JPS61261828A - Light source device for optical information recording and reproducing - Google Patents

Abstract

PURPOSE:To monitor projection-side luminous flux securely by detecting laser diodes put in multiple constitution by a photodetectors composed of plural photodetecting elements through a lens. CONSTITUTION:The quantities of pieces LMA and LMB of monitor-side luminous flux of two laser diodes 2A and 2B which are photodetected by photodetecting elements 4A and 4B are converted photoelectrically into electric signals having levels corresponding to their quantities of photodetection, and they are inputted to and amplified by amplifiers 5A and 5B. Those signals amplified by the amplifiers 5A and 5B are applied to one-terminal sides of comparators 7A and 7B through LPFs 6A and 6B respectively. A reference voltage VR for reading and a reference voltage VW for writing are applied to the other-terminal sides of the comparators 7A and 7B and the amplified signals are compared with the reference voltages VR and VW and their variation components are applied to, for example, control terminals of LD driving circuits 8A and 8B. Thus, currents supplied to the laser diodes 2A and 2B are controlled with the voltages applied to the control terminals.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an optical information recording/reproducing light source device suitable for controlling a light emitting device of multiple semiconductor lasers.

[Prior Art] In recent years, instead of devices that use magnetic heads to record and reproduce information, optical beams have been used to record information at high density, or to record information at high speed. Optical information recording or information reproducing devices that can be reproduced and reproduced have attracted attention.

In the above-mentioned optical apparatus, in order to perform high-density recording or re-recording on a recording medium, it is necessary to perform focus control and racking control means with high precision.

For this reason, an example of a system that can cope with this problem by using multiple light sources is shown in Japanese Patent Publication No. 18772/1983.

In addition, by using multiple light sources, it has become possible to detect recording errors and defects in real time.
The described D RAW 1[) array optical head has two beams, 1. Using a D (laser diode) array,
By reading the data immediately after recording, it is possible to detect recording errors, defects, etc.

Further, Japanese Patent Application Laid-Open No. 55-113390 discloses an APC (Automatic Light Output Control) circuit that uses a Peltier element to provide temperature compensation.

[Problems to be Solved by the Invention] When the above-mentioned multi-layered LD array is used, the LU
), the monitor output will be the total output of the array, and it will not be possible to detect the output of each LD. Unable to control output. Therefore, the S/N ratio in the recording or reproduction mode decreases, the incidence of recording errors and reproduction errors increases, and highly reliable control becomes impossible.

The invention has been described above! ,: It was made in view of the points,
It is an object of the present invention to provide a light source device for a young optical information recording/reproducing device that can perform highly reliable automatic light output control.

[Means and actions to solve the problem] With this device, [
Monitor luminous flux L of J1 multi-layered laser diode 2
MA, l-MB are transmitted through a lens 3 to a plurality of light receiving elements 4.
By using a structure that can be detected by the photodetector 4 consisting of Δ and 4B, it is possible to reliably monitor the output side luminous flux '-FA''-FB, respectively.

[Example] Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIG. 1 shows a ΔPC circuit using a first embodiment of the present invention, and FIG. 2 shows a specific configuration of the first embodiment.

The light source device 1 of the first embodiment includes two laser diodes (L
D) Laser diode array 2 consisting of laser diodes 2A and 2B, and the monitor side light beam 1-
Lens 3H8 H8 arranged at 1l-, J to this lens 3, each laser diode 2A
, 2B consists of a photodetector 4 consisting of two light-receiving cables 4A and 4B, such as two pin diodes 4A and 4B, arranged at a position where the light beams of 2B are separated.

The amount of monitor light received by each of the light receiving elements 4A, 4B is photoelectrically converted into an electrical signal having a level corresponding to the amount of light received, and is input to amplifiers 5A, 5B and amplified. Each of these amplifiers 5Δ.

The signals amplified by 5B are each passed through a low-pass filter (l
PF) 6△, 6B are applied to one input terminal of the comparator 7△, 7B. A reference voltage VR for reading and a reference voltage Vw for writing are applied to the other input terminal (non-inverting input terminal) of each comparator 7A, 7B, respectively, and are compared with the reference voltages VR, Vw, respectively, and their fluctuations 1-D drive circuit 8A each.

For example, the voltage applied to the control end of the laser diode 8B is applied to the control end of the laser diode 2A.

This allows the current supplied to 2B to be controlled.

For example, as the optical output of the laser diode 2A decreases, the light flux L-1 on the exit 4 side and the light flux EA on the monitor side decrease.
The optical output of both EB L and l- decreases and passes through lens 3 to HA.
The amount of light received by the HB light-receiving element 4A decreases, and therefore its photoelectric conversion output level also decreases. Therefore, the output level of the comparator 7A is approximately 4, and the drive circuit 8A increases the supplied current to increase the optical output and functions to prevent the -F light distribution output from decreasing. The other laser diode 2B is similarly controlled. In this way, each laser diode 2△
, 213, a ΔPC circuit is activated to keep the optical output constant.

In the first embodiment, one of the ray IJ" diodes 2B
is used for reading, and the other laser diode 2A is used for writing. Therefore, the drive circuit 8 on the line L- side
Data to be recorded to the data input terminal is applied to B, and when this data is at a high level, the laser diode 2
B emits light in a pulsed manner, and recording corresponding to the 1-record data is performed on an optical recording medium (not shown).

According to the first embodiment, each laser diode 2A, 2
The light beams B are separated and received by the light receiving elements 4A and 4B through the lens 3, respectively, and the light outputs of the corresponding laser diodes 2A and 2B are controlled by the separated light reception outputs.

Therefore, each laser diode 2Δ, 2B can be appropriately controlled without being interfered with by the other laser beam. Therefore, if this light source device 1 is used as a light source for an optical information recording/reproducing box, recording or reproduction can be performed at an appropriate level.

Further, by using the lens 3, the amount of light used for monitoring can be increased, and good S/N ratio control can be performed.

Figure 2 shows light source S! The specific structure of Placement 1 is shown below. As shown in the figure, the optical device 1 has a substantially disc-shaped base 12 and a cylindrical portion 14 whose open upper end is closed with glass 13 or the like to form a sealed package. A heat insulating block 15 having a substantially semi-cylindrical shape is fixed to the upper surface of the base 12 in the sealed space inside the cylindrical part 14, and a heat generating block 15 which has a self-temperature control function, such as a positive temperature reamister, is mounted on this block 15. Element 16 is fixed. A thermally conductive plate 17 is closely fixed to the further side of this heating element 16, and this plate 1
A laser diode eyelet 2 is fixed on top of the laser diode 7 .

This laser diode array 2 has, for example, an n-layer and a 0-layer active layer arranged in the form of a lean switch, and by applying a forward bias to both sides, laser light is output from both end faces on the mirror surface. In this case, one end surface becomes the output Q4 side end surface, and the other end surface becomes the monitor side end surface, and the light beams emitted from the -power end surface side, that is, the output side light beams LEA, LEB. is emitted through the glass 13, and from the other end surface is the monitor side light flux LMA,
l-, MB are emitted.

By the way, a semicircular board 19 is fixed to the upper surface of the stand 12 inside the cylindrical part 14, and this board 19
A photodetector 4 (4T apart from the light receiving elements 4A, 4B) is fixed at a position substantially facing the end face of the laser diode array 2 on the ``-'' plane. Further, adjacent to this photodetector 4, for example, a semi-cylindrical support frame 21 has one end fixed to the substrate 19, and a lens 3 fixed to the other end. Above stand 12
Several pins 22a, 22b, 22c, . . . are provided protruding from the top, and these pins 22a, 22b, .

In this way, the laser diode 2, the photodetector 4, and the lens 3 are housed in a sealed cylinder, for example, and each monitor light flux 1-+1A, l- of the laser diode 2A, 2b is
This is to separate Mu and guide it to the light receiving cables 4A and 4B. Therefore, if an APC circuit is configured using this embodiment, each output side light beam LEA, 1. Appropriate optical output control can be performed for Ee. Furthermore, since it is thermally isolated from the outside world by the heat insulating block 15 (although not shown in FIG. 1) and a self-warming stone control type heating element 16 is installed,
By supplying current to this element 16 from a constant voltage source or the like, the laser diode array 2, which is thermally coupled by the thermally conductive plate 17, can be maintained at a constant temperature. For example, when the laser diode array 2 is activated and its hot stone is low, the current flowing through the heating element 17 is large, causing the temperature to rise. If the temperature on the side of the laser diode array 2 becomes too high, such as when a car minute has passed after operation, the current flowing through the heating element 17 will be small and the amount of heat generated will be reduced to keep the temperature constant. can.

In this way, the current of the photothermal element 17 is automatically controlled so that the temperature around the element 17 is constant. The heating element 17 is replaced by a laser diode array 2
Since it is thermally coupled to a predetermined operating temperature, it can be quickly set to a predetermined operating temperature and maintained at that temperature.

FIG. 3 shows an APC formed using the second embodiment of the present invention.
Show the circuit.

This embodiment is for the case where there are two different wavelengths.

In this second embodiment, for example, a three to four laser diode array 32 is used, in which laser diodes 32A and 32C having different wavelengths from the laser diode 32B are provided on both sides of a central laser diode 32B. Motor luminous flux l of this laser diode array 32
- MA, 1M e, L-M c (Illo Achromer 1 to lens 33. - A photodetector 35 is provided with an interference filter 34 interposed. Also, the interference filter 3
A pair of light receiving elements 36 are placed on the side of the optical path reflected in the right angle direction by
Δ, photodetectors 36 from 36C to 4T are provided. The achromatic lens 33 functions as a lens for laser beams of two different wavelengths from the laser diodes 3213; 32A and 32G without producing chromatic aberration. Further, the interference filter 34 utilizes the interference phenomenon to filter the laser beam 1- of the laser diode 32B, for example.
MB is transmitted through I, and the other (pair of) laser diodes 3
The laser beams LMΔ and l-MC of 2A and 32C are reflected and guided to the photodetector 36. The output of the photodetector 35 is amplified by an amplifier 5B, passes through a low-pass filter 6B, and is input to an axis ratio device 7B. This part is similar to that in FIG.

On the other hand, the output of the photodetector 36 is amplified by the outputs of the light receiving elements 36A and 36B by the amplifier 5/M, and is input to the comparator 7A via the low-pass filter 6A. In this second embodiment, for the case of two different wavelengths,
Each optical output for reading can be controlled independently. Therefore, it is possible to record with appropriate optical output and to perform reproduction with fewer errors. 1-2 When storing the second embodiment in a package, in the light source 1 shown in FIG. ) Support frame 2・
Interference filter 34 fixed at 1. A photodetector 35 may be fixed below the filter, and a photodetector 36 may be fixed within the side of the interference filter 34 via a support or the like.

FIG. 4 shows a structure for more securely fixing the lens 3 and photodetector 4 shown in FIG. 2. That is, on the emission side of the monitor-side light beams 1-MA and 1-MB of the laser diode array 2, a cylindrical frame 41 made of metal or the like is fixed at its lower end to the substrate 19. A lens 3 is fixed to the upper end side of this cylindrical frame 41, and a photodetector 4 is fixed to a substrate 19 inside the cylindrical frame 41.

In addition, instead of lenses 3 and 33, selfoc lenses or
A [ ]gram lens may also be used.

FIG. 5 shows an embodiment in which a laser diode array holder (lr array holder) 51 is used as a lifting platform which is separate from a photodetector holder.

That is, the flange 52 of the LD array boulder 51 has the same shape as the flange 53 of the cylindrical holder 54.
3 to the flange 52 of the LD array holder to form an integrated package.

2. A lens 58 is fixed (through a glass 57 or directly) on the side of the cylindrical holder 54 facing the transparent base 56 to which the laser diode array 55 of the L O array voluda 51 is fixed, and a photodetector is mounted below the lens 58. 59 is attached so that the monitor light beam of the laser diode array 55 can be separated and received. Note that the laser diode array 55 is configured so that the light beam on the output side is emitted through the glass 60.

By the way, the monitor light flux 1-MA shown in FIG.

l-Mc can also be used alone in other than APC circuits, such as APC circuits such as 1-racking and focusing. In addition, a thermal lightning cooling element (for example, installed in place of the heating element in Fig. 2, or installed at another location) can be thermally coupled to the laser diode array to prevent the laser diode array from drying out. It can also be held constant. In addition, when installing it together with a heating element, first raise the heating element to the operating temperature. ,
The laser diode array may be operated by switching between a heating element and a cooling element depending on the temperature of the diode array.The present invention is not limited to the above-mentioned, A photodetector consisting of a plurality of light receiving elements (which may or may not be the same number as the above-mentioned light emitting elements) is connected through a lens to a semiconductor light emitting element array consisting of a diode (or ED) or the like. The present invention can be widely applied to devices that separate and receive light.Furthermore, the present invention can be widely applied to at least one of recording and reproducing on an optical recording medium, and various types of control in these cases.

[Effects of the Invention] Depending on the application, the light emission output can be accurately detected, and when used in various devices, the device can be operated stably in a highly reliable state.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an automatic light output control circuit using one embodiment of the present invention, FIG. 2 is a perspective view showing the specific structure of the first embodiment, and FIG. FIG. 4 is a configuration diagram showing an automatic light output control circuit using an embodiment, and FIG.
The figure is a sectional view of still another embodiment of the present invention. 1... Light source device 2... Laser diode array 2
△, 2 [3... Laser diode 3... Lens 4
...Photodetector /IA, 4B...Photodetector 5A, 5
B...Amplifier 7△, 7B...Comparator 8A, 8B.
・・Drive circuit

Claims (2)

[Claims] (1) In a light source device for an optical information recording/reproducing device that performs at least one of recording or reproduction by irradiating a light beam onto an optical recording medium, light beams are emitted from multiple locations on both end faces. An optical information recording/reproducing light source comprising a laser diode array and a photodetector comprising a plurality of light receiving elements that receive light through a lens on a monitor end surface opposite to one end surface of the laser diode. Device. (2) The optical information recording/reproducing light source device according to claim 1, wherein the laser diode array, lens, and photodetector are housed in the same package.