A control device includes an AC-DC converter that converts power supplied from a commercial power source into DC, a DC-DC converter that supplies the DC to a fixing heater, an calculator that calculates a target DC voltage of the DC to be supplied to the fixing heater, based on detected temperature of the fixing heater, an overcurrent detection unit that outputs an interruption signal when an overcurrent detection value is detected in a circuit including a switching element, and a controller that calculates switching time for switching the switching element so that an output of the DC-DC converter reaches the target DC voltage. When the interruption signal is output causing stopping of the switching of the switching element, the controller causes the calculator not to calculate the switching time to continuously use the previously calculated switching time after resuming switching of the switching element at a next switching cycle.

A thermal printhead includes a plurality of heating resistor portions, a first capacitor, a switch section, and a first resistor. The heating resistor portions are electrically connected in parallel to each other. The first capacitor is electrically connected in parallel to the heating resistor portions. The switch section is electrically connected in series to the first capacitor. The first resistor is electrically connected in parallel to the first capacitor.

Provided is a heater that is excellent in heat equalizing property even when being narrow in a sweep direction. Also provided are a fixing device, an image-forming device, and a heating device each including such a heater. A heater is configured to heat an object to be heated in such a manner that at least one of the object to be heated and the heater is swept with the heater disposed opposite the object to be heated. The heater includes a base having a rectangular shape and a plurality of heating cells each independently receiving power supply, the heating cells being disposed on the base and arranged in a longitudinal direction of the base. Each of the heating cells includes a plurality of lateral wires extending in substantially parallel with the longitudinal direction of the base and a plurality of oblique wires tilted relative to the lateral wires.

The image forming apparatus including a fixing unit fixing an image on a recording material to the recording material, the fixing unit including a heater including first and second heat generation members controllable independently of the first heat generation member and formed in a region different from a region in which the first heat generation member is formed in a direction orthogonal to a recording material conveyance direction, and a temperature detection element configured to detect a temperature of the region in which the first heat generation member is formed of the heater; and an energization control unit configured to control energization to the first heat generation member depending on the temperature detected by the temperature detection element, in which the image formed on the recording material is fixed to the recording material with heat from the heater.

A cylindrical fixing member for use with a fixing device includes a heat generating layer and an electrode layer contacting the heat generating layer. The electrode layer is smaller in volume resistance value than the heat generating layer. The electrode layer is formed in a helical shape so that a helical axis thereof extends in a direction along a generatrix direction of the fixing member. One end and the other end of the electrode layer are electrically open.

A power regulation circuit including an input from an alternating current (AC) power supply, a load element connected to the AC power supply input, a dummy power resistor connected in parallel with the load element, and a controller to dynamically control power to the load element and to the dummy power resistor in response to a variation in the power consumption of the load element.

An image heating device is provided with a tubular film, and a unit placed inside the film. The unit includes a heater in contact with an inner surface of the film, a supporting member supporting the heater, and a highly thermal conductive member. The highly thermal conductive member placed between the heater and the supporting member and in contact with the heater. The unit is configured such that when the unit is viewed from a side where a surface of the heater is in contact with the film, at least a portion of the highly thermal conductive member is visible without being hidden behind the heater.

A conveyance device to convey a recording medium includes a heater, a first temperature detector, a second temperature detector, and a recording medium detector. The heater heats the recording medium. The first temperature detector and the second temperature detector detect a temperature of the heater. The recording medium detector detects the recording medium. The first temperature detector is disposed at a position farther from a center position of a heating region of the heater than the second temperature detector in a conveyance orthogonal direction. The conveyance orthogonal direction is along a surface of the recording medium and orthogonal to a direction in which the recording medium is conveyed. The recording medium detector is disposed on a side opposite to the first temperature detector with respect to the second temperature detector in the conveyance orthogonal direction.

A controller controls first and second switching elements so that, in both of the waveforms of alternating currents flowing through the first and second heating elements, a first period including both of a phase control waveform in which a current flows in a part of a half cycle of alternately current and a wave-number control waveform in which a current flows or does not flow over a half cycle of alternately current and a second period including only the wave-number control waveform alternately appear in a control cycle; when the first heating element operates in the first/second period, the second heating element operates in the second/first period; and both the waveforms of the alternating currents flowing through the first and second heating elements are electrically symmetric in the positive and negative directions during the control cycle.

Provided is an image forming apparatus including a temperature sensing circuit to which a temperature sensing element is electrically connected, wherein a surface of a heater on a side where the temperature sensing element is provided is in contact with the inner surface of a film, a heating element is provided in a primary side circuit which is electrically connected to a commercial power supply, and the temperature sensing circuit is electrically insulated from both of the primary side circuit and a secondary side circuit which is electrically insulated from the primary side circuit.