| 摘要 |
PURPOSE:To readily perform the maintenance and control of the density of copy pictures wherein variation is compensated and which has high precision and stability by optically sensing the desity of the reference mark which is transferred to the outside of the copying area and by controlling the density of the copy pictures depending on the result of the sensing. CONSTITUTION:A density reference mark 23 is provided on the outside of the picture area of a transparent draft table 22 on which a draft is placed, and a density sensor 24 is provided on the outside of the picture area of a transfer belt 7 whose position conrresponds to the draft table 22. The density sensor 24 is constituted by a light emitting element 25 comprising an LED, an incandescent lamp, and the like, and a light-sensitive element 26 such as CDS cells, phototransistors, and the like. The light from the element 25 is relfected by a transferred reference mark 23a. The rate of reflection varies depending on the amount of toner deposition, and the different light currents are flown to the element 26, and the variation in currents is converted into the variation in voltages, thereby the amount of the toner deposition is sensed. In this way, the maintenance and control of the stable copy-picture density can be accomplished. |
