Abstract: An image forming apparatus comprises an image-forming part; a paper feeding part; a resist part; a rotating body; a detector for detecting the arrival of paper at the resist part; a timer part for measuring a measurement time from when feeding of a second sheet of paper from the paper feeding part is begun to when the detector detects the arrival of the second sheet of paper, and a sheet interval time from when the detector detects the passage of a first sheet of paper immediately preceding the second sheet of paper to when the arrival of the second sheet of paper is detected; and an identifier part for referring to the measurement time, a reference measurement time, the sheet interval time and a reference sheet interval time, and deciding the paper feeding part advancing or delaying the paper feed start timing.

Abstract: An image forming apparatus includes a fixing unit and an apparatus main body. The fixing unit includes a first rotating member, a second rotating member and a fixing nip forming mechanism. The first rotating member is heated by a heating source. The second rotating member faces to the first rotating member. The fixing nip forming mechanism makes the second rotating member pressed to the first rotating member and forms a fixing nip between the first rotating member and second rotating member. To the apparatus main body, the fixing unit is attachably/detachably installed. The apparatus main body includes a nip pressure changing mechanism. The nip pressure changing mechanism presses the fixing nip forming mechanism and changes a pressure of the fixing nip.

Abstract: A sheet size setting device includes a first member and a second member. The first member includes a tubular holing portion having a first area and a second area in an axial direction. The second member is assembled with the first member movably in the axial direction of the tubular holding portion and includes a second indicator and a second detectable portion. A movement of the second member in the axial direction is restricted by a restricting portion. The restricting portion restricts the movement of the second member in the axial direction when the tubular holding portion is located at a first rotational position and permits the movement of the second member in the axis direction, thereby causing the second indicator to reach the first area and the second detectable portion to reach the second area, when the tubular holding portion is located at a second rotational position.

Abstract: An image forming apparatus comprises an image-forming part; a paper feeding part; a resist part; a rotating body; a detector for detecting the arrival of paper at the resist part; a timer part for measuring a measurement time from when feeding of a second sheet of paper from the paper feeding part is begun to when the detector detects the arrival of the second sheet of paper, and a sheet interval time from when the detector detects the passage of a first sheet of paper immediately preceding the second sheet of paper to when the arrival of the second sheet of paper is detected; and an identifier part for referring to the measurement time, a reference measurement time, the sheet interval time and a reference sheet interval time, and deciding the paper feeding part advancing or delaying the paper feed start timing.

Abstract: A sheet size setting device includes a first member and a second member. The first member includes a tubular holing portion having a first area and a second area in an axial direction. The second member is assembled with the first member movably in the axial direction of the tubular holding portion and includes a second indicator and a second detectable portion. A movement of the second member in the axial direction is restricted by a restricting portion. The restricting portion restricts the movement of the second member in the axial direction when the tubular holding portion is located at a first rotational position and permits the movement of the second member in the axis direction, thereby causing the second indicator to reach the first area and the second detectable portion to reach the second area, when the tubular holding portion is located at a second rotational position.

Abstract: An image forming apparatus includes an image forming unit, a sheet feeding unit for feeding a sheet, a registration roller for transporting the sheet toward the image forming unit, a rotational member for transporting the sheet toward the registration roller, at least one detection member provided on an upstream side of the registration roller, and a sheet size detection unit configured to receive an output from the detection member. The rotational member is configured to continue rotation until transportation of the sheet is completed. The registration roller is configured to rotate when a predetermined waiting time period has elapsed since the detection member detects sheet arrival. The sheet size detection unit is configured to detect a size of the sheet using a time period from a time when the detection member detects the sheet arrival to a time when the detection member detects sheet passage.

Abstract: An image forming apparatus including an image forming unit forming an image on a recording paper, a registration roller transporting the recording paper to the image forming unit, a post-registration roller detection unit provided at a down stream side of the registration roller in a direction in which the recording paper is transported, the post-registration roller detection unit detecting the recording paper transported by the registration roller and a control unit adjusting a timing in which the image forming unit forms the image on the recording paper based on a timing at which the post-registration roller detection unit detects the recording paper.

Abstract: After post-processes have been performed on sheet bundles which have been stacked in a post-processing tray 16, the sheet bundles are alternately shifted in the paper conveyance lateral direction and each of these shifted sheet bundles are conveyed from the post-processing tray 16 to the discharge port by a sheet receiving member 18, and the sheet bundle is discharged in the shifted condition to a paper discharge tray 13 by a pair of discharge rollers 12 which are located at the discharge port. The pair of discharge rollers 12 have an upper discharge roller 22 and an opposing lower discharge roller 24 which open and close freely, and a solenoid for switching between a closed condition which grasps the sheet bundle and an opened condition which does not grasp the sheet bundle. The lower discharge roller 22 and the upper discharge roller 24 are closed by the solenoid 40 at predetermined timing based on the sheet size.