Bias output apparatus including a plurality of voltage output circuits, and image forming apparatus

An image forming apparatus comprising:

• an image forming unit configured to form an image on a sheet;
• and
• a bias output circuit configured to generate and output a bias voltage used when the image forming unit forms the image on the sheet,
• wherein the bias output circuit includes:
• a plurality of voltage output circuits, each configured to output the bias voltage and a determination voltage generated based on the bias voltage;
• a determination circuit configured to output a binary determination signal on the basis of the determination voltages output by each of the plurality of voltage output circuits;
• and
• a controller configured to control the plurality of voltage output circuits and determine whether or not the plurality of voltage output circuits are operating normally based on the determination signal output by the determination circuit,
• wherein the controller is further configured to determine that the plurality of voltage output circuits are operating normally if an output pattern of the determination signal is a predetermined first pattern while the controller is controlling the plurality of voltage output circuits to output the bias voltages in order.