Abstract: A filter holding device includes an opening portion and a filter. The opening portion communicates an inside of the filter holding device with an outside of the filter holding device. The filter includes a first side and a second side. The first side faces the inside of the filter holding device. The second side faces the outside of the filter holding device. The filter has a lower weight density per unit volume at the first side than at the second side. At least a side face of the first side of the filter is covered with an air-impermeable member. The side face is a lateral face of the filter at the first side.

Abstract: A filter holding device includes an opening portion and a filter. The opening portion communicates an inside of the filter holding device with an outside of the filter holding device, and has a rim that extends in a communication direction from the inside of the filter holding device toward the outside of the filter holding device. The filter is disposed in the opening portion, and has a first side and a second side. The first side faces the inside of the filter holding device. The second side faces the outside of the filter holding device. The filter has a larger weight density per unit volume at the second side facing the outside of the filter holding device than at the first side facing the inside of the filter holding device in a state in which the filter is disposed in the opening portion.

Abstract: A developing device includes a developing case, a filter, and a filter holder. The developing case stores developer inside to develop a latent image formed on a surface of an image bearer and has an opening portion that communicates between an inside and an outside of the developing device. The filter has a lower weight density per unit volume at a first side of the filter facing the inside of the developing device than a weight density per unit volume at a second side of the filter facing the outside of the developing device. The filter holder is detachably attached to the opening portion of the developing case with the filter held by the filter holder.

Abstract: A filter holding device includes an opening portion and a filter. The opening portion communicates between an inside and an outside of the filter holding device. The filter is disposed in the opening portion and includes a first side and a second side. The first side is located adjacent to the inside of the filter holding device. The second side is located adjacent to the outside of the filter holding device. The filter has a larger weight density per unit volume at the second side than a weight density per unit volume at the first side and has a larger area of a surface intersecting a communication direction at the second side than an area of a surface intersecting the communication direction at the first side.

Abstract: A filter includes a sticker and a filter body. The filter body has a smaller weight density per unit volume at a first side than at a second side opposite the first side. The sticker is disposed around a surface of the second side of the filter body.

Abstract: A filter holding device includes an opening portion and a filter. The opening portion communicates an inside of the filter holding device with an outside of the filter holding device. The filter includes a first side and a second side. The first side faces the inside of the filter holding device. The second side faces the outside of the filter holding device. The filter has a lower weight density per unit volume at the first side than at the second side. At least a side face of the first side of the filter is covered with an air-impermeable member. The side face is a lateral face of the filter at the first side.

Abstract: An image forming apparatus includes an image bearer, a rotation shaft, a developing device, and a supply portion. The developing device includes a developing device main portion that rotates around the rotation shaft between a developing position and a retracted position and includes a developer, a developer bearer to face or be away from the image bearer depending on whether the developing device main portion is at the developing position or the retracted position, a replenishment portion having a replenishment port with an opposite surface formed by an arc drawn around the rotation shaft to replenish the developer, and a non-rotating portion. The supply portion has a supply port with an opposite surface formed by an arc drawn around the rotation shaft and facing the opposite surface of the replenishment port. The supply port communicates the replenishment port and supplies the developer to the developing device through the replenishment port.

Abstract: A developing device includes a developer conveyer, a bearing, a flange, and a developer mover. The developer conveyer is rotatable and configured to convey a developer. The bearing rotatably supports a support shaft of the developer conveyer. The flange is disposed at an end portion of the developer conveyor to regulate a movement of the developer in an axial direction of the developer conveyer. The developer mover is disposed on a surface of the flange facing the bearing and configured to move the developer that enters between the flange and the bearing.

Abstract: An image forming apparatus includes an image bearer, a rotation shaft, a developing device, and a supply portion. The developing device includes a developing device main portion that rotates around the rotation shaft between a developing position and a retracted position and includes a developer, a developer bearer to face or be away from the image bearer depending on whether the developing device main portion is at the developing position or the retracted position, a replenishment portion having a replenishment port with an opposite surface formed by an arc drawn around the rotation shaft to replenish the developer, and a non-rotating portion. The supply portion has a supply port with an opposite surface formed by an arc drawn around the rotation shaft and facing the opposite surface of the replenishment port. The supply port communicates the replenishment port and supplies the developer to the developing device through the replenishment port.

Abstract: A developing device includes a developer conveyer, a bearing, a flange, and a developer mover. The developer conveyer is rotatable and configured to convey a developer. The bearing rotatably supports a support shaft of the developer conveyer. The flange is disposed at an end portion of the developer conveyor to regulate a movement of the developer in an axial direction of the developer conveyer. The developer mover is disposed on a surface of the flange facing the bearing and configured to move the developer that enters between the flange and the bearing.