Patent ID: 7751760

Claim:
An image forming apparatus comprising: an image bearing member for bearing a latent image; a developer bearing member for transporting developer to an opposing position opposing the image bearing member by rotating with developer being borne thereon, the developer bearing member having regularly-disposed concave sections formed on a surface thereof; and an alternating voltage applying section for applying to the developer bearing member an alternating voltage that includes a first voltage for moving developer from the developer bearing member toward the image bearing member and a second voltage for moving developer from the image bearing member toward the developer bearing member in order to develop the latent image using the developer that has been transported to the opposing position, wherein a cycle period of the alternating voltage is larger than a value obtained by dividing a minimum width of the concave section in a circumferential direction of the developer bearing member by a moving velocity of a surface of the developer bearing member during rotation of the developer bearing member, the moving velocity is variable, and when the moving velocity is changed, the cycle period of the alternating voltage is changed so that the cycle period of the alternating voltage is larger than a value obtained by dividing the minimum width by the moving velocity.