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 developing apparatus includes an electrostatic latent image bearer, a developing sleeve, a case, and an air filter. The case accommodates a two-component developer and the developing sleeve. The air filter is attached to the case. The air filter has a thickness of 2 to 20 mm and has a density gradient with a pressure loss of 2 to 40 Pa at a wind speed of 10 cm/s. The air filter forms an airflow sucked into the case from a gap between the developing sleeve and the case and forms an airflow discharged from the case through the air filter. The two-component developer accommodated in the case contains a magnetic particle a surface of which is coated with a resin layer. The resin layer contains at least one type of chargeable particle.

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 process cartridge includes an image bearer, a developer bearer, and a positioning member. The image bearer is rotatable. The developer bearer is rotatable and opposite to the image bearer. The positioning member determines an opposing distance between the image bearer and the developer bearer, and includes a fitting portion and a groove. A fitted portion of the image bearer rotatably fits to the fitting portion. The groove extends from a ceiling portion to a bottom portion. A shaft portion of the developer bearer is slidingly movable in the groove. The groove is formed such that the shaft portion of the developer bearer contacts the bottom portion and is supported by the bottom portion. The ceiling portion of the groove is open upward so that the shaft portion of the developer bearer is insertable to and removable from the groove.

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 positioning member defines a facing distance between a first rotating body and a second rotating body. The positioning member includes a fitting portion, a groove, and a restricting member. A fitted portion of the first rotating body is to be rotatably fitted into the fitting portion. The groove has a groove shape extending in a predetermined direction from an opening to an abutting portion. A shaft portion of the second rotating body is to be slidably movable in the groove. The restricting member restricts movement of the shaft portion in the predetermined direction in a state in which the shaft portion abuts on the abutting portion in the groove. The restricting member is detachably disposed on the groove.

Abstract: A developing apparatus includes an electrostatic latent image bearer, a developing sleeve, a case, and an air filter. The case accommodates a two-component developer and the developing sleeve. The air filter is attached to the case. The air filter has a thickness of 2 to 20 mm and has a density gradient with a pressure loss of 2 to 40 Pa at a wind speed of 10 cm/s. The air filter forms an airflow sucked into the case from a gap between the developing sleeve and the case and forms an airflow discharged from the case through the air filter. The two-component developer accommodated in the case contains a magnetic particle a surface of which is coated with a resin layer. The resin layer contains at least one type of chargeable particle.

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 process cartridge includes an image bearer, a developer bearer, and a positioning member. The image bearer is rotatable. The developer bearer is rotatable and opposite to the image bearer. The positioning member determines an opposing distance between the image bearer and the developer bearer, and includes a fitting portion and a groove. A fitted portion of the image bearer rotatably fits to the fitting portion. The groove extends from a ceiling portion to a bottom portion. A shaft portion of the developer bearer is slidingly movable in the groove. The groove is formed such that the shaft portion of the developer bearer contacts the bottom portion and is supported by the bottom portion. The ceiling portion of the groove is open upward so that the shaft portion of the developer bearer is insertable to and removable from the groove.

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: An improved image forming apparatus includes an image bearer, a nip forming member, a transfer power source, and a controller. The controller switches a transfer mode between a first mode to transfer the toner image onto a first type sheet having a surface smoothness higher than a surface smoothness of a second type sheet and a second mode to transfer the toner image onto the second type sheet. The controller controls the transfer power source to output the transfer bias having an opposite-peak duty of greater than or equal to 50% that is a duty on the side of the opposite-peak value in the first mode. The controller controls the transfer power source to output the transfer bias having an opposite-peak duty of less than 50%, which is different from the opposite-peak duty of the first mode, in the second mode.

Abstract: An image forming apparatus includes a belt-shaped image bearer, a transferer, a guide, two rotators, and a support. The image bearer has an image bearing surface to bear an image thereon. The transferer forms a transfer section between the transferer and the image bearer, to transfer the image onto a recording medium. The guide is disposed upstream from the transfer section in a delivery direction of the recording medium, to guide the recording medium toward the transfer section. The two rotators are disposed upstream from the transfer section in a moving direction of the image bearer and in contact with a non-image bearing surface of the image bearer opposite to the image bearing surface, a first rotator being closer to the transfer section than a second rotator. The support supports the first rotator and the guide and adjusts a position of the first rotator and a position of the guide.

Abstract: An image forming apparatus includes an image bearer to bear a toner image, a nip forming member contacting the image bearer to form a transfer nip, and a transfer power source. The transfer bias has a transfer peak value to electrostatically move toner from the image bearer to the recording sheet and an opposite-peak value to electrostatically move less toner from the image bearer to the recording sheet than the transfer peak value. An opposite-peak duty of the transfer bias is less than 50%. The opposite-peak duty is tr/T×100% where T is one cycle of the transfer bias and tr is a time period during which the transfer bias is on a side of the opposite-peak value relative to an offset voltage of the transfer bias in the one cycle T.

Abstract: An image forming apparatus includes an image bearer, an intermediate transferor, a secondary transferor, a plurality of rotators including a secondary driving rotator, and a detector. The image bearer bears a detection image. The detection image is transferred from the image bearer to the intermediate transferor at a primary transfer position. The secondary transferor is looped around the plurality of rotators and disposed in contact with the intermediate transferor at a secondary transfer position where the detection image is transferred from the intermediate transferor to the secondary transferor. The secondary driving rotator drives the secondary transferor. The detector detects the detection image on the secondary transferor at a detection position. With this configuration, a distance from the secondary transfer position to the detection position on the secondary transferor is an integral multiple of a circumference of the secondary driving rotator.

Abstract: A belt device includes a belt unit including a plurality of rotators and a belt looped around the plurality of rotators. The belt device further includes a frame including a plurality of support portions to support the belt unit, a biasing member to bias the belt unit supported by the frame in a predetermined direction, and an adjuster to adjust a position of at least one of the plurality of support portions.

Abstract: An image forming apparatus includes an image bearer including a first image portion to bear a first toner image, a second image portion to bear a second toner image, and a non-image portion to bear an adjustment pattern. A transferor forms a transfer nip with the image bearer. A controller controls the power source to output an image bias as a transfer bias to transfer the first toner image and the second toner image onto a first recording medium and a second recording medium, respectively, in the transfer nip when the first image portion and the second image portion pass through the transfer nip and output a non-image bias as the transfer bias when the non-image portion passes through the transfer nip. The controller performs a constant current control on the image bias and performs a constant voltage control when the image bias switches to the non-image bias.