Method and apparatus for calibrating the gas pressure in a vacuum working chamber (vacuum coating chamber or recipient)

摘要

The residual gas pressure is measured in the evacuated process chamber (1) and is used to determine the required gas pressure in the calibrating pressure vessel (2). The process chamber (1) is evacuated and the residual gas pressure is measured to produce a signal for a computer. A calibrating factor is determined by the computer on the basis of this signal and a target working pressure in the chamber. An amount of gas with pressure (P) corresponding to an output signal proportional to the calibrating factor is introduced into a calibrating pressure vessel (2) whose volume (v) is smaller than the volume (V) of the process chamber (1). The gas from the pressure vessel (2) is transferred under isothermal conditions into the process chamber (1) to produce the specified working pressure equal to P (V+v). An Independent claim is also included for an apparatus which is characterized by a calibrating pressure vessel (2) which is connected via control valves (3, 4) respectively to an inert gas source and to the process chamber (1). Both the process chamber and the calibrating pressure vessel are connected via pressure sensors (5, 6) to a computer unit (7) governing the valves (3, 4) by means of a control unit (8).