Patent ID: 8577243

Claim:
An image forming apparatus comprising: a photosensitive member; an exposure unit configured to expose the photosensitive member in accordance with an image signal; a developing unit configured to develop, using a toner, an electrostatic latent image formed on the photosensitive member exposed by the exposure unit; a voltage applying unit configured to apply to the developing unit a voltage; a main clock generation unit configured to generate a main clock signal; an alternating-current voltage control signal generation unit configured to generate an alternating-current voltage control signal representing a period and a duty ratio of an alternating-current voltage based on the main clock signal; a parallel-to-serial conversion unit configured to sample the alternating-current voltage control signal and other control signals input in parallel in synchronization with a sampling signal generated according to the main clock signal, to convert the sampled alternating-current control signal and the sampled other control signals into serial signals, and to output the serial signals and the sampling signal; and a serial-parallel conversion unit configured to convert the serial signals into parallel signals in synchronization with the sampling signal and to output the sampled alternating-current voltage control signal and the sample control signals in parallel, wherein the voltage applying unit uses an alternating-current voltage having a period and a duty ratio represented by the sampled alternating-current voltage control signal output by the serial-to-parallel conversion unit, and wherein a frequency of the sampling signal is an integral multiple of a frequency of the alternating-current voltage control signal generated by the alternating-current voltage control signal generation unit.