Super Clean Non-Contact Conveying System Utilizing Electrostatic Force

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To reduce the contamination of product surfaces by duet particle in manufacturing process of Liquid Crystal Display (LCD) or semiconductors, the development of non-contact conveying system for glass plate or silicon wafer is essentia1. Furthermore, in proportion to the large-sizing tendency of LCD, the conventional transportation system utilizing vacuum chuck fixing on the end-effecter of robot arm gives a pretty deflection on the glass base-plate. Because of the two reasons mentioned above, the development of a new conveying system for thin glass plate is required.In this research, an electrostatic suspension chuck for thin plate has been successfully developed. For the purpose to levitate a thin plate, which should be considered as a flexible object, the operating force on each small area of the thin plate during levitation has to be controlled. The electrode employed for generating electrostatic levitation force was divided to pieces, and the applied voltage to each electrode unit w … More as controlled based on the output of the corresponding gap sensor. A prototype mechanism was confirmed to levitate a thin aluminum plate of 278mm x 78mm x 0.05mm in size, with a gap of around 0.5mm steadily beneath the electrode plate. The vertical vibration amplitude was about ±5μm, which was the resolution of the gap sensor. Another prototype mechanism wag also constructed to levitate a soda-lime glass plate of 385hm x 130mm x 0.7mm in size. Despite of the glass's high surface resistivity, which would deteriorate the stability of levitation, we succeeded in the levitation of the mentioned glass plate.In this research, we also successfully developed a new non-contact conveying system for thin glass plate, utilizing combination of air bearing and electrostatic propelling. An appropriate structure for electrode was proposed, and its effectiveness was confirmed through the force measuring and conveying experiment. A soda-lime glass plate of 52mm x 52mm x 0.7mm in size wag conveyed at a speed of 150mm/s with a lateral vibration less than ±0.5mm, when the gap width was 130μm. Less