| 摘要 |
PURPOSE:To form a clear image of high chromatic color and sufficient density for prolonged time and to effect image density control without compensation by using substantially equal spectral reflectance in a given wavelength range when developing a latent image on an image carrier by using plural kinds of toners. CONSTITUTION:The spectral reflectance of a plurality of, for example, three different color toners used for developing a latent image formed on the photosensitive drum has a wavelength range K of substantially equal spectral reflectance. When a density sensor 18 is used, the light 30 emitted by an LED18d passes through an optical passage 18b to be reflected by a reference image surface of the photosensitive drum 6 to fall on a phototransistor 18e via an optical passage 18b. The LED18d is so set that the peak wavelength range of the radiated light 30 included for instance the wavelength range K while the detection wavelength range is included within the wavelength range K. The detected density signal is supplied to a solenoid valve of the developer and the valve is opened or closed to start or stop toner supply from the hopper to control toner density. |
