| 摘要 |
PURPOSE:To improve the fixing property and stability of a copy, by grasping the optical density of the surface of an original by using an optical detecting means and controlling the temperature of a fixing device based on the grasped density information of the original surface. CONSTITUTION:A light from a halogen lamp 4 is reflected by an original surface 6 and a part of the reflected light is made incident to a CCD image sensor A. The light is converted into an electric signal at the image sensor A and inputted into a microcomputer through an integration circuit. When the integrated value is larger, the toner density on a transfer paper is high and, when the value is smaller, the toner density is low. At the time of ''copy on'' shown by A3 in the figure, the density information of the original surface is checked for a short time at pre-copying time T1 as shown by B3 and the electric power to a fixing device is immediately controlled to an adequate level as shown by P5 of the C3. Therefore, when the 1st transfer paper passes through the fixing device as shown by D3 of the graph, the temperature of the fixing device is set to an adequate level and adequate power control is performed for the following copies. As a result, the fixing property and stability can be improved. |
