JP2003099935A - Optical disk recording device and method for controlling laser power - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the fluctuation of optimum recording power generated when recording power is controlled at the restart of recording in a function for dealing with a buffer underrun in an optical disk recording device. SOLUTION: A recording power controller is switched from an APC (Automatic Power Control) circuit 6 to a D/A converter (laser power setting part 10) to restart recording at a recording power set value A obtained immediately before the break of recording when the recording is restarted, and then switched to a normal APC after monitoring the set output of controlling the APC circuit 6 after the restart to confirm the monitor value B that equals to the recording power set value A. An immediate power startup can be done by the recording power setting with the laser power setting part 10 when the recording is restarted, and the power fluctuation of the power when switching is suppressed by monitoring the recording power control voltage of the APC circuit 6 to control the timing of the switching to the analog APC circuit 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk recording apparatus and a recording method for recording information on a recording medium by using an optical head, and more particularly to a recording stop and recording restart function at the time of restarting the recording. The present invention relates to an optical disk device and a laser power control method for stabilizing the laser drive.

[0002]

2. Description of the Related Art In recent years, due to high-speed recording in a CD-R / RW drive, establishment of a buffer underrun error caused by a higher recording speed than a data transfer speed is increasing. As a countermeasure against this buffer underrun, a buffer underrun is detected in advance, recording is suspended, and it is confirmed that a certain amount of data has been accumulated in the buffer and then recording is restarted. A drive equipped with an encoder having a recording function that enables data reproduction even at a recording joint by synchronizing with the data before the interruption at the time of resuming recording is becoming mainstream. The buffer underrun is detected, recording is resumed, recording data is connected, recording is restarted, etc.
/ W (firmware).

In using this function, one important point is the laser power control of the optical head which actually records on the optical disk. Generally, there is a laser and a laser driver that drives the laser, and a front monitor (P
D: Automatic output control circuit (hereinafter referred to as APC) that controls the laser power constantly based on the signal from the photodiode.
(Automatic Power Control) circuit).

The APC circuit is generally composed of an analog circuit, but it may be controlled by a microprocessor as firmware.

In the APC control at the time of the recording pause in the buffer underrun support function and the recording restart in the recording restart function, the rise of the laser is accelerated and the power setting at the recording restart is set to the same value as before the recording pause. Is required.

Further, in the APC circuit, the light emission output of the laser is received by the front monitor, and the laser power is controlled to a certain target value: optimum value by loop control by the APC circuit based on the signal from the front monitor.

The APC circuit has a loop filter in order to prevent overpower due to a transient reaction when the power is turned on. The loop filter has a certain time constant, and it takes some time for the laser output to reach the target value.

In the optical disk recording apparatus having the recording pause and the recording restart function, the recording of the joint portion of the recording at the time of the recording stop / restart makes an insufficient recording area by the delay time. Even if the connection timing of the recording signals in the encoder 8 can be perfectly processed, a slight omission occurs at the connection due to the characteristics of the APC circuit 6.

In reading the optical disc 1 recorded in this way, if there is a defect within the range of error correction or the like, no problem occurs in recording and reproduction. As the recording speed increases, the amount of recorded data within the delay time of the rise due to the loop filter time constant increases, and the increase of this missing data increases the possibility of a read error.

In addition to the optical output power set value input terminal, the laser driver 4 has a terminal for controlling whether or not to output the set power, and even if the power set value is input, this control switch is turned on. Unless otherwise, the laser 3 does not output a light output.

Therefore, it is conceivable to set the power setting value before the recording is stopped and restart the recording in the power control at the time of restarting the recording (for example, Japanese Patent Laid-Open No. 2000-2000).
No. 149263A).

[0012]

However, in the case of actually giving the initial value, it cannot be realized only by the structure of the normal analog APC circuit. The reason can be realized by a firmware-controlled APC such as a microprocessor, but the APC in the firmware has a problem that the load of the firmware becomes heavy, and in a general optical disc recording device, the APC in an analog circuit is Mainstream.

However, in the analog APC circuit configuration, even if the initial value at the time of resuming recording can be set by another circuit before the recording is stopped, there is a problem that power fluctuation occurs when switching from the initial value circuit to the APC circuit.

Although it is possible to hold the analog APC circuit at the final stage as a countermeasure, the analog APC circuit
Due to the characteristics of the PC circuit, the held value decreases with the lapse of time, and there is a problem in that there is a difference in the laser power when the recording interruption is resumed.

[0015]

The laser power control according to the present invention is characterized in that an analog switch and a laser power setting section are separately provided in an analog APC circuit generally used in an optical disk recording apparatus. Further, the output of the APC circuit during laser power control by the laser power setting unit is monitored to finely adjust the power setting of the laser power setting unit. The timing of switching from the laser power setting unit to the APC circuit It is characterized by controlling.

This laser power control system makes it possible to properly and suppress fluctuations in laser power during the recent buffer underrun support function, and realizes stable laser power control at the time of resuming interruption of recording. It is a thing.

Specifically, an optical head for recording / reading data by irradiating an optical disc with a laser beam, an automatic output control circuit for controlling the output of the laser beam emitted by the optical head at a constant value, and an automatic output control. A setting unit that sets the output of the laser light separately from the circuit, a monitor unit that monitors the output value of the automatic output control circuit and the setting unit, a switching circuit that switches between the automatic output control circuit and the setting unit, and from the monitor unit It is characterized in that it is provided with a control means for instructing the optimum value to the setting section based on the obtained result, and has a recording stop and restart function.

Further, the optical disc may be a write-once type optical disc using a dye as a recording film or a write-once type optical disc using a phase change film as a recording film.

Further, in the laser power control method by the optical disk recording apparatus of the present invention, the control means monitors the set value of the automatic output control circuit during recording to store the set value immediately before the recording is interrupted and set when the recording is restarted. The section is characterized by setting a set value immediately before the interruption of recording and outputting a laser beam.

After the recording is resumed, the output value of the automatic output control circuit is monitored by the monitor section, and the control means compares the set value with the output of the automatic output control circuit to adjust the set value. It is characterized in that the switching timing from the laser light output control to the laser light output control by the automatic output control circuit is controlled.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a main part of an optical disc recording apparatus according to an embodiment of the present invention.

First, referring to FIG. 1, the main part of the optical disk recording apparatus of the present invention is an optical disk 1 which is a recording medium.
And an optical head 2 for recording / reproducing data on / from the optical disc 1.
A laser diode 3 configured in the optical head 2, a laser driver 4 for driving the laser diode 3, a front monitor 5 for monitoring a light emission output of the laser diode 3 and outputting a monitor signal, and a front monitor 5 APC circuit 6 that performs loop control to keep the laser diode output constant based on the monitor signal
A microprocessor 7, an encoder 8 for modulating recording data, a monitor unit (A / D converter) 9 for monitoring a laser power control set value of the APC circuit 6, and a laser power control separately from the APC circuit 6. Laser power setting section (D /
A converter) 10 and an analog switch 11 for switching APC control when recording is stopped and restarted.

In the optical disk recording apparatus of the present invention, during normal recording, the optimum recording power is constantly controlled by the loop control by the APC circuit 6. The microprocessor 7 makes a judgment such as a buffer underrun to control stop / restart of recording, etc. Further, a switching signal (SS) of the analog switch 11 for switching APC control at the time of recording stop / restart.
W) is also controlled by the microprocessor 7. And
The encoder 8 outputs a switching signal (SLD) for switching ON / OFF of the output of the laser 3, and the actual laser output ON / OF is output by this switching signal (SLD).
F is executed by the laser driver 4.

Next, the data recording process of the present embodiment configured as described above will be described. FIG. 2 is a flowchart showing a part of an example of the data recording process (APC circuit switching timing), and FIG. 3 is a flowchart showing another part of the example of the data recording process.

Referring to FIGS. 2 and 3, first, the CD
-When recording is started by the R drive (step 10
1) The microprocessor 7 monitors the buffer capacity of the buffer that stores the recording data (step 102).
At this time, if the buffer capacity falls below a certain prescribed value, it is judged that the recording is temporarily stopped as a preliminary detection of the buffer underrun (step 103), and the APC circuit 6 immediately before the recording is stopped.
The output laser power control set value (SPW) is fetched from the fetching unit 9 (step 104) and stored.

For A ← Pow capture, the laser power control set value (SPW) of the APC circuit 6 is monitored at a constant interval during recording,
It is also possible to store the final value monitored before recording is stopped.

From the recording pause (step 105) to the recording restart (step 110), the drive enters the recording standby (step 108) operation, during which the microprocessor 7 switches the APC switching signal (SSW) and the analog switch 11 Switching to the laser power setting unit 10 (step 106). Simultaneously with the switching, the laser power setting value fetched before the recording is stopped is set in the laser power setting section 10 (step 107).

(C ← A: Pow) After the above setting, the microprocessor 7 again monitors the buffer capacity, and restarts recording when it is confirmed that the buffer capacity exceeds a certain reference value for starting recording (step 109). When the recording is restarted, the laser diode 3 to step 107
The power equivalent to that before the recording stop set in step 2 is immediately emitted without delay, and recording on the optical disc 1 is restarted.

It is possible to restart recording by setting the laser power setting at the time of restarting recording to be equal to the power before stopping recording.

When the recording is restarted by the laser power control in the APC circuit without switching, the rise of the laser power is delayed by the time constant of the loop filter, and the recording on the optical disc 1 is lost.

The laser power control after the recording is restarted is performed by the laser power setting unit 10. However, since the laser power setting unit 10 cannot keep the optimum laser power as it is, the APC circuit 6
It is necessary to switch to laser power control by.

In this case, the output of the APC circuit 6 at this time is taken in by the monitor unit 9 (step 111) and used as the monitor value (B). The monitor value (B) and the target value (A) are compared (step 112), and it is confirmed that the monitor value (B) and the target value (A) match, and the laser power control is performed by the laser power control. From setting unit 10 to AP
The C circuit 6 is switched to (step 116), and the laser power is controlled to a predetermined optimum value by normal loop control (step 117).

When the monitor value (B) and the target value (A) are different, the set value (C) of the laser power setting section 10 is adjusted. If the monitor value (B) is lower than the target value (A) (step 113, YES), the set value (C) of the laser power setting section is increased (step 11).
4) Control is performed so that the monitor value (B) matches the target value (A). Furthermore, the monitor value (B) is the target value (A)
If it is higher than (step 113, NO), the set value (C) of the laser power setting section is decreased (step 11).
5) Control is performed so that the monitor value (B) matches the target value (A).

That is, by adjusting the setting value (C) of the laser power setting unit 10, the laser power setting unit 10 is set so that the monitor value (B) of the output of the APC circuit 6 and the target value (A) match. By controlling, it becomes possible to suppress the fluctuation of the laser power when the laser power setting unit 10 is switched to the APC circuit 6. However, the target value A here is A taken in immediately before the recording was stopped.
It is the laser power setting value of the PC circuit 6.

By controlling the switching timing from the laser power setting unit 10 to the APC circuit 6 in this way, it is possible to eliminate the disturbance of the output of the APC circuit 6 when switching from the laser power setting unit 10 to the APC circuit 6. This makes it possible to realize power control at the time of restarting recording stop at a stable optimum recording power.

[0036]

As described above, according to the optical disk recording apparatus of the present invention, the writing quality to the optical disk at the time of recording stop and recording restart at the time of buffer underrun countermeasures can be kept stable even at high speed recording. In addition, it is possible to read the recorded optical disc with another reading device without causing a reading error. That is, it is possible to provide a laser power control that realizes an essential function for increasing the speed of an optical disc recording device.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of an optical disc recording apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a part of an example of a data recording process.

FIG. 3 is a flowchart showing another part of the example of the data recording process of FIG.

[Explanation of symbols]

1 optical disc 2 optical head 3 laser diode 4 laser driver 5 Front monitor 6 APC circuit 7 microprocessors 8 encoder 9 Monitor section (A / D converter) 10 Laser power setting section (D / A converter) 11 analog switch

Continued front page    F term (reference) 5D090 AA01 BB03 BB04 CC09 CC18                       DD03 EE01 KK03                 5D119 AA23 AA24 BA01 BB02 BB04                       DA01 HA13 HA28 HA46                 5D789 AA23 AA24 BA01 BB02 BB04                       DA01 HA13 HA28 HA46

Claims (6)

[Claims] 1. An optical head for recording / reading data by irradiating an optical disk with laser light, an automatic output control circuit for controlling the output of the laser light emitted by the optical head to a constant value, and the automatic output control circuit. Separately, a setting unit for setting the output of the laser light, a monitor unit for monitoring the output value of the automatic output control circuit and the setting unit, a switching circuit for switching between the automatic output control circuit and the setting unit, An optical disc recording apparatus, comprising: a control unit for instructing the setting unit based on a result obtained from the monitor unit. 2. The optical disk recording apparatus according to claim 1, having a recording stop and restart function. 3. The optical disc recording apparatus according to claim 1, wherein the optical disc is a write-once type optical disc in which a dye is used for a recording film. 4. The optical disc recording apparatus according to claim 1, wherein the optical disc is a write-once type optical disc using a phase change film as a recording film. 5. A laser power control method for an optical disk recording apparatus according to claim 2, wherein the control means monitors a set value of an automatic output control circuit during recording to immediately before recording interruption. Memorize the setting value of
The laser power control method, wherein the setting unit sets a set value immediately before the recording is interrupted and outputs a laser beam when the recording is restarted. 6. After the recording is resumed, the output value of the automatic output control circuit is monitored by the monitor section, and the control means compares the set value with the output of the automatic output control circuit to adjust the set value to set the set value. 7. The laser power control method according to claim 6, wherein the switching timing from the control of the laser light output in the unit to the control of the laser light output by the automatic output control circuit is controlled.