JP2003346374A - Laser output control circuit of optical disk recording/ reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser output control circuit for controlling outputs of laser lights irradiated from an optical pickup. <P>SOLUTION: While supplying a driving voltage based on the driving data for measurement instead of a driving voltage from a servo circuit to a laser diode 1, a relationship between the driving voltage for the measurement and a monitor signal is obtained based on the monitor signal acquired from a monitoring diode 3 before executing a recording operation, a level of the monitor signal acquired from the monitoring diode 3 during the recording operation, when the recording operation is restarted after a recording interruption, a driving voltage based on the level of the monitor signal stored into a memory circuit 10 at the time of the recording interruption is supplied to the laser diode 1 instead of the driving voltage from the servo circuit, and when the recording operation is restarted, the driving voltage from the servo circuit is supplied to the laser diode 1. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc recording apparatus which records a signal on a disc by a laser beam emitted from an optical pickup and reproduces a signal recorded on the disc by the laser beam. It relates to a playback device.

[0002]

2. Description of the Related Art Disk players which read signals recorded on a disk using an optical pickup have become widespread. Recently, in addition to a reproduction function, a laser beam emitted from the optical pickup has been used. 2. Description of the Related Art An optical disk recording / reproducing apparatus configured to record a signal on a disk has been commercialized.

In such an optical disk recording / reproducing apparatus, pits are formed on a disk by a laser beam. However, if the output level of the laser beam is not optimal, the pit shape may be too large. It will be too small. Therefore, a disk used in such an optical disk recording / reproducing apparatus is provided with a test writing area on the innermost side, and after recording a signal in the test writing area, reproducing the signal, and detecting the reproduced signal. The laser output for recording is set according to the method described in JP-A-6-7628.
No. 8 discloses a technique disclosed in Japanese Patent Publication No.

[0004]

The operation of recording a signal on a disk is performed by alternately switching the output level of a laser beam output from a laser diode between a recording level and a reproduction level. That is, the recording is performed by forming pits on a signal track provided on the disk by using a laser beam for recording output, and the size of the pits is set to a specified size. The recording operation of such a signal is performed by rotating the disk at a predetermined constant linear velocity, but recently, the recording operation is performed with the linear velocity during the recording operation being several times the predetermined velocity. An optical disk recording / reproducing device capable of performing such operations has been commercialized.

When the recording operation on the disk is performed at a constant linear velocity, there is a characteristic that the rotation speed on the inner peripheral side is higher than that on the outer peripheral side. Then, on the inner peripheral side of the disk, for example, a linear velocity of 16 at
Although the recording operation can be performed at twice the linear velocity,
It is difficult to perform a recording operation at a constant linear velocity of 0 or 24 times. For this reason, recently, there has been developed a technology that enables a recording operation to be performed in a short time by performing a recording operation from an inner circumference to an outer circumference while rotating the disk at a constant rotation speed, that is, a constant angular velocity. Is being developed.

When the recording speed on a disk is increased, a phenomenon called a buffer underrun occurs, in which the data amount of a data signal output from a computer device as a host device becomes insufficient. Thus, a technique has been developed in which, when a buffer underrun state occurs, a recording operation is temporarily interrupted and then the recording operation is restarted from the recording interruption position so that a buffer underrun error does not occur.

Although the occurrence of a buffer underrun error can be prevented by performing the recording resuming operation, the signal to be recorded on the disk must be recorded continuously by the recording resuming operation. It is necessary to accurately control the laser output for performing the recording operation.

An object of the present invention is to provide a control circuit suitable for performing such a laser output control operation.

[0009]

SUMMARY OF THE INVENTION The present invention provides a laser diode for irradiating a laser beam for recording a signal on a disk, and a monitoring diode provided to monitor the level of the laser beam radiated from the laser diode. A recording output setting circuit for outputting a reference signal for obtaining a laser output suitable for performing a recording operation, and comparing a reference signal output from the recording output setting circuit with a monitor signal obtained from the monitoring diode. A servo circuit for controlling the level of the drive voltage supplied to the laser diode, and supplies a drive voltage based on the measurement drive data to the laser diode in place of the drive voltage from the servo circuit, and the monitor circuit. The drive voltage and the monitor are determined based on the monitor signal obtained from the diode. Before performing the recording operation to determine the relationship with the level of the monitor signal, detect the level of the monitor signal obtained from the monitoring diode during the recording operation, provided a memory circuit that stores the level of the detected monitor signal, At the time of recording restart after recording interruption, a driving voltage based on the level of the monitor signal at the time of recording interruption stored in the memory circuit was supplied to the laser diode instead of the driving voltage from the servo circuit, and the recording operation was resumed. At this time, the driving voltage from the servo circuit is supplied to the laser diode.

[0010]

FIG. 1 is a circuit diagram showing an embodiment of an optical disk recording / reproducing apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes a laser diode that is incorporated in an optical pickup and emits laser light, and is connected so as to be driven by a current supplied from a laser drive circuit 2. In such a circuit, during a recording operation,
The laser drive circuit 2 supplies a pulse signal, that is, a pulse signal composed of a recording output level and a reproduction output level, to the laser diode 1.

Reference numeral 3 denotes a monitor diode provided to monitor the level of laser light output from the laser diode 1, and 4 denotes a monitor signal amplifier circuit to which a monitor signal obtained from the monitor diode 3 is input. Yes, it has the function of amplifying the monitor signal.

Reference numeral 5 denotes a recording / reproducing operation of a test signal in a test writing area provided on a disk and a laser output set by calculation based on a relational expression between a recording linear velocity and a laser output. This is a recording output setting circuit that outputs a reference signal suitable for the recording linear velocity based on stored data. The reference signal input terminal 6 is connected to the output terminal of the monitor signal amplifier circuit 4 and the reference signal input terminal is connected to the output terminal of the recording output setting circuit 5. A capacitor 7 and a resistor 8 are connected in parallel between an output terminal and a comparison signal input terminal.

Reference numeral 9 denotes a control circuit for performing various control operations of the optical disk recording / reproducing apparatus. The recording output setting circuit 5 performs a control operation for outputting a reference signal capable of obtaining an optimum laser output. Reference numeral 10 denotes a memory circuit whose operation is controlled by the control circuit 9, and is configured to store various data.

Reference numeral 11 denotes a control switch whose switching operation is controlled by the control circuit 7. The control switch 11 is connected to a movable terminal 11a connected to an input terminal of the laser drive circuit 2 and to an output terminal of the comparison circuit 6. First fixed terminal 11
b and 11 c connected to a recording start voltage output terminal 9 R provided in the control circuit 9.

In such a configuration, the recording operation of the test signal is performed in the test writing area provided on the inner peripheral side of the disk and the reproducing operation of the recorded test signal is performed so that the recording linear velocity, for example, the inner peripheral side is improved. At which the laser output can be optimally obtained for performing the recording operation at the recording start position, and the recording output setting circuit 5 changes the recording position as it moves in the outer peripheral direction of the disk based on the data. It is configured to output a reference signal corresponding to the linear velocity. Such a reference signal is configured to be calculated based on a preset relational expression between the recording speed and the laser output.

In such a configuration, a buffer underrun state occurs when the amount of data signals output from the computer device is insufficient. In such a state, the recording operation on the disk is temporarily interrupted and the data signal is temporarily stopped. The recording operation can be resumed from the recording interruption position when the amount of. Such a recording interruption / resumption operation can be performed by using a well-known technique, and a description thereof will be omitted.

When the data signal is recorded in the recording area of the disk, the control switch 11 is in the state shown in the figure, and the laser drive circuit 2 outputs the pulse signal, that is, the recording output level and the reproduction output level. The configured pulse signal is output to the laser diode 1. When the recording operation is performed, the monitor signal amplified by the monitor signal amplifier circuit 4 is input to the comparison signal input terminal of the comparison circuit 6.

When the recording operation is performed as described above, the monitor signal amplified by the monitor signal amplifier circuit 4 is input to the comparison signal input terminal of the comparison circuit 6,
The signal is compared with the reference signal output from the recording output setting circuit 5. When the laser output for performing the recording operation is controlled, the period of the recording output level is sampled. The configuration is such that the monitor signal during the period is input to the comparison signal input terminal of the comparison circuit 6.

The operation of comparing the monitor signal of the recording output level inputted to the comparison signal input terminal of the comparison circuit 6 with the reference signal which is the output signal of the recording output setting circuit 5 inputted to the reference signal input terminal. Is performed, and the comparison output signal is supplied to the laser drive circuit 2 via the control switch 11, so that the control operation for setting the recording output of the drive signal supplied to the laser diode 1 to an optimum level is performed. become. That is, after a monitor signal obtained from a monitoring diode 3 provided to monitor a laser beam emitted from the laser diode 1 is amplified by a monitor signal amplifier circuit 4, the monitor signal is input to a comparison signal input terminal of a comparison circuit 6. Then, the operation of comparing the input signal with the reference signal output from the recording output setting circuit 5 by the comparison circuit 6 is always performed. Since the compared signal is supplied to the laser drive circuit 2,
Control operation to keep the laser output at the optimal state,
A so-called servo operation is performed. A servo circuit for performing such a servo operation includes a monitoring diode 3, a monitor signal amplifying circuit 4, a recording output setting circuit 5, and a comparing circuit 6.

Next, the operation of setting the laser output at the time of resuming the recording which is the gist of the present invention will be described. When recording a data signal on a disk that rotates at a constant angular velocity, it is necessary to change the laser output because the recording linear velocity gradually increases as the recording position moves in the outer peripheral direction. As described above, the operation of recording and reproducing the test signal in the test writing area and the calculation operation based on the relational expression set in advance are performed. The setting of the drive data used in the recording interruption / resumption operation will be described.

The operation for setting the driving data is performed in a state where the control switch 11 is switched to the opposite side of the state shown in the figure. For example, the laser drive circuit 2 outputs a drive voltage based on measurement drive data capable of outputting a laser beam of 20% of the rated output that the laser diode 1 can emit. As a result, a laser beam of about 20% of the rated output is emitted from the laser diode 1, so that a monitor signal corresponding to the light emission amount is obtained from the monitoring diode 3 irradiated with the laser beam. The monitor signal obtained from the monitor diode 3 is amplified by the monitor signal amplifier circuit 4 and then input to the control circuit 9. Therefore, in such a state, the measurement data corresponding to the drive voltage supplied to the laser diode 1 and the level of the monitor signal can be detected, and the data is stored in the memory circuit 10.

When the measurement storage operation is completed, the driving voltage based on the measurement driving data capable of outputting a laser beam of 80% of the rated output that can be irradiated by the laser diode 1 is then applied to the laser driving circuit 2. Output more. As a result, a laser beam of about 80% of the rated output is emitted from the laser diode 1, so that a monitor signal corresponding to the light emission amount is obtained from the monitor diode 3 irradiated with the laser beam. The monitor signal obtained from the monitor diode 3 is amplified by the monitor signal amplifier circuit 4 and then input to the control circuit 9. Therefore, in such a state, the laser diode 1
And the measurement data corresponding to the level of the drive voltage and the monitor signal supplied to the memory circuit 10, and the data is stored in the memory circuit 10.

By the above-described measuring operation, the drive voltage at the time of low output (20% of the rating) and the driving voltage at the time of high output (80% of the rating) and data based on the level of the monitor signal corresponding to each output are stored in the memory circuit 10. Therefore, an approximate expression for calculating the relationship between the drive voltage and the level of the monitor signal can be obtained from these data. Further, when performing such a measurement operation, the level of the laser light emitted from the laser diode 1 reaches a level for performing the recording operation, and thus a signal is recorded on the disk in a focused state. Accordingly, in the state where such a setting operation is performed, the laser light emitted from the laser diode 1 is not focused on the signal surface of the disk by the control operation of the control circuit 9 to the pickup control circuit (not shown), that is, the non-focus A control operation for bringing into a focus state is performed.

As described above, the setting and adjustment of the laser output before the start of the recording operation and the like are performed. Next, the operation of this embodiment will be described. When the recording operation is being performed, the control switch 11 is in the state shown in the figure, and the recording output setting circuit 5 outputs a reference signal suitable for the linear velocity of the recording position on the disk. In the state of being input to the terminal. A monitor signal obtained from a monitoring diode 3 provided to monitor the level of laser light emitted from the laser diode 1 is amplified by a monitor signal amplifier circuit 4 and then input to a comparison signal input terminal of the comparison circuit 6. It is in the state that was done. Accordingly, a drive voltage controlled by a servo operation based on the reference signal output from the recording output setting circuit 5 is supplied from the laser driving circuit 2 to the laser diode 1, so that a laser output suitable for the recording position on the disk is provided. Thus, a recording operation can be performed.

As described above, a laser beam having an output suitable for the linear velocity of the recording position is emitted from the laser diode 1, but a monitor signal corresponding to the irradiation level is always input to the control circuit 9. If the buffer underrun state occurs during the recording operation state, the recording operation on the disk is interrupted. When the interruption operation is performed, the level of the monitor signal is stored in the memory circuit 10.
Then, when the buffer underrun state is resolved, a control operation for restarting the signal recording operation is performed so as to be continuous with the signal recorded before the recording was interrupted. Such a control operation is performed by performing a reproduction operation of a signal recorded on the disk before the interruption and performing a synchronization process between a synchronization signal obtained from the reproduction signal and a synchronization signal for recording. The switching operation to the recording state is performed at the interruption position.

The control operation for resuming the recording is, first, a control operation for outputting a drive voltage based on the level of the monitor signal stored by the above-described operation to the recording start voltage output terminal 9R provided in the control circuit 9. Done. That is,
A drive voltage corresponding to the level of the monitor signal stored in the memory circuit 10 when the recording is interrupted is calculated based on an approximate expression indicating the relationship between the drive voltage measured before the start of recording and the level of the monitor signal. Is output to the recording start voltage output terminal 9R.

When such a control operation is performed, a synchronization signal immediately before a recording restart, for example, a synchronization signal immediately before a synchronization signal incorporated in a block constituting a recording signal to be recorded by the recording restart, that is, a last synchronization signal before the recording is interrupted. When the synchronization signal recorded in the control switch 11 is detected, the operation of switching the control switch 11 to the opposite side of the illustrated state is performed.

After the switching operation is performed, when the laser beam emitted from the laser diode 1 reaches the recording restart position, the operation of switching each circuit constituting the optical disk recording / reproducing apparatus to the state of performing the recording operation is performed. Will be When the switching to the recording operation state is performed in this manner, the laser drive circuit 2 supplies the drive voltage output to the recording start voltage output terminal 9R provided in the control circuit 9, that is, the linear velocity at the recording start position. When the recording is started, a driving signal for obtaining a laser output for performing an optimum recording operation for the laser diode 1 is supplied from the laser driving circuit 2 at the start of recording. Become.

When the recording operation is switched to the recording operation state and the recording operation is started, the control switch 11 is immediately switched to the state shown in the figure. When the control switch 11 is switched to the state shown, the drive voltage obtained from the comparison circuit 6 is supplied to the laser drive circuit 2 via the control switch 11. The laser diode 1 emits light by the drive current based on the drive voltage output to the recording start voltage output terminal 9R provided in the control circuit 9, and the drive voltage based on the emission output is output to the output terminal of the comparison circuit 6. Since the drive voltage obtained from the comparison circuit 6 by the switching of the control switch 11 is supplied to the laser drive circuit 2, the light emission output does not change. When the recording operation is restarted by the above-described operation, the driving current supplied to the laser diode 1 becomes a current value corresponding to the reference signal output from the recording output setting circuit 5, so that the laser diode 1 The output of the emitted laser light is set to an optimum level for performing the recording operation at the recording start position.

After the above-described switching operation is performed, a control operation based on the monitor signal obtained from the monitoring diode 3, that is, a servo operation is performed, and an output adjustment operation of the laser light emitted from the laser diode 1 is performed. Will be When the switching operation to the recording operation state is performed as described above, the output of the laser light emitted from the laser diode 1 is started from an optimum level, so that the servo operation for controlling the output operation of the laser light is started immediately. Can be done. Therefore, the switching operation to the recording operation state can be performed in a short time, and the recording restart operation after the recording interruption can be started from the recording interruption position on the disk. Therefore, the signal write operation can be accurately performed so as to be continuous with the signal recorded on the disk before the recording is interrupted.

In this embodiment, the case where data for generating laser light of 20% and 80% of the rated output of the laser diode is used as the measurement drive data has been described, but the data is limited. However, there is no problem as long as the data can obtain an accurate approximate expression representing the relationship between the drive voltage and the level of the monitor signal.

[0032]

According to the present invention, there is provided a laser diode for irradiating a laser beam for recording a signal on a disk, a monitoring diode provided for monitoring the level of the laser beam emitted from the laser diode, and a recording operation. A recording output setting circuit for outputting a reference signal for obtaining a laser output suitable for performing the laser output, and comparing the reference signal output from the recording output setting circuit with a monitor signal obtained from the monitoring diode. A servo circuit that controls the level of the drive voltage supplied to the diode, and supplies a drive voltage based on the measurement drive data to the laser diode instead of the drive voltage from the servo circuit, and obtains the drive voltage from the monitor diode. Based on the monitor signal, the drive voltage and the monitor signal A memory circuit that detects the level of the monitor signal obtained from the monitoring diode during the recording operation and stores the detected level of the monitor signal. When recording is resumed, a drive voltage based on the level of a monitor signal at the time of recording interruption stored in the memory circuit is supplied to the laser diode instead of the drive voltage from the servo circuit, and when the recording operation is resumed, Since the drive voltage from the servo circuit is supplied to the laser diode, the laser output at the time of resuming recording can be set to an optimum value. Therefore, according to the present invention, in a state where a signal is recorded on a disk that rotates at a constant angular velocity, even if the recording operation is interrupted and resumed, the next signal follows the previously recorded signal. Can be performed without any trouble.

Further, according to the present invention, the operation for obtaining the relationship between the drive voltage and the level of the monitor signal is performed in an out-of-focus state, so that the signal recorded on the disk is erased. The adverse effects can be prevented.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of an optical disk recording / reproducing apparatus according to the present invention.

[Explanation of symbols]

1 Laser diode 2 Laser drive circuit 3 Monitor diode 4 Monitor signal amplifier circuit 5 Recording output setting circuit 6 Comparison circuit 9 Control circuit 10. Memory circuit 11 Control switch

   ────────────────────────────────────────────────── ─── Continuation of front page    F term (reference) 5D090 AA01 BB03 BB04 CC01 CC04                       CC16 DD03 EE01 EE11 FF09                       HH02 JJ12 KK03 LL08                 5D119 AA23 AA31 BA01 BB02 BB03                       DA01 DA05 FA05 HA03 HA08                       HA12 HA19 HA27 HA28 HA45                       HA68                 5D789 AA23 AA31 BA01 BB02 BB03                       DA01 DA05 FA05 HA03 HA08                       HA12 HA19 HA27 HA28 HA45                       HA68

Claims (3)

[Claims] An optical disk recording / reproducing apparatus configured to record a signal on a disk that is driven to rotate at a constant angular velocity and to perform an interruption / resumption operation of a recording operation in a recording operation state. A laser diode for irradiating a laser beam to be recorded, a monitoring diode provided to monitor the level of the laser beam emitted from the laser diode, and a reference signal for obtaining a laser output suitable for performing a recording operation. A recording output setting circuit for outputting, and a servo for controlling a level of a driving voltage supplied to the laser diode by comparing a reference signal output from the recording output setting circuit with a monitor signal obtained from the monitoring diode. And a driving voltage from the servo circuit. The drive voltage based on the drive data for measurement is supplied to the laser diode, and the relationship between the drive voltage and the level of the monitor signal is obtained before the recording operation is performed based on the monitor signal obtained from the monitoring diode. A memory circuit for detecting a level of a monitor signal obtained from the monitoring diode and storing the detected level of the monitor signal is provided, and when recording is resumed after recording is interrupted, the memory is replaced with a drive voltage from the servo circuit. A drive voltage based on the level of the monitor signal at the time of recording interruption stored in the circuit is supplied to the laser diode, and when the recording operation is restarted,
A laser output control circuit for an optical disk recording / reproducing apparatus, wherein a drive voltage from the servo circuit is supplied to a laser diode. 2. The laser output control circuit according to claim 1, wherein the operation for obtaining the relationship between the drive voltage and the level of the monitor signal is performed in an out-of-focus state. 3. The drive data for measurement for obtaining a relationship between a drive voltage and a level of a monitor signal is two different data of a low-level drive voltage and a high-level drive voltage. Laser output control circuit.