| 摘要 |
PURPOSE:To prevent image quality from lowering even if external temperature environment is changed by providing a circuit which corrects temperature characteristic in development by making a developing bias voltage impressed on the developing roller of a developing deice possess the temperature characteristic. CONSTITUTION:An electrostatic latent image is turned into a visible image by making toner adhere by means of the developing roller 7a and transferred on recording paper 2 by means of a transfer charger 8. A certain negative bias voltage -E is impressed on a replenishment roller 7b and negative bias voltage -E'' possessing the temperature characteristic is impressed on the developing roller 7a. Namely, a series circuit of a thermistor TH and a resistance RB which are thermosensitive resistance elements having the negative temperature characteristic is provided between a power source input terminal IN where a certain bias voltage -E is supplied and an earth terminal GND and a voltage Vb at a voltage dividing point (b) is impressed on the developing roller 7a from an output terminal OUT as the developing bias voltage -E''. Thus, even if the external temperature environment is changed, the temperature characteristic in development can be corrected with the temperature characteristic that the developing bias voltage is made to possess, and uniform developing action is always performed. |
