Research On Screen Positioning Technology Of Plasma Display Based On Computer Vision

The precision positioning is the critical technology in ultra-precision machining, storage of large capacity data, NT (Nanotechnology), precision test and other multi-fields, and it has extensive market prospect. This essay mainly studied that using the technology of computer vision as well as diffraction grating to realize position detection and high-precision positioning of the display screens. The main contents of this article can be described from severel aspects:The image processing technology based on computer vision has been studied, and also the relative technology has been applied into precision automatic alignment of plasma display. With the help of CCD camera, the initial image of mesh in the shadow mask plate as well as reticle in the basic plate can be get. Then the target is to deal with the initial image through histogram equalization, Gaussian filter, edge detection so as to remove the noise and other interferences, using the method of threshold segmentation to determine the position of reticle in the basic plate, after which, using the method of circle matching as well as genetic algorithm to detect the position of mesh, through the above two steps, the relative position relationship between mesh and reticle can be confirmed. A comparison between two methods, which are the circle matching and genetic algorithm has been carried out by using matlab simulation. The results shows that the genetic algorithm is high in precision and operation efficiency during detecting the position of mesh.The displacement detecting technique of double grating has been researched, the mathematical model of displacement deviation between gratings as well as Moire signals has been established, and also simulation research has been carried out. The result indicates that the density of Moire signals comes to periodical changes along with the relative displacement between double gratings, and meanwhile along with the distance between double gratings. It explains that after diffraction of double gratings, the Moire signals presents stable change rule, which is very appropriate for high-precision position detection. For further improving the sensitivity of position detection, the precision positioning method of differential-Moire has been discussed.On this basis, the precision positioning device of SMPDP has been developed out. The precision driving systems as well as the precision detecting systems have been designed. These systems make micro-positioning table as the core, and use computer vision technology and grating sensor to detect the position deviation. The driving mechanism is composed by coarse positioning mechanism and fine positioning mechanism. The former one adopts impulse subdivided stepping motor, with the help of precision ball screw, the tiny angles subdivided by stepping motor can be changed into micro-grade linear displacement, then the coarse positioning can be realized through this way. The latter one adopts piezoelectric ceramics actuator, takes flexible hinge as the drive mechanism, and then driving the positioning table to move, the fine positioning can be realized through this way. During the process of positioning, the errors can be eliminated by computer close-loop control.In order to realize high-precision positioning in the large-route of the screen panel, the combination positioning technology which combines both coarse positioning and fine positioning has been put out. In the part of coarse positioning, computer vision detecting technique has been used, by analyzing the initial image according to the camera to detect the relative position relation between the reticle and mesh, then the control command has been given out, with this command, the driving table has been driven into the range of coarse positioning, which is±60?m. After the coarse positioning, the computer sends out control command to the driving mechanism according to the size and polarity of the received Moire signals, and then drives positioning table into the error range of fine positioning, which is±0.4?m.