An image forming apparatus includes: an image carrier having a first rotation axle, a charging roller having a second rotation axle, a conductive member to contact a surface of the image carrier, a gap size acquisition device, and a gap adjustment device. The charging roller is disposed adjacent to the image carrier in a non-contact manner across a gap to charge the image carrier. The gap size acquisition device acquires a size of the gap. The gap adjustment device adjusts a distance between the first rotation axle and the second rotation axle based on information from the gap size acquisition device to maintain the size of the gap within a predetermined range.

An image forming apparatus includes a print engine including a photosensitive drum forming an image on an image forming medium, a charging member charging the photosensitive drum, a power supply to provide a charging power supply having a reference charging voltage to the charging member, a sensor to detect an image density of an image formed on the image forming medium, and a processor to control the power supply to change a magnitude of voltage of the charging power supply within a predetermined voltage range at predetermined periods, and to identify an occurrence of a background with respect to the photosensitive drum based on an image density detected by the sensor while the charging power supply is changed.

A roller charging device may include a Y-shaped electrically conductive brush and a screw terminal coupling the Y-shaped electrically conductive brush to a housing of the roller charging device and electrically coupling the Y-shaped electrically conductive brush to a power source. A printing fluid developer may include a plurality of rollers and a plurality of Y-shaped brushes to each contact one of the plurality of rollers wherein each of the Y-shaped brushes provides an electrical charge to each of the plurality of rollers.

An assembly for an electrophotographic image forming device according to one example includes a rotatable roll having an electrically conductive shaft. An electrically conductive bracket is positioned adjacent to the roll and in a spaced relationship from the roll along a length of the roll. An electrical contact is positioned to receive an electrical voltage from a power supply of the image forming device. The electrical contact is electrically connected to a first end portion of the shaft of the roll by way of a first electrical path and to a second end portion of the shaft of the roll by way of a second electrical path to transfer the electrical voltage to the roll. The bracket forms a portion of the second electrical path such that the electrical voltage transferring from the electrical contact to the second end portion of the shaft of the roll passes through the bracket.

A charging device includes a first charging unit that charges a target unit, which is to be charged, by coming into contact with the target unit and a second charging unit that charges the target unit by coming into contact with the target unit and in which distribution of a contact region in contact with the target unit is different from distribution of a contact region in the first charging unit.

An assembly for an electrophotographic image forming device according to one example includes a rotatable roll having an electrically conductive shaft. An electrically conductive bracket is positioned adjacent to the roll and in a spaced relationship from the roll along a length of the roll. An electrical contact is positioned to receive an electrical voltage from a power supply of the image forming device. The electrical contact is electrically connected to a first end portion of the shaft of the roll by way of a first electrical path and to a second end portion of the shaft of the roll by way of a second electrical path to transfer the electrical voltage to the roll. The bracket forms a portion of the second electrical path such that the electrical voltage transferring from the electrical contact to the second end portion of the shaft of the roll passes through the bracket.

In an image forming apparatus, a bias controller varies one, while keeping the other fixed, of a charging alternating-current frequency, which is the frequency of the charging alternating-current voltage, and a developing alternating-current frequency, which is the frequency of the developing alternating-current voltage. Specifically, in a case where interference fringes appear in a developed image due to interference between the charging and developing alternating-current frequencies, when the recognizable minimum pitch of the interference fringes is A.sub.1 (mm), the width of the variation region of the other frequency is B.sub.1 (Hz), the rotation speed of an image carrying member is C.sub.1 (mm/sec), and the variation speed of the other frequency in the variation region is D.sub.1 (Hz/sec), the bias controller varies the other frequency at a variation speed D.sub.1 that fulfills |D.sub.1|>B.sub.1/(A.sub.1/C.sub.1).

A power supply device includes a rectification circuit that is supplied with AC power from an AC power supply, a power factor improvement circuit that boosts an output voltage of the rectification circuit, smooths a boosted voltage with a capacitor, and thereby generates a DC output voltage outputted to a load circuit, a DC-DC converter that steps down the DC output voltage to a prescribed first voltage, a DC output voltage detection circuit that detects whether or not the DC output voltage satisfies a prescribed condition, and a switch circuit that temporarily puts the power factor improvement circuit in an operating state by use of the first voltage each time the prescribed condition is satisfied in a period in which the power factor improvement circuit is in a stopped state due to an energy saving mode of the load circuit.

A roller charging device may include a Y-shaped electrically conductive brush and a screw terminal coupling the Y-shaped electrically conductive brush to a housing of the roller charging device and electrically coupling the Y-shaped electrically conductive brush to a power source. A printing fluid developer may include a plurality of rollers and a plurality of Y-shaped brushes to each contact one of the plurality of rollers wherein each of the Y-shaped brushes provides an electrical charge to each of the plurality of rollers.

A conductive structure of a process cartridge that includes a cartridge body and a charging roller, includes: a first support member and a second support member arranged at opposite ends of the charging roller along an axial direction of the charging roller; a metal conductive member connected to the first support member, the conductive member including a first end penetrating the first support member and directly contacting the charging roller, and a second end located outside the first support member; a conductive spring connected to the second end of the conductive member, the conductive spring including a first end connected to the first support member, and a second end abutting against the cartridge body; and a conductive wire having one end connected to the conductive spring, wherein the conductive wire, the conductive spring, and the conductive member constitute a conductor for stable current delivery.