Electromechanical Characteristic Analysis of Passive Matrix Addressing for Grating Light Modulator

Zhu Jin,Zhihai Zhang,Shanglian Huang,Zhiyu Wen

doi:10.3390/s90302162

Abstract

A Grating Light Modulator (GLM) based on Micro-Electro-Mechanical Systems (MEMS) is applied in projection display. The operating principle of the GLM is introduced in this paper. The electromechanical characteristic of the passive matrix addressing GLM is studied. It was found that if the spring constant is larger, both the response frequency and the driving voltage are larger. Theoretical analysis shows that the operating voltage and the pull-in voltage of the GLM are 8.16 and 8.74 V, respectively. When an all-selected pixel in a m×n array is actuated by a voltage V0, the voltages of the half-selected pixel in row and column are V0(m–1)/(m+n–1) and V0(n–1)/(m+n–1), respectively, and the voltage of the non-selected pixel is V0/(m+n–1). Finally, the experimental results indicate that the operating voltage and the pull-in voltage are 7.8 and 8.5V respectively, and the response frequency of the GLM is about 7 kHz. The crosstalk in a 16×16 GLM array is validated by the experiment. These studies provide a theoretical basis for improving the GLM driver.

Highlights

With the development of Mechanical Systems (MEMS) technology, light modulators based on optical MEMS for projection displays have become a popular research focus [1,2,3]
It can be concluded that the square-wave voltage of the half-selected pixel in Figure 12e is about 1V, which is consistent to the theory that the voltage of the half-selected pixel is half of the all-selected pixel in the 16×16 Grating Light Modulator (GLM) array
The results show that when an all-selected pixel is actuated by a voltage, the voltage of the half-selected pixel is much larger than the voltage of the non-selected pixel, but it is smaller the voltage of the all-selected pixel, which agrees with the crosstalk theory of the matrix capacitance

Summary

Introduction

With the development of MEMS technology, light modulators based on optical MEMS for projection displays have become a popular research focus [1,2,3]. DMD is a precise light switch, and the mirror is rotated through the electrostatic attraction produced by the voltage difference between the mirror and the underlying memory cell. The structure of a GLV is very simple, but it is a linear array, which needs a scanning device for displaying a 2D image. This scanning device increases the complexity and the assembly difficulties of the projection system. We propose a novel Grating Light Modulator (GLM) [6,7] with a two layer structure. Its process is simpler than DMD, and the GLM can form two-dimensional modulator arrays, and with these 2D modulator arrays, the scanning device is eliminated, and the projection system can be simpler

Methods

Results

Conclusion