JPH0322227A - optical disc device - Google Patents

Abstract

PURPOSE:To enlarge the transfer rate of information by providing a light source rotating means to rotate a light source to an optical axis by plural tracking signals, which are obtained an optical disk, in a multi-beam optical disk device. CONSTITUTION:When an interval between mutual tracks 26 is changed, it is necessary to change the arranging direction of optical spots 21-25 on an optical disk 17. Thus, a tracking error signal is obtained from the optical spot 21 and an error signal is obtained from the optical spot 23. Since deviation in the arranging direction of the optical spots 21-25 can be known when the tracking error signals are obtained from the optical spots 21 and 23, a semiconductor laser actuator 28 is driven so as to correct the deviation. Practically, tracking control is executed in the presentative optical spot, for example, in the optical spot 21 and the actuator 28 is driven so that the tracking error signal to be obtained from the optical spot 23 can be made zero.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical disc device, particularly a multi-beam optical disc device.

BACKGROUND OF THE INVENTION In recent years, applications of optical disks have attracted attention. However, it is often inferior to existing memory devices in terms of data transfer rate, making it difficult to apply them.

Conventional optical disc devices perform tracking control and focusing control to write information on and read information from the disc. However, both have one information track.

(For example, "Electronic Materials J, July 1988 issue, page 76 -
81 pages. ) Problems to be Solved by the Invention However, with the above structure, there is a problem that the information transfer rate cannot be increased due to the limitation of the number of revolutions of the disk and the limitation of the laser power. Was.

In view of the above problems, the present invention provides an optical disc device with a high information transfer rate. Means for Solving the Problems In order to solve the above problems, the optical disc device of the present invention includes:
a light source that emits a plurality of independent optical signals; a light focusing means that focuses the light source onto a record carrier; a light detector that receives signals returned from the record carrier; and a plurality of tracking signals obtained from the light detector. The apparatus is equipped with a light source rotation means that rotates the light source with respect to the optical axis in response to a signal. Further, the optical disc device of the present invention includes a light source that emits a plurality of independent optical signals, a light converging means that converges the light source onto a record carrier, and a reference signal that receives a signal returned from a light spot on a pregroove of the record carrier. The light source is equipped with a reference tracking control means for controlling the tracking of the light source, and a light source rotation means for rotating the light source with respect to the optical axis based on signals returned from other light spots.

Further, the optical disc device of the present invention includes a light source that emits a plurality of independent optical signals, a light converging means that converges the light source onto a record carrier, and a forcing error that returns from a light spot on a pregroove of the record carrier. The apparatus is provided with an optical axis tilt correction means for receiving a signal and correcting a difference in optical axis tilt between the optical disk and a focusing lens provided in the light converging means.

Further, the optical disc device of the present invention includes a light source that emits a plurality of independent optical signals, a light converging means that converges the light source onto a record carrier, and a forcing error that returns from a light spot on a pregroove of the record carrier. The optical disc tilt adjusting means receives a signal and adjusts the tilt of the optical disc in order to correct the difference in optical axis tilt between the optical disc and the focusing lens provided in the light converging means. be.

Further, the optical disc device of the present invention includes a light source that emits a plurality of independent optical signals, a light converging means that converges the light source onto a record carrier, and a forcing error that returns from a light spot on a pregroove of the record carrier. The apparatus further comprises a focusing lens 1st position adjusting means which receives a signal and adjusts the position of the focusing lens in order to correct the difference in optical axis inclination between the optical disk and the focusing lens provided in the total light converging means. It is equipped with discipline.

Further, the optical disc device of the present invention includes a light source that emits a plurality of independent optical signals, a light converging means that converges the light source onto a record carrier, and a light source that aligns the light source with the optical axis based on track spacing information of a pregroove of the record carrier. The light source rotating means is provided with a light source rotating means for rotating the light source.

Further, the optical disc device of the present invention includes a light source that emits a plurality of independent optical signals, a light converging means that converges the light source onto a record carrier, and a light spot at the outermost periphery of a plurality of light spot arrays on the record carrier. and a light source rotation means for rotating the light source with respect to the optical axis so as to track an adjacent pregroove. Further, the optical disc device of the present invention includes a light source that emits a plurality of independent optical signals, a light converging means that converges the light source onto a record carrier, and a tracking error that returns from a light spot on a pulley group of the record carrier. A light source rotation means for rotating the light source with respect to the optical axis based on disc eccentricity information obtained from the signal is provided.

Further, the optical disc device of the present invention includes a light source that emits a plurality of independent optical signals, a light converging means that converges the light source onto a record carrier, and a tracking error signal returned from a light spot on a pregroove of the record carrier. The apparatus is equipped with a light source rotation means for rotating the light source with respect to the optical axis based on disk eccentricity information and disk position information obtained from the above. The above-mentioned means for solving the problems of multi-beam optical discs may be implemented individually or simultaneously as necessary.

Generally, the light source mentioned above may be any coherent light source such as a semiconductor laser or a helium-neon laser. However, in the case of the multi-beam laser of the present invention, a semiconductor laser is often used due to the positional accuracy of the light source. The light converging means includes a focusing lens that converges the light emitted from the light source onto the disk, and a focusing means that controls focusing and tracking by moving the focusing lens.
This is caused by tracking methods. The light detector uses a light receiving element such as a silicon photodiode. Since the light source rotation angle is normally as small as about 0.1 degrees, the light source rotation means uses a mechanism that holds the focusing lens barrel with a rotatable spring, such as silicone rubber, and has an actuator attached around it to move it in the rotational direction. A variety of actuators are used, including those based on the principle of a rotating motor. The tracking signal is generated using the so-called three-beam method ("Electronics", March 1986 issue, p. 56), the phase difference method ("Optical Technology Contact 23 (7), p. 486)," or the push-pull method (
``Optical Technology Contact Attachment (7), page 502) etc. are used.There are various variations in the actual form of the three-beam method, phase difference method, and push-bull method.(In particular, the circuit devices are different.)The pregroove is It is also called a track guide groove and is an uneven groove. ("Electronics" March 1986 issue, p. 54). This is created in advance when the disc is manufactured. The reference tracking control signal is a tracking error signal obtained from the pre-groove section, and a method different from other tracking error detection methods is used to distinguish it from tracking signals obtained from other tracks and prevent tracking from being applied to the wrong position. ．． For example, the push-pull method is used to detect basic tracking errors, and the phase difference method is used to detect tracking errors from other tracks. The optical disc tilt adjustment means tilts the entire stand on which the disc is placed. The focusing lens tilt adjusting means tilts the entire light converging means or only the focusing lens portion.

Pre-groove track spacing information is recorded on the disc in advance when the disc is manufactured.

Write information during so-called formatting. Operation The present invention enables multi-beam recording and reproduction by the above-described structure and provides a high transfer rate optical disc device.

EXAMPLE An optical disc according to an example of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram illustrating the outline of an optical disc device according to an embodiment of the present invention. In Fig. 1, l is the light source part, l° is an enlarged view of that part as seen from the optical axis direction, 2 is the part where the light converges on the disc, 2° is an enlarged view of the disc surface of that part, and 3 is a photo This is the detector portion, and 3° is an enlarged view of that portion viewed from the optical axis direction. 1l is a multi-beam semiconductor laser with five beams, and the spot interval is 100 μm. A permanent magnet l2 is attached to the cap of this laser.

The outer diameter of this laser is φ7mm, and the outer diameter is φ12mm.
m, and is held by a silicone rubber damper l3 with an inner diameter of 1 m. 14 and 14° are coils, which are mounted at symmetrical positions with respect to the optical axis of the multi-beam semiconductor laser. By passing a current through the coil 14, the multi-beam semiconductor laser 11 rotates around the optical axis. Permanent magnet 1
2. Guard the semiconductor laser actuator 28 with the coil l4. Light emitted from the multi-beam semiconductor laser 11 passes through a half mirror l5 and a focus lens 16 and is converged onto an optical disk 17. The light reflected from the optical disk 17 passes through the focus lens 16, the half mirror 15, and the cylindrical lens 18, and enters the photodetector 19. The light spots 21 to 25 on the optical disk l7 are converged onto photodetector elements 21 to 25 on the photodetector l9, respectively. Reference numeral 26 indicates tracks on the optical disc 17, and the center track is a track in the form of a pregroove. The light spot 21 lies on the pregroove therein. A focus lens actuator 27 adjusts the radial tilt of the focus lens 16. (The focus lens actuator is also used for tracking,
There is one for focus, but it is omitted. ) In FIG. 1, if the mutual spacing of the tracks 26 changes, the optical disc 1
The direction of the arrangement of the light spots 21 to 25 on 7 must be changed. Therefore, a tracking error signal is obtained from the optical spot 21 using the push-pull method, and an error signal is obtained from the optical spot 23 using the phase difference method. photo detector l
For this reason, the photodetector element hit by the light spot 2F on 9 is divided into two parts. (In the figure, it is divided into four, but this is to obtain a focus error signal.) Since the phase difference method obtains an error signal from the signal itself, there is no need to divide the photodetector element. If tracking error signals are obtained from optical spots 21 and 23, optical spot 2
Since the deviation in the direction of the arrangement of numbers 1 to 25 is known, the semiconductor laser actuator 28 is driven to correct it.
Specifically, a typical light spot, for example, light spot 2
1 performs tracking control, and controls the semiconductor laser actuator 28 so that the tracking error signal obtained from the optical spot 23 becomes zero. Note that the tracking error signal may be obtained from any track other than those listed above. During recording, when there is only one pregroove for a multitrack, it is necessary to accurately control the track spacing using this track as a reference when recording other tracks. At this time,
Use two methods.

1) Use track interval information recorded in advance on the optical disc 17 in a preformatted form. 2) Record while tracking the adjacent track using the outermost spot.

In case l), the semiconductor laser actuator 28 is rotated based on the track spacing information to adjust and record the track spacing. In case 2), for example, in FIG. 1, the semiconductor laser actuator 28 is controlled so that the optical spot 23 tracks its own pregroove track and the optical spot 25 tracks the adjacent pregroove. At this time, even with a 5-beam multi-beam semiconductor laser, only optical spots 21 and 22 can be used for recording. 23. There will be 24 4 beams.

Furthermore, in case 1) above, if the disk is eccentric, the rotation angle with respect to the optical axis of the multi-beam semiconductor laser must be changed depending on the rotational position. Eccentricity information is light spot 2
This can be seen from the tracking error signal obtained from l. Therefore, it is preferable to control the semiconductor laser actuator 28 using this signal.

In the case of 1), the center of the disc and the focus lens 1
If the moving line from the inner circumference to the outer circumference of the light spot 6 is misaligned, the angle between the track and the direction in which the light spots 2l to 25 are arranged changes between the inner circumference and the outer circumference. That is, in FIG. 2, 51
indicates tracks (plurality) of the optical disc. 50 is a line of movement of the inner and outer peripheries of the focus lens l6. Due to this movement, the direction in which the light spots 21 to 25 are arranged basically remains unchanged. However, if this line of movement does not pass through the center of rotation of the disk, point 52 in FIG. The track directions 54 and 55 at 53 are different. At this time, if the distance between the center of the disk and the inward/outward convergence movement line of the 50 focus lens 16 is known from the eccentricity information and the disk position information, then the direction in which the light spots are lined up at the focus lens 16 is calculated. The semiconductor laser actuator 28 is controlled based on this result and disk eccentricity information.

If the disc is warped, or if the optical axis of the optical head that serves as a light focusing means is misaligned with the disc surface from the beginning, all beams may not be in focus due to multiple beams. At this time, the focus deviation of the light spots is calculated based on focusing error signals obtained from a plurality of light spots, and the tilt of the focus lens 16 is changed. The focus lens actuator 27 shown in Figure 1 is used for this purpose. This can be achieved using an electromagnetic actuator. Ideally, the entire optical head should be moved. Also, it is best to have two degrees of freedom for movement, but at least be able to change the inclination in the radial direction of the disk. Experimentally, defocusing in this direction has the greatest effect on the deterioration of recorded and reproduced signals. FIG. 3 shows an embodiment in which the entire optical head is controlled to tilt in the radial direction of the disk. In Fig. 3, 77 has one end attached to the pin 77.
A lever 78 rotatably supported by the lever 7
A permanent magnet 79 attached to the other end of the magnet 6 is a coil fixed at a position facing the permanent magnet 78. An optical head 75 is mounted on the lever 76. When a current is passed through the coil 79, a vertical force acts on the permanent magnet 78, causing the lever 76 to rotate around the pin 77.

Now, the entire forcing control is performed using the light spot 2l. If the optical axes of the optical disk 17 and the optical head 75 do not match, for example, the optical spot 23 will be defocused. The coil 7 is designed to make this defocus error signal zero.
Apply current to 9.

Furthermore, when controlling the tilt of the focus lens 16,
Controls the focus lens actuator 27. It is clear that the focusing error signal can also be obtained from the error rate, etc. Above, as examples of the multi-beam optical disc, the direction control of the arrangement of light spots in various cases, the uniform focusing control of each light spot, etc. have been described. These may be carried out individually or simultaneously as necessary. Effects of the Invention As described above, the present invention includes a light source that emits a plurality of independent optical signals, a light converging means that converges the light source onto a record carrier, and an optical detector that receives the signal returned from the record carrier. , a light source rotation means for rotating the light source with respect to the optical axis by a signal obtained from the optical detector or an optical axis tilt correction means for correcting the optical axis difference between the optical disk and the focusing lens, thereby increasing the information transfer rate. It is possible to provide an extremely large optical disc device.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating the outline of an optical disk device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the necessity of controlling the rotation of a multi-beam semiconductor laser used in the present invention, and FIG.
The figure is a schematic diagram showing an example of optical head tilt control used in the present invention. 11...Multi-beam semiconductor laser, 15...
... Half mirror, l6 ... Focus lens, 17 ... Optical disc, 18 ...
Cylindrical lens, 19...Photodetector, 21
~25...Light spot, 26...Track, 27...Focus lens actuator, 28...Semiconductor laser actuator.

Claims (9)

[Claims] (1) a light source that emits a plurality of independent optical signals; a light converging means that converges the light source onto a record carrier; an optical detector that receives signals returned from the record carrier; An optical disc device comprising: a light source rotation means for rotating the light source with respect to an optical axis using a plurality of tracking signals. (2) A light source that emits a plurality of independent optical signals, a light converging means that converges the light source onto a record carrier, and a reference tracking control that receives a signal returned from a light spot on a pregroove of the record carrier. An optical disc apparatus characterized by comprising a reference tracking control means and a light source rotation means for rotating the light source with respect to an optical axis based on a signal returned from another light spot. (3) a light source that emits a plurality of independent optical signals; a light converging means that converges the light source onto a record carrier; An optical disc device comprising an optical axis tilt correction means for correcting an optical axis tilt difference between the focusing lens and the focusing lens provided in the light converging means. (4) a light source that emits a plurality of independent optical signals; a light convergence means that converges the light source onto a record carrier; 1. An optical disc device comprising: an optical disc tilt adjustment unit that adjusts the tilt of the optical disc to correct a difference in optical axis tilt between the optical disc and a focusing lens provided in the light convergence unit. (5) a light source that emits a plurality of independent optical signals; a light converging means that converges the light source onto a record carrier; An optical disc device comprising: a focusing lens tilt adjusting means for adjusting the tilt of the focusing lens in order to correct a difference in optical axis tilt between the focusing lens and the focusing lens provided in the light converging means. (6) a light source that emits a plurality of independent optical signals; a light convergence means that converges the light source onto a record carrier; and a light source rotation that rotates the light source with respect to the optical axis based on track spacing information of a pregroove of the record carrier. An optical disc device comprising: means. (7) A light source that emits a plurality of independent optical signals, a light converging means that converges the light source onto a record carrier, and tracking of adjacent pregrooves with the outermost light spot of a plurality of light spot arrays on the record carrier. An optical disc device comprising: a light source rotating means for rotating the light source with respect to an optical axis so as to rotate the light source with respect to an optical axis. (8) A disc obtained from a light source that emits a plurality of independent optical signals, a light convergence means that converges the light source onto a record carrier, and a tracking error signal returned from a light spot on a pregroove of the recorder. and a light source rotation means for rotating the light source with respect to an optical axis based on eccentricity information. (9) a light source that emits a plurality of independent optical signals; a light focusing means that focuses the light source onto a record carrier; and disk eccentricity information based on a tracking error signal returned from a light spot on a pregroove of the record carrier. and a light source rotation means for rotating the light source with respect to an optical axis based on information about the position of the optical disc.