Abstract: Bidirectional communication is carried out between a toner bottle end communication device disposed in a toner bottle and a main body end communication device disposed in a device main body while the toner bottle is moved from a first position where the toner bottle starts being attached to the device main body to a second position where the toner bottle is completely attached. The CPU provided in the main body end communication device decides whether or not the information on the toner bottle received from the toner bottle end communication device matches the device main body, and notifies prior to toner refilling. If the toner bottle is not suitable, the CPU specifies a lower quality image forming condition under which operation conditions for the main charging device, exposure device, and fixing device are changed so as to produce an image of relatively low quality in comparison to normal quality.

Abstract: In a power control unit for controlling a power supply to a load connected to an AC power source by switching on half cycles, following three modes are carried out in the order of presented: a first control mode for continuously supplying a power which is composed of a plurality of half cycle switching waveforms of a first polarity to said load; a second control mode for continuously supplying a power which is composed of a plurality of half cycle switching waveforms of a second polarity to said load, said second polarity being different from said first polarity; and a third control mode for supplying a power of a half cycle of said first polarity and a power of a half cycle of said second polarity to said load in turn. This arrangement can attain an effect that both the harmonic noises and the flickers caused by a rush current are reduced.