Abstract: An image forming apparatus includes a fixing unit including a heater; a bidirectional thyristor for supplying electric power form an AC power source to the heater in a conduction state and for cutting off supply of the electric power from the AC power source to the heater in a non-conduction state; a control unit for outputting a control signal for controlling the conductive state or the non-conduction state of the bidirectional thyristor; and a DC voltage source for supplying electric power for conduction of the bidirectional thyristor by the control signal outputted from the control unit. The control unit controls the heater in a predetermined control cycle on a one half-wave unit basis of an AC voltage of the AC power source. The control unit outputs a plurality of control signals in one half-wave of the AC voltage.

Abstract: An image forming apparatus includes a fixing unit including a heater; a bidirectional thyristor for supplying electric power form an AC power source to the heater in a conduction state and for cutting off supply of the electric power from the AC power source to the heater in a non-conduction state; a control unit for outputting a control signal for controlling the conductive state or the non-conduction state of the bidirectional thyristor; and a DC voltage source for supplying electric power for conduction of the bidirectional thyristor by the control signal outputted from the control unit. The control unit controls the heater in a predetermined control cycle on a one half-wave unit basis of an AC voltage of the AC power source. The control unit outputs a plurality of control signals in one half-wave of the AC voltage.

Abstract: An energization control device includes a voltage detection unit, a control portion, and an energization switching unit. The control portion to which the first detection signal and the second detection signal are input from the voltage detection unit is configured to output a first energization signal if the first detection signal is input and output a second energization signal if the second detection signal is input. The control portion is configured to obtain a correction value based on a difference between a first period in which the first detection signal is input to the control portion and a second period in which the second detection signal is input to the control portion and to correct a timing of switching between the first energization signal and the second energization signal with the correction value.

Abstract: In a case where a drive instruction signal in a high level for placing a first triac provided to correspond to a heat generation member in a conduction state is output from a CPU, the first triac is placed in a conduction state after a second triac provided to correspond to a heat generation member is prohibited from being in a conduction state. In a case where a drive instruction signal in a low level for placing the second triac in a non-conduction state is output from the CPU, the state in which the second triac is prohibited from being in the conduction state is released after the first triac is placed in the non-conduction state.

Abstract: An energization control device includes a voltage detection unit, a control portion, and an energization switching unit. The control portion to which the first detection signal and the second detection signal are input from the voltage detection unit is configured to output a first energization signal if the first detection signal is input and output a second energization signal if the second detection signal is input. The control portion is configured to obtain a correction value based on a difference between a first period in which the first detection signal is input to the control portion and a second period in which the second detection signal is input to the control portion and to correct a timing of switching between the first energization signal and the second energization signal with the correction value.

Abstract: In a case where fixing processing ends in a state where a power supply line is switched by a switching unit according to a first print command so that power is suppliable to a second heating element, the switching unit switches the power supply line from the second heating element to a first heating element so that power is suppliable to the first heating element, the switching occurring regardless of presence or absence of reception of a second print command subsequent to the first print command.

Abstract: In a case where a drive instruction signal in a high level for placing a first triac provided to correspond to a heat generation member in a conduction state is output from a CPU, the first triac is placed in a conduction state after a second triac provided to correspond to a heat generation member is prohibited from being in a conduction state. In a case where a drive instruction signal in a low level for placing the second triac in a non-conduction state is output from the CPU, the state in which the second triac is prohibited from being in the conduction state is released after the first triac is placed in the non-conduction state.

Abstract: In a case where fixing processing ends in a state where a power supply line is switched by a switching unit according to a first print command so that power is suppliable to a second heating element, the switching unit switches the power supply line from the second heating element to a first heating element so that power is suppliable to the first heating element, the switching occurring regardless of presence or absence of reception of a second print command subsequent to the first print command.

Abstract: In a case where fixing processing ends in a state where a power supply line is switched by a switching unit according to a first print command so that power is suppliable to a second heating element, the switching unit switches the power supply line from the second heating element to a first heating element so that power is suppliable to the first heating element, the switching occurring regardless of presence or absence of reception of a second print command subsequent to the first print command.

Abstract: In a case where fixing processing ends in a state where a power supply line is switched by a switching unit according to a first print command so that power is suppliable to a second heating element, the switching unit switches the power supply line from the second heating element to a first heating element so that power is suppliable to the first heating element, the switching occurring regardless of presence or absence of reception of a second print command subsequent to the first print command.

Abstract: A fixing apparatus includes a tubular film and a heater in contact with an inner surface of the film. The heater includes a long thin substrate, a first heat generation resistor extending in a longitudinal direction of the substrate, a second heat generation resistor extending in the longitudinal direction of the substrate, and a conductor electrically connecting the first heat generation resistor and the second heat generation resistor to each other. At least part of the conductor is disposed in an area, in the longitudinal direction, in which the first heat generation resistor is disposed. In a range of 25° C. to 900° C., the conductor has a resistance lower than a total resistance of the first heat generation resistor and the second heat generation resistor. The conductor has a temperature coefficient of resistance larger than a temperature coefficient of resistance of the first heat generation resistor.

Abstract: A fixing apparatus includes a tubular film and a heater in contact with an inner surface of the film. The heater includes a long thin substrate, a first heat generation resistor extending in a longitudinal direction of the substrate, a second heat generation resistor extending in the longitudinal direction of the substrate, and a conductor electrically connecting the first heat generation resistor and the second heat generation resistor to each other. At least part of the conductor is disposed in an area, in the longitudinal direction, in which the first heat generation resistor is disposed. In a range of 25° C. to 900° C., the conductor has a resistance lower than a total resistance of the first heat generation resistor and the second heat generation resistor. The conductor has a temperature coefficient of resistance larger than a temperature coefficient of resistance of the first heat generation resistor.

Abstract: An image heating apparatus includes a rotary member, a heating member configured to heat the rotary member, the heating member being held in contact with the rotary member, a temperature detecting element configured to detect the temperature of the rotary member or the heating member, a protection element configured to interrupt power supply to the heating member, the protection element being activated when sensing an abnormal rise in the temperature of the heating member, and a control portion configured to control the image heating apparatus. When the temperature detected by the temperature detecting element exceeds a threshold value, the control portion stops rotation of the rotary member.

Abstract: An image heating apparatus, including: a rotary member; a heating member configured to heat the rotary member, the heating member being held in contact with the rotary member; a temperature detecting element configured to detect temperature of the rotary member or the heating member; a protection element configured to interrupt power supply to the heating member, the protection element being activated when sensing abnormal rise in temperature of the heating member; and a control portion configured to control the image heating apparatus, wherein, when the temperature detected by the temperature detecting element exceeds a threshold value, the control portion stops rotation of the rotary member.

Abstract: An image forming apparatus includes: an image bearer bearing a toner image; a transferer transferring the toner image from the image bearer onto a recording material and including a transfer member forming a transfer nip between itself and the image bearer; and a fixer fixing portion for fixing on the recording material the transferred toner image and including a fixing sleeve, a heater contacting an inner surface of the fixing sleeve, and a pressing roller for forming a fixing nip between itself and the heater through the fixing sleeve. At least one of the fixing sleeve and the pressing roller is grounded through a first series circuit consisting of a rectifying element and a first resistance element and is grounded through a second series circuit, which is connected to the first series circuit in parallel, consisting of a capacitive element and a second resistance element.

Abstract: An image forming apparatus includes an image bearing member for bearing a toner image; a transfer portion for transferring the toner image from the image bearing member onto a recording material, the transfer portion including a transfer member for forming a transfer nip between itself and the image bearing member; and a fixing portion for fixing on the recording material the toner image transferred on the recording material, the fixing device including a fixing sleeve, a heater contacted to an inner surface of the fixing sleeve, and a pressing roller for forming a fixing nip between itself and the heater through the fixing sleeve. At least one of the fixing sleeve and the pressing roller is grounded through a first series circuit consisting of a rectifying element and a first resistance element and is grounded through a second series circuit, which is connected to the first series circuit in parallel, consisting of a capacitative element and a second resistance element.