Patent ID: 8285178
Filing Date: 2012-10-09
Classification: G03G

Abstract:
1. An image forming apparatus including an image bearing member, a developing device that supplies the image bearing member with toner contained in a two-component developer, and a toner supply device that supplies the developing device with toner, the developing device comprising: a developing roller; a developing container in which the two-component developer is stored, the developing container having a partition member that is used for dividing an internal space of the developing container into a first compartment and a second compartment and that extends along an axial direction of the developing roller; and a conveying member, installed in the first and second compartments, which agitates and conveys the two-component developer, the developing roller supplying the image bearing member with toner contained in a two-component developer stored in the second compartment, the first and second compartments being communicated with each other through a first communicating path at one end of the axial direction and through a second communicating path at the other end of the axial direction, the partition member having a third communicating path, provided between the first and second communicating path, through which the first and second compartments are communicated with each other, the developing container including an upper wall covering the first compartment, a first toner density detecting sensor provided between the first communicating path and the third communicating path in the second compartment, and a second toner density detecting sensor provided between the second communicating path and the third communicating path in the second compartment, the upper wall having one toner supply opening, provided in a higher position than a portion of the first compartment that faces the third communicating path, which is used for receiving the toner that is supplied from the toner supply device, the conveying member conveying the two-component developer on (i) a first route of circulation leading from the third communicating path to the first communicating path in the first compartment and further leading from the first communicating path to the third communicating path in the second compartment and (ii) a second route of circulation leading from the third communicating path to the second communicating path in the first compartment and further leading from the second communicating path to the third communicating path in the second compartment, the image forming apparatus including a toner supply switching section that chooses, in accordance with toner densities detected by the first and second toner density detecting sensors, whether the toner that is supplied from the toner supply device is guided into the first or second route of circulation, the toner supply device is located above the toner supply opening of the developing container, and the toner supply switching section includes (i) a guide plate, installed in a center of the toner supply opening, which is able to rotate on an axis of rotation perpendicular to a direction of conveyance of the two-component developer in the first compartment and which is parallel to the axis of rotation and (ii) a guide plate displacement member that causes the guide plate to be inclined at either a first position of inclination where an upper end of the guide plate is located toward the second communicating path and a lower end of the guide plate is located toward the first communicating path, or a second position of inclination where the upper end is located toward the first communicating path and the lower end is located toward the second communicating path.