JPH02149940A - Controller for laser bea - Google Patents

Abstract

PURPOSE:To simplify the constitution of a whole controller by controlling the outputs of laser beams from a second light-receiving source in response to the receiving quantity of second laser beams which are received when the emission of first laser beams is stopped. CONSTITUTION:A first light-emitting source which emits the first laser beams 13 and the second light-emitting source which emits the second laser beams 15 are provided. The first laser beams 13 and the second laser beams 15 are injected on an information storage medium and information is stored or read. A discrimination means for discriminating the emission stop state of the first laser beams 13 which are emitted from the first light-emitting source is provided. A control means controls the output value of the laser beams from the second light-emitting source in response to the receiving quantity of the second laser beams 15 which are received when the emission of the first laser beams 13 is in a stop state. Thus, cost can be reduced and the controller can be miniaturized by simplified constitution.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to controlling the output of laser light emitted to an information storage medium in order to store or read information on the information storage medium. This relates to a laser beam 111tll device.

(Prior Art) Optical disks, for example, are widely used as a medium for storing basic information. In addition, in recent years, various types of optical discs have been proposed, including not only a reproduction-only type that only reproduces information, but also a write-once type that allows additional storage only once, and a rewritable type that allows information to be repeatedly stored and erased.

When storing or reading information on such write-once or rewritable optical discs, the optical head emits a storage laser beam and a reading laser beam, and these laser beams Since it may fluctuate depending on changes in the environment such as temperature or changes over time, it is necessary to control the output of the laser light from the optical head so that it is always constant.

FIG. 4 shows a conventional optical head and its peripheral devices, in which an optical head 103 is placed below an optical disk 101. As shown in FIG. Laser light emitted from the semiconductor laser 105 is converted into parallel light by a collimator lens 121 and then provided to a beam splitter 123 . The beam splitter 123 splits the laser light incident from the semiconductor laser 105 into two directions between the lens 124 and the objective lens 125 . Here, the semiconductor laser 105 is a so-called multi-beam semiconductor laser that includes a light emitting source that emits a laser beam for storing information on the optical disk 101 and a light emitting source that emits a laser beam for reading information. Both laser beams are split into two directions between the lens 124 and the objective lens 125. The laser beam focused by the objective lens 125 is reflected off the storage layer 101a of the optical disk 101, passes through the objective lens 125 again, and is split into two directions between the collimator lens 121 and the detection lens 129 by the beam splitter 123. The laser beam that has passed through the detection lens 129 is applied to a photodetector 131, where it is converted into an electrical signal so that an information signal can be extracted.

By the way, a part of the light reflected from the optical disk 101 enters the photodetector inside the semiconductor laser 105, and the semiconductor laser is affected by this incident light! The laser beam output from J' 105 becomes unstable.

Therefore, a part of the laser light emitted from the semiconductor laser 105 is passed through the lens 124 to the photodetector 126.
The output of the laser beam from the semiconductor laser 105 is controlled according to this detection signal, so-called front auto power control (front Δ, P, C).

(Problem to be Solved by the Invention) However, the conventional optical head shown in FIG.
3, and both of the separated laser beams are adjusted by a lens 124. That is, the two-segment photodetector 126 has a detection section for detecting the laser beam for storage and a detection section for detecting the laser beam for reading. The light is focused and irradiated onto the corresponding detection section. Therefore, the focal length of the lens 124 is 30~
Approximately 50 m1 was required, making it difficult to downsize the device. Furthermore, it has been desired to reduce costs through a simple configuration.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a laser preemption 'a8i@ with a simplified configuration that allows for cost reduction and miniaturization of the device.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a laser beam control device that emits a first laser beam for storing or erasing information on an information storage medium. a first light emitting source that emits light; a second light emitting source that emits a second laser beam for reading information to the information storage medium; and a state in which the laser light of the first light source stops emitting light. a discriminating means for discriminating, and an output value of the laser beam from the second light emitting source according to the amount of the second laser beam received when the emission of the first laser beam is stopped. and a control means for controlling.

(Function) The present invention includes a first light source that emits a first laser beam, and a second light source that emits a second laser beam,
The first laser beam and the second laser beam are emitted onto the information storage medium to store or read information. The device also includes a determining means for determining whether the first laser beam emitted from the first light source is in a stopped state, and when the first laser beam is not emitted, the light is received. The control means controls the output value of the laser light from the second light emitting source according to the amount of the second laser light received.

In this way, the so-called automatic operation is performed according to the amount of the second laser beam received when the first laser beam, which has a larger optical output than the second laser beam, is stopped emitting light. Since the power control (A, P, C) is performed, the output of the laser beam can be easily and appropriately controlled.

(Embodiment) An embodiment of the present invention will be described in detail below with reference to the drawings.

First, the configuration will be explained with reference to FIG.

The optical disc 1 includes a storage layer 1a in which information is stored, and an f-isk substrate 1b made of a transparent material such as glass or polycarbonate. ° Also, the memory 11J of optical disk 1
Tracks 11a are formed as guide grooves at intervals of 1.6 μm, and a large number of oval hole-shaped bits serving as data information are formed on these tracks.

An optical head 3 is arranged below the optical disc 1. This optical head 3 has a semiconductor laser 5. As shown in FIG. 2, this semiconductor laser 5 has a semiconductor laser element 11 which is a first light emitting source and a semiconductor laser element 12 which is a second light emitting source. Semiconductor laser element 11
emits write/erase light 13, which is a first laser light for storing or erasing information, forward, and emits laser light 14 backward.

Further, the semiconductor laser element 12 emits read light 15, which is a second laser light for reading information, toward the front, and also emits laser light 16 toward the rear.

The intensity of the read light 15, that is, the light output, is set to a value lower than the light output of the write/erase light 13. A photodetector 1 is located behind the semiconductor laser element 11.
7 is provided to detect the laser beam 14 emitted backward. Also, laser light 16 from the semiconductor laser element 12
A light shielding plate 18 is provided to shield the light from the laser beam 16, so that the photodetector 17 can reliably detect the laser beam 14 without being affected by the laser beam 16. Further, when the photodetector 17 detects the laser beam 14, it converts it into an electric signal, and sends this converted detection signal to the terminal 19.
Output via. This terminal 19 is A, P, and C which will be described later.
, and a control circuit, and is configured to control the output of laser light from the semiconductor laser element 11 according to a detection signal from the photodetector 17.

The laser light emitted from the semiconductor laser 5, that is, the write/erase light 13 and the read light 15, is converted into parallel light by the collimator lens 21 and sent to the beam splitter 2.
given to 3. The beam splitter 23 splits the laser light incident from the semiconductor laser 5 into two directions between the objective lens 25 and the photodetector 27 .

The photodetector 27 is placed close to the beam splitter 23 and detects the laser beam from the semiconductor laser 5. In other words, the laser beam from the semiconductor laser 5 is transmitted to the photodetector 27 without using a special lens for condensing the light.
can be easily detected by

The laser beam focused by the objective lens 25 is reflected by the storage HA 1 a of the optical disk 1 and is reflected by the objective lens 2 again.
5 and is split into two directions between the collimator lens 21 and the detection lens 29 by the beam splitter 23.

The laser beam transmitted through the detection lens 29 is applied to a photodetector 31. The photodetector 31 converts the received laser light into an electrical signal. Information signals such as data information can be extracted based on the detection signal converted into an electrical signal.

Next, the configuration of the semiconductor laser 5 and its peripheral circuitry will be explained with reference to FIG.

A control unit (CPU) 51 controls the write/erase light 13 emitted from the semiconductor laser element 11 and the semiconductor laser element 1.
Each automatic power control of the read light 15 emitted from 2 (A, P.

In addition to performing the control related to C), it also performs vItll related to emitting or stopping the light emission of the write/erase light 13 when storing or erasing information on the optical disc 1.

The switch 53 has fixed contacts 53a, 53b and a movable contact 5.
3C, and the movable contact 53C is connected to the CPLJ51. One fixed contact 53a is connected to a hold circuit 55 and an auto power control circuit (hereinafter abbreviated as APC circuit) 63, and the other fixed contact 53b is connected to an APC circuit 57. This switch 53 is a CPLI
It is switched according to the control of 51. Specifically, in a state where both the write/erase light 13 and the read light 15 are emitted, the movable contact 53C is not switched to the fixed contact 53a side. Furthermore, when the write/erase light 13 stops emitting light, that is, when only the read light 15 is emitted, the movable contact 53C does not switch to the fixed contact 53b side. Therefore, write/erase light 13 and read light 15
When both laser beams are emitted, CPU5
i is written/written via the switch 53 and the APC circuit 63.
It is connected to an erase light laser drive circuit (hereinafter simply referred to as a drive circuit) 61. The CPU 51 determines whether or not the light emission of the write/erase light 13, which is the first laser light emitted from the semiconductor laser device 11, which is the first light emission mode, is based on the control results regarding the operation of the semiconductor laser device 11. It has a function as a determination means.

The APC circuit 57 is connected to the photodetector 27 and also to a read light laser drive circuit (hereinafter simply referred to as a drive circuit) 59.

This APC circuit 57 outputs the first laser beam 1-/
By controlling the drive circuit 59 according to the amount of read light 15, which is the second laser light, received when the erase light 13 is stopped emitting, that is, the detection signal from the photodetector 27, This is a control means for controlling the output value of the laser light from the semiconductor laser element 12 which is the source of the laser beam.

The drive circuit 59 is connected to the semiconductor laser element 12. This drive circuit 59 drives the semiconductor laser element 12 in accordance with the value of the control signal output from the APC circuit 57 when the semiconductor laser element 11 is in a state where the emission of the write/erase light 13 is stopped. Further, the drive circuit 59 is connected to the hold circuit 55, and the APC circuit 59 is connected to the hold circuit 55.
The value of the control signal input from 7 is output to the hold circuit 55. The bold circuit 55 holds the value of the signal input from the drive circuit 59 while the write/erase light 13 is generated from the semiconductor laser element 11.

The APC circuit 63 is connected to the photodetector 17 and also to the drive circuit 61. This APC circuit 6
3 controls the drive circuit 61 according to the detection signal from the photodetector 17.

The drive circuit 61 is connected to the semiconductor laser element 11 and drives the semiconductor laser element 11 in accordance with a control command from the APC circuit 63.

Next, the operation of this embodiment will be explained.

The CPU 51 controls the emission timing and emission stop timing of the write/erase light 13 emitted from the semiconductor laser element 11 via the switch 53, the APC circuit 63, and the drive circuit 61. The light emission of the write/erase light 13 and the laser light 14 is stopped during the light emission stop period in response to a control command from the controller. Further, the semiconductor laser element 11 is controlled by the drive circuit 6 under control from the APC circuit 63 only during the light emission period.
Write/erase light 13 and laser light 14 are emitted in response to signals from 1. This write/erase light 13 is irradiated onto the optical disc 1 via a collimator lens 21, a beam splitter 23, and an objective lens 25. At this time, information is stored or erased in the storage 111a of the optical disc 1.

On the other hand, the read light 15 is constantly emitted from the semiconductor laser element 12, and this read light 15 is transmitted through the collimator lens 2.
1. The light is irradiated onto the optical disc 1 via the beam splitter 23 and the objective lens 25.

The read light reflected from the storage layer 1a of the optical disk 1 and modulated is given to the detector 31 via the beam splitter 23 and the detection lens 29, where the detector 31 converts it into an electrical signal and reads the data information of the storage layer 1a. I'm trying to take it out.

Next, during the light emission stop period in which the light emission of the write/erase light 13 having a larger light output than the light output of the read light 15 is stopped, the movable contact 53c of the switch 53 is connected to the fixed contact 53.
Switching to the b side, the APC circuit 57 operates. The APC circuit 57 controls the drive circuit 59 in response to a detection signal from the photodetector 27 that detects the read light 15 having a small optical output. In other words, the PC circuit 57 controls the five drive circuits according to the amount of read light 15 received when the write/erase light 13 that produces a large optical output is stopped. , semiconductor laser device 12
control the output value of the laser light from the

Next, when the write/erase light 13 starts to emit light, the bold circuit 55 is connected to the △PC circuit 5 during this light emitting period.
According to the signal value held by the hold circuit 57, the drive circuit 59 is operated to drive the semiconductor laser element 12.

In the above embodiment, the semiconductor laser element 12 as the first light emitting source is configured to emit a laser beam for storing information and a laser beam for erasing information, but the present invention is not limited to this. a semiconductor laser element that emits a laser beam for information storage as a first light emitting source without being
A semiconductor element that emits a laser beam for erasing information may be provided separately and independently. Furthermore, it goes without saying that in place of the photodetector 27, a photodetector built into the semiconductor laser 5 and provided behind the semiconductor laser element 12 may be used.

[Effects of the Invention] As explained above, according to the present invention, with a simple configuration, the second laser beam received when the first laser beam emission is stopped.
Since the output of the laser light from the second light emitting source can be controlled according to the amount of laser light received by the second light emitting source, the configuration of the entire device can be simplified, and the cost and size can be reduced. can.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment according to the present invention, and FIG.
FIG. 3 is a block diagram showing the semiconductor laser 1A and its peripheral circuitry, and FIG. 4 is a configuration diagram showing a conventional example. 1... Optical disk 5... Semiconductor laser 11.12... Semiconductor laser element 17.27... Photodetector 31... Detector 51... CPU 55... Hold circuit 57.63... PC circuit

Claims (1)

[Scope of Claims] A first light emitting source that emits a first laser beam for storing or erasing information on an information storage medium, and a second laser for reading information on the information storage medium. a second light emitting source that emits light; a determining means that determines whether the first laser light is in a stopped state; and a second light emitting source that emits light; A laser beam control device comprising: control means for controlling the output value of the laser beam from the second light emitting source according to the amount of the second laser beam received.