JP2003124565A - Light emitting element controller and optical recorder/ reproducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting element controller and an optical recorder/ reproducer in which a light emitting element can be protected surely against damage and deterioration by controlling a drive voltage being applied to the light emitting element. SOLUTION: When a semiconductor laser 32 is driven by a current amplifying means 34 by determining an operating drive voltage being applied thereto by an operating means 39 and the driving state of the semiconductor laser 32 is switched by a switch means 49 from a first state for driving with a first drive voltage to a second state for driving with a second drive voltage higher than the first drive voltage, a mono-multivibrator 40 interrupts driving by a first control means 37 and a switch means 41 brings the drive voltage by the first control means 37 to zero during the interruption period. At the time of switching from reproduction mode to recording mode, a voltage lower than the second drive voltage is applied to the semiconductor laser 32 based only on the driving by a second control means 38 for controlling the drive voltage based on a command quantity of light thus protecting the semiconductor laser 32 against damage and deterioration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for controlling the amount of light emitted from a light emitting element which is provided in a device and is used as a light source, and the light emitted from the light emitting element controlled by the control device. The present invention relates to an optical information recording / reproducing device such as an optical disk device for reproducing and recording data.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing an electrical configuration of a conventional light emitting element control device 1. The light emitting element control device 1 uses the current amplification circuit 2 to form the semiconductor laser element 3
Are driven to emit a light beam from the semiconductor laser element 3. Based on the mode signal h from the mode command means 4 and the modulation signal i from the information input means 5, a drive voltage is applied from the second control circuit 6 to the adder 7, and a reproduction mode reference voltage is applied according to each mode. The reference value given by the source 8 and the recording mode reference voltage source 9 and the voltage value corresponding to the light quantity of the light beam detected by the photodetector 10 are compared and calculated by the differential amplifier 11, and the emitted light quantity corresponding to the reference value. The drive voltage is supplied from the first control circuit 12 to the adder 7 so that The adder 7 performs an addition operation on the drive voltages from the first control circuit 12 and the second control circuit 6 and supplies the result to the current amplification circuit 2 to drive the semiconductor laser element 3. In such a light emitting element control device 1, since the detection value by the photodetector 10 contains noise, it is constituted by the resistance element 13 and the capacitor 14 between the differential amplifier 11 and the first control circuit 12. A low pass filter is provided to remove noise.

[0003]

The applicant of the present invention has proposed, in Japanese Patent Application No. 2000-212356, a semiconductor laser control device which realizes high speed in pulse driving of a semiconductor laser in a circuit configuration with a single single-sided positive power supply. ing. This semiconductor laser control device drives a semiconductor laser by using a faster NPN transistor instead of a PNP transistor so as to pulse-drive a semiconductor laser element at high speed. Japanese Patent Application 2000
If it is directly adopted in the semiconductor laser control device shown in FIG. 211213, when the reproduction mode is switched to the recording mode, the emitted light quantity in the reproduction mode for a certain period is a very high output light quantity with a pulse component added.

In FIG. 5, in the light emitting element control device 1, the semiconductor laser element 3 is switched from the reproduction mode to the recording mode.
4 is a graph showing an example of changes in the value indicated by each signal when driving the. 5 (1) shows the relationship between the mode signal h and the time, FIG. 5 (2) shows the relationship between the operation control signal k and the time, and FIG. 5 (3) shows the emitted light amount b and the time. Shows the relationship. In the light emitting element control device 1, in the reproduction mode, that is, in the period in which the mode signal h is a signal indicating the L level as shown in FIG.
By the feedback control of the control system including
As shown in (2), the operation control signal k becomes a signal indicating a DC voltage. As a result, the emitted light amount b of the semiconductor laser 3
Is controlled so as to have a predetermined light amount Pr in the reproduction mode, as shown in FIG.

When switching from the reproduction mode to the recording mode,
The pulse-shaped second control signal j corresponding to the modulation signal i is added to the signal of the control system including the first control circuit 12,
As shown in (2), the operation control signal k has a pulsed waveform. Since the semiconductor laser drive current a based on the operation control signal k has a pulse-shaped waveform, the semiconductor laser device 3
Emits pulsed light. Light emission amount b of the semiconductor laser device 3
Has a pulse-like waveform with peak power Pw and bottom power 0, as shown in FIG.

Immediately after switching from the reproduction mode to the recording mode, the operation control signal k supplied to the current amplification circuit 2 is set to a voltage controlled so as to obtain the light amount Pr in the conventional reproduction mode. Since the voltage becomes a voltage to which a pulsed voltage is added, the emitted light amount b becomes an excessive light amount Pwmax that is much larger than the peak power Pw. Photo detector 1
0 is the excess light amount Pwma larger than the peak power Pw
After detecting x, feedback control is performed so that the peak power Pw is obtained. After that, the emitted light amount b is
The semiconductor laser drive current a is gradually reduced according to the response time determined by the frequency band of the control system including the first control circuit 12, and is controlled to the semiconductor laser drive current a according to the peak power Pw of the emitted light amount b.

In such a light emitting element control device 1, since the low-pass filter constituted by the resistance element 13 and the capacitor 14 includes the capacitance component C, the capacitor 1 is switched when the reproduction mode is switched to the recording mode.
The voltage due to the electric charge stored in 4 is given to the first control circuit 12, and the drive voltage obtained by adding the drive voltage by the first control circuit 12 and the drive voltage by the second control circuit 6 is the semiconductor laser element 3 Will be higher than the rated withstand voltage. As a result, the semiconductor laser element 3 is driven at a voltage higher than the withstand voltage, and the semiconductor laser element 3 is damaged. Therefore, immediately after switching from the reproduction mode to the recording mode, the semiconductor laser drive current a such that the emitted light amount becomes the excess light amount Pwmax is
Since the rated withstand driving voltage of the semiconductor laser element 3 is far exceeded, when the semiconductor laser driving current a that causes the emitted light quantity to become the excessive light quantity Pwmax is given to the semiconductor laser element 3,
The semiconductor laser element 3 may be damaged in an instant, and even if it is not damaged, the characteristics of the semiconductor laser element 3 are significantly deteriorated, which causes a serious problem. The high-output light emission immediately after switching from the reproduction mode to the recording mode emits light regardless of the frequency band handled by the control system including the first control circuit 12, so that the amount of light emitted from the semiconductor laser element 3 is forced. There was a problem that had to be limited to.

As another conventional technique, Japanese Patent Laid-Open No. 11-18
There is a device as shown in 5274. In this device, when the recording mode is switched to the reproduction mode,
The drive voltage applied to the semiconductor laser device is controlled so as not to increase. In such a device, when the recording mode is switched to the reproducing mode, the signal given to the first control circuit is sufficient to emit a light beam from the semiconductor laser element along with the change of the signal corresponding to the modulation signal. Since the voltage does not reach such a high voltage, no light beam is emitted from the semiconductor laser device. Further, since the frequency band for controlling the amount of light emitted from the semiconductor laser element is usually about several tens [kHz] to several hundreds [kHz], several [μsec] immediately after switching from the recording mode to the reproduction mode During a period of several tens of microseconds, the semiconductor laser element is naturally in a non-light emitting state. Therefore, the light-emitting element control disclosed in JP-A-11-185274 has low required accuracy.

Further, in the device disclosed in Japanese Patent Laid-Open No. 11-185274, the high output light emission generated when switching from the recording mode to the reproduction mode does not exceed the range used within the rating of the semiconductor laser device, and the high output light emission is performed. However, since the semiconductor laser device is used within the rated range, the characteristics of the semiconductor laser device are not significantly deteriorated. Further, in this device, by setting the frequency band of the control system including the first control circuit to be high, the delay of this control system can be shortened, so that the delay of the control of the emitted light amount accompanying the switching from the recording mode to the reproduction mode is suppressed. It can be greatly shortened. Therefore, the same effect can be realized without using the second control circuit. In this way, when switching from the recording mode to the reproduction mode, light is emitted so that the emitted light amount is slightly larger than the emitted light amount from the semiconductor laser element in the reproduction mode.
The problem is not the drive that damages the semiconductor laser device, but the voltage applied to the semiconductor laser device immediately after switching from the reproduction mode to the recording mode. JP-A-11-
185274 is not configured to control the semiconductor laser device that suppresses the emitted light amount when switching from the reproduction mode to the recording mode.

Therefore, an object of the present invention is to provide a light emitting element control device and an optical recording / reproducing apparatus which can reliably prevent damage and deterioration of the light emitting element by controlling the drive voltage applied to the light emitting element.

[0011]

The present invention provides at least the following:
A light-emitting element control device for driving a light-emitting element by switching between a first state of driving with a first driving voltage set in advance and a second state of driving with a second driving voltage higher than the first driving voltage. A detection means for detecting the amount of light emitted from the light emitting element, a first control means for controlling a drive voltage applied to the light emitting element based on the detection result of the detection means, and a command light amount for instructing the amount of light emitted from the light emitting element. Based on the first control means, the first drive voltage is applied to the light emitting element so as to apply the first drive voltage when in the first state, and the second drive voltage is applied when in the second state. 2 a calculation means for calculating a calculation drive voltage to be applied to the light emitting element based on each drive voltage by the control means, a drive means for supplying the calculation drive voltage to the light emitting element by the calculation means for driving, and a drive state of the light emitting element Condition And a switching means for switching between the second state and the second state. When switching the driving state of the light emitting element from the first state to the second state, the driving of the light emitting element based on the control of the first control means is temporarily stopped, and then the first state. It is a light-emitting element control device including a third control means for restarting driving based on the control of the control means.

According to the invention, when the drive state of the light emitting element is switched from the first state to the second state by the switching means, the third control means temporarily drives the light emitting element based on the control of the first control means. After the stop, control is performed so as to restart the drive based on the control of the first control means. As a result, when the first state is switched to the second state, the light emitting element is driven only based on the control of the second control means. Therefore, immediately after the switching to the second state, the driving by the first control means is performed. The calculation driving voltage applied to the light emitting element can be suppressed to be low without being affected. Accordingly, the driving unit can drive the light emitting element without damaging the light emitting element without applying a voltage higher than the second driving voltage to the light emitting element. Therefore, in the second state, it is possible to prevent the light emitting element from being damaged or deteriorated due to the driving unit applying a voltage higher than the second driving voltage to the light emitting element.

Further, according to the present invention, the third control means, when the driving of the light emitting element based on the control of the first control means is stopped, is the transfer function in the transfer system from the detection means to the first control means. It is characterized by decreasing the constant.

According to the present invention, the time constant of the transfer function in the transfer system from the detection means to the first control means is reduced while the driving of the light emitting element based on the control of the first control means is stopped. . As a result, after the driving based on the control of the first control unit is restarted, it is possible to give the light emitting element an arithmetic drive voltage that becomes the emitted light quantity corresponding to the command light quantity at an early stage. Therefore, even if the driving state of the light emitting element is switched, the second driving voltage in the second state can be applied to the light emitting element to drive it within a short period after switching, and the light emitting element can be reliably damaged. It can be prevented and driven.

According to the present invention, the driving voltage applied to the light emitting element is substantially the same as the second driving voltage or less than the second driving voltage while the driving of the light emitting element based on the control of the first control means is stopped. Is characterized in that.

According to the invention, by the third control means,
During the period in which the driving of the light emitting element based on the control of the first control unit is stopped, the calculation driving voltage applied to the light emitting element by the driving unit is set to the second driving voltage or less. In this way, the driving unit can reliably drive the light emitting element while preventing damage to the light emitting element without applying a high voltage to the light emitting element.

Further, according to the present invention, a switch for reducing the drive voltage applied to the light emitting element to zero under the control of the first control means while the driving of the light emitting element under the control of the first control means is stopped. It is characterized by having means.

According to the invention, the switch means sets the drive voltage applied to the light emitting element to zero under the control of the first control means. As described above, during the period in which the driving of the light emitting element is stopped based on the control of the first control means immediately after the driving state of the light emitting element is switched from the first state to the second state, the arithmetic means is the second control means. The calculation drive voltage is obtained based only on the control by and is given to the drive means. After that, the arithmetic means obtains the arithmetic drive voltage based on the drive voltage under the control of the first and second control means and gives it to the drive means. As a result, when the driving by the first control means is restarted, the first
The drive voltage by the control means is zero and changes as necessary. Therefore, the driving unit can drive the light emitting element while preventing damage without applying a voltage higher than the second driving voltage to the light emitting element.

The present invention also provides a first light-emitting element, which is predetermined.
The information is reproduced from the recording medium by driving in the first state where the driving voltage is applied, and the light emitting element is driven in the second state where the second driving voltage higher than the first driving voltage is applied to record the information in the recording medium. An optical recording / reproducing apparatus, which detects a light amount emitted from a light emitting element, and controls a drive voltage applied to the light emitting element based on a detection result of the detecting means.
Light emission based on the control means, the second control means for controlling the drive voltage given to the light emitting element based on the command light quantity for instructing the light emission quantity from the light emitting element, and the respective drive voltages by the first and second control means First, a calculation unit that obtains a calculation driving voltage to be applied to the element, a driving unit that applies the calculation driving voltage by the calculation unit to the light emitting element to drive the light emitting element, and a driving state of the light emitting element are first.
Switching means for switching between the state and the second state, and when switching the driving state of the light emitting element from the first state to the second state, after temporarily stopping the driving of the light emitting element based on the control of the first control means, An optical recording / reproducing apparatus including a third control means for restarting the drive based on the control of the first control means.

According to the invention, when the driving state of the light emitting element is switched from the first state to the second state by the switching means, the third control means temporarily drives the light emitting element based on the control of the first control means. After the stop, control is performed so as to restart the drive based on the control of the first control means. As a result, when the first state is switched to the second state, the light emitting element is driven only based on the control of the second control means. Therefore, immediately after the switching to the second state, the driving by the first control means is performed. It can be kept low without being affected. Accordingly, the driving unit can drive the light emitting element without damaging the light emitting element without applying a voltage higher than the second driving voltage to the light emitting element. Therefore, in the second state, it is possible to prevent damage and deterioration of the light emitting element caused by the driving means applying a voltage higher than the second driving voltage to the light emitting element, and it is possible to perform recording and reproduction.
The durability of the optical recording / reproducing apparatus can be increased.

[0021]

1 is a block diagram showing an electrical configuration of a light emitting element control device 31 according to an embodiment of the present invention. The optical recording / reproducing device 30 is a device that reproduces information from an optical disc (not shown) that is a recording medium and records information on the optical disc.
It is configured to include. Recording information on an optical disc includes recording no information, and thus erasing information from the optical disc.

The light emitting element control device 31 is a device for controlling the voltage applied to the light emitting element so that the amount of the light beam emitted from the light emitting element, that is, the amount of light emitted from the light emitting element becomes a predetermined light amount. The light emitting element control device 31 is
Semiconductor laser element 32, photodetector 33, current amplification means 3
4, mode command means 35, information input means 36, first control means 37, second control means 38, arithmetic means 39, mono-multivibrator 40, switch means 41, current-voltage conversion means 42, reproduction mode reference voltage source 43, The recording mode reference voltage source 44, the differential amplification means 45, the first resistance element 46, the second resistance element 47, the capacitor 48, the switching means 49 and the inverter 52 are included.

The semiconductor laser element 32, which is a light emitting element, is
It is an element (hereinafter simply referred to as “semiconductor laser”) that emits light with a light amount corresponding to the voltage value when a voltage is applied. The photodetector 33 is a detection unit that detects the amount b of light emitted from the semiconductor laser 32, and detects the amount b of light emitted from the semiconductor laser 32. The current amplifying means 34 is a driving means for applying a voltage to the semiconductor laser 32 to drive it, and a driving voltage for driving the semiconductor laser 32 by processing such as amplifying the arithmetic driving voltage from the calculating means 39. In other words, the semiconductor laser drive current a corresponding to the drive voltage is applied to the semiconductor laser 32 to drive it.

The mode command means 35 is a semiconductor laser 32.
Is a means for giving a mode command for instructing the drive mode of. The information input means 36 is means for inputting information to be recorded on the optical disc, and is means for outputting a modulated signal indicating the information.

The first control means 37 is means for controlling the drive voltage applied to the semiconductor laser 32 based on the detection result from the photodetector 33. Based on the mode command, the second control means 38 applies a drive voltage to the semiconductor laser 32 so as to apply the first drive voltage when in the first state and the second drive voltage when in the second state. Control. The first state is the driving state of the semiconductor laser 32 in the reproduction mode for reproducing information from the optical disc. Second
The state is the driving state of the semiconductor laser 32 in the recording mode for recording information on the optical disc. The first drive voltage is a drive voltage for driving the semiconductor laser 32 when reproducing information from the optical disc, and is a drive voltage corresponding to the command light amount in the reproduction mode. The second drive voltage is a drive voltage for driving the semiconductor laser 32 when recording information on the optical disc, is a drive voltage higher than the first drive voltage, and corresponds to the command light amount in the recording mode. Drive voltage.

The arithmetic means 39 is means for obtaining an arithmetic drive voltage to be given to the semiconductor laser 32 based on the drive voltages of the first and second control means 37 and 38. The mono-multivibrator 40 is third control means for controlling the driving of the semiconductor laser 32 based on the control of the first control means 37, and switches the driving state of the semiconductor laser 32 from the first state to the second state. At this time, after the driving of the semiconductor laser 32 based on the control of the first control means 37 is once stopped, the driving based on the control of the first control means 37 is restarted. The mono multivibrator 40 includes the first control means 37.
The time constant of the transfer function in the system from the photodetector 33 to the first control means 37 is decreased during the period in which the driving of the semiconductor laser 32 based on the control of 1 is stopped. The switch means 41 is a means for making the voltage applied to the first control means 37 zero under the control of the third control means 40 in order to stop the driving of the semiconductor laser 32 under the control of the first control means 37. .

The current-voltage converting means 42 is means for converting a given current into a voltage corresponding thereto. The reproduction mode reference voltage source 43 is a voltage source that gives a predetermined DC voltage. The voltage value of the reproduction mode reference voltage source 43 is the same as the voltage value of the drive voltage and the voltage value of the first drive voltage corresponding to the command light amount to be emitted in the reproduction mode. When the emitted light amount b from the semiconductor laser 32 is the same as the command light amount in the reproduction mode, the operation drive voltage given to the semiconductor laser 32 is the reproduction mode reference voltage source 43.
And the voltage value are the same.

The recording mode reference voltage source 44 is a voltage source that gives a predetermined DC voltage. The voltage value of the recording mode reference voltage source 44 is the same as the voltage value of the driving voltage and the voltage value of the second driving voltage corresponding to the command light amount to be emitted in the recording mode. When the emitted light amount b from the semiconductor laser 32 is the same as the command light amount in the recording mode, the operation drive voltage applied to the semiconductor laser 32 has the same voltage value as the voltage of the recording mode reference voltage source 44.

The differential amplifying means 45 has two input terminals, calculates the difference between the two input values, amplifies and outputs. In the first resistance element 46, the current is the first resistance element 46.
When the current flows to the second resistance element 47, the second resistance element 47 is an electric resistance that drops only a voltage corresponding to the resistance value R1 when the current flows to the second resistance element 47. Is the electrical resistance that causes the drop. The capacitor 48 has a capacitance C, and can store charges based on this capacitance C and the voltage applied. The capacitor 48 stores an electric charge according to the electrostatic capacitance C in a state where it is not short-circuited by the switch means 41, and both ends of the capacitor 48 are short-circuited by the switch means 41 to discharge the stored electric charge.

The switching means 49 is a means for switching the driving state of the semiconductor laser 32, and switches the driving state of the semiconductor laser 32 between the first state and the second state. The changeover unit 49 is configured to include a changeover switch 50 and a gate circuit 51. The changeover switch 50 is for each reference voltage source 4
A gate circuit 5 for switching between 3, 44
Reference numeral 1 is an electric circuit that outputs a signal obtained by inverting the polarity of the output signal of the AND circuit, which is a logical product circuit, and has two input terminals and one output terminal.

The gate circuit 51 outputs a signal indicating an H level when two signals indicating an L level are applied to the two inputs, and outputs a signal indicating an L level and a signal indicating an H level to the two inputs. When given, the noise removal signal g indicating H level is output, and when signals indicating H level are respectively applied to the two inputs, a signal indicating L level is output. For example, when the signal indicating the L level is the signal indicating the value of 0 and the signal indicating the H level is the signal indicating the value of 1, the signals indicating the value of 0 are applied to the two inputs of gate circuit 51, respectively. When a signal indicating a value of 1 is output, a signal indicating a value of 0 and a signal indicating a value of 1 are given to the two inputs, a signal indicating a value of 1 is output, and When a signal showing a value of 1 is given to each input, a signal showing a value of 0 is output.

The inverter 52 is an electric circuit having one input terminal and one output terminal and performing a negative logical operation. The polarity of the input signal is inverted with respect to a given input signal. Output a signal. The inverter 52 outputs a signal indicating an H level when a signal indicating an L level is applied to its input, and outputs a signal indicating an L level when an input signal indicating an H level is applied. For example L
When the signal indicating the level is a signal indicating the value of 0, the signal indicating the H level is a signal indicating the value of 1, and a signal indicating the value of 0 is given to the input of the inverter 52, A signal indicating a value is output, and when a signal indicating a value of 1 is given to the input, a signal indicating a value of 0 is output.

The commanding mode includes a reproducing mode and a recording mode. When the semiconductor laser 32 is driven in either the reproducing mode or the recording mode, the mode commanding means 35 is a mode commanding signal. The mode signal h is applied to the changeover switch 50, one input terminal of the gate circuit 51, and the mono-multivibrator 40, respectively. The mode instructing means 35 gives a signal indicating the L level as the mode signal h in the reproducing mode, and gives a signal indicating the H level in the recording mode as the mode signal h.

When the mode signal h is an L level signal, the changeover switch 50 sets the mode signal h to the state 50a in which one input terminal of the differential amplifying means 45 and the reproduction mode reference voltage source 43 are connected. Is a signal indicating the H level, the state 50b in which one input terminal of the differential amplifier 45 and the recording mode reference voltage source 44 are connected is set.

When one input terminal of the differential amplifying means 45 and the reproduction mode reference voltage source 43 are connected by the changeover switch 50, the reproduction mode reference voltage source 43 shows a predetermined DC voltage in the reproduction mode. Reference voltage signal
e is applied to the differential amplification means 45. When one input terminal of the differential amplifier 45 and the recording mode reference voltage source 44 are connected by the changeover switch 50, the recording mode reference voltage source 44 outputs a reference voltage signal indicating a predetermined DC voltage in the recording mode. e is applied to the differential amplification means 45.

The information inputting means 36 gives to the inverter 52 a modulation signal i obtained by modulating the information to be recorded on the optical disk. The modulation signal i is a signal corresponding to the information recording method, and is, for example, a signal having a single frequency and a predetermined pattern, and a signal indicating at least one of H level and L level. When the information input means 36 gives the modulated signal i to the inverter 52, the inverter 52
The polarity of the modulation signal i is inverted, that is, the L level is inverted to the H level, the H level is inverted to the L level, and the result is supplied to the other input terminal of the gate circuit 51. The mode command means 3 is provided at one input terminal of the gate circuit 51.
The mode signal h from 5 is applied, and the modulation signal i with the polarity inverted is applied to the other input terminal.

When the mode signal h from the mode instructing means 35 is a signal indicating the L level, the gate circuit 51
Based on the mode signal h indicating the L level and the modulation signal i whose polarity is inverted, the second control means 3 outputs the signal indicating the H level.
When the signal is a signal indicating H level, the modulation signal i is applied to the second control means 38 based on the mode signal h indicating H level and the modulation signal i whose polarity is inverted. As described above, the gate circuit 51 gives the signal indicating the H level to the second control means 34 in the reproduction mode, and gives the modulation signal i to the second control means 38 in the recording mode.

When the signal from the gate circuit 51 is a signal indicating H level, the second control means 38, based on the signal indicating H level, the second control signal j indicating a constant voltage, that is, a DC voltage. Is given to the calculation means 39. When the signal from the gate circuit 51 is the modulation signal i, the second control means 38 converts the modulation signal i into an amplitude suitable for the pulse power so that information can be recorded on the optical disc. Then, the second control signal j, which is a pulse-shaped signal in which the offset voltage is adjusted, is given to the arithmetic means 39.

As described above, the second control means 38 applies the first drive voltage to the semiconductor laser 32 in the reproducing mode based on the mode signal h from the mode instructing means 35, and the second driving voltage in the recording mode. The drive voltage is controlled so that the semiconductor laser 32 is supplied with the drive voltage, and the second control signal j indicating the drive voltage is supplied to the arithmetic means 39. The value of the drive voltage indicated by the second control signal j is a value having a positive sign, for example.

The mono-multivibrator 40 is triggered by the rising of the mode signal h from the mode command means 35 to change from the signal showing the L level to the signal showing the H level, and becomes the H level only during the predetermined time T. The pulsed opening / closing signal n is given to the switch means 41. In other words, the mono-multivibrator 40 gives the opening / closing signal n indicating the L level to the switch means 41 in the reproducing mode, and when switching from the reproducing mode to the recording mode, the mono multivibrator 40 outputs the opening / closing signal n indicating the H level only for the time T. Switch means 4
1 and the time T elapses, the switching means 41 is supplied with the open / close signal n indicating the L level.

When the opening / closing signal n from the mono multivibrator 40 is a signal indicating the L level, the switch means 41 brings the both ends of the capacitor 41 into the state in which they are not short-circuited, that is, the off state 41a, and the opening / closing signal n is set to the H level. In the case of the signal shown, both ends of the capacitor 41 are short-circuited, that is, the on state 41b is set.

The photodetector 33 detects the quantity b of light emitted from the semiconductor laser 32, and supplies the current-voltage converting means 42 with an output current signal c representing the detected current, which is the detection result. The current-voltage converting means 42 converts the output current signal c into an output voltage signal d indicating the voltage corresponding to the current, and gives the output voltage signal d to the other input terminal of the differential amplifying means 45.

The reference voltage signal e is applied to one input terminal of the differential amplifying means 45, and the output voltage signal d is applied to the other input terminal of the differential amplifying means 45. Differential amplifier 4
5 is the output voltage signal d from the voltage value indicated by the reference voltage signal e.
Subtract the voltage value indicated by. Thereby, the differential amplification means 45
Calculates the difference between the voltage value indicated by the reference voltage signal e and the voltage value indicated by the output voltage signal d, and outputs the deviation signal f indicating the voltage obtained by amplifying the difference as the second resistance element 47 and the capacitor 4.
8 to the low pass filter 53.

The low-pass filter 53 processes the deviation signal f so that it has a frequency equal to or lower than a predetermined frequency in the frequency band of the deviation signal f, and supplies it to the first control means 37 as a noise removal signal g. The noise removal signal g has a low frequency and is a signal indicating a voltage. In the reproduction mode, the capacitor 48 stores an electric charge according to the electrostatic capacitance C.

The low-pass filter 53 is the first control means 3
The control system including 7 is restricted so as not to have an unnecessarily high frequency band, and an unstable driving state, for example, oscillation is prevented. Since the control of the semiconductor laser 32 is a control for suppressing a change in temperature, that is, a time-slow change such as a temperature drift, the frequency band to be controlled is set to be a low frequency band. Is common.

Further, the low-pass filter 53 prevents, for example, pulsed noise having a large amplitude from being applied to the semiconductor laser 32, such as high frequency noise such as surge which is noise that destroys the elements of the electric circuit. Further, when the semiconductor laser 32 emits a pulsed light that emits a light beam so that the waveform indicating the emitted light amount b has a pulse shape, the pulse component included in the output voltage signal d of the current-voltage converter 42 is removed. Thus, unnecessary fluctuations in the output voltage signal d are suppressed.

The first control means 37 includes the low-pass filter 5
Based on the noise-removed signal g from the signal No. 3, gain adjustment and phase compensation are performed, and the first control signal m is given to the arithmetic means 39. The noise removal signal g is the semiconductor laser 3
2 is a signal based on the detection result obtained by detecting the amount b of emitted light from the second light source. The first control means 37 controls the drive voltage applied to the semiconductor laser 32 based on the detection result of the photodetector 33, and the drive voltage The first control signal m indicating
Give to. The value of the drive voltage indicated by the first control signal m is a value having a positive sign, for example.

The operation means 39 current-amplifies the operation control signal k obtained by operation based on the first control signal m from the first control means 37 and the second control signal j from the second control means 38. It is given to the means 34. In this way, the arithmetic means 39 produces the arithmetic control signal k indicating the arithmetic drive voltage based on the respective drive voltages indicated by the first control signal m by the first control means 37 and the second control signal j by the second control means 38. Ask. The arithmetic drive voltage indicated by the arithmetic control signal k is the sum of the voltage value of the drive voltage indicated by the second control signal j and the voltage value of the drive voltage indicated by the first control signal m. In the reproduction mode, the arithmetic drive voltage is controlled so that the voltage value is the same as the voltage of the reproduction mode reference voltage source. In the recording mode, the operation driving voltage is controlled so that the voltage value is the same as the voltage of the second recording mode reference voltage source. The value of the arithmetic drive voltage indicated by the arithmetic control signal k is, for example, the first control signal m and the second control signal m.
When the value of the drive voltage indicated by the control signal j is a positive value, the value has a positive sign.

Based on the operation control signal k from the operation means 39, the current amplification means 34 supplies the semiconductor laser drive current a indicating the current corresponding to the operation drive voltage to the semiconductor laser 32 via the first resistance element 46. Give to. When the operation control signal k is a signal indicating a DC voltage, the semiconductor laser drive current a based on the operation control signal k is the semiconductor laser 32.
Therefore, the semiconductor laser 32 emits a light beam so that the emitted light amount b becomes a constant value, that is, emits direct current. When the arithmetic control signal k is a pulse-shaped signal corresponding to the modulation signal i, the semiconductor laser drive current a based on the arithmetic control signal k is given to the semiconductor laser 32, so that the semiconductor laser 32 emits pulses. In other words, the current amplification means 34 binarizes the given pulse-shaped arithmetic control signal k with a predetermined threshold value, and when the value indicated by the arithmetic control signal k is larger than the threshold value. First, the semiconductor laser 32 emits a light beam, and when it is smaller than the threshold value, the light beam is not emitted.

After the semiconductor laser 32 has been driven in this manner, the photodetector 33 detects the amount of emitted light b, and the drive voltage applied to the semiconductor laser 32 by the first control means 37 is controlled based on the detection result. To do. The drive voltage controlled by the first control means 37 is fed back to the arithmetic means 39 based on the detection result of the photodetector 33. As described above, since the reference voltage signal e and the output voltage signal d are controlled to be equal by the transmission system from the photodetector 33 to the first control means 37, the current amplification means 34 operates in each drive state. A driving voltage can be applied to the semiconductor laser 32 to drive it. Therefore, it is possible to prevent damage and deterioration of the semiconductor laser 32 after controlling so that the emitted light amount b from the semiconductor laser 32 becomes a predetermined command light amount to be emitted.

In the recording mode, the frequency of the modulated signal i is a relatively high frequency of several [MHz] to several tens [MHz], and when the semiconductor laser 32 emits a pulse, the photodetector 33 causes a pulse. The current-voltage converting means 42 is supplied with the output current signal c indicating a smoothed value instead of the above value. As a result, the noise removal signal g becomes a signal indicating a voltage corresponding to the average light amount of the pulsed light.
Therefore, this average light quantity is obtained by the recording mode reference voltage source 44.
The semiconductor laser drive current a given to the semiconductor laser 32 is controlled so as to be the same as the command light amount corresponding to the voltage of.

In the recording mode, the semiconductor laser 3
Since it is necessary to cause a physical change in the recording film of the optical disc by the light beam from the second optical disc,
It is necessary to apply a second drive voltage higher than the drive voltage to the semiconductor laser 32, and when recording by pulse emission, since the light amount is controlled based on the average light amount of the emitted light amount b, the efficiency of light emission by pulse emission is increased. The peak power of the emitted light amount b increases in proportion to the light emission duty indicating. Specifically, in the reproduction mode, the emitted light amount b from the semiconductor laser 32 has a relatively small value of 10 [mW] or less, whereas in the recording mode, it is several tens [mW] to 60 [mW].
An emitted light amount b of [mW] is required.

FIG. 2 is a graph showing an example of the transition of the value indicated by each signal when the semiconductor laser 32 is driven by switching from the reproduction mode to the recording mode. 2 (1) shows the relationship between the mode signal h and time, FIG. 2 (2) shows the relationship between the opening / closing signal n and time, and FIG. 2 (3) shows the operation control signal k and time. 2 (4) shows the relationship between the emitted light amount b and time. When the semiconductor laser 32 is driven in the reproduction mode, the mode command means 35 outputs the mode signal h indicating the L level to the changeover switch 50 and the gate circuit 51.
And the mono multivibrator 40 (FIG. 2).
(See (1)). The changeover switch 50 connects the reproduction mode reference voltage source 43 and one input terminal of the differential amplification means 45. The reproduction mode reference voltage source 43 supplies the differential amplification means 45 with a reference voltage signal e indicating a voltage corresponding to the command light amount in the reproduction mode.

The gate circuit 51 outputs the H signal based on the mode signal h indicating the L level and the modulation signal i whose polarity is inverted.
A signal indicating the level is given to the second control means 38. The second control means 38 gives a second control signal j indicating a DC voltage to the calculating means 39 based on the signal indicating the H level.

The mono-multivibrator 40 gives an opening / closing signal n indicating L level to the switch means 41 based on the mode signal h indicating L level (see FIG. 2 (2)).
The switching means 41 is in the OFF state 41a because the applied opening / closing signal n is a signal indicating the L level.

The differential amplifying means 45 calculates the difference between the voltage values of the reference voltage signal e and the output voltage signal d, and gives the amplified deviation signal f to the low pass filter 53. As described above, the low-pass filter 53 processes the frequency band of the deviation signal f and gives the noise removal signal g to the first control means 37. At this time, the charge corresponding to the electrostatic capacitance C is stored in the capacitor 48.

The first control means 37 carries out processing such as gain adjustment and phase compensation of the noise removal signal g, and gives the first control signal m indicating the drive voltage to the arithmetic means 39. The calculating means 39 gives the current amplifying means 34 an arithmetic control signal k indicating the arithmetic drive voltage obtained by arithmetically operating the first control signal m and the second control signal j indicating the DC voltage.

The current amplifying means 34 converts the operation control signal k into a semiconductor laser drive current a and drives the semiconductor laser 32. In the reproduction mode, the operation control signal k is a signal indicating a DC voltage, and therefore the semiconductor laser 3
2 emits direct current.

When the semiconductor laser 32 is driven, the photodetector 33 detects the amount b of light emitted from the semiconductor laser 32 and gives an output current signal c indicating the detection result to the current / voltage converting means 42. The current-voltage converting means 42 converts the output current signal c into an output voltage signal d and supplies the output voltage signal d to the other input terminal of the differential amplifying means 45. The differential amplifying means 45 operates as described above and causes the low-pass filter 53 to output the deviation signal f.
give.

The deviation signal f is obtained by the low-pass filter 53.
Is processed and the noise removal signal g is given to the first control means 37, the first control means 37 causes the noise removal signal g
Then, the gain adjustment and the phase compensation are processed and given to the arithmetic means 39. The first control means 37 includes the semiconductor laser 3
The drive voltage applied to the semiconductor laser 32 is controlled so that the difference between the voltage values of the reference voltage signal e and the output voltage signal d becomes zero on the basis of the detection result of the emitted light amount b from 2. As described above, in the reproduction mode, the drive voltage controlled by the first control means 37 is fed back to the calculation means 39, and the drive voltage controlled by the second control means 38 is supplied to the calculation means 39. As described above, the calculation drive voltage is obtained in consideration of the detection result of the emitted light amount b from the semiconductor laser 32, and therefore, the voltage of the reproduction mode reference voltage source 43 is controlled to be the same as the voltage value. Therefore, when the semiconductor laser 32 is driven, as shown in FIG. 2 (4), the emission light amount b from the semiconductor laser 32 is the command light amount to be emitted, that is, the voltage of the reproduction mode reference voltage source 43, that is, The light amount Pr corresponds to the first drive voltage.

When the semiconductor laser 32 is driven by switching from the reproduction mode to the recording mode, the mode command means 35
As shown in FIG. 2A, the mode signal h indicating the L level to the H level is applied to the changeover switch 50, the gate circuit 51, and the mono-multivibrator 40. The changeover switch 50 includes the recording mode reference voltage source 43 and the differential amplifying means 4.
5 is connected to one of the input terminals. The recording mode reference voltage source 43 supplies a reference voltage signal e indicating a voltage corresponding to a predetermined command light amount to be emitted in the recording mode to the differential amplifying means 45.

The gate circuit 51 supplies the modulation signal i to the second control means 38 based on the mode signal h indicating the H level and the modulation signal i whose polarity is inverted. Second control means 3
Reference numeral 8 applies a second control signal j, which is based on the modulated signal i, to an amplitude suitable for the pulse power so that the information can be recorded on the optical disc, and further the offset voltage is adjusted to the second control signal j.

The mono-multivibrator 40 is triggered by the rising edge of the mode signal h which changes from the signal showing the L level to the signal showing the H level, and as shown in FIG. A pulsed open / close signal n indicating the level is given to the switch means 41. The time T is set to the minimum time required for the accumulated amount of charge stored in the capacitor 48 to reach zero with respect to the maximum accumulated amount. Specifically, the time T1 is from the time t1 when the ON state 41b is reached to the time t2 when the accumulated amount of electric charge stored in the capacitor becomes zero. The switch means 41 is in the ON state for the time T 4 because the applied opening / closing signal n indicates the H level.
It becomes 1b. At this time, since both ends of the capacitor 48 are short-circuited by the switch means 41, the amount of light stored in the capacitor 48 is the light amount P in the reproduction mode.
The electric charge accumulated by the amount of electric charge according to the voltage when r is emitted is discharged. At this time, the time constant determined by the system from the photodetector 33 to the first control means 37, in particular, the electrostatic capacitance C of the capacitor 48 and the resistance value of the switch means 41 and the time constant for discharging the accumulated charge of the capacitor 48 is set. , The noise removal signal g from the low-pass filter 53 is rapidly reduced by closing the switch means 41, by a time constant determined by the electrostatic capacitance C of the capacitor 48 and the resistance value of the switch means 41 in the ON state 41b. Since it is reduced to zero and shows a value of zero, the semiconductor laser 3 controlled by the first control means 37 is
2 is stopped. The resistance value of the switch means 41 is
If it is set to a very small value of 1 [Ω] or less, the discharge time constant can be set to an extremely small value of several tens [n seconds], so that the period for stopping the driving by the first control means 37 is shortened. You can also

As described above, when the reproduction mode is switched to the recording mode, the semiconductor laser 3 controlled by the first control means 37 is used.
2 is stopped, the voltage value of the operation drive voltage indicated by the operation control signal k has a peak power value of the recording mode reference voltage source 44, that is, the second value, as shown in FIG. It shows a pulse-like waveform in which the bottom power value becomes zero as the voltage value becomes lower than the drive voltage.
When the driving by the control means 37 is restarted, the peak power value and the bottom power value gradually increase, the peak power value becomes the voltage value of the recording mode reference voltage source 44, and the bottom power value becomes the first value. It becomes the voltage value of the drive voltage under the control of the control means 37. Therefore, the semiconductor laser drive current a given from the current amplifying means 34 corresponds to the operation drive voltage indicated by the operation control signal k. Therefore, as shown in FIG. Emitted light amount P to be emitted in the recording mode
Never exceed w.

When the time T elapses after switching from the reproduction mode to the recording mode, the opening / closing signal n from the mono-multivibrator 40 changes from the H level to the L level, so that the switch means 41 is in the off state. 41a. Along with this, the driving of the semiconductor laser 32 by the first control means 37 is restarted. Based on the detection result of the photodetector 33, the first control unit 39 controls the drive voltage applied to the semiconductor laser 32 so that the reference voltage signal e and the output voltage signal d have the same voltage value. As a result, the drive voltage applied to the semiconductor laser 32 is controlled so that the voltage value becomes the same as the voltage of the recording mode reference voltage source 44.

The amount b of light emitted from the semiconductor laser 32 is set to the voltage of the recording mode reference voltage source 44 by taking a response time determined based on the frequency band of the system from the photodetector 33 to the first control means 37. The corresponding emitted light amount Pw is obtained. As a result, as shown in FIG. 2 (4), the light emission amount b from the semiconductor laser 32 in the recording mode is lower than the emission light amount Pw, which is the command light amount to be emitted, from the photodetector 33 to the first control. Even the emission is controlled so as to reach the amount Pw to be emitted, taking a response time determined based on the frequency band of the system reaching the means 37.

As described above, when the reproduction mode is switched to the recording mode, the semiconductor laser 32 is supplied with a voltage equal to or lower than the second drive voltage. As a result, it is possible to prevent a voltage higher than the second drive voltage from being applied to the semiconductor laser 32, so that damage and deterioration of the semiconductor laser 32 can be prevented. In this way, when the reproduction mode is switched to the recording mode, the amount b of light emitted from the semiconductor laser 32 is forcibly limited to prevent damage and deterioration of the semiconductor laser 32.

In the light emitting element control device 31, an opening / closing signal n indicating the H level from the mono multivibrator 40.
However, since the time T given to the switch means 41 is set to a time sufficient to discharge the electric charge stored in the capacitor 48, damage and deterioration of the semiconductor laser 32 can be reliably prevented.

When the reproduction mode is switched to the recording mode, the mono-multivibrator 40 causes the photodetector 33 to operate.
To decrease the time constant of the system from the first control means 37,
In other words, the mono-multivibrator 40 makes the time T shorter than the time at which all the charges stored in the capacitor 48 are discharged, so that the amount b of light emitted from the semiconductor laser 32 becomes the voltage of the recording mode reference voltage source 44. It is possible to shorten the time until it becomes equal to the corresponding emitted light amount Pw.

The time T during which the switch means 41 short-circuits both ends of the capacitor 48 is the time when the charge accumulated in the capacitor 48 is the maximum amount of charge, the recording mode reference voltage source 4
The voltage applied from No. 4 is reduced to the amount of accumulated charge as given to the first control means 37, and is determined as the time until it becomes appropriate charge. As a result, the discharge of the charge from the capacitor 48 is stopped midway, and the driving by the first control means 37 is restarted at the same time as the time required to discharge all the charges stored in the capacitor 48, and at the same time the calculation drive voltage is reached. Can be set to a voltage corresponding to the amount Pr of light emitted from the semiconductor laser 32.

In the light-emitting element control device 31, when the reproduction mode is switched to the recording mode, the switch means keeps the ON state 41b until the electric charge stored in the capacitor 48 becomes zero. Therefore, the mono-multivibrator 40 is used. Even if the opening / closing signal n from the signal is switched from the signal showing the H level to the signal showing the L level, and the driving of the semiconductor laser 32 by the first control means 37 is restarted, the emission light amount b from the semiconductor laser 32 is An extra period is required by the response time determined by the frequency band of the transmission system from the photodetector 33 to the first control means 37 until the amount of emitted light Pw corresponding to the two drive voltages is reached. On the other hand, the first
At the same time that the driving of the semiconductor laser 32 by the control means 37 is restarted, the mono-multivibrator 40 is opened / closed so that the emitted light amount b from the semiconductor laser 32 becomes equal to the emitted light amount Pw corresponding to the second drive voltage. Signal n is H
A time T which is a signal indicating the level is determined.

FIG. 3 is a graph showing an example of the transition of the value indicated by each signal when the semiconductor laser 32 is driven by switching the reproduction mode to the recording mode by changing the time T.
FIG. 3 (1) shows the relationship between the mode signal h and time, and FIG. 3 (2) shows the relationship between the opening / closing signal n and time.
(3) shows the relationship between the operation control signal k and time, and FIG.
(4) shows the relationship between the emitted light amount b and time. After the time T has passed, the semiconductor laser 3 by the first control means 37
At the same time when the driving by 2 is restarted, the semiconductor laser 32
As shown in FIG. 3 (4), the amount b of emitted light from is the same as the amount of emitted light Pw corresponding to the voltage of the recording mode reference voltage source 44, that is, the second drive voltage. As a result, when the reproduction mode is switched to the recording mode, the semiconductor laser 3
2 is not applied with a driving voltage higher than the second driving voltage, and the driving by the first control means 37 is started in a short time, and the second driving voltage in the second state is set to the semiconductor laser 3
Can be given to 2.

As an effect of the present invention, even if the driving of the semiconductor laser 32 by the first control means 37 is stopped, it can be driven by the second control means 38, and as a result, the driving of the semiconductor laser 32 is stopped. Never. Further, since the voltage higher than the second drive voltage is not applied, the semiconductor laser 32 is not damaged or deteriorated. Thus, it is possible to continuously drive the semiconductor laser 32 and prevent damage and deterioration of the semiconductor laser 32.

The above-described embodiment is merely an example of the present invention, and the configuration can be changed within the scope of the present invention. In the above-described embodiment, when the semiconductor laser 32 is switched from being driven by the first drive voltage to being driven by the second drive voltage higher than the first drive voltage, a voltage higher than the second drive voltage is applied to the semiconductor laser 32. Although the point of controlling not to apply is described, the effect of the present invention can be similarly obtained when switching from driving with the second driving voltage to driving with the first driving voltage lower than the second driving voltage.

A high-speed laser drive circuit for driving the semiconductor laser 32 at high speed (see Japanese Patent Application No. 2000-212356).
By incorporating the light emitting element control device 31 in the above, it is possible to prevent damage and deterioration of the semiconductor laser 32 while allowing the semiconductor laser 32 to emit high-speed pulse light.

In the light emitting element control device 31, the semiconductor laser drive current a is set to several hundred [MH] in the recording mode.
z] is applied to perform high frequency superimposition processing,
Although the noise due to the return light of the semiconductor laser 12 is suppressed, the high-frequency superposition processing is performed at a frequency much higher than the frequency band for controlling the emitted light quantity of the semiconductor laser 12, and therefore is not a target of light-emitting element control. Of course, the semiconductor laser 12 is described as being driven by applying a voltage such that a constant current flows.

In the light emitting element control device 31, the time T during which the opening / closing signal n indicating the H level is applied is the capacitor 4
It is set to a period sufficient to discharge the charge stored in No. 8, but it is required to discharge the charge, that is, the time required to discharge the charge and the period to store the charge, that is, to store the charge. The sum of time is several [μsec] ~
Since it is about several tens of microseconds, even if the emitted light amount b from the semiconductor laser 32 becomes zero, it does not adversely affect the focus servo and tracking servo of the optical recording / reproducing apparatus 30.

As the light emitting element, in addition to the semiconductor laser 32,
For example, a light emitting diode may be used. The low-pass filter 53 processes the drive voltage applied to the semiconductor laser 32 so as to have a frequency in the low frequency band, but the drive voltage having this low frequency may include a DC voltage.

The drive voltage under the control of the second control means 38 may be equal to or lower than the drive voltage under the control of the first control means 37. As a result, the second drive voltage is applied to the semiconductor laser 32, and the damage and deterioration of the semiconductor laser 32 can be prevented more reliably.

Since the driving voltage applied to the semiconductor laser 32 can be suppressed to a low level immediately after the driving mode of the semiconductor laser 32 is switched from the reproduction mode, which is the first state, to the recording mode, which is the second state, A voltage higher than the two driving voltage is prevented from being applied to the semiconductor laser 32, the semiconductor laser 32 is driven by the current amplifying means 34 so as not to be damaged, and the emitted light quantity b corresponds to the command light quantity as much as possible. The semiconductor laser 32 can be driven by applying a drive voltage to be applied according to the drive state. Therefore, it is possible to drive the semiconductor laser 32 so that a large amount of light required for each driving state can be emitted while preventing a large load from being applied to the semiconductor laser 32.

Even when the driving state of the semiconductor laser 32 is switched from the reproducing mode to the recording mode, it is possible to perform the switching within a short period of time.
Since it is possible to drive the semiconductor laser 32 by applying the second drive voltage in the recording mode, the semiconductor laser 32 can be quickly emitted in the recording mode with the required amount of light. It can be driven without damaging 32.

While the driving of the semiconductor laser 32 based on the control of the first control means 37 is stopped, the semiconductor laser 3 is
Since the drive voltage applied to 2 is equal to or lower than the second drive voltage, the current amplification means 34 surely prevents the semiconductor laser 32 from being damaged without applying a high voltage to the semiconductor laser 32. Can be driven.

When the drive by the first control means 37 is restarted, the drive voltage by the first control means 37 is zero and changes as necessary, so that the current amplifying means 34 is higher than the second drive voltage. It is possible to prevent the semiconductor laser 32 from being damaged without applying a voltage to the semiconductor laser 32, and drive the semiconductor laser 32 so that the emitted light amount b corresponds to the command light amount in each driving state.

Immediately after the driving state of the semiconductor laser 32 is switched from the reproducing mode to the recording mode, the operation driving voltage applied to the semiconductor laser 32 can be suppressed to a low level, so that the current amplifying means 34 is higher than the second driving voltage. Without applying a high voltage to the semiconductor laser 32, the semiconductor laser 32 can be driven so as not to be damaged, and an operation drive voltage can be applied to the semiconductor laser 32 so that the emitted light quantity b corresponds to the command light quantity. Therefore, the semiconductor laser 32 can be driven by applying a driving voltage to be applied to the semiconductor laser 32 according to the driving state, and the semiconductor laser 32 can be prevented from being damaged.
Optical recording / reproducing apparatus 30 capable of recording and reproducing
The durability of can be increased.

[0085]

According to the present invention, the operation drive voltage applied to the light emitting element can be suppressed to a low level immediately after the drive state of the light emitting element is switched from the first state to the second state, so that the second drive voltage can be reduced. A predetermined drive voltage according to the driving state, which prevents the light emitting element from being applied with a voltage higher than that of the light emitting element, drives the light emitting element so as not to be damaged by the driving means, and causes the emitted light amount to correspond to the command light amount as much as possible. Can be given to the light emitting element to drive. Therefore, it is possible to drive the light emitting element so that a large amount of light required for each driving state can be emitted while preventing a large load from being applied to the light emitting element.

Further, according to the present invention, even if the driving state of the light emitting element is switched from the first state to the second state, the second driving voltage in the second state is applied to the light emitting element for driving within a short period after switching. Therefore, in the second state, the light amount required for the light emitting element can be emitted at an early stage, and the light emitting element can be driven without being damaged.

According to the present invention, the driving voltage applied to the light emitting element is equal to or lower than the second driving voltage while the driving of the light emitting element based on the control of the first control means is stopped. It is possible to reliably prevent the light emitting element from being damaged and drive the light emitting element without applying a high voltage to the light emitting element.

Further, according to the present invention, when the drive by the first control means is restarted, the drive voltage by the first control means is zero and changes as necessary, so that the drive means is operated by the second drive voltage. It is possible to prevent the light emitting element from being damaged without applying a higher voltage to the light emitting element, and to drive the light emitting element so that the emitted light amount corresponds to the command light amount in each driving state.

Further, according to the present invention, immediately after the driving state of the light emitting element is switched from the first state to the second state, the operation driving voltage applied to the light emitting element can be suppressed to a low level. It is possible to drive the light emitting element by applying an arithmetic drive voltage so that the light emitting element is driven without damaging the light emitting element with a voltage higher than the two drive voltage, and the emitted light quantity corresponds to the command light quantity. Therefore, it is possible to prevent damage to the light emitting element and perform recording and reproduction while giving a predetermined drive voltage to the light emitting element according to the driving state so that the light emitting element can be driven. can do.

[Brief description of drawings]

FIG. 1 is a light emitting element control device 31 according to an embodiment of the present invention.
3 is a block diagram showing the electrical configuration of FIG.

FIG. 2 is a graph showing an example of transition of values indicated by each signal when the semiconductor laser 32 is driven by switching from the reproduction mode to the recording mode. 2 (1) shows the relationship between the mode signal h and time, FIG. 2 (2) shows the relationship between the opening / closing signal n and time, and FIG. 2 (3) shows the operation control signal k and time. 2 (4) shows the relationship between the emitted light amount b and time.

FIG. 3 is a graph showing an example of changes in the value indicated by each signal when the semiconductor laser 32 is driven by switching the reproduction mode to the recording mode by changing the time T. Figure 3 (1)
Shows the relationship between the mode signal h and time, and is shown in FIG.
Indicates the relationship between the opening / closing signal n and time, and FIG.
The relationship between the operation control signal k and time is shown in FIG.
The relationship between the emitted light amount b and time is shown.

FIG. 4 is a block diagram showing an electrical configuration of a conventional light emitting element control device 1.

FIG. 5 is a graph showing an example of transition of values indicated by each signal when the semiconductor laser device 3 is driven by switching from the reproduction mode to the recording mode in the light emitting device control device 1. 5 (1) shows the relationship between the mode signal h and the time, FIG. 5 (2) shows the relationship between the operation control signal k and the time, and FIG. 5 (3) shows the emitted light amount b and the time. Shows the relationship.

[Explanation of symbols]

30 Optical recording / reproducing apparatus 31 Light emitting element control device 32 Semiconductor laser 33 Photodetector 34 Current amplification means 37 First Control Means 38 Second control means 39 computing means 40 Mono multivibrator 41 switch means 49 switching means

Continued front page    F term (reference) 5D090 AA01 BB03 BB04 CC06 DD03                       EE01 HH01 KK03                 5D119 AA23 AA33 BA01 FA05 HA12                       HA46 HA68                 5D789 AA23 AA33 BA01 FA05 HA12                       HA46 HA68                 5F073 BA05 EA28 GA12 GA20 GA24                       GA38

Claims (5)

[Claims] 1. A light emitting element is driven by switching at least a first state of driving with a first driving voltage set in advance and a second state of driving with a second driving voltage higher than the first driving voltage. A light emitting element control device, comprising: detection means for detecting the amount of light emitted from the light emitting element; first control means for controlling a drive voltage applied to the light emitting element based on the detection result of the detection means; and emission from the light emitting element. A second control for controlling the drive voltage applied to the light emitting element so as to apply the first drive voltage when in the first state and the second drive voltage when in the second state, based on the command light amount that commands the light amount Means, and the respective drive voltages by the first and second control means,
An arithmetic means for obtaining an arithmetic drive voltage applied to the light emitting element, a drive means for applying the arithmetic drive voltage by the arithmetic means to the light emitting element to drive it, and a switch for switching the drive state of the light emitting element between the first state and the second state. And the driving state of the light emitting element is switched from the first state to the second state, the driving of the light emitting element based on the control of the first control means is temporarily stopped, and then the driving based on the control of the first control means is restarted. A light emitting element control device comprising a third control means. 2. The third control means reduces the time constant of the transfer function in the transfer system from the detection means to the first control means while the driving of the light emitting element based on the control of the first control means is stopped. The light emitting element control device according to claim 1, wherein 3. The driving voltage applied to the light emitting element is substantially the same as or less than the second driving voltage during the period in which the driving of the light emitting element based on the control of the first control means is stopped. The light emitting element control device according to claim 1 or 2. 4. A switch means for reducing the drive voltage applied to the light emitting element to zero under the control of the first control means while the driving of the light emitting element under the control of the first control means is stopped. The light emitting element control device according to claim 1, wherein 5. A second state in which a light emitting element is driven in a first state in which a predetermined first driving voltage is applied to reproduce information from a recording medium, and a second driving voltage in which the light emitting element is higher than the first driving voltage is applied. An optical recording / reproducing apparatus for driving information in a recording medium to record information on a recording medium, wherein a detection means for detecting the amount of light emitted from the light emitting element, and a drive voltage applied to the light emitting element based on the detection result of the detection means. Based on each drive voltage by the first and second control means, the first control means for controlling the drive voltage applied to the light emitting element based on the command light quantity for instructing the light emission quantity from the light emitting element hand,
An arithmetic means for obtaining an arithmetic drive voltage applied to the light emitting element, a drive means for applying the arithmetic drive voltage by the arithmetic means to the light emitting element to drive it, and a switch for switching the drive state of the light emitting element between the first state and the second state. And the driving state of the light emitting element is switched from the first state to the second state, the driving of the light emitting element based on the control of the first control means is temporarily stopped, and then the driving based on the control of the first control means is restarted. An optical recording / reproducing apparatus comprising: a third control means.