Abstract: Developing bias is set as follows. An electric field intensity between a developing roller and a photoconductor is set to cause normally-charged toner to fly in an image area and not to cause the toner to fly in a background area. Thus, the normally-charged toner does not fly in the background area. The normally-charged toner caused to fly is therefore unlikely to flick low-charged toner and oppositely-charged toner. The low-charged toner and the oppositely-charged toner will not adhere to the background area and cause image fogging. Accordingly, an image forming apparatus can be provided to prevent the low-charged toner and the oppositely-charged toner from adhering to the background area of an electrostatic latent image on the photoconductor and to avoid the occurrence of image fogging in the background area on a printed material.

Abstract: A fixing device thermally fixes an unfixed image on a recording sheet by passing the recording sheet through a fixing nip. The fixing device has: a heat-generating endless belt; a first pressure member inside a running path of the endless belt; a second pressure member pressing the endless belt against the first pressure member from outside the running path to form the fixing nip, and a pair of power feeders. The endless belt includes: a circumferential resistive heat layer that generates heat upon receiving electric current; and a first electrode and a second electrode flanking a sheet passing area of the circumferential surface of the endless belt. Each electrode is composed of a pair of electrode layers, one on the inner and another on the outer circumferential surface of the resistive heat layer. Each power feeder is in contact with both the electrode layers of a different electrode.

Abstract: An electrostatic chuck is provided with a ceramic substrate 12 in which an electrode 14 is embedded, an electrode terminal 14a exposed at the bottom of a concave portion 16 disposed on the back surface of the ceramic substrate 12, a power feed member 20 to supply an electric power to the electrode 14, and a joining layer 22 to connect this power feed member 20 to the ceramic substrate 12. The joining layer 22 is formed by using a AuGe based alloy, a AuSn based alloy, or a AuSi based alloy. The ceramic substrate 12 and the power feed member 20 are selected in such a way that the thermal expansion coefficient difference D calculated by subtracting the thermal expansion coefficient of the ceramic substrate 12 from the thermal expansion coefficient of the power feed member 20 satisfies ?2.2?D?6 (unit: ppm/K).

Abstract: A fixing device for fixing an unfixed image formed on a sheet by passing the sheet through a fixing nip, the fixing device comprising: a pair of ring-shaped electrodes each disposed along a different one of edges of endless belt and flanking a sheet-passing region on an external circumferential surface of the belt; and a pair of power feeders each being in contact with a different one of the ring-shaped electrodes at a contact area and feeding power to a resistive heat layer included in the belt, at least one of the power feeders being located at a position upstream from the fixing nip in a rotation direction of the belt and allowing a portion of the belt between the fixing nip and the contact area to be in close contact with the first roller while the belt is being rotated.

Abstract: A method for manufacturing an alumina sintered body of the present invention comprises: (a) forming a mixed powder containing at least Al2O3 and MgF2 or a mixed powder containing Al2O3, MgF2, and MgO into a compact having a predetermined shape; and (b) performing hot-press sintering of the compact in a vacuum atmosphere or a non-oxidizing atmosphere to form an alumina sintered body, in which when a amount of MgF2 to 100 parts by weight of Al2O3 is represented by X (parts by weight), and a hot-press sintering temperature is represented by Y (° C.), the hot-press sintering temperature is set to satisfy the following equations (1) to (4) 1,120?Y?1,300??(1) 0.15?X?1.89??(2) Y??78.7X+1,349??(3) Y??200X+1,212??(4).

Abstract: A fixing device includes: a pressure belt movable in a revolving motion; a fixing roller; and a pressure member for pressing an inner surface of the belt toward the roller. A fixing nip is formed between the roller and the belt while an elastically deformable surface of the roller is contacted with the belt by pressure applied by the pressure member to the belt. The pressure member includes: an elastic member for applying pressures so that greater pressure is applied to center of the roller than to the ends, the center and the ends being along axis direction of the roller; and a hard member that is disposed parallel to the elastic member on downstream side thereof in a revolving direction of the belt and applies pressures to the roller so that greater pressure is applied to the ends than to the center.

Abstract: The present invention provides a developing device which is capable of suppressing the generation of a fogging phenomenon and deposition of carrier particles to an electrostatic latent image carrier and developing the electrostatic latent image efficiently, the device includes a development sleeve and a magnet body onto which the sleeve is fitted, and using a two-component developer. An angular position which indicates the peak value of the magnetic flux density in the normal direction produced by a development pole of the magnet body is shifted downstream from the center position of the development pole in the direction of movement of the surface of a photosensitive member in a development region. The present invention also provides an image forming apparatus which can form high-quality images with reduced noise such as fogging by mounting the developing device.

Abstract: A fixing device for thermally fixing an unfixed image formed on a recording sheet by passing the recording sheet through a fixing nip. The fixing device has: a heat-generating endless belt having, on a circumferential surface thereof, a sheet passing area through which the recording sheet passes; a first pressure member disposed inside a running path of the endless belt; and a second pressure member disposed to press the endless belt against the first pressure member from outside the running path to form the fixing nip. The endless belt includes: a resistive heat layer that generates heat upon receiving electric current; and a pair of electrode layers that receive electric current. The electrode layers flank the sheet passing area. The resistive heat layer is in contact with the electrode layers at a different one of end faces opposing each other in a width direction of the resistive heat layer.

Abstract: A fixing device thermally fixes an unfixed image on a recording sheet by passing the recording sheet through a fixing nip. The fixing device has: a heat-generating endless belt; a first pressure member inside a running path of the endless belt; a second pressure member pressing the endless belt against the first pressure member from outside the running path to form the fixing nip, and a pair of power feeders. The endless belt includes: a circumferential resistive heat layer that generates heat upon receiving electric current; and a first electrode and a second electrode flanking a sheet passing area of the circumferential surface of the endless belt. Each electrode is composed of a pair of electrode layers, one on the inner and another on the outer circumferential surface of the resistive heat layer. Each power feeder is in contact with both the electrode layers of a different electrode.

Abstract: A fixing device for thermally fixing an unfixed image formed on a recording sheet by passing the recording sheet through a fixing nip. The fixing device has a heat-generating endless belt that includes: a resistive heat layer that generates heat upon receiving electric current; and a pair of electrode layers each disposed along a different one of widthwise edges of the heat-generating endless belt. The resistive heat layer has (i) reduced thickness portions each along a widthwise edge thereof and (ii) a middle portion between the reduced thickness portions. Each reduced thickness portion is thinner than the middle portion and connected to the middle portion with a wall surface upright in a direction perpendicular to the rotation axis of the heat-generating endless belt to define a stair shape. Each electrode layer is disposed on the resistive heat layer to be in contact with a corresponding one of the wall surfaces.

Abstract: Disclosed is a fixing device for thermally fixing an unfixed image onto the recording sheet, the fixing device comprising: a fixing belt; and a meander regulation member provided adjacent to an edge of the fixing belt in a width direction thereof, and operable to prevent meandering of the fixing belt, wherein the fixing belt includes: a resistive heat layer that is tubular and generates heat when an electric current is applied thereto; and first and second electrodes that are provided circumferentially on an outer circumferential surface of the resistive heat layer, and that receive and apply the electric current to the resistive heat layer, and the first electrode is provided closer to the meander regulation member than to the second electrode, and is at a distance from the edge of the fixing belt in the width direction thereof.

Abstract: A fixing device for thermally fixing an unfixed image onto a recording sheet by causing the sheet to pass through a fixing nip. The fixing device includes: heat belt formed in an endless shape and provided with a resistance heat layer; first pressure member provided inside a running path of the heat belt; and second pressure member pressing the first pressure member from over the running path to form the fixing nip. At least one of the first and second pressure members is rotating body. The heat belt has a pressure-receiving area and two non-pressure areas. The pressure-receiving area receives pressures from both the first and second pressure members. The non-pressure areas have been arranged at outside of the pressure-receiving area in an axis direction of the rotating body. Two ring-like electrodes have been formed on circumferential surfaces of the non-pressure areas and are used to supply power to the resistance heat layer.

Abstract: A fixing device has a presser member, a slide member and a pressure belt. Both ends of the presser member are positioned outside both ends of the slide member. Both ends of the slide member are positioned outside both ends of the pressure belt. Thereby, the slide member and the pressure belt are improved in service life, so that the fixing device as a whole is improved in service life.

Abstract: A method for producing an aluminum nitride sintered product according to the present invention includes the steps of (a) preparing a powder mixture that contains AlN, 2 to 10 parts by weight of Eu2O3 with respect to 100 parts by weight of AlN, Al2O3 such that a molar ratio of Al2O3 to Eu2O3 is 2 to 10, and TiO2 such that a molar ratio of TiO2 to Al2O3 is 0.05 to 1.2, but not Sm; (b) producing a compact from the powder mixture; and (c) firing the compact by subjecting the compact to hot-press firing in a vacuum or in an inert atmosphere.

Abstract: A fixing device includes: a heating rotary member having a heating layer generating heat upon current application; a pressurizing rotary member brought into pressure-contact with an outer circumferential surface of the heating rotary member to form fixing nip, through which a sheet on which unfixed toner image is formed passes for heat fixing; circular electrodes that are circumferentially formed at two respective positions sandwiching a sheet passing region therebetween, on the outer circumferential surface, and feed electrical power to the heating layer, the electrodes are each metallic and formed of at least two electrode layers including a first electrode layer layered directly on the heating layer and a second electrode layer as an outermost layer, linear expansion coefficient difference between the first layer and the heating layer is smaller than that between the second layer and the heating layer, and the second layer is more oxidation-resistant than the first layer.

Abstract: A fixing device for fixing a toner image onto a recording sheet, the fixing device comprising: a fixing belt including, on an inner circumference side thereof, a resistance heating layer, extending over entire circumference of the fixing belt, operable to emit heat upon flowing of an electric current therethrough; a pressing member operable to press an outer circumference of the fixing belt to form a fixing nip therebetween so that, while the recording sheet passes through the fixing nip, the toner image is fixed onto the recording sheet; and a pair of power supply members arranged inside the fixing belt along the circumferential direction with a predetermined distance therebetween, the power supply members being in contact with the inner circumferential surface of the resistance heating layer in an electrically conductive state along a direction perpendicular to the circumferential direction.

Abstract: The development apparatus that develops an electrostatic latent image formed on an image carrier comprises: a developer roller operable to carry toner on a circumferential surface thereof and develop the electrostatic latent image using the toner; a supply roller operable to perform toner supply to the developer roller; a voltage applier operable to apply a bias voltage V1 to the developer roller and apply a bias voltage V2 to the supply roller; and a controller operable to control the voltage applier in a toner compulsive consumption mode so that a value obtained by subtracting an average S2 of the bias voltage V2 per unit time from an average S1 of the bias voltage V1 per unit time indicates the same polarity as a normal charging polarity of the toner. Here, the toner compulsive consumption mode performs development to compulsively consume the toner carried on the circumferential surface of the developer roller.

Abstract: A potential difference between the photoreceptor and the development roller is set at a value at which the normally charged toner on the development roller can be flown toward the photoreceptor in the development phase at the time of compulsorily consuming the toner, and this potential difference is set at a value at which the flown normally charged toner can be returned to the development roller in the recovery phase.

Abstract: Fixing device for fixing image onto recording sheet by applying heat and pressure thereto while it passes through fixing nip, including: pressure belt movable in revolving motion; fixing roller; and pressure member for pressing inner surface of the belt toward the roller. The fixing nip is formed between the roller and belt while elastically deformable surface of the roller is contacted with the belt by pressure applied by pressure member to the belt. The pressure member includes: elastic member for applying pressures so that greater pressure is applied to center of the roller than to ends, the center and ends being along axis direction of the roller; and hard member that is disposed parallel to the elastic member on downstream side thereof in revolving direction of the belt and applies pressures to the roller so that greater pressure is applied to end0s than to center.

Abstract: A method for manufacturing an alumina sintered body of the present invention comprises: (a) forming a mixed powder containing at least Al2O3 and MgF2 or a mixed powder containing Al2O3, MgF2, and MgO into a compact having a predetermined shape; and (b) performing hot-press sintering of the compact in a vacuum atmosphere or a non-oxidizing atmosphere to form an alumina sintered body, in which when a amount of MgF2 to 100 parts by weight of Al2O3 is represented by X (parts by weight), and a hot-press sintering temperature is represented by Y (° C.), the hot-press sintering temperature is set to satisfy the following equations (1) to (4) 1,120?Y?1,300??(1) 0.15?X?1.89??(2) Y??78.7X+1,349??(3) Y??200X+1,212??(4).