Image forming apparatus

An image forming apparatus comprising:

• a plurality of image forming units that include a photosensitive drum being able to rotate about a horizontally extending drum axis and a developing device supplying toner to the photosensitive drum, and to be arranged along an arrangement direction horizontally orthogonal to the drum axis;
• and
• a plurality of toner replenishment units provided corresponding to each of the plurality of image forming units and that replenish toner to the developing device, each of the plurality of toner replenishment units comprising:
• first and second containers being able to store toner inside and discharge the toner;
• a first vertical conveyance pipe formed in a tubular shape having a peripheral wall surrounding a first vertical pipe axis extending vertically downward from the first container and that guides the toner discharged from the first container vertically downward along the first vertical pipe axis;
• a second vertical conveyance pipe formed in a tubular shape having a peripheral wall surrounding a second vertical pipe axis extending vertically downward from the second container and that guides the toner discharged from the second container vertically downward along the second vertical pipe axis;
• a first horizontal conveyance pipe formed in a tubular shape extending in a first horizontal direction intersecting the drum axis and the arrangement direction and including a first inflow port connected to a lower end of the first vertical conveyance pipe for toner to flow in;
• a second horizontal conveyance pipe formed in a tubular shape extending in a second horizontal direction at an acute angle with respect to the first horizontal direction and including a second inflow port connected to a lower end of the second vertical conveyance pipe for toner to flow in;
• a first conveyance member disposed in the first horizontal conveyance pipe so as to be able to rotate about a first horizontal rotation axis along the first horizontal direction, and to convey the toner that has flowed into the first horizontal conveyance pipe through the first inflow port to a downstream side by rotation;
• a second conveyance member disposed in the second horizontal conveyance pipe so as to be able to rotate about a second horizontal rotation axis along the second horizontal direction, and to convey the toner that has flowed into the second horizontal conveyance pipe through the second inflow port to a downstream side by rotation;
• a confluence section that communicates with a downstream side portion of the first horizontal conveyance pipe and a downstream side portion of the second horizontal conveyance pipe respectively, to receive the toner conveyed by the first conveyance member and the second conveyance member respectively inside, and to include a confluence discharge port discharging the received toner;
• a third vertical conveyance pipe formed in a tubular shape having a peripheral wall surrounding a third vertical pipe axis extending vertically downward from the confluence discharge port and that guides the toner discharged from the confluence section through the confluence discharge port toward the developing device vertically downward along the third vertical pipe axis;
• and
• a conveyance driver that generates a driving force to rotate the first conveyance member and the second conveyance member,
• wherein in a plan view of the confluence section seen from a vertical direction, the confluence discharge port is disposed between the first horizontal rotation axis and the second horizontal rotation axis,
• wherein a first inter-axis distance between the first horizontal rotation axis and the third vertical pipe axis and a second inter-axis distance between the second horizontal rotation axis and the third vertical pipe axis are set to a same value, and
• wherein the first vertical conveyance pipe or the third vertical conveyance pipe of each of the plurality of toner replenishment units is disposed at a different position in a direction along the drum axis.

An image forming apparatus comprising:

• at least three image forming units that includes a photosensitive drum being able to rotate about a horizontally extending drum axis and a developing device supplying toner to the photosensitive drum, and to be arranged along an arrangement direction horizontally orthogonal to the drum axis;
• and
• at least three toner replenishment units provided corresponding to each of the at least three image forming units and that replenish toner to the developing device, each of the at least three toner replenishment units comprising:
• first and second containers being able to store toner inside and discharge the toner;
• a first vertical conveyance pipe formed in a tubular shape having a peripheral wall surrounding a first vertical pipe axis extending vertically downward from the first container and that guides the toner discharged from the first container vertically downward along the first vertical pipe axis;
• a second vertical conveyance pipe formed in a tubular shape having a peripheral wall surrounding a second vertical pipe axis extending vertically downward from the second container and that guides the toner discharged from the second container vertically downward along the second vertical pipe axis;
• a first horizontal conveyance pipe formed in a tubular shape extending in a first horizontal direction intersecting the drum axis and the arrangement direction and including a first inflow port connected to a lower end of the first vertical conveyance pipe for toner to flow in;
• a second horizontal conveyance pipe formed in a tubular shape extending in a second horizontal direction at an acute angle with respect to the first horizontal direction and including a second inflow port connected to a lower end of the second vertical conveyance pipe for toner to flow in;
• a first conveyance member disposed in the first horizontal conveyance pipe so as to be able to rotate about a first horizontal rotation axis along the first horizontal direction, and to convey the toner that has flowed into the first horizontal conveyance pipe through the first inflow port to a downstream side by rotation;
• a second conveyance member disposed in the second horizontal conveyance pipe so as to be able to rotate about a second horizontal rotation axis along the second horizontal direction, and to convey the toner that has flowed into the second horizontal conveyance pipe through the second inflow port to a downstream side by rotation;
• a confluence section that communicates with a downstream side portion of the first horizontal conveyance pipe and a downstream side portion of the second horizontal conveyance pipe respectively, receives the toner conveyed by the first conveyance member and the second conveyance member respectively inside, and includes a confluence discharge port discharging the received toner;
• a third vertical conveyance pipe formed in a tubular shape has a peripheral wall surrounding a third vertical pipe axis extending vertically downward from the confluence discharge port and guides the toner discharged from the confluence section through the confluence discharge port toward the developing device vertically downward along the third vertical pipe axis;
• and
• a conveyance driver that generates a driving force to rotate the first conveyance member and the second conveyance member,
• wherein in a plan view of the confluence section seen from a vertical direction, the confluence discharge port is disposed between the first horizontal rotation axis and the second horizontal rotation axis,
• wherein a first inter-axis distance between the first horizontal rotation axis and the third vertical pipe axis and a second inter-axis distance between the second horizontal rotation axis and the third vertical pipe axis are set to a same value, and
• wherein in the at least three toner replenishment units, a pitch between the first vertical conveyance pipes adjacent to each other in the arrangement direction or a pitch between the third vertical conveyance pipes in the arrangement direction is set to a different value.