Abstract: An image forming apparatus provided with a photoreceptor with an internal gear includes the internal gear in a photoreceptor drum, a pinion gear in engagement with the internal gear, and a cleaning unit and a developer unit which apply contact pressure onto the photoreceptor drum. The pinion gear is provided in such an area that a resulting force of the contact pressure respectively applied from the process elements does not cause a distortion of the photoreceptor drum which exceeds an axial backlash determined in initialization according to a distance between axes of the pinion gear and the internal gear. The described arrangement prevents interference between non-driving surfaces of the internal gear and the pinion gear. As a result, a smooth rotary motion of the photoreceptor drum can be ensured, thereby preventing an image defect caused by an unstable rotary motion of the photoreceptor drum.

Abstract: An image forming apparatus provided with a photoreceptor with an internal gear includes the internal gear in a photoreceptor drum, a pinion gear in engagement with the internal gear, and a cleaning unit and a developer unit which apply contact pressure onto the photoreceptor drum. The pinion gear is provided in such an area that a resulting force of the contact pressure respectively applied from the process elements does not cause a distortion of the photoreceptor drum which exceeds an axial backlash determined in initialization according to a distance between axes of the pinion gear and the internal gear. The described arrangement prevents interference between non-driving surfaces of the internal gear and the pinion gear. As a result, a smooth rotary motion of the photoreceptor drum can be ensured, thereby preventing an image defect caused by an unstable rotary motion of the photoreceptor drum.

Abstract: In a paper-punching device for use in an image-forming apparatus, the rear edge of a sheet of paper that is being transported through a transport guide is detected by the photosensor. After a predetermined time has passed since the detection, a punching device is activated. At this time, a punching member is depressed downward, and a punching blade attached to its top penetrates through the sheet of paper, thereby forming a punch hole. Even during the punching operation, transport rollers continue to rotate. Therefore, when the sheet of paper is caught by the punching blade, the transport rollers are allowed to slip predetermined amount with respect to the paper. For this reason, at least one of the transport rollers is made of a foamed material. With this arrangement, since the punching operation is carried out on the rear side of the sheet of paper, it becomes possible to reduce the occurrence of paper jams even if sheets of paper are transported in succession.

Abstract: An image forming apparatus provided with a photoreceptor with an internal gear includes the internal gear in a photoreceptor drum, a pinion gear in engagement with the internal gear, and a cleaning unit and a developer unit which apply contact pressure onto the photoreceptor drum. The pinion gear is provided in such an area that a resulting force of the contact pressure respectively applied from the process elements does not cause a distortion of the photoreceptor drum which exceeds an axial backlash determined in initialization according to a distance between axes of the pinion gear and the internal gear. The described arrangement prevents interference between non-driving surfaces of the internal gear and the pinion gear. As a result, a smooth rotary motion of the photoreceptor drum can be ensured, thereby preventing an image defect caused by an unstable rotary motion of the photoreceptor drum.

Abstract: In a paper-punching device for use in an image-forming apparatus, the rear edge of a sheet of paper that is being transported through a transport guide is detected by the photosensor. After a predetermined time has passed since the detection, a punching device is activated. At this time, a punching member is depressed downward, and a punching blade attached to its top penetrates through the sheet of paper, thereby forming a punch hole. Even during the punching operation, transport rollers continue to rotate. Therefore, when the sheet of paper is caught by the punching blade, the transport rollers are allowed to slip a predetermined amount with respect to the paper. For this reason, at least one of the transport rollers is made of a foamed material. With this arrangement, since the punching operation is carried out on the rear side of the sheet of paper, it becomes possible to reduce the occurrence of paper jams even if sheets of paper are transported in succession.

Abstract: A copying machine capable of continuously copying two or more one-side subject copies on both sides of copying sheets, includes a rotary drum housing (32) for passing two or more subject copies through a light scan window (43) of an optical system (35), a paper cassettes (52) disposed in the rotary drum housing for feeding the copying sheets to the optical system, a reversing roller (62) coupled to the rotary drum housing for reversing the copying sheets having images formed by the optical system on one sides, a middle tray (55) coupled to the rotary drum housing for refeeding the reversed copying sheets to the optical system, sensors (S1-Si) connected to the rotary drum housing for detecting a number of the subject copies passing through the rotary drum housing, and a microcomputer (103) connected to the rotary drum housing for controlling the rotary drum housing so that the subject copies pass through the light scan window of the optical system sequentially in circulation from a final page to a first page.

Abstract: A sheet treatment device comprises an unit for counting the number of sheets conveyed piece by piece from an image forming device, an unit for binding a plurality of sheets counted by the counting unit, an unit for conveying a set of sheets bound by the binding unit, an unit for setting a time period associated with the number of sheets counted by the counting unit, an unit, which is disposed at a specified position, for detecting passage of the set of sheets conveyed by the conveying unit, and an unit for judging that sheet jamming has occurred in the event that the passage is not detected by the detecting unit within the time period from the time when the set of sheets begins to be conveyed by the conveying unit.

Abstract: An automatic original document feeder is provided which feeds an original document placed on an original document table so as to invert the original document thus fed through an inverting transport section for its transport to an image exposing position with an image surface of the original document being inverted. A transport belt is provided for feeding the original document into the inverting transport section, and an original document stopper is provided for stopping the original document transported by the transport belt once at a position before it is fed into the inverting transport section in order to again transport, by the transport belt, the original document stopped by the original document stopper so as to be fed into the inverting transport section for transporting the inverted original document to the image exposing position.