JPS6151628A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain accurate focus tracking control by fixing a balancer to a moving part including an objective lens supported freely movably in focus and tracking directions with a parallel spring so as to suppress resonance with simple structure. CONSTITUTION:The moving part is formed by fixing the objective lens 1 and the balancer 8 to an objective lens holder 2 fixed with a focus coil 6 and a track coil 7. The parallel spring 3 supports movably the moving part in the focus Z direction and the moving part around a shaft 4 freely turnably in the track direction Y. The balance 8 fixed to the lens holder 2 moves the center of gravity of the moving part on the center axis of the parallel spring and near the driving point A in the focus direction. Thus, a torque is applied to the center of gravity of the moving part in the directions Z, Y, the moment around the center of gravity is not acted to minimize the pitching in the direction Z and the yawing in the direction Y.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical information recording/reproducing device, and particularly to a two-axis actuator for performing focus control and tracking control.

[Conventional technology]

Conventionally, as shown in FIG. 2, the center of gravity of a moving unit consisting of an objective lens 1, an objective lens holder 2, a focus coil 6, and a track coil 7 is located from center points A and B of the forces generated in the focus coil and the track coil. They were far apart.

[Problem that the invention seeks to solve]

In the conventional structure, since the center of gravity of the moving part and the vital point of the driving force do not coincide, a moment around the center of gravity is generated, and a resonance phenomenon other than the desired parallel movement and rotational movement occurs.

[Means to solve the problem]

In order to solve all of the above problems, the present invention attaches a balancer to the objective lens holder to set the center of gravity of the movable part to coincide with or near the point of application of the ljA power in the two focus directions, thereby preventing harmful resonance. This was made to prevent this.

[For production]

In the optical information recording/reproducing device configured as above,
Since the driving forces in the focus direction 2 and the track direction Y act on the center of gravity of the movable part, no moment around the center of gravity acts, and pitching in the two directions and yawing in the Y direction can be minimized.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1A is a top view of this embodiment, and FIG. 1B is a sectional side view. The objective lens 1 and balancer 8 are fixed to the objective lens holder 2 to which the focus coil 6 and the track coil 7 are fixed to form the 0TIC 11 section, and this movable section is supported so as to be movable in parallel in the optical axis direction and in the focus direction 2. A parallel spring 3 is fixed to the right end of the objective lens holder. The other end of this parallel spring is fixed to the focus spring support 13, and is inserted into the entire bearing 5 of the shaft 4, which is integrated with or driven into the focus spring support, and the parallel spring is fully valved to align the movable part with the optical axis. It is possible to perform rotational movement in the orthogonal direction, that is, in the track direction Y. The balancer fixed to the objective lens holder is used to shift the center of gravity of the OT moving part to the vicinity of the driving point A in the focus direction, but its position is on the central axis of the parallel spring.
Furthermore, regarding the two directions, it is necessary to set them on the neutral plane of the parallel springs.

If this is not done, the movable part will rotate on the YZ plane and a resonance phenomenon of the macro ring will occur.

Next, to explain the operating state, the focus coil 6 is wound in the same direction around the circumference of the objective lens boulder 2, and the track coil 7 is wound in a rectangular or elliptical shape as shown in FIG. These coils are inserted into the gap between the magnetic circuit consisting of the yoke 12 and the magnet 11. Therefore, focus control can be performed by supplying a current proportional to the focus error signal to the focus coil 6, and tracking control can be similarly performed using the track coil 7. In FIG. 3, a balancer 8'f is attached to the objective lens holder 2: This shows another embodiment in which the device is fixed, and by fixing a parallel spring 3 shown in FIG. 3 to the left end of the objective lens holder, the overall length of the device can be reduced. The parallel spring in this case has a window in the center of the spring to prevent collision with the objective lens and the yoke, as shown in FIG. 3, but the invention is not limited to this, and two pairs of parallel springs may also be used.

In the embodiments described above, since the rotor component acting on the oT braking section is proportional to the distance between the center of gravity and the driving point, it is necessary to reduce this distance as much as possible.
7. Resonance phenomena other than the desired translational movement and rotational movement of the moving parts can be suppressed as much as possible.

〔Effect of the invention〕

As explained above, this invention uses a balancer in the objective lens holder. With the simple structure of attaching the lens, harmful resonance phenomena can be suppressed and accurate focus control and tracking control can be achieved.

[Brief explanation of drawings]

FIG. 1A is a top view of an optical information recording/reproducing apparatus according to the present invention, FIG. 1B is a sectional side view, FIG. 2 is a top view of a conventional device, and FIG. The top view and FIG. 4 are explanatory diagrams for explaining the track coil metal. 1... Objective lens, 2... Objective lens holder, 6
...Parallel spring, 4...Shaft, 5...Bearing,
6... Focus coil, 7... Trunk coil, 8... Balancer, 9... Magnet, 10.
・・Yoke, 13-Focus spring support stand, 14・
・Board, that's all.

Claims (1)

[Claims] In an optical information recording/reproducing device that optically reads information on a recording surface of a recording medium or records desired information on the recording surface of a recording medium, light from a light source is focused to form a light spot on the recording surface. an objective lens for condensing light; a parallel spring that supports the objective lens so that it can move in parallel in the optical axis direction of the optical spot; and a rotational movement of the objective lens in a direction perpendicular to the optical axis of the optical spot via the parallel spring. an objective lens holder for holding the objective lens; a first coil for driving the objective lens in the direction of the optical axis of the light spot; and a first coil for driving the objective lens in a direction perpendicular to the optical axis. two coils, the objective lens, the objective lens holder, and the first coil at or near the driving point of the first coil;
and an optical information recording/reproducing device, in which a balancer is attached to the objective lens holder to align the center of gravity with the second coil.