Deformation of large liquid crystal display glass sheets across a gap between noncontact transportation devices

Abstract In recent years, large mother glass sheets with high resolutions have been used for electric devices, such as television panels, personal computer monitors, and cell phones, particularly to reduce manufacturing costs and improve production efficiencies. Accordingly, high-speed inspection processes for detecting defects in thin-film transistor arrays using charge coupled device (CCD) cameras have become very important, and a noncontact transportation technique for the high-speed inspection section is necessary to avoid damage to the glass sheets during inspection processes. Furthermore, a gap of around 100 mm between transportation devices is needed for the inspection area of the CCD cameras to project an inspection light from underneath the glass sheet. This means that the capability to make a large, thin glass sheet jump over the gap is required for the noncontact transportation device. In this paper, an air-levitating transportation device that had air-supply pads with orifice restrictors and vacuum ports was proposed to support a 500 mm square, liquid crystal display glass sheet. The deformation of the glass sheet supported by the proposed transportation device was investigated numerically and experimentally when the glass sheet jumped over the gap between the proposed devices. In addition, the optimum combinations of air supply and vacuum pressures and their areas in the proposed device were studied for obtaining the largest jumping distance of the thin glass sheet. It was found that by properly selecting supply and vacuum pressures and their areas, the largest jumping distance supported by the proposed device could reach approximately 75 mm.