Multiple-LED color-sequential liquid crystal on silicon projector

Abstract

In this thesis, a multiple-LED color-sequential Liquid Crystal on Silicon (LCOS) projector is presented. The main reason of designing this kind of projector is the market need for small, high-quality projectors and also integrated solutions for mobile devices like cellular phones and mobile game consoles. Low power consumption of the driving electronic subsystem and high efficiency of the optics subsystem are two important features of this kind of mini-projectors. A specific electronic subsystem was designed to drive this field sequential color LCOS panel with low power consumption. An optics subsystem for projection was developed to improve the optical efficiency of the projector. Conventional color projectors use color wheels to split red, green, and blue (RGB) light from white light to give color projection. With the fast development of LED technology, RGB LEDs can be turned on in the right sequence to make color projection possible. In this thesis, I firstly developed an electronic subsystem to drive the LCOS panel in RGB sequence. I further added a white subframe and developed a RGBW color sequence to boost the brightness. The RGBW color sequence running at 240 Hz could improve the brightness vastly, compared with the results obtained from the 180 Hz RGB color sequence. An optics subsystem is designed to direct the LED light onto the small LCOS panel. Flower-shaped compound parabolic concentrator (CPC) is chosen from several designs for a compromise between performance and size. The custom-designed CPC presents an efficiency of up to 90%. Moreover, 54% of light could fall into F/2.0 of the projection lens. A 0.59-inch diagonal LCOS panel with an SVGA resolution of 800x600 pixel and 180 lumens RGB LEDs are used to implement this field sequential color projector. A brightness of 6 lumens is achieved.