| 摘要 |
PROBLEM TO BE SOLVED: To provide a developing device capable of maintaining the inside of a development tank at a predetermined inside pressure by restraining an increase in the pressure of the inside of the development tank, and to provide a process cartridge and an image forming apparatus. SOLUTION: A step 14e is formed around the exhaust port 10 of the development tank 14. A filter 11 is placed on the step 14e. The filter 11 is composed of: a first filter layer 11a with fine meshes; and a second filter layer 11b with coarse meshes, the underside of which is firmly fixed to the upper face of the first filter layer 11a and the pressure loss of which changes by the layer thickness. An edge frame 40, to which the upper face of the second filter layer 11b is firmly fixed, is placed on the filter 11 so as to be freely vertically movable. Tension springs 42 the end of each of which is locked to a corresponding support part 42 are attached to the left and right ends of the edge frame 40 so that the second filter layer 11b is pulled upward by the tension springs 41. Attached to the middle of the edge frame 40 is an actuating plate 43, which is vertically driven by a filter pressure loss changing means 104. COPYRIGHT: (C)2009,JPO&INPIT |
