| 摘要 |
PURPOSE:To always obtain a stable image by detecting a density of a test developed image which is different in potential difference between an electrostatic latent image and a developing means, comparing a variation rate calculated from said density with a standard variation rate set in advance, calculating the correct quantity of an image exposure, and executing the image exposure to a photosensitive body by its calculated exposure quantity. CONSTITUTION:A V-D curve in a state that an electrophotographic device is operated, namely, a V-D curve of a test image is derived. When an image of a test original picture 19a and 19b is formed in accordance with a sequence of a conventional method, a test image 17a and 17b whose density is different from each other are formed in a non-image part 16 provided on the way of the outside peripheral surface on a drum 1. An image density of the test image 17a and 17b is read by a sensor 18a and 18b, respectively, brought to digital conversion by an A/D22a and 22b, respectively, and read in a microcomputer 20. Subsequently, this density difference is derived, a variation rate M of the V-D curve is derived, and this variation rate M is compared with a reference variation rate stored in advance. |
