Lcd Rear Projection Shows The Three-color System Convergence

Projection display has been growing up rapidly in the 1990's. For the advantages of large screen, high output luminance, and high quality of the projective image, it is playing more and more important role in lots of fields. Among these technologies, the projection display is the most practical one, because of its lowest cost and most convenient to use.Projection display for large screen has a high requirement for the projected images that should be sharp, vivid, and with high quality. In three- panel projection system, the panels must be adjusted precisely to proper position in order to achieve the satisfied images., What's more, the correspondent pixels on three panels in R,G and B colorlight must be overlapped exactly.In the thesis, we first introduce the actuality and development of the display industry. Three kinds of present projection display techniques have been discussed: LCD projection display, DLP (Digital Light Processor) projection display and LCOS (Liquid Crystal on Silicon) projection display, especially the advantages and disadvantages of color combination techniques.Second, the thesis introduces the hardware and its function in the three colors' automatic focusing and automatic alignment system.Based on the nature of the projection display, a mathematical model has been developed to realize the accurate focusing and accurate alignment by using the digital image processing technology and the computer control technology. The model includes automatic focusing and automatic alignment.Based on the adjusting model, the three colors' automatic focusing and automatic alignment is realized on the platform of the large screen rear projection display system. After getting the variance method to evaluate the quality of the focusing, some special methods to reduce the focusing evaluation time are proposed. The thesis analyzes Pixel's facula center algorithms for the automatic alignment. After comparing these algorithms, the gravity center algorithm in this system for its good stability and goodadjustment result under noise background is choosed. The thesis also analyzes several methods in automatic alignment, and got CCD symmetry method for its good stability and accuracy.Finally, the conclusion and future research direction are given.