JPS58189849A - Adjusting device of semiconductor laser - Google Patents

Abstract

PURPOSE:To adjust an output level of laser light to a desired value without damaging a semiconductor laser, by limiting the output level of the laser light so as not to exceed a prescribed value, and preventing in advance the semiconductor laser from being driven at a value being the maximum rating or over in advance. CONSTITUTION:The laser light of a diode laser D1 is irradiated on a photodetector 17 via an objective lens 15 and a variable resistor VR1 is operated so that the level of a slide piece is increased, then an output level of the photodetector 17 is increased gradually. When the output level of the photodetector 17 is increased more than the voltage level of the slide piece of a variable resistor VR2, the output of an operational amplifier 21 goes from a low to a high level. The output signal of the operational amplifier 21 is held at a holding circuit 22 and an output inhibiting terminal INH is brought to high level, then the output inhibiting state of an operational amplifier 13 is held. As a result, the laser diode D1 is not excited and damaged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in an adjustment device for a semiconductor radar used, for example, in an optical digital disc player.

[Technical background of the invention]

Recently, for the purpose of recording and reproducing audio signals and image signals with the highest possible fidelity and high density, information signals have been converted to PCM (/'?Russ code monolithic). Digitally encoded signals are recorded directly onto the disc, and optical binoculars are used during playback. An optical raster has been developed to extract and demodulate the digitally encoded signal Jlj' from the disk.In other words, this device is capable of extracting information on one side of the disk. The digitally encoded signal converted into tPCM is directly recorded as a focus train with different intervals between the on and off waves of the concave and convex portions. I am trying to irradiate the formula pickano/garashi-light guide.Then,
This radar light hits the bit string, is reflected, and is received by the pink amplifier. For this reason, an optical pickup detects the intensity and time of the light, and extracts the digitally encoded signal recorded on the disc.

Incidentally, in the optical digital disc player as described above, one of the important things is to adjust the output of the radar light to a predetermined level in advance. In other words, this is to compensate for the r-in fluctuations of the pit detection threshold, focus control system, and tracking control system when the optical pink amplifier is replaced. The output pi of such a laser beam is the same as that of an optical BIC AR! using a conventional semiconductor laser. In the case of , the example is implemented as shown in FIG.

That is, the laser diode D1, which is mounted on the optical pick-up array fJ1 and serves as a semiconductor laser, is the operational amplifier of the drive device 12! It is driven by 13 outputs. The laser light output from this radar diode D is also irradiated to a photodiode DE2 in the optical pinocquat 7'JJ. The current flowing through the photodiode D2 is converted into a voltage via the current-voltage conversion circuit 14f of the drive device 12, and is input to the non-inverting input terminal of the operational amplifier 13, and is then converted into a reference voltage obtained by the single source l and the variable resistor VR. It is something that is compared. Thereby, the radar diode D1 can compensate for changes in laser light output caused by temperature changes at the junction and maintain the laser light output at a constant level.

The laser light from such a laser diode D1 is provided in the optical system 11 and guided as shown by the arrow in the figure through the objective lens IS>. This objective lens 1
In the operation of an optical digital disc player, for example, the Raded light transmitted through 5 is irradiated onto a single force surface of the disc rotated by the disc drive mechanism, but the output level of the Raded light is When adjusting the light, the light is irradiated onto the light receiving section 17 of the level detection device 16, which is separate from the optical digital disc player. This light receiving section 17 is
It is positioned approximately at the focal point of the objective lens 15, and its output is supplied to a display 18, which displays the output level of the radar light.

In other words, the output level of the laser diode D demon's LED light can be determined by checking the output level of the variable resistor VR while referring to the display on the display 18.
i is adjusted to reach a predetermined level.

In addition, there is a beam sinter that transmits the radar light of the optical type big array f11#'i, for example a laser diode D (not shown), and provides the light receiver with reflected light reflected by a disk (not shown), and a plurality of light receivers as the light receiver. It has a photodetector consisting of a light-receiving element.

[Problems with background contact]

However, in such a conventional adjustment method, when adjusting the variable resistor VR, the laser diode Dl is erroneously adjusted.
It is likely that damage will occur if the device is driven beyond its maximum rating. Furthermore, as is well known, semiconductor radars such as radar diodes are extremely expensive, and there is a problem in that it would be a heavy economic burden to replace them every time they are damaged.

[Purpose of the invention]

This invention was made in view of the above points, and it limits the output level of the radar light output from the semiconductor laser so that it does not exceed a predetermined value, and prevents the semiconductor laser from being driven at more than the maximum rating. An object of the present invention is to provide a good semiconductor laser adjustment device that can adjust the output level of a laser beam to a desired value without damaging the semiconductor laser.

[Summary of the invention]

The present invention provides an optical digital disc player for reading out digital encoded signals by irradiating laser light from a semiconductor laser onto a disc on which a digital encoded signal for encoding an information signal is recorded. A driving device that drives the laser so that the output level of the laser beam is constant; a detection device that biases a light receiving section that can irradiate the laser beam with the laser beam; and a display that displays the output level of the light receiving section. a first means for extracting a signal corresponding to the output of the light receiving section from the level detection device; and a method for detecting that the signal extracted by the first means is at least a reference level preset to a desired value. The present invention is characterized in that it comprises a second means for limiting the output of the drive device based on the detection output of the second means.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIG. 7i]1.

FIG. 2 shows the p! ! ! This shows the configuration of the device. However, parts in FIG. 2 that are the same as those in FIG. WJ3 are given the same reference numerals and their explanations will be omitted.

That is, in the level detection device 16, the light receiving section 1
The connection midpoint of 7 and 7iz@';jlB is the terminal T
k Intermediate L-operan 7'2J that constitutes the level comparator
The non-inverting input terminal of is connected to δ. This o(An!2)
) has the oJ dynamic intercept of the variable resistor VR, connected to its inverting input terminal. This variable resistor VR has one end grounded and the other end connected to the anode of the power supply V. This power supply v
The anode of No. 8 is connected to ground.

- Power, front 1 O (Although omitted in the above explanation, Ang 13 has an output inhibit terminal INH'i, and output is inhibited when this output inhibit terminal INH changes from low level to high level!) Like 1-). The output terminal of the operational amplifier 2 is connected to the output inhibit terminal INH of the operational amplifier 13 via a holding circuit 22.

That is, in the device configured as above, the voltage level of the movable intercept of the variable resistor VR, for example, is higher than the received light sJ7 output when the Raded light output level of the Raded diode DI matches the desired value. v'-? ＝ shall be set in advance so that

As a result, the laser beam of the diode D+ is irradiated to the light receiving section 17 via the sound objective lens 151, and the variable resistor VR
When the movable intercept level is increased to +', the output level of the light receiving section 11 increases as desired. When the output level of the light receiving section 17 becomes larger than the voltage level of the movable intercept of the variable resistor vR1, the operational amplifier 21
d. Change the output from low level to high level. The output signal of the operating horn is held in the holding circuit 22 and is brought to the output inhibiting terminal INHk level to maintain the output inhibited state of the operating horn 3. As a result, the radar diode D1 is not excited and is not damaged.

In addition, the variable resistor VR was operated again to lower the voltage level of its movable section, and the holding circuit 2 was removed by means not shown.
2f reset threshold, variable resistor VR as described above.
, it is possible to readjust the output level of the laser light of the laser diode D.

It should be noted that the present invention is not limited to the above embodiments, but may be configured as described below.

For example, the output of op amp f13 is on/off b]*? * to the radar diode D+ through a meeting circuit.
You may pay.

In addition, the laser diode D is connected to the laser diode D via a limiter circuit that is turned on when the output terminal level of the operational amplifier 21 is equal to 0.
lk drive is very popular.

Other various ○ transformations -? It goes without saying that the present invention can be applied without departing from the gist of the present invention.)

〔Effect of the invention〕

As described above, according to the present invention, the output level of the radar light output from the semiconductor radar is J'! ? In order to prevent damage to the semiconductor laser, the output level of the laser beam should be adjusted to the desired value. Therefore, it is possible to provide a favorable semiconductor radar adjustment device that can perform the following steps.

[Brief explanation of drawings]

1 shows the factors used to explain the output level setting means of a conventional semiconductor laser, and FIG. 11. Optical pickup, 12... Drive device, 13
...O(An!, 14...Voltage at voltage conversion circuit, 15
...Objective lens, 16 level detection it, z7...
Light receiving unit, 18...Display unit, 21...Opean! , 22・
・Holding circuit, D, ・Raede diode xD1
・Photo/(#-to, VllV, ...power supply, VRl
, VRl...variable resistor.

Claims (1)

[Claims] In an optical digital disc grayer that reads out the digital encoded signal by irradiating a laser beam of a semiconductor laser onto a disk on which a digital encoded signal obtained by encoding an information signal is recorded, a laser beam is applied to the semiconductor laser. a detection device comprising: a driving device for driving the light so that the output level of the light is constant; a light receiving section on which the laser beam of the semiconductor radar is irradiated with the number of colors; and a display device for displaying the output level of the light receiving section; A first means for extracting a signal corresponding to the output of the light receiving section from a level detection device, and a second means for detecting that the signal extracted by the W, 10 means is equal to or higher than a reference level set to a desired value in advance. 2 means and
An adjusting device for a semiconductor radar, comprising: third means for limiting the output of the drive device based on the detection output of the WJ2 means.