JPH11259888A - Deflecting device, and optical information recording and reproducing head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deflecting device which can decrease the rotational quantity of a galvanomirror without narrowing a deflection range. SOLUTION: A deflecting device is equipped with a galvanomirror 26a which is so constituted that its reflecting surface can rotate in a specific direction, and a fixed mirror 26b which is arranged opposite the reflecting surface of the galvanomirror; and luminous flux which is made incident on the galvanomirror 26a is made incident on the fixed mirror 26b at least once and the luminous flux reflected by the fixed mirror is reflected again by the galvanomirror.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflecting device for an optical information recording / reproducing head, and more particularly to a deflecting device for a head for performing fine movement tracking of an optical disk by deflecting a laser beam.

Recently, a magneto-optical disk drive having a surface recording density exceeding 10 Gbit / (inch) ² has been developed. In this apparatus, for example, the incident angle of a laser beam incident on an objective optical system provided at the tip of a coarse movement arm that rotates in a direction intersecting the track of the magneto-optical disk is finely adjusted by a deflecting means such as a galvanometer mirror. , For example, 0.34 μm
It is conceived that accurate tracking can be performed with fine track tracking at a narrow track pitch level. In order to rotate the galvanomirror, it is necessary to secure a sufficient space to allow the rotation. In order to reduce the size of the entire apparatus, it is preferable that the amount of rotation of the galvanomirror is small. For this reason, there has been a demand for a deflecting device that requires a small amount of rotation of the galvanometer mirror during fine movement tracking by deflection.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and has as its object to provide a deflecting device capable of reducing the amount of rotation of a galvanomirror without reducing the deflection range. It is an object.

[0004]

For this purpose, the deflecting device according to the present invention comprises a galvanomirror having a reflecting surface rotatable in a predetermined direction, and a galvanomirror disposed opposite the reflecting surface of the galvanomirror. A light beam incident on the galvano mirror is incident on the fixed mirror at least once, and a light beam reflected by the fixed mirror is reflected again by the galvanomirror. Item 1).

Since the light beam incident on the deflecting device is reflected a plurality of times between the galvanometer mirror and the fixed mirror, the direction of the light beam emitted from the deflecting device is greatly changed even if the amount of rotation of the galvanomirror is small. be able to.

In an optical information recording / reproducing head, a parallel light beam emitted from a laser light source is deflected by a deflecting means, made incident on an objective optical system and condensed on an optical disk, and receiving the reflected light. The deflecting means may be constituted by a deflecting device comprising the above-mentioned galvanomirror and fixed mirror.

Further, in the optical information recording / reproducing head, the reflecting surface of the galvanomirror is arranged so that an incident angle of a parallel light beam incident on the objective optical system is displaced within an incident surface parallel to a tracking direction of the optical disk. It is characterized by being rotatable.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, referring to FIGS.
Recording / reproducing called near field recording (NFR) technology, which has been proposed in response to the demand for external storage devices, especially the demand for large storage capacity accompanying the progress of hardware and software related to computers in recent years. An outline of a magneto-optical disk recording / reproducing apparatus using the method will be described.

FIG. 1 is an overall schematic diagram of an optical disk drive device 1. In the disk drive device 1, an optical disk 2 is mounted on a rotating shaft of a spindle motor (not shown). A rotating (coarse movement) arm 3 for reproducing or recording information on the optical disk 2 is mounted so as to be parallel to the recording surface of the optical disk 2. The rotary arm 3 is rotatable by a voice coil motor 4 in a plane parallel to the optical disk 2 about a rotation axis 5 as a rotation center. A floating optical head 6 having an optical element mounted thereon is mounted on a tip of the rotating arm 3 facing the optical disk 2. A light source module 7 having a light source unit and a light receiving unit is disposed near the rotation shaft 5 of the rotating arm 3, and is configured to be driven integrally with the rotating arm 3.

FIGS. 2 and 3 illustrate the distal end portion of the rotating arm 3, and particularly illustrate the floating optical head 6 in detail. The floating optical head 6 is attached to the flexure beam 8 and is arranged to face the optical disc 2. The flexure beam 8 is fixed to the rotating arm 3 at the other end.
Is pressed in the direction in which the floating optical unit 6 at the distal end is brought into contact with the optical disc 2.

The floating optical unit 6 includes a floating slider 9, an objective lens 10, and a solid immersion lens (S
IL) 11 and a magnetic coil 12 and serve to converge a parallel laser beam 13 emitted from the light source module 7 onto the optical disc 2. A rising mirror 31 is fixed to the tip of the rotating arm 3 to guide the laser beam 13 to the floating optical unit 6. Objective lens 1 by rising mirror 31
The laser light flux 13 incident on 0 is converged by the refraction of the objective lens 10. A solid immersion lens (SIL) 11 is disposed near the light-collecting point.
The convergent light is applied to the optical disc 2 as finer evanescent light 15.

A magnetic coil 12 for recording by a magneto-optical recording method is formed around a solid immersion lens (SIL) 11 facing the optical disk 2. It can be applied on the surface. This evanescent light 1
5 and the magnetic coil 12 enable high-density recording and reproduction on the optical disk 2. The floating optical unit 6 floats by a very small amount due to the airflow generated by the rotation of the optical disk 2 and follows the surface runout of the optical disk 2. For this reason, focus control (focus servo) of the objective lens, which is required in the conventional optical disk device, is not required.

The light source module 7 mounted on the rotating arm 3 and the light beam guided to the floating optical unit 6 will be described in detail below with reference to FIGS. The rotating arm 3 has a floating type optical unit 6 mounted at the tip and a driving coil 1 for driving a voice coil motor 4 at the other end.
6 is fixed. The drive coil 16 is a flat coil, and is inserted and arranged in a magnetic circuit (not shown) with a gap. The rotating shaft 5 and the rotating arm 3 are provided with a bearing 17,
When the current is applied to the drive coil, the rotation arm 3 can be rotated about the rotation shaft 5 by the electromagnetic action with the magnetic circuit.

The light source module 7 mounted on the rotating arm 3 has a semiconductor laser 18, a laser driving circuit 19,
Collimating lens 20, compound prism assay 21, laser power monitor sensor 22, reflection prism 2
3, a data detection sensor 24 and a tracking detection sensor 25 are arranged. The laser beam in a divergent beam state emitted from the semiconductor laser 18 is converted into a parallel beam by the collimating lens 20. The cross-sectional shape of the parallel light beam is an elliptical shape due to the characteristics of the semiconductor laser 18, and it is inconvenient to narrow the light beam onto the optical disk 2 minutely. Therefore, the cross-sectional shape of the parallel light beam is shaped by making the parallel light beam having an elliptical cross section emitted from the collimating lens 20 enter the composite prism assay 21.

The entrance surface 21a of the composite prism assay 21
Has a predetermined slope with respect to the incident optical axis. By refracting the incident light, the cross-sectional shape of the parallel light beam can be shaped from an oval shape to a substantially circular shape. The shaped laser beam travels through the complex prism assay 21 and enters the first half mirror surface 21b. The first half mirror surface 21 b transmits information obtained from the optical disc 2 to the data detection sensor 24 and the tracking detection sensor 25.
However, on the outward path, it serves to separate the light beam to the laser power monitor sensor 22 for detecting the output power of the laser emitted from the semiconductor laser 18.

Since the laser power monitor sensor 22 outputs a current proportional to the intensity of the received light, the output of the semiconductor laser 18 can be stabilized by feeding back this output to a laser power control circuit (not shown). . The laser beam 13 having a substantially circular cross-sectional shape and emitted from the composite prism assay 21 is applied to the deflecting mirror 26, and the traveling direction of the laser beam 13 is changed. The deflecting mirror 26 is attached to a galvano motor 27 having a rotation center about an axis perpendicular to the plane of the paper, and can deflect the laser beam 13 by a small angle in a direction parallel to the plane of the paper.

The galvano motor 27 is provided with a deflection mirror position detection sensor 28 for detecting the rotation angle of the deflection mirror 26. The laser beam 13 reflected by the deflecting mirror 26 is transmitted to the first relay lens 29 and the second relay lens 29.
After passing through a relay lens (imaging lens) 30, the light is reflected by a rising mirror 31 and reaches the floating optical unit 6. The first relay lens 29 and the second relay lens 30 make the relationship between the reflection surface of the deflecting mirror 26 and the pupil surface (principal plane) of the objective lens 10 arranged in the floating optical unit 6 into a conjugate relationship. That is, a relay lens optical system is formed. That is, when the condensed beam on the optical disk 2 is slightly deviated from a predetermined track, the deflecting mirror 26 is slightly rotated to tilt the laser beam 13 incident on the objective lens 10 to move the focal point on the optical disk 2. Correction. However, when performing focus correction with this method,
If the optical distance between the deflecting mirror 26 and the objective lens 10 is long, the amount of movement of the laser beam 13 incident on the objective lens 10 increases, and it may not be possible to enter the objective lens 10.

In order to avoid such a phenomenon, the first relay lens 29 and the second relay lens 30
The relationship between the reflecting surface of the deflecting mirror 26 and the pupil surface of the objective lens 10 is set to be a conjugate relationship. That is, when the deflecting mirror 26 is rotated, the incident angle of the laser beam 13 incident on the objective lens 10 changes, and the optical disc 2
By utilizing the fact that the focused beam moves in the tracking direction, accurate tracking control can be performed. The access operation over the inner circumference / outer circumference of the optical disc 2 is performed by the voice coil motor 4 and the rotating arm 3.
Is rotated, and only minute tracking control is performed by rotating the deflection mirror 26.

The returning laser beam 13 reflected from the optical disk 2 returns in the reverse direction to the forward path and is reflected by the deflecting mirror 2.
The reflected light is incident on the composite prism assay 21.
Thereafter, the light is reflected by the first half mirror surface 21b and travels to the second half mirror surface 21c. The second half mirror surface 21c generates transmitted light directed to the tracking detection sensor 25 and reflected light directed to the data detection sensor 24, and separates the laser beam on the return path. The laser beam transmitted through the second half mirror surface 21c is applied to the tracking detection sensor 25, and outputs a tracking error signal.

On the other hand, the laser beam reflected by the second half mirror surface 21c is polarized and separated by the Wollaston prism 32, is converted into convergent light by the condenser lens 33, is reflected by the reflection prism 23, and is reflected by the data detection sensor. 24. The data detection sensor 24 has two light receiving areas, and receives two polarized beams polarized and separated by the Wollaston prism 32 to read data information recorded on the optical disk 2 and output a data signal. To be precise, the tracking error signal and the data signal are generated by a head amplifier circuit (not shown) and sent to a control circuit or an information processing circuit.

Next, with reference to FIG. 6, the configuration of the deflecting device 26M in which the amount of rotation of the galvanomirror is suppressed to a small value will be described. .

In the configuration shown in FIGS. 4 and 5, when the galvanomirror (deflecting mirror) 26 is rotated by an angle θ from the position shown by the solid line to the position shown by the broken line, as shown in an enlarged view in FIG. The light beam changes its traveling direction by an angle (2 × θ) from the direction shown by the solid line to the direction shown by the broken line.

As shown in FIG. 6, the deflecting device 26M according to the present invention, like the galvanomirror 26, is disposed so as to be rotatable and opposed to the reflecting surface of the galvanomirror 26a. Fixed mirror 26b
And a configuration having: The reflection surface of the fixed mirror 26b faces the reflection surface of the galvanometer mirror 26a.

According to such a configuration, the light beam incident on the galvanomirror 26a is reflected by the reflection surface and then enters the fixed mirror 26b. The light beam reflected by the fixed mirror 26b is reflected by the galvanometer mirror 26a again, and then travels to the objective optical system. That is, the light beam incident on the deflecting device 26M is reflected twice by the rotatable galvanomirror 26a, and then travels to the objective optical system.

For this reason, when the galvanomirror 26a is rotated by an angle θ from the position shown by the solid line to the position shown by the broken line,
The light beam traveling toward the objective optical system changes its traveling direction by an angle (4 × θ) from the direction shown by the solid line to the direction shown by the broken line.

Therefore, the deflecting device 26M having the structure shown in FIG.
Is used in the disk drive device 1 described with reference to FIGS. 1 to 5, the change in the direction of the emitted light beam from the deflecting device 26M can be made larger than the amount of rotation of the galvanomirror. 3 can have a margin.

[0027]

As described above, according to the present invention, it is possible to realize a deflecting device capable of reducing the amount of rotation of the galvanomirror without reducing the deflection range.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a basic configuration of a magneto-optical disk device according to an embodiment.

FIG. 2 is a diagram showing a distal end portion of a rotating arm.

FIG. 3 is a cross-sectional view showing a floating optical unit.

FIG. 4 is a plan view showing a deflection mirror and a floating optical unit.

FIG. 5 is a side sectional view of a rotating arm.

FIG. 6 is a diagram showing a basic configuration of a deflection device according to the present invention.

FIG. 7 is an enlarged view showing a basic configuration of the deflection mirror shown in FIG.

[Explanation of symbols]

2 Optical Disk 3 Rotating Arm 6 Floating Optical Unit 8 Flexure 26 Deflection Mirror 29 First Relay Lens 26M Deflection Device 26a Galvano Mirror 26b Fixed Mirror 30 Second Relay Lens (Imaging Lens)

Claims (3)

[Claims] 1. A light beam incident on the galvanomirror, comprising: a galvanomirror having a reflective surface rotatable in a predetermined direction; and a fixed mirror arranged facing the reflective surface of the galvanomirror. Is incident on the fixed mirror at least once, and a light beam reflected by the fixed mirror is reflected by the galvano mirror again. 2. An optical information recording / reproducing head which is configured to deflect a parallel light beam emitted from a laser light source by a deflecting means, make it incident on an objective optical system, condense it on an optical disk, and receive the reflected light. 2. The deflecting means according to claim 1,
An optical information recording / reproducing head, comprising: a deflecting device. 3. The reflection surface of the galvanomirror is rotatable in a direction in which an incident angle of a parallel light beam incident on the objective optical system varies in an incident surface parallel to a tracking direction of the optical disc. The optical information recording / reproducing head according to claim 2.