JPH0191343A - Output control method for semiconductor laser of multibeam magneto-optical pickup - Google Patents

Abstract

PURPOSE:To enable the erasur, the recording and the reproduction of high speed by detecting emitted beams from a semiconductor laser for erasing and recording and a laser for reproducing, and controlling drive by comparing them with respective reference voltages in an erasure, a recording and reproduction modes. CONSTITUTION:The emitted laser beams of the reproducing semiconductor laser 13 and the erasing semiconductor laser 12 are detected by a photodetector 19. In the erasure mode, at the time of recording an address, the laser 12 is switched off, and the output of the laser 13 is controlled to be a reference value, and in an erasing area, the laser 12 is lit, and its output is controlled to be the reference value. In the recording mode, at the time of the recording of the address and in a recording area, the output of the laser 13 is controlled to be the reference value while the laser 12 is not lit, and the output of the laser 12 is controlled to be the reference value after the read of the address and during a period before it reaches the recording area. In the reproduction mode, the output of the laser 13 is controlled to be the reference value. Thus, the erasure, the recording and the reproduction of high speed can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a semiconductor laser output control method for a multi-beam magneto-optical pickup.

(Prior Art) Writing of information to a magneto-optical disk is completed in three modes: erasing, recording, and reproduction. If this is done with a magneto-optical pickup having one semiconductor laser, the same location on the magneto-optical disk must be traced three times with a laser beam, which is very time consuming. Therefore, high-speed erasing,
The use of a magneto-optical pickup having a plurality of magneto-optical pickups or a plurality of semiconductor lasers for recording and reproduction has been proposed in Japanese Patent Application Laid-Open No. 60-47238, etc.; It is necessary to control each output to a predetermined reference value.

(Objective) In view of the above points, an object of the present invention is to provide a semiconductor laser output control method for a multi-beam magneto-optical pickup that can control the output of a plurality of semiconductor lasers.

(Structure) The present invention provides a magneto-optical pickup having a semiconductor laser array in which a first semiconductor laser for erasing and recording and a second semiconductor laser for reproducing are arranged side by side. Turn off the laser and
The output of the semiconductor laser is controlled and held at a reference value, the output of the first semiconductor laser is controlled to be the reference value by lighting the first and second semiconductor lasers in the erase area, and the output of the first semiconductor laser is controlled to the reference value in the recording mode. During reading and when the first semiconductor laser is not lit in the recording area, the output of the second semiconductor laser is controlled and held at the reference value, and the output of the second semiconductor laser is controlled and held at the reference value until the laser beam reaches the recording area after reading the address. During the period, the first semiconductor laser is turned on, and with the first and second semiconductor lasers turned on, the output of the first semiconductor laser is controlled and held at the reference value, and in the reproduction mode, the second semiconductor laser is turned on. Control the laser output to a reference value.

The present invention will be described in detail below with reference to the drawings.

FIG. 3 shows an example of a magneto-optical pickup.

The semiconductor laser array 11 includes two semiconductor lasers 12°1
The two semiconductor lasers 12 and 13 emit laser beams in substantially the same direction. The laser beam emitted forward from the semiconductor lasers 12 and 13 is transmitted through a coupling lens 14.
and is reflected by the beam splitter 15.

The objective lens 16 illuminates the magneto-optical disk 17 as small spots Sl and S2. Semiconductor laser 12
is used for erasing and recording, and the semiconductor laser 13 is used for reproducing, and the interval between the spots Sl and S2 is, for example, 50 μm. Each laser beam reflected by the magneto-optical disk 17 is detected by a detection system via an objective lens 16 and a beam splitter 15.

Further, a magnetic field is applied to the magneto-optical disk 17 by a magnetic head 18, and the magneto-optical pickup including the magnetic head 18 and the above-mentioned optical system moves in the radial direction of the magneto-optical disk 17, and the magneto-optical disk 17 rotates. Information on the disk 17 is erased, recorded, and reproduced.

FIG. 1 shows an example of an apparatus used to carry out the present invention. This device controls the output of the semiconductor lasers 12 and 13, and the laser beam emitted backward from the semiconductor lasers 12 and 13 is detected by a photodetector 19 consisting of one photodiode and amplified by an amplifier 20. be done. The output of this amplifier 20 is converted to a reference voltage Vre by comparators 21 and 22.
It is compared with f 1 and Vref 2, and the error outputs are sampled and held by the timing signals TI and T2 from the timing generation circuit 27 in sampling and holding circuits 25 and 26 through low-pass filters 23 and 24, respectively. The semiconductor laser drive circuits 28 and 29 control the drive currents of the semiconductor lasers 12 and 13 using the output signals of the sampling and hold circuits 25 and 26, and control the drive currents of the semiconductor lasers 12 and 13.
The optical outputs 2 and 13 are always at the reference voltage Vrefl.

It is controlled to a value corresponding to Vref2. Further, a semiconductor laser drive circuit 28 turns on/off the semiconductor laser 12 by modulation input.

Next, this device will be explained according to the operating state shown in FIG. 2(a).

The reproducing semiconductor laser 13 is always lit in any state. Semiconductor laser 12 for erasing and recording during standby
is turned off, and only the output of the semiconductor laser 13 is incident on the photodiode 19. At this time, the timing signal T2 is at a high level, and the output of the semiconductor laser 13 is controlled to be equal to the reference voltage Vref2.

In the erase mode, the timing signal T2 goes to a high level when reading an address, as shown in FIG. The output of the semiconductor laser 13 is controlled to a value corresponding to the base Kl pressure Vref2. The semiconductor laser drive circuit 28 turns on the semiconductor laser 12 in the erase area and turns it off in the address reading area by modulating input as shown in FIG. 2(C). As shown in FIG. 2(D), the output of the low-pass filter 23 is sampled by the sampling hold circuit 25 when the timing signal T1 is at a high level, as shown in FIG. 25, and the output of the semiconductor laser 12 is controlled to a value corresponding to the reference voltage Vref1. Since the semiconductor laser 13 is on when controlling the output of the semiconductor laser 12, an input signal corresponding to the combined output of the two semiconductor lasers 12 and 13 is input to the comparators 21 and 22. 13 is controlled to be constant, the reference voltage Vrefl may be set in advance to a value obtained by adding the reference voltage Vref2 to a predetermined value. Both semiconductor lasers 12 and 13 are turned on during erasing to confirm erasure of information.

In the recording mode, the output control of the semiconductor laser 13 is the same when reading an address as when erasing. In the recording area, when the semiconductor laser 12 is not in the lighting state, that is, when information is not being recorded, the timing signal T2 is at a high level, and when the semiconductor laser 12 is in the lighting state, the timing signal T2 is at a low level. The sampling and hold circuit 26 samples the output of the low-pass filter 24 when the timing signal T2 is at a high level, holds the value when the timing signal T2 is at a low level, and controls the output of the semiconductor laser 13.The output of the semiconductor laser 13 is controlled by the timing signal T1. As shown in Figure 2 (D), after reading the address, the laser beam of the magneto-optical pickup remains at a high level until it reaches the recording area, and due to the modulation input as shown in Figure 2 (C), the semiconductor laser [2] Lights up.In this case, comparator 21
．． 22 receives an input signal corresponding to a signal obtained by combining the outputs of the two semiconductor lasers 12 and 13. The output of the semiconductor laser 12 is controlled by controlling the output of the semiconductor laser in the same manner as during erasing, and the timing During recording, the signal T1 becomes low level, the sampling hold circuit 25 enters a holding state, and the output of the semiconductor laser 12 is controlled to be constant. In this state, the semiconductor laser 12 is turned on/off by the information signal by the modulation input, and information is recorded on the magneto-optical disk 17.5 In the playback mode, the semiconductor laser 13
The output of the semiconductor laser 12 is controlled and the semiconductor laser 12 is turned off.

(Effects) As described above, according to the present invention, in a magneto-optical pickup having a semiconductor laser array in which a first semiconductor laser for erasing and recording and a second semiconductor laser for reproducing are arranged, it is possible to read an address in the erasing mode. At times, the first semiconductor laser is turned off, the output of the second semiconductor laser is controlled and held at a reference value, and the first and second semiconductor lasers are turned on in the erasing area to control the output of the first semiconductor laser. The output is controlled to a reference value, and in the recording mode, the output of the second semiconductor laser is controlled and held at the reference value when reading an address and when the first semiconductor laser is not lit in the recording area. After reading, the first semiconductor laser is turned on for a period until the laser beam reaches the recording area, and the output of the first semiconductor laser is controlled to a reference value while the first and second semiconductor lasers are turned on. In the playback mode, the output of the second semiconductor laser is controlled to the reference value, so the output of a plurality of semiconductor lasers can be controlled and erased at high speed. Playback becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a device used to implement the present invention, FIG. 2 is a timing chart of an interlayer, and FIG. 3 is a diagram showing an example of a magneto-optical pickup. 12.13... Semiconductor laser, 19... Photodetector,
21, 22... Comparator, 23.24... Low pass filter, 25, 26... Sampling hold circuit,
27... Timing generation circuit, 28.29... Semiconductor laser drive circuit.

Claims (1)

[Claims] In a magneto-optical pickup having a semiconductor laser array in which a first semiconductor laser for erasure recording and a second semiconductor laser for reproduction are arranged side by side, in the erase mode, the first semiconductor laser is turned off when reading an address, and the second semiconductor laser is turned off when reading an address. The output of the semiconductor laser is controlled and held at the reference value, the first and second semiconductor lasers are turned on in the erase area, the output of the first semiconductor laser is controlled to the reference value, and the address is read in the recording mode. The output of the second semiconductor laser is controlled and held at the reference value when the first semiconductor laser is not lit in the recording area, and the period after the address is read until the laser beam reaches the recording area. With the first semiconductor laser turned on and the first and second semiconductor lasers turned on, the output of the first semiconductor laser is controlled and held at a reference value, and in the reproduction mode, the output of the second semiconductor laser is A semiconductor laser output control method for a multi-beam magneto-optical pickup, characterized in that the output of the multi-beam magneto-optical pickup is controlled to a reference value.