Abstract: A processing apparatus that an uninterruptible power supply system supplies power to and carries out a process. The processing apparatus includes an electric energy amount determination part that determines, based on a charged amount of electric energy in the uninterruptible power supply system, an amount of maximum electric energy that the uninterruptible power supply system can supply; and a function selection part that selects, depending on the amount of maximum electric energy, functions that can be used for carrying out the process.

Abstract: An image forming apparatus includes an image carrier, a charging unit, an exposure unit, a developing unit, and a transfer unit. The transfer unit includes a transfer bias power supply and transfers a developed image onto a transfer body. The transfer bias power supply includes a first power supply unit that generates a non-transfer electric field, a second power supply unit that generates a transfer electric field, a first switching controller, and a second switching controller. The first switching controller controls start of supply of the transfer electric field in accordance with a first time constant when switching from the non-transfer electric field to the transfer electric field is performed. The second switching controller controls stop of supply of the transfer electric field in accordance with a second time constant when switching from the transfer electric field to the non-transfer electric field is performed.

Abstract: An image processing apparatus, a method of controlling a power save state of the image processing apparatus, and a non-transitory recording medium storing a power save control program are provided. In response to detection of a power save transition factor that triggers transition to a power save state, the image processing apparatus determines whether a power save extension factor is detected, extends transition to the power save state at least during when the power save extension factor is being detected, and causes transition to the power save state according to the detected power save transition factor when the power save extension factor is not detected.

Abstract: A power switch structure for an apparatus, including a recess provided in a side surface of the apparatus and having a distal sloped face facing a front side of the apparatus and a proximal sloped face surface, and a power switch, inclined with respect to the side surface of the apparatus, positioned on the distal sloped face surface to face the front side of the apparatus.

Abstract: An image forming apparatus which is capable of extending the life of relay contacts even when a noise filter circuit is disposed downstream of relays on paths over which commercial alternating-current power is supplied. First and second relays disposed in respective ones of two supply paths that are different in polarity, over which power is supplied, and switch supply and shut off of the power. The noise filter circuit filers out noise on the supply paths. When supply of alternating-current power to a power supplied device disposed downstream of the noise filter is started, one of the relays is switched into supply state first, and then the other one is switched into supply state so that the number of times each relay is switched into supply state first per predetermined number of times power is supplied can be substantially equal between the first and second relays.

Abstract: An image forming apparatus that heat-fixes a toner image onto a recording sheet passing through a fixing nip formed by pressing a pressurizing member against a heating rotational body heated by a heater, comprising: a storage unit storing a basic power consumption level of the heater determined in advance in a situation where inflow of inrush current to the heater is not occurring; an estimation unit calculating an estimated power consumption level of the heater by estimating an increase in the power consumption level, with respect to the basic power consumption level, brought about by inflow of inrush current to the heater; and an output unit outputting the estimated power consumption level. The heater switches between a heating state of receiving power supply and a non-heating state of not receiving power supply. The increase is estimated according to a duration of a non-heating state immediately preceding the heating state.

Abstract: An image processing apparatus is provided that includes plural devices, a device control unit associated with each of the devices for controlling a power status of each of the devices according to a relevant power mode, and power mode setting unit for setting the relevant power mode to the device control unit.

Abstract: An image forming apparatus includes a power supply unit to generate DC power, a plurality of function units to perform the functions of the image forming apparatus, a control unit to control the operation of a plurality of function units, a switching unit to receive DC power of the power supply unit and switch power provided to the control unit and each of a plurality of function units, and a power management unit to receive DC power of the power supply unit and to control a switching operation of the switching unit according to an operation mode of the image forming apparatus.

Abstract: This invention allows completely cutting power supply to a circuit that has become dysfunctional because of blowout of a fuse. To accomplish this, a circuit includes a fuse connected to one supply line of an AC power supply, a switching unit connected to the other supply line of the AC power supply, a detection unit configured to detect blowout of the fuse, and a control unit configured to turn off the switching unit when the detection unit detects blowout of the fuse.

Abstract: A power supply system includes: a switching power supply and a rectifying/smoothing circuit, the switching power supply configured to output a first output voltage in a normal output mode; a step-down circuit; a control device that controls the switching of the switching power supply between the normal output mode, a low output mode, and an off mode; and an electric storage unit charged by the output of the step-down circuit in the normal output mode and supplies power to the control device in the off mode, wherein, when charging is needed in the mode other than the normal output mode and the low output mode, the control device controls the switching power supply to output the third output voltage, thereby charging the electric storage unit.

Abstract: The voltage detection device includes a first voltage detection part for detecting whether or not a time period ratio during which a voltage of an AC power supply is equal to or larger than a first threshold value is equal to or larger than a first ratio and a second voltage detection part for detecting whether or not a time period ratio during which the voltage of the AC power supply is lower than the first threshold value and equal to or larger than a second threshold value is equal to or larger than a second ratio higher than the first ratio, and determines whether the voltage of the AC power supply is a first commercial voltage or a second commercial voltage lower than the first commercial voltage based on results obtained by the first voltage detection part and by the second voltage detection part.

Abstract: An image forming apparatus is configured to electro-photographically form an image and includes a main body frame which includes a side wall, an outer cover which covers an outer face of the main body frame, a high-voltage board which includes a high-voltage generator circuit configured to generate a high voltage and supply an electric power to a device requiring a high-voltage power source, and a main board which includes a main control circuit configured to perform a control on an image forming process of the image forming apparatus. In a side region which is formed by the side wall of the main body frame and the outer cover, the high-voltage board and the main board are disposed along the side wall to overlap with each other at least partially, and the high-voltage board is disposed on an outer side relative to the main board.

Abstract: When a detection signal indicates that a switch has switched off, a first relay cuts off the supply of alternating current from a commercial alternating-current source to a third DC power source and terminates a first load such as a motor and a high-voltage power source. When the detection signal indicates that the switch has switched off, a control circuit executes shutdown processing for safely terminating an operation of a second load such as a hard disk drive. When the shutdown processing is complete, the control circuit outputs a signal for terminating an operation of a second DC power source. When the shutdown signal is input, a second relay terminates the operation of the second load by cutting off the supply of the alternating current from the commercial alternating-current source to a second DC power source.

Abstract: An image forming apparatus includes a fixing portion including an endless belt, a heater, a back-up member, the heater including first heat generating elements; and a controller for controlling power supplied to the first element and the second element in accordance with a temperature of the fixing portion; wherein the power controller supplies the power to the first element and the second element so that a feeding speed V1 of the sheet at the fixing nip, a distance A between the first element and the second element, a ratio Pin % of total power supplied to the first element and the second element set in accordance with the temperature of the fixing portion, a ratio E203(t) % of power supplied to the first element at timing t, and a ratio E204(t) % of power supplied to the second element at timing t the following equation, E203(t)+E204(t)+(A/V1))Pin.

Abstract: An image forming device includes: a processing unit that performs an image forming process on a sheet; a housing that defines a housing space in which the processing unit is housed; a high-voltage board that generates a high voltage to be supplied to the processing unit; a wire that electrically connects the high-voltage board and the processing unit with each other; and a wire holding plate that holds the wire. The housing includes a pair of a first sheet-metal frame and a second sheet-metal frame which oppose each other and a sheet-metal coupling piece which couples these sheet-metal frames, and the first sheet-metal frame and the second sheet-metal frame support the processing unit between the first sheet-metal frame and the second sheet-metal frame. The wire holding plate extends over substantially the entire dimension of the coupling piece in an extending direction thereof and is fixed to the coupling piece.

Abstract: An image forming apparatus includes: an image carrier; a toner image forming unit that forms a toner image on the image carrier; a transfer unit that transfers the toner image on the image carrier to a transfer target having ridges and valleys on a surface thereof; an adjusting unit that adjusts a ratio of A/B, where A is a transfer ratio [%] from the image carrier to a valley portion of the transfer target while B is a transfer ratio [%] from the image carrier to a ridge portion of the transfer target, based on an adjustment input by a user; and a control unit that controls a transfer condition of the transfer unit based on the ratio of A/B adjusted by the adjusting unit.

Abstract: A power control system includes an image forming apparatus, a power calculating unit, and a condition controller. The image forming apparatus operates using power, forms an image corresponding to image information in a first operation mode, and enters a second operation mode in which power consumption is smaller than the first operation mode when the image forming apparatus satisfies a specific transition condition. The power calculating unit calculates power supplied from a power supplying unit. The condition controller controls the specific transition condition for the image forming apparatus in accordance with the power calculated by the power calculating unit.

Abstract: An image forming apparatus includes a rotatable image bearing member including an electroconductive base member and a photosensitive member formed on the electroconductive base member; a contact charging device for electrically charging the photosensitive member; a DC voltage applying device for applying a DC voltage to the contact charging device; an exposure device for exposing the charged photosensitive member to light; and a current detecting device for detecting a current passing from the contact charging device to the electroconductive base member of the image bearing member.

Abstract: A developing device includes a developing unit having a developing frame defining therein a developing chamber and a developing roller rotatably disposed in the developing chamber, and a developing agent unit including a developing agent container that accommodates therein a developing agent, and an agitator disposed in the developing agent container and rotatable about a rotation axis in a rotational direction to agitate the developing agent. The developing agent container includes an arcuate bottom wall whose center of radius of a curvature is coincident with the rotation axis, and an arcuate protruding wall protruding from the bottom wall toward the developing chamber and positioned downstream of the bottom wall in the rotational direction. The protruding wall is formed with an opening providing a fluid communication between an interior of the developing agent container and the developing chamber. The opening has a downstream end in the rotational direction in an operational state.

Abstract: A power supply includes a transformer, a switching unit configured to drive the transformer at a primary side of the transformer, a voltage adjustment unit configured to adjust voltage of a capacitive element at a secondary side of the transformer, at the primary side thereof, and a plurality of constant voltage members connected across the terminals of the capacitive element at the secondary side of the transformer, wherein the power supply generates voltage having a predetermined polarity during the period before the voltage of the capacitive element at the secondary side of the transformer becomes a predetermined voltage by the voltage adjustment unit, and generates voltage having a polarity opposite to the predetermined polarity after the voltage of the capacitive element at the secondary side becomes the predetermined voltage.

Abstract: An image forming apparatus includes a photosensitive member, an exposure unit configured to expose the photosensitive member corresponding to an image, a developing unit configured to develop, using a toner, an electrostatic latent image formed on the exposed photosensitive member, a generation unit configured to generate a waveform signal for the developing unit, a parallel-to-serial conversion unit configured to apply, at a predetermined sampling period, parallel-to-serial conversion to a plurality of signals including the generated waveform signal, a serial-to-parallel conversion unit configured to apply, at the predetermined sampling period, serial-to-parallel conversion to the signals output from the parallel-to-serial conversion unit, and a voltage applying unit configured to apply to the developing unit a voltage composed of a direct-current voltage and an alternating-current voltage superimposed thereon based on the waveform signal among signals output from the serial-to-parallel conversion unit.

Abstract: An image forming apparatus includes a fuser unit configured to make an image fused to a recording medium, a selecting unit configured to select a duplex scanning mode or a single-side scanning mode, a check unit configured to determine which one of the duplex scanning mode and the single-side scanning mode is selected, a duplex scanning unit configured to perform a scan when both sides of a document sheet are scanned upon the duplex scanning mode being selected, a setting unit configured to determine power supplied to the fuser unit upon determining, by the check unit, that the single-side scanning mode is selected, and a supply unit configured to supply the determined power to the fuser unit, wherein the determined power is equal to a sum of power consumed by the duplex scanning unit and power that is consumed by the fuser unit upon the duplex scanning mode being selected.

Abstract: An image forming apparatus which is capable of reducing the number of times a second member is separated from a first member upon entry into power-save mode, thereby minimizing failures of a separation unit. A pressure-roller separating mechanism is provided so as to abut and separate a pressure roller and a fixing roller against/from each other. The image forming apparatus is controlled to change to a power-save mode in which power consumption of the image forming apparatus is reduced. The pressure-roller separating mechanism is controlled to separate the pressure roller and the fixing roller from each other in the power-save mode based on a measurement result measured by a timer, and the power-save mode is maintained after the pressure roller and the fixing roller are separated from each other.

Abstract: One aspect of the present invention provides an information processing apparatus comprising: an acquisition unit configured to acquire the print request from the client; a selection unit configured to select the first printing apparatus when the accumulated power consumption is not more than a first threshold, and selects the second printing apparatus when the accumulated power consumption is higher than the first threshold; and an accumulation unit configured to add a power to be consumed by the printing apparatus selected by the selection unit to process the print request to the accumulated power consumption stored in the storage unit.

Abstract: A power supply apparatus outputs a developing voltage in which a pulse wave shape at a time of positive amplitude is different from a pulse wave shape at a time of negative amplitude. Voltages are supplied from two switching regulators respectively to a bridge circuit for driving a transformer. Here, an absolute value of a difference between a drive frequency of a first switching regulator and a drive frequency of a second switching regulator is configured to be not less than an invisible frequency at which a banding cannot be recognized by humans.

Abstract: A converter includes a switching unit configured to switch a voltage to be input, an inductor connected to the switching unit, a conversion unit configured to convert the voltage switched by the switching unit to be supplied to the inductor into a direct current voltage, a detection unit configured to detect the direct current voltage converted by the conversion unit, and a correction unit configured to correct the detected voltage detected by the detection unit, wherein an operation of the switching unit is controlled based on the voltage corrected by the correction unit.

Abstract: One disclosed aspect of the embodiments relates to power control of a heater in a fixing unit. A plurality of control tables having different ratios of phase control waveforms and wave number control waveforms in one control cycle have been set, and a control table is selected depending on a set target temperature.

Abstract: A power supply apparatus includes a first electric power-generating unit that generates an electric power with a first voltage, a second electric power-generating unit that generates an electric power with a second voltage that is higher than the first voltage, and an overcurrent monitoring circuit to which electric powers for operation are supplied from the first electric power-generating unit and the second electric power-generating unit and that monitors overcurrent in the second electric power-generating unit.

Abstract: A multiple-output power supply unit includes: a first voltage generation circuit that generates a first voltage applied to a first load; a first output terminal that outputs a second voltage corresponding to the first voltage to a second load; a first constant voltage element that is connected to the first output terminal; a second constant voltage element that is provided between the first constant voltage element and a ground; and a second output terminal that is connected between the first constant voltage element and the second constant voltage element so as to output a third voltage having a predetermined potential difference from the second voltage to a third load that is provided in a state of being electrically connected to the second load.

Abstract: Part of a plurality of power levels of control patterns selected to control power supplied from an AC power source to a heater of an image forming apparatus include power levels of a) waveforms in which power is supplied in part of negative and positive half cycles in order after no power supply during a one half of a positive half cycle, and waveforms in which power is supplied in part of a positive cycle after no power supply during one half of a negative half cycle, or b) waveforms in which power is supplied in part of positive and negative half cycles in order after no power supply during one half of a negative half cycle, and waveforms in which power is supplied in part of a negative half cycle after no power supply during one half of a positive half cycle.

Abstract: A power supply apparatus needs to control an output voltage to a target voltage for a short time. A power supply apparatus of the present invention detects voltages output from a piezoelectric transformer. The power supply apparatus also detects peak values in a plurality of detected voltages according to a plurality of frequencies of pulse signals for the piezoelectric transformer, and identifies a frequency corresponding to the highest peak value, and a frequency corresponding to a next peak value next to and on a higher- or lower-frequency side of the frequency corresponding to the highest peak value. Moreover, the power supply apparatus sets an initial frequency used when starting to control the output voltage of the piezoelectric transformer to the target voltage, within a frequency range between the two identified frequencies.

Abstract: An image processing apparatus includes an image forming unit, power supplier, power controller, memory, signal transmission unit and transmission timer. The image forming unit forms an image based on image data from a plurality of host devices. The power supplier supplies power to a power system including the image forming unit. The power controller controls the power from the power supplier to the power system. The memory stores a usage amount of each host device. The signal transmission unit transmits a response request to a host device having at least a predetermined usage amount. The transmission timer counts a first time period from a transmission of the response request. The power controller halts the power from the power supplier to the power system when determining, based on the first time period, that a reply to the response request is not transmitted from the specific host device for a predetermined period.

Abstract: A detecting unit detects a usage state of a charge storage unit for each predetermined time period. A setting unit determines whether the usage state of the charge storage unit satisfies a predetermined condition for each time period, and when it is determined that the usage state satisfies the predetermined condition, sets a corresponding time period as a charge-use permitted time. A control unit determines whether a current time falls in the charge-use permitted time, and when it is determined that the current time falls in the charge-use permitted time, allows a discharging unit to discharge the charge storage unit.

Abstract: A multifunctional apparatus comprises a main power board, electricity feed switching section, operating panel and control section. The main power board supplies electric power to a plurality of processing units. The electricity feed switching section allows a user to switch electricity feed status between the main power board and the respective processing units separately. The operating panel displays an icon depicting the apparatus and electricity feed status of the processing units of the apparatus. The control section controls the electricity feed switching section so as to switch electricity feed status to the processing unit of which icon a user touches, and causes to display on the operation panel modes of operation associated with the processing unit. The control section controls the electricity feed switching section so as to switch the electricity feed status to one or more processing units associated with the mode of operation that a user has selected.

Abstract: A load driver applies pulse voltages to a first capacitive load that includes a first electrode and a second electrode and a second capacitive load that includes a third electrode and a fourth electrode. The load driver further includes a capacitor, at least one coil, and a driver. The driver connects the second capacitive load, the capacitor, and the coil to release charge from the third electrode to the capacitor, connects, after completion of releasing the charge to the capacitor, the first capacitive load, the second capacitive load, and the coil to release charge from the first electrode to the fourth electrode, connects, after completion of releasing the charge to the fourth electrode, the first capacitive load, the capacitor, and the coil to release charge from the capacitor to the second electrode, whereby the pulse voltages of opposite phases is applied.

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: A power source device includes: a transformer; a switching section driving a primary side of the transformer; and a controller capable of performing a switching operation on driving of the switching section for controlling an output of a secondary side of the transformer. The device detects a drive frequency for the switching section in the switching operation, and switches the drive frequency so as not to be a frequency in a prescribed range when the detected drive frequency reaches a threshold.

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: An image processing apparatus that is operable by AC power and DC power. The image processing apparatus includes a fixing heater section for heating a recording sheet having toner transferred thereon so as to fuse the toner onto the sheet and a plurality of electronic circuits. An AC power supply circuit section receives AC power from an AC power supply line. A DC power supply circuit section receives DC power from a DC power supply line. A power supply unit supplies the AC power received by the AC power supply circuit section to the fixing heater section, and the DC power received by the DC power supply circuit section to the plurality of electronic circuits.

Abstract: An image forming apparatus includes a reading unit, a first control unit, a second control unit, and a power supply control unit. The reading unit reads authentication information including a card type and a user code. The first control unit determines, in a state where power is not being supplied to the second control unit, whether a card type included in the authentication information read by the reading unit corresponds to a predetermined card type. The second control unit requests an authentication apparatus to perform user authentication based on the authentication information read by the reading unit. The power supply control unit controls power supply to the second control unit. In response to the first control unit determining that the card type included in the authentication information read by the reading unit corresponds to the predetermined card type, the power supply control unit supplies power to the second control unit.

Abstract: An image forming apparatus having a first mode for operation with predetermined power consumption and a second mode for operation with less power consumption than the power consumption in the first mode includes: a paper cassette capable of being attached to a predetermined section of the image forming apparatus, the paper cassette storing paper therein; a detection part detecting the attachment and detachment of the paper cassette to and from the predetermined section; and a shift part, upon the detection by the detection part that the paper cassette has been attached to the predetermined section during the operation in the second mode, shifting the image forming apparatus from the second mode to the first mode.

Abstract: An image forming apparatus includes a printing engine to form an image on a printing medium through printing processes, an engine frame to support the printing engine having a driving system to drive the printing engine, a high voltage power supply provided in a surface of the engine frame to apply a high voltage to at least one of units performing the printing processes, a main board provided in a surface of the engine frame adjacent to the surface having the high voltage power supply, and having a system engine controller to control the printing engine and a video controller to control a video signal, first and second main connectors respectively provided at lateral sides of the high voltage power supply and the main board adjacent to each other, and a connection control line to connect the first and second main connectors.

Abstract: Disclosed is a power supply including a first voltage generating unit that generates a first voltage from an external power supply; a second voltage generating unit that generates a first predetermined voltage and supplies the generated first predetermined voltage to the load; a third voltage generating unit that generates the first predetermined voltage and supplies the generated first predetermined voltage to the load; and a controller that causes the first voltage to be greater than or equal to a second voltage during a first mode, and causes the first voltage to be less than the second voltage during a second mode. During the first mode, the power is supplied from the second voltage generating unit and the third voltage generating unit to the load, and during the second mode, the power is supplied from the third voltage generating unit to the load.

Abstract: A heater controller performs on/off control of a plurality of heaters and includes a storage unit that stores therein a plurality of pattern sets. Each of the pattern sets includes a plurality of heater-on/off patterns for respectively controlling the heaters. The heater controller calculates a reference value representing an average of values of electric power supplied to the heater controller over a predetermined period of time; calculates, for each of the pattern sets, an output power value to be supplied to the heaters when the heaters are turned-on according to the heater-on/off patterns included in the pattern set; calculates, for each of the pattern sets, a difference between the reference value and the output power value; selects, from the pattern sets, one pattern set having a smallest difference; and performs on/off control of the heaters according to the heater-on/off patterns included in the pattern set thus selected.

Abstract: A color multifunction printer as an example of an image forming apparatus includes a plurality of cartridges each containing a photoconductor; a support frame configured to support the cartridges arranged in tandem, the support frame being allowed to be pulled out horizontally from a casing of the apparatus to a position in which each of the cartridges is detachable from the support frame; and a plurality of exposure units mounted to the support frame, wherein each of the exposure units is disposed opposite to a corresponding photoconductor and is configured to expose the photoconductor to light to form an electrostatic latent image thereon. Each of the cartridges is configured to be detachable in such a direction that the photoconductor in the cartridge moves away from the corresponding exposure unit upon detachment.

Abstract: A method of controlling a power save mode of an image forming apparatus connected to a host apparatus, the method includes: requesting information on a power mode of the image forming apparatus; transmitting the power mode information and information on an entering time for a power save mode of the image forming apparatus from the image forming apparatus; and displaying the entering time for the power save mode of the image forming apparatus on a basis of the entering time information.

Abstract: An image forming apparatus including a fixing device using an induction heating method determines a driving frequency for a switching element configured to drive an induction coil, according to a difference between a detected temperature of an electrically conductive heating element provided in the fixing device and a target temperature. When the determined frequency is a predetermined minimum frequency and a current flowing through the induction coil is at a predetermined value or less, the image forming apparatus generates a signal indicating the abnormality of electric power supplied to the induction coil.

Abstract: A high-voltage power supply comprises the following components. A piezoelectric transformer outputs a voltage in accordance with a supplied drive frequency. A rectification part is connected to an output side of the piezoelectric transformer. A drive frequency generating part generates the drive frequency supplied to the piezoelectric transformer. A voltage detection part detects an output voltage of the piezoelectric transformer or the rectification part. A control part controls the drive frequency generating part such that a drive frequency corresponding to the output voltage detected by the voltage detecting part is generated. A first time constant, which is a time constant of the control part, is smaller than a second time constant, which is a time constant of a control target including the piezoelectric transformer and the rectification part. A third time constant, which is a time constant of the voltage detecting part, is smaller than the second time constant.

Abstract: An image forming apparatus for controlling power supply is provided. An image forming apparatus includes at least one cover unit to be mounted in the image forming apparatus, at least one replaceable unit to participate in an image forming operation of the image forming apparatus, a sensing unit to sense whether the at least one cover unit is opened or closed, and a main board unit to cut off the power supply to the at least one replaceable unit for a predetermined period of time when the at least one cover unit is opened or closed. Accordingly, stable operation is enabled.

Abstract: A heating device includes: a heat generating unit generating heat in response to energization of an alternating-current power supply; a zero-crossing signal generating circuit generating a zero-crossing signal in synchronization with a zero-crossing time of the alternating-current power supply; an energization regulating unit regulating an energization period of the heat generating unit by the alternating-current power supply; a voltage change rate detecting unit detecting whether a rate of voltage change of the alternating-current power supply at the zero-crossing time is equal to or larger than an predetermined value; a switching unit switching on and off a connection between the alternating-current power supply and the heat generating unit; and an energization disabling unit disabling energization of the heat generating unit by controlling the switching unit when the rate of voltage change is equal to or larger than the predetermined value.