反射式液晶背投影顯示器之色差檢測

The inspection of Chromatic focal shit in LCoS Rear Projection Display

謝順達(Shun-Ta Hsieh)

指導教授 ： 章明

中原大學/工學院/機械工程研究所/碩士(2005年)

https://doi.org/10.6840/cycu200500349

摘要

本研究使用CCD擷取投影影像，利用影像對焦的特性及機器視覺技術，量測反射式液晶背投影顯示器R、G、B三焦點的相對位置。不同波長的光在進入鏡頭後，由於行徑的速度不一樣，以至於最後成像的位置無法匯聚於一點，使影像模糊不清而降低了影像的品質。為了改善影像品質，我們必須先知道投影機中R、G、B三個波長對應的焦點位置，再以適當方式將其調整於相同位置。實測實驗中，本研究使用了五種演算法辨別R、G、B三焦點位置，並以實驗驗證最大梯度值法為最佳演算法。我們針對同一批生產的五顆投影鏡頭進行量測並取平均值，其量測實驗結果顯示B光相對G光的焦點位置為12μm，而R光相對G光的焦點位置為9μm，因此我們可以調整液晶投影顯示器中B Panel跟R Panel的位置，使R、G、B三焦點位置匯聚在同一點上，即可消除色差而得以改善影像品質。

關鍵字

影像檢測 ； 色差 ； 反射式液晶背投影顯示器

並列摘要

This research used CCD to grab the image from a LCoS rear projection display system, and utilizing the characteristic of focal image via machine vision techniques to measure the positions of the three focal points of the RGB lights in the system. In general the image of a projected picture is not easy to converge on the same position due to the speed of the light with different wavelength being different. It makes the image blurred and reduces the quality of the picture. For improving the quality of image, the positions of the three focal points of RGB must be detected first and then adjusted to be coincided each other.
Five kinds of algorithms had been used to distinguish the positions of RGB’s focal popints, and proved with experiments that the Gradient-Magnitude-Maximization has the best performance. Here the measurements were implemented with five projection lens and the mean of the measured values were adopted. Experimental results show that the relative position of focal point of B light to G light is 12μm and the R light to G light is 9μm. Based on the measured data, we can adjust the positions of B Panel and R Panel in LCos, and makes the three focus of RGB lights assembled with the same point. So that the chromatic focal shift can be eliminated and the image quality can be improved.

並列關鍵字

chromatic focal shift. ； Image inspection ； LCoS projector

參考文獻

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