| 摘要 |
PURPOSE:To obtain the proper density of a first toner image by estimating the scraping quantity of the first toner image by a second developer and setting developing conditions presuming the scraping quantity. CONSTITUTION:Two developing units 4 and 6 having the toner of different colors, respectively are both set in a developing state to generate a toner sticking quantity detecting pattern. Its toner sticking quantity is detected by a toner sticking quantity detecting sensor 61 and the data of the detection is stored in memory. Constinuously, only a first developing uni 4 is diven to generate the oner sicking quatitydete detectin pattern. Its toner sticking quantity is detected b the sensor 61 and stored in the memory. Continuously, the difference between the toner sticking quantities obtained in the driving states of the developing units 4 and 6 and that obtained by driving only the developing unit 4 is obtained so that a toner scraping quantity by the second developer is estimated. The developing conditions of the first and second developing units 4 and 6 are determined based on the toner scraping quantity. |
