| 摘要 |
PURPOSE:To ameliorate the shortage of toner concentration in a developing device and to reduce toner consumption caused by the detection of the toner concentration in excessive frequencies by providing a timing control means for allowing a developing pattern forming means to form a developing pattern image every time the number of recorded sheets attains the number set by a numerical value setting means. CONSTITUTION:The numerical value setting means 210 sets a small number when a recording size is large and a large number when the recording size is small and the timing control means 210 has the developing pattern image formed every time the number of recorded sheets attains the set number. A pattern density sensor 18P detects recording density and the toner supply control means 210 allows a toner supply means 17 to supply the toner when the detection density is low corresponding to the detection density. Therefore, when the recording size is large, the density of the developing pattern is detected every small number of sheets, so that the toner is rapidly replenished corresponding to high-speed toner consumption in the developing device. Thus, the stable recording density is obtained and the toner consumption in the case of detecting the density of the developing pattern is reduced by detecting the density of the developing pattern every large number of sheets when the recording size is small. |
