Patent ID: 8981799
Filing Date: 2015-03-17
Classification: G01R,H01J

Abstract:
1. A current measuring circuit comprising: a current-detecting resistor inserted in series between a high-voltage site and an output terminal of a power circuit that supplies a predetermined direct voltage to the high-voltage site and which generates, between both ends thereof, a potential difference proportional to a current flowing through the high-voltage site; a first resistor, a second resistor, a transistor, and a third resistor used to measure a current flowing through the high-voltage site and which are connected in series between a ground potential and the output terminal of said power circuit; a differential amplifier having a negative input terminal into which a first potential difference which is generated between both ends of said third resistor is entered, and having a positive input terminal into which a second potential difference which is generated between both ends of said current-detecting resistor is entered, and controlling a current flowing through the transistor which is connected to the output of said differential amplifier so that said first potential difference and said second potential difference become equal; and a direct voltage source that generates a direct voltage for operating said differential amplifier.