TONER CARRIER, DEVELOPING DEVICE, IMAGE FORMING DEVICE AND PROCESS UNIT

摘要

PROBLEM TO BE SOLVED: To optimize a groove depth so as to prevent undeveloped toner from existing and suppress variation of a developing toner amount with the passage of time not to generate an abnormal image.SOLUTION: A developing roller 42 holding toners in the outer peripheral part thereof comprises: a plurality of first grooves L1 parallel to each other and formed in a direction inclined from an axial direction of the developing roller 42 at approximately equal intervals; a plurality of second grooves L2 similar to the plurality of first grooves L1 and crossing each of the first grooves L1; protrusions 42a having approximately planar top surfaces in areas surrounded by the first and second grooves L1 and L2; and groove wall surfaces LS of the first and second grooves L1 and L2 formed in side surfaces of the protrusions 42a. The groove wall surfaces LS of the first and second grooves L1 and L2 are approximately V shaped. When h represents depths of the first and second grooves L1 and L2, &thetas; represents opening angles of the approximately V shaped grooves L1 and L2, R represents a volume average particle diameter of the toners, the relationship of h-R/2-{(R/2)/sin(&thetas;/2)}>R is satisfied.