| 摘要 |
PURPOSE:To accurately perform toner end detection and toner supply by making a toner end display when it is judged again that toner runs short after toner is supplied for a certain time when the output of a toner detection sensor is compared with a predetermined value and larger. CONSTITUTION:A timer circuit 26T counts the detection signal of a toner detection sensor 23, i.e. the time (t) or the number (n) of pulses corresponding to the time and a comparator compares the number (n) with the predetermined no-toner value tA or nA and judges the toner end state when t>tA or n>nA. Further, a CPU 26 turns on a clutch mechanism 24 and supplies toner from a toner cartridge 10 to a developing device 11. When the toner detection sensor 23 detects the toner end state after toner is supplied for the certain time and then judges the toner and again, the clutch mechanism 24 is turned off to make the toner end display when a laser printer is in printing operation or stop a driving motor 25 and then makes the toner end display when not. Consequently, the toner end detection and toner supply are accurately performed. |
