JPS63234419A - Output controller for semiconductor laser - Google Patents

Abstract

PURPOSE:To extent the life of a semiconductor laser itself by modulating a current including a reproducing current by a modulating circuit at the time of recording to produce the state where the synthesized current does not flow to the semiconductor laser at all at the time of turning-off. CONSTITUTION:At the time of recording, the current where the reproducing current flowing to always keep a stable reproducing level and a recording current having a preliminarily set value are synthesized flows to a semiconductor 25 through a modulating circuit 34 even if the quantity of light of the semiconductor laser is changed by an influence of disturbance due to the variance of temperature. Consequently, the recording level is not varied and is always kept in a stable value. At this time of recording, the state where the current does not flow to the semiconductor laser 25 at all exists at the time of turning- off because the synthesized current flowing to the semiconductor laser 25 is modulated. Thus, life of the semiconductor laser 25 is extended.

Description

[Detailed description of the invention] Technical field The present invention reproduces information using a semiconductor laser.

The present invention relates to an output control device in an optical storage device such as a magneto-optical disk that performs recording and erasing.

Prior Art A conventional output control device using a semiconductor laser is disclosed in Japanese Patent Laid-Open No. 58-158051. That is, as shown in FIGS. 10 and 11, the semiconductor laser 3 of the optical head 2 provided close to the optical disk 1
The output signal from is amplified by amplifier 4 and output signal a
The difference between this output signal a and the reference signal S is amplified by the error amplifier 5, and furthermore, the output signal is temporarily held by the sample and hold circuit 6, and is put into the sample state or the hold state depending on the state of the control signal C. becomes.

When reproducing information, the control signal C becomes a logic "1" level and becomes a sample state, and the output signal from the sample hold circuit 6 and the beam modulation signal d (usually O
v) by an adder 7, and sends the addition result (in this case, only the output signal of the sample and hold circuit 6) to a current supply circuit 8, which receives the input output of the adder 7. Semiconductor laser 3 generates a drive current according to the signal.
supply to.

On the other hand, when recording information, control signal C is set to logic # for that period.
By setting it to OIT level, it becomes a hold state,
The immediately preceding output signal of the error amplifier 5 is stored and held, and the output signal from the sample and hold circuit 6 and the beam modulation signal d are stored.
(recording pulses with a pulse width of several hundred ns or less) are added by an adder 7, and the addition result is sent to a current supply circuit 8, which supplies a drive current according to the amplitude of the beam modulation signal d. is supplied to the semiconductor laser only during the period of the signal d.

In this way, the output level during recording is determined by superimposing the beam modulation signal d during recording on the output level during playback, so the average output during recording increases, and when the recording pulse is off, The voltage has not been completely lowered to OV, and as a result, the life of the semiconductor laser 3 may be shortened.

Purpose The present invention aims to provide an output control device for a semiconductor laser in an optical storage device, which is capable of individually producing stable and optimal outputs for reproduction, recording, and erasing, and also extending the life of the semiconductor laser. purpose.

Structure The present invention comprises a semiconductor laser, a detector that detects light emitted from the semiconductor laser, a sample hold circuit that temporarily stores the output of the detector, and an output of the sample hold circuit and a reference voltage. a comparator for comparing, a reproduction current source for supplying a reproduction current for reproduction, a recording/erasing current source for supplying a recording current for recording and an erasing current for erasing; It consists of a current control means for controlling the current of this current source for recording and erasing, and a modulation circuit that modulates the combined current of the current from the current source for reproduction and the current from the current control means. Even if the light intensity of the semiconductor laser changes due to the influence of changes, etc., the reproduction current that flows and the recording current (or erasing current) of a preset value are set so that a stable reproduction level is always maintained. Since the combined current flows through this semiconductor laser, it is possible to always output a stable output during recording and erasing.Also, during recording, the modulation circuit modulates the reproduction current as well, so when the semiconductor laser is off, there is no output at all. There is a state in which no current flows, and this makes it possible to extend the life of the semiconductor laser.

Furthermore, by forming the current control means with independent recording current control means and erasing current control means, the current values for reproduction, recording, and erasing can be adjusted separately.

Stable and optimal output can be produced separately during recording and erasing. ``First, the structure and operation of an optical storage device (here, a magneto-optical disk is taken as an example) will be explained based on FIG. 9.

In the optical recording device 9, during reproduction, a laser beam whose light amount is controlled from the semiconductor laser 11 is emitted by the reproduction output of the output control device 10. This laser beam is made into a parallel beam by a collimator lens 12, reflected by a beam splitter 13, focused by an objective lens 14, and reflected by a disk 15 surface. Thereafter, this reflected light flux passes through the beam splitter 13 and is divided into two light fluxes, a transmitted light flux and a reflected light flux, by the beam splitter 16.

The light beam transmitted through this beam splitter 16 is transmitted through the lens 1
7 and is further divided into two beams, a transmitted beam and a reflected beam, by a half mirror 18, and the transmitted beam enters a tracking servo detector 19 for a predetermined control output, and the other reflected beam passes through the lens 20, enters the focus servo detector 21, and performs a predetermined control output.Meanwhile, the light flux reflected by the beam splitter 16 passes through the lens 22, enters the magneto-optical signal detector 23, and is in a reproducible state. Become.

Further, during recording, a laser beam whose light amount is controlled is emitted from the semiconductor laser 11 according to the recording output of the output control device 10. This laser beam is focused on the optical recording medium on the surface of the disk 15 using the same principle as in the above-mentioned reproduction, and then recorded by the magnetic field generated by the electromagnet 24. Furthermore, erasing is performed in substantially the same manner as recording, but in this case no signal is generated due to recording pulses.

Next, a first embodiment of the present invention will be explained based on FIGS. 1 to 3.

First, a semiconductor laser 25 as a light source and a detector 26 that detects light emitted from the semiconductor laser 25 are connected. An amplifier 2 that amplifies the output of this detector 26
7, a sample and hold circuit 28 that temporarily stores the output from this amplifier, and this sample and hold circuit 28
and a comparator 29 that compares the output of the reference voltage v6 with the reference voltage v6 are successively connected in series.

The output from the comparator 29 is connected to the input side P of a regeneration current source 30 that supplies a regeneration current for regeneration. The output side Q of this reproduction current source 30 is connected in parallel with the output side S of a recording/erasing current source 31 through which a recording current for recording and an erasing current for erasing flow.

The recording and erasing current source 31Φ input side T includes a voltage source 32 that generates a reference voltage for flowing a recording current and an erasing current, and a voltage that flows from this voltage source 32 to the recording and erasing current source 31. A switch element 33 that controls current using a control signal is connected thereto. Note that the voltage source 32. The switch element 33 constitutes a current control means. Further, on the output sides Q and S of the reproducing current source 30 and the recording/erasing current source 31 connected in parallel.

A modulation circuit 34 that modulates the semiconductor laser 25 with a modulation signal during recording is connected.

In such a configuration, first, in order to emit the reproduction level at the time of reproduction, the detector 26 measures the amount of light emitted from the semiconductor laser 25 in a direction not used for reproduction, recording, or erasing. To detect. This amount of light is amplified by an amplifier 27, and since the sample and hold circuit 28 is in a sample state during this reproduction, this amplified amount of light is sent to a comparator 29 as is.

At this time, the amount of light is compared with the reference voltage v0 by the comparator 29, and if this amount of light is lower than the reference voltage v0, more current flows to the reproduction current source 30, and if this scene is higher than the reference voltage v0, the reproduction It serves to reduce the current flowing through the current source 30, and in this way the desired reproduction level can be maintained. Note that during this reproduction, the recording current and erasing current are not flowing, and the modulation circuit 34
is not modulated.

Next, when reading the ID signal (address information), the sample and hold circuit 28 is put into a sample state, and a current having the same output level as during the above-mentioned reproduction is caused to flow through the reproduction current source 30. In this way, by using the reading time of this ID signal to resample the reproduction level and supply a current with the same output level as during reproduction to the reproduction current source 30,
Even if the semiconductor laser 25 is affected by temperature changes, etc., a stable reproduction level can always be maintained, and furthermore, a stable output level can always be supplied during recording and erasing, which will be described later.

Next, in order to emit the recording level at the time of recording, the sample and hold circuit 28 is put into a hold state and the above-mentioned ID
Since a stable reproduction level resampled using the signal reading time is maintained, the reproduction current continues to flow through the reproduction current source 30 so as to maintain a stable reproduction level at all times. On the other hand, the recording/erasing current source 31
For this purpose, a preset optimum recording current is applied by the voltage source 32.

Therefore, during this recording, even if the light intensity of the semiconductor laser changes due to disturbances such as temperature changes, the reproduction current flows and the preset value is recorded so that a stable reproduction level is always maintained. The combined current with the operating current passes through the modulation circuit 34 to the semiconductor laser 2.
As a result, the recording level can always maintain a stable value without fluctuation.

Furthermore, at the time of recording, the combined current flowing through the semiconductor laser 25 is modulated, so there is a state in which no current flows through the semiconductor laser 25 at all during this off time, which also extends the life of the semiconductor laser 25. can.

Next, in order to emit the erase level at the time of erasing, the sample and hold circuit 28 is put into a hold state, and the reproduction current source 30 continues to flow the reproduction current so that a stable reproduction level is always maintained. , is performed in the same manner as in the case of recording described above. On the other hand, a preset optimal erasing current (in this embodiment, since the same voltage source 32 as used during recording is used, a current of the same magnitude as the recording current flows through the recording erasing current source 31). ).

Therefore, during erasing, even if the light intensity of the semiconductor laser changes due to disturbances such as temperature changes, the reproduction current flows and the preset value is erased so that a stable reproduction level is always maintained. The combined current with the operating current passes through the modulation circuit 34 to the semiconductor laser 2.
As a result, the erase level (in this embodiment, the output level is the same as the recording level) can always maintain a stable value without fluctuation.

Next, a second embodiment of the present invention will be described based on FIGS. 4 and 5. Here, the operation of configuration 2 of the recording and erasing parts that is different from the first embodiment will be explained, and the explanation of the operation of configuration 9 of the other same parts will be omitted.

First, regarding the configuration of the portion that performs recording and erasing, a switch element 33 is connected to the input side T of a recording and erasing current source 31 that flows a recording current and an erasing current. A recording voltage source 35 serving as a reference for passing a recording current and an erasing voltage source 36 serving as a reference for passing an erasing current are connected in parallel to this switch element 33 . It is now possible to Note that the switch element 33. The recording voltage source 35. The erasing voltage source 36 constitutes current control means. The configuration of other parts is the same as that of the first embodiment, so a description thereof will be omitted.

In such a configuration, the reproduction level during reproduction remains the same since the reproduction current flowing through the reproduction current source 30 is the same as in the first embodiment.

The recording level during recording is a combination of the above-mentioned reproduction current and the recording current flowing through the recording/erasing current source 31, so for the same reason as the first embodiment, the recording level does not fluctuate and is always stable. The value can be maintained. In this case, the reproducing current does not change, but the recording current can be changed by the preset value of the recording voltage source 35. As a result, the recording level can be adjusted using this recording voltage source 35. can be used to adjust its output level.

Next, since the erasing level during erasing is a combination of the above-mentioned reproduction current and the erasing current flowing through the recording and erasing amount flow source 31, the erasing level does not change for the same reason as in the first embodiment. It can always maintain a stable value.

In this case, the reproduction current does not change, but the erasing current can be changed depending on the value of the erasing voltage source 36 set in advance. can be used to adjust its output level.

As described above, in the first embodiment, since the voltage source 32 serving as the reference for flowing the recording current and the erasing current is the same, the recording level and the erasing level are at the same level. On the other hand, in this second embodiment, a recording voltage source 35 serving as a reference for passing a recording current and an erasing voltage source 36 serving as a reference for passing an erasing current are provided separately. Therefore, the recording level and the erasing level can be adjusted to separate optimal output levels.

Next, a third embodiment of the present invention will be described based on FIGS. 5 and 6. Here, the configuration of the recording and erasing parts is different from the first and second embodiments.

Explains the action and the structure of other similar parts.

A description of the effect will be omitted.

First, the configuration of the part that performs recording and erasing is such that the output side V of the recording current source 37 through which the recording current flows and the output side X of the erasing current source 38 through which the erasing current flows are parallel to the switch cable 33. connected and can be switched by a control signal. This switch element 33 is connected in parallel to the output side Q of the reproducing current source 30. In addition, the recording current source 3
A recording voltage source 35 that serves as a reference for passing a recording current is connected to the input side W of 7, and an erasing voltage source 35 that serves as a reference for passing an erasing current is connected to the input side Y of the erasing current source 38. A source 36 is connected.

In such a configuration, the reproduction level during reproduction does not change because the reproduction current flowing through the reproduction current @30 is the same as in the first and second embodiments.

Since the recording level during recording is a combination of the above-mentioned reproduction current and the recording current flowing through the recording current source 37, the recording level must always be kept at a stable value for the same reason as in the first embodiment. Can be done. In this case, the reproducing current does not change and the recording current can also be changed by the recording voltage source 35 as in the second embodiment. can be used to adjust its output level.

Next, the erase level at the time of erasing is a combination of the above-mentioned reproduction current and the erase current flowing through the erase current source 38, so for the same reason as in the first embodiment, the erase level is always A stable value can be maintained. In this case, the reproduction current does not change and the erasing current can also be changed by the erasing voltage source 36 as in the second embodiment. can be used to adjust its output level.

As described above, in the first and second embodiments, both the recording current and the erasing current flow through the recording/erasing current source 31, whereas in the third embodiment, the recording current flows through the recording current source 31. A recording current source 37 and an erasing current source 38 for supplying an erasing current are provided separately, and a recording voltage source 35 that serves as a reference for supplying a recording current as in the second embodiment is provided. Since the erasing voltage source 36, which serves as a reference for passing the erasing current, is provided separately, the recording level and the erasing level can be adjusted to separate optimal output levels. Therefore, a particularly accurate amount of light and magnetic field are required during recording and erasing, and accurate recording cannot be achieved if the amount of light is too strong or too weak. Considering that it is better to use it for recording purposes, as in this third embodiment.

Current source 37.38 and voltage source 35.3 for erasing and each separately
6, recording and erasing can be performed with higher accuracy.

Next, as another embodiment, a current source 3 for recording and erasing will be described.
By providing switch elements 33 as shown in FIG. 7 on the input sides T, W, and Y of 1.37.38, the voltage source 35
．． 36, the current changes according to the voltage set in advance.

A D/A converter 3 as a switch element as shown in FIG.
3 to change the set voltage.

Effects The present invention thus provides a semiconductor laser, a detector for detecting light emitted from the semiconductor laser, a sample-and-hold circuit for temporarily storing the output of this detector, and an output of this sample-and-hold circuit. and a reference voltage, a reproducing current source that supplies a reproducing current for reproducing, and a recording erasing current source that supplies a recording current for recording and an erasing current for erasing. A current source, a current control means for controlling the current of the recording/erasing current source, and a modulation circuit for modulating a combined current of the current from the reproduction current source and the current from the current control means. Therefore, even if the light intensity of the semiconductor laser changes due to disturbances such as temperature changes, the playback current that flows and the recording current (of a preset value) so that a stable playback level is always maintained. Since a combined current (or erasing current) flows through this semiconductor laser, the reproduction level and storage level are always stable during recording and erasing.

The erase level can be maintained, and since the modulation circuit modulates the reproduction current during recording, there is a state in which the combined current that flows through the semiconductor laser does not flow at all when it is off. Furthermore, by forming the current control means with independent recording current control means and erasing current control means, the current values for reproduction, recording, and erasing can be controlled separately. Ws? ! This makes it very effective especially during recording where an accurate amount of light is required.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing the first embodiment, Figure 2 is a waveform diagram showing its operating state, Figure 3 is an explanatory diagram of the operation of Figure 1, and Figure 4 is a diagram showing the operation of Figure 1.
The figure is a circuit diagram showing the second embodiment, Fig. 5 is a waveform diagram of the second and third embodiments, Fig. 6 is a circuit diagram showing the third embodiment, and Figs. 7 and 8 are FIG. 9 is a side view of an optical storage device, FIG. 10 is a block diagram of a conventional example, and FIG. 11 is a waveform diagram thereof. 25... Semiconductor laser, 26... Detector, 28...
・Sample hold circuit, 29... Comparator, 30...
・Reproduction current source, 34... Modulation circuit, 31, 37.3
8... Current source for recording and erasing, 32, 33, 35. 36.
・Current control means

Claims (1)

[Claims] 1. An output control device for an optical storage device that performs reproduction, recording, and erasing on a recording medium depending on the intensity of the amount of light emitted from a semiconductor laser, which includes: a semiconductor laser; A detector that detects light, a sample hold circuit that temporarily stores the output of this detector,
A comparator that compares the output of this sample and hold circuit with a reference voltage, a reproduction current source that supplies a reproduction current for reproduction, a recording current for recording, and an erasing current for erasing. a current source for recording and erasing that flows through the current source, a current control means for controlling the current of the current source for recording and erasing, and a current that is a composite of the current from the current source for reproduction and the current from the current control means, which is modulated. What is claimed is: 1. A semiconductor laser output control device comprising a modulation circuit. 2. The output control device for a semiconductor laser according to claim 1, wherein the current control means is formed by independent recording current control means and erasing current control means.