Inverter apparatus

An inverter apparatus which converts an input voltage into an AC driving voltage, and which supplies the AC driving voltage thus converted to a plurality of loads, including:

• a transformer having a primary winding and a secondary winding;
• a switching circuit including a plurality of transistors connected to the primary winding of the transformer, and which alternately applies, to the primary winding of the transformer, the input voltage and a fixed voltage which is lower than the input voltage according to the ON/OFF operations of the transistors;
• a plurality of ballast capacitors which are respectively provided for the plurality of loads, and of which one terminal of each ballast capacitor is connected to the secondary winding of the transformer so as to form a common terminal, and the other terminals of which are respectively connected to the plurality of loads;
• a control circuit which monitors an electric current that flows through a predetermined current path among current paths included in the entire circuit including the inverter apparatus and the loads, and which feedback controls the ON/OFF states of the plurality of transistors included in the switching circuit such that the current thus monitored is maintained in a predetermined state, thereby adjusting a switching electric power supplied to the primary winding of the transformer;
• and
• an abnormal state detection circuit provided for a load which is a monitoring target selected from among the plurality of loads,
• wherein the abnormal state detection circuit includes:
• a first capacitor and a second capacitor arranged in this order in series between a connection node that connects the load to be monitored and the ballast capacitor that corresponds to the load and a fixed voltage terminal;
• and
• an abnormal state judging unit which compares the voltage at a connection node which connects the first capacitor and the second capacitor with a predetermined threshold voltage.