Optimal configuration for 3-d lc cell with half-wave retardation using Film Patterned Retarder technology

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KLCC 2005, Vol. 8, pp.1-4

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Optimal configuration for 3-D LC cell with half-wave retardation using Film Patterned Retarder technology

Byung-June Mun, Jeong-Ho Cho and Gi-Dong Lee*

Department of Electronics Engineering, Dong-A University, 2, Busan, 604-714, Korea

e-mail: gdlee@dau.ac.kr
We proposed optimal configuration for a film patterned retarder (FPR) with a linear polarizer in a stereoscopic three dimensional (3D) display. The proposed FPR system applied the wide-band and wide-view half-wave retarder, which consists of half-wave biaxial film and a patterned half-wave A-film. We calculated the polarization states for each film on the Poincaré sphere over all visible wavelengths based on the Stokes vector and the Muller matrix. From the calculated results of the 3D crosstalk, the left 3D crosstalk of the proposed FPR system in oblique direction could be improved by over 90% compared to the conventional FPR system.
    1. Introduction

Today, the three-dimensional (3D) displays that can perform more realistic images with depth information and vivid pictures have attracted great interest as the next-generation displays [1, 2].

Among the many stereoscopic 3D displays with 3D glasses, a shutter-glass type and a film patterned retarder (FPR) type 3D display are representative 3D display type that show good performances and unlimited viewing range [3-8]. In case of a FPR system, the binocular disparity is produced by patterned retarder, which is generally attached on the outside of the LCD panel to change the polarization state [6-8]. Currently, this type is greatly preferred by the world 3D market because it is low cost, uses lightweight glasses, has a simple fabrication process, is flicker free, and has wide-viewing angles. In spite of the optical advantage of the FPR system, however, the optical performance still shows strong dependence on the observed direction in all visible wavelength spectrums. Therefore, the 3D crosstalk, which is due to an overlap of the left and right image, is highly increased in oblique viewing angle.

In general, the FPR system can apply a quarter-wave retarder [9] or a half-wave retarder to separate the left and the right image. In this paper, we designed optimal configuration, which applied half-wave retarder with wide-band and wide viewing angle characteristics, for the FPR type 3D display. The polarization states of the separated light after passing through the FPR system was calculated by the Stokes parameter and the Muller matrix method, and was confirmed on the Poincaré sphere over the all visible wavelength spectrum in oblique viewing direction (polar angle θ=70° and azimuth angle =0°, 90°). In order to verify the enhanced optical characteristics for the proposed optimal FPR system, finally, we calculated the light leakage and compared the results to the 3D crosstalk for a conventional FPR system using the TECHWIZ LCD made by SANAYI system.

    1. Results

Figure 1(a) shows a conventional optical configuration for a FPR stereoscopic 3D display with a linear polarizer. The left side of the FPR system has zero retardation and the right side of the FPR system applies a half-wave A-film with an optical axis of 45. Thus, the polarization states of the light in front of a FPR system can be separated to vertically and horizontally linear polarizer at left and right side by patterned retarder. The viewers wearing the polarized glasses can feel a binocular disparity between the two images with different polarization states. However, the retardation film, which is used in the FPR system, shows serious problems in the observed viewing angle in all visible wavelength spectrums. One is a shift in the optical axis in each optical film due to the changing polar angle and azimuth angle in the observation direction [10]. The second problem is the change of the retardation value in the oblique incidence. The change in retardation value in each optical film as a functions of the polar and the azimuth angles of the incident light can be easily calculated by using the extended 22 Jones matrix method [11]. The last factor is the dispersion of the refractive index of the optical films with wavelength [12]. The polarization states of the three primary colors (red, green, and blue) commonly differ from one another after the light passes through the retardation films due to dissimilar material and wavelength dispersion characteristics.

Figure 1(b) show the calculated light leakage of the conventional FPR system of the right image in all visible wavelengths in normal and oblique direction. We can confirm serious light leakage from the conventional FPR system, and can show 3D crosstalk, which is caused by ghost images, due to deficient separation of the images in viewing directions. Thus, if excellent 3D images are to be obtained in the oblique and the normal directions, these problems of degraded 3D image quality in the FPR 3D display must be overcome.

(a) (b)

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