JP2726168B2 - Optical disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for optically recording / reproducing information, and more particularly, to a highly accurate control for correcting a track shift and a focus shift of a light spot focused on an information recording surface. The present invention relates to an optical disk device configured as described above.

[0002]

2. Description of the Related Art FIG. 4 is a schematic diagram showing an example of a conventional write-once optical disc apparatus. In FIG. 1, reference numeral 1 denotes a semiconductor laser serving as a light source, and emits a light beam 16. Reference numeral 2 denotes a collimator lens, 3 denotes a shaping prism, 4 denotes a beam splitter (hereinafter referred to as PBS), 5 denotes a λ / 4 wavelength plate, and 6 denotes an objective lens on an information recording surface of a disk 7 rotated by a disk motor 13. A light spot 17 is formed. 8
Is a condenser lens, and 9 is a half prism, which divides a light beam into transmitted light 16a and reflected light 16b. Reference numeral 10 denotes a knife edge, 11 and 12 denote two-split photodetectors, 14 denotes a focus correction actuator, and 15 denotes a track correction actuator.

[0003] Next, the operation of the write-once optical disc apparatus configured as described above will be described. That is, the light beam 16 emitted from the semiconductor laser 1 passes through the shaping prism 3, the PBS 4, and the λ / 4 wavelength plate 5, and forms a condensed light spot 17 on the information recording surface of the disk 7 by the objective lens 6. The light beam reflected by the disk 7 travels backward and is reflected by the PBS 4, passes through the condenser lens 8, and is split by the half prism 9 into transmitted light 16 a and reflected light 16 b. The transmitted light 16a is received by the split photodetector 12, and the differential output B detects a track shift of the focused light spot 17 with respect to an information recording track (not shown). The reflected light 16 b is received by the split photodetector 11 after half of the light beam is cut off by the knife edge 10, and the condensed light spot 17
Of the information recording surface is detected, and all the received light outputs C are detected as information signals.

On the other hand, since the disk 7 is rotated at a high speed (for example, 1800 rpm) by the disk motor 13, the condensed light spot 17 may cause a track shift with respect to the information recording track on the disk 7 due to image blur or eccentricity. Defocus occurs on the information recording surface. For this reason, the focus shift detection signal A and the track shift detection signal B
Are added to respective control circuits (not shown), and actuators 14 and 15 for driving the objective lens 6 in two dimensions indicated by arrows E and D are drive-controlled.

The two-dimensional driving actuators 14, 1
5 is configured as shown in FIG. 5 and FIG.
Is a plan view showing details of the two-dimensional driving actuators 14 and 15, and FIG. 6 is a sectional view thereof. In the figure,
Reference numeral 20 denotes a fixed shaft whose surface is coated with a Teflon-based resin, and which stands upright on a fixed base 32. 21 is an aluminum bearing, 22 is a movable holder, which holds the objective lens 6 at its eccentric position. Reference numeral 23 denotes a balancer, and reference numeral 24 denotes a rubber damper, which defines the operation center of the movable holder 22. 25
Is a support shaft for supporting the rubber damper 24 on the fixed base 32. 26 is a magnet for a focus correction actuator, 27 is a yoke which forms a magnetic circuit with the magnet 26, 28 is a focus control coil arranged in the magnetic circuit, 29a and 29
b is a magnet for a track correction actuator, 30a, 30
b is a track correction coil, 31a and 31b are magnets 2
9a and 29b constitute a yoke constituting a magnetic circuit.

In the above configuration, the fixed shaft 20 provided on the fixed base 32 and the bearing 21 provided on the movable holder 22
Is rotatably supported by a low friction between the Teflon resin and the aluminum. The movable holder 22 holds the objective lens 6 at a position eccentric from the axis, and a focus provided on the movable holder 22. A control coil 28 is arranged in a magnetic circuit composed of a magnet 26 and a yoke 27, and a desired current is supplied to the control circuit 28 to perform focus correction in the direction of arrow D. Similarly, the track correction coils 30a, 30b provided on the movable holder 22 are arranged in a magnetic circuit composed of the magnets 29a, 29b and the yokes 31a, 31b. Track correction is performed in the direction of arrow E. Here, balancer 2
3 stabilizes the operation as described above, and the rubber damper 24 works to define the operation center of the movable holder 22.

[0007] The focus control system block of such an optical disk device has a configuration as shown in FIG. In the figure,
The detection system G1, the amplification circuit G2, the phase compensation circuit G3, and the actuator G4 are constituent elements.
b is the control error and c is the movement of the actuator. The track control system has the same configuration. That is, while moving the objective lens 6 in the optical axis direction to correct the defocus,
This is to correct the track deviation by moving the track in a direction perpendicular to the track.

[0008]

Since the conventional optical disk apparatus is configured as described above, the correction operation is performed by moving only the objective lens, and the disk is rotated at a high speed to improve the transfer rate. Therefore, the objective lens must be moved at high speed. For example, the acceleration is increased by about the square of the number of rotations of the disk.
At 3600 rpm, about four times the actuator driving force is required for rotation at rpm. Furthermore, the control band is expanded with an increase in the rotational speed, and the mechanical resonance frequency generated in the actuator needs to be significantly increased with the increase in the rotational speed. This is inconsistent with the viewpoints of miniaturization, reduction of power consumption, and relaxation of design constraints, and has been a major problem in designing a high-performance optical disk device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and can realize downsizing, power consumption, and freedom of design, and enable high-speed rotation of a disk to greatly increase a transfer rate. It is an object of the present invention to provide an optical disk device that can be improved.

[0010]

An optical disk apparatus according to the present invention irradiates a light beam emitted from a light source to an information recording surface of a disk, detects a defocus of a light spot with respect to the information recording surface, and detects the information defocus. In an optical disc apparatus that detects a track shift of a light spot with respect to a recording surface and controls a focus shift and a track shift of the light spot on the information recording surface based on the information, a light beam from the light source is used to control information of a disc. A first light spot position control device for correcting a position of an objective lens for condensing light on a recording surface in at least one direction of an optical axis direction or a direction orthogonal to a track; A second light spot position control device for correcting in at least one of an axial direction and a direction perpendicular to the track, and the first light spot Position correction by the置制control device, the main
The first light spot position control device is responsible for the low frequency region below the predetermined frequency of the disk vibration, and the position correction by the second light spot position control device is mainly responsible for the high frequency region above the predetermined frequency of the disk vibration. And a frequency coupling compensating circuit for setting a disk vibration frequency region to be corrected by the light spot position control device or the second light spot position control device, respectively. The light source is housed integrally with the light source in a package to drive the element part of the light source.

[0011]

In the optical disk apparatus according to the present invention, a light beam emitted from a light source is applied to the information recording surface of the disk to detect a defocus of the light spot with respect to the information recording surface, and to detect the light spot with respect to the information recording surface. In an optical disc device that detects a track shift and controls a focus shift and a track shift of a light spot on the information recording surface based on the information, a light beam from the light source is focused on the information recording surface of the disc. A first light spot position control device for correcting the position of the objective lens for at least one of an optical axis direction or a direction perpendicular to the track, and a light beam of the light source, A second light spot position control device for correcting in at least one of a direction and a direction orthogonal to the track, and the first light spot position control Position correction by location mainly responsible for the predetermined frequency below the low frequency area of the disk vibration, position correction by the second light spot position control apparatus, a main
To charge the high-frequency range above a predetermined frequency of the disk vibration Te, and a frequency coupling compensation circuit for setting the disk vibration frequency region where the first or the second light spot position control apparatus for correcting each The second light spot position control device is housed integrally with the light source in a package of the light source to drive an element portion of the light source. By integrally packaging the position control device together with the light source, the following operation can be achieved.

That is, in the optical disk device according to the present invention,
According to this, the driving by the second light spot position control device is performed.
The second part is used as an element part in the light source.
Dramatically reduced the light spot position controller and its driving force
Can be reduced, the second light spot position
It is possible to realize miniaturization and low power consumption of
The second light spot position control device can be
By storing them together in a package,
It is possible to increase the rigidity of the second light spot position control device.
This allows the second light spot position control
The device is designed for mechanical resonance caused by the high speed rotation of the disk.
Higher frequency band control
The second light spot position control device , which can be performed,
Since the second optical spot is
Handle the position control device together with the light source.
When assembling the optical pickup
Workability etc. is greatly improved, and it can be used for other optical parts.
The second light spot position control device, which can also improve the placement accuracy with respect to
By being housed integrally with the light source in the package.
And supplies the light to the light source and the second light spot position control device.
Power line connected to the lead frame in the package
The second light spot.
The power supply to the position control device and the light source is easily performed.
Can be done.

[0013]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an optical disk device according to an embodiment of the present invention. In FIG. 1, the same or corresponding parts as those in the conventional example shown in FIG. Omitted.

In FIG. 1, reference numeral 40 denotes a first piezoelectric element for focus correction for driving the semiconductor laser 1 in the optical axis direction indicated by an arrow F, 41 denotes a movable holding plate, and 42 denotes a track of the semiconductor laser 1 indicated by an arrow G. The second piezoelectric element for track correction, which is driven in a direction perpendicular to the above, constitutes a second light spot position driving device with the first piezoelectric element 40. Also,
Although a two-dimensional actuator (first light spot position driving device) for driving the objective lens 6 is not shown here,
This is the same as the conventional configuration shown in FIGS.

FIG. 2 is a block diagram of the focus control system of the above embodiment. In FIG.
Is an amplification / compensation circuit, G7 is a piezoelectric element 40 for driving the semiconductor laser 1, G8 is a frequency coupling compensation circuit, and G9 is an actuator 14 for driving the objective lens 6 in the optical axis direction. Here, d is the surface vibration of the disk 7, e is the control error,
f is the movement of the objective lens 6, and g is the movement of the focused light spot.

Then, the first driving for correcting the objective lens 6 is performed.
Actuators 14 and 15 and first and second piezoelectric elements 40 and 42 for correcting and driving semiconductor laser 1
The first actuators 14 and 15 mainly perform the correction of sharing below z, ie, the sharing ratio of the first actuators 14 and 15 increases as the frequency decreases. The first and second piezoelectric elements 40 and 42 mainly share and correct the frequency or higher, that is, as the frequency increases, the sharing of the second position driving device including the first and second piezoelectric elements 40 and 42 increases. The ratio will increase. Although the focus control system has been described here,
The tracking control system has the same configuration.

Next, the operation of the above configuration will be described. The actuator 14 that drives the objective lens 6 shares a relatively low frequency region (up to several hundred Hz), and the piezoelectric element 40 that drives the semiconductor laser 1 shares a relatively high frequency region (several hundred Hz or more). Therefore, it is possible to cope with the high-speed rotation of the disk 7 without significantly increasing the driving force of the actuator 14 in the high frequency range and without increasing the mechanical resonance frequency so much, thereby greatly improving the transfer rate. Can be done. Further, in the focus control system, the movement of the semiconductor laser 1 covering the high frequency region is about 1 μm, and in the tracking control system, it is 0.1 μm.
It is only necessary to correct the minute amount, and there is no optical effect, and it is easy to increase the mechanical resonance.

In the above embodiment, the entire semiconductor laser 1 is configured to be driven for correction. However, in order to further reduce the size and improve the efficiency, the semiconductor laser 1 is constructed in a semiconductor laser package as shown in FIG. May be.

In FIG. 3, reference numeral 50 denotes a semiconductor laser package, 51 denotes a semiconductor laser element, 52 denotes a silicon mount, 53 denotes a heat sink, and 54 denotes a first driving the semiconductor laser element 51 in the direction of arrow F via the heat sink 53. A piezoelectric element, 55 is a support plate holding one end of the piezoelectric element 54, and 56 is a second piezoelectric element for driving the semiconductor laser element 51 in the direction of arrow G via the support plate 55.

Although the detailed wiring of the semiconductor laser element 51 is omitted, according to the configuration of FIG. 3, the weight of the movable portion to be driven can be greatly reduced, so that further miniaturization and simplification can be achieved. .

[0021]

As described above, according to the optical disk apparatus of the present invention, the light beam emitted from the light source is applied to the information recording surface of the disk, and the defocus of the light spot with respect to the information recording surface is detected. An optical disc device that detects a track shift of a light spot with respect to the information recording surface and controls a focus shift and a track shift of the light spot on the information recording surface based on the information; A first light spot position control device for correcting a position of an objective lens for condensing light on an information recording surface of a disk in at least one direction of an optical axis direction or a direction perpendicular to a track, and a light beam of the light source A second light spot position control device for correcting the light spot in at least one of an optical axis direction and a direction orthogonal to the track; Position correction by Tsu preparative position controller mainly responsible for the predetermined frequency below the low frequency area of the disk vibration, the second position correction by the light spot position control apparatus, mainly above a predetermined frequency of the disk vibration
The first or the second so as to take charge of the high frequency region of
And a frequency coupling compensating circuit for setting a disk vibration frequency region to be corrected by each of the light spot position control devices. The second light spot position control device is integrated with the light source in a package of the light source. Housed so as to drive the element part of the light source,
By packaging the second light spot position control device integrally with the light source as described above, the second light spot position control device is driven by the second light spot position control device as an element portion in the light source. Since the light spot position control device can be significantly reduced in weight and its driving force can be reduced, the second light spot position control device can be reduced in size and power consumption can be realized. By integrally storing the light spot position control device in the package of the light source, the rigidity of the second light spot position control device can be increased. Since the control device is less susceptible to mechanical resonance caused by high-speed rotation of the disk, it can perform control in a higher frequency band. Since the second light spot position control device is packaged together with the light source, the second light spot position control device can be handled integrally with the light source. Is very good, and the arrangement accuracy with respect to other optical components can be improved. By storing the second light spot position control device integrally with the light source in a package of the light source, Since the power supply lines for supplying the light source and the second light spot position control device can be connected to the lead frame in the package and arranged, the power supply of the second light spot position control device and the power supply of the light source can be performed. Therefore, the driving force can be improved, the mechanical resonance can be improved, and the control band can be improved. Such like, freed from the constraints of the optical disk apparatus designed, miniaturization of the device, simplified, it is possible to reduce power consumption, also enables high-speed rotation corresponding optical disc apparatus,
It is possible to easily improve the transfer rate of the entire apparatus, and it is possible to perform a highly accurate correction.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an optical disk device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a control system of the optical disk device according to the present invention.

FIG. 3 is a perspective view of a semiconductor laser driver according to another embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing a conventional optical disk device.

FIG. 5 is a plan view of an objective lens driving device in a conventional device.

FIG. 6 is a longitudinal sectional view of FIG.

FIG. 7 is a block diagram of a control system of a conventional optical disk device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Semiconductor laser (light source) 6 Objective lens 7 Disk 14 Focus correction actuator (first light spot position driving device) 15 Track correction actuator (first light spot position driving device) 16 Light beam 17 Focused spot 40, 42 Piezoelectric element (second light spot position driving device)

Claims (1)

(57) [Claims] 1. A light beam emitted from a light source is applied to an information recording surface of a disc to detect a focus shift of a light spot with respect to the information recording surface and to detect a track shift of the light spot with respect to the information recording surface. An optical disc device for controlling a focus shift and a track shift of a light spot on the information recording surface based on the information, a position of an objective lens for condensing a light beam from the light source on the information recording surface of the disc; A first light spot position control device for correcting the light beam in at least one direction of an optical axis direction or a direction perpendicular to the track; and a light beam of the light source in at least one direction in the optical axis direction or a direction perpendicular to the track. A second light spot position control device for correcting the position, and the position correction by the first light spot position control device ,
Primarily responsible for the predetermined frequency below the low frequency area of the disk vibration, the second position correction by the light spot position control apparatus is mainly to charge the high-frequency range above a predetermined frequency of the disk vibration, the first A light spot position control device or a frequency coupling compensation circuit for setting a disk vibration frequency region to be corrected by the second light spot position control device, respectively, wherein the second light spot position control device An optical disk device, wherein the optical disk device is housed integrally with the light source in a package to drive an element part of the light source.