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Semiconductor laser drive circuit and photoelectric sensor

A laser drive and semiconductor technology, which is applied in the direction of semiconductor lasers, semiconductor devices, lasers, etc., can solve the problems of inability to control APC, slow rise of load voltage, etc., and achieve the effect of improving response speed, increasing speed, and realizing drive control

Inactive Publication Date: 2007-10-17
PANASONIC INDAL DEVICES SUNX
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in this circuit, since no reverse voltage is applied to the photodiode 2 for monitoring and a non-biased state is formed, the following disadvantages will occur: even if the photodiode 2 for monitoring receives light, it will not flow immediately to the photodiode 2 for monitoring. The current with a linear relationship to the amount of light received and the load voltage of the resistor 6 connected in parallel with the monitor photodiode 2 rise slowly, and high-speed APC control cannot be performed.

Method used

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  • Semiconductor laser drive circuit and photoelectric sensor
  • Semiconductor laser drive circuit and photoelectric sensor
  • Semiconductor laser drive circuit and photoelectric sensor

Examples

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Embodiment 1

[0026] A first embodiment of the present invention will be described with reference to FIGS. 1 and 2 .

[0027] First, the structure of the photoelectric sensor and the semiconductor laser drive circuit of the present embodiment will be described.

[0028] (1) The overall structure of the photoelectric sensor

[0029] The transmissive photoelectric sensor 10 of this embodiment is oppositely provided with a light projecting part 11 that emits parallel light from a light projecting window 12 with a rectangular slit-shaped opening, and a light-receiving part with a light-receiving window 22 that also opens in a rectangular slit-shaped shape. 21. Set the region R1 (the part surrounded by dotted lines in FIG. 1 ) that can detect the optical path of the light emitted from the light projection window 12 of the light projection part 11 and incident into the light receiving window 22 of the light receiving part 21, Based on the amount of light received by the light receiving unit 21 w...

Embodiment 2

[0046] Fig. 3 shows a second embodiment. The main difference from the above embodiment is that the PNP transistor 40 is used instead of the NPN transistor 32 as the current control element and the structure of the bias device, and other points are the same as the above first embodiment. Therefore, the description of repeating the same reference numerals as those of the first embodiment will be omitted, and only the differences will be described below.

[0047] FIG. 3 shows the structure of the semiconductor laser drive circuit 43 of this embodiment. As shown in this figure, a PNP transistor 40 serving as a current steering element is configured to be connected between the power supply line L1 and the anode of the laser diode 30 . In addition, a resistor 41 and a Zener diode 42 are connected in series between the power line L1 and the ground line G, and the cathodes of the laser diode 30 and the photodiode 31 for monitoring are connected to these connection points. Accordingl...

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Abstract

Provided is a semiconductor laser drive circuit, etc. which can rapidly control with a single power source, in a drive circuit for a semiconductor laser element having a semiconductor laser diode commonly connected through cathodes to each other and a photodiode for monitoring. In the semiconductor laser drive circuit, when a laser diode 30 emits light, current flows to the photodiode 31 for monitoring, and a control signal in response to a voltage level V4 responding to the current and a reference voltage level Vref is applied from a differential amplifier 34 to an NPN transistor 32 to be operated on. Also, a reverse bias voltage is applied to the photodiode 31 for monitoring. Thus, a high speed APC control by the single power supply can be performed.

Description

technical field [0001] The invention relates to a semiconductor laser driving circuit and a photoelectric sensor. Background technique [0002] For example, a so-called transmissive photoelectric sensor has a structure that has a light emitting element and a light receiving element facing each other, and based on a change in the amount of light received in the light receiving element, detects the presence of the object or measures the position and size, etc. , the light receiving element changes according to the light shielding state of an object existing in the optical path of the laser beam irradiated from the light projecting element to the light receiving element. In order to stably perform detection in such a photoelectric sensor, it is necessary to keep the output of laser light from the light projecting element constant. [0003] Therefore, conventionally there is a semiconductor laser drive circuit that controls the drive of the light projecting element by APC (Auto...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01S5/0683G01V8/12H01L31/12H01S3/00H01S5/042
CPCH01S5/0683
Inventor 落合隆幸竹田隆行
Owner PANASONIC INDAL DEVICES SUNX