Abstract: A developing unit includes a plurality of developing rolls over which a developer is conveyed and supplied onto an image carrier which is rotatably supported; and at least one pair of the developing rolls being adjacent to each other. In the pair of the developing rolls, one developing roll rotates in a direction opposite to a rotary direction of the image carrier, and the other developing roll rotates in the same direction of the rotary direction of the image carrier. A regulation member is interposed between the pair of the developing rolls. The regulation member regulates a conveyed amount of the developer. The regulation member is disposed to be opposed to a magnet which is provided within the two adjacent developing rolls. A polarity of the magnet in the pair of developing rolls opposed to each other is different from each other.

Abstract: A disclosed developing device includes a developer carrier including a developing sleeve and a magnetic roller provided inside the developing sleeve. The magnet roller includes a regulating magnetic pole and a pump-up magnetic pole that have different polarities from each other. Among an entire region of the moving surface of the developing sleeve in the surface movement direction, a maximum pump-up magnetic force position where the pump-up magnetic force of the pump-up magnetic pole is maximum faces an upstream position with respect to a supplying position at which the developer is supplied from a supplying screw to the developing sleeve.

Abstract: A developing device is disclosed. The developing device includes a developing roller disposed to face an image carrier and a toner carrier capturing roller disposed to face the developing roller for capturing toner carriers adhered onto the image carrier. The developing roller generates a magnetic pole at a side facing the toner carrier capturing roller. A first virtual line, which connects a rotational center of the developing roller to a rotational center of the toner carrier capturing roller, passes through a region between a position where a magnetic flux density of the magnetic pole in the normal line direction is minimum on the developing roller at the upstream side in the rotational direction of the developing roller and a position where the magnetic flux density of the magnetic pole in the normal line direction is maximum on the developing roller.

Abstract: In a charging device having saw-tooth electrodes for generating corona discharges, an amount of dust, toner, or paper dust attached to the tip end portions of saw-tooth electrodes is reduced. First to third pairs of saw-tooth electrode plates are disposed in a side-by-side fashion along the periphery of a photosensitive drum in which the first pair is disposed at an upstream side with respect to a direction in which the photosensitive drum rotates, the third pair at a downstream side, and the second pair at a central portion between the remaining two. A current flowing per a unit length of the second pair is set to 1.3 to 3 times as much as a current flowing per a unit length of each of the first and third pairs. The currents flowing per a unit length of the first and third pairs are set to be equal to each other.

Abstract: A disclosed developing device is for accommodating a developer including carriers and a toner, and for developing a latent image formed on an image carrier. The developing device includes plural developer conveying units configured to convey the developer accommodated in the developing device and form circulating paths; and a ventilation unit configured to perform ventilation between at least one of the developer conveying units whose internal pressure increases and at least one of the developer conveying units whose internal pressure decreases.

Abstract: A developing unit containing developer including carrier and toner and developing a latent image formed on an image carrier is disclosed. The developing unit includes multiple conveyor members configured to convey the contained developer in respective longitudinal directions so as to form a circulation channel; a supply part configured to supplement the carrier in the developing unit; a discharge part configured to discharge a first part of the contained developer outside the developing unit; and a bypass channel configured to cause a second part of the developer to return to the upstream side of the circulation channel without passing a position where the discharge part is provided.

Abstract: A development apparatus includes a first developer chamber configured to store and supply the developer, a first developer bearer configured to convey the developer supplied from the first developer chamber to a first development domain, defined by a portion of the first developer bearer facing a latent image bearer, to develop the latent image, a second developer bearer configured to convey the developer passed through the first development domain to a second development domain, defined by a portion of the second developer bearer facing the latent image bearer, to develop the latent image, a second developer chamber configured to recover the developer passing through the second development domain and store the recovered developer, and a transfer prevention member provided between the second developer chamber and the second developer bearer to reduce a transfer of the developer from the second developer chamber to the second developer bearer.

Abstract: An image forming apparatus includes a latent image carrier and a developing device configured to develop a latent image carried by the latent image carrier. In the developing device, a receive-convey screw conveys a developer received from a developer carrier. The receive-convey screw includes a receive-convey blade including a lower, outer circumferential end located in a downstream end of the receive-convey blade in the developer conveyance direction of the receive-convey screw. A slant-convey screw is disposed obliquely relative to an axial direction of the receive-convey screw, and conveys the developer received from the receive-convey screw upward. The slant-convey screw includes a slant-convey blade including a lower, outer circumferential end located in an upstream end of the slant-convey blade in the developer conveyance direction of the slant-convey screw, the lower, outer circumferential end being located at a height level lower than the lower, outer circumferential end of the receive-convey blade.

Abstract: A developing unit includes a plurality of developing rolls over which a developer is conveyed and supplied onto an image carrier which is rotatably supported; and at least one pair of the developing rolls being adjacent to each other. In the pair of the developing rolls, one developing roll rotates in a direction opposite to a rotary direction of the image carrier, and the other developing roll rotates in the same direction of the rotary direction of the image carrier. A regulation member is interposed between the pair of the developing rolls. The regulation member regulates a conveyed amount of the developer. The regulation member is disposed to be opposed to a magnet which is provided within the two adjacent developing rolls. A polarity of the magnet in the pair of developing rolls opposed to each other is different from each other.

Abstract: In a charging device having saw-tooth electrodes for generating corona discharges, an amount of dust, toner, or paper dust attached to the tip end portions of saw-tooth electrodes is reduced. First to third pairs of saw-tooth electrode plates are disposed in a side-by-side fashion along the periphery of a photosensitive drum in which the first pair is disposed at an upstream side with respect to a direction in which the photosensitive drum rotates, the third pair at a downstream side, and the second pair at a central portion between the remaining two. A current flowing per a unit length of the second pair is set to 1.3 to 3 times as much as a current flowing per a unit length of each of the first and third pairs. The currents flowing per a unit length of the first and third pairs are set to be equal to each other.

Abstract: In a scorotron type charging device including a shield case having an opening portion toward a photosensitive body, sawtooth electrodes for generating a corona discharge, and a grid having plural grid wires provided at a predetermined interval from sawtooth electrodes, at least one side surface of shield case is arranged adjacent to one sawtooth electrode, and a relationship between a current It supplied to sawtooth electrodes and current Is flowing through shield case is set to satisfy a conditional expression of ¼?Is/It?½, and an interval between vertexes of sawteeth of the sawtooth electrodes is set to 1 mm or more but 3 mm or less and a relationship between a charged potential Vo of the photosensitive body and a voltage Vg applied to grid is set to satisfy a conditional expression of ?50 V?|Vo|?|Vg|?50 (V).

Abstract: An ultraviolet curable resin composition includes (A) an ultraviolet curable resin, (B) an epoxy compound having at least two epoxy groups in one molecule, (C) a photopolymerization initiator and (D) a diluent. The ultraviolet curable resin (A) is obtained by the steps of polymerizing an ethylenically unsaturated monomer component containing (a) an ethylenically unsaturated monomer having epoxy group and (b) a compound having at least two ethylenically unsaturated groups in one molecule to prepare a copolymer, reacting the copolymer with (c) an ethylenically unsaturated monomer having carboxyl group to prepare a chemical intermediate, and reacting the chemical intermediate with (d) one of saturated and unsaturated polybasic acid anhydrides. This resin composition will be preferably used to prepare a photo solder resist ink developable with diluted alkaline aqueous solution.