Abstract: An image forming apparatus includes an image carrier, a cleaning unit, a development device, and a control unit. The development device includes a toner collection mechanism having a developer carrier and a filter. The control unit is capable of executing a scattered toner recovery mode at non-image forming time, in which the filter is vibrated, a potential difference is generated in the direction for the toner to move from the developer carrier to the image carrier, the developer carrier is rotated in a reverse direction to that at image forming time, and the image carrier is rotated in the same direction as that at the image forming time, so that scattered toner, which has dropped from the filter and adhered to the developer carrier, is recovered by the cleaning unit via the image carrier.

Abstract: An image forming apparatus includes a development device, and a control unit that controls the development device. The development device includes a toner collection mechanism having a duct, a filter, and an exhaust fan. The duct is connected to a conveyance chamber of the development container and allows air in the conveyance chamber to flow through. The filter is disposed at a connecting part between the duct and the conveyance chamber, and collects toner flowing into the duct from the conveyance chamber. The exhaust fan makes the air in the conveyance chamber flow to the outside via the duct. The control unit changes rotational frequency or operation frequency of the exhaust fan based on current detected by a current detection unit at non-image forming time.

Abstract: Provided is an image forming apparatus in which, while image formation is prevented from being performed, scattered toner that has dropped from a filter and adhered to an outer peripheral surface of a developer carrying member is recovered. A fixed magnet of the developer carrying member has a first pole that is arranged to face the filter, and a second pole and a third pole on a downstream side relative to the first pole. The first pole and the second pole have polarities opposite to each other, and the second pole and the third pole have a same polarity. A length of a gap between the developing container and an area where the developing sleeve faces the second pole among areas of the developing sleeve is smaller than a length between the developing sleeve and the filter.

Abstract: Provided is an image forming apparatus in which, while image formation is prevented from being performed, scattered toner that has dropped from a filter and adhered to an outer peripheral surface of a developer carrying member is recovered by a cleaning unit through intermediation of an image bearing member. An absolute value of a perpendicular-magnetic-force gradient of a fixed magnet of the developer carrying member is 4.0 mT/° or less at a position where the fixed magnet faces a central portion of the filter in a rotation direction of a developing sleeve.

Abstract: An image forming apparatus includes a development device, and a control unit that controls the development device. The development device includes a toner collection mechanism having a duct, a filter, and an exhaust fan. The duct is connected to a conveyance chamber of the development container and allows air in the conveyance chamber to flow through. The filter is disposed at a connecting part between the duct and the conveyance chamber, and collects toner flowing into the duct from the conveyance chamber. The exhaust fan makes the air in the conveyance chamber flow to the outside via the duct. The control unit changes rotational frequency or operation frequency of the exhaust fan based on current detected by a current detection unit at non-image forming time.

Abstract: Provided is an image forming apparatus that is capable of carrying out a scattered-toner recovery mode in which, while image formation is prevented from being performed, scattered toner that has dropped from a filter and adhered to an outer peripheral surface of a developer carrying member is recovered by a cleaning unit through intermediation of an image bearing member. A fixed magnet of the developer carrying member has a first pole that faces the image bearing member, a second pole that faces the filter, and an intermediate pole between the first pole and the second pole.

Abstract: An image forming apparatus includes an image carrier, a cleaning unit, a development device, and a control unit. The development device includes a toner collection mechanism having a developer carrier and a filter. The control unit is capable of executing a scattered toner recovery mode at non-image forming time, in which the filter is vibrated, a potential difference is generated in the direction for the toner to move from the developer carrier to the image carrier, the developer carrier is rotated in a reverse direction to that at image forming time, and the image carrier is rotated in the same direction as that at the image forming time, so that scattered toner, which has dropped from the filter and adhered to the developer carrier, is recovered by the cleaning unit via the image carrier.

Abstract: A processor causes a printing portion to execute test image transfer processing for transferring a plurality of test toner images onto an area outside a secondary transfer area on a surface of an intermediate transfer member, and secondary voltage stop processing for stopping a supply of a secondary transfer voltage. The processor acquires a plurality of first sensing densities. The processor causes the printing portion to execute the test image transfer processing and secondary voltage supply processing for supplying the secondary transfer voltage. The processor acquires a plurality of second sensing densities. The processor compares the plurality of first sensing densities and the plurality of second sensing densities to determine a state of a toner charging amount in each of the plurality of test toner images.

Abstract: An image forming apparatus includes a toner charge amount predictor, a toner developing resistance calculator, and a determiner. The toner developing resistance calculator calculates a toner developing resistance on the basis of a bias voltage applied to a developing device and a measured developing current by dividing a value of the bias voltage by a value of the developing current when a developing device develops an electrostatic latent image formed on the surface of an image carrier to form a toner image. The toner charge amount predictor predicts a toner charge amount of a toner which is supplied to the image carrier by the developing device on the basis of a density of the toner image and the developing current. The determiner determines a state of the developing device on the basis of the toner charge amount and the toner developing resistance.

Abstract: An image forming apparatus includes a plurality of image forming units, a developing voltage power supply, a density detection device, a current detection unit, and a control unit. The plurality of image forming units form an image and substantially same development conditions are set to evenly divide an image density among the image forming units. The control unit detects whether there is an anomaly in a developing device, based on a toner charge amount calculated based on a DC component of developing current when a reference image is formed on an image carrier by each of the developing devices and a density of the reference image. When an anomaly is detected in any of the developing devices, the control unit inhibits use of the image forming unit including the developing device, and resets the development conditions to evenly divide the image density among the usable image forming units.

Abstract: An image forming apparatus includes a plurality of image forming units, a developing voltage power supply, a density detection device, a current detection unit, and a control unit. The plurality of image forming units form an image and substantially same development conditions are set to evenly divide an image density among the image forming units. The control unit detects whether there is an anomaly in a developing device, based on a toner charge amount calculated based on a DC component of developing current when a reference image is formed on an image carrier by each of the developing devices and a density of the reference image. When an anomaly is detected in any of the developing devices, the control unit inhibits use of the image forming unit including the developing device, and resets the development conditions to evenly divide the image density among the usable image forming units.

Abstract: An image forming apparatus includes a toner charge amount predictor, a toner developing resistance calculator, and a determiner. The toner developing resistance calculator calculates a toner developing resistance on the basis of a bias voltage applied to a developing device and a measured developing current by dividing a value of the bias voltage by a value of the developing current when a developing device develops an electrostatic latent image formed on the surface of an image carrier to form a toner image. The toner charge amount predictor predicts a toner charge amount of a toner which is supplied to the image carrier by the developing device on the basis of a density of the toner image and the developing current. The determiner determines a state of the developing device on the basis of the toner charge amount and the toner developing resistance.

Abstract: An image forming apparatus includes a storage unit and a charging amount acquisition unit. The charging amount acquisition unit forms a measurement toner image on the image carrier while changing the frequency of the alternating current voltage of the development bias, acquires a tilt of a measurement straight line representing a relationship between the change amount of the frequency and a density change amount of the measurement toner image based on the change amount of the frequency and a result of detecting density of the measurement toner image in the density detecting unit, and acquires the charging amount of the toner based on the acquired tilt of the measurement straight line and the reference information in the storage unit.

Abstract: In the first charge amount acquisition operation, based on density of a plurality of toner images for measurement or based on a direct component of a developing current at the time of forming the plurality of toner images in addition to the density of the plurality of toner images for measurement, the charge amount acquisition section acquires a first toner charge amount that is a charge amount of toner included in the toner image for measurement. In the second charge amount acquisition operation, based on the toner density detected at the time of image formation and a relationship between the first toner charge amount and the toner density detected in the first charge amount acquisition operation, the charge amount acquisition section acquires a second toner charge amount that is a charge amount of the toner in the development device.

Abstract: In the first charge amount acquisition operation, based on density of a plurality of toner images for measurement or based on a direct component of a developing current at the time of forming the plurality of toner images in addition to the density of the plurality of toner images for measurement, the charge amount acquisition section acquires a first toner charge amount that is a charge amount of toner included in the toner image for measurement. In the second charge amount acquisition operation, based on the toner density detected at the time of image formation and a relationship between the first toner charge amount and the toner density detected in the first charge amount acquisition operation, the charge amount acquisition section acquires a second toner charge amount that is a charge amount of the toner in the development device.

Abstract: An image forming apparatus has an image carrier, an electrifying member, and a charge eliminating device, and eliminates remaining charge on the surface of the image carrier by the charge eliminating device. The charge eliminating device includes a discharge member. The discharge member includes an electro conductive knit fabric knitted in a cylindrical shape using twisted yarn made of twisted metal fibers and a support member having a cylindrical shape and inserted in the electro conductive knit fabric, and is disposed to face the image carrier in a noncontact manner. A magnet member is disposed inside the image carrier within a charge elimination nip width between two tangential lines of an outer circumference surface of the discharge member, the two tangential lines being parallel to a straight line passing through a rotation center of the image carrier and a center axis of the discharge member.

Abstract: An image forming apparatus includes a storage unit and a charging amount acquisition unit. The charging amount acquisition unit forms a measurement toner image on the image carrier while changing the frequency of the alternating current voltage of the development bias, acquires a tilt of a measurement straight line representing a relationship between the change amount of the frequency and a density change amount of the measurement toner image based on the change amount of the frequency and a result of detecting density of the measurement toner image in the density detecting unit, and acquires the charging amount of the toner based on the acquired tilt of the measurement straight line and the reference information in the storage unit.

Abstract: A developing device includes a developing container, a first stirring and conveying member, a second stirring and conveying member, a developer replenishing port, a developer discharging portion, a developing roller, a toner supply roller, a regulating blade, a toner receiver member, and a vibration generating device. The developing device is capable of executing a toner collecting mode in which the vibration generating device vibrates the toner receiver member so that toner deposited on the toner receiver member is shaken off by vibration and is collected into the second conveying chamber, in the non-image formation period. The developing device is capable of executing a forced discharge mode in which developer containing the collected toner collected from the toner receiver member into the second conveying chamber is forcibly discharged from the developer discharging portion to outside of the developing container, after the toner collecting mode is executed.

Abstract: A developing device includes a developing container, a first stirring and conveying member, a second stirring and conveying member, a developer replenishing port, a developer discharging portion, a developing roller, a toner supply roller, a regulating blade, a toner receiver member, and a vibration generating device. The developing device is capable of executing a toner collecting mode in which the vibration generating device vibrates the toner receiver member so that toner deposited on the toner receiver member is shaken off by vibration and is collected into the second conveying chamber, in the non-image formation period. The developing device is capable of executing a forced discharge mode in which developer containing the collected toner collected from the toner receiver member into the second conveying chamber is forcibly discharged from the developer discharging portion to outside of the developing container, after the toner collecting mode is executed.

Abstract: In an image forming device including a volume supply type developing device, generation of an aggregate of a developer on a back surface of a layer thickness regulating member is suppressed, while occurrence of an image failure caused by the aggregate is suppressed. An image forming device includes: a photosensitive drum; a developing device including a developing roller; a toner container including a toner sensor; and a control portion. According to an increase or decrease of a retention part formed in a first transport path, a toner flows into the developing device from the toner container. The control portion causes the developing roller to reversely rotate at predetermined timing when the toner sensor senses that a residual amount of a toner in the toner container falls below a predetermined threshold value.