Image forming apparatus including toner conveyance detection portion detecting toner conveyance error in toner conveyance

An image forming apparatus, comprising:

• a developing device that supplies toner to an image carrier;
• a container that contains the toner to be replenished to the developing device;
• a toner replenishment device that includes a plurality of toner replenishment paths through which the toner in the container is conveyed and replenished to the developing device;
• a toner conveyance detection portion that detects a toner conveyance error in toner conveyance performed by using the plurality of toner replenishment paths;
• and
• a control portion that controls operations of the developing device and the toner replenishment device,
• wherein
• in a case where the toner conveyance detection portion has detected the toner conveyance error in one of the toner replenishment paths that is in use, the control portion switches to another one of the toner replenishment paths to convey the toner,
• the toner conveyance detection portion includes a toner amount detection portion that detects a toner amount in the developing device, in the container, and in the plurality of toner conveyance paths,
• the toner amount detection portion includes
• a developing toner amount detection portion that detects the toner amount by detecting a toner concentration in the developing device, and
• an intermediate toner amount detection portion that detects the toner amount on the toner replenishment paths, and
• in a case where the control portion has detected that the toner amount is smaller than a predetermined value by means of the developing toner amount detection portion and has also detected that the toner amount is larger than a predetermined value by means of the intermediate toner amount detection portion, the control portion determines that the toner conveyance error has occurred in one of the toner replenishment paths that is in use.

An image forming apparatus, comprising:

• a developing device that supplies toner to an image carrier;
• a container that contains the toner to be replenished to the developing device;
• a toner replenishment device that includes a plurality of toner replenishment paths through which the toner in the container is conveyed and replenished to the developing device;
• a toner conveyance detection portion that detects a toner conveyance error in toner conveyance performed by using the plurality of toner replenishment paths;
• and
• a control portion that controls operations of the developing device and the toner replenishment device,
• wherein
• in a case where the toner conveyance detection portion has detected the toner conveyance error in one of the toner replenishment paths that is in use, the control portion switches to another one of the toner replenishment paths to convey the toner,
• the toner conveyance detection portion includes a first toner amount detection portion and a second toner amount detection portion that detect toner amounts, corresponding to mutually different positions, with respect to the toner conveyed from the container to the developing device,
• the second toner amount detection portion detects the toner amount corresponding to a position upstream of the first toner amount detection portion in a toner conveying direction of one of the toner supply paths that is in use, and
• in a case where the control portion has detected that the toner amount is smaller than a predetermined value by means of the first toner amount detection portion and has also detected that the toner amount is larger than a predetermined value by means of the second toner amount detection portion, the control portion determines that the toner conveyance error has occurred in one of the toner replenishment paths that is in use.