High-voltage power unit and mass spectrometer using the power unit

A high-voltage power unit, comprising, for selectively outputting a high voltage of positive or negative polarity:

• a positive voltage generating circuit for generating a positive high voltage;
• a negative voltage generating circuit for generating a negative high voltage;
• and
• a control circuit for controlling each of the positive high voltage generated by the positive voltage generating circuit and the negative high voltage generated by the negative voltage generating circuit, wherein
• one of a pair of output terminals of the positive voltage generating circuit is connected to one of a pair of output terminals of the negative voltage generating circuit to connect the two voltage generating circuits in a series connection, and
• one of two terminals of the series connection is used as a reference side, while the other terminal is used to take out a high-voltage output whose polarity is switched,
• the high-voltage power unit further comprising:
• a) a first current source disposed in between the pair of output terminals of the positive voltage generating circuit for supplying a variable current from a high voltage side to a low voltage side, the variable current having a maximum current limited to a predetermined value;
• b) a second current source disposed in between the pair of output terminals of the negative voltage generating circuit for supplying a variable current from the high voltage side to the low voltage side, the variable current having a maximum current limited to a predetermined value;
• c) a first output driver for driving the second current source to change a current supplied from the second current source based on a voltage or a current appearing on the pair of output terminals of the positive voltage generating circuit;
• and
• d) a second output driver for driving the first current source to change a current supplied from the first current source based on a voltage or a current appearing on the pair of output terminals of the negative voltage generating circuit.