JPS63244421A - Multiple light-emitting device - Google Patents

Abstract

PURPOSE:To stabilize a light beam from each light source structure by separating a signal being the result of detection from a light beam radiated from plural light source structures of a light source by at least one photodetector into a signal component corresponding to each light beam, and using the said signal so as to control each light source structure. CONSTITUTION:A monitor photodetector 24 provided with a light sensing region 24A to monitor a reproducing/recording/erasure laser beam radiated from the rear face of the 1st, 2nd and 3rd laser structures 11-1, 11-2, 11-3 of a semiconductor laser 11 is placed. Plural laser beams from the laser structures are detected by the photosensing region 24A and a detection signal from the photosensing region is separated into a signal component corresponding to the reproducing/ recording/erasure laser beams by a signal separation circuit 80 and the semiconductor laser 11 is energized by a laser drive circuit 85 based on the separated reproducing/recording/erasure signal components. Thus, each light source structure is always driven accurately and stably.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multiple light emitting device having a plurality of light emitting points, and more particularly to a multiple light emitting device for controlling a light source device having a plurality of light emitting points.

(Prior Art) A semiconductor device in which non-laser beams are emitted from a plurality of light emitting points has been developed and is used in a light source device of an optical disk device.Generally, such a semiconductor device has one
There are semiconductor laser arrays that incorporate a plurality of laser structures in one chip, and semiconductor devices that incorporate a plurality of semiconductor laser chips in one package.

(Problems to be Solved by the Invention) Conventional semiconductor devices simply incorporate two or more laser structures, and the light emission of each structure is monitored by a detector, and the monitored signal is Since a structure that provides feedback is not adopted, the intensity of light emitted from each light emitting point is not stable, and there is a problem that the intensity of light emitted from each light emitting point fluctuates when the environmental temperature changes, etc. In addition, in devices where the distance between adjacent light-emitting points is small, simply placing a photodetector corresponding to each light-emitting point will not allow the laser beams from the adjacent light-emitting points to reach the corresponding photodetector. In addition, there is a risk that the light intensity of the laser beam may be incident on the adjacent photodetector, and there is a problem that the light intensity of the laser beam cannot be stably controlled. According to this invention, a particularly big problem is that a laser beam must be stably generated for reproduction, recording, or erasing, and the distance between the light emitting points is extremely small. a light source having a structure; a detection means having at least one detection area provided corresponding to a light emitting point of each light source structure and detecting a light beam from at least two or more light emitting points generated from the light source; separation means for separating a detection signal from the detection area of the detection means into signals corresponding to light beams from each light emitting point; and a separation means for driving each light source structure in accordance with the detection signal separated by the separation means; A multiple light emitting device is provided comprising driving means for controlling the light beam from each light emitting point.

(Function) Two or more light beams generated from a plurality of light source structures of the light source are detected in one detection area, and the detection signal is separated into signal components corresponding to the light beams from each light source structure by the separating means. Since the signals are separated into two and each light source structure is driven in response to the signal component, each light source structure is always driven accurately and stably.

(Embodiment) A case will be described in which an embodiment of an information recording/reproducing apparatus equipped with a multiple light emitting device of the present invention is applied to an optical head. As is clear, in the following explanation, the multiple light generator incorporated in the optical head will be explained, but the laser
It is obvious that the present invention can also be applied to printer devices or optical communication devices.

Optical head 5 of a multiple light emitting device according to an embodiment of the present invention
As shown in FIG. 2, a semiconductor laser 11 as a multiple light emitting device is arranged on the optical axis 1o of a condensing lens 12 which functions as a collimator lens and a projection lens. The light spot of the semiconductor laser 11 is located. Further, a focus and track detector 14 is arranged close to the semiconductor laser 11, and as shown in FIG.
And the detector 14 is fixed to the mount stand 2o. This semiconductor laser 11 has a reproducing laser, each having a light emitting point,
Three laser structures for recording and erasing 11-1.11-
2.11-3, and for example, three laser structures are built into one semiconductor chip, or a plurality of semiconductor devices having individual laser structures are built into one package. A diverging laser beam la is emitted from the semiconductor laser 11.

Lb and Lc are generated, but in the reproducing mode, only the reproducing laser beam la is generated, and in the recording mode, the recording, reproducing and erasing laser beam la is generated.
, lb, lc are generated, and in the erase mode, reproducing and erasing laser beams La, Lb, Lc are generated.

Here, the erasing beam LC is emitted in a more divergent manner than the other laser beams La and Lb by the cylindrical lens 8 provided in front of the light spot of the laser structure 11-3. This laser beam la.

-〇- The laser beam 1-c passes through the focusing lens 12, is converted into a collimated laser beam, and enters the prism 13. This prism 13 is connected to the optical axis 10 of the focusing lens 12.
Since the laser beam incident surface 13A is tilted relative to the collimated laser beam la, (-b, L
C, is incident on the laser beam entrance surface 13A and refracted, the laser beam having an elliptical cross section becomes the laser beam La, Lb, Lc having a circular cross section.
is converted to This laser beam La, Lb.

The LC includes a polarized beam that passes through the prism 13, is reflected by a polarized beam splitting surface 138 formed on the other surface of the prism 13, passes through a quarter-wave plate 15, and is focused onto the optical memory 1 by the objective lens 18. .

The laser beam focused on the optical memory 1 is reflected from this optical memory 1, and the reflected laser beam is
The light passes through the objective lens 18 and the quarter-wave plate 15, is introduced into the prism 13, and is returned to the polarized beam splitting surface 13S. Here, frame-f--1:'-frame La, Lb, L
Since the vibration direction of c is rotated by 90 degrees by reciprocating through the quarter-wave plate 15 compared to when it is reflected by the polarized beam split surface 133, the laser beams La and L
b, Lc are converted into linearly polarized laser beams by a quarter wave plate 15. Therefore, the laser beams La, Lb, L returned to the polarized beam split plane 138
G is the laser beam la, lb which is transmitted through this polarized beam splitting surface 13S and is joined to the polarized beam splitting surface 138.

It is introduced into the prism member 19 for dividing the LC.

As shown in FIG. 4, this prism member 19 has a first total reflection surface 19A and a second total reflection surface 19B which are non-parallel to the polarized beam splitting surface 138 and are adjacent to each other at an angle.
have. Here, the boundary line with the reflective surface 19A119B is determined to be approximately perpendicular to the direction in which the tracking guide is extended on the optical memory 1 or the direction in which the image of the tracking guide projected on the photodetector 14 is extended. ing. The first total reflection surface 19A is preferably formed flat, and the second total reflection surface 19B is formed an aspheric surface in order to impart astigmatism to the laser beam. The laser beams La, Lb, Lc reflected by the first total reflection surface 19A and the second total reflection surface 19B are transmitted to the first and second laser beams La-1, Lb-1, Lc, respectively. La-
2°Lb-2, Lc-1+LC-2 and directed in different directions, again deflected beam split surface 13S
The light passes through and enters the focusing lens 12.

First and second laser beams La-1°Lb-1,
La-2, Lb-2, Lc-1°Lc-2 are directed to a photodetector 14 provided on a mount base 20 together with the semiconductor laser 11 in close proximity to the semiconductor laser 11 by this focusing lens 12. a photosensitive area 16A of the photodetector 14;
16B.

17A and 17B are arranged substantially at the focal plane of the focusing lens 12, similar to the light spot of the semiconductor laser 1. Reflective surface 1
Laser beams La-1, Lb-1 reflected at 9A
The laser beam Lc-i is focused on a pair of photosensitive areas 16A and 16B for detecting focus errors, and the laser beam Lc-i reflected by the reflecting surface 19A is focused outside the pair of photosensitive areas 16A and 16B. focused on. In addition, the reflective surface 19
Laser beam La-2°Lb-2 reflected at B,
One of the Lc-2 is to detect tracking from the diffraction pattern generated when the laser beam is diffracted by the tracking guide.
A pair of photosensitive areas 17A and 17B for error detection
focused on. The laser beams 1a-2, Lb-2, and Lc-2 reflected by the reflective surface 19B are given astigmatism by the reflective surface 19B, which serves as an astigmatism surface, so that the laser beams 1a-2, Lb-2, and Lc-2 reach the photosensitive areas 17A and 17B. The focused laser beam has a beam spot stretched at right angles to the direction in which the tracking guide extends on the optical disk 1 or the direction in which the image of the tracking guide projected on the photodetector 14 extends. It is formed in the photosensitive areas 17A and 17B.

When the objective lens 18 is in focus, as shown in FIG. and a beam spot Sa1 is formed on the light-year sensing area 16C, and when the objective lens is in an out-of-focus state, the laser beam la is transmitted to the pair of photosensitive areas 16A of the photodetector 14, 16B, and the beam is directed to either of the pair of photosensitive areas 16A, 16B.
A spot Sa1 is formed. Thus, by processing the signals from the sensing areas 16A, 16B of the photodetector 14, a focus error signal corresponding to the state of the objective lens 18 is generated. Here, the detection slope 1 of the photodetector 14 is
The signal component corresponding to the beam spot Sb1 produced by the laser beam Lb-1 projected onto the laser beam Lb-1 projected onto the laser beam Lb-1 is similarly processed by the subsequent processing circuit and removed from the focused fist error signal. Also, when the objective lens 18 is directed toward the desired tracking guide and the desired tracking guide is correctly tracked by the laser beam, the photosensitive area 17A.

Laser beam La-2 generated on 17B
If a diffraction pattern of equal area occurs in the beam spot 3a2 and the desired tracking guide is not correctly tracked by the laser beam, the photosensitive area 17
Diffraction patterns of different areas occur within the second laser beam spot S82 occurring on A, 17B. Sensing area 17A.

By processing the signal from 17B, a tracking error signal is generated indicating whether or not the desired tracking guide is being correctly tracked by the laser beam.

Moreover, photodetection areas 16A, 16B, and 17A.

The signals from 17B are added together to reproduce the information.

As shown in FIGS. 2 and 3, the mount 20 has a cylindrical outer shape rotatable in the direction of the arrow, and the center of rotation of the mount 20 is aligned with the optical axis of the focusing lens 12. Therefore, the light emitting point of the semiconductor laser 11 is located at the rotation center of the mount 20. As a result, even if the mount 20 is rotated, the laser beam generated from the semiconductor laser 11 always travels along an optical path along a constant optical axis. When this mount 20 is rotated along the rotation direction (1), the sensing area 16A for defocus detection
, 16B are rotated in this direction.

Since the beam spot is moved substantially along the circumferential direction of the mount table 20 on the light sensing areas 16A and 16B depending on the defocus, the objective lens 18 must be moved when assembling and adjusting the optical head 5. While maintaining focus,
This mount base 20 is rotated so that the photosensitive areas 16A, 16
By forming a beam spot in the photon sensing region 16G between B, the optical system related to focus detection can be easily adjusted. Regarding the adjustment of the optical system for tracking and guide detection, the polarizing prism 13 is tilted while the objective lens 18 is maintained in a focused state to create a photon sensing area between the tracking and guide detection photosensitive areas 17A and 17B. Photosensitive areas 17A, 1 centered on 17G
7B has a detection beam for tracking and guide detection.
The arrangement of the polarizing prism 13 is adjusted so that a spot is formed. As shown in FIG. 5, preferably, defocus detection detection regions 16A, 16B and tracking guide detection light detection regions 17A, 17B are arranged on the mount 20 in the radial direction of the mount 20, respectively. mount 2
0 is rotatable and the light emitting point of the semiconductor laser 11 is located at the rotation center of the mount 20, so the optical system can be easily adjusted. In order to facilitate adjustment of the optical system, the mount 20 and the focusing lens 12 are integrally and rotatably supported by a lens barrel (not shown).

The optical system as shown in FIG. 2 is integrally supported by a head frame 28 as shown in FIG. Mount 2 supporting detector 14 and semiconductor laser 11
0 is the screw 27-1.27-2 on the head frame 28.
The mount 20 and the head frame 28 are further sealed with a hermetic seal 29 to protect the semiconductor element against ringing. According to the head structure shown in FIG. 5, the head can be made smaller and lighter. In addition, in the optical system shown in FIG.
The focusing lens 12 shown in FIG. 2 has been removed and the objective lens 18 has been replaced with an aspherical lens.

In the embodiment described above, the prism 13 has a laser beam entrance surface 13A that is inclined with respect to the optical axis 10 of the focusing lens 12. Therefore, when the collimated laser beam is incident on the laser beam entrance surface 13A and is refracted, the laser beam having an elliptical cross section is converted into a laser beam having a circular cross section.

Also, it is reflected by the reflective surface of the prism 13, and the condensing lens 1
2, the laser beam directed to surface 1 serves as a refractive surface.
3A, again changing its beam cross-sectional shape and substantially enlarging its diameter. By enlarging the beam diameter, the imaging magnification of the optical system increases, and the sensitivity for detecting defocus, that is, focus error, can be improved. In particular, in an optical system that employs the knife-edge method shown in Figure 2, the laser beam is stretched in a direction that is deflected according to the amount of defocus, so that the laser beam is deflected according to the amount of defocus. The sensitivity to deflection is improved, and the defocus detection sensitivity is improved.

An apparatus for energizing a semiconductor laser having a plurality of laser structures according to an embodiment of the present invention will be described with reference to FIGS. 1 and 6 to 9. FIG. As already explained, the semiconductor laser 11 is mounted on the stepped flat surface 22 of the semi-cylindrical base portion 2OA of the mount table 20 as shown in FIGS. 6 and 7.
On the flat surface 22 of the semi-cylindrical base portion 20A, which is placed and fixed on the semi-cylindrical base portion 20A and is spaced from the back surface of the semiconductor laser 11,
one optical sensor for monitoring the read, record and erase laser beams generated from the back side of the first, second and third laser structures 11-1.11-2.11-3 of this semiconductor laser 11; A monitoring photodetector 24 having a region 24A is mounted and fixed.

The semiconductor laser 11 has a structure incorporating two laser structures, and the interval between the light spots is usually 3 to i oooμ
It is set within the range of m. Preferably, the interval between adjacent light spots of the semiconductor laser 11 is usually set in a range of 3 to 160 μm, and more preferably, the distance between adjacent light spots of the semiconductor laser 70
The distance between the light spots is usually set in the range of 30 to 60 μm.

The reason why the above value is set is that when the lower limit of the distance between the light spots is usually 3 μm or 3 to 4 μm, electrical losstalk occurs between adjacent semiconductor laser structures 11-1 and 11-2. In this case, it is difficult to suppress the electrical crosstalk, and the optical axis 10 of the optical system
This is because it is difficult to match only one light spot. In addition, the upper limit of the interval between light spots is 1000 μm.
In this case, the distance between the beam spots formed on the optical disk 1 becomes large, and there is a possibility that the beam spots will not be guided by the tracking guide at the same time. Furthermore, the upper limit of 160 μm is determined as a limit value when the effective field of view of the focusing lens 12 and the imaging magnification of the optical system are taken into consideration so that the diameter of the beam spot formed on the optical disk 1 is 1 μm. It will be done.

Considering various points such as those mentioned above, the most preferable range is determined to be in the range of 30 to 60 μm.

In such a laser device, when multiple laser structures are activated and the laser beams generated from the structures are monitored, the multiple laser beams from the laser structures are directed to one photosensitive area 24A. The detection signal from this photosensitive area is separated into signal components corresponding to the reproduction, recording and erasing laser beams by a signal separation circuit 80 as shown in FIG. , the semiconductor laser 11 is energized by the laser drive circuit 85 based on the recording and erasing signal components. As shown in FIG. 1, the power supply voltage CC is applied to the photosensitive area 24A of the monitoring photodetector 24 and the first, second and third laser structures 11-1.
11-2.11-3 is connected to the first laser structure 1
1-1 is connected to the collector of the first transistor 32, and the second laser structure 11-1 is connected to the collector of the second transistor 33, the emitter of which is connected to the resistor 34. The third laser structure 11-3 is connected to the collector of a third transistor 36, the emitter of which is connected to ground via a resistor 37. The bases of these transistors 32, 33, and 36 are connected to a reproduction light control circuit 81, a recording light control circuit 82, and an erasing light control circuit 83, respectively. Further, the light sensing area 24A is connected to a signal separation circuit 80 via a preamplifier 35, and this circuit 80 is connected to a reproduction light control circuit 81 and a recording light control circuit 82.
, and the erase light control circuit 83. Therefore,
Based on the reproduction, recording and erasing signal components separated by the signal separation circuit 80, reproduction, recording and erasing base voltages are generated from the reproduction light control circuit 81, the recording light control circuit 82 and the erasing light control circuit 83, respectively. The internal impedance of each transistor 32, 33, 34 is determined based on the base voltage. As a result, the first, second and third laser structures 11-1, 11-2.
The laser beam generated from 11-3 is precisely controlled.

The circuit shown in FIG. 8 is specifically constructed of the circuit shown in FIG. In this circuit configuration,
The signal separation circuit 84 is a bandpass filter 40 . bottom level detection circuit 41, masking circuit 50, sample/hold circuit 54, erase light emission timing circuit 51,
The recording light separation circuit 84 is composed of a bandpass filter 40 and a bottom level detection circuit 41, and the recording light control circuit 82 is composed of a peak level detection circuit 42 and a bottom level detection circuit 41. 2 bottom level detection circuit 43, subtraction circuit 44, reference voltage generation circuit 45, recording base voltage generation circuit 46, recording signal generation circuit 47, and modulation circuit 48, and the reproduction light control circuit 81 is the reference voltage generation circuit. 56, a reproduction base voltage generation circuit 55, and an erase light control circuit 83 consisting of a reference voltage generation circuit 62, a recording base voltage generation circuit 66, and a switching circuit 64. That is, the bases of the transistors 33, 36 of the laser drive circuit 85 are connected to analog switches 37-1, 37-2, 37-3 of the analog switch device 37, which are turned on and off by command signals from the CPU 38, respectively. ing. The photo-sensing area 24A includes a band-pass filter 40 that passes a detection signal component having approximately the same frequency as that of the recording signal in order to extract a component corresponding to the recording signal generated from the recording signal generation circuit 45 via the preamplifier 35; The bandpass filter 40 is connected to a first bottom level detection circuit 41 that detects only the bottom level of the signal, and also connects to a peak level detection circuit 42 that detects the peak level of the detection signal corresponding to the recording signal and the recording signal. It is connected to a second bottom level detection circuit 43 that detects the bottom level of the detection signal corresponding to . The peak level detection circuit 42 and the second bottom level detection circuit 43 are connected to a subtraction circuit 44 in order to obtain the difference between the peak level and the bottom level. circuit 4
The base voltage generating circuit 46 is connected to a base voltage generating circuit 46 that generates an appropriate base voltage connected to the
is a modulation circuit 48 to which the recording signal generation circuit 47 is connected and which modulates the base voltage with the recording signal generated from this circuit.
It is connected to the. This switching circuit 48 is connected to the analog switch 37-1. The second bottom level detection circuit 41 is connected to an erasing light emission timing circuit 51 and is connected to a masking circuit 50 that masks a detection signal during erasing.
The output side of is connected to a sample and hold circuit 54 that samples and holds the bottom level, and this sample and hold circuit 54 samples and holds the signal from the second bottom level detection circuit 41 at the time of erasing. It is connected to a subtraction circuit 60 that subtracts a bottom level signal corresponding to the reproduced light component. The sample and hold circuit 54 is further connected to a base voltage generation circuit 55 which generates a base voltage for recording having an appropriate level and which is connected to a reference voltage generation circuit 56.
is connected to analog switch 37-2. Further, the subtraction circuit 60 is connected to an erasure base voltage generation circuit 66 to which a reference signal generation circuit 62 is connected, and this erasure base signal generation circuit 62 is connected to the erasure light emission timing circuit 51 via an inverter circuit 87. an erase base voltage generation circuit 64 that is connected to
The base voltage generating circuit 64 is connected to the third analog switch 37-3.

In such a circuit configuration, the second analog signal is output in response to the reproduction mode signal generated from the CPU 38 during the reproduction mode.
Switch 37-1 is closed. Therefore, the base voltage signal generated from the base voltage generation circuit 55 in accordance with the reference voltage generated from the reference voltage generator 45 is applied to the second transistor 33 via the second analog switch 37-2.
applied to the base of As a result, the second transistor 33 becomes conductive, activating the laser structure 11-1, and only a low level reproduction laser beam is generated from the laser structure 11-1. A reproduction laser beam generated from the front side of the semiconductor laser 11 is directed toward the optical disk 1, and a reproduction laser beam generated from the rear side thereof is incident on the photosensitive area 24A of the photodetector 24. In the reproduction mode, this reproduction laser beam is converted into a detection signal by the photo-sensing region 24A, this detection signal is amplified by the preamplifier 35A, and the bottom signal is detected by the bottom level detection circuit 41. Here, since the reproduction laser beam is generated at a constant level, the detection signal from the photosensitive area 24A is also at a constant level, and therefore, the bottom level detection circuit 41 detects the bottom signal at the constant level. . In the reproduction mode, the erasing light emission timing circuit 51 does not generate an erasing timing signal, so the masking circuit 50 remains inactive. Therefore, this bottom signal is passed through the masking circuit 50 to the sample and hold circuit 54.
sample and hold. This sample
The hold circuit 54 samples and holds the updated level every time the bottom signal is updated. This sampled and held bottom signal is compared with a signal in a reproduction base voltage generation circuit 55, and based on the comparison result, a feedback-controlled base voltage signal is generated from the base signal generation circuit 55. When this feedback controlled base voltage signal is applied to the base of transistor 33, the internal impedance of transistor 33 is changed such that the regenerative laser beam generated from laser structure 11-1 is maintained constant. .

In the recording mode, the first and second analog switches 37-
1.37-2 is closed. Therefore, as in the reproduction mode already described, a base voltage signal for reproduction is generated, and in addition to this voltage signal, a base voltage signal for recording is also generated. That is, the reference voltage signal is generated from the reference voltage signal generation circuit 45 in response to the recording signal generated from the recording signal generation circuit 47,
Recording base voltage signal generator 48 via subtraction circuit 46
The reference voltage supplied to is modulated with the recording signal, and the modulated base voltage signal is applied to the base of transistor 32 via analog switch 37-1. As a result, the internal impedance of the transistor 32 changes in response to the modulated base signal, and the current supplied to the laser structure 11-1 changes in a pulsed manner. Therefore, a reproduction laser beam and an intensity-modulated recording laser beam are generated from the laser structures 11-1 and 11-2. This recording laser beam is detected by the photosensitive area 24A of the photodetector 24, as in the playback mode, and converted into a detection signal.

This detection signal is supplied to a bandpass filter 40 and a bottom level detection circuit 41 via a preamplifier 35. The bottom level of the detection signal supplied to the bottom level detection circuit 41 is detected and the component corresponding to the recording signal is removed. This bottom signal extracted from the detection signal is processed in the same manner as in the reproduction mode described above, and the reproduction base voltage is maintained constant. Bandpass・
From the detection signal supplied to the filter 26 - filter 40, only the modulation frequency component corresponding to the recording signal is extracted, and the component corresponding to the reproduction base voltage signal is removed. The detection signal that has passed through the bandpass filter 40 is sent to a peak level detection circuit 4.
At step 2, the peak level is detected, and at the same time, at the bottom level detection circuit 43, the bottom level is detected. The difference between the detected peak level and bottom level is generated from the subtraction circuit 44. This level difference signal is compared with a reference voltage signal in the base voltage generation circuit 46, and a recording base voltage signal having a constant peak level that determines the peak level of the recording laser beam is generated from the base voltage generation circuit 46. Ru. This recording base signal is modulated by a modulation circuit 48 in accordance with the recording signal to generate a modulated base voltage signal. Since the recording laser beam is monitored and the peak level of the base voltage signal applied from this monitor output to the base of transistor 32 is always maintained constant, the laser tI!
The peak level of the laser beam generated from the fourth structure 11-2 is maintained constant.

In the erase mode, the second and third analog switches 37-2 and 37-3 are closed in response to the erase mode signal generated from the CPU 38. Therefore, as in the playback mode described above, the playback base is closed. A voltage signal is generated, and in addition to this voltage signal, an erase base voltage signal is generated. That is, the erase light emission timing signal generation circuit 5
The masking circuit 5o is activated by the erase timing signal generated from the erase timing signal 1, and the switching circuit 64 is also activated to connect the erase base voltage generating circuit 66 to the analog switch 37-3. Therefore, the reference signal generation circuit 6
2 and supplied to the erase base voltage signal generator 66 is applied to the base of the transistor 36 via this switching circuit 64 and the analog switch 37-3. As a result, the erasing base voltage signal activates transistor 32 and laser structure 1
An erasing current is supplied to 1-3. Here, since the base voltage signal for reproduction is also applied to the base of the transistor 33, this transistor 33 is also activated. Therefore, a reproducing laser beam is generated from the laser structure 11-1, and the laser structure 11-1 also generates a reproduction laser beam.
-3, an erasing laser beam is generated. This regeneration and erasure laser beam is transmitted to a photodetector 24.
is detected in the photosensitive area 24A. The detection signal from the sensing region 24A is supplied to the bottom level detection circuit 41 via the preamplifier 35A. Bottom level detection circuit 41
The bottom level of the detection signal supplied to the masking circuit 50 is detected and supplied to the masking circuit 50 . Here, the masking circuit 50 is masked because it is maintained in an activated state by the timing signal from the erasing light emission timing signal generation circuit 51. Therefore, in the erase mode, the reproduction laser beam is detected before the erase timing signal generated by the erase light emission timing signal generation circuit 51 is generated, and the signal level is sampled and held by the sample and hold circuit 54. A base voltage signal for reproduction is determined. Even when a recording laser beam is generated in the erase mode, the recording signal level included in the detection signal is removed by the bottom level detection circuit 41. The bottom signal from the bottom level detection circuit 41 includes:
Although the reproduced light component is included as noise, this reproduced light component corresponds to the bottom detection signal for reproduction sampled and held by the sample and hold circuit 54, and therefore, the signal from the sample and hold circuit 54 and the bottom detection signal are sampled and held by the sample and hold circuit 54. By supplying the bottom detection signal from the circuit 41 to the subtraction circuit 60, the reproduced light component as noise contained in the bottom signal is removed from the bottom detection signal. The base generation circuit 6 generates a bottom detection signal for reproduction from which noise has been removed.
6, this bottom detection signal and the reference signal are compared in an erasing base generation circuit 66 to generate an erasing base voltage signal. Therefore, the level of the erasing laser beam generated from laser structure 11-3 is maintained constant.

The circuit shown in FIG. 1 may be modified as shown in FIG. In FIG. 9, circuit components similar to those shown in FIG. 1 are given the same reference numerals, and their explanations are omitted.

In the circuit shown in FIG. 9, the signal separation circuit 80 includes the peak level detection circuit 42 and the masking circuit 50-1.
．． 50-2, sample hold circuit 54-1.54-2
, bottom level detection circuit 41, M quasi-voltage generation circuit 88
, a subtraction circuit 60, a recording signal generation circuit 47, an erase signal generation circuit 51, and inverter circuits 87-1 and 87-2. Therefore, the second analog switch 37-1 is closed in response to the reproduction mode signal generated from the CPU 38 during the reproduction mode, and the base voltage signal generated from the base voltage generation circuit 55 is applied to the base of the second transistor 33. is applied to generate only a reproducing laser beam from the reproducing laser structure 11-1, which is detected in the first photosensitive area 24A. In the reproduction mode, since no high-level recording signal is generated from the recording signal generation circuit 47, detection from the photosensitive area 24A is performed via the first masking circuit 50-2, which is maintained in an inactive state. The signal is supplied to the first sample and hold circuit 54-2 and sampled and held. This sampled and held detection signal is sent to the reproduction base voltage generation circuit 55.
Based on the comparison result, the base signal generating circuit 55 generates a feedback-controlled base voltage signal. When this feedback controlled base voltage signal is applied to the base of transistor 33, the reproduction laser beam generated from laser structure 11-1 is maintained constant.

In the recording mode, the first and second analog switches 37-
1.37-2 is opened. Therefore, as in the reproduction mode already described, a base voltage signal for reproduction is generated, and in addition to this voltage signal, a base voltage signal for recording is also generated. That is, the reference voltage signal is generated from the reference voltage signal generation circuit 45 in response to the recording signal generated from the recording signal generation circuit 47,
Recording base voltage signal generator 48 via subtraction circuit 46
The reference voltage supplied to the transistor 32 is modulated with the recording signal, and the modulated base voltage signal is applied to the base of the transistor 32. As a result, a reproducing laser beam is generated from the laser structure 11-1, and a recording laser beam is generated from the laser structure 11-2 in response to the modulated base signal. The reproduction laser beam and the recording laser beam are transmitted to the photosensitive area 2 of the photodetector 24.
4A, and a detection signal in which the recording detection signal level is mixed as noise with the reproduction detection signal level is generated from the photosensitive area 24A.

The detection signal from the photosensitive area 24A via the preamplifier 35 is supplied to the masking circuit 50-2. Since the masking circuit 50-2 is maintained in an activated state, the detection signal is masked by the masking circuit 50-2. Therefore, the reproduction base voltage is determined based on the sampled and held detection signal before the detection signal is masked. Since the inverter 87-2 is connected between the second masking circuit 50-2 and the recording signal generation circuit 47, the second masking circuit 50-2 receives the recording signal from the recording signal generation circuit 47. It is maintained in an inactive state while a signal is being generated, and is maintained in an open operating state in which no recording signal is generated from the recording signal generating circuit 47. Therefore, the detection signal from the recorded moonlight sensing area 24A is detected by the peak level detection circuit 42, and the detected peak level is sent to the sample and hold circuit 54-1 via the masking circuit 50-1, which is maintained in an inactive state. The signal is sampled and held at 1 and supplied to the base voltage generation circuit 46, and the base voltage is determined based on the reference voltage from the reference voltage generation circuit 45. This recording base signal is modulated by a modulation circuit 48 in accordance with the recording signal to generate a modulated base voltage signal.

In the erase mode, the second and third analog switches 37-2, 37-3 are closed in response to an erase mode signal generated from the CPU 38.

Therefore, as in the reproduction mode already described, a base voltage signal for reproduction is generated, and in addition to this voltage signal, a base voltage signal for erasing is also generated. That is, the masking circuit 50-1, 50-2 is activated by the erase timing signal generated from the erase light emission timing signal generation circuit 51, and the switching circuit 64 is also activated, so that the erase base voltage generation circuit 66 is activated by the analog switch 37. -3 is connected. Therefore, the reference signal generation circuit 62 generates
The reference voltage supplied to the erase base voltage signal generator 66 is applied to the base of the transistor 36 via this switching circuit 64 and the analog switch 37-3. As a result, the erase base voltage signal activates transistor 32 and provides erase current to laser structure 11-3. Here, since the base voltage signal for reproduction is also applied to the base of the transistor 33, this transistor 33 is also activated. Therefore, the laser structure 11-1 generates a reproducing laser beam, and the laser structure 11-3 generates an erasing laser beam. The regeneration and erasure laser beams are directed to the photosensitive area 24 of the photodetector 24.
Detected at A. The detection signal from the sensing region 24A is supplied to the bottom level detection circuit 41 via the preamplifier 35A. The bottom level of the detection signal supplied to the bottom level detection circuit 41 is detected.

Even when a recording laser beam is generated in the erase mode, the recording signal level included in the detection signal is removed by the bottom level detection circuit 41. The bottom signal from the bottom level detection circuit 41 includes a reproduction light component as noise, and this reproduction light component is generated by the correction signal generation circuit 88. That is, assuming that the reproduction light level is substantially constant, a correction signal corresponding to the reproduction light level is generated from the correction signal generation circuit 88. By supplying this correction signal and the bottom detection signal from the bottom level detection circuit 41 to the subtraction circuit 60, the reproduced light component as noise contained in the bottom signal is removed from the bottom detection signal. The erasing bottom detection signal from which noise has been removed is supplied to the erasing base generation circuit 66, and this bottom detection signal and the reference signal are used as the erasing base voltage generating circuit 6.
6 to generate an erase base voltage signal.

Therefore, while the erase light emission timing circuit 64 is in the activated state, the erase base voltage signal is applied to the base of the transistor 36 to maintain a constant level of the erase laser beam generated from the laser structure 11-3. Ru.

[Effects of the Invention] As described above, according to the optical head equipped with the multiple light generating device of the present invention, the light beams generated from the plurality of light source structures of the light source are detected by at least one photodetector. The detection signal is separated into 1 signal components corresponding to each light beam,
Since each light source structure is thereby controlled, each light source structure is always driven accurately and stably, and as a result, the light beam from each light source structure is also stabilized. Therefore, information can be accurately reproduced from the information recording medium, information can be recorded,
Or it can be deleted.

[Brief explanation of the drawing]

FIG. 1 shows a circuit diagram of a multiplexed light generator according to an embodiment of the present invention, and FIG. 2 shows an optical system of an optical head in which the multiplexed light generator shown in FIG. 1 is incorporated. Figure 3 is
FIG. 2 is a front view showing the mount shown in FIG. 2, FIG. 4 is a perspective view showing the prism member shown in FIG. 2, and FIG. 5 is a front view showing the mount shown in FIG.
FIG. 2 is a sectional view showing the mount frame in which the optical system shown in FIG. 6 is incorporated, FIG. 6 is a perspective view showing the mount shown in FIG. 3, and FIG. FIG. 8 shows a block diagram of a circuit diagram of a multiplexed light generating device according to the present invention, and FIG. 9 shows a circuit diagram of a multiplexed light generating device according to another embodiment of the present invention. 11... Semiconductor laser, 12... Focusing lens, 1
3... Prism, 14... Photodetector, 16A, 16
B, 17A, 17B... Light sensing area, 18... Objective lens, 20... Mount, 24... Photodetector for monitor, 24A, 24B... Light sensing area, 38...
CPU, 40... Bandpass filter, 41.4
3... Bottom level detection circuit, 42... Beef level detection circuit, 44... Subtraction circuit, 46.55°66.
... base voltage generation circuit, 48 ... modulation circuit, 50.
50-2.50-2... masking circuit, 51...
Erasing light emission timing circuit, 54.54-1.51-2
...Sample/hold circuit, 60...Subtraction circuit,
88...Correction signal generation circuit Applicant's agent Patent attorney Takehiko Suzue Figure 6 Vcc

Claims (4)

[Claims] (1) A light source having a plurality of light source structures, and at least one detection area provided corresponding to the light emitting points of each light source structure and detecting light beams from at least two or more light emitting points generated from the light source. a detection means having a detection area of the detection means, a separation means for separating a detection signal from a detection area of the detection means into signals corresponding to a light beam from each light emitting point, and a separation means for separating a detection signal from each light source structure according to the detection signal separated by the separation means. 1. A multiple light emitting device comprising: driving means for driving a body and controlling light beams from each of the light emitting points. (2) The separation means is characterized by comprising a filter circuit that removes a specific component from the detection signal from the detection area, and a circuit that subtracts the output signal of this filter circuit from the detection signal from the detection area. A multiple light emitting device according to claim 1. (3) The separating means includes a filter circuit that removes a specific component from the detection signal from the detection area, a sample and hold circuit that holds the output signal from the filter circuit for a specific period, and a sample and hold output signal that 2. The multiple light emitting device according to claim 1, further comprising a subtraction circuit that subtracts the detection signal from the detection area. (4) The signal separation circuit is characterized by comprising a filter circuit that removes a specific component from the detection signal from the detection area, and a sample and hold circuit that holds the output signal from the filter circuit for a specific period of time. A multiple light emitting device according to claim 1.