| 摘要 |
PROBLEM TO BE SOLVED: To detect the end of toner with high accuracy without making the constitution of a device complicated by detecting the presence of replenishment toner based on the result of discrimination with density decrease and increase discriminating means. SOLUTION: An electrostatic latent image of a detecting reference pattern is formed on a photoreceptor, then, the pattern is developed and the image density of the developed reference pattern is detected by an optical sensor 205 as an image density detecting means. A CPU 500A controls a driving part for supplying toner 504, based on the result of the detection, to execute control for making the concn. of the toner in a developing unit a fixed one. In other words, the decrease of the density is discriminated, that is, whether the image density of the developed reference pattern becomes lower than a fixed one or not is discriminated and the increase of the image density of the developed reference pattern caused by the supply of the toner by a toner supplying means is discriminated, from the result of the detection by the optical sensor 205, so that the presence of the replenishment toner is detected by the result of the discrimination of the decrease and increase of the density, to detect the end of the toner. |
