| 摘要 |
PURPOSE:To stabilize control of the toner concentration even if a cassette size cannot be detected, by detecting the size of a loaded paper supply cassette or the copy size of fed papers and controlling the quantity of toner supply on a basis of this detection result. CONSTITUTION:A size detection signal PA of a paper supply cassette 28 in the upper stage from an upper cassette size detector 53, a size detection signal PB of a paper supply cassette 29 in the lower stage from a lower cassette size detector 54, a selecting signal PC from a cassette selecting switch, and a form detection signal PD from a form detector 55 are inputted to a main control circuit 60. Further, supply quantity selecting signals PE and PF from a toner supply quantity selecting switch 62 and clock pulses PG from a timing pulse generator 63 are inputted to the circuit 60. A toner supply clutch 64 is controlled to be turned on or off on a basis of a corresponding toner supply quantity set value and these input signals, and a supply shaft 25 is rotated to control the toner quantity supplied from a toner tank to a developing device. Thus, the toner concn. is stabilized. |
