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By Sung J. Lee, Min J. Kim, Kyo H. Lee, and Kwang H. Park
One problem with the conventional structure of flat-panel LCD displays is that it limits viewing angles and distances. To remedy that, a Korean company has developed two types of a structured 2D/3D switchable stereoscopic LCD display by changing the structure of the conventional thin-film transistor (TFT) LCD. Multiple viewers can watch a 3D image on this display simultaneously and the company expects it to be used as a 2D/3D switchable LCD panel in the next generation of flat-panel LCDs.
The conventional stereoscopic LCD display has a patterned retarder (Figure 1), in which horizontal strips of half-wave (or quarter-wave) retarders alternates with those of transparent glasses attached to the outer surface of the TFT-LCD. This display requires polarized glasses to view 3D images.
A new structure
The proposed structure for the wire grid polarizer (WGP), which contains rows of alternating polarization angles, can be seen in Figure 2. When a voltage is applied, an incidence light (L1) with a polarization orientation of 45 degrees enters WGP 1, transmits it to the liquid crystal layer before being blocked by WGP 3 which has a polarization orientation of 135 degrees. The incidence light (L2) transmits to WGP 2) and the LC (liquid crystal) layer. After this, it is absorbed by WGP 4, which has a polarization orientation of 45 degrees. Of course, when an electric field for the LC layer is turned off, incidence beams L1 and L2 transmit to WGP 3 and WGP 4, respectively1.
In the case of our proposed structure, WGP 1 and WGP 2 have rows of alternating polarization angles and are affixed to the inner surfaces of the TFT panel and color filter substrates. Therefore, the polarizers are disposed adjacent to the LC layer and the polarizers eliminate the parallax problem.
We designed and fabricated a 5.5 inch VGA (640×RGB×480) resolution-stereoscopic display using WGPs with rows of alternating polarization angles2.