JPH0266884A - Control device for luminous energy of light emitting substance - Google Patents

Abstract

PURPOSE:To prevent destruction of a light emitting body under control and eliminate dispersion of a photo-sensor by putting a feedback loop in open state by a changeover means, adjusting the output of the photo-sensor by an adjusting means, closing the feedback loop, and controlling the light amount from the light emitting body. CONSTITUTION:A feedback loop is opened after initial setting, and an LED 25 is allowed to make light emission with the initially set LED current value, and the gain of an I-V converter 31 is adjusted so that the light reception mount signal of a light amount monitoring photo-transistor 61 at this time becomes the same level as the reference voltage, and thus destruction due to large current at the time of light amount control is prevented even though deterioration has arisen in the LED 25. Also dispersions in the light emitting efficiency of the LED 25 and the photo-electric conversion efficiency of the transistor 61 are absorbed by putting the light reception amount signal at the same level as the reference voltage, and light emission from the LED 25 is sensed by a photo-sensor 60 to make light amount control; so that eventual attachment of dust to an external scale 40, slit 50, etc., allows the scale signal to remain constant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a light amount control device for a light emitter used in an optical information recording/reproducing device or the like.

[Prior Art 1] In recent years, optical information recording and reproducing devices that record and reproduce information using light beams have attracted attention.

The optical information recording/reproducing device records information.

A laser diode that emits a light beam for reproduction, and an LE that emits light used to detect the position of an optical head.
A light emitter such as D is used. Said laser da, iA-
Since the light emitting output of the D and L [E D fluctuates due to changes in ambient humidity, etc., a means to stabilize the emitted light a is installed (
Sometimes it happens. For example, Japanese Patent Application Laid-open No. 63-27073 discloses that the amount of light emitted from the forward light and back light of a light emitter (LED) is detected by a light receiver such as a PD ()A1 to a diode). The output of the device is compared with a reference voltage, and as a result of this comparison, the error from the reference value is input to the LED drive circuit to correct the error.

[Problems to be Solved by the Invention] However, if the output of the comparator is directly input to the sweetfish circuit and light HL control is performed as in the conventional example, the LED
If the PD has deteriorated, when a certain current is applied to the LFD to cause it to emit light, the amount of light received by the PD will be much smaller than the desired amount of light. In this case, current is further controlled to flow through the IED in order to compensate for the insufficient amount of light and reach the desired amount of light. At this time, since a large current flows through the LED, there is a possibility that a current exceeding the specifications of the LED flows, leading to destruction of the LED.

In addition, there are variations in the luminous efficiency of light emitters such as LEDs and the photoelectric conversion efficiency of photodetectors such as PDs and phytotransistors, but conventionally, the drive current of the light emitter changes due to this variation. This may lead to the destruction of the light emitter.

The present invention has been made in view of the above circumstances, and can prevent destruction of the light emitting body when controlling the amount of light, and
It is an object of the present invention to provide a light amount control device for a light emitter that can absorb variations in the light emitter and photodetector.

[Means for Solving the Problems] A light amount control device for a light emitting body of the present invention includes a light emitting body that converts electricity into light and emits light, a driving means for driving the light emitting body, and a light emitting body that emits light from the light emitting body. a photodetector for detecting the light, a feedback loop for feeding back a signal based on the output of the photodetector to the driving means in order to control the amount of light from the light emitter 6a; a switching means capable of switching whether or not to substantially send the output from the detector to the drive means side; and a switching means provided between the switching means and the photodetector, the switching means being capable of switching the output of the photodetector to the driving means side; and an adjustable adjustment means.

[Function] The present invention provides switching means 1. = Therefore, the output from the photodetector is not sent to the first stage drive side, and the feedback loop is open. Closes the feedback loop and controls the light amount of the light emitter.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

Figures 1 to 6 relate to the first embodiment of the present invention.
Figure 2 is an explanatory diagram showing the configuration of the light amount control device, Figure 2 is an explanatory diagram showing the arrangement of the photodetector, Figure 3 is a block diagram showing the configuration of a circuit for controlling two positions of gear ridge movement, and Figure 4 is an explanatory diagram showing the configuration of the light amount control device. is a sectional view of the optical disk device, FIG. 5 is a circuit diagram showing a modification of the switching means in J3 in the first embodiment, and FIG. 6 is a circuit diagram showing another modification of the switching means in the first embodiment. It is.

This embodiment is an example in which the present invention is applied to an optical disk device.

The optical disc device 1 is configured as follows.

As shown in FIG. 4, a spindle motor (not shown) is provided on the base 2, which has a cross section perpendicular to the longitudinal direction and is arranged so that the second side is open.
A turntable 3 supporting a disk (not shown) is attached to the drive shaft of this spindle motor. A cylindrical guide rail 4.4 is attached to the bottom side of the inner surface of the base 2 in parallel to the radial direction of the disk ('
I'm getting fucked.

Further, the carriage 7 on which the optical head 6 is mounted is formed into a rectangular tube shape on the right side of the hollow portion 8 extending in the axial direction of the rail 4. At the bottom of the carriage 7, there are, for example, three pairs of guide rollers 9 that engage with both guide rails 4.4.
is installed.

The carriage 7 is movable along the guide rails 4, 4 in the radial direction of the disk by the transfer of the guide [1-ra 9].

The carriage 7 is moved in the radial direction of the disk by a VCM (Poisniele Motor) having the following configuration. In other words, the carriage 7
A rectangular cylindrical bobbin 11 with a coil 10 wound around its outer periphery is provided in the hollow part 8, and this bobbin 11
2 to the bottom of the hollow part 8 of the carriage 7. On the other hand, a prismatic yoke 14 is installed on the base 2 at a position corresponding to the bobbin 11, into which the bobbin 11 is loosely fitted and extends parallel to the guide rail 4.

Further, on both sides of the yoke 14, supporting members 15°15
is provided, and on the inner surface of the support portions U15, 15,
A plate-shaped permanent magnet 16.16 is fixed. This permanent magnet 16.16 has a predetermined interval, and is connected to the coil 1.
I'm facing 0. By supplying current to the coil 10, the carriage 7 can be moved by the torque generated by the magnetic field by the permanent magnets 16, 16 and the current in the coil 10.

In this embodiment, in order to detect the position of the optical head 6, an optical linear encoder 20 as shown below is provided. An external scale 40 extending parallel to the guide rail 4 is attached to a mounting portion 21 protruding from one side of the carriage 7 via a school presser foot 22.

On the other hand, on the base 2, a light source, for example, an LED 25, is arranged at a portion corresponding to the external scale 40 from the outside of the base 21 toward the external scale 40, so that the light emitted from the LED 25 is approximately parallel. A lens 26 is incorporated therein.

Furthermore, a slit 50 and a photodetector 60 are attached to the inner surface of the base 2 at positions facing the LED 25 and the lens 26 with the external scale 40 in between. The external scale 40 and the slit 50 are formed with a bright and dark grid with a predetermined pitch arranged along the moving direction of the carriage 7. Then, as the external school 40 and the slit 50 move relative to each other, a rough stripe is generated due to the above-mentioned both paths. This moire fringe is detected by the photodetector 60 as a brightness signal.

Incidentally, in order to form moiré fringes on the photodetector 60, the distance between the external scale 40 and the slit 50 is set to 100 μm.
The outer scale 40 and the slit 50 should not come into contact with each other and damage the scale grating when the carriage 7 moves.

As shown in FIG.
For example, it has a lattice arranged at a pitch of 80 μm). A first fully transparent window portion (hereinafter referred to as inner gart band (1)) 43 consisting of a fully transparent portion 41 with a predetermined width is formed on the lower side of one end of the lattice. A second fully transparent window portion (hereinafter referred to as inner guard band (2)) 71/I is formed on the upper side, and includes a fully transparent portion 41 wider than the inner guard band (1) 43. ing.

Further, below the other end of the grating, a total reflection window portion (hereinafter referred to as outer guard band 1°) 45 consisting of a total reflection portion 42 having a predetermined width is formed.

On the other hand, in the center of the slit 50, a light amount monitoring window 51, which is a transmitting part, is installed.

The width of the light amount monitoring window 51 is an integral multiple of the grating pitch of the external scale 40, for example, 80 μm;
In order to prevent fluctuations in the amount of light when the external scale 40 moves, the number of output glue tools accompanying the movement of the external scale 40 is reduced. On both sides of this light amount monitoring window 51, slits 52 and 53 for generating moiré fringes are provided. Additionally, guard band detection windows 54 and 55 are provided at the upper and lower portions of the light amount monitor window 51.

Further, a photodetector 60 is disposed opposite the slit 50. As shown in FIG. 2, this photodetector 60 is located at a position facing the light @t monitor window 51 and is designated as a light amount monitoring phototransistor (hereinafter referred to as light amount monitoring phototransistor A to Tr). ) 61, and on both sides of the photo Tr 61 for monitoring the amount of light, there are scale signal photo 1 helangisters (hereinafter referred to as scale signal use) that face the moire fringe generating slits 52 and 53 and detect moire fringes.
tt-Tr-0) 62a, 62b are provided. Then, for each school signal, t t-T r
A phase difference is obtained by 62a and 62b. For example, the moiré fringe generation slit 52 is set so that each scale signal frame A1 to Tr62a, 62b has a 90 degree phase difference.
．． 53, and the outputs of the scale signal photo transistors 62a and 62b are shifted in phase by 90 degrees to generate signals obtained by dividing 360 melon into four. Further, above and below the optical M monitor foot Tr 61, phototransistors for guard band detection (hereinafter referred to as guard band detection) are provided opposite to the guard band detection windows 54 and 55.
It is written as Atorlr. )64.65 is installed.

In this embodiment, dirt on the external school 40, l ED
In order to prevent a decrease in the light reception tjl of each photodetector due to deterioration of the LED 25, a light amount control device for controlling the amount of light emitted from the LED 25 as described below is provided.

That is, as shown in FIG.
)V (current-voltage) conversion is performed by the IV converter 31 with ).

The I-V converter 31 is configured such that the inverting input terminal of the operational amplifier 32 serves as a signal input terminal, and the non-inverting input terminal is grounded. Further, the inverting input terminal and the output terminal are connected through a variable resistor 33, and by changing the resistance value of the variable resistor 33, the gain can be changed.

The output of the 1-V converter 31 is applied to a non-inverting input terminal of a differential amplifier 36 through a band-limiting low-pass filter (hereinafter referred to as LPF) 35. A first reference voltage VR1 having a target signal level is applied to the inverting input terminal of the differential amplifier 36.

The error signal from this differential amplifier 36 is a short bar and a relay switch.

Switch 37 using analog switch or FET, etc.
The signal is applied to one input terminal of the adder 38 via the . The other input terminal of this adder 38 is connected to a second reference voltage ■r2 which becomes the initial setting IFED current instruction value.
is applied. The output of the adder 38 is input as a current correction instruction value to a constant current drive circuit 39 that drives the LED 25, and these three constant current drive circuits
The current of ED25 is corrected.

Due to this feedback loop, the light source L
The linear encoder 20 controls the light intensity of the E D 25.
The amplitude of the output signal is kept constant.

Further, as shown in FIG. 3, the outputs of the scale signal photo transistors 62a and 62b are converted to 1-V converters 71a and 71brl-V, respectively, and are converted to 1-V by 1-V converters 71a and 71brl-V, and by a bleeder resistor 72a.
, 72b, a voltage for eliminating -C-A-noset is applied, and the gain is adjusted by variable amplifiers f73a and 73b.

The outputs of the variable amplifier 73a and variable amplifier 73b are:
The signal is input to a speed servo circuit 74 and a position servo circuit 75. The outputs of the speed servo circuit 74 and the position servo circuit 75 are connected to switches 76.7, respectively.
7 to the VCM drive circuit 78. Then, by this VCM drive circuit 78, V
The current of the CM coil 10 is controlled. The speed servo circuit 741 and the position servo circuit 75° switches 76 and 77 are controlled by a control circuit 79.

The outputs of the guard band detection photo transistors 64 and 65 are respectively connected to lV converters 81 and 81 with gain adjusters.
The signal is subjected to I-V conversion at 82, passed through LPFs 83 and 84, and then input to a comparison circuit 85. Then, in this comparison circuit 85, each guard band detection filter A1 to Tr6 is
The signal from 4.65 is compared with a reference value to detect the presence of each guard band, and the output of this comparison circuit 85 is input to the control circuit 79.

Next, the operation of this embodiment with the above configuration will be explained.

First, perform the initial settings as follows.

The switch 37 is opened, and the second reference voltage Vr2, which is the initial setting LED current instruction value, is input to the constant current drive circuit 39, and the LED 25 is caused to emit light at a current of 1o. The light that has passed through the external scale 40° slit 50 with the amount of emitted light at this time is received by the light-♀ monitoring foot Tr 61.

The output of this photo frame 1-r 61 is transferred to the I-V converter 31.
After converting the signal into T I - and V and passing it through T I-P F 35 , it is compared with first reference voltage Vr1 which is a target signal level in differential amplifier 36 . The gain of the I-V converter 31 is adjusted so that the comparison result ΔV becomes O.

1/1 Also, at this moment, photo Tr64 for guard band detection
．． 65 and scale signal outputs 62a and 62b, so that signals of the required size can be obtained.
-V converters 81 and 82 and variable 7 amplifiers 73a and 73b perform gain adjustment.

When the adjustment is completed, turn on the switch 37.

After the above initial settings, the optical disk device 1 is operated. In this case, as time passes, the light amount monitor
If the signal level of 61 does not change, the output V+=Vrl of the LPF 35 holds true, and the error voltage ΔV−O from the differential amplifier 36 is established, and the −ED 25 continues to emit light at the initially set light amount.

On the other hand, external scale 40. 50, etc., and the transmittance of the optical system changes, and the deterioration of L, E l) 25, etc.
When the signal from the light amount monitoring foot Tr 61 decreases, V+<Vrl, and an error voltage ΔV corresponding to the difference between the target values is generated. As a result, L E D 25
The current instruction value becomes Vr2+8V, the amount of light emitted from the LED 25 increases, and becomes stable when Vl reaches the target signal level ■r1.

Further, the magnitude of the guard band detection signal and the scale signal is maintained at the magnitude at the time of the initial adjustment in accordance with the above-mentioned light amount control. Conversely, when the signal from the light amount monitoring photo Tr 61 increases, the amount of light emitted from the LED 25 decreases.
It becomes stable when vl reaches the target signal level Vr1.

Signals obtained from the scale signal foot transistors 62a and 62b are input to a speed navigation circuit 742 and a position servo circuit 75. The speed servo circuit 74 controls the movement of the carriage 7 by setting the drive current of the VCM when the carriage 7 is moving, based on a signal from the control circuit 79 . Further, the position servo circuit 75 performs control to keep the carriage 7 at the target position when the gear ridge 7 reaches the vicinity of the target position. These controls are switched using switches 76 and 77 in response to signals from control circuit 79.

Furthermore, by comparing the signals from the photo transistors 64 and 65 for guard band detection with a reference voltage in a comparator circuit 85, the presence of each guard band 43, 4, 4, and 45 can be detected. Then, in accordance with this detection result, the set speed of the speed servo circuit 74, etc. are set based on the control circuit 79.

As explained above, according to this embodiment, at the time of initial setting, the feedback loop is heard, the LED 25 is made to emit light at the initial setting LED current instruction value, and the received light amount signal 1 of the next light amount monitoring photo Tr 61 is used as the reference. By adjusting the gain of the 1-V converter 31 so that it is at the same level as the voltage Vrl, even if the LED 25 deteriorates, the light J
When performing 1Y control, it is possible to prevent a large current from flowing and damaging the LED 25.

Also, LED25. Variations in each photo Tr61, as well as the luminous efficiency of IED25.

Variations in the photoelectric conversion efficiency of the photo Tr 61 can be absorbed by adjusting the received light amount signal v1 to the same level as the reference voltage Vr1.

Further, light is emitted from the ED 25, and an external scale 40,
Since the light passing through the slit 50 is detected by the photodetector 60 to control the light amount, the external scale 40. If the optical system of Surin 1 to 50 etc. is covered with dust, dirt, or scratches, the transmittance of the optical system changes, and the amount of light received by the scale signal photo transistors 62a, 62b, etc. Even if a change occurs such as a decrease in the amount of light, the amount of light can be controlled so as to keep the magnitude of the actual scale signal constant. Therefore, the output of the scale signal will not be insufficient due to an insufficient amount of light due to dirt on the external school 40, and the signal will not be detected to be smaller than the actual carriage speed. Therefore, an erroneous signal to increase the speed or the like is not issued, and the carriage 7 can be prevented from running out of control. Note that this applies not only to dirt on the external scale 40 but also to deterioration of the LED 25.

FIG. 5 shows a modification of the switching means in this embodiment. In FIG. 1, the feedback loop is cut off by the switch 37, but in this modification,
This is an example in which the output from the light amount monitoring photo Tr 61 can be cut off without cutting off the feedback loop. In this example, the switch 37 shown in FIG. 1 is not provided, and the output terminal of the differential amplifier 36 and the input terminal of the adder 38 are grounded via a switch 91.

At the time of initial setting, the switch 91 is closed and the adder 3
By setting the signal level input to 8 to O, L E D
25, the error from the reference voltage ■r1 does not work. Then, during adjustment, Vl is directly checked, not the output of the differential amplifier 736, so that it becomes the same as the reference voltage Vr1. Further, during actual use, it is sufficient to open the switch 91.

Furthermore, since the differential amplifier 36 is actually connected to the adder 38 at the time of initial setting, the output end of the adder 38 is grounded via a diode 92 in order to eliminate this influence.

FIG. 6 shows another modification of the switching means in this embodiment. In Figures 1 and 5, a switch is used, but in this modification, the switch is not installed. Therefore, at the time of initial setting, the differential amplifier 3
By setting the attenuation amount to be large, for example, −20 dB or more, the signal input to the adder 38 is suppressed to the extent that it does not affect the drive current of the LED 25, and the adjustment is performed.

FIG. 7 is an explanatory diagram that does not show the configuration of a light amount control device in a second embodiment of the present invention.

In this embodiment, the lens 26° external scale 40. Instead of slit 50 and photodetector 60, lens 126. External scale 123, sleeve l-12
7 and a photodetector 128 are provided.

The external scale 123 and the slit 127 are provided with a key 11.
A bright and dark grid with a predetermined pitch is formed along the moving direction of the ridge 7. When the external scale 123 and the sleeves 127 move relative to each other, moiré fringes are generated due to the gratings. This moire fringe is detected by the photodetector 128.

Note that the photodetector 128 has a light output element such as a four-divided frame A] to a diode, and also has a light output element such as a diode or the like.
is constructed by arranging at least two slits with different pitches so that the moiré fringes have a phase difference of 90 degrees in each photodetecting element.

Note that in order to form moire fringes on the photodetector 128, the distance between the external scale 123 and the slit 127 is set to 10.
The thickness should be approximately 0 μm to prevent the external scale 123 and slit 127 from coming into contact with each other and damaging the scale grating when the 21-trige 7 moves.

In such a linear encoder, the light emitted from the LED 25 is turned into substantially parallel light by the lens 126, and the light is converted into substantially parallel light by the external scale 123. The light passes sequentially through the slits 127 and is received by the photodetector 128. Here, when the carriage 7 moves, the external scale 123 and the slit 127 move relative to each other, causing [array fringes] to occur. The moiré fringes are detected by the photodetector 128, and based on the outputs of the four-divided photodetection elements of the photodetector 128, two-phase signals having a phase difference of 90 degrees, for example, are output. Based on this two-phase signal, address values are determined at a position interval of 1/4 of the bright/dark pitch of the external scale 123 using, for example, a circuit as shown in FIG. 6 of JP-A-57-181434. is,
The position of the carriage 7 is detected.

Note that the two-phase signal obtained from the linear 1 encoder actually has A frets 1 to 1 at the output stage of the photodetection element, so an electrical offset is added and the amplifier gain is adjusted to keep the amplitude constant. is being fine-tuned.

In this embodiment, the detection signal of each photodetection element of the photodetector 128 is input to an adder 133;
, a sum signal of detection signals whose phases differ by 90 degrees is output. The output of this adder 133 is converted from I to V by an IV converter 31 with a gain adjuster for initial setting, and is applied to the inverting input terminal of a differential amplifier 135 for offset removal. , is becoming a sea urchin. The differential amplifier 13
A voltage for offset removal is applied to the non-inverting input terminal of No. 5 via a bleeder resistor 136. The output of the differential amplifier 135 is output from the differential amplifier 36 similar to the first embodiment.
It is applied to the non-inverting input terminal of . The configuration of the stages subsequent to this differential amplifier 36 is the same as that of the first embodiment, and the first reference voltage Vrl is applied to the inverting input terminal of the differential amplifier 36, and the error The signal is applied via switch 37 to one input of adder 38 . A second reference voltage Vr2 is applied to the other input terminal of the adder 38.

The output of the adder 38 is a current correction instruction value, etc.
The constant current drive circuit 39 that drives the D25 is manually operated, and the constant current drive circuit 39 corrects the current of the LED 25.

In this way, in this embodiment, the sum signal of the outputs of the respective photodetecting elements of the photodetector 128 for position detection is used as the light amount monitor signal.

Other functions and effects of the configuration 1 are the same as those of the first embodiment.

FIG. 8 is an explanatory diagram showing the configuration of a light amount control device in a third embodiment of the present invention.

1st. In the second embodiment, the light intensity monitor is an external scale,
Although this is done using light that has passed through a slit, in this example, I
A portion of the light emitted from the ED 25 or the amount of light emitted from behind the ED 25 is directly detected by a photodetector, for example, the photodiode 141, and the photodiode 1
The amount of light is controlled based on the 41 horns. -4, that is, the output of the photodiode 141 is
The I-V converter 31 in the first embodiment is operated manually. The configuration of the stages subsequent to this IV converter 31 is the same as that of the first embodiment.

In this example, scale and slit dust.

The influence of dirt and the like cannot be taken into consideration, and the light amount control is performed only for changes in light amount based on deterioration of the LED 25 and output fluctuations.

The other functions and effects of the configuration 9 are the same as those of the first embodiment.

FIG. 9 is an explanatory diagram showing the configuration of a light amount control device in a fourth embodiment of the present invention.

The first to third embodiments relate to controlling the light amount of an LED used when detecting the position of an optical head using an external scale, but this embodiment is applicable to recording and reproducing information in an optical information recording/reproducing apparatus. reproduction.

Laser diode (hereinafter referred to as L) used for erasing etc.
Write it as D. ) is applied to light amount control.

The optical information recording and reproducing apparatus to which this embodiment is applied is mounted on a turntable 154 driven by a spindle motor 151, and an optical disc 152 that is rotationally driven by the spindle motor 151. Optical heads 6 are arranged to face each other. Inside this optical head 6, an LD 155 is provided. This LD15
The light beam emitted from the collimating lens 156
It is made into parallel light, transmitted through the polarizing beam splitter 157, made into circularly polarized light by the 1/4 wavelength plate 158, and then passed through the total reflection mirror 1.
The light is reflected by the light beam 59, focused by the objective lens 160, and irradiated onto the optical disc 152. The objective lens 160 is moved in the radial direction of the optical disk 152 and the objective lens 16 by an actuator (not shown).
It is movable in the optical axis direction of 0.

The return light from the optical disk 152 passes through the objective lens 160, is reflected by the total reflection mirror 159, passes through the quarter-wave plate 158, and is converted into linearly polarized light whose polarization direction is orthogonal to the outgoing path. The polarizing beam splitter 157
, and passes through the collimating lens 161 to form A1.
~The light is received by a photodetector 162 such as a diode.

Information recorded on the optical disc 152 is reproduced from the output signal of the photodetector 162. Further, the optical head 6 is movable in the radial direction of the optical disc 2 by, for example, a VCM.

In this embodiment, the output of the photodetector 162 is connected to the I-■ converter 3 with the initial setting gain adjuster in the first embodiment.
1 is entered.

The configuration of this I-V converter 31 to adder 38 is as follows:
This is the same as the first embodiment. The output of the adder 38 (yo,
The signal is input to an ID drive circuit 169 that drives the LD 155.

Due to this feedback loop, the light source L
The amount of light irradiated onto the optical disc 152 is kept constant by controlling the amount of light from the D155.

In this embodiment, the switch 37 is similar to the first embodiment.
Open it and perform the initial settings for open loop C1. Also,
Since the light from the LD 155 contains information signals, focusing signals, and dragging signals, after the return light from the optical disk 152 is detected by the photodetector 162, the light of the required magnitude is used as control signals for information reliability, focusing, and tracking. Perform gain adjustment to obtain the signal.

In this embodiment, the light amount monitor is connected to the optical disc 15.
2, but it is also possible to detect branched light in the optical path from the LED 155 to the optical disk 152, or detect part of the light between the light emitted from the LD 155 or the light reflected from the LD 155.
It is possible to internally detect the amount of light emitted from behind the light source and control the amount of light.

Other functions and effects of the configuration 9 are the same as those of the first embodiment.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be applied not only to optical information recording/reproducing devices but also to controlling the light amount of various light emitters.

[Effect 1 of the Invention] As explained above, according to the present invention, the switching means adjusts the output of the photodetector by the adjusting means while listening to the feedback loop, and then the switching means closes the feedback loop. By controlling the light amount of the light emitting body, it is possible to prevent the light emitting body from being destroyed when controlling the light amount, and it is also possible to absorb variations in the light emitting body and the photodetector.

[Brief explanation of the drawing]

Figures 1 to 6 relate to the first embodiment of the present invention.
Figure 2 is an explanatory diagram showing the configuration of the light amount control device, Figure 2 is an explanatory diagram showing the arrangement of the photodetector, Figure 3 is a block diagram showing the configuration of the circuit for controlling the carriage movement 9 positions, 5 is a circuit diagram showing a modification of the switching means in the first embodiment; FIG. 6 is a circuit diagram showing another modification of the switching means in the first embodiment; FIG. 7 is an explanatory diagram showing the configuration of a light amount control device in a second embodiment of the present invention, FIG. 8 is an explanatory diagram showing the configuration of a light amount control device in a third embodiment of the present invention, and FIG. 9 is an explanatory diagram showing the configuration of a light amount control device in a third embodiment of the present invention. In the fourth example of (
FIG. 2 is an explanatory diagram showing the configuration of a light amount control device.

Claims (1)

[Scope of Claims] A light-emitting body that converts electricity into light and emits light; a driving means that drives the light-emitting body; a photodetector that detects the light emitted from the light-emitting body; and a light-emitting body that detects the light intensity of the light-emitting body. a feedback loop that feeds back a signal based on the output of the photodetector to the drive means for control; and a feedback loop provided in the feedback loop that substantially directs the output from the photodetector to the drive means A light-emitting body characterized by comprising: a switching means capable of switching whether or not to transmit the light; and an adjusting means provided between the switching means and the photodetector and capable of adjusting the output of the photodetector. Light control device.