Optical Design Of The DLP Proiection System Based On RGB LED Lighting

As a burgeoning type of modern projection display technology, pico-projection shows the advantages of its miniaturization and portable size. Pico-projection technology has gradually changed people’s daily life and attracted more and more attention within the rapid development of the information age. Nowadays, pico-projection technology is becoming one of the most important development trends of projection display. Digital light processing (DLP) projection display technology has distinct characteristics of high-brightness, high-contrast, high-resolution. With the help of new types of Light Emitting Diode (LED), DLP technology could promote the miniaturization of portable projection and meet the needs of liberalization and portability.This thesis mainly discusses the basic principle of DLP projection display and the design methods for key components of the illumination system. Based on the etendue matching principle, we offer a complete design solution for a portable projection light engine, which could be applied to commercial display or home theater use.Firstly, the illumination principle using a fly-eye integrator is derived based on both the ideal light source and extended source approximation. From this, we could conclude the etendue matching conditions among the LED light source, fly-eye lens and DMD display panel. Considering the difficulty in designing DLP projection optical engine, the thesis presents the LED light collimation design with the application of surface slope Angle control method, which could, get reasonable spot diameter and divergence angle for subsequent fly-eye lens and relay lens system. This design achieves the maximum utilization of the LED light source energy, and more than90%of the LED emitting luminous energy can be used by subsequent system.Considering the design requirements of offset projection, this thesis introduces a non-rotationally symmetry wedge freeform lens into imaging system design. With the help of optical design software CODE V, custom image quality evaluation function is established and the x and y directions on some column point root mean square radius size values could be optimized. Offset projection could be realized without any increase in the size of the lens system. It is believed that the method can provide a novel design thought for future offset type projection lens.Based on the previous design method, a DLP projector is fabricated and measured. The final parameters of the projector are listed as follows:projection resolution of1280X800(WXGA), projection distance ranging from0.5m to3m(15-90inches full offset screen),above300lm light output under the condition of LED power45W,the uniformity of95%.Finally, the tolerance analysis and stray light processing is discussed for the designed projector, which is used to guide mechanical and thermal design. The simulation results could also make the optical design more practical and easier for mass production.