Power System For Laser Diode In The Laser Projector

Laser display technology with high purity, wide color gamut has become thedevelopment trend in the display industry, and laser projector industry is the focus of displayproducts at home and abroad. Laser diode as the the most commonly used light source of laserprojector what the stability of injection current and working temperature has a direct andobvious influence on the output of it and also influent the projecting effect of laser projector.Hence it has a very important significance for laser projector to design a power system whichwith the stable driving current and precise controlling temperature.This paper starts with the principle of laser diode and study on its characteristics,analyzes the main reasons for the effects of laser diode constant output and the requiredtechnical qualifications for the laser diode driving source. Based on these technicalqualifications and the objective needs of the projector, puts forward a design scheme for laserdiode driving source based on laser projector. The whole system is composed of laser currentdriving module and temperature control module. The laser driving module adopts the designidea of switch power supply, uses of automatic current control design concept and achievesthe steady control of laser injection current. Meanwhile, the laser driver module also includesthe design of optical power detection which feedbacks for optical power to realize the stableoptical power control. The temperature control module, which is based on the automatictemperature control theory, uses the control method of proportion-integral-differential,controls the cooling and heating capacity of thermoelectric cooler, and achieves the precisetemperature control of a low-power laser diode for high-power laser projector.In addition, aiming at the shortcomings of laser diode what include the fragility itself anda variety of security risks in the process of using, protections circuits are designed. Theseprotection circuits include ESD protection circuitry, slow-start circuit, under-voltageprotection circuit, over-voltage protection circuit and alarm circuit etc. Finally, the performance tests of this prototype of laser driving source system are done.Experiments show that using this system, the stability of the drive current and the precision oftemperature control and other performance has achieved the design goals. Combined withother components, laser projector prototype was successfully developed.