JPS61134938A - Actuator - Google Patents

Abstract

PURPOSE:To stabilize the motion of an object lens holder in a track direction remarkably by providing the object lens holder with a magnetic body which holds the neutral position by a magnetic force. CONSTITUTION:A magnetic circuit 21 is fixed to a floor board 20, and the coil part of an object lens holder 12 is arranged in the gap part of the magnetic circuit 21, and the magnet 22 of the magnetic circuit 21 is magnetized in a thickness direction. A small iron piece 23 is placed in the center of a track coil 14 and in the object lens holder 12. when an electric current is flowed to the track coil 14, a driving force is generated in the track direction by a magnetic flux generated by the magnetic circuit 21, and the driving force is transmitted to the object lens holder 12, and it is rotated and moved back and moved back and forth with a shaft 17 as the center. A force which pulls back the object lens holder 12 to the center is generated by the attraction between the small iron piece 23 provided in the gap of the magnetic circuit 21 and the magnet 22, and this force acts as the neutral position holding force.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an actuator for an optical pickup. More specifically, it relates to a method for driving an objective lens and a method for maintaining a neutral point.

[Prior art]

Conventionally, the method of driving the objective lens in an actuator that has a structure of deflecting the objective lens in the focus direction and the tracking direction is as shown in Fig. 2, in which the objective lens 1 is held by the objective lens holder 2, and the objective lens holder 2 is The other end of the focus spring 8 is supported by a focus spring 8 shaped like a leaf spring.

The spring holder 4 is fixed to a spring holder 4, and the spring holder 4 is arranged in a direction inclined by 90 degrees from the focus spring 8 so that the objective lens holder 2 can move in parallel in the track direction. It was common for the track springs 6 to be fixed to the floor plate 6.

[Problem that the invention seeks to solve]

However, in the case of this method, there is no particular problem with driving in the focus direction, but when driving in the track direction, the excitation point is the objective lens holder 2, so the deflection force to the track spring 5 is Since the transmission is transmitted via the focus spring 8, a resonance mode in the width direction of the focus spring 8 occurs, and not only does high-order resonance occur, but also the track spring 5
However, it has the disadvantage that buckling phenomenon tends to occur easily.

Therefore, in order to solve these conventional drawbacks, this invention aims to provide an actuator with a structure that does not cause high-order resonance even when it is vibrated and can easily maintain a neutral point. .

[Means for solving problems]

In order to solve the above-mentioned problems, this invention uses a plate spring in the focus direction and a shaft and a bearing in the track direction to make rotational motion less likely to occur, and uses an objective lens holder to control the magnetic circuit. By providing a magnetic material in the part located in the gap, the neutral point is maintained.

[Effect]

In the actuator configured as described above, since the track direction is a rotational motion, parallel motion l occurs, whereas resonance mode in the width direction of the focus spring is extremely unlikely to occur. A buckling phenomenon does not occur, and therefore, higher-order resonance is small and less likely to occur.

In addition, simply by providing a magnetic material in the part of the objective lens holder located in the gap of the magnetic circuit, it is possible to generate a neutral point holding force according to the amount of displacement from the center when the objective lens holder moves in the track direction. be.

〔Example〕

The structure of a preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side cutaway view of the actuator according to the present invention, and FIG. 8 is a plan view of the actuator according to the present invention. The objective lens 11 is held in an objective lens holder 12. A focus coil 18 is wound around the objective lens holder 12 in the plan view of FIG. 2, and two track coils 14 are attached to one side of the objective lens holder 12. Further, a focus spring 16 in the form of a parallel leaf spring is fixed, which vertically sandwiches the side surface of the objective lens holder opposite to the surface to which the track coil 14 is attached.
61ζ is fixed.

The spring holder 16 is configured to deflect the objective lens 11.
A shaft 17 is provided parallel to the optical axis. The one designated by numeral 18 is a bearing holder, and the bearing 1 is made of artificial jewels at the top and bottom.
9 rotatably supports the shaft 17.

What is indicated by the reference numeral 20 is a floor plate, to which the bearing holder 18 is fixed. I and the reference numeral 21 indicate a magnetic circuit which is fixed to the floor plate 20, and the coil portion of the objective lens holder 12 is placed in the gap of the magnetic circuit 21. Reference numeral 22 denotes a magnet of the magnetic circuit 21, which is magnetized in the thickness direction. The sign holder 8 is a small piece of iron located in the center of the track coil 14 in the gap of the magnetic circuit 21 and attached to the objective lens holder 12.

FIG. 4 shows another embodiment of the invention. A ball bearing 24 is used instead of the artificial jewel of the bearing 19. Figure 1jIJb is its plan view.

6 and 7 show another embodiment of the invention. This is a case where two magnetic circuits are used, and FIG. 3116 is a plan view, and FIG. 7 is a side sectional view.

The present invention has the above structure, and the operation of the present invention will be explained below with reference to the drawings. First, the focus direction will be explained. When a current flows through the focus coil 18, a driving force is generated in the vertical direction due to the magnetic flux generated by the magnetic circuit 21. The driving force is transmitted to the objective lens holder 12, which vibrates up and down while being supported by the focus spring 15. Since the focus spring 16 is composed of an upper and lower set of parallel plate springs, the objective lens 11 is aligned with the optical axis from the optical system! It can vibrate in the same direction.

Next, the track direction will be explained. When a current flows through the track coil 14, the magnetic flux t generated by the magnetic circuit 21 generates a driving force in the track direction.

The driving force is transmitted to the objective lens holder 12, which rotates and reciprocates about the shaft 17.

Furthermore, since the bearing 19 is made of artificial jewelry, it can rotate with less friction. Since the bearing 24 is made of a ball bearing, it can rotate with less friction like artificial jewelry. In particular, artificial jewelry has excellent wear resistance, so it has high reliability during long-term use. It also has characteristics.

The force generated by the attractive force between the small piece of iron provided in the gap of the magnetic circuit and the magnet acts as a force to maintain the neutral point.

Further, FIG. 8 and FIG. 9 show another embodiment of the present invention. Similarly, when the support shaft δ side is fixed and the objective lens holder 12 rotates around the support shaft 5 to perform tracking adjustment, the neutral point holding force can be easily adjusted by attaching a small piece of iron as a magnetic material. can be obtained.

〔Effect of the invention〕

Since this invention has the more detailed structure and operation described above, in other words, it has a structure in which the objective lens 11 is deflected in the focus direction by a parallel leaf spring and deflected in the track direction about the rotation axis. As a result, the movement in the track direction is very stable, and the objective lens does not tilt during track deviation, so high-order resonance does not occur, resulting in extremely high performance as an actuator. . In addition, by arranging artificial jewels and ball bearings in the bearing part, there is almost no friction and stable control characteristics can be obtained. Moreover, by simply attaching a small magnetic piece 28 to the objective lens holder 12, it is possible to generate a force for holding the neutral point.

[Brief explanation of drawings]

Figures 1 and 9: Side sectional view according to the present invention Figure 2: Plan view according to the conventional example Figure 8 d: Plan view according to the present invention Figure 1ir4: Side sectional view of another embodiment according to the present invention Figure 6 Figure 6: Plan view of another embodiment according to the present invention. Plan view # of another embodiment according to the present invention! Figure 7: Side cross-sectional view of another embodiment according to the present invention Figure 8: Plan view of another embodiment according to the present invention Figure 9ee Cross-sectional view of another embodiment according to the present invention 1: Objective lens 2 ... Objective lens holder 3 - Focus spring 4 - Spring holder 5 - Track spring 11 - Objective lens 12 - Objective lens holder 15 - Focus spring 16 - Spring holder 17 -@Good shaft 18 skewer - Bearing holder 19... Bearing 21 - Magnetic circuit n... Small iron leg - 1 Ball bearing δ... - Support shaft. Applicant: Seiko Electronic Industries Co., Ltd. Figure 1 Figure 2 Figure 4 Figure 5 Figure 6 @ Figure 7 Figure 8 Figure 9 Cross section AA'

Claims (1)

[Claims] (1) In an actuator having an objective lens, an objective lens holder that holds the objective lens, and a magnetic circuit that generates rotational force in the tracking direction about the objective lens around a support axis, a neutral point is applied to the objective lens holder by magnetic force. An actuator characterized by being provided with a magnetic material for holding.