Abstract: A signal generation portion of an image forming apparatus generates a different level of signal according to an output value of a pyroelectric sensor. A recognition portion determines a measurement value on the speed of change of the signal and recognizes which of a first range and a second range the measurement value is. In a power supply portion, when the measurement value falls within the first range in a mode other than a power-saving mode, and the image forming apparatus is brought into the power-saving mode, and, when the measurement value falls within the second range in the power-saving mode, the power-saving mode is cancelled.

Abstract: In an image forming apparatus, a first detection portion includes a pyroelectric sensor and detects the upper half of the human body. A first signal generation portion generates a first signal whose level varies according to the output value of the pyroelectric sensor. A second detection portion includes a pyroelectric sensor and detects a lower area than the first detection portion. A second signal generation portion generates a second signal whose level varies according to the output value of the pyroelectric sensor. A storage portion stores discrimination data including data defining, with respect to the waveforms of the first and second signals, a condition for recognizing a human moving toward the image forming apparatus and a condition for recognizing a human crossing a detection area of the pyroelectric sensors. A recognition portion recognizes the direction of movement of a human.