Abstract: In a fixing device, an alternating current is caused to flow through a coil so as to causes an electrically conductive layer of a rotating member to generate heat, and an unfixed image on a recording medium is heat fixed onto the recording medium by the heat generated by the electrically conductive layer. A frequency range of the alternating current is from 20.5 kHz to 100 kHz. With respect to a generatrix direction of the rotating member, a magnetic member and a spirally shaped portion of the coil have lengths, with which the magnetic member and the spirally shaped portion extend beyond both end portions of the rotating member.

Abstract: Disclosed is a cylindrical rotary member including a conductive layer; a coil disposed inside the rotary member, the coil including a helical portion having a helical axis that is substantially parallel to a generatrix direction of the rotary member, the coil forming an alternating magnetic field to generate heat in the conductive layer by electromagnetic induction; a core disposed inside the helical portion, the core inducing a line of magnetic force of the alternating magnetic field; a roller coming in contact with an outer surface of the rotary member to form a fixing nip portion; and a metal stay disposed inside the rotary member, in which an image on a recording material is fixed to the recording material by being heated at the fixing nip portion and the stay is disposed outside the coil and has a shape that does not form an electrical loop around the coil.

Abstract: The power supply device includes a transformer, a switching unit for driving a primary side of the transformer, a detection unit for detecting an output corresponding to a current flowing on the primary side, a transmission unit for transmitting an output voltage from a secondary side to the primary side, and a control unit for controlling an operation of the switching unit in accordance with an output from the transmission unit, in which, when a switching frequency for driving the switching unit falls within a predetermined frequency range including a resonant frequency of the transformer, the control unit controls the switching unit so as to shorten a turn-ON time of the switching unit in accordance with an output from the detection unit.

Abstract: In a power supply, a synchronous rectification switch rectifies a pulse voltage, and a current-voltage conversion unit converts a current on a voltage-input side of the synchronous rectification switch to a first voltage and converts a current on a voltage-output side of the synchronous rectification switch to a second voltage. A switching unit switches an operation state of the synchronous rectification switch based on a result of a comparison between the first voltage and the second voltage converted by the current-voltage conversion unit. A state holding unit holds an off state after the synchronous rectification switch is turned off by the switching unit.

Abstract: A fixing device configured to fix an image on a recording material, includes: a rotary member including an electroconductive layer; a coil which has a spiral shaped portion and is disposed in the inside of the rotary member; and a core disposed in the spiral shaped portion; with magnetic resistance of the core being, with an area from one end to the other end of the maximum passage region of the image on the recording material regarding the generatrix direction, equal to or smaller than 30% of combined magnetic resistance made up of magnetic resistance of the electroconductive layer and magnetic resistance of a region between the electroconductive layer and the core.

Abstract: The power supply device includes a transformer, a switching unit for driving a primary side of the transformer, a detection unit for detecting an output corresponding to a current flowing on the primary side, a transmission unit for transmitting an output voltage from a secondary side to the primary side, and a control unit for controlling an operation of the switching unit in accordance with an output from the transmission unit, in which, when a switching frequency for driving the switching unit falls within a predetermined frequency range including a resonant frequency of the transformer, the control unit controls the switching unit so as to shorten a turn-ON time of the switching unit in accordance with an output from the detection unit.

Abstract: A discharging circuit includes a filter unit connected between the input lines of a commercial AC power supply, a switch whose operations are controlled by the filter unit; and a discharging unit which discharges voltage of the capacitance element when the switch unit is turned on.

Abstract: The power supply apparatus includes a transformer, a switch element that drives a primary side of the transformer, and a control unit that controls a drive frequency of the switch element, wherein when a state of driving the switch element at a first drive frequency is shifted to a state of driving the switch element at a second drive frequency lower than the first drive frequency, the control unit turns on the switch element at a first timing in which a displacement amount of the transformer caused by the drive of the transformer becomes a first displacement amount and at a second timing in which the displacement of the transformer becomes a second displacement amount smaller than the first displacement amount.

Abstract: In a switching power source, in a state where a second voltage smaller than a first voltage is output from an output unit by intermittently driving a switching unit, the switching unit changes a number of driving times of the switching unit for each driving cycle when the switching unit is intermittently driven.

Abstract: The power supply apparatus includes a transformer having a primary and secondary sides, a first line and a second line to which an AC voltage is input from an AC power supply, a rectifying and smoothing unit that rectifies and smoothes the AC voltage, a shut-off unit provided between the first line and the rectifying and smoothing unit, a switching element that switches a current from the rectifying and smoothing unit to the primary side of the transformer, a first overvoltage detection unit that outputs a voltage corresponding to the AC voltage, a second overvoltage detection unit that outputs an overvoltage detection signal; and a control unit that controls the shut-off unit to shut off the input of the AC voltage.

Abstract: In a switching power source, an OFF-period of switching is set according to a resonance cycle when a transformer is driven.

Abstract: A power supply device controls drive of a synchronous rectification switch unit by converting a voltage into a current, and comparing a voltage obtained by current-to-voltage conversion with a predetermined value.

Abstract: The power supply apparatus for obtaining a direct current from an alternating voltage source includes a first DC/DC converter for outputting a first direct current and a second DC/DC converter for a second direct current lower than the first direct current from the first DC/DC converter, and the output voltage of the first DC/DC converter is changed to a lower direct current and the second DC/DC converter is driven in a continuously-conducting state.

Abstract: The power supply device includes a transformer, a switching unit for driving a primary side of the transformer, a control unit for outputting a pulse signal to the switching unit to control a switching operation including a period during which the switching unit is active and a period during which the switching unit is inactive, in order to output predetermined electric power from a secondary side of the transformer, and an output control unit for continuously outputting a pulse signal to the control unit in the period during which the switching unit is active, at a predetermined cycle shorter than the period during which the switching unit is inactive.

Abstract: The power supply device includes a transformer, a switching unit for driving a primary side of the transformer, a detection unit for detecting an output corresponding to a current flowing on the primary side, a transmission unit for transmitting an output voltage from a secondary side to the primary side, and a control unit for controlling an operation of the switching unit in accordance with an output from the transmission unit, in which, when a switching frequency for driving the switching unit falls within a predetermined frequency range including a resonant frequency of the transformer, the control unit controls the switching unit so as to shorten a turn-ON time of the switching unit in accordance with an output from the detection unit.

Abstract: The power supply apparatus for obtaining a direct current from an alternating voltage source includes a first DC/DC converter for outputting a first direct current and a second DC/DC converter for a second direct current lower than the first direct current from the first DC/DC converter, and the output voltage of the first DC/DC converter is changed to a lower direct current and the second DC/DC converter is driven in a continuously-conducting state.

Abstract: A synchronous rectification power supply controls driving of a switching unit in such a manner as to start the driving in response to rising of an output voltage at a secondary side of a transformer and to stop the driving after a predetermined time passed.

Abstract: In a switching power source, in a state where a second voltage smaller than a first voltage is output from an output unit by intermittently driving a switching unit, the switching unit changes a number of driving times of the switching unit for each driving cycle when the switching unit is intermittently driven.

Abstract: A discharging circuit includes a filter unit connected between the input lines of a commercial AC power supply, a switch whose operations are controlled by the filter unit; and a discharging unit which discharges voltage of the capacitance element when the switch unit is turned on.

Abstract: The transformer includes: first and second cores each including a magnetic center leg and a magnetic outer leg positioned outside of the magnetic center leg; a first adhesion part that adheres the magnetic center leg of the first core and the magnetic center leg of the second core to each other; a second adhesion part that adheres the magnetic outer leg of the first core and the magnetic outer leg of the second core to each other; a bobbin inserted through the magnetic center leg of the first core and the magnetic center leg of the second core, a primary coil and a secondary coil being wound on the bobbin; and an elastic member that applies pressure to the magnetic outer leg of the first core and the magnetic outer leg of the second core in a neighborhood of the second adhesion part, in an inward direction of the transformer.