Developing device and image forming apparatus

A developing device comprising:

• a development container which includes a first conveyance chamber and a second conveyance chamber placed in parallel juxtaposition and communicated with each other at their longitudinal both end portions and in which a toner-containing developer to be fed to an image carrier is contained;
• a first conveyance member and a second conveyance member which are rotatably supported by the first conveyance chamber and the second conveyance chamber, respectively, and which convey and circulate the developer, while stirring the developer, in mutually opposite directions of the longitudinal direction;
• a developer carrier which is rotatably supported by the development container in opposition to the image carrier, and which feeds the toner contained in the second conveyance chamber to the image carrier;
• and
• a toner trapping mechanism for trapping the toner contained in the second conveyance chamber, wherein
• the toner trapping mechanism includes:
• a duct which is connected to the second conveyance chamber and which allows air present in the second conveyance chamber to flow therethrough;
• an air inlet port which is opened at a connecting portion between the duct and the second conveyance chamber and which allows air present in the second conveyance chamber to flow into the duct;
• a trapping filter which traps the toner contained in air flowing through the duct;
• and
• a fan which allows air present in the second conveyance chamber to be sucked into the duct and let to flow outside, and
• the development container has an air vent which is opened in the first conveyance chamber and which is communicated with outside of the development container.