Patent ID: 8948658
Filing Date: 2015-02-03
Classification: G03G

Abstract:
1. A developing device comprising: a first developer conveyance path and a second developer conveyance path for conveying and circulating a two-component developer including a toner and a magnetic carrier; a first communicating path for guiding the two-component developer in the first developer conveyance path to the second developer conveyance path; a second communicating path for guiding the two-component developer in the second developer conveyance path to the first developer conveyance path; a first conveyance member being provided in the first developer conveyance path in a freely rotatable manner and having a helical blade for conveying the two-component developer in one direction, the helical blade having helical pitches decreasing toward a downstream side from an upstream side of a developer conveyance direction; a second conveyance member being provided in the second developer conveyance path in a freely rotatable manner for conveying the two-component developer in one direction; a developing roller for bearing and supplying the two-component developer in the first developer conveyance path to a photoconductor drum; a developer collection path for guiding the two-component developer left on a surface of the developing roller after the developer is supplied to the photoconductor drum in a direction away from the first developer conveyance path; a third developer conveyance path for containing the two-component developer guided to the developer collection path and conveying the developer in one direction; a third conveyance member being provided in the third developer conveyance path in a freely rotatable manner; a third communicating path for guiding the two-component developer in the third developer conveyance path to the second developer conveyance path; and a developer surface adjustment window being provided between the first developer conveyance path and the developer collection path and having a predetermined level for allowing excess developer exceeding the level of the window to be guided from the first developer conveyance path to the developer collection path.