Abstract: The image forming apparatus includes a current detection circuit for detecting an input current from the commercial power supply to the apparatus, in which: when a current detected by the current detection circuit exceeds a predetermined value, a maximum current suppliable to a fixing portion is restricted; and when a temperature of the fixing portion falls below, in a situation where the maximum current suppliable to the fixing portion is restricted, the predetermined temperature lower than a control target temperature, a conveyance interval of a recording material conveyed to the fixing portion is extended. In the image forming apparatus, even when a consumption current of the image forming apparatus is increased during successive image formation, it is capable of controlling the consumption current so as not to exceed a maximum current of a commercial power supply, securing desired fixability, and minimizing decline of image forming performance.

Abstract: A power supply device generates an output voltage by driving a piezoelectric transformer using a frequency signal. The power supply device includes a comparison unit configured to compare an output voltage and a voltage setting signal that sets the output voltage, and a voltage control oscillation unit configured to generate the frequency signal to drive the piezoelectric transformer based on comparison results of the comparison unit. The voltage control oscillation unit generates the frequency signal within a range between the resonant frequency and a spurious resonant frequency closest to the resonant frequency.

Abstract: A power supply unit in an image forming apparatus is provided. The power supply unit includes a piezoelectric transformer, an output voltage detecting circuit which detects the output voltage of the piezoelectric transformer, an output voltage control circuit which controls an output voltage from the piezoelectric transformer, and includes a comparator which receives an output voltage setting signal, together with an output voltage detecting signal fed back from the output voltage detecting circuit, to compare the output voltage setting signal and the output voltage detecting signal. The power supply unit also includes a driving frequency supplying circuit which generates a driving frequency signal of the piezoelectric transformer in accordance with a comparison result by the comparator, and supplies the driving frequency signal to the piezoelectric transformer. The time constant of the output voltage control circuit is longer than the time constant of the output voltage detecting circuit.

Abstract: The image forming apparatus includes a current detection circuit for detecting an input current from the commercial power supply to the apparatus, in which: when a current detected by the current detection circuit exceeds a predetermined value, a maximum current suppliable to a fixing portion is restricted; and when a temperature of the fixing portion falls below, in a situation where the maximum current suppliable to the fixing portion is restricted, the predetermined temperature lower than a control target temperature, a conveyance interval of a recording material conveyed to the fixing portion is extended. In the image forming apparatus, even when a consumption current of the image forming apparatus is increased during successive image formation, it is capable of controlling the consumption current so as not to exceed a maximum current of a commercial power supply, securing desired fixability, and minimizing decline of image forming performance.

Abstract: A power supply device generates an output voltage by driving a piezoelectric transformer using a frequency signal. The power supply device includes a comparison unit configured to compare an output voltage and a voltage setting signal that sets the output voltage, and a voltage control oscillation unit configured to generate the frequency signal to drive the piezoelectric transformer based on comparison results of the comparison unit. The voltage control oscillation unit generates the frequency signal within a range between the resonant frequency and a spurious resonant frequency closest to the resonant frequency.

Abstract: A power supply unit in an image forming apparatus is provided. The power supply unit includes a piezoelectric transformer, an output voltage detecting circuit which detects the output voltage of the piezoelectric transformer, a comparator which receives an output voltage setting signal, together with an output voltage detecting signal fed back from the output voltage detecting circuit, to compare the output voltage setting signal and the output voltage detecting signal, and a driving frequency supplying circuit which generates the driving frequency of the piezoelectric transformer in accordance with a comparison result by the comparator, and supplies the resultant driving frequency to the piezoelectric transformer. The time constant of the output voltage setting signal is longer than the time constant of the output voltage detecting circuit.

Abstract: An optional apparatus for an image forming apparatus which forms an image on a print medium, which is detachably connected to the image forming apparatus and performs predetermined optional processing for a print medium supplied from the image forming apparatus, is provided. The optional apparatus includes a storage battery which can be charged/discharged, an optional processing unit configured to execute the predetermined optional processing upon receiving supply of power at least from the image forming apparatus or from the storage battery, and a switch unit configured to cut off supply of power from the storage battery to the optional processing unit when the optional apparatus is detached from the image forming apparatus or a door of the optional apparatus is opened.

Abstract: An optional apparatus for an image forming apparatus which forms an image on a print medium, which is detachably connected to the image forming apparatus and performs predetermined optional processing for a print medium supplied from the image forming apparatus, is provided. The optional apparatus includes a storage battery which can be charged/discharged, an optional processing unit configured to execute the predetermined optional processing upon receiving supply of power at least from the image forming apparatus or from the storage battery, and a switch unit configured to cut off supply of power from the storage battery to the optional processing unit when the optional apparatus is detached from the image forming apparatus or a door of the optional apparatus is opened.

Abstract: An image forming apparatus including a detector, a write controller, and a light controller. The detector detects, with an optical sensor, an edge of a recording medium in a direction perpendicular to a reading medium convey direction. The write controller shifts an image write position in the direction perpendicular to the recording medium convey direction on the basis of a detection result of the detector. The light controller controls a light emission amount of the optical sensor to set an output of the optical sensor to a predetermined value at a predetermined portion in an area where the detection result of the optical sensor is effective.

Abstract: An object of this invention is to stably correct and control the image write position of a recording medium in a horizontal scanning direction (main scanning direction) at low cost and high precision in an image forming apparatus having a function of detecting the end of a recording medium by a photosensor, and correcting and controlling the image write position in the horizontal scanning direction on the basis of the detection result. In the arrangement of the image forming apparatus according to the present invention, the light amount of a sheet end detection unit is adjusted by itself such that the end of a recording medium can always be detected at an appropriate light amount regardless of the state of the sheet end detection unit. The image write position in a direction (main scanning direction) perpendicular to the recording medium convey direction is corrected and controlled on the basis of a high-precision end detection result.