Patent ID: 8070459

Claim:
A method of setting the pressure in a chamber of a vacuum system to a required pressure, the system comprising a pressure control system including a pump for evacuating gas from the chamber, a valve down stream of the pump, and a flow controller for allowing the flow of gas into the chamber, the method comprising: setting an initial flow out of the chamber to increase a rate of pressure increase, which, if allowed to sustain beyond a transient period, would have caused a pressure in the chamber to exceed the required pressure, and setting a preset flow out of the chamber after the transient period has elapsed for achieving and maintaining the required pressure higher than an initial pressure in the chamber at a moment when the initial flow is set, wherein the setting of a preset flow comprises varying a conductance of the valve down stream of the pump, wherein the chamber is specifically used in flat panel display processes, wherein during the transient period, a speed of the pump is reduced so that an amount of gas which leaks up-stream across the pump increases so as to increase the gas flowing into the chamber, thereby reducing the transient period for the initial pressure to increase to the required pressure.