| 摘要 |
PURPOSE:To obtain a developing device suitable of an electrophotographic device constituted so that a stable image quality is obtained and the speed of an image forming process can be switched over by controlling a bias voltage impressed on a developer carrier according as the speed of the image forming process is switched over. CONSTITUTION:By adjusting a speed switching mechanism 11, the feeding speed of a transfer material 9 and the rotational speed of a photoreceptive drum 1 are synchronously changed. In such a case, when some speed is set by the switching mechanism 11, the output signal thereof is sent to a control part 16 and a control signal corresponding to the output signal of the switching mechanism 11 is outputted from the control part 16. Then, the output of a high-voltage power source 17 connected to a developing roll Jl is controlled. That is, when the speed of the process is expressed by circumferential speed ratio between the drum 1 and the roll 4, the bias voltage is set to be low when the circumferential speed ratio is high and set to be high when it is low. Thus, the quantity of toner supplied to the drum 1 from the roll 4 can be made equal at a developing time by the respective circumferential speed ratio. |
