Abstract: A sheet thickness detection device capable of accurately detecting a thickness of sheets of various types. In a case that information about sheets stored in a sheet feed unit is set by a user through an operation unit or through an external host PC, a CPU of the sheet thickness detection device sets a pressure changeover solenoid to ON to obtain a strong nip pressure between a detection roller and a fixed roller, if a sheet basis weight specified in the information about sheets is larger than a predetermined value, and sets the pressure changeover solenoid to OFF to obtain a weak nip pressure, if the sheet basis weight specified in the information about sheets is equal to or less than the predetermined value.

Abstract: An image forming apparatus capable of accurately detecting a thickness of various sheets. A CPU of the image forming apparatus sets the degree of amplification to a large value, if a sheet basis weight is equal to or less than a threshold value, and sets the degree of amplification to a small value, if the sheet basis weight is larger than the threshold value. One of magnetic sensors, which are disposed facing respective ones of magnets mounted to a displacement member of a sheet thickness detection device of the image forming apparatus, is selected according to the set degree of amplification. When a sheet passes through a detection part of the displacement member, a displacement of the detection part amplified through the displacement member is detected by the selected sensor and a sheet thickness is detected based on an output of the sensor.

Abstract: A sheet feeding apparatus includes a back end detecting sensor which detects a back end side in a conveying direction of the topmost sheet stacked on the sheet tray, a front end detecting sensor which detects a front end side in the conveying direction of the topmost sheet, and a CPU. The CPU disables start of a sheet feeding operation of a feeding unit in a case where the back end detecting sensor and the front end detecting sensor do not detect the sheet when the sheet tray is lifted toward the feeding unit and then stopped in a predetermined position. Accordingly, a state that a feeding failure is possibly caused is detected before feeding the sheets so as to eliminate the wasteful feeding operation.

Abstract: An image forming apparatus has a switch-back conveying portion to convey a sheet conveyed through either a first conveying path or a second conveying path as being switched-back, a mode in which a sheet passed through the first conveying path is conveyed to the second conveying path as being switched-back by the switch-back conveying portion and a mode in which a sheet passed through the second conveying path is conveyed to the first conveying path as being switched-back by the switch-back conveying portion are selectively performed.

Abstract: An image forming system capable of controlling a handover timing of sheets between an image forming apparatus and a sheet feeding apparatus at high precision. A transmission path transmits information between the image forming apparatus and the sheet feeding apparatus. A signal line transmits a handover signal output from the image forming apparatus to the sheet feeding apparatus. A first control unit transmits the handover signal to the sheet feeding apparatus after transmitting a feeding start request to the sheet feeding apparatus. A second control unit controls the sheet feeding apparatus to convey the sheet to a predetermined position in the sheet feeding apparatus in accordance with a reception of the feeding start request and of conveying the sheet at the predetermined position to the image forming apparatus in accordance with a reception of the handover signal.

Abstract: An original reader which is capable of continuously performing a reading operation for reading images from originals without causing degradation of the quality of the read images, even when a light emitter of an illumination unit or a driving circuit for the light emitter fails. An original illuminating lamp including two LED circuit boards each having eight LED blocks linearly arranged in the main scanning direction of an original illuminates the original. An image sensor reads an image from the original illuminated by the original illuminating lamp. When it is detected that at least one of the LED blocks does not emit light, a CPU performs control such that the light amount of an LED block opposed to the LED block emitting no light is increased to be larger than when it is not detected that at least one of the LED blocks does not emit light.

Abstract: An image forming apparatus including a fixing device for fixing by heat an image formed on a recording material; a heater for heating the fixing device; a controller for controlling electric power supply to the heater, wherein the apparatus is operable in a stand-by mode in which an electric energy consumption of the heater is reduced, wherein in the stand-by mode, the controller continuously supplies the electric power to the heater.

Abstract: An image forming apparatus generates a PWM signal corresponding to input image data and controls a timing of a light source to emit a light beam based on the PWM signal in order to perform tone reproduction. The image forming apparatus includes a data processing unit configured to generate the PWM signal for one pixel based on image data for continuous two pixels in the image data. The data processing unit selects an origin of pulse growth in generation of the PWM signal for one pixel in accordance with the image data for the two pixels to generate the PWM signal.

Abstract: An image forming apparatus has a fixing unit for fixing a toner image formed on a recording material, and a heater, for heating the fixing unit, made of a carbon-based material. In order to detect and expect the life of the heating unit with good accuracy, the image forming apparatus further has a current measuring device for measuring a current passing through the heating unit and a notification device for providing notification of information on a life of the heating unit depending on an output of the current measuring device.

Abstract: An image formation device changes the rotational rate of a polygon motor, i.e. the main-scanning rate, and selects one of pulse width conversion tables when an image formation is performed multiple times on a single sheet of transfer paper. The changing of the main-scanning rate is for preventing inconsistent sizes between a first recorded image and a second recorded image caused by shrinkage of transfer paper. The pulse width conversion tables allow the pulse widths to be modulated.

Abstract: An image formation device changes the rotational rate of a polygon motor, i.e. the main-scanning rate, and selects one of pulse width conversion tables when an image formation is performed multiple times on a single sheet of transfer paper. The changing of the main-scanning rate is for preventing inconsistent sizes between a first recorded image and a second recorded image caused by shrinkage of transfer paper. The pulse width conversion tables allow the pulse widths to be modulated.

Abstract: An image forming apparatus which is capable of eliminating density irregularities of an image formed caused by potential irregularities of the photosensitive member when the drum is irradiated by a beam of constant luminous intensity. A laser driver irradiates a beam modulated based on an image signal onto a photosensitive member. A current controller variably controls a driving current for driving the laser driver. A PWM pulse width converter modulates a pulse width of the beam based on the image signal. A potential sensor measures the potential of the photosensitive member after the photosensitive member is irradiated by a beam having a predetermined luminous intensity. A selector causes the current controller to correct the driving current based on low frequency components of irregularities of the potential and changes a modulation coefficient used for modulating the pulse width based on high frequency components of the irregularities of the potential.

Abstract: An image formation device changes the rotational rate of a polygon motor, i.e. the main-scanning rate, and selects one of pulse width conversion tables when an image formation is performed multiple times on a single sheet of transfer paper. The changing of the main-scanning rate is for preventing inconsistent sizes between a first recorded image and a second recorded image caused by shrinkage of transfer paper. The pulse width conversion tables allow the pulse widths to be modulated.

Abstract: An image forming apparatus generates a PWM signal corresponding to input image data and controls a timing of a light source to emit a light beam based on the PWM signal in order to perform tone reproduction. The image forming apparatus includes a data processing unit configured to generate the PWM signal for one pixel based on image data for continuous two pixels in the image data. The data processing unit selects an origin of pulse growth in generation of the PWM signal for one pixel in accordance with the image data for the two pixels to generate the PWM signal.

Abstract: An image forming apparatus includes fixing means for fixing a toner image formed on a recording material, and heating means, for heating the fixing means, comprising a carbon-based material. In order to detect and expect the life of the heating means with good accuracy, the image forming apparatus further comprises current measuring means for measuring a current passing through the heating means and notification means for providing notification of information on a life of the heating means depending on an output of the current measuring means.

Abstract: An image forming apparatus including fixing means for fixing by heat an image formed on a recording material; heating means for heating the fixing means; control means for controlling electric power supply to the heating means, wherein the apparatus is operable in a stand-by mode in which an electric energy consumption of the heating means is reduced, wherein in the stand-by mode, the control means continuously supply the electric power to the heating means.

Abstract: An image forming apparatus which is capable of eliminating density irregularities of an image formed caused by potential irregularities of the photosensitive member when the drum is irradiated by a beam of constant luminous intensity. A laser driver irradiates a beam modulated based on an image signal onto a photosensitive member. A current controller variably controls a driving current for driving the laser driver. A PWM pulse width converter modulates a pulse width of the beam based on the image signal. A potential sensor measures the potential of the photosensitive member after the photosensitive member is irradiated by a beam having a predetermined luminous intensity. A selector causes the current controller to correct the driving current based on low frequency components of irregularities of the potential and changes a modulation coefficient used for modulating the pulse width based on high frequency components of the irregularities of the potential.

Abstract: An image formation device changes the rotational rate of a polygon motor, i.e. the main-scanning rate, and selects one of pulse width conversion tables when an image formation is performed multiple times on a single sheet of transfer paper. The changing of the main-scanning rate is for preventing inconsistent sizes between a first recorded image and a second recorded image caused by shrinkage of transfer paper. The pulse width conversion tables allow the pulse widths to be modulated.