本論文提出一組微型投影機的架構。投影機採用L型光路來結合成像與非成像系統。光源選擇發光二極體(Light Emitting Diodes, LEDs)取代傳統燈泡，因為LED具有低耗電量、反應快、體積小、耐震動以及適合量產等優點。投影機之系統光閥為反射式矽基液晶顯示器(Liquid Crystal on Silicon, LCOS)，LCOS屬於色序式(color-sequential)的樣式。 非成像系統只用一組準直鏡，並採用單片微透鏡陣列(Micro-lens Array, MLA)來達成面板上光強度均勻化的目的。單片微透鏡陣列為雙面同曲率，微透鏡大小為320 μm × 180 μm，此種設計可以讓面板上之照度均勻度達到86%，並且有效地縮小非成像系統的體積。設計完成之非成像尺寸為31 mm × 11 mm × 11 mm。投影鏡頭共使用5片鏡片(2片球面玻璃和3片非球面塑膠)，設計出總長15 mm的定焦鏡頭，此鏡頭在距離50 cm處投射約A4大小的影像，而調製轉換函數(Modulation Transfer Function, MTF)在空間頻率94 lps/mm內所有視場皆大於0.5，光學畸變(Optical distortion)小於1.5%，結合非成像系統與成像系統尺寸為31 mm × 24 mm × 11 mm (不考慮組裝外殼)。非成像系統由外部廠商製作， LCOS面上的光能量分佈出現傾斜，且角度大於10°。LCOS有效面積上的光學效率為22%。 In this thesis, we propose a pico-projector system. The projector including an image system and a non-image system is designed using an L-shape light path. Light emitting diodes (LEDs) are adopted to replace traditional lamps for projectors, because of low-power consumption, quick switch time, small volume and large production. Liquid crystal on silicon (LCOS) panel with color-sequential type is selected for the light valve in the system. The non-image system includes a set collimator, a homogenizer, and a set condenser. The set collimator consists of two sphere glass lenses. A piece of micro-lens array (MLA) is designed for homogenization. The same curvature radius is set for 1st and 2nd surface of a unit micro lens with area of 320 μm × 180 μm. The set condenser consists of two aspheric plastic lenses to distribute light within the LCOS active area. Base on this design, the uniformity on panel can achieve 86% and the system volume effectively reduce to 31 mm × 11 mm × 11 mm. In terms of image system, projection lens consists of two sphere glass lenses and three aspheric plastic lenses. Projection lens is fixed-focus, and its total track is 15 mm. A4-size image is obtained at 50-cm distance. The modulation transfer function (MTF) is larger than 0.5 on all fields within spatial frequency 94 lps/mm. The optical distortion is smaller than 1.5%. The whole size of projector is 31 mm × 24 mm × 11 mm without consideration of outer shell. The finished non-image system performs 22% optical efficiency on LCOS active area; however, light distribution tilts 10° on the LCOS surface degrading the color mix performing on the active area.
