| 摘要 |
PURPOSE:To attain color reproduction with stable and excellent picture quality by generating a reference gradation signal with a diagnostic command signal and applying gradation correction with an output processing its signal. CONSTITUTION:When a test mode switch 165 is turned on, the diagnostic command signal is generated, lighting lamps 5, 6 are moved along an original 1, then a test chart 4 is scanned and image pickup elements 14, 16, 18 generate three color reference signals of blue B, green G and red R, respectively. Outputs of the elements 14, 16, 18 are subjected to prescribed processing at an image processor 27, laser light from a semiconductor laser 21 scans a photosensitive drum 24 via a polygon mirror 22 to form an electrostatic latent image on the drum 24. This latent image is transferred on a sheet of copy paper 48 wound on a transfer drum 53. The image on the chart 4 tranferred on the copy paper is read by a photo sensor unit 170 and the gradation is corrected by four phototransistors sensing the pattern with different gradation difference. |
