Free stereoscopic display technology can observe the 3D image without wearing glasses or helmet, so it has a great advantage compared with the auxiliary stereoscopic display technology. In addition, the requirements of the free stereoscopic display technology to the device are far lower than the true 3D stereoscopic display technology. Therefore, the researchers and manufacturers have paid much attention to it.
However, the free stereoscopic display technology also has such problems as 2D and 3D display compatibility, resolution and view number, natural 3D display, and 3D image touch control. Therefore, researchers and manufacturers are constantly looking for technical solutions to improve the display effect of the free stereoscopic display technology in these four aspects.
2D and 3D display compatibility
As the current 3D display content (such as movies) is limited, consumers want 3D TV to be able to integrate the 2D display capabilities. For the existing autostereoscopic display technology, though the 2D display can be achieved by displaying the odd and even number pixels of the display panel, but each eye can see only part of the pixels of the display panel, so the resolution of 2D image is greatly reduced. In addition, the 2D display will exist fence effect, so that the quality of the 2D image is reduced.
In order to solve the problem of compatibility between 2D and 3D, researchers have put forward various methods, in which widely used parallax baffle and microcolumn lens are replaced by switchable liquid crystal layers. The switchable liquid crystal layer is composed of a liquid crystal layer and a transparent electrode plate on both sides of the liquid crystal layer. The electrode pattern on the transparent electrode can be designed according to the arrangement of the liquid crystal. The working principle of the switchable liquid crystal layer is shown in Figure 4. When no voltage is applied on a transparent electrode,
As shown in Figure 4 (a), the liquid crystal layer can transmit light through the LCD panel normally, so the display works in the 2D mode. When the voltage is applied on the transparent electrode plate,
As shown in Figure 4 (b), factor in the liquid crystal layer can be arranged in the shape of the lens, and the formation of micro cylindrical lens array, which can be left / right eye image pixel light guide are left eye / right eye, the display device in 3D mode; when the voltage applied to the transparent electrode plate, liquid crystal molecules the liquid crystal layer can also be arranged.
As shown in Figure 4 (c), the parallax barrier can make the left eye / right eye receive only the light emitted from the left eye / right eye image pixels, and then achieve the 3D display function. In order to further enhance the control ability of pixel edge liquid crystal molecules, avoid the crosstalk of left and right eye images and the deterioration of 3D image quality, Huang et al. Introduced several electrodes for each column pixel, thus enhancing the control ability and image quality of liquid crystal molecules.
In order to maintain the arrangement of the liquid crystal molecules in the 3D mode, the voltage of the liquid crystal layer needs to be applied continuously, and then the power consumption in the 3D mode is increased. ZHANG et al. Proposed a liquid crystal light valve incorporated into the gel factor. The operating principle of the liquid crystal light valve is shown in Figure 5.
The liquid crystal layer is heated to the temperature of liquid crystal clear temperatures above; then applying voltage to the liquid crystal layer and the liquid crystal molecules arranged in a desired shape; and then cooling the liquid crystal layer, the temperature dropped, the gel factor can according to the arrangement of liquid crystal molecules form a self-assembled structure; finally, under voltage, the self the assembly structure can maintain the liquid crystal molecules no voltage is applied to the case of arrangement. Therefore, the power consumption of the display unit in the 3D mode can be reduced.