Apparatus for determining whether door is open or closed and image forming apparatus

An image forming apparatus comprising:

• an output portion configured to output a DC voltage having been converted from an AC voltage;
• a switch portion having an end connected with said output portion, said switch portion being configured to supply the DC voltage outputted to said output portion to a load when said switch portion is in a closed state, and to shut off the supply when said switch portion is in an open state;
• a capacitor connected with the other end of said switch portion;
• and
• an openable member configured to permit access into said image forming apparatus, wherein said switch portion is in the open state when said openable member is opened, and said switch portion is in the closed state when said openable member is closed;
• a discriminating portion configured to discriminate whether said switch portion is in the open state or the closed state on the basis of a change amount of a voltage of the other end of said switch portion,
• wherein said discriminating portion is swichably operable in a first mode in which a first DC voltage is outputted from said output portion and a second mode in which a second DC voltage lower than the first DC voltage is outputted from said output portion, and
• wherein, when the mode is switched between the first mode and the second mode, said discriminating portion discriminates the state of said switch portion on the basis of the change amount of the voltage at the other end of said switch portion in a predetermined time period.