Plasma Display Screen Board Automatic Precision Positioning System,

The technology of precision positioning plays a pivotal role in the production of the Shadow- Mask Plasma Display Panel (SM-PDP), and makes it possible that the SM-PDP can display good images. This dissertation focuses on the fundamental theory and key technology of precision position detection and precision positioning based on laser Moirésignals. The advances in precise detection and position have all been enabled by applying the technology to industrial control.The relationship between displacement of double diffracting gratings and the intensity of Moirésignal is studied by applying theories of physics optics and Fourier optics, a mathematical model of linear displacement measure based on the Moirésignal is established, and computer-simulated pattern changes are obtained. The fundamental theory of precise positioning and basic rule of precise positioning were explored. The research results were applied to develop SM-PDP precision positioning device. The computer controlled alignment device can achieve high-accuracy position detection and precise positioning using CCD and laser-Moire sensors. The mechanical drive system of the precision platform is composed of stepping-motor in micro step mode and precise screw drive set, which can translate small rotational movement into sub-micron level linear movement. The final alignment error is mainly eliminated through computer controlled closed loop so as to alienate the precision requirements of the mechanical drive system. On the SM-PDP precision positioning device, the precise plane positioning technique was studied. The best control strategy of precise plane positioning is developed by analyzing the relationship between plane positions and corresponding Moire signals. On this control strategy, the alignment device could realize x-y-θthree-freedom full automatic precision plane positioning so that it could achieve automatic precision positioning of front substratum, shadow mask and behind sub stratum, the fine alignment accuracy could be±5μm.