TRIZ-Based Design of an LCD for Projectors

TRIZ, Russian acronym for "Theory of Inventive Problem Solving" is now becoming well known and being applied to the various engineering field in the Western and Asian countries. However, as only few successful examples on the problems in microelectronics are found in the literature. Therefore, the previous work on a small high resolution TFT-LCD (Thin Film Transistor Addressed Liquid Crystal Display) for projection display was investigated and analyzed from TRIZ point of view to see its usefulness to solve engineering problems in the microelectronics field.There was a conflict between existence of spacers necessary to keep cell gap of LCD (Liquid crystal Display) uniform, which is related to the transmission uniformity of the screen, and serious degradation of image quality due to existence of spacers, which are recognized as a bright spot on the dark screen, as the spacer size compared with pixel size becomes large. The problem was analyzed by the TRIZ framework, and the solution to the above conflict in manufacturing an LCD for projection display was found systematically by utilizing TRIZ framework.Also, further problem of conflicting features between “productivity” and “manufacturing precision” and several other issues in production of small TFT-LCD for projection displays are studied by using TRIZ framework, and get to a new device structure and fabrication process as a FIR (Final Ideal Result). In this approach, TFT array formed on the Si wafer is transferred onto the other substrate such as glass with high strain-point, Eagle XG, and AN100, etc. used in the TFT-LCD industry. The hydrogen exfoliation technique and fragile layer are exploited to transfer device layers to the other substrates. In the present proposal, TFTs are perfect single crystal, in contrast to the poly-Si TFT used in the current LCDs, and this eliminates issue of characteristics variation stemming from the grain boundary of Poly-Si.