A high brightness and high contrast reflective LCD with an internal micro slant reflector (MSR) is developed. The internal MSR is used in a single‐polarizer configuration using mixed‐mode twisted nematic (MTN) effect. MSR is effective in boosting the brightness of reflective LCD. The results show contrast ratio more than 30 and response time less than 20ms. In the configuration of a full‐color TFT‐LCD with 60% aperture ratio, reflectivity of 35% is demonstrated.
A reflective TFT-LCD with an internal diffusive micro slant reflector (DMSR) is developed to improve the previous MSR structure [1,2]. The DMSR structure is optimized to obtain a desired light scattering disbribution cone while still preserving the asymmetry characteristics. A 6.4" VGA full-color reflective TFT-LCD with a DMSR is realized. In this paper, we will discuss the optical perperties of the panel. The measurement results show that the reflectance is 42% compared with a Lambertian white standard and the contrast ratio is larger than 20:1.
A reflective TFT-LCD with an internal asymmetric diffusive micro slant reflector (DMSR) is developed to enhance the light efficience" 3 . The DMSR structure is optimized to obtain a desired light distribution cone with asymmetric characteristics. In this paper, we will compare the optical properties of a reflective TFT-LCD panel with a DMSR structure and those of a reflective LCD with symmetric bump structure reflector. Since the light intensity distribution of a reflective LCD depends strongly on the behavior of the incident light source, we used two different incident light sources for illumination. One is collimated light, and other is diffused light. The conoscope is then used to understand the light distribution of the panels in all directions. When the collimated light source is used for illuminating the reflective LCD panel, the brightness of a LCD panel with DMSR is about 2 times of that of a LC cell with a symmetric bump type reflector. If the incident light is the diffusive type, the reflectance of a bump reflector will be independent of the viewing angles. However, the diffusive property of the new DMSR design will redistribute the reflected light so that an asymmetric viewing cone can be generated to increase the brightness in this area. The asymmetric property of the cone is a result of the slant structure. The experimental results demonstrate that the DMSR structure can redirect the collimated light in a designated area. Due to the effect of DMSR, the peak of reflected light is shifted away from the surface specular reflection and the light distribution is wider. Normal environment contains both the collimated and diffusive light. With the DMSR structure, we can utilize both light sources and make our panel much brighter, suitable for many information applications. INTRODUCTIONThe increasing demands of portable information tools with high information content, such as personal digital assistants, hand-held personal computers, and digital still cameras, have created a new market for high quality and low power consumption flat panel displays. Full-color reflective LCDs (RLCD) with merits of low power consumption, light weight, compact size and good legibility under the sunlight are the most suitable devices for such market requirements. Several types of reflective LCD mode have been proposed such as PCGH mode, PDLC mode, ECB mode, MTN mode and R-OCB mode. However, it is obviously that most of them did not show favorable performance when compare with a transmissive LCD or CRT. Among these LCD modes, MTN mode has shown high contrast ratio and high brightness. ERSO/ITRI has spent a great amount of effort in the development of single-polarizer MTN-RLCD 4 7 due to its advantages of high contrast, high brightness and high productivity. MTN mode also has some other attractive features, such as low operation voltage, wavelength insensitivity, wide viewing angle, and fast response. Recently, we have developed an internal diffusive micro slant reflector (DMSR) structure. It is well to change the diffus...
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