| With the rapid development of MEMS (Micro Electromechanical System) technology and multi-development of display devices, the research of MEMS-based light modulators for display applications has become one of the most important research focuses, and which has become an important branch to promote next generation of display industry. But domestic research on these devices is now relatively lagged and restrained by international patents, so there is a great importance and potential value to develop a novel MEMS-based light modulator and relevant core display controlling circuits for display application with independent intellectual property rights.Under this background and urgent needs, a novel MEMS-based grating light modulator GMLM(Grating Moving Light Modulator) project was just prompted by Chongqing University. In this paper, electromechanical model of GMLM was established according to the operation principle. And the electromechanical characteristics were analyzed theoretically and simulated by FEA(Finite Element Analysis). The characteristics and structural parameters of the device were analyzed and simulated to obtain an optimization structure. In terms of electromechanical characteristics, the driver circuits of the device were analyzed and designed. Then the driver circuits of GMLM were designed and developed, furthermore, the research and relevant experiment for the controlling test system and display test system of 16×16 GMLM array were accomplished. The main work of this paper is as following:①To theoretically analyze GMLM, the effective spring-capacitance model and mechanical model were established by using micro-structure mechanics theory. Electromechanical parameters such as operation voltage, pull-in voltage and resonance frequency of GMLM were analyzed by both theory and CoventorWare FEA simulation, which have similar results. Its performance specifications are as followings: operation voltage: 4.3V, pull-in voltage: 5V, resonance frequency: 0.47MHz and response time: 40μs. And the test to the sample GMLM shows: operation voltage: more than 20V and response time: 80μs.②According to structure parameter analysis for device operation voltage, pull-in voltage, resonance frequency, effective diffraction area and residual stress, correlative optimization projects for improving effective diffraction area and suppressing the curving caused by residual stress were achieved. Compared with the former structure, the effective diffraction area can rise up 3 times around and the deflection caused by residual stress can reduced to about 5%, which was validated via simulation by FEA and the test by the Veeco Laser Profiler.③Both inner and exterior driver circuits of GMLM were designed according to the special electromechanical characteristics. The inner CMOS circuit which can control the device charge and discharge collaborates with the exterior address circuit to operate GMLM array scanning drive.④Due to the need of testing GMLM sample, hardware circuits and software environments of the test controlling system were designed and experimented by SOPC technology. This system includes: RS232 which is used as the communication interface with PC, FPGA which is used as the hardware for disposing information, Nios core which is Customized as the CPU, application program which is built by C language. The system can realize real-time, on-line and untouched testing some parameters such as: the optical and electrical couple phenomena among pixels, the operation frequency, etc.⑤According to the need of testing the display performance of GMLM, the display test system was designed and experimented. In this system, USB controlling unit, data format transforming unit, gray modulating unit and scan controlling unit were designed and built in FPGA by VHDL hardware description language with USB2.0 as communication interface. The system can achieve 16×16 array real-time and on-line display the 16-grade gray digital image data that transmitted from PC in the model of 60fps and progressive scanning. |
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