Disclosed is a developing device including a conveying screw and an inductance sensor. The inductance sensor includes a detector detecting magnetic permeability of developer and has such detection sensitivity that the detection sensitivity with which the detector detects magnet permeability when magnetic material is 1 mm away from the detector in a vertical direction is 10% or more of that when magnetic material is on the detector. The conveying screw includes a first portion having a first rotary shaft and a first blade and a second portion having a second rotary shaft and a second blade. The first portion is opposite the detector with respect to a conveying direction of the conveying screw. The second portion is downstream of a downstream end of the detector in the conveying direction within one pitch of the first blade. The second rotary shaft diameter is greater than the first rotary shaft diameter.

In various examples, colorant sensors can include a printing device comprising a hopper to receive a colorant, a supply to receive the colorant from the hopper, an aperture disposed between the hopper and the supply, a light emitter to emit light that passes through the aperture, and a light sensor located on the opposite side of the aperture relative the light emitter to sense a portion of the emitted light that passes through the aperture to permit determination of whether colorant present in the aperture based on the portion of the emitted light sensed by the light sensor.

According to one embodiment, an image forming apparatus includes a developing device, a sensor, a control information obtaining unit, and a control unit. The developing device forms an image on an image carrier using a developer. The sensor generates a signal indicating a measurement value related to the developer. The control information obtaining unit obtains, as control information of the developing device, one or more pieces of the control information pre-associated with the measurement value, from a recording medium associated with the developer. The control unit selects the control information associated with the measurement value indicated by the signal, from the one or more pieces of control information obtained from the recording medium. The control unit controls an operation of the developing device based on the selected control information.

An image forming apparatus includes a frame, a drum cartridge mountable to the frame, and including a photosensitive drum and a drum memory in which drum identification information identifying the drum cartridge is stored, and a control unit including a main body memory in which the drum identification information is to be stored. The control unit reads out the drum identification information from the drum memory, determines whether the drum identification information read out from the drum memory coincides with the drum identification information stored in the main body memory, and enables to execute resister pitch measuring processing of measuring variations in printing pitch due to the photosensitive drum. In a case where it is determined that the drum identification information read out from drum memory coincides with the drum identification information stored in the main body memory, the control unit does not execute the resister pitch measuring processing.

An image formation apparatus according to an embodiment may include: a first image formation unit configured to develop a first image on a medium by using a sublimation printing developer; and a second formation unit configured to develop a second image by using a non-sublimation printing developer in an area outside an area of the first image on the medium.

An image forming apparatus includes a developer case and a developer detection sensor. The developer detection sensor is disposed in contact with a contacted portion located near a developer in the developer case, and detects magnetic permeability of the developer. The developer detection sensor includes a substrate and one or more contact portions that are formed in a facing region on a first surface of the substrate that faces the contacted portion, and configured to come in contact with the contacted portion. A first contact portion that is one of the one or more contact portions includes a detection portion that detects magnetism of the developer. The detection portion is formed in a spiral shape extending from its center part outward. A first magnetic member is provided on the first surface, or on both the first surface and a second surface opposite from the first surface, at a position corresponding to the center part.

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.

An image forming apparatus includes a latent image forming portion configured to form a latent image on an image bearing member; a developing device including a container configured to store toner and a developing member configured to supply the toner to the latent image formed on the image bearing member to form a toner image; an environment sensor configured to detect environmental information related to an environment in which the developing device is placed; and a controller configured to control switching between a first mode and a second mode, in which a number of prints per unit time is less than that in the first mode. The controller is configured to perform switching from the first mode to the second mode based on an update value obtained by adding or subtracting over time an index value weighted in accordance with the environmental information detected by the environment sensor.

According to one embodiment, an image forming apparatus includes an image carrier, an exposing apparatus, a developing device, a transfer device, a fixing device, a history acquisition unit, an estimation unit, and an output unit. The exposing device exposes the image carrier to form an electrostatic latent image on the image carrier. The developing device includes a layer forming member to form a toner layer on a developing roller and forms a toner image by developing the electrostatic latent image. The transfer device transfers the toner image to a sheet. The fixing device fixes the toner image to the sheet. The history acquisition unit acquires a history regarding a temperature around the developing device. The estimation unit estimates a possibility that an image defect caused by the layer formation may occur on the basis of the history. The output unit outputs estimation results of the estimation.

A powder transport device includes: a rotation shaft rotatably supported in a container chamber that contains powder and plural blade members detachably attached to the rotation shaft, the blade members including spiral blades configured to transport the powder in an axial direction of the rotation shaft in response to the rotation shaft rotating.