JPH05120686A - Method and device for controlling laser driving of optical magnetic head - Google Patents

Abstract

PURPOSE:To rapidly output the required object recording deletion power from a semiconductor laser by superimposing the reproduction error signal just before the reproduction on a recording reference signal, thereby correcting the recording reference signal. CONSTITUTION:At a recording mode, a power detection signal Vmw following the power of a semiconductor laser 54 is outputted from a recording signal detection circuit, and a reproduction detection signal Vmr at the reproduction is held during the recording mode. Then, the feedback control is performed by using both signals while taking an APC control signal as 'H'. The peak hold is released with the stable output of the laser 54. At the reproduction mode, the reproduction power of the laser 54 is outputted by the feedback control using a reproduction reference signal Vrr and a detection signal Vmr, and a recording detection signal Vmw and a deletion detection signal Vme are supplied. The laser output is increased according to the reference signal Vrw. The feedback control is finished while taking the APC signal as 'L'. Further, a reproduction error signal is calculated by operation amplifiers 78 and 80, and the temperature correction of a reproduction error signal A78 (Vrr-Vmr) is performed by overlapping the recording reference signal Vrw or a deletion reference signal Vre through an operation amplifier 96.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser drive control method and apparatus for a magneto-optical head for driving and controlling a semiconductor laser in a magneto-optical head of a magneto-optical disk device.

[0002]

2. Description of the Related Art A magneto-optical disk device is a storage device having a large storage capacity like a conventional write-once optical disk device, and also enables recording and erasing of information, which cannot be done by the write-once optical disk device. In recent years, products relating to magneto-optical discs have appeared, and magneto-optical disc technology is approaching the stage of commercialization from the stage of trial production.

In the magneto-optical disk device, data reproduction is performed by detecting the rotation angle of the plane of polarization of the reflected light of the laser beam applied to the magneto-optical disk, and data recording / erasing is performed on the magneto-optical disk. It is carried out by irradiating a laser beam to locally heat it to the Curie point or higher and inverting the magnetic field by an external magnetic field. Even if the magneto-optical disk is irradiated with the laser beam as described above, the required laser beam power is different between the data reproduction and the data recording / erasing. That is, the power of the laser beam at the time of data reproduction needs to be higher than the rotation angle of the polarization plane can be detected, but the magneto-optical disk should not be heated to above the Curie point. The power of the laser beam at the time of recording / erasing data must be sufficient to heat the magneto-optical disk to the Curie point or higher.

As described above, it is necessary to drive and control the semiconductor laser in the magneto-optical head so as to output different powers during data reproduction and during data recording / erasing. Therefore, a reproduction reference signal that serves as a reference for a current value that outputs a desired power when reproducing data, a recording reference signal that serves as a reference for a current value that outputs a desired power during data recording, and The erasing reference signal serving as a reference of the current value for outputting the power of is determined, and the drive is controlled so that the detection signal corresponding to the power detected from the semiconductor laser becomes these reference signals.

[0005]

Generally, a semiconductor laser has a characteristic that the output power with respect to the same drive current decreases as the temperature rises. Therefore, it is necessary to drive the semiconductor laser by correcting the temperature of the reference signal according to the temperature of the semiconductor laser. However, in the conventional magneto-optical head, feedback drive control is performed independently during data reproduction, data recording, and data erasing. Therefore, when the mode is switched, a constant feedback control time is required to reach the desired power. Was needed.
In particular, when recording or erasing data, it is necessary to record or erase the data immediately after switching, but the power required for recording or erasing the data is delayed and the data can be accurately recorded. There is a problem in that it may not be possible or data may not be erased reliably.

It is an object of the present invention to provide a laser drive control method and apparatus for a magneto-optical head capable of rapidly switching from a data reproduction mode to a data recording mode.

[0007]

The above object is to provide a reproduction reference signal which is predetermined for outputting a desired reproduction power from the semiconductor laser when reproducing data, and which has a reproduction error based on the power detected from the semiconductor laser. A recording error signal based on the power detected from the semiconductor laser is added to a recording reference signal that is predetermined to output a desired recording power from the semiconductor laser when data is recorded by driving the semiconductor laser by superimposing a signal. In the laser drive control method of a magneto-optical head for driving the semiconductor laser by superimposing the recording reference signal on the recording reference signal by superimposing the reproduction error signal at the time of immediately preceding data reproduction on the recording reference signal. This is achieved by a laser drive control method for a magneto-optical head, which is characterized in that correction is performed.

[0008] Further, the above-mentioned object is to detect the power output from the semiconductor laser, and to use a predetermined reproduction reference signal for outputting a desired reproduction power from the semiconductor laser at the time of data reproduction. Reproduction driving means for driving the semiconductor laser by superimposing a reproduction error signal based on the power detected by the power detection means, and a predetermined recording for outputting a desired recording power from the semiconductor laser at the time of data recording. The reproduction error signal at the time of immediately preceding data reproduction is superimposed on the reference signal to correct the recording reference signal, and to the corrected recording reference signal,
And a recording drive unit that drives the semiconductor laser by superimposing a recording error signal based on the power detected by the power detection unit.

[0009]

According to the present invention, at the time of data recording, the recording reference signal is corrected by superimposing the reproduction error signal at the time of immediately preceding data reproduction on the recording reference signal. The semiconductor laser can be driven so as to quickly output a desired target recording / erasing power when the value changes to.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser drive controller for a magneto-optical head according to an embodiment of the present invention will be described with reference to FIGS. Figure 1
2 is a circuit diagram of the laser drive controller for the magneto-optical head of this embodiment. First, a circuit for detecting the power of the semiconductor laser in the magneto-optical head shown in FIG. 1 will be described.

The photodetector 10 detects the power of the semiconductor laser in the magneto-optical head. The detection current signal of the photodetector 10 is converted into a voltage detection signal by the operational amplifier 12. The anode of the photodetector 10 is grounded, and the cathode is connected to the inverting input terminal of the operational amplifier 12. A resistor 14 is inserted between the non-inverting input terminal and the output terminal of the operational amplifier 12.

The voltage signal converted by the operational amplifier 12 is amplified by the inverting buffer amplifier 16 to detect the power of the semiconductor laser at the time of recording data, and the power of the semiconductor laser at the time of erasing data is detected. It is output to the erase signal detection circuit 20 and the reproduction signal detection circuit 22 that detects the power of the semiconductor laser during data reproduction. The gate timing control circuit 24 generates a control signal for timing controlling the recording signal detection circuit 18, the erase signal detection circuit 20, and the reproduction signal detection circuit 22 from the recording gate signal output in synchronization with the track sector.

The recording signal detection circuit 18 is composed of a first peak hold circuit 26 and a second peak hold circuit 28 having different time constants. A first peak hold circuit 26 having a short time constant is connected to the inverting buffer amplifier 16. In this embodiment, the rise time of the first peak hold circuit 26 is 0.5 μsec and the fall time is several μsec.

A variable resistor 30 is connected to the output terminal of the first peak hold circuit 26, and a second peak hold circuit 28 having a long time constant is connected to the variable resistor 30.
The second peak hold circuit 28 is reset by the peak reset signal. In this embodiment, the rise time of the second peak hold circuit 30 is 20 μsec and the fall time is 10 minutes.

The output terminal of the first peak hold circuit 26 and the output terminal of the second peak hold circuit 28 are connected to a changeover switch 32. The changeover switch 32 is changed over by a peak hold control signal from the gate timing control circuit 24. The signal switched by the changeover switch 32 becomes the recording detection signal Vmw. The erase signal detection circuit 20 is composed of a third peak hold circuit 34 having a long time constant. The variable resistor 36 is directly connected to the output terminal of the inverting buffer amplifier 16, and the variable resistor 36
A third peak hold circuit 34 having a long time constant is connected to. Since the variable resistor 36 is directly connected to the output terminal of the inverting buffer amplifier 16, it is substantially the same as the peak hold circuit having a very short time constant (zero time constant). Third peak hold circuit 34
Are reset by the peak reset signal. In the present embodiment, the rise time of the third peak hold circuit 34 is 20 μsec and the fall time is 10 minutes.

The signal line directly connected to the output terminal of the inverting buffer amplifier 16 and the output terminal of the third peak hold circuit 34 are connected to the changeover switch 38. The changeover switch 38 is changed over by a peak hold control signal from the gate timing control circuit 24. The signal switched by the changeover switch 38 becomes the erase detection signal Vme.

The reproduced signal detection circuit 22 is composed of a sample hold circuit 40. The sample and hold circuit 40 is responsive to the sample and hold control signal from the gate timing control circuit 24 to invert the buffer amplifier 16
The voltage detection signal from is sampled or held.
A variable resistor 42 is provided at the output terminal of the sample hold circuit 40.
Is connected, and the signal from the variable resistor 42 is the reproduction detection signal V
It becomes mr.

Next, a circuit for driving and controlling the semiconductor laser based on the power detection signal will be described with reference to FIG. Using the detection signal detected by the circuit of FIG. 1, the semiconductor laser is feedback-controlled so that it becomes a predetermined reference signal. A recording detection signal Vmw, an erasure detection signal Vme, and a reproduction detection signal Vmr are input as detection signals from the circuit of FIG. 1, and a reference signal indicating a reference value of a current for outputting a desired power from the semiconductor laser during data recording is recorded. A reference signal Vrw, an erase reference signal Vre indicating a reference value of a current for outputting a desired power from the semiconductor laser at the time of data erasing, and a reproduction reference signal Vrr indicating a reference value of a current for outputting a desired power from the semiconductor laser at the time of data reproduction are included. It has been entered. The drive current for outputting the desired power from the semiconductor laser varies depending on the temperature, but in the present embodiment, it is stable after the semiconductor laser is driven for a certain period of time as the recording reference signal Vrw, the erase reference signal Vre, and the reproduction reference signal Vrr. The required current value is selected at the specified temperature.

First, a circuit for driving and controlling the semiconductor laser by feedback control during data reproduction will be described. A signal obtained by correcting the reproduction reference signal Vrr with the reproduction detection signal Vmr is generated by the operational amplifier 44. The reproduction detection signal Vmr is input to the inverting input terminal of the operational amplifier 44 via the resistor 46, and the reproduction reference signal Vrr is input to the non-inverting input terminal thereof via the resistor 48. The terminal of the resistor 48 opposite to the operational amplifier 44 is grounded to the resistor 50.
Are connected. A resistor 52 is inserted between the output terminal and the inverting input terminal of the operational amplifier 44. From the output terminal of the operational amplifier 44, a reproduction control signal (Vrr-) in which an error signal (Vrr-Vmr) of the reproduction detection signal Vmr with respect to the reproduction reference signal Vrr is superimposed on the reproduction reference signal Vrr.
A ₄₄ (Vrr-Vmr): A ₄₄ is the amplification factor of the operational amplifier 44.

An operational amplifier 56 is provided on the output side of the operational amplifier 44 in order to drive the semiconductor laser 54 with a constant drive current according to the superimposed reproduction control signal (Vrr-A ₄₄ (Vrr-Vmr)). A transistor 58 is provided. The non-inverting input terminal of the operational amplifier 56 is connected to the output terminal of the operational amplifier 44, the inverting input terminal is connected to the emitter of the transistor 58, and the output terminal is connected to the base of the transistor 58. The emitter of the transistor 58 is grounded via the resistor 60, and the collector is connected to the cathode of the semiconductor laser 54. Since the transistor 58 is driven so that the potentials of the non-inverting input terminal and the inverting input terminal of the operational amplifier 56 become the same, the semiconductor laser 54 receives the reproduction control signal (Vrr-A ₄₄ (Vrr-V).
A constant current corresponding to mr)) is applied.

In this way, even if the temperature of the semiconductor laser 54 changes, the desired reproduction power is output by the feedback control. Next, a circuit for controlling the driving of the semiconductor laser by feedback control during data recording or data erasing will be described. The same circuit is used to drive and control the semiconductor laser during data recording and data erasing. Therefore, the changeover switch 60 switches between the recording detection signal Vmw and the erase detection signal Vme, and the changeover switch 62 changes the recording reference signal Vrw and the erase reference signal Vme.
re is switched. The changeover switch 60 and the changeover switch 62 are changed over by a recording / erasing changeover signal.

On the output side of the changeover switch 60, a changeover switch 64 is provided for changing over between closed loop feedback control (APC) and open loop control (OL). One of the input terminals of the changeover switch 64 is connected to the output terminal of the changeover switch 60, and the other is connected to the output terminal of the changeover switch 62.

The operational amplifier 66 has a detection signal Vmw / Vm.
It is provided to detect an error between e and the reference signal Vrw / Vre. The inverting input terminal of the operational amplifier 66 is connected to the output terminal of the changeover switch 60 via the resistor 68,
The non-inverting input terminal has a changeover switch 62 via a resistor 70.
Is connected to the output terminal of. The non-inverting input terminal of the operational amplifier 66 is further connected to the grounded resistor 72, and the resistor 74 is inserted between the inverting input terminal and the output terminal. The recording error signal (A ₆₆ (Vrw
-Vmw): A ₆₆ is the amplification factor of the operational amplifier 66) or the erasure error code (A ₆₆ (Vre-Vme)) is output.

The operational amplifier 75 has a reference signal Vrw / Vr.
e buffer. The non-inverting input terminal of the operational amplifier 75 is a variable resistor 7 connected to the input terminal of the changeover switch 64.
Connected to 6. The inverting input terminal and the output terminal of the operational amplifier 75 are directly connected. The operational amplifier 78 and the operational amplifier 80 generate a reproduction reference signal Vrr and a reproduction detection signal Vm.
It is provided to calculate and amplify a reproduction error signal (Vrr-Vmr) with r. The reproduction detection signal Vmr is input to the inverting input terminal of the operational amplifier 78 via the resistor 82, and the reproduction reference signal Vrr is input to the non-inverting input terminal thereof via the resistor 84. The non-inverting input terminal of the operational amplifier 78 is further connected to the grounded resistor 86, and the resistor 88 is inserted between the inverting input terminal and the output terminal.
A variable resistor 90 is connected to the output terminal of the operational amplifier 78, and the variable resistor 90 is provided with a low-pass filter including a resistor 92 and a capacitor 94. Operational amplifier 8
The inverting input terminal of 0 and the output terminal are directly connected. The operational amplifier 80 is a buffer for an error signal whose high frequency is cut by a low pass filter. Operational amplifier 8
From 0, the reproduction error signal (A ₇₈ (Vrr-Vmr): A ₇₈
Is output as the amplification factor of the calculation 78.

The operational amplifier 96 includes three operational amplifiers 6.
The output signals from 6, 75 and 78 are added and amplified. The inverting input terminal of the operational amplifier 96 is connected to the output terminal of the operational amplifier 66 via the resistor 98, the output terminal of the operational amplifier 75 to the resistor 100, and the output of the operational amplifier 80 via the resistor 102. The terminals are connected. The non-inverting input terminal of the operational amplifier 98 is grounded via the resistor 104, and the resistor 106 is inserted between the inverting input terminal and the output terminal.

The recording error signal output from the operational amplifier _{66 (A 66 (Vrw-Vmw} )) erase error Institute No. (A ₆₆ (V
re-Vme)), the recording reference signal Vrw or the erase reference signal output from the operational amplifier 75, and the operational amplifier 80.
The reproduction error signal (A ₇₈ (Vrr-Vm
r)) is superposed by the operational amplifier 96. That is, at the time of data recording or data erasing, the recording reference signal Vrw or the erasing reference signal Vre is temperature-corrected using the reproduction error signal (A ₇₈ (Vrr-Vmr)) at the time of data reproduction, and the temperature-corrected recording reference signal ( Vrw + A ₇₈ (Vrr
-Vmr)) or erase reference signal (Vre + A ₇₈ (Vrr
-Vmr)) to the recording error signal (A ₆₆ (Vrw-Vm
w)) or an erasing error signal (A ₆₆ (Vre-Vme)) is superimposed on the recording control signal (Vrw + A ₇₈ (Vrr-Vm).
r) + A ₆₆ (Vrw-Vmw)) or erase control signal (V
re + A ₇₈ (Vrr-Vmr) + A ₆₆ (Vre-Vm
Controlled by e)), the semiconductor laser 54 outputs the desired recording power or erasing power.

An operational amplifier 108 is provided to invert the output signal of the operational amplifier 96. Operational amplifier 96
Is connected to the inverting input terminal of the operational amplifier 108 via the resistor 110. The non-inverting input terminal of the operational amplifier 108 is grounded via the resistor 112, and the resistor 114 is inserted between the inverting input terminal and the output terminal. On the output side of the operational amplifier 108, a recording control signal (Vrw +
A ₇₈ (Vrr-Vmr) + A ₆₆ (Vrw-Vmw)) or erase control signal (Vre + A ₇₈ (Vrr-Vmr) + A
_In order to drive the semiconductor laser 54 with a constant drive current according to ₆₆ (Vre-Vme)), the operational amplifier 116
And a transistor 118 are provided. Operational amplifier 1
The non-inverting input terminal of 16 is connected to the output terminal of the operational amplifier 108, the inverting input terminal is connected to the emitter of the transistor 118, and the output terminal is connected to the base of the transistor 118. The emitter of the transistor 118 is grounded via the resistor 120. Operational amplifier 116
Since the transistor 118 is driven so that the electric potentials of the non-inverting input terminal and the inverting input terminal of the transistor 118 are the same, the semiconductor laser 54 has the recording control signal (Vrw + A ₇₈ (Vrr-Vm
r) + A ₆₆ (Vrw-Vmw)) or erase control signal (V
re + A ₇₈ (Vrr-Vmr) + A ₆₆ (Vre-Vm
A constant current flows according to e)).

The collector of the transistor 118 is connected to the cathode of the semiconductor laser 54 via the modulation circuit 122. Since the modulation circuit 122 is modulated so as to turn on / off based on the input recording data, the semiconductor laser outputs a desired recording power to turn on / off according to the recording data. Next, the operation of the laser drive controller for the magneto-optical head according to this embodiment will be described with reference to FIGS.

First, the operation of the circuit for detecting the power of the semiconductor laser in the magneto-optical head shown in FIG. 1 will be described with reference to FIG.
The time chart will be described. The operation when recording data in two consecutive sectors will be described as an example. At the bottom of FIG. 3, various control signals for recording data are shown. First, these various control signals will be described.

The recording mode signal is a signal indicating the data recording mode, and a magnetic field for recording is applied to the magneto-optical disk while the recording mode signal is at a high level. The recording mode signal is at a high level during the period over two consecutive sectors. The recording gate signal is a signal indicating a period during which data is actually recorded.It is at a high level only during the period of the data portion where data is actually recorded in each sector, and the data is read during the period of the pre-pitted pre-format portion, so it is at the low level Becomes

The peak hold control signal is a signal obtained by delaying the high level of the data portion of the recording gate signal by a certain period at the time of rising, and the changeover switch 32 of the recording signal detection circuit 18 and the erase signal detection circuit 20. The changeover switch 38 is controlled. When the peak hold control signal is at the high level, the peak hold circuit 26 with the shorter time constant is used.
The output signal of the peak hold circuit 28 or 34 having a longer time constant is switched to the output signal of the peak hold circuit 28 or 34 when the output signal is at the low level.

The APC control signal is APC (Auto Po
wer control) is a signal for controlling whether to perform control. The APC control signal becomes high level after a certain time has elapsed since the recording mode signal became high level. Even if the recording mode signal becomes high level, it is an open loop for a certain period of time, and after a certain period of time, it becomes a closed loop to perform APC control.

The peak reset signal is a signal for resetting the second peak hold circuit 28 of the recording signal detection circuit 18 and the third peak hold circuit 34 of the erase signal detection circuit 20. The sample hold signal is a signal for controlling the sample hold circuit 40 of the reproduction signal detection circuit 22, holds data at a high level, and samples data at a low level. The data section has a high level during the period, and the preformat section has a low level during the period.

The circuit shown in FIG. 1 is controlled according to the above-mentioned control signals to detect the power of the semiconductor laser. Initially, the recording mode signal is in the low level and the data reproduction mode, and as shown in the optical power monitor signal of FIG. 3, feedback control using the reproduction reference signal Vrr and the reproduction detection signal Vmr enables the semiconductor laser 54 to obtain a desired signal. The playback power of is being output. At this time, the sample hold control signal is at a low level, and the sample hold circuit 40 of the reproduction signal detection circuit 22 is sampling the power of the semiconductor laser 54.

When the recording mode signal becomes high level, the peak reset signal is made high level for a short time to reset the second peak hold circuit 28 of the recording signal detection circuit 18 and the third peak hold circuit 30 of the erase signal detection circuit 20. To do. This is to remove the influence of external noise before entering the data recording mode. Subsequently, when the recording gate signal becomes high level and the recording mode is set, a large current corresponding to the recording reference signal Vrw is supplied to the semiconductor laser 54, and the output power of the semiconductor laser 54 becomes as large as possible to obtain a desired recording power. At this point, since the output of the semiconductor laser 54 is not stable just after entering the recording mode, the APC control signal is kept at the low level and the open loop control (OL) is performed by the changeover switch 64. The recording reference signal Vr is applied to the semiconductor laser 54.
The current value according to w is supplied without feedback control.

Regarding the recording reference signal Vrw or the erasing reference signal Vre when the data reproducing mode is changed to the data recording mode or the data erasing mode, a reproducing error signal (A ₇₈ (Vrr-Vmr)) at the time of reproducing the data is used.
The recording reference signal Vrw or the erasing reference signal Vre is corrected by the method, the details of which will be described later. When the recording gate signal becomes high level and the recording mode is set, the first peak hold circuit 26 and the second peak hold circuit 26 of the recording signal detection circuit 18
The third of the peak hold circuit 28 and the erase signal detection circuit 20
The peak of the recording signal level is detected by the peak hold circuit 34. As shown in FIG. 3, the first peak hold circuit 26 of the recording signal detection circuit 18 has a short time constant, so that its output signal rises rapidly. However, since the second peak hold circuit 28 has a long time constant, its output signal gradually rises. When the peak hold control signal changes to high level, the changeover switch 32 switches to the first peak hold circuit 26 having a short time constant, and the recording signal detection circuit 18 outputs the power detection signal Vmw that substantially follows the power of the semiconductor laser 54. Is output.

On the other hand, at the same time as the change of the recording gate signal, the sample-hold control signal is set to the high level, the reproduction power of the semiconductor laser 54 sampled by the sample-hold circuit 40 of the reproduction signal detection circuit 22 is held, and the reproduction of FIG. As indicated by the detection signal Vmr, the reproduction detection signal Vmr during data reproduction is maintained even during the data recording mode.

Subsequently, the APC control signal is set to a high level, and feedback control using the recording detection signal Vmw from the recording signal detection circuit 18 and the recording reference signal Vrw is performed. Then, when the output of the semiconductor laser 54 stabilizes, the peak reset signal resets the second peak hold circuit 28 and the third peak hold circuit 34. When the output of the semiconductor laser 54 is unstable, there is a possibility that the peak of the detection signal that is too large may be held. Therefore, in order to remove the effect and hold the peak of the detection signal when the semiconductor laser 54 is in a stable state. Is.

When the period of the data section has passed and the preformat section is entered, the recording gate signal goes low and the data reproduction mode is set. As shown by the optical power monitor signal in FIG. 3, the feedback control using the reproduction reference signal Vrr and the reproduction detection signal Vmr reduces the power of the semiconductor laser 54 and outputs the reproduction power. Therefore, FIG.
As shown in, the first peak hold circuit 2 having a short time constant
Although the output signal of 6 decreases, the output signal of the second peak hold circuit 28 having a long time constant is kept high.

Therefore, the peak hold control signal is set to the low level in synchronization with the recording gate signal, and the changeover switch 3
2 and 38 are switched to change the output signal of the second peak hold circuit 28 from the recording signal detection circuit 18 to the recording detection signal Vmw.
And the output signal of the third peak hold circuit 34 is output from the erase signal detection circuit 20 as the erase detection signal Vme.

On the other hand, the sample hold control signal is set to the low level after a certain time delay from the change of the recording gate signal,
The reproduction power of the semiconductor laser 54 is sampled by the sample hold circuit 40 of the reproduction signal detection circuit 22.
When the recording gate signal becomes high level and becomes the recording mode when the period of the pre-formatted portion has passed and the data portion has come again, a large current corresponding to the recording reference signal Vrw is supplied to the semiconductor laser 54, and the desired recording power is obtained again. The output power of the semiconductor laser 54 becomes as large as possible.

When the recording gate signal becomes high level to enter the recording mode, the first peak hold circuit 26 and the second peak hold circuit 28 of the recording signal detection circuit 18 and the third peak hold circuit 34 of the erase signal detection circuit 20. Although the peak of the recording signal level is detected, as shown in FIG. 3, since the first peak hold circuit 26 of the recording signal detection circuit 18 has a short time constant, its output signal rapidly rises, but the second peak. Since the hold circuit 28 has a long time constant, its output signal gradually rises. When the peak hole control signal changes to the high level, the changeover switch 32 switches to the first peak hold circuit 26 having a short time constant, and the recording signal detection circuit 18 outputs the power detection signal Vmw that substantially follows the power of the semiconductor laser 54. Is output.

On the other hand, at the same time as the change of the recording gate signal, the sample-hold control signal is set to the high level, the reproduction power of the semiconductor laser 54 sampled by the sample-hold circuit 40 of the reproduction signal detection circuit 22 is held, and the reproduction of FIG. As indicated by the detection signal Vmr, the reproduction detection signal Vmr during data reproduction is maintained even during the data recording mode.

Subsequently, when the period of the data portion of the second sector has passed, the recording gate signal becomes low level and the data reproduction mode is set. The peak hold control signal is set to the low level in synchronization with the recording gate signal, and the changeover switches 32, 38
The output signal of the second peak hold circuit 28 is output from the recording signal detection circuit 18 as the recording detection signal Vmw, and the output signal of the third peak hold circuit 34 is output from the erase signal detection circuit 20. Is output as.

The sample and hold control signal becomes low level after a certain period of delay from the change of the recording gate signal, and the reproducing power of the semiconductor laser 54 is sampled by the sample and hold circuit 40 of the reproducing signal detecting circuit 22. Further, the APC control signal is set to low level to end the feedback control at the time of data recording.

Then, the peak reset signal is set to a high level to reset the levels of the second peak hold circuit 28 of the recording signal detection circuit 18 and the third peak hold circuit 30 of the erase signal detection circuit 20. As a result, as shown in FIG. 3, the recording detection signal Vm of the recording signal detection circuit 18 is generated.
w is reset, and a series of data recording operation is completed.

Next, the temperature correction control of the recording reference signal Vrw or the erasing reference signal Vre when the data reproducing mode is changed to the data recording mode or the data erasing mode will be described with reference to FIG. The drive current I _LD of the semiconductor laser 54 and the output power P have a substantially linear relationship.
It is known that the output power P varies depending on the temperature T even with the same drive current I _LD . As the temperature T increases, the power output from the semiconductor laser 54 decreases for the same drive current I _LD . That is, the case where the temperature T of the semiconductor laser 54 is Ti in the initial state and the case where the temperature T of the semiconductor laser 54 is Tf in the stable state are shown in FIG.
As shown in, the relationship between the drive current I _LD and the output power P is different.

In this embodiment, as an example, the reproduction reference signal Vrr and the reproduction reference signal Vrr are output so that the desired target reproduction power and the desired target recording / erasing power are output when the temperature T at which the semiconductor laser 54 is in a stable state is Tf. The recording reference signal Vrw and the erasing reference signal Vre are defined. Therefore, for example, if the temperature T of the semiconductor laser 54 is Ti in the initial state, the current value based on the reproduction reference signal Vrr greatly exceeds the target reproduction power. Therefore, FIG. 1 and FIG.
Feedback control is performed by the circuit shown in FIG. 3 to correct the current value based on the reproduction reference signal Vrr so that only the current value ΔI _LD becomes small as shown in FIG. There is. A reproduction control signal (Vrr-A ₄₄ (Vrr-Vmr)) in which an error signal (Vrr-Vmr) of the reproduction detection signal Vmr with respect to the reproduction reference signal Vrr is superimposed on the reproduction reference signal Vrr from the operational amplifier 44.
Is output.

When the data reproducing mode is changed to the data recording mode or the data erasing mode, the temperature T of the semiconductor laser 54 is Ti, and therefore the recording reference signal Vr.
If a current value based on w or the erase reference signal Vre is passed, the target recording / erasing power will be greatly exceeded. Finally, feedback control is performed so that the target recording / erasing power is output using the recording detection signal Vmw or the erasing detection signal Vme, but it takes time to reach the desired target recording / erasing power.

Therefore, in the present embodiment, attention is paid to the fact that the current value ΔI _{LD for} temperature correction is almost the same in both the data reproducing mode, the data recording mode and the data erasing mode, and the recording reference signal Vrw or the erasing reference signal Vre. The temperature is corrected in advance by the current value ΔI _{LD corresponding to the} temperature correction in the immediately preceding data reproduction mode so that the desired target recording / erasing power can be reached quickly.

That is, the operational amplifier 78 and the operational amplifier 8
The reproduction error signal (Vrr-Vmr) between the reproduction reference signal Vrr and the reproduction detection signal Vmr is calculated and amplified by 0, and the reproduction reference signal Vrr and the reproduction detection signal are converted into the recording reference signal Vrw or the erase reference signal Vre by the operational amplifier 96. Vmr
And the reproduction error signal (A ₇₈ (Vrr-Vmr)) are superimposed to correct the temperature.

As described above, according to this embodiment, when the data recording mode or the data erasing mode is changed from the time of reproducing the data, the semiconductor laser can promptly output the desired target recording / erasing power. .. The present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above embodiment, the erase detection signal is detected independently of the recording detection signal, and the erase reference signal is defined independently of the recording reference signal.
The recording detection signal may be used also as the erasing detection signal, and the recording reference signal may be used also as the erasing reference signal.

Further, the circuits in the above embodiments are only specific examples, and may have any circuit configuration as long as they realize the drive control method of the present invention.

[0054]

As described above, according to the present invention, at the time of data recording, the recording reference signal is corrected by superposing the reproduction error signal at the time of immediately preceding data reproduction on the recording reference signal. When the reproduction mode is changed to the data recording mode, the semiconductor laser can quickly output the desired target recording / erasing power.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a laser drive controller for a magneto-optical head according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a laser drive controller for a magneto-optical head according to an embodiment of the present invention.

FIG. 3 is a time chart showing the operation of the laser drive control device for the magneto-optical head according to the present embodiment.

FIG. 4 is a graph showing a relationship between a drive current and an output power of a semiconductor laser used in a magneto-optical head.

[Description of Codes] 10 ... Photodetector 12 ... Operational amplifier 14 ... Resistor 16 ... Buffer amplifier 18 ... Recording signal detection circuit 20 ... Erase signal detection circuit 22 ... Reproduction signal detection circuit 24 ... Gate timing control circuit 26 ... First peak hold circuit 28 ... 2nd peak hold circuit 30 ... Variable resistance 32 ... Changeover switch 34 ... 3rd peak hold circuit 36 ... Variable resistance 38 ... Changeover switch 40 ... Sample hold circuit 42 ... Variable resistance 44 ... Operational amplifier 46, 48, 50, 52 ... resistance 54 ... semiconductor laser 56 ... operational amplifier 58 ... transistor 60 ... resistance 62, 64 ... changeover switch 66 ... operational amplifier 68, 70, 72, 74 ... resistance 75 ... operational amplifier 76 ... variable resistance 78, 80 ... operational amplifier 82 , 84, 86, 88 ... Resistance 90 ... Variable resistance 92 ... Resistance 4 ... condenser 96 ... operational amplifier 98,100,102,104,106 ... resistor 108 ... operational amplifier 110, 112, 114 ... resistor 116 ... operational amplifier 118 ... transistor 120 ... resistor 122 ... modulation circuit

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[Procedure amendment]

[Submission date] December 18, 1991

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

Claims (2)

[Claims] 1. A semiconductor laser in which a reproduction error signal based on the power detected from the semiconductor laser is superimposed on a reproduction reference signal which is predetermined for outputting a desired reproduction power from the semiconductor laser during data reproduction. Drive
At the time of data recording, a magneto-optical device for driving the semiconductor laser by superimposing a recording error signal based on the power detected from the semiconductor laser on a recording reference signal predetermined for outputting a desired recording power from the semiconductor laser. In the head laser drive control method, at the time of data recording, the recording reference signal is corrected by superimposing the reproduction error signal at the time of immediately preceding data reproduction on the recording reference signal. Drive control method. 2. A power detection means for detecting the power output from the semiconductor laser, and a reproduction reference signal predetermined for outputting a desired reproduction power from the semiconductor laser at the time of data reproduction, by the power detection means. A reproduction drive means for driving the semiconductor laser by superimposing a reproduction error signal based on the detected power, and a recording reference signal which is predetermined for outputting a desired recording power from the semiconductor laser at the time of data recording. The reproduction error signal at the time of reproducing the data is corrected to correct the recording reference signal, and the recording error signal based on the power detected by the power detecting means is superposed on the corrected recording reference signal. A laser drive control device for a magneto-optical head, comprising: a recording drive unit that drives a laser.