| 摘要 |
PURPOSE:To simplify the circuit constitution of the developer concn. controller by sequentially detecting a reference light quantity and a measured light quantity by the same detecting means. CONSTITUTION:Both of the direct light from a 1st LED 102 and the light which is emitted from a 2nd LED 103 and is reflected from a two-component developer 101 are alternately received time-serially in a single photodiode 104. The analog light quantity signal from this photodiode 104 is converted by an analogto-digital converter 105 to a digital light quantity signal which is supplied to a CPU 106. The CPU 106 makes prescribed computation in accordance with the digital light quantity signal received therein and detects the toner concn. in the developer 101. The 1st and 2nd LEDs 102 and 103 are alternately lighted time wise by the on/off signals from an on/off signal generating circuit 107 to be controlled by the CPU 106. |
