A power supply circuit includes a thermoelectric conversion element configured to generate electric power when it is differentially heated, an adjustable current circuit configured to draw a current from the thermoelectric conversion element and resultantly output a constant current over a period of time, a voltage conversion circuit configured to output a voltage based on the current output by the adjustable current circuit, and a control circuit configured to control the adjustable current circuit to change a target value of the constant current output by the adjustable current circuit.

A power supply circuit includes a thermoelectric conversion element configured to generate electric power when it is differentially heated, an adjustable current circuit configured to draw a current from the thermoelectric conversion element and resultantly output a constant current over a period of time, a voltage conversion circuit configured to output a voltage based on the current output by the adjustable current circuit, and a control circuit configured to control the adjustable current circuit to change a target value of the constant current output by the adjustable current circuit.

An image forming apparatus that avoids adverse effects after the next start-up when the snapshot acquisition process is performed in a power saving state. The image forming apparatus executes a first snapshot acquisition process storing save target information for a first device group, and executes a second snapshot acquisition process storing save target information for a second device group.

An image forming apparatus includes a power supply controller that selects either commercial power or a secondary battery as a power supply and a main controller that controls the power supply controller. The main controller includes a power supply availability determination unit that determines whether or not both the commercial power and the secondary battery are available and a power supply selection unit that instructs the power supply controller to select the secondary battery as the power supply during a predetermined secondary battery usage period and instructs the power supply controller to select the commercial power as the power supply at times other than the secondary battery usage period in case both the commercial power and the secondary battery are available.

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.

An electronic device includes a power unit that accommodates a battery; a communication unit that wirelessly communicates with an external device; and a printer unit that prints print data obtained by the communication unit on a recording paper, wherein an outer appearance of the electronic device is a cylindrical shape.

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.

An image forming apparatus includes: a nonvolatile storage device configured to store save target information related to the image forming apparatus as snapshot data in a power supply continuing period from a time of a power-off operation to a time of interruption of power supply; and a control unit configured to reduce a start-up time upon the next power-on operation, and accordingly start up the image forming apparatus fast, wherein the control unit upon the power-off operation being performed in a first working state of the image forming apparatus, executes a first snapshot acquisition process of storing save target information related to a first device group of the image forming apparatus, and upon the power-off operation being performed in a second working state where power consumption is less than the first working state, executes a second snapshot acquisition process of storing save target information related to a second device group.

An electronic apparatus includes a control portion, a signal output circuit, a switching processing portion, and a determination processing portion. The control portion switches on or off power supply from the primary power source in response to detection of an operation on a power switch. The signal output circuit outputs a preset digital signal. The switching processing portion switches a signal level of the digital signal when a power supply state of the control portion is switched. The determination processing portion determines whether or not to execute power supply to the control portion based on the signal level of the digital signal output by the signal output circuit when power supply from an external power source to the primary power source is started.

An electronic apparatus includes a control portion, a signal output circuit, a switching processing portion, and a determination processing portion. The control portion switches on or off power supply from the primary power source in response to detection of an operation on a power switch. The signal output circuit outputs a preset digital signal. The switching processing portion switches a signal level of the digital signal when a power supply state of the control portion is switched. The determination processing portion determines whether or not to execute power supply to the control portion based on the signal level of the digital signal output by the signal output circuit when power supply from an external power source to the primary power source is started.