IMAGE FORMING DEVICE AND DEVELOPER STIRRING METHOD THEREOF

PROBLEM TO BE SOLVED: To obtain an image having stable printing density by stopping developer stirring operation when the leading edge of 2nd recording material does not reach a recording material detection means even though previously set time elapses after detecting the trailing edge of 1st recording material. SOLUTION: This device is provided with a measuring means such as a timer, etc., actuated based on the detection of the leading edge and the trailing edge of printing paper 9 by a paper sensor 21. The timer is constituted so that it may be cleared when the sensor 21 detects the leading edge of the paper 9 and it may start measurement when it detects the trailing edge of the paper, and starts to measure the previously set time when the trailing edge of the preceding paper passes through the sensor 21 and monitors whether the leading edge of the succeeding paper reaches the sensor 21 within the set time. When the leading edge of the succeeding paper does not reach the sensor 21 even though the set time elapses, the rotation of a developing roller 7a and an auger screw 7b is stopped, and the device stands by until the leading edge of the next printing paper reaches the sensor 21 under the condition where the stirring and mixing of developer is stopped.