| 摘要 |
PURPOSE:To obtain a satisfactory image, when AC noise overlaps with a detection signal obtained by an ATR (concentration detecting means), caused by the influence of the application of a latent image development bias which includes an oscillating electric field, by detecting the overlap of the noise, eliminating the concentration detection influenced by the noise, ensuring the detection free of the influence of noise, and stably controlling the developer concentration at all times. CONSTITUTION:When the difference between the initial detection signal value Ref (1) of a reference light by the photodiode 16 of the ATR provided on a developing device 9 and the detection signal value Ref (2) after image formation on a first sheet is not ¦Ref(1)-Ref(2)¦ <=10H, the device judges that the detection was affected by noise, the indication of an error is displayed, and another sequence different from the image formation is carried out. Therefore, the concentration detection affected by noise is eliminated and the aim can be achieved. |
