According to one embodiment, a temperature control apparatus supplies power to a heater to control temperature of a temperature control target. The temperature control apparatus includes a temperature estimation unit to estimate a temperature of a temperature control target based on electrical power supplied to the heater. The temperature control apparatus also includes control signal generation unit that calculates a duty value for the heater based on an estimated temperature from the temperature estimation unit, a detected temperature from a temperature sensor, and a target temperature for the temperature control target. A pulse signal for controlling the electrical power supplied to the heater is generated based on the calculated duty value.

An electric circuit includes a power supply circuit that supplies electric power, a load, a power supply line that supplies the power from the power supply circuit to the load, a signal line located along and adjacent to the power supply line, a detector that detects whether the power is being supplied to the signal line, and a controller including a processor, and configured to, when the processor executes a control program, cause the power supply circuit to supply the power to the power supply line, in a case where the detector detects the power supply to the signal line when a signal is outputted to the signal line, and restrict the power supply circuit from supplying the power to the power supply line, in a case where the detector does not detect the power supply to the signal line.

A sensor apparatus includes a photosensitive sensor, a cover, and a moving mechanism. The photosensitive sensor includes a first lens and a second lens which focus on a photosensitive element. The cover includes a first slit arranged on an optical axis of the first lens and a second slit arranged on an optical axis of the second lens. The moving mechanism is configured to move the photosensitive sensor and the cover relative to each other so that the second slit is arranged on the optical axis of the first lens.

A fixing unit includes a film including a tubular shape and configured to rotate, a heater arranged inside the film and including a heating resistor configured to generate heat by passing alternating current therethrough and an insulator configured to cover the heating resistor, a sliding member arranged between the heater and the film and configured to be in sliding contact with an inner surface of the film, the sliding member having electric conductivity, a pressing member configured to be in pressure contact with the sliding member across the film to form a nip portion between the sliding member and the pressing member, and a conductive member electrically connected to a ground potential via at least one impedance element. The sliding member is electrically connected to the conductive member.

An image-forming apparatus includes a rotatable developer-bearing member to bear a developer composed of a toner particle and a transfer promoting particle attached to the toner particle. When F denotes pressing force for pressing the developer-bearing member against an image-bearing member, and N denotes a total number of the transfer promoting particles interposed between the toner particle and the image-bearing member, adhesion strength Ft between the transfer promoting particle and the toner particle measured by pressing the transfer promoting particle against the toner particle at a pressing force per unit transfer promoting particle F/N and adhesion strength Fdr between the transfer promoting particle and the image-bearing member measured by pressing the transfer promoting particle against the image-bearing member at the pressing force per unit transfer promoting particle F/N, satisfy Ft<Fdr. Electrical discharge is generated upstream of a transfer portion in a movement direction of an intermediate transfer belt.

In a longitudinal direction of a heater, a distance from a center portion of the heater to a first temperature detection element is a first distance, and a distance from the center portion of the heater to a second temperature detection element is a second distance greater than the first distance. In a first area which is farther from the center portion of the heater than the second temperature detection element is from the center portion of the heater in the longitudinal direction of the heater, a distance between a first conductor and a second conductor in a transverse direction of the heater is a first inter-conductor distance and a distance between a third conductor and a fourth conductor in the transverse direction is a second inter-conductor distance longer than the first inter-conductor distance.

A fixing unit includes a first heater, a first switch, a second heater, and a second switch. In an image forming mode, a controller controls the first switch and the second switch to keep a temperature of the fixing unit at a fixing temperature serving as a target temperature for fixing the image on the sheet. In a standby mode, the controller controls the first and second switches to keep the temperature of the fixing unit at a standby temperature, and controls the first and second switches such that a period in which a first current is supplied to the first heater and a period in which a second current is supplied to the second heater do not overlap.

A controller obtains a first duty cycle of a first current to be supplied to a first heater and a second duty cycle of a second current to be supplied to a second heater and controls the first switch and the second switch after the reduction control period, such that the temperature of a fixing unit maintains a target temperature for fixing the image by the fixing unit.

In a caser where a first current is supplied to a first heater, a controller gradually increases the first current in a first period, supplies the first current based on a first duty cycle in a second period, and gradually reduces the first current to stop supplying the first current in a third period. In a case where a second current is supplied to a second heater, the controller gradually increases the second current in a fourth period, supply the second current based on a second duty cycle in a fifth period, and gradually reduces the second current to stop supplying the second current in a sixth period. The controller controls the supply of the second current such that part of the fourth period overlaps with the third period.

A heater control device includes a triac connected in series between an alternating-current power supply and a heater, the triac including a first main electrode, a second main electrode, and a gate electrode; a phototriac coupler configured to transmit a heater trigger signal to the gate electrode of the triac; a first resistor and a second resistor each of which is connected in series to the phototriac coupler and configured to limit current in accordance with a phase control enable signal indicative of a period of phase control; and a resistor selection circuit configured to select one of the first resistor and the second resistor and connect the selected resistor to the second main electrode of the triac. The first resistor and the second resistor have different rated powers and different breakabilities from each other.