Patent ID: 7826773
Filing Date: 2010-11-02
Classification: G03G

Abstract:
1. An image forming apparatus for forming a color image on a recording material, comprising: (i) mounting means for detachably mounting a plurality of process cartridges each including a photosensitive drum and a developing roller for developing an electrostatic latent image formed on said photosensitive drum, said process cartridges including a black process cartridge containing a black color developer and a non-black process cartridge containing a non-black developer; (ii) a driving source; (iii) a first clutch for connecting and disconnecting between said driving source and said developing roller for selective driving force transmission to the black process cartridge; (iv) a second clutch for connecting and disconnecting between said driving source and said developing roller for selective driving force transmission to the non-black process cartridge; (v) a movable first member actable on said first clutch for switching between an operation state for transmitting the driving force to said developing roller and a non-operation state not transmitting the driving force thereto; (vi) a movable second member, actable on said second clutch, for switching between an operation state for transmitting the driving force to said developing roller and a non-operation state not transmitting the driving force thereto; (vii) a switching member, movable by the driving force of said driving source and actable on said first member and second member, for switching among a first mode for transmitting the driving force to said developing rollers of all of said process cartridges, a second mode for not transmitting the driving force to any one of said developing rollers, and a third mode for transmitting the driving force only to said developing roller of said black process cartridge, wherein said switching member includes a rotatable shaft portion, a first cam portion for contacting said first member to move said first member, said first cam portion being rotatable with said shaft portion, and a second cam portion for contacting said second member to move said second member, said second cam portion being rotatable with said shaft portion; and (viii) a third clutch for connecting and disconnecting between said driving source and said shaft portion for selective transmission of the driving force, wherein said third clutch is capable of stopping said shaft portion for each predetermined angle within one full turn of said shaft portion.