Abstract: In a rotation detection apparatus, a magnetism pattern section provided with plural magnetic poles and a FG (frequency generating) pattern section provided with plural toothed wire circuits are located so as to face each other. When either one of the magnetism pattern section and the FG pattern section is rotated together with a rotating member, plural wave signals are electrically induced in the plural toothed wire circuits. A signal processing cicuit synthesizes the plural wave signals so as to output a multiplication signal and detects the rotation of the rotating member based on the multiplication signal.

Abstract: A developer in use with an image forming apparatus. The developer includes: a developing sleeve which rotates and holds toner on itself so as to develop a latent image on a photoreceptor with the toner; a driving motor for generating a rotational driving force; a drive transmission for transmitting the rotational driving force of the driving motor to the developing cartridge in which the drive transmission has a transmitting state and an untransmitting state; and a shock easing controller or member for easing a shock of transmission of the rotational driving force to the developing sleeve in the transmitting state, in which the shock easing controller or member is provided in at least one of the driving means and the drive transmission means.