JPH0877568A - Tilt adjusting device for optical head - Google Patents

Abstract

PURPOSE: To obtain coincidence of a driving point, a centroid and a center of figure with good accuracy by adjusting the driving point, the centroid and the center of figure after assembly. CONSTITUTION: A bobbin 1, a focus coil 2, a tracking coil 3 and an optical system, etc., are supported as a movable element by leaf springs 4a and 4b, and a magnet 5 is provided on a base 6, so that focus and tracking control is performed by supplying a control current to the focus coil 2 and the tracking coil 3. At the time of this control, a tilt is measured, and based on this measuring result, the leaf springs 4a and 4b or balancers 7a and 7b are adjusted by a laser device 11 for additional work in order to diminish the tilt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tilt adjusting device for an optical head.

[0002]

2. Description of the Related Art In an actuator of an optical head, an inclination of an optical axis which occurs with the movement of a bobbin in a focus direction and a tracking direction is suppressed. As a method of suppressing the optical axis, the driving point for moving the movable portion, the center of gravity of the movable portion, and the centroid of the support portion that elastically supports the movable portion are matched. In the conventional optical head, the driving point, the center of gravity,
The position of the centroid is managed by the accuracy of parts and the accuracy of assembly.

[0003]

In the conventional optical head,
Since the positions of the driving point, the center of gravity, and the center of gravity are controlled by the component precision and the assembly precision, there is a problem that the precision control of each component is strict and expensive. In addition, in an actuator of an optical head that performs high-density recording and reproduction, the tilt of the optical axis that occurs with the movement of the bobbin is more severely limited, so that the drive point, the center of gravity, and the center of gravity can be determined only by the accuracy of parts and assembly. There was a problem that it was difficult to manage the position.

Therefore, according to the present invention, after the assembly, the driving point,
An object of the present invention is to provide a tilt adjusting device for an optical head, which is capable of adjusting the center of gravity and the center of gravity so that the driving point and the center of gravity and the center of gravity are accurately matched.

[0005]

According to the present invention, an additional process is carried out by a laser on a movable part and a part of a supporting part of an assembled optical head so that a driving point, a center of gravity and a centroid coincide with each other. It is a thing.

[0006]

By the above means, the drive point and the center of gravity after assembly,
The centroid is adjusted, and the accuracy of individual parts and the accuracy of assembly can be eased. Further, since the tilt of the optical axis is suppressed by the adjustment, it is possible to realize an optical head for high density recording and reproducing.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an optical head device for explaining an embodiment of the present invention and shows a part of an adjusting device. FIG. 2 shows a method of measuring the displacement between the driving point and the centroid, and a method of adjusting the centroid. 3 and 4 show a method of measuring the displacement between the driving point and the center of gravity, FIG. 5 (A) is a method of adjusting the center of gravity, and FIGS. 5 (B) and 5 (C) are other methods of adjusting the center of gravity and the center of gravity. Shows an example of.

First, the structure of the optical head device 12 will be described with reference to FIG. Objective lens (not shown), focus coil 2, tracking coil 3, and balancer 7a,
7b is attached to the bobbin 1, and these constitute the mover. The mover is arranged between the leaf springs 4a and 4b arranged so as to face each other on the left and right.
It is elastically supported by the free end of b. Leaf spring 4
The base portions of a and 4b are fixed to the base 6. In the leaf springs 4a and 4b, the mover has an arrow aa direction (focus direction) in the drawing and an arrow bb direction (tracking direction) in the drawing.
Allowing it to vibrate. The base 6 has a magnet 5 facing the mover. Here, the focus coil 2
When a control current is applied to the tracking coil 3 and the bobbin, the bobbin can be controlled to move in the focus direction and the tracking direction by an electromagnetic force. The control current is given via the actuator amplifier 9. Here, one amplifier is shown as a representative.

In the above optical head device, when the bobbin 1 is controlled to move in the arrow aa direction (focusing direction) and the arrow bb direction (tracking direction) in the figure, the displacement of its moving axis does not occur. preferable. Therefore, tilt adjustment is performed.

The tilt adjustment will be described. A mirror 8 for tilt measurement is attached to the bobbin 1 of the optical head device. A tilt sensor 10 is arranged above the mirror 8. The tilt sensor 10 is a tilt measuring laser 1
3 is output to irradiate the mirror 8. At the same time, mirror 8
The position of the reflected light reflected from is detected. This makes it possible to measure the tilt of the bobbin.

Next to the tilt measurement, a processing laser device 11 is provided to perform tilt adjustment. This processing laser device 11 cuts a part of a bobbin or a leaf spring,
It can be processed and its center of gravity and centroid can be adjusted.

Next, a method of adjusting the centroid of the optical head device and the driving point will be described. In FIG. 2, the centroid of the support system of the mover is shown by a triangle, and the driving point is shown by a cross mark. When adjusting the centroid and the driving point, a direct current is applied to the focus coil 2 by the actuator amplifier 9. Here, as shown in (a) of FIG. 2A, when the centroid is in the Y direction with respect to the driving point (see (c) of FIG. 2A), the bobbin 1
A driving force for driving the Z direction in the Z direction generates a torsion moment in the negative direction around the X axis. As a result, a tilt as shown in (b) of FIG. That is, bobbin 1
The axis of is tilted in the negative direction around the X axis. For this reason, the tilt measuring laser 13 output from the tilt sensor 10 is reflected at an angle by the mirror 8 and the bobbin 1
The tilt of can be detected.

In the case of this example, a negative rotation about the X-axis is generated by the driving force in the Z-axis direction, so that the spring constant of the leaf spring 4a is larger than the spring constant of the leaf spring 4b. It can be understood that the drive point is deviated. Therefore, in order to eliminate this deviation, as shown in FIG. 2B, a part of the leaf spring 4a is cut by the processing laser device 11 to reduce the spring constant, so that the centroid matches the driving point. Make adjustments as necessary. Similarly, the tracking direction is also adjusted.

Next, a method of adjusting the center of gravity and the driving point of the mover of the optical head device will be described with reference to FIGS. 3, 4 and 5. In FIG. 4, the center of gravity of the mover of the optical head device is indicated by a circle, and the driving point is indicated by a cross. When adjusting the center of gravity and the drive point, an alternating drive current is supplied to the focus coil 2 by the actuator amplifier 9 as shown in FIG. Here, as shown in FIG. 4A, when the center of gravity is deviated from the driving point, torque is generated by the driving force, and dynamic torque as shown in FIGS. 4B and 4C is generated. Tilt occurs. For this reason, the tilt measuring laser 13 output from the tilt sensor 10 is reflected by the mirror 8 at an angle, and as a result, a detection signal including a dynamic tilt of the bobbin 1 is obtained, as shown in FIG. Here, the positional deviation between the driving point and the center of gravity can be confirmed by paying attention to the phase delay between the driving current and the detection signal of the dynamic tilt. Since this phase delay (deviation) information represents the positional deviation between the driving point and the center of gravity, for example, as shown in FIG. 5 (A), the processing laser device 11 cuts a part of the bunlancers 7a, 7b. The center of gravity can be adjusted by processing. Similarly, the tracking direction is also adjusted.

In the above description, the method of adjusting the centroid and the center of gravity of the mover of the optical head device by cutting the leaf springs 4a and 4b and cutting the baluners 7a and 7b attached to the bobbin has been described. However, not limited to this, FIG.
As shown in (B) and (C), there is also a method in which the excimer laser 14 is used to remove the leaf springs 4a and 4b and a part of the bobbin 1 to adjust the centroid and the center of gravity. In this case, the van balancers 7a and 7b shown in the previous embodiment can be omitted. Further, since there is no burr during processing, the centroid can be adjusted without deteriorating the characteristics of the supporting means.

[0016]

As described above, according to the present invention,
After the optical head device is assembled, the center of gravity and the center of gravity can be adjusted to suppress unnecessary tilting of the optical axis due to the driving of the bobbin 1. Therefore, the accuracy of individual parts and the accuracy of assembly can be relaxed and the cost can be effectively reduced, and an optical head device for high-density recording and reproducing can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram of an optical head device shown for explaining an embodiment of the invention.

FIG. 2 is a diagram shown for explaining a tilt adjustment principle of the apparatus of FIG.

FIG. 3 is an explanatory view of a principle of measuring a dynamic tilt of the apparatus of FIG.

FIG. 4 is an explanatory view of a principle of measuring a dynamic tilt of the apparatus of FIG.

FIG. 5 is an explanatory diagram of an additional process used in the present invention.

[Explanation of symbols]

1 ... Bobbin, 2 ... Focus coil, 3 ... Tracking coil, 4a, 4b ... Leaf spring, 5 ... Magnet, 6 ... Base,
7a, 7b ... Bang balancer, 8 ... Mirror, 10 ... Tilt sensor, 11 ... Processing laser device, 12 ... Optical head device,
13 ... Tilt measuring laser.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunio Noguchi 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Stock company Toshiba Multimedia Technology Laboratory

Claims (5)

[Claims] 1. A holder for holding at least an optical system and a coil for an optical head, a support for elastically supporting the holder in at least a focus direction or a tracking direction, and a holder for at least the focus direction or a tracking direction. Driving means for driving in a direction, a measuring means for measuring a tilt caused by a positional deviation between a centroid of the support and a driving point of the driving means when the holding body is driven, and a measuring means of the measuring means. A tilt adjusting device for an optical head, comprising: a laser device for additional machining for performing additional machining of the holding means so as to reduce the tilt based on a measurement result. 2. The tilt adjusting device for an optical head according to claim 1, wherein the additional machining adjusts the centroid by evaporating or removing a part of the support. 3. A holder for holding at least an optical system and a coil for an optical head, a holder for elastically supporting the holder in at least the focus direction or the tracking direction, and a holder for at least the focus direction or the tracking direction. Driving means for driving in the direction, measuring means for measuring a tilt caused by displacement of the center of gravity of the holding body and a driving point of the driving means when the holding body is driven, and measurement by the measuring means A tilt adjusting device for an optical head, comprising: a laser device for additional machining for performing additional machining of the holding means so as to reduce the tilt based on the result. 4. The tilt adjusting device for an optical head according to claim 3, wherein the additional machining adjusts the center of gravity by evaporating or removing a part of the holding body. 5. The optical head according to claim 3, wherein in the additional machining, the center of gravity is adjusted by cutting, deforming or altering a part of the balancer attached integrally with the holder. Tilt adjustment device.