| 摘要 |
PURPOSE:To eliminate the necessity of insertion of a sensor and electronic circuit into a developing machine and to simplify the structure and reduce the cost of the developing machine, by producing a toner supply signal from an electric video signal corresponding to picture information. CONSTITUTION:Whenever a signal which turns on a semiconductor 2 arrives out of picture signal 1, the signal of an AND gate 15 is outputted and the gate of a sample holding circuit 13 is opened and a voltage is sample-held, and thus, the level is changed. The output signal of the circuit 13 is inputted into a comparator 16 and compared with the signal of a reference voltage generator 17. When the output signal of the circuit 13 becomes equal to or higher than the level of the signal from the generator 17, the output signal of the comparator 16 becomes ''1'' and this signal is inputted into a toner supply driving circuit 18 and a fixed amount of toner is supplied to a developing machine 5. Moreover, the output signal of the comparator 16 is inputted into the circuit 13 as a clear signal and clears the circuit 13, and then, sets the hold signal of the circuit 13 to zero. |
