Abstract: An image forming apparatus which includes a fixing device including a fixing roller, a pressure roller pressed into contact with the fixing roller, and a thermistor in contact with a non-paper-passage region on the surface of the fixing roller, the fixing roller incorporating a first halogen heater whose heat distribution based on the axial direction of the fixing roller is set such that heat in a middle region thereof is higher than heat in opposite-end regions thereof, and a second halogen heater whose heat distribution based on the axial direction of the fixing roller is set such that heat in opposite-end regions thereof is higher than heat in a middle region thereof; and a controller for controlling power supply to the first and second halogen heaters. The controller starts power supply to the first and second halogen heaters to start warm-up of the fixing device, and cuts off power supply to the first halogen heater for a predetermined period of time during the warm-up.

Abstract: An image forming apparatus comprising: a fixing device including a fixing roller, a pressure roller pressed into contact with the fixing roller, and a thermistor in contact with a non-paper-passage region on the surface of the fixing roller, the fixing roller incorporating a first halogen heater whose heat distribution based on the axial direction of the fixing roller is set such that heat in a middle region thereof is higher than heat in opposite-end regions thereof, and a second halogen heater whose heat distribution based on the axial direction of the fixing roller is set such that heat in opposite-end regions thereof is higher than heat in a middle region thereof; and a controller for controlling power supply to the first and second halogen heaters. The controller starts power supply to the first and second halogen heaters to start warm-up of the fixing device, and cuts off power supply to the first halogen heater for a predetermined period of time during the warm-up.

Abstract: This invention relates to an image forming apparatus for recording an image on recording paper. The apparatus has a main base frame internally provided with an imaging unit for recording an image on recording paper, an upper frame disposed on-the main base frame and pivotally movable about an axis of a pivot provided on one end of the upper frame corresponding to a rear side of the apparatus to open a front side of the apparatus, a document feeder unit disposed on the upper frame for feeding an original document set thereon toward the front side, a document discharge tray attached to the main base frame for receiving the document fed by the document feeder unit, and a recording paper discharge tray attached to the main base frame beneath the document discharge tray for receiving the recording paper carrying the recorded image. The document discharge tray and the recording paper discharge tray are integrally attached to the main base frame via a tray frame to form a one piece unit.

Abstract: An image forming apparatus of this invention is constructed such that a main base frame constituting the apparatus is formed with a pair of first positioning pins. An attachment member is formed with a pair of second positioning pins and positioning holes for fittingly receiving the first positioning pins therein to position the attachment member relative to the main base frame. A brake force supplier formed with mounting holes is attached to the attachment member while positioned relative thereto by fitting insertion of the second positioning pins in the mounting holes. When the attachment member is not used, another brake force supplier can be directly mounted on the main base frame and positioned relative thereto by fitting insertion of the first positioning pins in mounting holes of the brake force supplier.

Abstract: This invention relates to an image forming apparatus constructed such that an upper frame is openably mounted on a main base frame and a pivotal movement transmitter (gear) is rotatably mounted on the upper frame about an axis of a rotation of the upper frame, i.e., in association with the rotation of the upper frame. The gear has a cam portion. One end of a lever comes into contact with part of the cam portion of the gear, while the opposite end of the lever comes into contact with a coil spring. Further, a distance from the pivotal axis of the gear to the contact position of the lever with the cam portion decreases in accordance with a proceeding of the closing operation. Accordingly, as the lever (cam follower) follows the cam portion in accordance with the closing operation of the upper frame, a compression force to compress the coil spring increases. Thereby, a brake force applied to the upper frame on the way of closing also increases.

Abstract: A paper feeding device is capable of judging that a paper jam occurs on the basis of output from a first paper detecting switch and a second paper detecting switch. These paper detecting switches are respectively provided ahead of and behind a registration roller which feeds paper sheets to an image forming section. If the first paper detecting switch is turned on when a predetermined time has elapsed since the registration roller started to feed a paper sheet to the image forming section, it is judged that a duplicate paper feeding state has occurred where a plurality of paper sheets are simultaneously fed. If the second paper detecting switch is turned off in the case where it is judged that a duplicate paper feeding state has occurred, it is judged that a paper jam has not occurred. The registration roller is stopped so it will later be ready to feed the subsequent paper sheet.

Abstract: A paper-discharge tray for an image-forming apparatus is adapted to hold paper discharged by a paper-discharging device arranged downstream of a fixing device in the image-forming apparatus. The free end of the paper-discharge tray is adapted to be bent in the direction in which the paper will curl when it passes through the fixing device, such that the paper can be stably stacked even when it curls during the fixing process.

Abstract: A paper feeding cassette case in an image forming apparatus according to the present invention is so adapted that an arbitrary internal unit out of a plurality of types of internal units including at least one internal unit of a universal type having a structure in which paper sheets of a plurality of sizes requiring the switching of the printing ranges can be set can be attached thereto. In the paper feeding cassette case, detecting member mounting portions are respectively formed in different positions respectively corresponding to the types of internal units, and the detecting member and each of the detecting member mounting portions are provided with mounting member for detachably mounting the detecting member on the detecting member mounting portion.

Abstract: An image forming apparatus including a transfer discharger. A sheet material after transfer is detached from a photosensitive drum by virtue of its stiffness and its own weight. The sheet material detached from the drum is guided by a guiding member. The guiding member is made of insulating material and provided with a plurality of ribs. A charge removing member is disposed on a downstream side of the guiding member. Charge removing action occurs over spaces between the ribs and charges on a rear surface of the sheet material are removed as the sheet material is being guided by the ribs. The guiding member may be formed of antistatic material in at least a part of it which comes into contact with the sheet material. Further, the guiding member may include assisting guide portions in at least some of the spaces between the ribs for guiding a receiving substrate such as a sheet material, an envelope, or the like to upper portions of the ribs.

Abstract: An image-forming machine including a main body of the machine having a lower housing and an upper housing mounted on the lower housing pivotably between an open position and a closed position, and a process unit detachably mounted on the lower housing on the main body. The lower housing has a supporting-guiding device mounted pivotably between an elevated position and a lowered position, a holding device pivotably mounted between a holding position at which the supporting-guiding device is held at the elevated position and a release position at which the supporting-guiding device is permitted to move to the lowered position, and a biasing position for elastically biasing the holding device at the holding position. The process unit has a first unit and a second unit. The supporting-guiding device positioned at the elevated position can be mounted on and detached from the first unit. The second unit is separably combined with the first unit.