| 摘要 |
PURPOSE:To always keep the image density at a proper value by providing a spectral reflection area of a standard card plate in a position other than the effective spectral absorption area of a photosensitive body. CONSTITUTION:The image of a standard card plate 4 provided on an original platen 10 is projected to a photosensitive body 1 through an optical system 3, and a formed electrostatic latent image is developed to form a toner image, and the optical density of this toner image is measured to control the toner concentration of the developer. In this case, the spectral reflection area of the standard card plate 4 is provided in a position other than the effective spectral absorption area of the photosensitive body 1. Thus, the toner concentration of the developer is kept constant through the device is continuously operated for a long time, and as the result, the image density is always kept at a proper value. |
