JPH0877562A - Optical disk device - Google Patents

Abstract

PURPOSE: To provide a recording control system capable of forming a stable and minute mark and to provide an optical disk device suitable for enlarging capacity by providing a recording light beam control means and making the recording control system into a feedback control system. CONSTITUTION: The same track 129 on an optical disk 128 is irradiated by at least two beams of a recording light beam 108 and a reproducing light beam 118. Then, the mark recorded by the recording light beam 108 is reproduced by the reproducing light beam 118 in a short time. Thus, a recording light beam radiation means 104 generates a control signal instantly based on a reproduced signal, and a recording control system is feedback-controlled for controlling the recording light beam radiation means 104. Thus, the minute mark is formed stably without being affected by disturbance such as focusing and tracking servo fluctuation of a device and medium sensitivity deviation. Thus, the high density recording reducing a mark size or a mark length is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device for recording and reproducing information by irradiating an optical disk with a light beam, and more particularly to an optical disk device suitable for increasing the capacity of recorded information.

[0002]

2. Description of the Related Art An optical disk device has been developed as an information storage device for recording and reproducing information by using an optical disk which is a high recording density rotary recording medium. Recording on an optical disk is performed by irradiating a light beam to raise the temperature of the optical disk and making changes in shape, composition or magnetism as marks. The reproduction from the optical disc is performed by irradiating a light beam and converting the information of the mark included in the reflected light from the optical disc into a reproduction signal by a photodetector.

A conventional optical disk device for recording and reproducing which seems to be most similar to the structure of the present invention will be described with reference to FIG. The recording pattern generation circuit 204 drives the recording semiconductor laser 206 based on the recording information generated by the recording information generation means 202.

The recording light beam 208 emitted from the recording semiconductor laser 206 passes through the collimator lens 220, the beam splitter 222, and the objective lens 224 and is focused on the track 229 on the optical disk 228. The condensed recording light beam 208 heats the optical disc 228 to form a mark according to the recorded information.

On the other hand, the reproducing light beam 218 emitted from the reproducing light beam irradiation means 214, for example, the reproducing semiconductor laser 216, passes through the collimating lens 220, the beam splitter 222, and the objective lens 224, and the recording light beam 208 is recorded. The light is focused on the same track 229.
The reflected reproduction light beam 218 is again reflected by the objective lens 22.
4, the beam path is changed by the beam splitter 222,
The reproduction light beam detection means 23 passes through the detection lens 226.
0, for example, the light is focused on the photodetector.

Since the optical disk 228 rotates in the rotation direction shown by the arrow in the figure, the reproducing light beam 218 reflected from the optical disk 228 contains the information of the mark recorded by the recording light beam 208, and the photo detector. 23
The output of 0 becomes a reproduction signal. The reproduced signal is compared with the recorded information by the recorded information confirmation means 232 to confirm the successful recording. If the recording fails, the recording is performed again after the optical disk has rotated once.

[0007]

In the above optical disk device, when the focusing and tracking servo fluctuations, the environmental fluctuations, the temporal fluctuations, the manufacturing defects, the adjustment defects, etc. occur, the output of the recording light beam fluctuates. The control system interprets that the disturbance A is added to the output of the recording light beam. Further, the mark diameter or the mark length fluctuates due to variations in medium sensitivity of the optical disc, environmental fluctuations, manufacturing defects, etc., so that the recording control system causes disturbance B in the mark forming process.
Is interpreted as being added. These disturbances change the mark diameter or the mark length, making it difficult to perform high-density recording with a reduced mark diameter or mark length.

It is an object of the present invention to form a fine mark stably without depending on focusing and tracking servo fluctuations of an optical disk device, medium sensitivity fluctuations, environmental fluctuations, temporal fluctuations, manufacturing defects, adjustment defects, and the like. Another object of the present invention is to provide a recording control system and an optical disk device suitable for increasing the capacity.

[0009]

The above object is achieved by using a feedback control system as the recording control system.

According to the present invention, at least two recording light beams and reproducing light beams are applied to the same track on the optical disk, and when recording information, the recording light beam is used for recording and reproducing. The information recorded by the light beam is reproduced, and the recording is performed while controlling the intensity of the recording light beam based on the reproduced signal.

As means for this purpose, a recording information generating means for generating recording information to be recorded on a track on the optical disk capable of recording and reproducing information, and at least one recording information on the track on the optical disk according to the recording information. A recording light beam irradiating means for irradiating a light beam, a reproducing light beam irradiating means for irradiating at least one reproducing light beam on the same track on the optical disc, and a reproducing light beam reflected from the optical disc are detected. A reproduction light beam detection means for generating a reproduction signal, a signal processing means for binarizing the reproduction signal to generate a binarized signal, and a rising edge or a falling edge of the binarized signal are detected to detect a first signal. First edge detecting means for generating one edge signal and one of the falling edge and rising edge of the binarized signal are detected to generate the second edge signal. Second edge detection means, a synchronization signal generation means for generating a synchronization signal in synchronization with the first edge signal, and when recording information, the above-mentioned recording purpose according to the phase difference between the synchronization signal and the second edge signal. A recording light beam control means for controlling the irradiation intensity or irradiation time of the light beam irradiation means or the irradiation intensity and irradiation time is provided.

[0012]

According to the present invention, since at least two beams of the recording light beam and the reproducing light beam are applied to the same track on the optical disk, the mark recorded by the recording light beam is shortened by the reproducing light beam. It is possible to play in time. The recording light beam control means immediately generates a control signal based on the reproduced reproduction signal and controls the recording light beam irradiation means, so that the recording control system becomes a feedback control system.

The recording light beam control means determines the irradiation intensity of the recording light beam irradiation means, the irradiation time, or the irradiation intensity according to the phase difference between the synchronizing signal synchronized with the first edge signal and the second edge signal. And control the irradiation time. In this case, the components of the feedback control system are as follows: the control target is the recording light beam irradiating means, the controlled amount is the phase difference between the synchronizing signal and the second edge signal synchronizing with the first edge signal, and the sensor is the reproducing light beam And reproducing light beam detecting means.

Disturbances are fluctuations in the intensity of the recording light beam due to focusing and tracking servo fluctuations, environmental fluctuations, temporal fluctuations, manufacturing defects, adjustment errors, etc., and variations in the medium sensitivity of the optical disk, environmental fluctuations, manufacturing defects, etc. There are fluctuations.

The ability of the feedback control system to suppress disturbances depends largely on its bandwidth. According to the present invention, since the control signal is immediately generated by the recording light beam control means based on the reproduced signal reproduced, the dead time is short and the phase delay of the control signal is small. Therefore, it is possible to widen the bandwidth of the feedback control system, and the reproduced signal that is the controlled amount is less likely to be affected by disturbance.
As a result, the accuracy of the mark diameter or the mark length is improved, and it becomes possible to perform high density recording with the reduced mark diameter or the mark length.

[0016]

EXAMPLE An example of the present invention will be described below. FIG. 1 is a diagram showing an embodiment of an optical disk device according to the present invention, and FIG. 2 is a diagram showing signal waveforms.

First, an optical disk device for recording and reproducing according to the present invention will be described with reference to FIGS. The recording light beam irradiation means 104 generates a feedforward pattern by the feedforward pattern generation circuit 105 based on the recording information generated by the recording information generation means 102, and drives the recording semiconductor laser 106. The recording light beam 108 emitted from the recording semiconductor laser 106 passes through the collimator lens 120, the beam splitter 122, and the objective lens 124, and passes through the track 12 on the optical disc 128.
Focus on 9. The condensed recording light beam 108 heats the optical disc 128 to form a mark corresponding to the recording information.

On the other hand, the reproducing light beam irradiating means 114, for example, the reproducing light beam 118 emitted from the reproducing semiconductor laser 116 passes through the collimator lens 120, the beam splitter 122, and the objective lens 124, and the recording light beam 108 is obtained. The light is focused on the same recording track 129. The reflected reproduction light beam 118 passes through the objective lens 124 again, the optical path is changed by the beam splitter 122, passes through the detection lens 126, and is condensed on the reproduction light beam detection means 130, for example, a photodetector.

Since the optical disk 128 rotates in the rotation direction shown by the arrow in the figure, the reproducing light beam 118 reflected from the optical disk 128 contains the information of the mark recorded by the recording light beam 108, and the photodetector. Thirteen
The output of 0 becomes the reproduction signal shown in FIG.

The signal processing means 134, for example, the waveform equalizing circuit and the binarizing circuit, generates the binarized signal shown in FIG. 2B from the reproduced signal, and the first edge detecting means 136 and the second edge detecting means 136. The edge detecting means 137 detects the binary signal from FIG.
The first edge signal and the second edge signal shown in (c) and (d) are generated. In FIG. 2, the rising edge is the first edge signal and the falling edge is the second edge signal, but the falling edge may be the first edge signal and the rising edge may be the second edge signal.

The synchronizing signal generating means 138, for example a PLL circuit, generates the synchronizing signal shown in FIG. 2 (e) which is synchronized with the first edge signal. The recording light beam control means 140 is
A control signal is generated according to the phase difference between the synchronization signal synchronized with the first edge signal and the second edge signal, and the recording light beam irradiation means 104 is controlled. The reproduced signal is compared with the recorded information by the recorded information confirmation means 132 to confirm the successful recording. If the recording has failed, the optical disc 128 is rotated once, and then the recording is performed again.

Next, the control signal and the recording semiconductor laser drive signal will be described with reference to FIG. FIG. 3 is a diagram for explaining a recording semiconductor laser drive signal. In Figure 3, (a),
The three control methods of (b) and (c) are shown. A recording semiconductor laser drive signal is generated by adding a control signal to each feedforward pattern. FIG.
3A is a DC value, FIG. 3B is a pulse peak value, and FIG.
(C) uses the last pulse time as a control signal. All of the marks are controlled so that the mark length is increased and the second edge signal is delayed. In order to shorten the mark length and control the tendency to advance the second edge signal, the polarity of the control signal may be inverted. Further, the same effect can be obtained by combining the three control methods of FIGS. 3A, 3B, and 3C.

In the optical disk device of the present invention, the mark recorded by the recording light beam 108 is changed to the reproducing light beam 118.
Therefore, it is possible to reproduce in a short time. The recording light beam control means 1 immediately based on the reproduced signal reproduced.
Reference numeral 40 generates a control signal, and the recording light beam irradiation means 10
4, the recording control system is feedback-controlled.

Disturbance A is intensity fluctuation of the recording light beam due to focusing and tracking servo fluctuations, environmental fluctuations, temporal fluctuations, manufacturing defects, adjustment errors, etc., and disturbance B is medium sensitivity variation of the optical disk 128, environmental fluctuations, manufacturing defects, etc. This is a variation in the mark formation process due to.

FIG. 4 is a block diagram of the control system. In the recording light beam control means 140, the phase comparator 142 detects the phase difference between the synchronization signal synchronized with the first edge signal and the second edge signal, and according to the phase difference, the control element 144, for example, the phase compensation circuit. Generate a control signal. as a result,
A feedback control system is constructed with one feedforward input. Constituent elements are the control target is the recording light beam irradiation means 104, the controlled amount is the phase difference between the synchronization signal and the second edge signal synchronized with the first edge signal, and the sensor is the reproduction light beam 118 and the reproduction light beam. Detection means 130
Is. The disturbance A is the intensity variation of the recording light beam 108, and the disturbance B is the variation of the mark forming process 180.

Finally, the effect of the present invention will be described with reference to FIG. FIG. 5 is a diagram showing the bandwidth of the feedback control system with respect to the reproduction signal detection delay time. The condition is that the phase delay of the feedback control system is 18 degrees in the bandwidth. For example, when the distance between the recording light beam and the reproducing light beam on the optical disk is 10 μm and the linear velocity of the track on which the light beam is located is 10 m / s, the reproduction signal detection delay time is 1 μs.

At this time, the bandwidth of the feedback control system can be set to 50 kHz. The ability of a feedback control system to suppress disturbances depends largely on its bandwidth. According to the present invention, the reproduction signal which is the controlled variable is 50
It is less likely to be affected by a disturbance that occurs below kHz. That is, it is possible to stably form minute marks without depending on focusing and tracking servo fluctuations of the optical disk device, medium sensitivity fluctuations, environmental fluctuations, temporal fluctuations, manufacturing defects, adjustment defects, and the like. As a result, it is possible to perform high density recording with a reduced mark diameter or mark length.

[0028]

According to the present invention, since the recording control system is a feedback control system, the mark shape can be recorded with high accuracy without depending on disturbance, and the mark diameter or mark length is reduced. High-density recording can be performed.

[Brief description of drawings]

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

FIG. 2 is a signal waveform diagram according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a recording semiconductor laser drive signal.

FIG. 4 is a block diagram of a control system according to another embodiment of the present invention.

FIG. 5 is a characteristic diagram showing a bandwidth of a feedback control system with respect to a reproduction signal detection delay time.

FIG. 6 is a block diagram showing a conventional optical disc device.

[Explanation of symbols]

102 ... Recording information generating means, 104 ... Recording light beam irradiating means, 105 ... Feedforward pattern generating circuit, 106 ... Recording semiconductor laser, 108 ... Recording light beam, 114 ... Reproducing light beam irradiating means, 116 ... Reproducing Semiconductor laser, 118 ... Reproducing light beam, 120 ... Collimating lens, 122 ... Beam splitter, 124 ...
Objective lens, 126 ... Detection lens, 128 ... Optical disk, 129 ... Track, 130 ... Playback light beam detection means, 132 ... Record information confirmation means, 134 ... Signal processing means,
136 ... First edge detecting means, 137 ... Second edge detecting means, 138 ... Synchronous signal generating means, 140 ... Recording light beam control means.

Claims (1)

[Claims] 1. A recording information generating means for generating recording information to be recorded on a track on an optical disk capable of recording and reproducing information, and at least one recording light on the track on the optical disk according to the recording information. A recording light beam irradiating means for irradiating a beam, a reproducing light beam irradiating means for irradiating at least one reproducing light beam on the same track on the optical disk, and detecting the reproducing light beam reflected from the optical disk And a reproduction light beam detecting means for generating a reproduction signal, a signal processing means for binarizing the reproduction signal to generate a binarized signal, and detecting a rising edge or a falling edge of the binarized signal. First edge detecting means for generating a first edge signal and a second edge signal by detecting a falling edge or rising edge of the binarized signal. A second edge detecting means for generating,
A synchronization signal generating unit that generates a synchronization signal that synchronizes with the first edge signal; and when recording information, the recording light beam irradiation unit of the recording light beam irradiation unit according to the phase difference between the synchronization signal and the second edge signal. An optical disk device comprising: a recording light beam control means for controlling irradiation intensity, irradiation time, or irradiation intensity and irradiation time.