JPS61220144A - Optical head lens actuator - Google Patents

Abstract

PURPOSE:To improve the precision of the movement in the tracking direction by forming a rotating arm, which controls the movement in the tracking direction, and a revolving shaft unitedly and inserting the revolving shaft into the bearing to support it. CONSTITUTION:Two through holes are provided on a diagonal in the bottom part of a bearing 14, and revolving shafts 21 formed unitedly with a rotating arm 15 are inserted to through holes, and the bearing 14 is supported by thick root parts of them. The other end of the rotating arm 15 is attached to a yoke 16 of a magnetic circuit rotatably by driven pins 23. Since the rotating arm 15 and revolving shafts 21 are formed unitedly backlash of the attaching part is not generated. The clearance between the through hole and the revolving shaft 21 is controlled to suppress backlash. Thus, the precision of the movement in the tracking direction is improved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an optical head in an optical memory device.
More specifically, it relates to a drive mechanism for an objective lens actuator, which is the tip of an optical head. [Summary of the Invention] The present invention relates to an objective lens actuator for an optical head, in which the movement in the focus direction regards the lens barrel as a piston. The movement in the tracking direction is regulated by the circular movement of two arms having rotation axes at one end, and the movement in the tracking direction is regulated by the circular movement of two arms having rotating shafts at one end. It allows you to perform movements accurately.

[Conventional technology]

Fig. 3 is a perspective view of a conventional example.◎The objective lens 10 is fixed by a lens barrel 11, and a rectangular focusing coil 12 is wound around it. Tracking coil 1
Reference numeral 6 is a bearing 014 arranged and fixed as shown in the figure, which receives the lens barrel, and has a piston-cylinder relationship with the lens barrel. A rotary arm 15 is fixed to the bottom of this bearing at two diagonal points, and the other ends of the arms are fixed to the bottom of the magnetic circuit yokes 16 on opposite sides.

Figure 4 is a view of this from below. This bearing 14
is a rotating arm 15 centered on fulcrums 17 and 17',
Along with the circular movement at 15', it is pushed upward or downward in the figure and moves linearly in the tracking direction. A permanent magnet 18 forms a magnetic circuit together with the yoke 16.

The focus film 12 and the tracking coil 13 are inserted into the gap 19 of this magnetic circuit, and the focus film 12 and the tracking coil 13 are inserted into the gap 19 of the magnetic circuit, and a current s y and a current i! is applied, the direction is perpendicular to the magnetic field H, so according to Lemming's left hand rule, the focusing coil receives the vertical force shown in Figure 2,
Further, each tracking coil moves in response to a force in the front and back direction. On the other hand, since the damper 20 elastically holds these coil groups and the objective lens at a neutral position,
The lens causes motion in two axes perpendicular to the direction regulated by the lens barrel and the bearing, and the direction in which the bearing itself moves. [Problems and objects to be solved by the invention] Lens actuator with the above structure With Eta, linearity in the direction of motion, ie backlash, is a problem. In the focusing direction, highly accurate movement is possible by considering the clearance between the lens barrel and the bearing and the length of sliding. On the other hand, in the tracking direction, it is possible to achieve accurate movement by removing the play in the four mounting points of the rotating arm. However, in order to accurately satisfy the required value, requires high-precision machining parts and high assembly precision. Therefore, the present invention provides a method that reduces the assembly precision required for the rotary arm section by improving the rotary arm in the conventional example, and enables accurate tracking at a lower cost.

[Means for solving problems]

The objective lens actuator according to the present invention is a lens actuator that moves the objective lens in the focusing direction and the tracking direction.The movement in the focusing direction regards the lens barrel as a piston, and uses a cylinder that fits with the lens barrel. The movement in the tracking direction is regulated by a bearing, and the movement in the tracking direction is fixed at two diagonal points on the bottom of the bearing, and the other end is fixed in two opposite directions on the magnetic circuit side. Double circular motion of two rotating arms. The movement of the bearing is regulated by
The rotary arm has a rotary shaft at one end thereof in a direction perpendicular to the arm, and the rotary shaft passes through the bearing and is movably fixed to the bearing, constituting a precise two-axis actuator for tracking motion. [Function] The interlocking play in the tracking direction is caused by the attachment of the two rotating arms.This is due to the long rotating shaft with the fixed end of the bearing fixed at right angles to the arm, and the through hole into which the rotating shaft on the bearing side is inserted. is suppressed by the clearance of

〔Example〕

FIG. 1 is a partial cross-sectional view of the main part of an embodiment of the present invention. Reference numeral 14 denotes a bearing made of a fluororesin material, and has through holes at two diagonal points, into which a rotating shaft 21 integrally formed with the rotating arm 15 is inserted. The base of the rotating shaft is thick, and its upper end supports the bearing. Further, the tip of the rotating shaft is fixed by an E-ring 22, and the rotating shaft itself freely rotates within the bearing. Further, the other end of the arm is fixed by a driving pin 23 at the bottom of the yoke 16, and this portion becomes the center of rotation of the arm. FIG. 2 is a perspective view showing the structure of the rotary arm. Also, the part with a dash in the number in Figure 1 is the other rotating arm part.

〔Effect of the invention〕

In the present actuator having the above configuration, since the rotary arm and the rotary shaft are integrally formed, there will be no looseness when the rotary shaft and the arm portion are attached.

- Play can also be suppressed by controlling the clearance between the bearing's through hole and the rotating shaft.

In the example, the attachment part of the arm and yoke is driven by a bottle, but it goes without saying that if this part also forms a long rotating shaft and is fixed using the same principle, even greater accuracy can be achieved. do not have.

As described above, according to the present invention, the accuracy of linear movement of the objective lens actuator used in the optical head can be improved. In particular, improvements to the rotating arm have further increased the accuracy of tracking movement and simplified the assembly method◎

[Brief explanation of drawings]

Fig. 1 is a side view of an embodiment of the present invention; Fig. 2 is a perspective view of an improved rotating arm; Fig. 6 is a perspective view of a conventional lens actuator;
Fig. 4 is a bottom view of the same. ...Arm mounting bin 18...Magnet 19...Magnetic gap 20...Damper 21...Rotary shaft 22...E ring 23...Mounting bin or more

Claims (1)

[Claims] a) In the objective lens actuator that moves the objective lens in the focusing direction and the tracking direction, b) The movement in the focusing direction is performed by regarding the lens barrel as a piston, and using a cylinder that fits with the piston. c) Movement in the tracking direction is regulated by a double circular motion of two rotary arms fixed at two diagonal points on the bottom surface of the bearing, and the other end is fixed in two opposite directions on the magnetic circuit side. d) and the rotating arm has a rotating shaft at one end in a direction perpendicular to the arm, and the rotating shaft is movably fixed to the bearing by passing through the bearing. An optical head lens actuator characterized by: