Research On The Deformation Of The Liquid Crystal Glass Substrate At The Gap Of The Air Floating Platform And Parameter Design Of The Air Floatation System

With the development of larger scale and thinner thickness of the LCD glass substrates,air bearing,as an ideal bearing method,has been widely used in high generation glass substrate production and testing equipment.During the optical automatic detection of large glass substrate defects,it is necessary to detect the type,size and position of various defects on the glass substrates.Undoubtedly,the deformation of the glass substrate under the support of air floatation will interfere with the detection accuracy.Excessive deformation may even cause cracks on the glass substrate or contact with the air float plates during the transmission.Therefore,studying the deformation of the glass substrate during the support and transmission of the air floatation is significant for the parameter design of the air floatation system.The glass substrate will produce large deformation at the edges and gaps of the air bearing,which should be paid attention to in engineering design.In this paper,combined with the special project of "Development and Application of Automatic Optical Inspection Instruments for LCD Flat Panel Display",we carried out the research on the bending deformation of the glass substrate in the asymmetric gas film flow field at the edges and gaps of the air floatation platform as followed: obtaining the load concentration of the gas film flow field on the glass substrate based on the theory of gas lubrication,deriving the bending deflection equation of the thin plate under lateral load based on the elasticity theory of thin plate,solving the deformation of the glass substrate in the asymmetric gas film flow field,acquiring the relationship between the load concentration,deflection and gas film gap of the glass substrate,finding out the maximum deflection at the gap between the air floating plate in the detection area and the transmission area.With the help of CFD software,the deformation of the liquid crystal glass substrate supported by the asymmetric air floatation unit is simulated.It is determined that the reasonable value of the thickness of the gas film at the edge of the air float plates combined with theoretical analysis from the aspects of satisfying the maximum deformation of the glass substrate not exceeded to allow the value,the stability of the pressure distribution on the gas film surface,and saving the gas supply flow.Through simulation analysis of the air bearing unit support model,the effects of the gap between the air float plates,the distance between the air injection holes,the air supply pressure and the air supply arrangement on the glass deformation are compared in detail.By analyzing the relationship among the pressure distribution of the gas film surface,the mass flow consumption and whether the gas film gap and the maximum deflection value condition are satisfied under different parameters,the air float parameters of the detection area and the transmission area are optimized respectively.Participated in the development of an engineering prototype for automatic optical detection instruments for the LCD flat panel display and tested the deformation of the glass substrate on the developed engineering prototype through experiments.Experimental test results show that the maximum deformation of the glass substrate meets the requirements of the allowable value.The research results of this paper have a universal reference value for the deformation of open thin plate parts in the air bearing and transmission system and the parameter design of the air floatation system.