JPH10188298A - Optical information recording or reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable high speed access to a recorded surface by composing a movable optical member only of a swingable galvano-mirror and a rotatable object lens being rotatable, thereby swinging a laser beam in the direction of a radius of a recording disk and mitigating the influence of inertia caused by the moving of the optical member. SOLUTION: Writing in a track is performed by the rotation of an optical information recording disk 1, writing in the other track is performed by swinging a galvano-mirror 11 by the prescribed angle θ, while an object lens 12 is rotated by 2θ being two times as much as the prescribed angle and moving an irradiation point of a laser beam. At this time, the galvano-mirror 11 is swung in left and right by the prescribed angle resisting the elasticity of a supporting member 23 by the interaction of magnetic force generated by energizing a coil 25 for swinging and a magnet 22 for swinging. This swinging characteristic is decided by magnetic circuit current characteristics of the coil 25 for swinging and the magnet 22 for swinging, the elasticity of the supporting member 23, and an inertia moment of the galvano-mirror 11 including the coil 25 for swinging, but as the galvano-mirror 11 is light and swung, high speed moving can be performed.

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 for recording / reproducing information on / from an optical information recording disk by using a laser beam emitted from a laser light source. More specifically, the present invention relates to an optical system capable of recording or reproducing information with a laser beam on an optical information recording disk such as a compact disk (CD) or a digital video disk (DVD) at a higher speed. The present invention relates to a type information recording or reproducing apparatus.

[0002]

2. Description of the Related Art With the development of multimedia, a high-density, large-capacity recording medium capable of recording a large amount of information such as digitalized still images and moving images, such as video and audio, is required. The optical information recording disk has advantages such as being a medium capable of handling high-density and large-capacity information, and being easy to freeze, frame-forward and random-access an image. The optical information recording disk that records digitized information is a read-only type based on the recording principle,
It is classified into write-once type and rewritable type. Reproduction only type is C
D, CD-ROM, etc., and recently, a read-only DVD has been released. The write-once type includes a perforation method, a phase change method, a bubble forming method, and the like, and the perforation method is frequently used. Rewritable type includes magneto-optical method, phase change (crystalline amorphous transformation)
Systems, organic dye systems, and the like. Of these, magneto-optical disks are frequently used. FIG. 6 shows the principle of a CD-ROM, a write-once disc, and a magneto-optical disc. CD-RO
M is for reproduction only, and as shown in FIG. 6 (a), uneven pits formed on the disk surface
A laser beam having a predetermined wavelength is converged and irradiated by an objective lens having a predetermined numerical aperture, and the intensity of reflected light is detected to reproduce information recorded on a disk. The write-once disc is capable of recording only once, as shown in FIG.
As shown in FIG. 6B, a laser beam having a predetermined wavelength is converged and irradiated by an objective lens having a predetermined numerical aperture, and pit holes are formed in a disk to record information.
As shown in FIG. 2, the intensity of reflected light is detected to reproduce information recorded on a disk. The magneto-optical disk is writable and erasable. As shown in FIG. 6D, a laser beam having a predetermined wavelength is converged and irradiated by an objective lens having a predetermined numerical aperture to reduce the coercive force. By applying a magnetic field while decreasing the direction, the direction of the perpendicular magnetization is reversed to record information, and as shown in FIG. 6 (e), by irradiating a laser beam, the Kerr effect based on the difference in the perpendicular magnetization direction is reduced. The information is reproduced by utilizing the rotation of the plane of polarization of the reflected light.

For example, a CD-ROM has a diameter of 120 m.
m, having a capacity capable of storing about 600 Mbytes of information on a disk having a thickness of 1.2 mm. A laser beam having a predetermined wavelength is formed on an uneven pit formed on the disk surface by an objective lens having a predetermined numerical aperture. Is condensed and irradiated, the intensity of reflected light is detected, and information recorded on a disk is read and reproduced. The read-only DVD has the same diameter as the CD-ROM and a thickness of 0.6 mm.
Are bonded together to form finer pits at a higher density than a CD-ROM, and record 4.7 Gbyte information on one side. The numerical aperture (NA) of the objective lens
Is made larger than that of a CD-ROM and the wavelength of a laser beam is made shorter than that of a CD-ROM, whereby a large amount of information can be reproduced at high density. DVDs are unified as the SD standard, and write-once and rewritable DVDs will be provided to the market in the future.

[0004] It is necessary to read out information from an optical information recording disk on which such information is recorded at a high density at high speed and accurately, and to write information onto the optical information recording disk at high speed and accurately. To read information from the optical information recording disk and write information to the optical information recording disk, the optical head is moved in the radial direction of the rotating optical information recording disk, and the laser beam is moved to the optical information recording disk. This is performed by condensing and irradiating the recording surface of the optical information recording disk, reading out the information written on the recording surface of the optical information recording disk, and writing the information on the recording surface.

FIGS. 7 and 8 show an example of a structure for reading information from an optical information recording disk. In the optical information recording disk shown in FIG. 7, the optical information recording disk (71) is supported by a turntable (73) of a spindle motor (72) and is rotated at a predetermined rotation speed. The reading of information from the recording surface of (71) is performed by an optical head (74) reciprocating in the radial direction of the optical information recording disk (71). The optical head (74) converts the laser beam emitted from the semiconductor laser (75) into a parallel beam by the parallel optical system (76), passes through the objective lens (77), and applies the laser beam to the recording surface of the optical information recording disk (71). The light is condensed and irradiated, and the reflected light therefrom is guided again to the objective lens (77).
8) The recorded information is read by detecting the intensity of the reflected light by converging it on the upper surface. The optical head (74) provided with such an optical system has a large size and a considerable weight. Reciprocating movement of the optical head (74) in the radial direction of the optical information recording disk (71) is performed by a well-known sliding mechanism such as a sliding mechanism using a rack-pinion, a sliding mechanism using a screw, or a linear motor. In order to read information from the optical information recording disk, the optical head (74) is moved at a high speed to a predetermined position in the radial direction of the optical information recording disk (71), and then read. It is necessary to stop instantaneously and accurately to access predetermined information.
Since the inertia based on the weight of 4) is large, high-speed access is difficult. In addition, an optical information recording disk (7
Repeating the movement and stoppage of the heavy optical head (74) in order to read the information from 1) also requires large power consumption.

FIG. 8 shows an optical head (81),
It is separated into an optical block (82) serving as a fixed portion and a movable block (83) in the radial direction of the optical information recording disk. The optical block (82) includes a semiconductor laser (84) and a parallel optical system ( 85), a sensor (86), and a condensing system (87) for the sensor are provided. A movable mirror (83) has a follower mirror (88) that reflects a parallel beam emitted from the optical block (82). ) And an objective lens (89). When the optical head (81) is separated in this manner, only the movable block (83) can be accessed by reciprocating in the radial direction of the optical information recording disk (71). Also, the influence of inertia upon access is reduced. However, the reciprocating movement of the movable block (83) in the radial direction of the optical information recording disk is performed by a sliding mechanism using a rack and pinion, as described above.
A well-known sliding mechanism such as a sliding mechanism using a screw or a sliding mechanism using a linear motor is adopted, and the movable block (83) has a structure having a heavy mechanism for reciprocating movement. For this reason, the influence of the inertia of the movable block (83) is not reduced as expected. When the movable block (83) reciprocates, the movable block (83) is moved so that the optical axis of the parallel beam emitted from the optical block (82) always coincides with the optical axis of the movable block (83). It is necessary to stably reciprocate the optical information recording disk in the radial direction, and moreover, the movable block (83) has to adopt a rigid structure with a certain weight so as not to vibrate during the reciprocation. Not get
From this point of view, the influence of the inertia of the movable block (83) has not been reduced significantly. Also, in order to read information from the optical information recording disk (71),
The power consumption due to repeated movement and stoppage of the movable block (83) is not so reduced. Such a structure for separating the optical system requires a long optical path length and requires high precision mechanically in order to keep the optical axis constant, which leads to an increase in manufacturing cost.

[0007]

SUMMARY OF THE INVENTION The present invention has been made as a result of earnest research in view of the above-described circumstances.
By reducing the weight of the movable optical member for reading information from the optical information recording disk or writing information to the optical information recording disk, high-speed writing to the recording surface of the optical information recording disk is achieved. It is an object of the present invention to provide an optical information recording or reproducing apparatus that enables access.

[0008]

In order to solve the above-mentioned problems, an optical information recording or reproducing apparatus according to the present invention comprises a movable optical member, a swingable galvanomirror and a rotatable objective. By using only the lens, the laser beam is swung in the radial direction of the optical information recording disk, the influence of inertia caused by the movement of the optical member is reduced as much as possible, and the recording surface of the optical information recording disk is accessed at high speed. Is possible. That is, in the optical information recording or reproducing apparatus of the present invention, the laser beam collimated in the optical block is reflected by the oscillating galvanomirror, and has a rotation angle twice the oscillating angle of the galvanomirror. 2fθ collected by a rotatable objective lens and disposed between the objective lens and an optical information recording disk
The recording surface of the optical information recording disk is irradiated as a minute spot through the lens and the convex lens, and the optical axis of the collected laser beam moves along the radial direction of the optical information recording disk. Features. Here, the 2fθ lens causes the laser beam condensed by the objective lens to be focused as a minute spot at an arbitrary position in the radial direction of the recording surface of the optical information recording disk, and the convex lens is used as the objective lens. The optical axis of the laser beam focused by the optical information recording disk is made perpendicular to the recording surface of the optical information recording disk. Then, the laser beam irradiated as a minute spot on the recording surface of the optical information recording disk reflects off the recording surface and
After passing through the fθ lens and the convex lens, the optical path returns again along the same optical axis as the outward path. Therefore, the laser beam collimated in the optical block is reflected by an oscillating galvanometer mirror set at a predetermined angle, condensed by a rotatable objective lens, and optical information recording via a 2fθ lens and a convex lens. A predetermined spot along the radial direction of the recording surface of the disc is irradiated as a minute spot, and information is read from the optical information recording disc along a track along with the rotation of the optical information recording disc, or to the optical information recording disc. Can be written.
Then, the galvanomirror is swung from a predetermined angle to another angle, and accordingly, the objective lens is swung so as to have a swivel angle twice as large as the swivel angle of the galvanomirror. Move the irradiation point of the beam to another position in the radial direction of the optical information recording disk, and read information from the optical information recording disk along other tracks on the recording surface of the optical information recording disk, or Information is written to the expression information recording disk. By repeating the same operation, the reading of information from the optical information recording disk or the writing of information to the optical information recording disk can be continued.

An optical block for emitting a laser beam emitted from the light source as a parallel laser beam;
An oscillating galvanomirror for reflecting the parallel laser beam, and a parallel laser beam rotatable at a rotation angle twice as large as the oscillating angle of the galvanomirror. An objective lens for illuminating the light, and a second lens disposed between the objective lens and the optical information recording disk.
It has an fθ lens and a convex lens, and the focused laser beam is irradiated as a minute spot on the recording surface of the optical information recording disk, and the optical axis of the laser beam moves along the radial direction of the optical information recording disk You may make it.

The galvanomirror is swingably movable about a swing axis orthogonal to the optical axis of the parallel laser beam and parallel to the recording surface of the optical information recording disk. The rotation axis may be the same axis as the rotation axis of the rotation axis, more specifically, the galvanomirror that can be rotated about the rotation axis, the parallel laser beam Has an axis perpendicular to the optical axis of the optical information recording disk and parallel to the recording surface of the optical information recording disk, and is supported by a support member fixed to the magnetic body for rocking. It is mounted so that it is located outside the magnetic body, and the objective lens is
The frame is supported by a frame via a focus actuator, and the frame is rotatable around a rotation support shaft having the same axis as the swing axis as a rotation axis, and the frame includes the rotation support shaft. It is preferable that a rotation coil for mounting a weight balance position with respect to the objective lens is attached, and a rotation magnetic body having the same axis as the rotation axis is disposed inside the rotation coil. According to this, the laser beam collimated in the optical block is reflected by a swingable galvanometer mirror set at a predetermined angle, condensed by a rotatable objective lens, and a 2fθ lens,
A predetermined spot along the radial direction of the recording surface of the optical information recording disc is irradiated as a minute spot through a convex lens, and information is read from the optical information recording disc along a track along with the rotation of the optical information recording disc. Alternatively, information can be written on an optical information recording disk. Next, the galvanomirror supported by the support member is swung from a predetermined angle to another angle due to the interaction between the magnetic force generated by the current flowing in the swing coil and the magnetic force generated by the current flowing through the swing coil. Then, with the rotation of the galvanomirror, the rotation coil is energized and the magnetic force generated by the current flowing through the rotation coil interacts with the magnetic body for rotation, and the rotation angle becomes twice the rotation angle of the galvanomirror. The frame is rotated about a rotation support shaft so that the irradiation point of the laser beam condensed by the objective lens is moved to another recording surface position in the radial direction of the optical information recording disk, and the optical information Information is read from or written to the optical information recording disk along other tracks on the recording surface of the recording disk. By repeating the same operation, reading of information from the optical information recording disk or writing of information to the optical information recording disk is continued. The pivot is
Since the objective lens provided on the frame and the rotation coil are at the weight balance position, the moment of inertia during rotation about the rotation support shaft of the frame is small, and a slight The rotation of the objective lens to the predetermined position can be easily and smoothly performed by supplying the electric power. The objective lens can be moved along the optical axis by the focus actuator, and the laser beam can be irradiated as a predetermined minute spot on the recording surface of the optical information recording disk.

Also, the 2fθ lens has a convex surface on the optical information recording disk side, and a narrow surface having a flat surface facing the convex surface and having at least a length corresponding to a recording area of the optical information recording disk. A convex lens having a flat surface on the side of the optical information recording disk, and having a length corresponding to at least a recording area of the optical information recording disk;
It is preferable that the biconvex surfaces of the lens and the convex lens are disposed to face each other. Since the 2fθ lens and the convex lens are narrow, a compact structure can be achieved.

In the optical block, a beam expander and a beam splitter are disposed on the optical axis of the laser beam from the light source, and the sensor and the sensor are arranged on the optical axis orthogonal to the optical axis from the beam splitter. Preferably, a light means is provided.

In the present invention, since the 2fθ lens and the convex lens are interposed between the objective lens and the recording surface of the optical information recording disk, the distance between the objective lens and the recording surface of the optical information recording disk is reduced. It becomes longer, and a long focal length objective lens is used.
The spot size when the laser beam is focused by the objective lens is proportional to the wavelength of the laser beam and inversely proportional to the numerical aperture (NA) of the objective lens.
Is proportional to the aperture radius of the objective lens and inversely proportional to the focal length (ie, aperture radius / focal length). Therefore, by making the parallel laser beam expanded by the beam expander incident on the objective lens,
When the focal length of the objective lens is long, the spot size of the laser beam focused by the objective lens can be set to a predetermined size suitable for irradiating the concave and convex pits on the recording surface of the optical information recording disk, and the optical information recording can be performed. Information can be read from the recording surface of the disc, or information can be written on the recording surface of the optical information recording disc. The beam splitter and the means for condensing the light on the sensor are for guiding the light reflected from the recording surface of the optical information recording disk to the sensor.

[0014]

Embodiments of the present invention will be described below, and the present invention will be described in more detail. Of course, the present invention is not limited by the following embodiments. In the embodiments described below, an optical information recording / reproducing apparatus will be described for convenience of description. However, the present invention is not limited to this, and a recording-only apparatus or a reproduction-only apparatus may be used. Therefore, in the following, a recording-only device and the like will be described as needed.

FIG. 1 shows the principle of an optical information recording / reproducing apparatus. As shown in FIG. 1, an optical information recording disk (1) is supported by a turntable (2) and is rotatable by a spindle motor (3). The optical system includes a collimator lens (7) on an optical axis (6) of a laser beam (5) emitted from the semiconductor laser (4),
A condenser lens (8), a beam expander (9), a beam splitter (10), a galvanomirror (11) capable of swinging about a swing axis (P), and the galvanomirror (1).
Objective lens (12) rotatable about rotation axis (Q) on the same axis as swing axis (P) of 1), 2fθ
A lens (13) and a convex lens (14) are provided,
An optical information recording disk (1) is provided on an optical axis (6) orthogonal to the optical axis (6) and the beam splitter (10).
An aperture lens (16) and a sensor (15) for narrowing the light reflected from the recording surface of the recording medium on the sensor (15) are provided. Here, the semiconductor laser (4), the collimator lens (7), the condenser lens (8), the beam expander (9), the beam splitter (10), the aperture lens (16), and the sensor (15) are an optical block (17). ). Galvo mirror (1
The swing axis (P) of 1) is orthogonal to the optical axis (6) and parallel to the recording surface of the optical information recording disk (1). Similarly, the rotation axis (Q) of the objective lens (12) is orthogonal to the optical axis (6) and parallel to the recording surface of the optical information recording disk. The galvanomirror (11) and the objective lens (12) are configured such that the objective lens (12) rotates with an angle twice as large as the swing angle of the galvanomirror (11). . The 2fθ lens (13) has a convex surface on the optical information recording disk side, the surface facing the convex surface is flat, and has a narrow width and a semi-cylindrical shape having a length corresponding to a recording area of the optical information recording disk. The convex lens (14) has a flat surface on the side of the optical information recording disk, and is a narrow-banded semi-cylindrical lens having a length corresponding to the recording area of the optical information recording disk. ) And the biconvex surfaces of the convex lens (14) are arranged to face each other. In FIG. 1, the galvanometer mirror (11) is at an initial position indicated by a solid line, and the irradiation point of the laser beam is located at a track position substantially at the center of the recording area of the optical information recording disk (1). Then, the galvanomirror (11) is swung right and left around the swing axis (P), and accordingly, the objective lens (12) is turned at a rotation angle twice the swing angle of the galvanomirror (11). By rotating the laser beam right and left about the axis of movement (Q), the irradiation point of the laser beam is moved in the recording area of the optical information recording disc (1) along the radial direction of the optical information recording disc (1). Then, the irradiation point of the laser beam is positioned at a predetermined track position, and information can be read from a predetermined track or written on a predetermined track by rotating the optical information recording disk (1). In FIG. 1, the incident angle of the laser beam (5) emitted from the beam splitter (10) to the galvanomirror (11) is oblique to the normal (X) of the galvanomirror (11) at the initial position. Angle (α). In FIG. 1, the angle (α) is set to approximately 43 °, but is not limited to this.

When reading and reproducing information recorded on the optical information recording disk (1), the laser beam emitted from the semiconductor laser (4) is converted into a parallel laser beam by a collimator lens (7) and collected. The light is condensed by an optical lens (8), the beam diameter is expanded by a beam expander (9), and the light is emitted from an optical block (17) through a beam splitter (10). The laser beam emitted from the optical block (17) is reflected by the galvanomirror (11) and enters the objective lens (12). The laser beam condensed by the objective lens (12) passes through the 2fθ lens (13) and the convex lens (14) and is irradiated as a minute spot on the recording surface of the optical information recording disk (1). The laser beam reflected by the pits on the recording surface of the optical information recording disk (1) passes through the convex lens (14), the 2fθ lens (13), and the objective lens (1).
2), reflected by the galvanometer mirror (11), returned to the beam splitter (10), reflected by the beam splitter (10), passed through the aperture lens (16), and collected on the sensor (15). Is done.
Then, the information recorded on the optical information recording disc (1) is reproduced by the sensor (15). With the rotation of the optical information recording disk (1), reading is performed along the track direction of the optical information recording disk (1),
For reading on other tracks, galvanometer mirror (11)
Is rotated by a predetermined angle (θ), and accordingly, the objective lens (12) is rotated by 2θ, and the irradiation point of the laser beam on the recording surface of the optical information recording disk (1) is set to the optical information recording disk (1). ) In the radial direction.

When information is recorded on the optical information recording disk (1), the laser beam emitted from the semiconductor laser (4) is converted into a parallel laser beam by the collimator lens (7), and the condensing lens (8). ), The beam diameter is expanded by a beam expander (9), and the beam is emitted from an optical block (17) through a beam splitter (10). The laser beam emitted from the optical block (17) is reflected by the galvanomirror (11) and enters the objective lens (12). Objective lens (1
The laser beam focused in 2) is a 2fθ lens (1
3) The light passes through the convex lens (14) and is irradiated as a minute spot on the recording surface of the optical information recording disk (1) to record predetermined information on the recording surface of the optical information recording disk (1). Writing along the track direction of the optical information recording disk (1) is performed with the rotation of the optical information recording disk (1), and writing to other tracks is performed by rotating the galvanomirror (11) by a predetermined angle ( θ) swings, and accordingly, the objective lens (12) is rotated by 2θ, and the irradiation point of the laser beam on the recording surface of the optical information recording disk (1) is shifted in the radial direction of the optical information recording disk (1). Is carried out.

The recordable / reproducible optical information recording disk may be a write-once disk, a magneto-optical disk, or the like. The optical information recording disk may be disposed so as to be movable in the radial direction of the disk, and move in accordance with the movement of the writing laser beam in the radial direction of the optical information recording disk. A well-known mechanism may be used for moving the magnetic head in the magneto-optical disk, and a detailed description is omitted. As the optical information reproducing apparatus, a video disk, a CD, a CD-ROM, a reproduction-only DVD, and the like can be used. Also, CD-RO
It is also possible to use a plurality of types of optical information recording disks such as M and DVD, and in such a case, for example, an objective lens having a partially different focal length may be used. It should be used.
As objective lenses having partially different focal lengths,
The one described in JP-A-6-215406 can be employed.

FIGS. 2 and 3 show the structure of the optical information recording / reproducing apparatus. Spindle motor (3), optical block (17), 2fθ lens (13), convex lens (14)
Are fixed to a base frame (not shown).
The swing of the galvanomirror (11) is performed by a moving coil type galvanomirror actuator (21). That is, a support member (23) of a galvanomirror (11) having a T-shaped cross section made of an elastic material such as rubber is provided in a groove provided on an upper surface of a block-shaped swinging magnet (22) fixed to a base frame. Is inserted and fixed,
The back surface of the disc-shaped galvanometer mirror (11) is fixed to the T-shaped upper surface of the support member (23), and the galvanometer mirror (1) is fixed.
1) is swingably supported by a block-shaped swing magnet (22). A tubular body (24) surrounding the swing magnet (22) is fixed to the galvanomirror (11), and a swing coil (25) is wound around the tubular body (24). A swing magnet (22) and a swing coil (2
5) constitutes a magnetic circuit for swinging the galvanometer mirror. The galvanomirror (11) is at the initial position shown in FIG. 2 when there is no current to the swing coil (25),
The galvanomirror (11) is tilted left and right by a predetermined angle against the elasticity of the support member (23) due to the interaction between the magnetic force generated by the current flowing by energizing the rocking coil (25) and the rocking magnet (22). Will be rocked. A voice coil can be used as the swing coil (25). By releasing the power to the swing coil (25),
The galvanomirror (1) is restored by the restoring force of the support member (23).
1) returns to the initial position. The oscillation characteristics of the galvanomirror (11) are as follows: the current carrying characteristics of the magnetic circuit between the oscillation coil (25) and the oscillation magnet (22); the elasticity of the support member (23);
Galvanometer mirror (11) including swing coil (25)
However, since the galvanometer mirror (11) is light and swings, high-speed movement is possible. Such a support member (23) having a T-shaped cross section functions as a kind of hinge, but is changed to such a structure. For example, the swing shaft is projected horizontally from the galvanometer mirror (11), and It is also possible to employ a moving coil type actuator that rotates around a swing axis. In addition, galvanometer mirror (11)
Is a disk shape, but is not limited to this, and it is needless to say that a suitable shape such as a square or an ellipse can be adopted.

At the tip of the plate-like frame (27), a support (28) is provided so as to protrude from the right side, and the support (28) is provided with a focus actuator (2).
The objective lens (12) is supported via 9), and a passage (28a) for passing a laser beam is provided. The frame (27) is rotatable around its pivot shaft (30) at its base end, and is turned around the base end of the frame (27) from the left side. A moving coil (31) is attached, and rotation about the rotation support shaft (30) is performed by a movable coil type actuator (32). Inside the turning coil (31), a turning magnet (33) having a circular cross section fixed to the base frame is provided, and the turning magnet (33) and the turning coil (3) are provided.
1) constitutes a magnetic circuit for rotating the objective lens (12). A linear coil can be used as the rotation coil (31). The rotation support shaft (30) protrudes from the center of the rotation magnet (33) and is inserted into the shaft hole of the frame (27), and the frame (27) can rotate around the rotation support shaft (30). It has been. The rotation support shaft (30) is coated with a fluorine resin or the like so that the rotation of the frame (27) is smoothly performed.
Is aligned with the rotation axis (Q) in FIG. The objective lens (12) and the coil for rotation (31) are mounted on the frame (27) so that the moment of inertia is reduced when the frame (27) is rotated about the rotation support shaft (30). It is provided at a position where its weight is balanced about the support shaft (30). The frame (27) is at the initial position shown in FIG. 2 when there is no current supply to the rotation coil (31), and the magnetic force generated by the current flowing when the current is supplied to the rotation coil (31) and the rotation magnet. By interacting with (33), the objective lens (12) is moved left and right about the pivot (30) against the elastic force of a coil spring (not shown). It is designed to rotate at twice the angle. By releasing the power supply to the rotation coil (31), the frame (27) returns to the initial position by the restoring force of the coil spring. The turning characteristics of the frame (27) are as follows: the current flowing characteristics of the magnetic circuit of the turning coil (31) and the turning magnet (33); the elasticity of the coil spring; the objective lens (12); Moment of inertia of the frame (27) including the rotation support shaft (3
0) is determined by the frictional resistance between the frame (27) and the like. However, since the moment of inertia of the frame (27) is small, high-speed rotation is possible. In addition, although the frame (27) is configured to rotate around a rotation support shaft protruding from the center of the rotation magnet (33), the structure is not limited to this. For example, FIG. ), A bearing is provided on the rotating magnet (33a),
A structure in which the frame rotates around a rotation support shaft fixed to the frame (27a), or, as shown in a conceptual diagram in FIG. 4B, independent of the rotation magnet (33b). The support leg is erected on the base frame, a bearing is provided on the support leg, and the bearing supports a rotation support shaft provided on the frame (27b), and the frame (27b) is centered on the rotation support shaft. It is needless to say that a structure or the like configured to rotate in a predetermined manner may be used.

The detection of the swing angle of the galvanometer mirror (11) and the rotation angle of the frame (27) are performed by appropriate position sensors. The optical information recording disk (1) is rotated by rotating the frame (27) at a rotation angle twice as large as the swing angle of the galvanomirror (11).
In order to allow the laser beam to access the predetermined track position, for example, a track control device (4) as shown in FIG.
0) may be used. This truck control device (40)
In order to allow the laser beam to access a predetermined track position of the optical information recording disk (1), first, a command signal from the disk radial position (41) and a signal from the tracking sensor (42) are added, Based on this, the galvanomirror actuator (2
1) operates, and the galvanomirror (11) is swung by a predetermined angle. The swing angle (θ) of the galvanomirror (11) is
The swing angle signal detected by the galvano position sensor (43) and detected by the galvano position sensor (43) is output as a double angle signal by the amplifier (44). The difference between the output from the amplifier (44) and the rotation angle signal indicating the rotation angle (2θ) of the objective lens (12) by the linear coil position sensor (45) is taken, and a linear coil actuator is used to eliminate the difference. By actuating (32), the objective lens (12) is rotated by twice the rotation angle (2θ) of the swing angle (θ) of the galvanomirror (11). By performing the access operation in this manner, instantaneous access becomes possible. In the access operation, only electric power is used for the operation of the galvanomirror actuator (21) for swinging the galvanomirror (11) and the operation of the linear coil actuator (32) for rotating the objective lens (12). As a result, power consumption is reduced.

The track control device (40) can also control a tracking error, and the focus actuator (29) may use only a one-dimensional drive type actuator using a voice coil. Become. It goes without saying that a two-dimensional drive type actuator can be used. A well-known method such as a three-beam method can be used as the tracking control, and a well-known method such as the astigmatism method can be used as the focus control, and a detailed description thereof will be omitted.

For example, when the radius of the optical information recording disk is 60 mm, which is the same as that of a CD-ROM, a DVD, or the like, the swing angle of the galvanometer mirror (11) and the rotation angle of the objective lens (12) are The swing angle of the galvanomirror (11) is in the range of 15 to 30 °, and therefore the objective lens (12)
Adopting a range of 30 to 60 degrees as the rotation angle of the lens may cause interference with the response speed of the galvano actuator (21) and the linear coil actuator (32), the focal length of the objective lens, the 2fθ lens, and the space occupied by the convex lens. This is preferable from the viewpoint of no presence.

[0024]

Since the present invention is configured as described above in detail, it has the following effects. In an optical information recording or reproducing apparatus, a laser beam collimated by an optical block is reflected by an oscillating galvanomirror, and the objective is rotatable at an angle twice as large as the oscillating angle of the galvanomirror. The light is condensed by a lens, and is irradiated as a minute spot on the recording surface of the optical information recording disk via a 2fθ lens and a convex lens disposed between the objective lens and the optical information recording disk,
Since the optical axis of the focused laser beam moves along the radial direction of the optical information recording disk, it is possible to read information from the optical information recording disk or to read information from the optical information recording disk. The movable optical member for writing information is a galvanometer mirror and an objective lens, which can reduce the weight of the movable optical member and enable high-speed access to the recording surface of the optical information recording disc. Become. Since the movable optical members are the galvanometer mirror and the objective lens, and furthermore, the galvanometer mirror is swung and the objective lens is rotated, the energy consumption required for the swing of the galvanometer mirror and the rotation of the objective lens is reduced. It requires less and is economical. Further, since the structure is simple, the manufacturing cost is low and the number of failures is small.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the principle of an optical information recording or reproducing apparatus according to the present invention.

FIG. 2 is a front view showing an embodiment of the optical information recording or reproducing apparatus of the present invention.

FIG. 3 is a side view of the apparatus of FIG. 2;

FIG. 4 is a conceptual diagram showing another example of a frame rotation mechanism.

FIG. 5 is a block diagram showing a control device in the optical information recording or reproducing device of the present invention.

FIG. 6 is an explanatory diagram of a recording or reproducing method for an optical information recording disk.

FIG. 7 is an explanatory diagram showing an example of a conventional structure for reading information from an optical information recording disk.

FIG. 8 is an explanatory diagram showing another example of a conventional structure for reading information from an optical information recording disk.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical information recording disk 3 Spindle motor 4 Semiconductor laser 7 Collimator lens 9 Beam expander 10 Beam splitter 11 Galvano mirror 12 Objective lens 13 2ftheta lens 14 Convex lens

Claims (6)

[Claims] 1. A laser beam collimated in an optical block is reflected by an oscillating galvanomirror, and is condensed by an objective lens that can rotate at twice the oscillating angle of the galvanomirror. The optical axis of the laser beam focused and irradiated as a minute spot on the recording surface of the optical information recording disk via a 2fθ lens and a convex lens disposed between the objective lens and the optical information recording disk The optical information recording or reproducing apparatus is characterized in that the optical information recording disk moves along the radial direction of the optical information recording disk. 2. An optical block for emitting a laser beam emitted from a light source as a parallel laser beam, a swingable galvanometer mirror for reflecting the parallel laser beam, and twice the swing angle of the galvanometer mirror. An objective lens that is rotatable at a rotation angle of and focuses the parallel laser beam reflected by the galvanometer mirror; and a 2fθ lens disposed between the objective lens and the optical information recording disk. A convex lens, and the focused laser beam is irradiated as a minute spot on the recording surface of the optical information recording disk so that the optical axis of the laser beam moves along the radial direction of the optical information recording disk. An optical information recording / reproducing apparatus characterized in that: 3. A galvanomirror is swingably movable about a swing axis perpendicular to an optical axis of the parallel laser beam and parallel to a recording surface of the optical information recording disk, and an objective lens is provided with the galvanomirror. 3. The optical information recording / reproducing apparatus according to claim 1, wherein the optical information recording or reproducing apparatus is rotatable about the same axis as the swing axis. 4. The galvanomirror, which is swingable about a swing axis, has an axis orthogonal to the optical axis of the parallel laser beam and parallel to the recording surface of the optical information recording disk. Supported on a support member fixed to the moving magnetic body, a swinging coil is attached to the galvanomirror so as to be located outside the swinging magnetic body, and the objective lens is connected via a focus actuator. Supported by a frame, the frame is rotatable around a rotation support shaft having the same axis as the swing axis as a rotation axis,
A rotating coil is attached to the frame so that the rotating support shaft has a weight balance position with the objective lens. Inside the rotating coil, a rotating magnetic body having the same axis as the rotating axis is provided. 4. The optical information recording or reproducing apparatus according to claim 1, wherein the optical information recording or reproducing apparatus is provided. 5. The 2fθ lens has a convex surface on the optical information recording disk side, a surface facing the convex surface is flat, and has a narrow width at least corresponding to a recording area of the optical information recording disk. The convex lens has a flat surface on the side of the optical information recording disk, and is a narrow width-shaped lens having a length corresponding to at least a recording area of the optical information recording disk. 5. The optical information recording / reproducing apparatus according to claim 1, wherein the biconvex surfaces of the convex lens are arranged to face each other. 6. An optical block, wherein a beam expander and a beam splitter are disposed on an optical axis of a laser beam from a light source, and a sensor and a sensor are arranged on the optical axis orthogonal to the optical axis from the beam splitter. 3. An optical system according to claim 1, wherein said light means is provided.
The optical information recording or reproducing apparatus according to 3, 4 or 5.