Patent ID: 7995324

Claim:
An electrostatic attraction apparatus for a glass substrate, comprising: an attraction plate made of a dielectric in which at least one first electrode and at least one second electrode are disposed inside; a first power source for applying a voltage to the first electrode; a second power source for applying a voltage, having an opposite polarity of the first electrode, to the second electrode; attraction detecting elements for detecting attraction of a glass substrate to the attraction plate; temperature detecting elements for measuring or estimating a temperature of the glass substrate; and controlling elements for controlling the voltages of the first power source and the second power source on the basis of detection results from the attraction detecting elements and the temperature detecting elements, wherein the glass substrate is electrostatically attracted to the attraction plate and then the glass substrate is released from the attraction plate by application of the voltages to the first electrode and the second electrode, and wherein the controlling elements presets a size, specific gravity, and electric resistivity of the glass substrate and presets an attraction time period necessary for attraction of the glass substrate, a holding time period for holding an attraction state of the glass substrate, and a release time period necessary for releasing the glass substrate, the controlling elements finds an attraction force necessary for attraction of the glass substrate on the basis of the size and the specific gravity of the glass substrate and the attraction time period, the controlling elements finds an attraction voltage necessary for obtaining the attraction force and finds a holding voltage for holding the attraction state and a release voltage for releasing on the basis of the electric resistivity and the temperature of the glass substrate measured or estimated by the temperature detecting elements, the controlling elements measures an actually measured attraction time period taken to complete attraction of the glass substrate when attraction of the glass substrate is detected by the attraction detecting elements after application of the attraction voltage, the controlling elements compares the preset attraction time period with the actually measured attraction time period, and recalculates the holding voltage and the release voltage based on the actually measured attraction time period when the preset attraction time period is different from the actually measured attraction time period, and the controlling elements holds the attraction state and releases the glass substrate by use of the recalculated holding voltage and the release voltage.