JPH0963093A - Laser light output control circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light output control circuit making coincide recording setting power of a laser diode in an ALPC part of an ISO standard sector/ format with real recording peak power. SOLUTION: A DC lighting light output of the laser diode LD 1 is detected by a photodiode PD 2, and an output voltage of a current/voltage conversion circuit 5 is compared with a peak value APC voltage 21a of a recording; power setting voltage by a recording error amplifier 12, and the output voltage of the recording error amplifier 12 is held by a hold circuit 14 in an ALPC part period of an optical disk. When the real peak power is insufficient for the peak power of the LD 1 based on the hold voltage, a correction voltage answering to a shortage is added by a hold voltage correction addition/ subtraction circuit 14 at a real recording time, and the hold voltage is corrected. Further, the hold voltage is corrected by light emitting the DD 1 with a recording time shortest repeat pulse in the ALPC part at a mean value APC also.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser light output control circuit, and more particularly to a laser light output control circuit suitable for controlling the light output of a semiconductor laser incorporated in an optical pickup device used for recording / reproducing of a magneto-optical disk. Regarding

[0002]

2. Description of the Related Art A magneto-optical disk is known as a rewritable optical disk, and an optical pickup device incorporating a semiconductor laser is used for this rewriting and reproduction. To record (write) data on the magneto-optical disk, the magneto-optical disk is first magnetized downward, for example, to bring it into an erased state. The temperature of the portion for recording information is instantly raised to about 120 ° C. by the laser light. At this time, if a weak magnetic field of about several hundred Oersted is applied upward, the magnetization is inverted upward only in the portion where the temperature rises in the cooling process, and is recorded as binary information.

On the other hand, reproduction (reading) is carried out by decomposing the reflected light of the laser light applied to the recording pits of the magneto-optical disk with a polarization beam splitter and guiding it to an optical pickup device for detecting the polarization direction. . Further, in order to erase the recorded data, when the direction of the magnetic field applied to the recording pit from the outside is downward and the laser light is continuously irradiated, the magnetization of the disk is entirely downward and the disk is in an erased state.

Information is read out without destroying recording pits by irradiating a laser beam weaker than that at the time of recording, because the output of the laser beam irradiated at the time of recording, reproducing and erasing on the magneto-optical disk is different. It is designed to be done.

Therefore, it is necessary to sufficiently control the laser light output of the laser beam applied to such an optical disk in the recording, reproducing, and erasing modes. Normally, the light output of the semiconductor laser is At the same time as switching for each mode, an APC circuit (Automatic Power Coupling) which is a semiconductor laser drive circuit is configured to input three kinds of set voltages for obtaining an optimum optical output in each mode.
ntrol circuit).

FIG. 12 shows an example of the APC circuit for controlling the laser light output. In FIG. 12, AP
The C circuit includes a semiconductor laser diode 1 (hereinafter referred to as LD1) and a photodiode 2 for monitoring the optical output of LD1.
(Hereinafter referred to as PD2), interlocking mode changeover switches 3a and 3b (reproducing R, recording W, erasing E), high-frequency oscillation circuit 4, current-voltage conversion circuit 5, error amplifier 6, and light output in each mode is determined. Set voltage 7, current booster 9,
The adding circuit 10 is provided. Then, the adder circuit 10
Then, the outputs of the recording signal generating circuit 8 and the error amplifier 6 are added and applied to the current booster 9.

The PD2 may be provided separately from the one in the same package as the LD1 and in the optical path, and in the case of a high power semiconductor laser (30 mW or more) used for recording on a recordable optical disc, the latter is generally used. Target. A current proportional to the optical output obtained by the PD 2 is converted into a voltage by the current-voltage conversion circuit 5 and input to the error amplification circuit 6.

The error amplifier 6 is supplied with the set voltage switched by the mode selector switch 3b.
The current of each mode, which is compared with the output voltage of the current-voltage conversion circuit 5 and is controlled based on the error voltage output, is supplied from the current booster 9 to the LD 1, and the light output in each mode is kept constant.

In general, when a semiconductor laser is used as an optical system for an optical disk, the optical disk is irradiated with focused light and an information signal and a servo signal are obtained from the optical disk, so that the reflected light from the optical disk returns to the LD 1 side to some extent. Due to the amount of returned light to the LD 1 and the optical path length, scoop noise and mode hopping noise due to the interference of the returned light and the irradiation light are generated, which causes C / N deterioration of the reproduced signal. The generation of these noises is remarkable in a high-power semiconductor laser.

A high frequency superposition method is known to reduce the mode hopping noise and the like due to the return light.
In order to superimpose the high frequency current on the DC bias current of the LD1, the high frequency oscillation circuit 4 for generating the high frequency current is connected to the LD1 via the mode changeover switch 3a and the capacitor C1. Then, a high frequency current, for example, a high frequency current of 200 to 500 MHz is LD
1 to reduce the noise.

Next, at the time of recording by the APC circuit,
A signal based on a data modulation method such as a 1-7 modulation method (shortest domain length 2T, longest domain length 8T) is supplied from the recording signal generation circuit 8, and the amplitude of the laser current is passed through a current booster 9. Modulation is performed to obtain the peak light output required for recording.

By the way, there are an optical modulation system and a magnetic field modulation system as a recording system of the magneto-optical disk. Although the magnetic field modulation system can directly overwrite, it is not very suitable for the high transfer rate. In the trend of high density and high transfer rate, the optical modulation method is common. In fact, ISO (International Organization for Standardization) 5 ", 3.5", and 5 "double density are standardized by an optical modulation method.

The recording power control by this light modulation system is controlled so that the peak power in pulsed light emission becomes constant. However, the higher the transfer rate, the smaller the pulse width in pulsed light emission. In order to perform the optical output control, the PD 2, the current-voltage conversion circuit 5 and the error amplification circuit 6 in the APC circuit are required to have high-speed responsiveness, which is difficult to realize in terms of characteristics and cost.

Therefore, in the sector format of the ISO standard continuous servo tracking system which is becoming mainstream at present, as shown in FIG. 11, a test for setting a recording power level before recording data in one sector. An ALPC (Auto Laser Power Control) part, which is an area, is located in front of the data part (Data), and this ALPC part controls the peak power level of pulse emission during recording.

In the setting method, when the laser light output control circuit as shown in FIG. 10 is used, the ALPC section is turned on by direct current (the pulse width is longer than the recording pulse and can be regarded as direct current), and when the set power is reached. The laser driving voltage is held, and the data section is caused to perform pulsed light emission based on the held driving voltage, and the peak power of the pulsed light emission is controlled to be the set power in the ALPC section.

In FIG. 10, the laser light output control circuit includes LD1, PD2 for monitoring the light output of LD1, a current-voltage conversion circuit 5, a reproduction error amplifier 11 for inputting the output voltage of the current-voltage conversion circuit 5, and the same recording. Error amplifier 1
2 and erasing error amplifier 13, a holding circuit 14 that holds the error voltage of the recording error amplifier 12, a mode changeover switch 18 (reproduction R, recording W, erasing E), and amplifiers 15 and 16 that amplify the error output voltages. , 17 are provided. Then, on the output side of the amplifier circuits 15, 15, 17,
The voltage-current conversion circuit 1 is passed through the mode changeover switch 18.
9 are provided.

Further, the reproducing error amplifier 11 has a reproducing power setting voltage 20 and the recording error amplifier 12 has a recording power setting voltage 21a for a peak value APC or a recording power setting voltage 21b for an average value APC. The erasing error amplifier 13 is supplied with an erasing power setting voltage 22 for determining the optical output in each mode.

Further, the error output voltage in each mode selected by the mode changeover switch 18 and the output current of the voltage / current conversion circuit 19 for converting the data signal voltage of the recording signal generation / mode setting circuit 23 into a current are set. A current booster 24 for amplification is provided, and the output current of the current booster 24 is supplied to the LD1 so that the LD1 emits light in a predetermined manner.

The address decoder 26 is a circuit for reading out the address of the pre-format section on the optical disk, and the system controller 25 performs various controls based on the absolute address from the address decoder 26.

As the recording power setting voltage supplied to the recording error amplifier 12, the average value APC setting voltage 21b or the peak value APC setting voltage 21a is supplied. A
The average value detection method is performed by feedback APC as a PC, but in this case, the PD 2 and the current-voltage conversion circuit 5 that are normally used are subject to band limitation, so that the pulse is integrated and the average value APC of 1/2 of the peak value is used. Becomes

On the other hand, in the peak value detection method, feedback APC is also possible by using a PD having a band more than the shortest pulse width at the time of recording or a current-voltage conversion circuit, but it is expensive and not general, so it is usually used. Hold the peak value and apply open loop APC. That is, the direct current power corresponding to the peak power of the pulse is momentarily emitted by the feedback APC, the driving voltage based on the output voltage of the APC circuit at that time is held, and then pulse modulation is performed by the signal from the recording signal generation circuit. In this method, the LD1 is pulsed.

The recording operation of the optical output control circuit of FIG. 10 will be described below with reference to the format and time chart of FIG. When an optical pickup device (not shown) reads the address data from the address part and records this sector area, after the address data is read from the address part, it is based on the recording command signal from the system controller 25 at the timing of the ALPC part. The recording mode switch 18 is set to W, and the peak value A of the recording power setting voltage is set to A.
The PC setting voltage 21b is selected.

At the same time as this switching timing, a hold pulse (several μs) is supplied from the system controller 25 to the hold circuit 14. On the other hand, the current proportional to the optical output of the LD1 obtained by the PD2 is converted into a voltage by the current-voltage conversion circuit 5 and input to the recording error amplifier 12, so that the recording loop causes the LD1 to emit light. The output rises (DC lighting) so that the output becomes the optimum laser power determined by the set voltage 21a, and the output voltage of the recording error amplifier 12 at that time is the hold circuit 1.
Holds at 4.

Then, in accordance with a command from the system controller 25 for each sector, the switch 14a is turned on to reset the hold voltage.

That is, the APC loop is closed immediately before the data portion to be actually recorded (several μs), and the DC power is raised. This loop band is usually about 300 KHz (τ =
0.3 microseconds), and the laser power rises sufficiently after several μs (the head of the data section). Then, the voltage for outputting the laser power is held, and thereafter, the LD1 is driven with this hold value until the recording in the data portion of the sector is completed. That is, a few μ
The system controller 25 controls the hold circuit 14 and the switch 14a so that the closed loop is formed in the APC circuit only for s and the other is in the open loop.

This hold voltage is supplied to the voltage-current conversion circuit 19 via the switch 18, and the current booster 24 is supplied.
Drive current is supplied to the LD 1 from the above, and the optical output in the recording mode is kept constant. In this case, the hold circuit 14
A hold pulse for recording power detection is applied to the control input terminal of the
Supplied while passing through the LPC section.

This hold period (high level period of several μs) is a period considerably longer than the generation period of the laser pulse at the time of recording. In this sense, the hold circuit 14
The hold value of the recording power due to can be regarded as DC lighting. Although not shown, the erase power is similarly held and held during the hold period during erasing.

The ALPC unit usually takes about 1 to 4 μs in consideration of the response characteristics of the APC circuit, and varies depending on the data modulation method and transfer rate in the data area, but the shortest pulse width is 10 to 10 with the increase in transfer rate. 20ns is becoming the mainstream, but the light emission time in the ALPC part is still 1
There is a difference of more than 00 times.

Even if the optical output control circuit controls the optical output at the time of recording, the actual recording peak power is increased or decreased from the set power due to the pulse emission characteristics of the semiconductor laser.
There are still problems such as the case where the optimum recording is not performed and the DC life in the ALPC section affects the laser life.

In the semiconductor laser, a forward current is injected into the pn junction to form a population inversion, and the population inversion is changed by changing the injection current, and accordingly, the frequency of stimulated emission is changed and the laser light intensity is changed. It is possible to change and directly modulate by pulsed light emission, but in this pulsed light emission, a relaxation phenomenon appears in the light pulse and a resonance phenomenon appears in the frequency characteristic as a drawback.

A general equivalent circuit of a semiconductor laser is a parallel circuit of RLC as shown in FIG.
(Series resistance), Cd (parallel capacitance), Lw (lead wire inductance), Cp (package capacitance, sufficiently small to be ignored) exist, and LPF is determined by Lw and Cd.
(Low-pass filter) is formed, and in particular, Cd greatly differs depending on the structure of the laser and affects the modulation band of the laser.

As described above, there are many fluctuation factors in the pulse emission characteristics (light modulation characteristics) of the semiconductor laser, and even if the semiconductor lasers of the same type have different static characteristics, there is a possibility that they will also change due to variations between lots. . In the same type of semiconductor laser, if there is a difference in the pulse emission characteristics based on the above-mentioned fluctuation factors, there will be a difference between the peak power set and held in the ALPC section and the actual recording peak power in the data section. Will occur.

FIG. 7 shows some patterns of the difference between the peak power due to the direct current lighting set in the ALPC section and the recording peak power of pulsed light emission in the data section. FIG. 7A shows an example in which the peak power reduction of −ΔP ₀ occurs in the data area because the pulse emission band is not extended so much.

FIG. 7B shows an example in which the peak power increase of + ΔP ₀ occurs in the data area because the pulse emission band is sufficient and the transient response (relaxation oscillation) overshoots.

FIG. 7C shows a time constant curve of −Δ.
An example in which a peak power reduction (droop) of P ₀ occurs is shown.

FIG. 7D shows a certain time constant curve + Δ.
An example in which the peak power increase of P ₀ occurs is shown.

[0037]

In view of the above problems, the present invention provides a laser light output control circuit for compensating so as to eliminate the difference between the set recording peak power and the peak power at the time of actual pulse emission in the data section. Is in the point of providing.

[0038]

According to a first aspect of the present invention, there is provided a laser diode, a laser diode current supplying means, a laser light output detecting means for detecting an emission output of the laser diode, and a laser light output detecting means. And an APC circuit for controlling the laser diode current supply means on the basis of the output from the holding circuit, which comprises a comparing means for comparing the output and the set value of the light emission output and a holding circuit for holding the output of the comparing means. A laser light output control circuit for controlling the light emission output of the laser diode during recording based on the value held in the test area of the optical disc provided with the test area held by the hold circuit; The shortest repetitive pulse signal for recording is supplied to the laser diode and the comparison circuit And supplying the average value APC setting signal.

A second invention is a laser diode, a laser diode current supplying means, a laser light output detecting means for detecting a light emitting output of the laser diode, an output from the laser light output detecting means and a set value of the light emitting output. And APC for controlling the laser diode current supply means based on the output from the hold circuit.
A hold circuit for controlling the light emission output of the laser diode at the time of recording based on the value held in the test area of the optical disc having a test area held by the hold circuit. Is provided to correct the output voltage of the laser diode, the laser diode is turned on in the test region by direct current, and the peak value APC setting signal is supplied to the comparing means.

A third invention is to set a laser diode, a laser diode current supply means, a laser light output detection means for detecting the light emission output of the laser diode, and an output from the laser light output detection means and a light emission output. And an APC circuit for controlling the laser current supply means based on the output from the hold circuit.
In a laser light output control circuit for controlling the light emission output of the laser diode at the time of recording based on the value held in the test area of the optical disc having the test area held by the hold circuit, the laser diode current supply means is provided with a laser beam. It is characterized in that a time constant circuit for correcting the drove characteristic of the diode is switchably provided.

In the laser light output control circuit of each of the first to third inventions, the test area is the ALPC section of the sector format of the ISO standard continuous servo tracking system.

[0042]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The laser light output control circuit of the present invention will be described below with reference to the block diagram of FIG. 1 and the operation timing chart of FIG.

In the optical output control circuit of FIG.
The same reference numerals will be given to the portions where the configuration of 0 does not change. Further, since the object of the present invention is only the recording mode, the high frequency oscillation circuit necessary for reproduction is omitted.

The optical output control circuit of the present invention also includes LD1, LD
PD2 for monitoring the optical output of 1 and mode changeover switch 18
(Reproduction R, recording W, erasing E), current-voltage conversion circuit 5, error amplifiers 11 to 13 in each mode for inputting the output voltage of the current-voltage conversion circuit 5, set voltage 20 to determine the optical output in each mode 22, hold circuit 14, reset switch 14a, amplifiers 15 to 17, voltage / current conversion circuit 19, recording signal generation / mode setting circuit 23, current booster 24,
The system controller 25 and the address decoder 26 are provided.

Since the above-mentioned configuration does not change the configuration of the light output control circuit of FIG. 10, detailed description thereof will be omitted, and the features of the present invention will be described in detail.

In addition to the above configuration, the optical output control circuit of the present invention is connected to the output side of the hold circuit 14 such that a hold voltage correction addition / subtraction circuit 27 for correcting the hold voltage and a current booster 24 can be turned on / off by a switch 28a. A time constant circuit 28 is provided. The output of the hold circuit 14 is
The voltage is corrected by the hold voltage correction addition / subtraction circuit 27, amplified by the amplifier 16, supplied to the voltage / current conversion circuit 19 via W of the mode changeover switch 18, and converted into a current. Then, the converted current is amplified by the current booster 24 and supplied to the LD 1 as a drive current.

The laser power compensation operation in this optical output control circuit will be described below with reference to the format and timing chart shown in FIG. FIG. 2A shows the I
The SO standard sector format is simply shown, address information is recorded in the address portion, and the absolute address is recognized by the address decoder 26 in the reproduction mode. Further, the ALPC portion is a part of the ISO standard sector format ODF area, but other areas are omitted in this format.

FIG. 2B shows the mode, in which the switch 18 is switched to the reproduction mode in the address part and to the recording mode W in the ALPC part and the data part. Further, in the following description, it is assumed that the track to be recorded has already been erased.

In this optical output control circuit, in the recording mode, the ALPC section generates a drive voltage (C) based on the average value APC set voltage or the peak value APC set voltage, and when the set power is reached. The output voltage of the error amplifier 12 is held by the hold circuit 14,
The hold voltage and the pulse output from the recording signal generation circuit 23 are used for pulse emission, and the pulse emission as shown in FIG. 2D is compensated for.

Next, in order to solve the above problems, the operation when the hold voltage correction addition / subtraction circuit 27 and the time constant circuit 28, which are the features of the present invention, are provided, (E) to (F) of FIG. The timing chart will be described.

The laser drive voltage shown in FIG. 2E is A
Set the recording power in the LPC section to the peak value A of direct current lighting.
In the case of -ΔP ₀ , the output voltage of the hold circuit 14 is shown by the PC and the correction voltage corresponding to the offset optical output of ± ΔP ₀ (FIG. 7) is added to or subtracted from the output voltage of the hold circuit 14. Adds (a), +
In the case of ΔP ₀ , subtraction (b) is performed and correction is performed so that the peak power in pulse emission becomes the same as the peak power set in the ALPC section.

Next, the compensation of the drove characteristic of the de light output shown in FIG. 7C will be described. In this case, as shown in (c) of FIG. 2 (F), the set power in the ALPC section is set to the peak value APC of DC lighting, and the hold voltage correction addition / subtraction circuit is added to the output voltage of the hold circuit 14. At 27, a correction voltage corresponding to the optical output of −ΔP ₀ (c in FIG. 7) is added.

On the other hand, since the driving voltage is excessively added in the portion corresponding to the light output showing the drove characteristic by the addition of the correction voltage, the time constant circuit 28 provided in the current booster 24 is switched to the switch 28a. When turned on, the drive current due to the excessively added drive voltage is reduced based on the time constant corresponding to the drove characteristic, and the offset light output −ΔP ₀ exhibiting the drove characteristic is corrected.

When correcting the optical output of the drove characteristic shown in FIG. 7 (d), the set power in the ALPC section is set at the peak value APC of direct current lighting, and then, in (d) of FIG. 2 (F). As shown in FIG. 6, without adding or subtracting the correction voltage to the output voltage of the hold circuit 14, that is, the hold voltage correction addition / subtraction circuit 27 is omitted, and only the time constant circuit 28 is turned on to drive the drive current. The offset light output + ΔP ₀ indicating the drove characteristic is corrected by reducing the time constant corresponding to the drove characteristic.

In the above embodiment, the hold voltage correction addition / subtraction circuit 27 and the time constant circuit 28 are provided to correct the optical output. In the following example, the hold voltage correction addition / subtraction circuit 27 and the time constant circuit 28 are used. This is a correction method when the configuration of FIG. 10 is used as it is without being provided.

As shown in FIG. 2G, the laser driving voltage is the average value APC during pulse lighting in the ALPC section.
Then, as will be described later (FIG. 6), the ALPC section generates the shortest repetitive pulse in the data section to perform pulse lighting.

In other words, in the ALPC section, the recording signal generating / mode setting circuit 23 generates a pulse voltage which becomes the shortest repetitive pulse of the recording data and supplies it to the LD1, and at the shortest repetitive pulse, the photodiode PD2 and the current are supplied. Since the band of the voltage conversion circuit 5 is insufficient, the voltage conversion circuit 5 is operated at the average value APC (1/2 of the peak power). Then, the APC of the actual recording power in the data section after that is also subjected to the average value APC with the hold voltage set in the ALPC section to eliminate the difference from the set value.

This method corrects the optical output characteristics shown in FIG. 7 by making the ALPC section and the data section have the same modulation characteristics so that the peak powers of the ALPC section and the data section are the same. is there.

The light output control circuit according to the block diagram will be further described below based on a specific circuit. In the circuit, the APC circuit is shown as a block APC circuit 30.

In FIG. 3, transistors Q1, Q2,
A differential switching laser drive circuit is configured by Q3, Q4, and Q5. In this differential switching laser drive circuit, the transistors Q3 and Q4 form a current mirror circuit, and the drive current is supplied to the LD1 from the collector of the transistor Q4.

Of the transistors, the transistor Q
1-Q4 voltage-current conversion circuit 19 and current booster 2
4 and the current of the current booster is controlled by the transistor Q5. As shown in the waveform diagram of FIG. 4, the D output from the recording signal generation / mode setting circuit 23 is supplied to the base of the transistor Q2, and the inverted D (D bar) output is supplied to the base of the transistor Q1. When the D output or the inverted D output is at a high level (H), the transistor Q2 or the transistor Q1 is turned on and each mode is set.

When the D output is at a high level and the transistor Q2 is turned on, the collector current of the transistor Q4 flows into the LD1 and the photocurrent proportional to the light output obtained from the PD2 is converted into a voltage by the current-voltage conversion circuit 5. Convert and AP
In the C circuit 30, the hold voltage held in the ALPC section is applied to the base of the transistor Q5 to control the collector current of the transistor Q4, that is, the drive current supplied to the LD1.

When the LD1 is lit by direct current (in the reproducing and erasing modes), the D output is set to the high level (H), the inverted D output is set to the low level (L), and the pulse is lit (during recording). The D output and the inverted D output are pulse-modulated with a signal according to the recording modulation format.

In such a light output control circuit, as shown in FIG.
To correct the Dorubu characteristics of -DerutaP ₀ of the light output shown in, shows an example of connecting the time constant circuit 28 to the emitter of the transistor Q4. In FIG. 3, the hold voltage correction addition / subtraction circuit 27 and the hold circuit 14 are included in the APC circuit 30.

Further, the time constant circuit 28 includes a capacitor C1.
And a resistor R1 are connected in series in this order, and are turned on and off by a switch 31. When correcting the drove characteristic, the switch 31 is turned on in the recording mode to connect the time constant circuit 28 to the emitter of the transistor Q4 to correct the drove characteristic.

Next, without adding the hold voltage adder / subtractor circuit 27 and the time constant circuit 28, the circuit shown in FIG. 10 is used as it is for the peak power set in the ALPC section and the pulse emission in the data section. An example of eliminating the difference from the peak power of 1 will be described with reference to FIGS.

As shown in FIG. 7, when the driving voltage is set at the peak value APC with the DC lighting in the ALPC section, the laser power for pulse emission in the data section is not the optimum power set in the ALPC section. Shows a decrease in power. Therefore, without turning on the direct current in the ALPC section,
Light is emitted with the shortest repetitive pulse of data, and the average value A
Perform a PC.

In the circuit of FIG. 3, the time constant circuit 28 is turned off, and as shown in FIG. 6, the recording signal generation / mode setting circuit 23 generates the shortest repetitive pulse for the D output and the inverted D output in the ALPC section to generate the ALPC section. The LD1 is pulse-emitted in the section and the average value APC is performed. Then
In the ALPC section of the LD1, the laser power rises toward the peak value as shown in FIG. Even if the drive voltage corresponding to the peak value at this time is held and then the pulse light emission at the time of recording is performed in the data portion, the pulse light emission in the ALPC portion can continue the pulse light emission in the data portion as well, so it is set in the ALPC portion. It is possible to eliminate the increase and decrease of the peak value.

[0069]

According to the present invention, since the set recording power in the ALPC section and the actual recording peak power can be corrected so that optimum recording can be performed, compatibility between recording media and driving devices can be achieved. Is easy to take. In particular, the invention of claim 1 can reduce the influence on the life of the laser diode, and further, the optimum recording can be performed inexpensively without the need for special elements such as a high-speed laser emission output monitor diode and a high-speed slew rate current-voltage conversion circuit. Is possible.

[Brief description of drawings]

FIG. 1 is a block diagram of a laser light output control circuit of the present invention.

FIG. 2 is an example of an operation timing chart of the laser light output control circuit of the present invention.

FIG. 3 is a circuit diagram of a main part of a laser light output control circuit of the present invention.

FIG. 4 is an operation explanatory diagram of a main part circuit diagram of the laser light output control circuit of the present invention in FIG. 3;

FIG. 5 is a waveform diagram illustrating a problem in recording in a conventional laser output control circuit.

FIG. 6 is a waveform diagram illustrating the operation of the laser output control circuit of the present invention.

FIG. 7 is a waveform diagram illustrating the difference between the set power of the conventional laser light output control circuit and the power during recording.

FIG. 8 is an equivalent circuit diagram of a laser diode.

FIG. 9 is a general operation waveform diagram for explaining a laser light output control circuit.

FIG. 10 is a block diagram of a laser light output control circuit used in an embodiment of the present invention.

FIG. 11 is a sector format of an ISO standard continuous servo tracking system.

FIG. 12 is a block diagram of a conventional laser light output control circuit.

[Explanation of symbols]

 1 Laser Diode 2 Photodiode 5 Current Voltage Converter 12 Recording Error Amplifier 14 Hold Circuit 21a Recording Power Setting Voltage (Peak Value APC) 21b Recording Power Setting Voltage (Average Value APC) 27 Hold Voltage Correction Addition / Subtraction Circuit 28 Time Constant Circuit

Front page continuation (72) Inventor Seiji Oura 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (8)

[Claims] 1. A laser diode, a laser diode current supply means, a laser light output detection means for detecting a light emission output of the laser diode, and an output from the laser light output detection means and a set value of the light emission output are compared. And a hold circuit for holding the output of the comparison means, and an APC circuit for controlling the laser diode current supply means based on the output from the hold circuit, and a test area held by the hold circuit. In the laser light output control circuit for controlling the light emission output of the laser diode at the time of recording based on the value held in the test area of the provided optical disc, the shortest repetitive pulse signal of the data at the time of recording to the laser diode in the test area. Along with supplying
A laser light output control circuit, wherein an average value APC setting signal is supplied to the comparison means. 2. The laser light output control circuit according to claim 1, wherein the test area is an ALPC section of an ISO standard continuous servo tracking type sector format. 3. A laser diode, a laser diode current supply means, a laser light output detection means for detecting a light emission output of the laser diode, and an output from the laser light output detection means and a set value of the light emission output are compared. And a hold circuit for holding the output of the comparison means, and an APC circuit for controlling the laser diode current supply means based on the output from the hold circuit, and a test area held by the hold circuit. In the laser light output control circuit for controlling the light emission output of the laser diode during recording based on the value held in the test area of the provided optical disc, a correction circuit for correcting the output voltage of the hold circuit is provided. Characteristic laser light output control circuit. 4. The laser light output control circuit according to claim 3, wherein the test area is an ALPC section of a sector format of an ISO standard continuous servo tracking system. 5. The laser light output control circuit according to claim 3, wherein in the test area, the laser diode is turned on by direct current and a peak value APC setting signal is supplied to the comparison means. . 6. A laser diode, a laser diode current supply means, a laser light output detection means for detecting a light emission output of the laser diode, and an output from the laser light output detection means and a set value of the light emission output are compared. And a hold circuit for holding the output of the comparison means, and an APC circuit for controlling the laser current supply means based on the output from the hold circuit, and a test area held by the hold circuit is provided. In a laser light output control circuit for controlling the light emission output of the laser diode at the time of recording based on the value held in the test area of the optical disc, a time constant circuit for correcting the drove characteristic of the laser diode in the laser diode current supply means. A laser light output control circuit characterized by being provided so as to be switchable. 7. The laser light output control circuit according to claim 6, wherein the test area is an ALPC section of a sector format of the ISO standard continuous servo tracking system. 8. The laser light output control circuit according to claim 6, further comprising a correction circuit for correcting the output voltage of the hold circuit.