| 摘要 |
PURPOSE:To prevent the influence of noise to be inflicted on a 1st power source side, by providing a light source which is turned on by the 1st power source, a 2nd power source composed of an element which generates an electric power upon receiving the light of the light source, and electronic circuit which is provided with the 2nd power source and supplied its electric power from the 2nd power source. CONSTITUTION:A light source lamp 22 is made to light by an external AC power source 23 which is connected with a main body 1 and used as the 1st power source, and a photocell 20 used as the 2nd power source generates electric power and actuates a toner concn. detecting circuit 14 upon receiving rays of light from the lamp 22 through an optical fiber 21. A toner concn. controlling means 15 on the main body 1 side is provided with a phototransistor 16 acting as the receiving section to the circuit 14 and actuates and stops the toner supply ing device of a developing device 6 in accordance with the signal of the transis tor 16. Namely, when the phototransistor 16 detects the lighting of an LED 19, the transistor 16 actuates the toner supplying device. Therefore, transmission of noises on electric signals can be cut. |
