JPH0684182A - Method for detecting actuator displacement - Google Patents

Abstract

PURPOSE:To eliminate the need for a light source for detecting displacement by using an optical fiber as a means for detecting the displacement of an objective lens actuator, and using the flux of light of an optical system as a light source. CONSTITUTION:The movable part of a lens actuator 2 where an objective lens 1 is mounted is provided with a focus coil 6 and a track coil 7 for following the face swing and eccentricity of a recording medium 3 and drives the objective lens 1 with current operation with a magnetic circuit 8. An edge part 11 of an optical fiber 10 is fixed to the lower surface of an actuator movable part 9, the other edge part 12 is led from a light path 13 of an optical block 4, and a light reception element 15 which is divided into two parts is laid out on the extension of irradiation light from the optical fiber edge part 11 of the movable part 9 and on an actuator fixing part 14. An optical light path is divided by a beam splitter 16 at the optical fiber edge part 12 at the optical system side and the flux of light is laid out and fixed at the focal point position which is focused by a focusing lens 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator displacement detecting method used in an optical disk recording / reproducing apparatus for recording information on a rotating flat disk or reproducing already recorded information.

[0002]

2. Description of the Related Art As a device for optically recording information on a concentric or spiral track formed on a rotating disc, or for optically reading and reproducing already recorded information, Devices such as compact discs and optical video discs that record in the form of pits, irradiate it with a light beam, and use the interference of light to reproduce, or magneto-optical discs that record and reproduce using the magneto-optical effect, It has already been put to practical use.

As shown in FIGS. 6 to 10, a conventional example of an actuator displacement detecting method in these devices is a lens actuator 2 equipped with an objective lens 1 which can be driven in a focus direction and a track direction, and a reading light to the lens actuator 2. And an optical block 4 having an optical system for detecting the reflected light from the recording medium 3 are integrally fixed to the carriage 5.

The reading light emitted from the objective lens 1 is reflected by the recording surface of the recording medium 3, passes through the objective lens 1 again, and returns to the detecting portion of the optical block 4, where an error signal is detected and read data is reproduced. Be seen.

The movable part of the lens actuator 2 on which the objective lens 1 is mounted is provided with a focus coil 6 and a track coil 7 to follow the surface wobbling and eccentricity of the recording medium 3, and an electromagnetic circuit with a magnetic circuit 8 is provided. The objective lens 1 is driven by the action.

A pair of left and right photocouplers 53 having a light emitting portion 51 and a light receiving portion 52 are fixed to the actuator fixing portion 14, and the detection light 54 is arranged at a position to be blocked, and the actuator movable portion 9 is provided with a light shielding portion 55. It is attached.

The same track on the recording medium 3 is continuously traced, or the inertia of the objective lens 1 during access
When the actuator moves toward one side, the light shielding portion 55 of the actuator movable portion 9 also moves together with the movable portion 9, so that the light shielding portion 55
The amount of the light flux blocked by is changed as shown in FIG. 8 according to the position of the actuator movable portion 9. Therefore, this light receiving unit 5
By detecting the output of 2, the amount of displacement of the objective lens 1 in the track direction can be known.

As described above, when the same track is continuously traced during reproduction or recording and the objective lens 1 approaches one side, the positioner coil 18 drives the carriage 5 to move the objective lens 1 to the neutral position. Return control is performed.

When reading distant data on the recording medium 3 (at the time of access), the integrated lens actuator 2, optical block 4, and carriage 5 are recorded by the thrust of the positioner coil 18 on the lower surface of the carriage 5. Medium 3
The access operation is realized by moving in the radial direction of.

[0010]

As described above, the displacement detecting means of the conventional lens actuator is composed of the light emitting element, the light receiving element and the light shielding part, and the number of parts is large, and the space occupied by the detecting part in the miniaturized actuator is increased. The proportion was large.

[0011]

In order to solve the above problems, according to the present invention, a lens actuator having at least an objective lens and an end portion fixed to a lens actuator movable portion and the other end fixed to an optical block. Provided is an actuator displacement detection method characterized in that a light flux of an optical system is guided by an optical fiber and is used for displacement detection of an actuator.

[0012]

With the above structure, the deviation from the neutral position of the objective lens can be detected by changing the light-shielding area of the detecting portion and changing the amount of light incident on the light receiving portion.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described in detail with reference to FIGS. First, FIG. 1 is a plan view showing an actuator displacement detecting method of the present invention, FIG. 2 is a front view of the same, and FIG. 3 is an enlarged view showing the main detecting portion. FIG. 4 is a plan view showing the overall structure of an optical head adopting the actuator displacement detection method of the present invention, and FIG. 5 is a front view.

Since the basic operation of the entire optical head is the same as that of the conventional example, its explanation is omitted. A lens actuator 2 provided with an objective lens 1 that can be driven in the focus and track directions, and an optical block 4 having an optical system for making the reading light incident on the lens actuator 2 and detecting the reflected light from the recording medium 3 are integrated. And is fixed to the carriage 5.

The movable portion of the lens actuator 2 on which the objective lens 1 is mounted is provided with a focus coil 6 and a track coil 7 for following the surface wobbling and eccentricity of the recording medium 3, and an electromagnetic action with the magnetic circuit 8 is provided. The objective lens 1 is driven by.

The end portion 11 of the optical fiber 10 is fixed to the lower surface of the actuator movable portion 9 as shown in FIG. 2, and the other end portion 12 is guided from the optical path 13 of the optical block 4, and the optical fiber of the movable portion 9 is fixed. The light receiving element 15 is divided into two parts on the extension of the light emitted from the end part 11 and on the actuator fixing part 14.
To place. The optical fiber end 12 on the optical system side has the optical path of the optical system divided by a beam splitter 16, and the light flux is arranged and fixed at a focal position focused by a focusing lens 17.

The same track on the recording medium 3 is continuously traced, or due to the inertia of the objective lens 1 during access.
When is shifted to one side, the emitted light from the optical fiber end portion 11 of the actuator movable portion 9 is also swung to the left and right as shown in FIG. 3, so that the ratio of the amount of incident light to the two light receiving elements 15 is changed. To do. By detecting the output of the light receiving element 15, the amount of displacement of the objective lens 1 in the track direction can be known.

[0018]

According to the above invention, since the light beam of the optical system is used as the light source by using the optical fiber as the displacement detecting means of the objective lens actuator, the light source for the displacement detection becomes unnecessary. Further, the displacement expansion effect due to the optical path length enables optical-accurate displacement detection with one detection light.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of a displacement detection method of the present invention.

FIG. 2 is a front view of the displacement detection method of FIG.

FIG. 3 is an enlarged view of a detection unit of the displacement detection method of FIG.

FIG. 4 is a plan view showing the overall configuration of an optical head that employs the displacement detection method of FIG.

5 is a front view of the optical head of FIG.

FIG. 6 is a plan view showing a conventional displacement detection method.

7 is a front view of the displacement detection method of FIG.

8 is an enlarged view showing a detection unit of the displacement detection method of FIG.

9 is a plan view showing the overall configuration of an optical head that employs the displacement detection method of FIG.

10 is a front view of the optical head of FIG.

[Explanation of symbols]

 1 Objective Lens 2 Lens Actuator 3 Recording Medium 4 Optical Block 5 Carriage 6 Focus Coil 7 Track Coil 8 Magnetic Circuit 9 Actuator Moving Part 10 Optical Fiber 11 Optical Fiber End (Movable Side) 12 Optical Fiber End (Fixed Side) 13 Optical Path 14 Actuator fixing part 15 Light receiving element 16 Beam splitter 17 Focusing lens 18 Positioner coil 51 Light emitting part 52 Light receiving part 53 Photocoupler 54 Detection light 55 Light blocking part

Claims (1)

[Claims] 1. An objective lens that converges and irradiates a light beam on at least a recording medium, an optical element means that irradiates or does not irradiate the light beam on the objective lens, a lens actuator movable section to which the objective lens is attached, and this actuator movable. An actuator fixing part having a movable part in an arbitrary direction, an optical fiber having one end attached to the lens actuator moving part and the other end optically connected to an optical element means, and the lens actuator fixing part. And a plurality of light receiving elements for receiving light emitted from one end of the fiber, the actuator displacement detecting method.