| 摘要 |
PURPOSE:To perform stable toner density control by an electrophotography type (two-component development) printer even if its photosensitive drum deteriorates and to prevent toner fogging and early deterioration of a developer. CONSTITUTION:This printer is provided with a toner mark 12a which is placed in good correlation between a toner mark output and toner density by discriminating a black-and-white ratio with a zigzag image, a toner mark 12E whose development reproducibility is secured with a solid black image, and a toner density control processing part 13 which compares voltage values, generated by reading, outputting, and converting the toner marks 12a and 12b, with a reference level. Consequently, the outputs of the two kind of toner marks are compared with the reference value to judge the deterioration state of the photosensitive drum 1, thereby performing the toner density control with the proper toner marks. |
