JP2760366B2 - Optical information recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus. INDUSTRIAL APPLICABILITY The present invention is suitably applied to, for example, an optical information recording / reproducing apparatus having a separation type head that performs tracking in a low frequency region by a linear motor and performs tracking in a high frequency region by a galvanometer mirror.

[0002]

2. Description of the Related Art In an optical information recording / reproducing apparatus such as an optical disk apparatus, focusing and tracking are performed by moving a movable portion including an objective lens in an optical head by an actuator. The optical head includes a separation type head in which an actuator section separates from a laser light source section and moves in a radial direction of a disk, and an integrated head in which an actuator section moves integrally with the laser light source section in a radial direction of a disk. There is. The separation type head is advantageous in increasing the speed of the seek operation because the movable portion is easily lightened and a large acceleration is easily obtained. In order to further reduce the weight of the movable part, a separation type head is known which performs tracking in a low frequency region by a linear motor and performs tracking in a high frequency region by a galvanometer mirror.

[0003]

In the prior art which performs the galvanomirror type fine tracking, the laser beam is obliquely incident on the objective lens in accordance with the rotation angle of the oscillation of the galvanomirror. This causes an offset in the tracking signal. Also, if the galvanomirror deviates from the neutral position due to vibration, it becomes difficult to perform track counting during seek. Therefore, it is required to detect the rotation angle of the galvanomirror in order to perform offset correction of the tracking signal and to maintain the neutral position of the galvanomirror. However, it is very difficult to detect the rotation angle because the rotation angle is at most several minutes.

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide an optical information recording / reproducing apparatus having an optical head capable of obtaining a high galvanomirror rotation angle detection accuracy even with a small size. Is what you do.

[0005]

According to the present invention, there is provided an optical information recording / reproducing apparatus having an optical head for performing a tracking operation using a galvanomirror. An auxiliary mirror is disposed, and the rotation angle of the galvanomirror is detected by detecting the light beam from the light source after being repeatedly reflected by the galvanomirror and the auxiliary mirror a plurality of times. Information recording and reproducing apparatus.

[0006]

A large optical path is secured by a plurality of repetitive reflections by the galvanometer mirror and the auxiliary mirror, and the rotation angle of the galvanometer mirror is converted into a large displacement for measurement.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially cutaway perspective view for explaining the configuration of an embodiment of an optical information recording / reproducing apparatus according to the present invention, and FIG. 2 is a partial plan view showing a linear motor section of the optical head. FIG. 3, FIG. 4, and FIG. 5 are a sectional view taken along line AA, a sectional view taken along line BB, and a sectional view taken along line CC of FIG. 2, respectively.

In these figures, an objective lens 6 is held by a holder 4, and a focus coil 5 is attached to the holder. The objective lens holder 4 is attached to the carriage 1 by a parallel leaf spring 3 so as to be able to move in parallel in a substantially focusing direction. The carriage 1
Is fitted with a seek coil 2. Carriage 1
Are supported by two rod-shaped inner yokes 7 arranged in parallel so as to be slidable in the longitudinal direction of the yoke. Each inner yoke 7 constitutes a magnetic circuit together with the relay yoke 13, the outer yoke 9 and the magnet 8. The two inner yokes are positioned by spacers 11 and 12, and this positioning is performed by a pressing force of a leaf spring 10 disposed between the base 15 and the outer yoke 9. The leaf spring is fixed to the base 15 by screws 16 after the inner yoke is positioned by the pressing force. Thus, the magnetic circuit is fixed to the base 15. The spacers 11 and 12 are both in the shape of a round bar,
It is possible to provide high outer diameter accuracy, and the inner yoke 7
Can be maintained with high precision. The spacer 11 is provided at the center with a hole through which a recording or reproducing laser beam passes.

[0010] As shown in FIG.
The laser light emitted from the laser beam passes through a prism 18 and is shaped by a beam. Then, the laser beam is reflected by a galvanomirror 17, passes through a hole in the spacer 11, and is raised by a flip-up mirror 14 attached to the carriage 1. (FIG. 3
), The optical path is bent upward, passes through the objective lens 6, and irradiates a spot on an optical disc (not shown). The laser beam reflected by the optical disk returns along the same path to the prism 18 where it is reflected by the prism toward the condenser lens 20 and split into three optical paths by the prism 22 via the mirror 21. And reaches the sensor 23. Reference numeral 24 denotes a spindle motor for rotating the optical disk.

Here, it is important that the optical path of the laser beam and the movement trajectory of the carriage 1 be parallel.
In this embodiment, since the inner yoke 7 also serves as a sliding guide, the mounting surface of the inner yoke 7 on the base 15 and the prism 1
The mounting surface of the optical members such as 8, 23 and the like on the base 15 can be configured as the same surface, so that the positioning can be performed with high accuracy.

FIG. 6 is a perspective view showing the structure of the driving means for the galvanometer mirror 17. As shown in FIG. The galvanomirror is fixed to a leaf spring 31 and both ends of the leaf spring are connected to the base 15.
It is fixed to. Accordingly, the galvanomirror 17 can swing in the direction of the arrow. A coil 35 is attached to the galvanomirror 17. On the other hand, a yoke 32 is fixed to the base 15, and a holder 33 is attached to the yoke.
The magnet 34 is attached via the. The magnet, the magnet holder 33 and the yoke 32 form a magnetic circuit. When the coil 35 is energized, a magnetic field generated in two gaps between the magnet 34 and the upper and lower ends of the yoke 32 is generated by the coil 35.
Is crossed in opposite directions in the upper and lower gaps, so that the galvanomirror 17 is swung in the direction of the arrow by the force acting on the coil 35.

FIG. 7 is a perspective view showing a configuration for detecting the rotation angle of the galvanometer mirror 17. As shown in FIG. An auxiliary mirror 36 is fixed to the base 15 so as to face the galvanometer mirror 17. Further, a light emitting element 37, a lens 38, and a detection element 39 such as a PSD are arranged. In addition, L-
L is an optical path of the recording or reproducing laser beam.

The light emitted from the light emitting element 37 and passing through the lens 38 is reflected by the galvanomirror 17 and the auxiliary mirror 3.
6 after being repeatedly reflected by the detecting element 3
Reach 9 Even if the galvanomirror 17 swings in the direction of the arrow shown in FIG. 6, the horizontal positional relationship is unchanged, so that the horizontal light incident position on the detection element 39 is determined by the rotation angle of the swing of the galvanomirror 17. It is constant regardless of However, the vertical incident position on the detecting element 39 changes according to the rotation angle of the galvanometer mirror 17, and when the galvanomirror 17 rotates upward, light enters above the detecting element 39 and swings downward. Then, light enters below the detection element 39. FIG. 8 shows how the displacement is amplified by repeated reflection.

FIG. 8 is a view as viewed in the direction A of FIG. 7, and is a view in which the galvanomirror 17 and the auxiliary mirror 36 which are opposed to each other are viewed horizontally from the side. After the light projected from the light emitting element 37 passes through the lens 38, it is reflected by the galvanomirror 17 inclined at an angle θ by an angle 2θ. After that, each time the auxiliary mirror 36 and the galvanometer mirror 17 are reflected, the inclination angle is increased, and the displacement is amplified to a sufficiently detectable displacement amount and is incident on the detection element 39.

In this embodiment, the reflection surface of the recording or reproduction laser beam of the galvanometer mirror 17 is used for detecting the rotation angle of the galvanometer mirror. Alternatively, a reflection surface for detecting a rotation angle can be formed.

Next, the tracking and focusing operations will be described. When current is applied to the seek coil 2 via a flexible cable (not shown), a current flows in a direction orthogonal to a horizontal magnetic field generated by a magnetic circuit including the inner yoke 7, the magnet 8, the outer yoke 9, and the relay yoke 13. The seek coil 2 receives a longitudinal force of the inner yoke 7 to drive the carriage 1 (coarse tracking). At the same time, fine tracking is performed by the swing of the galvanometer mirror 17, and the rotation angle of the galvanometer mirror is detected as described above,
Offset correction is performed. At this time, the carriage 1
Is slid in a state in which the protrusions 1a, 1b, 1c, and 1d are brought into contact with the inner yoke 7 and guided and guided so that the movement in the horizontal direction is restricted. Is prevented. Then, the carriage wings 1e, 1f, 1g, 1h are guided by the inner yoke 7 to move with their vertical movement being restricted. As shown in FIG. 5, the inner yoke 7 has its upper and lower surfaces cut in a tapered shape, and the carriage 1 abuts the inner yoke 7 at both left and right ends, so that it is easy to maintain the carriage 1 horizontally. Next, when the focus coil 5 is energized, a current flows in a direction orthogonal to the horizontal magnetic field, the focus coil 5 receives a vertical force, and the objective lens portion supported by the parallel leaf spring 3 moves in the vertical direction. Moving.

[0018]

According to the present invention as described above, by securing a large optical path by a plurality of repeated reflections by the galvanometer mirror and the auxiliary mirror, the galvanometer mirror rotation angle can be converted to a large displacement and measured. Thus, a high galvanomirror rotation angle detection accuracy can be obtained even with a small size.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view illustrating the configuration of an embodiment of an optical information recording / reproducing apparatus according to the present invention.

FIG. 2 is a partial plan view showing a linear motor section of the optical head of the embodiment of FIG.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a sectional view taken along line BB of FIG. 2;

FIG. 5 is a sectional view taken along line CC of FIG. 2;

FIG. 6 is a perspective view illustrating a configuration of a driving unit of the galvanomirror.

FIG. 7 is a perspective view showing a configuration for detecting a rotation angle of a galvanomirror.

FIG. 8 is a view as viewed from A in FIG. 7;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Carrier 2 Seek coil 3 Leaf spring 4 Objective lens holder 5 Focus coil 6 Objective lens 7 Inner yoke 8 Magnet 9 Outer yoke 10 Leaf spring 11, 12 Spacer 13 Relay yoke 14, 21 Mirror 15 Base 17 Galvano mirror 18, 22 Prism 19 Laser light source 20 Condenser lens 23 Sensor 24 Spindle motor 31 Leaf spring 32 Yoke 33 Magnet holder 34 Magnet 35 Coil 36 Auxiliary mirror 37 Light emitting element 38 Lens 39 Detection element

Claims (1)

(57) [Claims] 1. An optical information recording / reproducing apparatus having an optical head for performing a tracking operation using a galvanomirror, wherein an auxiliary mirror is arranged opposite to the galvanomirror, and an optical beam from a light source is supplied to the galvanomirror. And an optical information recording / reproducing apparatus, wherein the rotation angle of the galvanometer mirror is detected by detecting the light after being repeatedly reflected by the auxiliary mirror a plurality of times.