A system and method for producing a uniform layer of toner on a developer roller of a toner-based printer includes two or more doctor blades that are configured to reduce the amount of toner deposited on the developer roller in successive steps. A first doctor blade reduces the layer of toner to a first depth, and a second doctor blade further reduces the layer of toner to a second depth. A third or subsequent doctor blade can further reduce the layer of toner to a third depth. An electrical charge applied to one or more of the doctor blades produces a substantially uniform charge to the layer of toner on the developer roller.

A developing device includes: an image bearing member; a plurality of developing rollers each supplying toner to the image bearing member, and developing an electrostatic latent image on the image bearing member into a toner image; and a hardware processor analyzing values representing density fluctuations during the toner being supplied from the developing rollers to the image bearing member, for the respective developing rollers, and correcting a control value for an image density of at least one developing roller among the developing rollers based on an result of the analyzing so as to eliminate the density fluctuations, in consideration of an effect caused at the developing roller on a downstream side in a rotational direction of the image bearing member by correcting the control value for the image density of the developing roller on an upstream side.

A developing device includes a first chamber, a first feeding screw, a second chamber, a second feeding screw, a first rotatable member, a first magnet, a second rotatable member, a second magnet, a third rotatable member, a third magnet, and a guiding portion. In a case that a shortest distance between the second rotatable member and the guiding portion is B [?m], and a shortest distance between the third rotatable member and the guiding portion is C [?m], the following relationship is satisfied: B+100 ?m?C.

A developing device includes a developing roller which includes: a magnet roller having a plurality of magnetic poles in a circumferential direction; and a developing sleeve rotatably supported along an outer peripheral surface of the magnet roller, and which is configured to supply a toner to an image bearing member. The magnet roller is configured so that the relative position thereof to the developing sleeve is changeable.

An image forming apparatus includes: a photoconductor drum; a developing device having a plurality of developer rollers and supplying toner to the photoconductor drum; a first pressing force applier that applies a force to the developing device to press the plurality of developer rollers toward the photoconductor drum; and a second pressing force applier that flexibly holds the developing device in a vertical direction.

A developing device includes a first developing roller, a second developing roller, a first end portion configured to restrict the amount of developer on the second developing roller, a restriction member, and a collecting roller configured to collect developer on the first developing roller. The second end portion is located at a position where magnetic force interference with a magnetic force generated by the second developing roller and the collecting roller is not caused.

A developing device includes a developing roller which includes: a magnet roller having a plurality of magnetic poles in a circumferential direction; and a developing sleeve rotatably supported along an outer peripheral surface of the magnet roller, and which is configured to supply a toner to an image bearing member. The magnet roller is configured so that the relative position thereof to the developing sleeve is changeable.

A developing device includes a developer bearer rotatable in a rotation direction and forming a developing range, a holder, and an entrance seal. The holder has a facing face facing the developer bearer upstream from the developing range in the rotation direction, a support face defining a part of an outer face of the developing device, and a relay face extending from one end of the support face to one end of the relay face connected to the facing face to form an acute tip portion closer to the developing range than the one end. The entrance seal has a free end projecting from the one end as a cantilever, and a length of the entrance seal from a tip of the free end of the entrance seal to the one end is shorter than a length of the relay face from the acute tip portion to the one end.

A developing device includes a developer bearer, a developer regulator, a casing including an opposing face to oppose the developer bearer upstream from a developing range in a direction of rotation of the developer bearer, and first, second, and third seals. The first seal includes a first end secured to the casing and a second end to contact a latent image bearer upstream from the developing range in a direction of rotation of the latent image bearer. The second seal includes a first end secured to the opposing face of the casing, and a second end to contact the first seal upstream from the developing range. The third seal includes a first end secured to the opposing face of the casing, and a second end to contact developer on the developer bearer between the developer regulator and the developing range in the direction of rotation of the developer bearer.

A first maximum position where a magnetic flux density of a first magnetic pole is maximum is positioned downstream of a first developing position and upstream of a first closest position. A second maximum position where a magnetic flux density of a third magnetic pole is maximum is positioned downstream of a second closest position and upstream of a second developing position. A relationship of r11>r22 is satisfied, in a case where r1 represents a radius of a first rotatable developing member, r2 represents a radius of a second rotatable developing member, 1 represents an angle from the first maximum position to the first closest position in the rotational direction of the first rotatable developing member, and 2 represents an angle from the second closest position to the second maximum position in the rotational direction of the second rotatable developing member.