Patent ID: 7796368

Claim:
A high-frequency power supply system for supplying high-frequency power from a high-frequency power source to a load via an impedance matching unit, the system comprising: a first detector for detecting information about a forward wave traveling from the high-frequency power source toward the load; a second detector for detecting information about a reflected wave traveling from the load toward the high-frequency power source; a differentiator for calculating a change of a magnitude of reflection coefficient per unit time at a detection point provided for the first and second detectors based on the information about the forward wave detected by the first detector and the information about the reflected wave detected by the second detector; an anomaly determiner for determining an occurrence of an anomaly on a side toward the load as from the detection point provided for the first and second detectors based on the change of the magnitude of reflection coefficient per unit time calculated by the differentiator; and a determination prevention unit for preventing the anomaly determiner from performing a determining operation upon commencement of a power supply operation of the high-frequency power source or upon a change made on an output power value setting during the power supply operation, until a predetermined time period has passed.