JP2001176107A - Laser output control circuit for optical disk recoding/ reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser output control circuit used for an optical disk recording/reproducing device recording a signal on a disk by a laser beam emitted from an optical pickup. SOLUTION: When the recording operation of the signal on the disk is interrupted, the signal inputted to a servo control circuit 11 is switched from a sampling signal obtained from a sampling circuit 4 to a sample signal obtained from a sample signal hold circuit 12 by switching operation of a selection switch 7, and servo operation is started by the sample signal when recording operation is re-started.

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 laser light output from a laser element 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.

[0005] In a write-once optical disk recording / reproducing apparatus, when performing a switching operation from a reproducing state to a recording state, a switching speed corresponding to a servo operation of a servo circuit incorporated in a laser drive circuit is required. Then, as the recording speed of the signal on the disc increases, it is necessary to perform the switching operation from the reproduction state to the recording state in a short time,
In particular, when the recording operation is temporarily interrupted and then resumed, it is required that the recording operation with the optimal laser output be instantaneously resumed.

In order to perform such a switching operation in a short time, a method of increasing the gain of a servo circuit is adopted. However, a phenomenon called overshoot occurs in a recording waveform at the start of recording, and an optimum recording operation is performed. It takes a long time to start recording, and there is a problem that a recording signal is abnormal.

An object of the present invention is to provide a laser output control circuit of an optical disk recording / reproducing apparatus which solves the above problem.

[0008]

According to the present invention, there is provided a sampling circuit for sampling a recording level of a recording pulse signal obtained by monitoring a level of a laser beam output from a laser element and holding the level for a predetermined time. A servo control circuit for receiving a signal sampled by the sampling circuit and performing a servo operation for controlling a drive current supplied to the laser element based on the signal level; and a sampling signal output from the sampling circuit. A sample signal holding circuit for holding a level, and a selection switch for selecting a sampling signal output from the sampling circuit and a sample signal output from the sample signal holding circuit and inputting the selected signal to the servo control circuit, Write signal to disk When the operation is interrupted, a signal input to the servo control circuit by switching operation of the selection switch is obtained by the switched to sample signal from the sampling signal.

[0009]

FIG. 1 is a circuit diagram showing an embodiment of an optical disk recording / reproducing apparatus according to the present invention, and FIG. 2 is a waveform diagram for explaining the operation of the present invention.

In FIG. 1, reference numeral 1 denotes a laser diode which is incorporated in an optical pickup and irradiates a laser beam, and is connected so as to be driven by a current supplied from a laser driving circuit 2. I have. In such a circuit, during a recording operation,
The laser drive circuit 2 sends a pulse signal to the laser diode 1 as shown in FIG.
A pulse signal composed of R and a reproduction output VP is supplied.

Reference numeral 3 denotes a monitor signal input terminal to which a monitor signal obtained from a monitor diode (not shown) provided to monitor the laser light output from the laser diode 1 is input, and 4 denotes the laser diode. This is a sampling circuit for sampling the level of the recording output in the laser light output from the reference numeral 1, and based on the timing signal output from the timing signal generation circuit 5, as shown in FIG. It has the effect of sampling and maintaining that level during the playback output. The level holding operation of the recording output by the sampling circuit 4 is performed by a voltage holding operation by a capacitor (not shown) incorporated in the sampling circuit 4, and the holding time is the same as the interruption of the recording operation. If it is necessary to hold for a long time, it is a time that cannot be dealt with. In the figure, S is a sampling operation period, and H is a sampling holding period. The timing signal generating circuit 5 outputs an H (high) level signal when the optical disc recording / reproducing apparatus is in a recording operation state, and outputs an L (low) level signal when the recording operation state is interrupted. Output terminal 5A.

Reference numeral 6 denotes a buffer amplifier circuit to which an output signal of the sampling circuit 4 is input and which has a buffer function. Reference numeral 7 denotes an AND circuit 8 having one input terminal connected to the output terminal 5A of the timing signal generation circuit 5. Is a selection switch whose switching operation is controlled by the output signal of (1), and includes a movable terminal 7a, a fixed terminal 7b and a fixed terminal 7c connected to the output terminal of the buffer amplifier circuit 6. In such a configuration, when the level of the output signal of the AND circuit 8 is at the H level, it is set so that the state shown in FIG.

A system control circuit 9 has a control signal output terminal 9A connected to the other input terminal of the AND circuit 8, and is constituted by a microcomputer. A laser output setting circuit 10 which is controlled by a signal output from the system control circuit 9 and sets an output of laser light by setting a value of a drive current supplied from the laser drive circuit 2 to the laser diode 1; Reference numeral 11 denotes a servo control for performing a servo operation for controlling a value of a drive current supplied from the laser drive circuit 2 to the laser diode 1 based on a signal output from the laser output setting circuit 10 and a signal input through the selection switch 7. Circuit.

Reference numeral 12 denotes a sample signal holding circuit for holding, as a sample signal, the output signal of the buffer amplifier circuit 6, that is, the level of the sampling signal sampled by the sampling circuit 4, and its output terminal is a fixed terminal of the selection switch 7. 7c. 13
Is a comparison circuit having a negative input terminal connected to the output terminal of the buffer amplifier circuit 6 and a positive input terminal connected to the output terminal of the sample signal holding circuit 12. The output signal is It is configured to be input to the system control circuit 9.

In such a configuration, when switching to a state in which a data signal is recorded in a signal recording area provided on a disk, an H-level signal is output to an output terminal 5A of the timing signal generation circuit 5 and the system is switched. The control circuit 9 is configured to output an H level signal to a control signal output terminal 9A. The level of the signal output from the control signal output terminal 9A of the system control circuit 9 changes from H level to L level when the selection switch 7 is switched to the opposite side of the state shown in the figure.
When the level of the output signal of the comparison circuit 13 is inverted when the level of the input signal, that is, the level of the sampling signal becomes equal to the level of the sample signal, the output level is inverted from the L level to the H level. It is configured to be.

In such a configuration, it is possible to obtain data obtained by performing a test signal recording operation in a test writing area provided on the inner peripheral side of the disk, that is, to obtain an optimum laser output for performing the recording operation. The possible data is supplied as a control signal from the system control circuit 9 to the laser output setting circuit 10, and a control signal capable of obtaining an optimum laser output is supplied from the laser output setting circuit 10 to the servo control circuit 11. Since the setting operation of the optimum laser output can be performed by utilizing the conventional technology, the description is omitted.

When a data signal is recorded in the recording area of the disk, an H-level signal is output to the output terminal 5A of the timing signal generation circuit 5 and a control signal output terminal provided in the system control circuit 9. 9A
Is output at the H level, the level of the output signal of the AND circuit 8 becomes H level. As a result, the selection switch 7 is in the state shown, and when in this state,
A pulse signal having a waveform shown in FIG. 2 is output from the laser drive circuit 2 to the laser diode 1.

In the state where such a recording operation is being performed, a sampling operation and a sampling holding operation for the recording output by the sampling circuit 4 are performed based on the timing signal output from the timing signal generating handrail 5, The held sampling signal is input to the servo control circuit 11 through the buffer amplifier circuit 6 and the selection switch 7. When the sampling signal is input to the servo control circuit 11 in this manner, the servo control circuit 11 performs a servo control operation based on the control signal output from the laser output setting circuit 10 and the sampling signal, and outputs the servo signal. It is applied to the laser drive circuit 2. As a result, a drive signal for obtaining an optimum laser output is supplied from the laser drive circuit 2 to the laser diode 1, so that the signal recording operation on the disk can be performed with the optimum laser output. .

While such a recording operation is being performed,
A monitor signal obtained from a monitoring diode provided to monitor the laser light emitted from the laser diode 1 is input to a monitor signal input terminal 3, and a signal obtained by sampling the input signal and a laser output setting circuit 10. Since the output control signal is input to the servo control circuit 11 and controlled, a control operation for maintaining the laser output in an optimum state, that is, a so-called servo operation is performed. Then, in the state where such a recording operation is being performed, a signal having the same level as the level of the signal sampled by the sampling circuit 4 is held in the sample signal holding circuit 12 as a sample signal by the control operation of the system control circuit 9. In state.

As described above, the operation of recording a signal on the disk is performed. Next, the operation when the recording operation is interrupted will be described. When a data signal, which is a recording signal input from a computer device or the like, is interrupted, there is no signal to be recorded on the disk, and the operation of recording a signal on the disk is interrupted.

When the recording operation on the disk is interrupted, the level of the signal output to the output terminal 5A of the timing signal generation circuit 5 is inverted from H level to L level. As a result, since the output signal of the AND circuit 8 is inverted from the H level to the L level, the selection switch 7 is switched to the opposite side of the state shown. When the selection switch 7 is switched to the opposite side of the illustrated state, the signal input to the servo control circuit 11 is switched from the sampling signal output from the buffer amplifier circuit 6 to the sample signal output from the sample signal holding circuit 12. .

When the recording operation is interrupted, the above-described switching operation is performed. However, since the recording operation is not performed, the driving current supplied from the laser driving circuit 2 to the laser diode 1 is not a recording output but a reproduction output. Become. When a predetermined time elapses after the switching operation is performed, the level of the signal output to the control signal output terminal 9A of the system control circuit 9 is inverted from the H level to the L level.

In such a state, a data signal, which is a recording signal input from a computer device or the like, is stored in a buffer memory provided for temporarily storing the recording signal, and the amount of data is stored in the buffer memory. When the recording operation reaches an amount at which the recording operation can be performed, the operation of the system control circuit 9 switches to a state of recording a signal on the disk. When the switching operation for restarting the recording operation is performed, first, the timing signal generation circuit 5
Of the output terminal 5A is inverted from L level to H level. Output terminal 5A of the timing signal generation circuit 5
Even if a high-level signal output from the AND circuit 8 is input to the AND circuit 8, since the level of the other input signal of the AND circuit 8 is at the L level, the output signal of the AND circuit 8 is not inverted to the H level. Absent.

Therefore, the signal input to the servo control circuit 11 when the recording operation is restarted becomes a sample signal which is an output of the sample signal holding circuit 12, and is output from the sample signal and the laser output setting circuit 10. The recording current supplied from the laser drive circuit 2 to the laser diode 1 is set by the servo control operation performed based on the signal. When the recording operation is restarted in this way, the sample signal held by the sample signal holding circuit 12, that is, the signal of the level sampled by the sampling circuit 4 before the interruption of the recording operation is input to the servo control circuit 11. Therefore, the magnitude of the recording current supplied from the laser drive circuit 2 to the laser diode 1 can be set to a value at which a good recording operation can be immediately performed. As a result of such an operation, the recording operation can be restarted instantaneously and in a favorable state.

The recording operation is resumed by the above-described operation. When the recording operation is started, the sampling operation by the sampling circuit 4 is started. Input terminal. Then, the +
The signal from the sample signal holding circuit 12, that is, the sample signal is input to the input terminal on the negative side, and when the level of the sampled signal input to the input terminal on the negative side is equal to the level of the sample signal, the comparison is performed. The level of the signal output to the output terminal of the circuit 13 is inverted, and the signal is input to the system control circuit 9. When such a signal is input to the system control circuit 9, the signal output to the control signal output terminal 9A provided in the system control circuit 9 is inverted from L level to H level.

When the signal output to the control signal output terminal 9A of the system control circuit 9 is inverted from the L level to the H level, both the levels of the input signals of the AND circuit 8 become H.
Therefore, the level of the output signal is inverted from L level to H level. As a result, the selection switch 7
Will be switched to the illustrated state. When the selection switch 7 is switched to the illustrated state, the sampling signal output from the sampling circuit 4 is input to the servo control circuit 11, so that a normal recording operation is performed. The switching operation to the state where the normal recording operation is performed is performed when the level of the sampling signal obtained from the sampling circuit 4 and the level of the sample signal which is the output signal of the sample signal holding circuit 12 become the same. The effect on the servo control circuit 11 during switching can be minimized.

[0027]

According to the present invention, a sampling circuit for sampling a recording level of a recording pulse signal obtained by monitoring the level of a laser beam output from a laser element and holding the level for a predetermined time, and the sampling circuit And a servo control circuit that performs a servo operation for controlling a drive current supplied to the laser element based on the signal level, and holds a level of a sampling signal output from the sampling circuit. A sample signal holding circuit; and a selection switch for selecting a sampling signal output from the sampling circuit and a sample signal output from the sample signal holding circuit and inputting the selected signal to the servo control circuit. Recording operation is interrupted In this case, the signal input to the servo control circuit is switched from the sampling signal to the sample signal by the switching operation of the selection switch, and the servo operation is started by the sample signal when the recording operation is restarted. Can be quickly performed. Thus, according to the present invention,
After the recording operation is interrupted, the recording operation of the connection portion can be performed without any trouble in the case of performing the recording restart operation of recording the next signal following the signal recorded so far.

According to the present invention, when the level of the sampling signal output from the sampling circuit becomes equal to the level of the sample signal after the interruption of the recording operation is released, the selection switch is output from the sampling circuit. Since the sampling signal is switched to the state of being input to the servo control circuit, the effect on the servo control circuit when the selection switch is switched can be minimized, and the recording characteristics can be improved. ing.

[Brief description of the drawings]

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

FIG. 2 is a waveform chart for explaining the operation of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 laser diode 2 laser drive circuit 4 sampling circuit 5 timing signal generation circuit 7 selection switch 9 system control circuit 10 laser output setting circuit 11 servo control circuit 12 sample signal holding circuit

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Akira Tsukihashi 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term in Sanyo Electric Co., Ltd. 5D090 AA01 BB03 CC01 KK03 5D118 AA11 BA01 BB03 BF07 CA02 5D119 AA24 BA01 HA06 HA12 HA62

Claims (2)

[Claims] 1. An optical disk recording / reproducing apparatus configured to record a signal on a disk by a laser beam, wherein a recording level of a recording pulse signal obtained by monitoring a level of a laser beam output from a laser element is sampled. A sampling circuit for holding the level for a predetermined time and a servo control circuit for receiving a signal sampled by the sampling circuit and performing a servo operation for controlling a drive current supplied to the laser element based on the signal level A sampling signal holding circuit for holding a level of a sampling signal output from the sampling circuit; a sampling signal output from the sampling circuit and a sample signal output from the sample signal holding circuit; control And a selection switch for inputting the signal to the circuit. When the operation of recording the signal on the disk is interrupted, the signal input to the servo control circuit is switched from a sampling signal to a sample signal by the switching operation of the selection switch, and the recording operation is performed. A laser output control circuit for an optical disk recording / reproducing apparatus, wherein a servo operation is started by a sample signal at the time of restarting. 2. After the interruption of the recording operation is released, when the level of the sampling signal output from the sampling circuit becomes equal to the level of the sample signal, the selection switch is switched to the sampling signal output from the sampling circuit. 2. The laser output control circuit according to claim 1, wherein the laser output control circuit is switched to a state for inputting to a servo control circuit.