| 摘要 |
PURPOSE: To continue image forming operation even in the case failure is found out in sampling data by forming a gradation correction curve based on reflection density, storing a backup correction curve and selecting them so that exposure intensity may be controlled. CONSTITUTION: This device is provided with a write unit 400 forming plural patch latent images by exposing them on an image carrier 110, a developing device 130 developing the patch latent image, an image sensor C detecting the reflection density from the patch toner image obtained by developing the patch latent image, and a correction curve forming means forming the gradation correction curve based on the data on the reflection density. The exposure intensity of the write unit 400 is controlled in accordance with the curve. Then, the gradation correction curve used for the correction curve is stored, and when an abnormal value is found out in the data on the reflection density, the stored gradation correction curve is selected. Therefore, the image forming operation is continued even in the case the correction curve is not obtained because of the failure in the image density sensor C or in the midst of warming up. |
