| 摘要 |
PURPOSE:To always hold correctly the density of the part corresponding to the part of the ground color of an original by comparing concentration/density of the ground color part before/after a transfer of transfer paper and correcting the concentration setting condition in accordance with a difference of both of them. CONSTITUTION:When a copy processing is started, the concentration of transfer paper before a transfer is detected by a signal from a before-transfer concentration sensor S2 at about the same time as a density detection of a document. In this case, simultaneously, a peak value of the density is held. When the transfer paper is further carried continuously, it passes through the lower part of an after-transfer density sensor S3, the density of the transfer paper after a transfer is detected, and simultaneously, a peak value of a density signal is held. Subsequently, when copying is continued, the peak values obtained from the respective signals of the sensor S2 and S3 are compared, and its difference is calculated. When it is decided that the difference of the peak values exceeds a prescribed allowable value, an exposure adjusting procedure is suspended and the concentration setting condition is varied in the direction in which the image density becomes thin. In such a way, a beautiful copy can always be obtained. |
