Patent ID: 8824935

Claim:
A development device for causing a developer to adhere to an electrostatic latent image formed on a latent image bearer, the development device comprising: a developer container for containing the developer; a rotary cylindrical developer carrier disposed in the developer container, facing the latent image bearer, the developer carrier including: an outer electrode including multiple electrode portions arranged in a circumferential direction of the developer carrier, an inner electrode provided on an inner circumferential side of the developer carrier from the outer electrode and electrically insulated from the outer electrode, an insulation layer disposed between the outer electrode and the inner electrode, and a surface layer provided on an outer side of the outer electrode; and a first bias power source to apply a first bias voltage and a second bias voltage to the inner electrode and the outer electrode, respectively, the first bias power source causing an electrical potential difference that changes with time between the inner electrode and the outer electrode to cause the developer to hop on a circumferential surface of the developer carrier, wherein at least one of the first bias voltage and the second bias voltage has a cyclic waveform having a predetermined frequency, wherein pulse-on time in a single cycle of the cyclic waveform is 50% of the single cycle or less, and wherein either a rising edge or a trailing edge of the pulse-on time of each of the outer electrode and the inner electrode is adjusted to set an electrical potential difference between the outer electrode and the inner electrode to Vpp/2, wherein Vpp is defined as a peak-to-peak voltage.