An image forming apparatus includes a power controller that starts an examination mode by an external operation. The examination mode detects a temperature-resistance property of a resistive heat generator. The power controller supplies power at a predetermined power duty cycle to the resistive heat generator. The power controller obtains the power supplied to the resistive heat generator and a change in a temperature of the resistive heat generator, that is detected by a temperature detector, while the power controller supplies the power at the predetermined power duty cycle to the resistive heat generator. The power controller calculates the temperature-resistance property of the resistive heat generator based on the power and the change in the temperature that are obtained. The power controller adjusts a power duty cycle at which the power is supplied to the resistive heat generator based on the temperature-resistance property.

The power supply apparatus includes a switching element connected to a primary winding of a transformer to which an input voltage is applied; a feedback unit configured to output a first feedback voltage according to an output voltage, the output voltage induced in a secondary winding of the transformer and output to a load; a current detection unit for detecting a current flowing to the switching element and output a second feedback voltage according to the current detected; a limiting unit for limiting the first feedback voltage so that the current flowing to the switching element is below a predetermined current value; an output unit for outputting a driving signal for the switching element based on the first feedback voltage limited by the limiting unit and on the second feedback voltage; and a control unit for controlling the switching element according to the driving signal output from the output unit.

A control portion determines the lengths of time required to raise a plurality of heat generating elements to prescribed start-up completion target temperatures, and when a heat generating element determined to have the longest start-up requirement time among a plurality of heat generating elements is a second heat generating element, and a heat generating element determined to have shorter start-up requirement time than that of the second heat generating element among a plurality of heat generating elements is a first heat generating element, the control portion controls power to be supplied to the first heat generating element by changing a start-up control parameter for the first heat generating element with reference to the start-up performance of the second heat generating element.

The power supply apparatus includes a switching element connected to a primary winding of a transformer to which an input voltage is applied; a feedback unit configured to output a first feedback voltage according to an output voltage, the output voltage induced in a secondary winding of the transformer and output to a load; a current detection unit for detecting a current flowing to the switching element and output a second feedback voltage according to the current detected; a limiting unit for limiting the first feedback voltage so that the current flowing to the switching element is below a predetermined current value; an output unit for outputting a driving signal for the switching element based on the first feedback voltage limited by the limiting unit and on the second feedback voltage; and a control unit for controlling the switching element according to the driving signal output from the output unit.

An image forming apparatus includes a first frame member and a second frame member which are aligned in a direction of a rotation axis of an image bearing member and faces each other across an image forming unit and a stacking unit. The first frame member includes a first portion including a first side surface facing the image forming unit and a second portion, which is fixed to the first portion, including a second side surface facing the stacking unit. The second frame member includes a third side surface facing the image forming unit and the stacking unit, and at least a part of the second side surface is provided in a position different from a position of the first side surface in the direction of the rotation axis of the image bearing member.

An image forming apparatus includes a first frame member and a second frame member which are aligned in a direction of a rotation axis of an image bearing member and faces each other across an image forming unit and a stacking unit. The first frame member includes a first portion including a first side surface facing the image forming unit and a second portion, which is fixed to the first portion, including a second side surface facing the stacking unit. The second frame member includes a third side surface facing the image forming unit and the stacking unit, and at least a part of the second side surface is provided in a position different from a position of the first side surface in the direction of the rotation axis of the image bearing member.

An image forming apparatus includes a fixing portion, a temperature detection portion, a power supply portion, a control portion, a photovoltaic module and a power storage/supply portion which stores power from the photovoltaic module and which performs power supply to the temperature detection portion when power supply from the power supply portion to the temperature detection portion is stopped. The control portion detects, when a return condition is satisfied, the temperature of the fixing portion based on the output of the temperature detection portion, and as a temperature on return is higher, the control portion starts fixing return processing at later timing whereas as the temperature on return is lower, the control portion starts the fixing return processing at earlier timing.

A power control apparatus includes a power detection circuit to detect DC power converted from AC power supplied from a power supply and to be supplied to a control board of an image forming apparatus. The power control apparatus includes circuitry configured to, in response to a first printing operation performed by the image forming apparatus, calculate fluctuations in the DC power in each preset control period from a start of the first printing operation until stabilization of the DC power. The power control apparatus includes, in response to a printing operation subsequent to the first printing operation performed by the image forming apparatus, determine allocation of the AC power to a fixing device of the image forming apparatus in a next preset control period based on power obtained by adding, to the DC power, an average of the fluctuations in a plurality of preset control periods.

A power supply apparatus generates an output voltage. A boost circuit boosts a voltage supplied from a reference voltage source and generates a first power supply voltage. A processor controls switching the boost circuit on and off. A first transistor is connected to the first power supply voltage. A second transistor is connected to a collector of the first transistor. A resistance element is connected to a collector of the second transistor. A voltage source is connected to the resistance element and generates a second power supply voltage. A collector voltage, which is an output voltage, of the second transistor is controlled by controlling an amount of base current of the first transistor.

An image forming system includes an image forming apparatus including an AC-DC converter and a main board, and a sub board having a sub connector connectable with a main connector of the main board. When the sub board is not connected with the main board, a main DC-DC converter on the main board converts a DC voltage from the AC-DC converter into a first DC voltage and output the first DC voltage to a circuit element for image formation. When the sub board is connected with the main board, the AC-DC converter outputs the DC voltage to a sub DC-DC converter on the sub board via the main connector and the sub connector, and the sub DC-DC converter converts the DC voltage from the AC-DC converter into a second DC voltage and output the second DC voltage to the circuit element via the sub connector and the main connector.