2 is moved.
Electromagnetic force is generated in the track direction, which is the direction perpendicular to the optical axis direction of. By these electromagnetic forces, the movable member 3 holding the objective lens 2 can be driven in the biaxial directions.

As shown in FIG. 3, the objective lens driving device 17 thus constructed is mounted on the carriage 15 and moves integrally with the carriage 15 in the track direction (direction A) to move the recording medium to the top. A seek movement is performed between the inner circumference and the outermost circumference along the rails 16a and 16b.

The acceleration of the movable member 3 caused by passing a current through the track coils 8a and 8b is the mass of the movable member 3, the outer shape of the track coils 8a and 8b, and the magnets 4a and 4b.
There is a limit depending on the strength, etc., and it is difficult to design a value with a sufficient margin more than necessary. Further, when the objective lens driving device 17 is integrated with the carriage 15 to seek in the track direction, the movable member 3 causes a swinging phenomenon due to its inertial force, and therefore the track coils 8a and 8b.
The central position of the movable member 3 is controlled so as not to shift by passing an electric current through it so that the information can be read out from the recording medium instantaneously. Disappear.

Therefore, as shown in FIG. 1 and FIG.
The cancel spring 18 is connected to the base strut 12 symmetrically with the track spring 10, and the balancer 14 is attached to the tip thereof.
The other ends of the auxiliary arms 13a and 13b having one ends connected to the balancer 14 are brought into contact with both sides of the track spring 10 to hold the track spring 10 therebetween.

With this structure, when the carriage 15 performs a high-speed seek operation, an inertial force acts on the movable member 3, but an inertial force also acts on the balancer 14 in the same direction. The inertial force acting on the balancer 14 is the auxiliary arm 13a.
And 13b are transmitted to the track spring 10 and the inertial force acting on the movable member 3 is transmitted to the movable member 3 as a force in the direction opposite to the direction transmitted to the track spring 10. Therefore, the swinging phenomenon of the movable member 3 is suppressed.

[0016]

As described above, in the objective lens driving device of the present invention, the cancel spring that is symmetrical to the track spring that holds the movable member that holds the objective lens so as to be movable in the track direction is coupled to the base column. Then, a balancer is attached to the tip of the cancel spring, and the other ends of the two auxiliary arms connected to the balancer are brought into contact with both sides of the track spring so that they are clamped, so that the carriage performs a high-speed seek operation. There is an effect that the inertial force acting on the movable member can be canceled and the swinging phenomenon of the movable member can be suppressed. Therefore, there is an effect that the information reading operation of the optical information recording device can be speeded up.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

2 is a front view of the embodiment of FIG. 1. FIG.

FIG. 3 is a perspective view showing a state where the embodiment of FIG. 1 is mounted on a carriage.

FIG. 4 is a plan view showing an example of a conventional objective lens driving device.

[Explanation of symbols]

 1.21 base 2.22 objective lens 3.23 movable member 4a / 4b / 24a / 24b magnet 6a / 6b26a26b yoke 7/27 focus coil 8a / 8b / 28a / 28b track coil 9/29 focus spring 10・ 30 track springs 11 ・ 31 track holders 12 ・ 32 base columns 13a ・ 13b auxiliary arms 14 balancers 15 carriages 16a ・ 16b rails 17 objective lens drive device 18 cancel springs

Claims (2)

[Claims] 1. A movable member that holds an objective lens that focuses a laser beam on a recording medium, and a track spring that is fixed to a base column by holding the movable member so as to be movable in the radial direction of the recording medium. And an objective lens drive including a track coil fixed to the movable member to drive the movable member in the track direction, and a magnetic circuit including a magnet and a yoke provided facing the track coil and fixed to a base. In the device, one cancel spring fixed to the base column in symmetry with the track spring, a balancer attached to the tip of the cancel spring, one end fixed to the balancer and the other end contacting the track spring. The objective lens driving device is characterized in that it is provided with two auxiliary arms that are sandwiched between them. 2. An objective lens for converging laser light onto a recording medium, and a movable member for holding the objective lens.
Four focus springs that hold the movable member so as to be movable in the vertical direction with respect to the recording medium, and one piece that is fixed to the base support while holding the movable member so as to be movable in the radial direction of the recording medium. Track spring, a track coil fixed to the movable member to drive the movable member in the track direction, a focus coil fixed to the movable member to drive the movable member in the focus direction, the track coil and the track coil. In an objective lens driving device provided with a magnetic circuit including a magnet fixed to a base and facing a focus coil, and a yoke, one cancel spring fixed to the base column in symmetry with the track spring, A balancer attached to the tip of the cancel spring and one end fixed to the balancer An objective lens driving apparatus is characterized by providing the two auxiliary arms for clamping in contact with the track spring.