| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a developing device preventing decrease in an image density or occurrence of filming on a photoreceptor, by controlling temperature not only through a detecting result of temperature of a developing tank, but by taking a state of a toner external additive into consideration, and also to provide an image forming apparatus using the developing device. <P>SOLUTION: The developing device includes: a temperature sensor sensing the temperature of the developing tank; and a temperature control means controlling the sensed temperature. The device prevents decrease in an image density, sticking of a developer and occurrence of filming on a photoreceptor in such a way that: when an image area rate of a document to be printed is not more than 1%, the developing tank is cooled by the temperature control means; with the image area rate of 15% or more, the tank is not cooled; and with the image area rate from 2% to 14%, the tank is cooled only when the temperature of the developing tank is equal to or higher than the glass transition temperature (60°C) of the toner resin. <P>COPYRIGHT: (C)2011,JPO&INPIT |
