JP2003196868A - Optical recording and reproducing device, and control method for the optical recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a mark part from being crystallized and to perform stable servo-control when a phase change type optical disk is placed in standby reproduction. <P>SOLUTION: The light beam intensity of laser light in standby reproduction is subjected to pulse modulation and signals needed for servo-control or signals similar to them are sampled and held for use in timing of synchronizing with the pulse modulation on the light beam intensity. The pulse-modulated pulse intensity of a light beam is equalized to the light beam intensity in conventional information reproduction and the bottom intensity of the pulse-modulated light beam intensity is set above zero and below the peak intensity. Consequently, the irradiating energy becomes small to suppress crystallization. Signals needed for servo-control in the standby reproduction are sampled and held in synchronism with the peak part of the pulse-modulated light beam intensity to stabilize the servo-control. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording / reproducing apparatus and a control method thereof for recording a signal on a phase-change optical disk using a laser beam or reproducing a signal recorded on a phase-change optical disk. In particular, it relates to suppression of deterioration of the recording signal in the standby reproduction state.

[0002]

2. Description of the Related Art There is a phase change type optical disk as one of recordable optical information recording media. Recording of a signal on a phase-change optical disk is performed by irradiating a rotating phase-change optical disk with a light beam of a laser beam from a semiconductor laser and heating and melting the phase-change recording film of the optical disk. At this time, the temperature reached and the cooling process of the phase change recording film differ depending on the intensity of the light beam emitted from the semiconductor laser,
Phase change A phase change of the recording film occurs.

That is, when the intensity of the light beam is high, the phase change recording film is heated to a temperature equal to or higher than the melting point and then rapidly cooled, so that the phase change recording film becomes amorphous. When the light beam intensity is relatively weak, the phase change recording film is heated to about the crystallization temperature and then gradually cooled to be in a crystalline state. Usually, the amorphized portion is called a mark portion and the crystallized portion is called a space portion. Then, the binary information is recorded with the mark portion and the space portion.

During reproduction of recorded information, the phase change recording film is irradiated with a light beam having a weak intensity so as not to cause a phase change, and a difference in optical characteristics between an amorphous state and a crystalline state, that is, a reflectance change. Alternatively, a reproduction signal is obtained by optically detecting a change in transmittance.

FIG. 6 is a block diagram showing the outline of a conventional optical recording / reproducing apparatus. In FIG. 6, a phase-change optical disk 110 is placed on a turntable 111 and rotationally driven by a spindle motor 112 at a constant linear velocity (CLV) or a constant angular velocity (CAV).

The optical pickup 133 collects the light beam of the semiconductor laser on the signal surface of the phase-change optical disk 110 and traces a track formed on the phase-change optical disk 110 in a concentric or spiral shape. And the objective lens 115 has a biaxial mechanism 116.
It is supported so as to be movable in the focus direction and the tracking direction. Also optical pickup 1
The whole 33 can be moved in the radial direction of the disk by the sled mechanism 122.

Laser diode 1 serving as a laser light source
The laser light emitted from 18 is collimated by a collimator lens, is incident on the beam splitter, and is transmitted through the beam splitter.
The light is condensed by 5 and is irradiated onto the phase change type optical disk 110 as a light spot.

The laser light reflected by the phase change type optical disk 110 passes through the objective lens 115 and then enters the beam splitter again. The laser light reflected by the beam splitter is condensed by the condenser lens and the photodetector 117. Imaged above.

In the photodetector 117, conversion into a received light current is made according to the amount of received light. This received light current is output to the RF amplifier 125. The RF amplifier 125 includes a current-voltage conversion circuit, an amplification circuit, a matrix circuit (RF matrix amplifier), and the like, and generates a necessary signal based on the signal from the photodetector 117. The RF amplifier 125 generates, for example, an RF signal that is reproduction data, a push-pull signal for servo control, a focus error signal, a tracking error signal, and a pull-in signal that is a sum signal of reflected light.

The RF signal generated by the RF amplifier 125 is subjected to waveform equalization by the equalizer after the high frequency signal is cut off by the low-pass filter in the binarization circuit 127, and is binarized by a predetermined slice level. And converted into a digital signal sequence. Further, in the binarization circuit 127, a clock signal is generated from the binarized signal using the PLL.

The digital signal sequence and the clock signal output from the binarization circuit 127 are demodulated by the data demodulation circuit 129 and subjected to error correction processing according to a predetermined method, and then stored in the buffer memory 134, and the interface circuit 132. Is output to an external device (not shown).

The servo control circuit 124 includes the RF amplifier 12
Focus error signal and tracking error signal of 5,
And various servo drive signals for focus, tracking, sled, and spindle based on operation commands from the system controller 131, and the biaxial control circuit 1
13, thread control circuit 120, spindle control circuit 1
It outputs to 14.

When recording information on the phase change optical disk 110, data supplied from an external device (not shown) is sent to the data modulation circuit 130 via the interface circuit 132. The data modulation circuit 130 adds an error correction code and an encoding process to the transmitted data according to a predetermined method, and further, the phase change optical disc 1
The recording data is generated by performing the modulation process for recording on the recording medium 10.

The record data is supplied to the laser drive circuit 119, the laser emission waveform is modulated, and a laser diode drive signal in which a required recording level and erasing level are combined is generated. The emission beam intensity of the laser diode 118 is modulated based on the laser diode drive signal, so that information consisting of a mark portion and a space portion is recorded on the phase-change optical disc 110.

[0015]

In such an optical recording / reproducing apparatus, in the standby reproduction state (generally called still reproduction) in which desired information is not recorded or reproduced, reproduction is performed in the standby reproduction state. Servo control is performed to maintain the track position. Performing such servo control is important for improving the access speed of the subsequent recording or reproducing operation.

That is, as shown in FIG. 7B, in the standby reproduction state, the laser beam has a predetermined beam intensity P11.
Always driven by. At this time, the beam intensity P11 of the laser beam is set to a beam intensity at which sufficient reflected light is obtained by the photodetector 117 and the S / N ratios of the push-pull signal, the focus error signal, and the tracking error signal can be kept good. The beam intensity P11 is 0.3, for example.
It is 5 mW. As described above, by constantly driving the laser light with the predetermined beam intensity P11 during the standby reproduction, the RF amplifier 125 can always obtain the output signal S11 of a certain level or more as shown in FIG. 7A. This RF
A push-pull signal, a focus error signal, or a tracking error signal can be obtained from the output signal of the amplifier 125, servo control can be performed, and the access speed of the subsequent recording or reproducing operation is improved.

However, if the laser beam is always driven at the predetermined beam intensity P11 during the standby reproduction, the temperature of the disk is always increased during the standby reproduction, and the recorded information, that is, the mark in the amorphous state is recorded. There arises a problem that the portion gradually crystallizes due to many temperature increases. As a result, information is lost or the quality of the information signal is deteriorated.

Therefore, it is proposed to prevent such crystallization of the mark portion during standby reproduction by lowering the beam intensity P11 of the laser light during reproduction during standby reproduction. That is, it is a method of suppressing the temperature rise of the mark portion and suppressing the crystallization by lowering the energy applied to the mark portion in the amorphous state.

However, if the beam intensity P11 of the laser light is lowered during the standby reproduction in order to prevent the mark portion from crystallizing during the standby reproduction, the amount of light reflected from the phase change type optical disk decreases. As a result, deterioration of the S / N ratio of a signal obtained by converting the amount of reflected light into an electric signal, that is, a focus error signal required for servo control, a tracking error signal, and a pull-in signal that is a sum signal of reflected light is prevented. This causes a problem that stable servo control is hindered.

Therefore, an object of the present invention is to prevent crystallization of the mark portion during standby reproduction, and
An object of the present invention is to provide an optical recording / reproducing device and a control method of the optical recording / reproducing device that enable stable servo control.

[0021]

According to the present invention, at the time of writing, the optical disk is irradiated with a laser beam modulated by a recording signal, at the time of reading, the optical disk is irradiated with a laser beam, and the reflected light is received to receive an optical disk. In an optical recording / reproducing apparatus having an optical pickup that outputs a reproduction signal, a unit that generates a servo error signal from the output of the optical pickup, and a unit that performs servo control based on the servo error signal, recording and reproduction are not performed. When performing the standby reproduction such that the optical pickup holds the track position on the optical disk and stands by, a means for pulse-modulating the light beam intensity from the optical pickup and a servo error signal is transmitted during the standby reproduction. A means for performing servo control by sample-holding in synchronization with the pulse for modulating the beam intensity is provided. It is an optical type recording and reproducing apparatus characterized by the the.

According to the present invention, at the time of writing, the optical pickup irradiates the optical disk with laser light modulated by a recording signal, at the time of reading, the optical pickup irradiates the optical disk with laser light, and the optical pickup receives the reflected light. A reproducing method for outputting an optical disk reproduction signal, generating a servo error signal from the output of the optical pickup, and performing servo control based on the servo error signal. Instead, when performing the standby playback such that the optical pickup holds the track position on the optical disk and waits, the intensity of the light beam from the optical pickup is pulse-modulated and the servo error signal is output when the standby playback is performed. Servo control is performed by sampling and holding in synchronization with the pulse that modulates the intensity. A control method of an optical recording reproducing apparatus, characterized in that had Unishi.

In the optical recording / reproducing apparatus according to the present invention, the light beam intensity of the laser beam at the time of standby reproduction is pulse-modulated, and a focus error signal, a tracking error signal, a pull-in signal, or other signals necessary for servo control, or these signals. A signal similar to (3) is sample-held and used at the timing synchronized with the pulse modulation of the light beam intensity.

When the peak intensity of the pulse-modulated light beam is used as the conventional light beam intensity at the time of reproducing information and the bottom intensity of the pulse-modulated light beam is set to zero or more and less than the peak intensity, the laser light Compared to the conventional information reproduction in which the beam intensity is constant, the irradiation energy becomes smaller.

By thus reducing the energy when irradiated, the temperature of the mark portion in the amorphous state can be suppressed and the crystallization can be suppressed.

On the other hand, the signal required for servo control during standby reproduction is sampled and held in synchronization with the peak portion of the pulse-modulated light beam intensity. The S / N ratio of the signal obtained by this is equivalent to that at the time of conventional information reproduction in which the light beam intensity of the laser light is constant, and therefore, it is possible to realize the same stabilization of servo control as in the conventional case.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an outline of the optical recording / reproducing apparatus of this example. In FIG. 1, reference numeral 10 is an optical disk capable of recording and reproducing. The recordable / reproducible optical disc 10 is a phase change type optical disc.

Recording of a signal on a phase change type optical disk is performed by irradiating a rotating phase change type optical disk with a light beam of a laser beam from a semiconductor laser to heat and melt a phase change recording film of the optical disk. Data is recorded by causing a phase change of the phase change recording film depending on the intensity of the irradiating light beam. When the intensity of the light beam is high, the phase change recording film is heated to a temperature equal to or higher than the melting point and then rapidly cooled, so that the phase change recording film becomes amorphous. When the light beam intensity is relatively weak, the phase change recording film is heated to about the crystallization temperature and then gradually cooled to be in a crystalline state. The amorphized portion is called a mark portion, and the crystallized portion is called a space portion, and binary information is recorded with the mark portion and the space portion.

FIG. 2 is a structural diagram showing an example of a sectional structure of the phase change type optical disk. In FIG. 2, reference numeral 50 is a transparent resin substrate. The transparent resin substrate 50 is made by injection molding method using polycarbonate. On the surface thereof, information tracks, that is, guide grooves for tracking servo are spirally formed with a depth of 40 nm and a pitch of 0.32 μm.

More specifically, on the transparent resin substrate 50,
A reflective layer 51 made of Ag alloy having a thickness of 100 nm is deposited. Furthermore, a corrosion prevention layer 52 made of SiN having a thickness of 10 nm, a first dielectric layer 53 made of ZnSiO 2 having a thickness of 5 nm, and AgGeSb having a thickness of 12 nm are further formed thereon.
Recording layer (phase change material) 54 made of Te, thickness 25 nm
The second dielectric layer 55 made of ZnS-SiO2 and the thermal damage reduction layer 56 made of SiN having a thickness of 25 nm are sequentially deposited by sputtering. Furthermore, an ultraviolet curable resin having a thickness of 100 μm is formed on the laminated film,
The transparent cover layer 57 is formed by spin coating.

In FIG. 1, a phase change type optical disk 10 is shown.
Is placed on a turntable 11 and is rotationally driven by a spindle motor 12 at a constant linear velocity (CLV) or a constant angular velocity (CAV). Then, the optical pickup 33 records the information on the signal surface of the phase-change optical disk 10 or reproduces the information recorded on the signal surface.

As shown in FIG. 3, the optical pickup 33
Is a laser diode 18 serving as a light source of laser light.
And an optical system including an objective lens 15, a beam splitter 60, a collimator lens 61, and a condenser lens 63, and a photodetector 17 for detecting laser light reflected by the phase-change optical disk 10.
Here, the objective lens 15 is supported by a biaxial mechanism 16 (FIG. 1) so as to be movable in the focus direction and the tracking direction. The entire optical pickup 33 can be moved in the radial direction of the disc by the sled mechanism 22.

In FIG. 1, the laser light reflected by the phase-change optical disk 10 is imaged on the photodetector 17 and converted into a received light current according to the amount of received light.
This received light current is supplied to the RF amplifier 25.

The RF amplifier 25 is a current-voltage conversion circuit,
An amplifier circuit, a matrix circuit, and the like are provided, and a necessary signal is generated based on the signal from the photodetector 17. RF
The amplifier 25 generates, for example, an RF signal that is reproduction data, a push-pull signal for servo control, a focus error signal, a tracking error signal, and a pull-in signal that is a sum signal of reflected light.

RF is a reproduction RF output from the amplifier 25.
A low-pass filter in the binarization circuit 27 cuts off a high-frequency signal, the equalizer performs waveform equalization on the signal, binarizes it at a predetermined slice level, and converts it into a digital signal string. . Furthermore, in the binarization circuit 27,
A clock signal is generated from the binarized signal using the PLL.

The output of the binarization circuit 27 is the data demodulation circuit 2
9 is supplied. The data demodulation circuit 29 receives the digital signal sequence and the clock signal output from the binarization circuit 27, and performs data demodulation and error correction processing according to a predetermined method. The demodulated data is accumulated in the buffer memory 34, and via the interface circuit 32,
It is output to an external device (not shown).

When recording information on the phase-change optical disk 10, data supplied from an external device (not shown) is sent to the data modulation circuit 30 via the interface circuit 32. The data modulation circuit 30 adds an error correction code and an encoding process to the received data according to a predetermined method, and further performs a predetermined modulation process for recording on the phase change optical disk 10 to record data. Is generated.

The recorded data is recorded in the laser driving circuit 19
The laser diode drive signal is generated by performing modulation on the laser emission waveform to generate a laser diode drive signal in which a required recording level and erasing level are combined. The light beam intensity of the laser diode 18 is modulated based on the laser diode drive signal, and information consisting of a mark portion and a space portion is recorded on the phase-change optical disc 10.

The push-pull signal, the focus error signal, and the tracking error signal output from the RF amplifier 25 are passed through two paths by the switch circuit 23,
It is supplied to the servo control circuit 24.

The first signal path is used only during standby reproduction, and at this time, the switch circuit 23 is set to the contact b side. In the first signal path, the push-pull signal, the focus error signal, and the tracking error signal output from the RF amplifier 25 are sent to the sample hold circuit 26 and supplied from the timing generation circuit 28 in the sample hold circuit 26. The sample is held in synchronization with.

Specifically, during standby reproduction, the laser diode 18 is pulse-driven and pulse-modulated laser light is output. The sample and hold are performed in synchronization with the timing when the light beam intensity of the pulse-modulated laser light reaches the peak intensity. Sample hold circuit 26
The push-pull signal, the focus error signal, and the tracking error signal sample-held by (4) are supplied to the servo control circuit 24 via the b-side contact of the switch circuit 23.

The second signal path is used in cases other than the standby reproduction, and at this time, the switch circuit 23 is set to the contact a side. In the second signal path, the RF amplifier 25
The push-pull signal, focus error signal, and tracking error signal output from
It is supplied to the servo control circuit 24 via the side contact.

The switch circuit 23 is a switch for selecting the path of the push-pull signal, the focus error signal, and the tracking error signal input to the servo control circuit 24 based on a command from the system controller 31, and specifically, The path of the signal is switched depending on whether or not it is in the standby reproduction state.

The timing generation circuit 28 generates a timing signal related to pulse modulation of laser light intensity during standby reproduction and supplies it to the laser drive circuit 19. Further, the timing generation circuit 28 generates a timing signal for sample-holding the push-pull signal, the focus error signal, and the tracking error signal during the standby reproduction, and supplies the timing signal to the sample-hold circuit 26.

The servo control circuit 24 is a switch circuit 23.
Various servo drive signals for focus, tracking, sled, and spindle are generated from the push-pull signal, the focus error signal, the tracking error signal, etc., which are sent via, and the servo operation is executed. That is, a focus drive signal and a tracking drive signal are generated according to the focus error signal and the tracking error signal, and are supplied to the biaxial control circuit 13.

The biaxial control circuit 13 comprises a focus coil driver and a tracking coil driver for controlling the focus coil and the tracking coil of the biaxial mechanism 16. The focus coil driver supplies the drive current generated based on the focus drive signal to the focus coil of the biaxial mechanism 16 to move the objective lens 15 to the phase-change optical disk 1.
Drive in the vertical direction of 0. The tracking coil driver supplies the drive current generated based on the tracking drive signal to the tracking coil of the biaxial mechanism 16 to drive the objective lens 15 to move along the radial direction of the phase-change optical disk 10. . As a result, a focus servo loop and a tracking servo loop are formed by the optical pickup 33, the RF amplifier 25, the sample hold circuit 26, the timing generation circuit 28, the switch circuit 23, the servo control circuit 24, and the biaxial control circuit 13.

Further, the servo control circuit 24, the spindle rotation speed set by the system controller 31,
The spindle drive signal is generated by comparison with the actual rotation speed of the spindle motor 12, and the spindle control circuit 14
Supply to. The spindle control circuit 14 applies a drive signal to the spindle motor 12 in response to the spindle drive signal, and rotationally drives the spindle motor 12 so that the required rotation speed is achieved.

The servo control circuit 24 uses a thread error signal obtained from the low frequency component of the tracking error signal,
A sled drive signal is generated based on a command from the system controller 31 and supplied to the sled control circuit 20. The sled control circuit 20 drives the sled mechanism 22 according to the sled drive signal. Thread mechanism 2
Reference numeral 2 denotes a mechanism for moving the entire optical pickup 33 in the radial direction of the phase-change optical disk 10. The sled control circuit 20 drives a sled motor inside the sled mechanism 22 in response to a sled drive signal. Proper movement of the optical pickup is performed.

Further, the servo control circuit 24 designates the operation mode of the laser drive circuit 19.

The laser drive circuit 19 controls the light emission drive of the laser diode 18 in the optical pickup 33. The laser drive circuit 19 includes a servo control circuit 24.
According to the operation mode designated by, that is, the information recording mode, the information reproducing mode, and the standby reproducing mode, a driving current for executing a predetermined laser emission is generated to drive the laser diode 18. That is, during the information recording, the light emission drive current according to the recording data sent from the data modulation circuit 30 is generated, and during the standby reproduction, the light emission according to the timing signal related to the pulse modulation sent from the timing generation circuit 28 is generated. Generate drive current.

As described above, in the optical recording / reproducing apparatus for the phase change type optical disk to which the present invention is applied, the push-pull signal, the focus error signal, and the tracking error signal output from the RF amplifier 25 are used only in the standby reproduction. Is supplied to the servo control circuit 24 via two paths, a first path used for the above and a second path used for cases other than the standby reproduction.

During the standby reproduction, the laser light from the optical pickup 33 is pulse-modulated, and the push-pull signal, focus error signal, and tracking error signal output from the RF amplifier 25 are sent to the sample hold circuit 26 and sampled. The sample is held in the hold circuit 26 in synchronization with the timing supplied from the timing generation circuit 28.

When the peak intensity of the pulse-modulated light beam is set as the light beam intensity during conventional information reproduction, and the bottom intensity of the pulse-modulated light beam intensity is set to zero or more and less than the peak intensity, the laser light Compared to the conventional information reproduction in which the beam intensity is constant, the irradiation energy becomes smaller. By reducing the irradiation energy in this way, it is possible to suppress the temperature rise of the mark portion in the amorphous state and suppress the crystallization.

On the other hand, the signal required for servo control during the standby reproduction is sample-held by the sample-hold circuit 26 in synchronization with the peak portion of the pulse-modulated light beam intensity. The S / N ratio of the signal obtained by this is equivalent to that at the time of conventional information reproduction in which the light beam intensity of the laser light is constant, and therefore, it is possible to realize the same stabilization of servo control as in the conventional case.

FIG. 4 is a schematic diagram showing a timing example of pulse emission of laser and sample hold used in the standby reproduction in this example.

In this embodiment, as shown in FIG. 4B, the laser diode 18 is driven to emit light based on the timing generated by the timing generation circuit 28. Here, the peak intensity P of the pulse-modulated light beam
It is necessary to set the beam intensity to 1 so that a sufficient amount of reflected light can be obtained by the photodetector 17 and the S / N ratio of the push-pull signal, the focus error signal, and the tracking error signal can be kept good.

In this example, the peak intensity P of the light beam is
1 is the beam intensity P11 of the laser during normal information reproduction
(See FIG. 7), which is the same value as 0.35 mW. On the other hand, the bottom intensity P2 of the pulse-modulated light beam is set to be less than the peak intensity P1 of the light beam. Here, as the bottom intensity P2 of the light beam decreases, it is possible to reduce the energy amount of the laser light with which the phase-change optical disc 10 is irradiated. In this example, the bottom intensity P2 of the light beam is set to 0.05 mW.

FIG. 4A shows the output signal from the RF amplifier 25 at this time. The output signal S1 is sampled and held by the sample and hold circuit 26. Signal S
Reference numeral 2 denotes a signal after the sample hold circuit 26 performs sample hold based on the timing generated by the timing generation circuit 28.

In order to keep the S / N ratio of the servo control signal high, the timing for sampling and holding the output signal S1 from the RF amplifier by the sample and hold circuit 26 must be set at the peak of the pulse modulation of the laser light intensity. . Therefore, the laser emission pulse width T2 needs to be equal to or longer than the time width required for the sample hold circuit 26 to hold the sample. In this example, the laser emission pulse width T2 is set to 150 nS.

On the other hand, the laser emission pulse period T1 is
It becomes a factor that determines the sampling accuracy of the output signal S1 from the RF amplifier 25, and also determines the lighting ratio of the laser, that is, the energy amount of the laser light with which the phase change type optical disk is irradiated, together with the emission pulse width T2 of the laser. It becomes an element to do.

Generally, several KH is provided in the servo control circuit 24.
A low-pass filter having a cutoff characteristic of about several tens of KHz from z is configured, and a focus drive signal, a tracking drive signal, etc. are obtained by using the push-pull signal, the focus error signal, and the tracking error signal after passing through the low pass filter. Is generated.

Therefore, the sampling frequency for sample-holding the output signal S1 from the RF amplifier 25 in the sample-hold circuit 26 needs to be equal to or higher than the cutoff frequency of the low-pass filter.

In view of the above, in this example, the laser emission pulse period T1 is set to 300 nS.

Hereinafter, the effect of suppressing crystallization of the recording mark portion in the case of performing the standby reproduction by using the optical recording / reproducing apparatus for the phase change type optical disk shown in this example will be described based on the measurement data.

FIG. 5 shows a case where the standby reproduction is repeatedly performed on the information recorded on the phase change type optical disk 10.
This is a measurement of the change in jitter of the reproduced signal. Specifically, the jitter between the digital signal train output from the binarization circuit 27 and the clock signal also output from the binarization circuit 27 is measured, and crystallized at the mark portion that should be in the amorphous state. In the case of occurrence of, it can be observed as deterioration of the jitter value.

As shown in FIG. 5, when the pulse intensity of the laser beam according to the present invention is pulse-modulated, the jitter value is not deteriorated, that is, the beam intensity of the laser beam is pulse-modulated. , The effect of suppressing crystallization of the mark portion has been proved. Further, as a result of the implementation of this example, the effect of the present invention on the stability of servo control has been confirmed.

As described above, in the optical recording / reproducing apparatus for the phase-change optical disk to which the present invention is applied, the energy of the laser light to be irradiated is pulse-modulated by modulating the light beam intensity of the laser light during standby reproduction. It is possible to suppress the temperature rise of the mark portion in the amorphous state by this, and to suppress the crystallization of the mark portion,
Furthermore, when the light beam intensity of the laser light is pulse-modulated, a stable servo operation can be realized by sampling and holding the signal required for servo control in synchronization with the peak portion of the pulse-modulated light beam intensity.

The present invention is not limited to the above-described embodiment, and various modifications and applications can be made without departing from the gist of the present invention.

[0069]

According to the present invention, the energy of the irradiated laser beam is reduced by pulse-modulating the light beam intensity of the laser beam during the standby reproduction, whereby the mark portion in the amorphous state is raised. The temperature can be suppressed and the crystallization of the mark part can be suppressed.

Further, when the light beam intensity of the laser light is pulse-modulated, the signal necessary for servo control is sampled and held in synchronization with the peak portion of the pulse-modulated light beam intensity, so that the conventional information reproduction can be performed. Equivalent S / N
The ratio is secured and stable servo operation can be realized.

As a result, it is possible to prevent the loss of recorded information or the deterioration of the quality of recorded information without sacrificing the stability of servo control.

[Brief description of drawings]

FIG. 1 is a block diagram of an example of an optical recording / reproducing apparatus to which the present invention is applied.

FIG. 2 is a cross-sectional view used to describe a phase change optical disc.

FIG. 3 is a block diagram used to describe an optical pickup.

FIG. 4 is a waveform diagram used for explaining an example of an optical recording / reproducing apparatus to which the present invention is applied.

FIG. 5 is a graph used for explaining an example of an optical recording / reproducing apparatus to which the present invention is applied.

FIG. 6 is a block diagram of an example of a conventional optical recording / reproducing device.

FIG. 7 is a waveform diagram used to describe an example of a conventional optical recording / reproducing apparatus.

[Explanation of symbols]

10 ... Optical disc, 17 ... Photo detector,
18 ... Laser diode, 19 ... Laser drive circuit, 20 ... Sled control circuit, 22 ... Sled mechanism, 23 ... Switch circuit, 24 ... Servo control circuit, 25 ... RF Amplifier, 26 ... Sample and hold circuit, 28 ... Timing generation circuit, 29 ...
..Data demodulation circuits, 30 ... Data modulation circuits, 31
... System controller, 32 ... Sled mechanism, 33 ... Optical pickup

Continued front page    F-term (reference) 5D090 AA01 BB05 CC04 DD03 EE16                       KK05                 5D118 BA01 BB07 BD01 BF05 CA11                       CA13 CB02 CD01                 5D119 AA31 BA01 BB04 DA05 DA13                       HA44                 5D789 AA31 BA01 BB04 DA05 DA13                       HA44

Claims (10)

[Claims] 1. An optical system for irradiating a laser beam modulated by a recording signal onto an optical disk at the time of writing, irradiating the optical disk with laser light at the time of reading, receiving the reflected light and outputting a reproduction signal of the optical disk. In an optical recording / reproducing apparatus having a pickup, a means for generating a servo error signal from the output of the optical pickup, and a means for performing servo control based on the servo error signal, the optical pickup without performing recording and reproduction. Means for pulse-modulating the light beam intensity from the optical pickup when performing the standby reproduction such that the track position on the optical disk is held and the servo error signal is transmitted when performing the standby reproduction. Servo control is performed by sampling and holding in synchronization with the pulse that modulates the light beam intensity. Optical recording and reproducing apparatus being characterized in that as and a stage. 2. The servo error signal is a tracking error signal, and when the standby reproduction is performed, the tracking error signal is sampled and held in synchronization with a pulse for modulating the light beam intensity from the optical pickup, The tracking servo control is performed.
The optical recording / reproducing apparatus according to item 1. 3. The servo error signal is a focus error signal, and when the standby reproduction is performed, the focus error signal is sampled and held in synchronization with a pulse for modulating the light beam intensity from the optical pickup, The optical recording / reproducing apparatus according to claim 1, wherein focus servo control is performed. 4. The servo error signal is a tracking error signal and a focus error signal, and a pulse for modulating the tracking beam error signal and the focus error signal to modulate the light beam intensity from the optical pickup during the standby reproduction. 2. The optical recording / reproducing apparatus according to claim 1, wherein the tracking servo control and the focus servo control are performed by sample-holding in synchronism with. 5. The optical recording / reproducing apparatus according to claim 1, wherein the readable and writable optical disk is a phase change optical disk. 6. At the time of writing, an optical disc is irradiated with laser light modulated by a recording signal from an optical pickup,
At the time of reading, laser light is emitted from the optical pickup to the optical disc, the reflected light is received by the optical pickup to output a reproduction signal of the optical disc, and a servo error signal is generated from the output of the optical pickup. A method for controlling an optical recording / reproducing apparatus having means for performing servo control based on a servo error signal, in which the optical pickup holds the track position on the optical disk and stands by without recording or reproducing. When reproducing, the light beam intensity from the optical pickup is pulse-modulated, and when performing the standby reproduction, the servo error signal is sample-held in synchronization with the pulse that modulates the light beam intensity to perform servo control. A method for controlling an optical recording / reproducing apparatus, characterized in that: 7. The servo error signal is a tracking error signal, and when the standby reproduction is performed, the tracking error signal is sampled and held in synchronization with a pulse for modulating the light beam intensity from the optical pickup, The tracking servo control is performed.
5. A method for controlling the optical recording / reproducing apparatus according to. 8. The servo error signal is a focus error signal, and when the standby reproduction is performed, the focus error signal is sampled and held in synchronization with a pulse for modulating the light beam intensity from the optical pickup, The control method of the optical recording / reproducing apparatus according to claim 6, wherein focus servo control is performed. 9. The servo error signal is a tracking error signal and a focus error signal, and a pulse for modulating the tracking beam error signal and the focus error signal to modulate the light beam intensity from the optical pickup during the standby reproduction. 7. The control method for an optical recording / reproducing apparatus according to claim 6, wherein the sample-holding is performed in synchronization with the tracking servo control and the focus servo control. 10. The control method for an optical recording / reproducing apparatus according to claim 6, wherein the readable / writable optical disk is a phase change optical disk.