Abstract: An image forming apparatus includes a main body; a process unit configured to be attached to and removed from the main body, the process unit being configured to integrally hold a plurality of image carriers arranged in a first direction; a plurality of developing cartridges provided in corresponding association with the image carriers, the developing cartridges configured to be attached to and removed from the process unit, each of the developing cartridges including a corresponding developer carrier, each of the developing cartridges being configured to supply developer to a corresponding image carrier; and a pressing mechanism provided in the main body, the pressing mechanism configured to press the developing cartridges, when attached to the process unit, in a direction that the developer carriers contact the image carriers.

Abstract: A thermal fixing device includes: a fixing member configured to be in contact with a fixation medium; a first pressing member disposed to face the fixing member and presses the fixation medium to the fixing member; a second pressing member disposed to face the fixing member at a position downstream in a conveyance direction of the fixation medium with respect to the first pressing member and presses the fixation medium to the fixing member; and a changeover unit configured to change over a pressing force per unit area of at least one of the first pressing member and the second pressing member.

Abstract: At a conveyance direction downstream side of a contact portion between a heat roller and a downstream side pressure roller and at a conveyance direction upstream side of a contact portion (conveyance position) between a conveyance roller and an upstream side pinch roller in a conveyance mechanism part, the conveyance roller is disposed to come in contact with a surface of a sheet opposite to a surface having come in contact with the heat roller. Besides, a first guide member for guiding the sheet to the conveyance position of the conveyance mechanism part is disposed to face the conveyance roller.

Abstract: An image forming apparatus including: a first driven roller that forms a first nip portion with a driving roller; a second driven roller that forms a second nip portion with the driving roller at a downstream side of the first nip portion; a first transfer passage into which the sheet passed through the first nip portion and sent from the second nip portion is transferred by a forward rotation of the driving roller: a second transfer passage into which the sheet passed through the first nip portion is transferred by the forward rotation of the driving roller without passing through the second nip portion; and a third transfer passage into which the sheet is transferred by a reverse rotation of the driving roller after a rear end of the sheet has passed through the first nip portion by the forward rotation of the driving roller.

Abstract: Image forming apparatuses include: a casing; an image forming unit removable from the casing in a first direction; and plural developer cartridges. The cartridges may be attached and detached with respect to the image forming unit in a second direction that is inclined toward the first direction. Other image forming apparatuses include: a casing; an exposure device; a plurality of cartridges configured to be attached and detached with respect to the casing in a first direction; and a recording medium transport system for transporting recording media adjacent the photosensitive members in a second direction. The first direction may be inclined with respect to the second direction, and at least a portion of optical paths of the light emitted from the exposure device may extend parallel with the first direction. Aspects of the invention also relate to image forming units, e.g., for use in image forming apparatuses as described above.

Abstract: A heat roller with which a pressure roller is brought into press contact is rotatably supported by a bearing member made of a material which is softened when heated above a thermal fixation temperature, a thermostat in which a bimetal is exposed toward the heat roller is disposed at the opposite side of the heat roller with respect to the pressure roller, and a heat conduction member is made to intervene between the heat roller and the bimetal. According to the above configuration, the power supply to a fixation heater can be cut off by the thermal deformation of the bimetal. The heat roller is moved by softening of the bearing member, and the bimetal is mechanically deformed by pressing of the heat conduction member. Therefore, the power supply to the fixation heater can be cut off.

Abstract: There are provided a thermal fixing device in which a large expensive mechanism is not needed, and a peeling member can be separated from a fixing member by a simple structure to the extent possible during a fixing operation except when the need arises, and an image forming apparatus including the thermal fixing device. A contact portion coming in contact with a sheet peeled off from a heat roller and for separating a tip portion from a surface of the heat roller is integrally provided to a peeling pawl for peeling the sheet having passed through between the heat roller and respective pressure rollers.

Abstract: An opening and closing mechanism that attaches a cover body to a main body in a manner that the cover body is pivotably opened and closed, includes: a pin provided in one of the main body and the cover body; a link member pivotably provided in the other of the main body and the cover body, the link member having a first guide groove in which the pin is inserted and the pin slides during closing and opening of the cover body with respect to the main body; and a close motion braking member that is a separate member from the pin and the link member and is connected to the link member. The close motion braking member applies an external force to the link member to brake sliding of the pin in the first guide groove during closing of the cover body.

Abstract: An image forming apparatus includes: a cylindrical member made of a metal material; a gear attached to an end portion of the cylindrical member; and an engagement piece made by forming a notch on the cylindrical member and is bent to have a crease extending in a direction crossing a circumferential direction of the cylindrical member, the engagement piece engaging with the gear to prevent the gear from dripping out from the cylindrical member.

Abstract: When fixing images onto normal sheets of paper, the pressing force between a pressing roller and a thermal roller of a fixing unit is designated by the urging force of only a first spring. On the other hand, when fixing images onto thick sheets, the pressing force is designated by the urging force of the first spring and the urging force of a second spring, which operates against the urging force of the first spring.

Abstract: A thermistor is disposed confronting a surface of a heat roller on a downstream side in a rotational direction of a heat roller from a contact position between the heat roller and a pressure roller. Side guide members are provided on both sides of the thermistor and spaced away from the thermistor in the axial direction of the heat roller, and a regulating guide member is disposed connecting the side guide members on the downstream side in the rotational direction of the heat roller. In addition, a separation plate for separating a sheet of paper is provided at a predetermined space from the surface of the heat roller between the contact position and the thermistor in the rotational direction.

Abstract: A thermal fixing device includes: a fixing member configured to be in contact with a fixation medium; a first pressing member disposed to face the fixing member and presses the fixation medium to the fixing member; and a second pressing member disposed to face the fixing member at a position downstream in a conveyance direction of the fixation medium with respect to the first pressing member and presses the fixation medium to the fixing member, wherein the fixing member and the first pressing member apply to a developer on the fixation medium to be pressed by the first pressing member a temperature not lower than a glass transition point of the developer.

Abstract: A thermal fixing device includes: a fixing member configured to be in contact with a fixation medium; a first pressing member disposed to face the fixing member and presses the fixation medium to the fixing member; a second pressing member disposed to face the fixing member at a position downstream in a conveyance direction of the fixation medium with respect to the first pressing member and presses the fixation medium to the fixing member; and a changeover unit configured to change over a pressing force per unit area of at least one of the first pressing member and the second pressing member.

Abstract: At a conveyance direction downstream side of a contact portion between a heat roller and a downstream side pressure roller and at a conveyance direction upstream side of a contact portion (conveyance position) between a conveyance roller and an upstream side pinch roller in a conveyance mechanism part, the conveyance roller is disposed to come in contact with a surface of a sheet opposite to a surface having come in contact with the heat roller. Besides, a first guide member for guiding the sheet to the conveyance position of the conveyance mechanism part is disposed to face the conveyance roller.

Abstract: There are provided a thermal fixing device in which a large expensive mechanism is not needed, and a peeling member can be separated from a fixing member by a simple structure to the extent possible during a fixing operation except when the need arises, and an image forming apparatus including the thermal fixing device. A contact portion coming in contact with a sheet peeled off from a heat roller and for separating a tip portion from a surface of the heat roller is integrally provided to a peeling pawl for peeling the sheet having passed through between the heat roller and respective pressure rollers.

Abstract: A heat roller with which a pressure roller is brought into press contact is rotatably supported by a bearing member made of a material which is softened when heated above a thermal fixation temperature, a thermostat in which a bimetal is exposed toward the heat roller is disposed at the opposite side of the heat roller with respect to the pressure roller, and a heat conduction member is made to intervene between the heat roller and the bimetal. According to the above configuration, the power supply to a fixation heater can be cut off by the thermal deformation of the bimetal. The heat roller is moved by softening of the bearing member, and the bimetal is mechanically deformed by pressing of the heat conduction member. Therefore, the power supply to the fixation heater can be cut off.

Abstract: A toner image that is formed on a photosensitive drum is transferred onto a paper and the paper is fed between a heat roller and a pressure roller so that the toner is fixed onto the paper. The guide plate for guiding the paper between the heat roller and the pressure roller is arranged so as to contact the paper between a first surface and a second surface. Because the position of the paper is fed stably, the toner is not scattered from the paper and deterioration in the image is prevented.

Abstract: In a thermal fixing device, a thermister, a temperature fuse and a thermostat are disposed in alignment with symmetrical positions spaced by a predetermined distance from the axial center of a heat roller, that is, a temperature distribution center of a heater. Accordingly, the temperature fuse and the thermostat can sense substantially the same temperature as that sensed by the thermister, and the temperature fuse and the thermostat function as thermal cutoff devices promptly and properly to prevent the heat roller from overheating when the heat roller is excessively heated.

Abstract: When fixing images onto normal sheets of paper, the pressing force between a pressing roller and a thermal roller of a fixing unit is designated by the urging force of only a first spring. On the other hand, when fixing images onto thick sheets, the pressing force is designated by the urging force of the first spring and the urging force of a second spring, which operates against the urging force of the first spring.

Abstract: Toner and paper powder adhering to and carried by the image non-forming surface of a paper sheet in a developing unit are prevented from fixedly transferring and adhering to the inner wall of the developing unit and the inner wall of the paper sheet introduction port of a fixing unit. As a result, the paper sheet is smoothly carried from the developing unit to the fixing unit while reliably preventing a paper sheet jam. To prevent the adherence of toner and paper powder to the inner walls, first ribs are formed on the bottom surface of the top cover of the developing chamber of the processing unit and second ribs are formed on the paper sheet introduction port side of the top cover of the fixing room of the fixing unit. The first ribs and the second ribs are staggered with respect to one another. In addition, a discharging film is disposed between pairs of adjacent first ribs on the bottom surface of the top cover of the developing chamber.