| 摘要: | 本文提出非對稱聚光鏡高效率投影機光路設計包含照明系統與成像系統。在照明系統設計，使用非對稱聚光鏡把LED光源投射至透鏡陣列內，由於透鏡陣列之水平與垂直數值孔徑不同，為了提高投影機光效率，非對稱聚光鏡之水平與垂直數值孔徑設計，必須與透鏡陣列之水平與垂直數值孔徑相同。在DMD照明區域必須考量照明系統之過溢量設計，而透鏡陣列出射光線會經由Relay lens投射至DMD上所設定的照明區域。由於DMD輸出有On、Flat、Off三種狀態，我們使用TIR稜鏡組可使On狀態光源入射於投影鏡頭。
在成像系統設計，所要投射螢幕對角線為60、DMD有效區對角線長度為0.4576，可計算橫向放大率為-131.12倍與投射距離為2.1 m，其有效焦距(EFL)為16.0 mm、F/#為1.8，物像距離為2200 mm。評估投影鏡頭解像能力為在所有視場MTF(66 lp/mm)大於67.3%，橫向色差小於2.13 m，光學畸變小於1.45%，相對照度大於90.98%。
最後整個投影機系統設計尺寸為102.9 mm×99.2 mm×36.0 mm。設各元件表面穿透率為100%，則RGB LED三光源投射在螢幕上的總效率，紅光效率為56.25%、綠光效率為49.57%、藍光效率為46.66%。而在螢幕上均勻度，紅光光源之平均差為1.78%，綠光光源之平均差為2.46%，藍光光源之平均差為1.97%。RGB LED光源投射至螢幕上與NTSC標準色域比較之後的色彩飽和度為95.25%。
;This paper presents a high-efficiency projector optical design with asymmetric condenser includes an illumination system and an imaging system. In the illumination design use the asymmetric condenser to project LED light source into the lens array. Because of the numerical aperture of lens array in horizontal is different numerical aperture of lens array in vertical direction and if we want to improve the light use efficiency, the numerical aperture of lens array and the numerical aperture of asymmetric condenser must be the same. In DMD illumination area must consider the overfill of the lighting system design, then the output of lens array will be projected onto the DMD illumination area by relay lens. According to, there are three different types of DMD output, respectively On-state, Flat-state, Off-state, we need to use the TIR Prism to control the DMD output and make the light will be projected into the projection lens when DMD is On-state.
In the imaging system optical design, the diagonal of the screen is 60 inches, the diagonal of DMD is 0.4576 inches. We can calculate the magnification is -131.12 times and the projection distance is 2.1 meters. And the effective focal length, f/#, total track of the projection lens is respectively 16.0 mm, 1.8, 2200 mm. Then, we assess resolution of the projection lens at all fields, MTF (66 lp/mm) is greater than 67.3%, lateral color is less than 2.13 m, optical distortion is less than 1.45% and the relative illumination is greater than 90.98%.
Finally, dimensions of the entire projection system are 102.9 mm×99.2 mm×36.0 mm. Assume transmittance of all the elements is 100%, the overall efficiency of red LED projected on the screen is 56.25%, green LED is 49.57%, blue LED is 46.66%. Then, we simulate the uniformity of illuminance on the screen, the average deviation of red LED is 1.78%, green LED is 2.46%, blue LED is 1.97%. And we compare the color gamut with NTSC standard, color saturation of RGB LED is 95.25%. |
