Abstract: An image forming apparatus which includes a color detection unit that emits a light to a color material and a reference plate on a printing material and detects the reflected light and corrects an amount of the color material upon image forming based on a detection result, comprises: a storage unit that stores, in advance, the detection result of each of the color material and the reference plate detected; and a blot detection unit that estimates the detection result for the reference plate based on a relationship between a stored reference value of each of the color material and the reference plate and the detection result of the color material, and if a difference between the estimated detection result and the detection result of the reference plate is larger than a predetermined value, detects presence of a blot.

Abstract: A power supply apparatus needs to control an output voltage to a target voltage for a short time. A power supply apparatus of the present invention detects voltages output from a piezoelectric transformer. The power supply apparatus also detects peak values in a plurality of detected voltages according to a plurality of frequencies of pulse signals for the piezoelectric transformer, and identifies a frequency corresponding to the highest peak value, and a frequency corresponding to a next peak value next to and on a higher- or lower-frequency side of the frequency corresponding to the highest peak value. Moreover, the power supply apparatus sets an initial frequency used when starting to control the output voltage of the piezoelectric transformer to the target voltage, within a frequency range between the two identified frequencies.

Abstract: Disclosed is an oscillator device that includes an oscillating system having a first oscillator, a second oscillator, a first torsion spring for connecting the first and second oscillators each other, and a second torsion spring being connected to the second oscillator and having a common torsional axis with the first torsion spring; a supporting system for supporting the oscillating system; a driving system for driving the oscillating system so that at least one of the first and second oscillators produces oscillation as can be expressed by an equation that contains a sum of a plurality of time functions; a signal producing system for producing an output signal corresponding to displacement of at least one of the first and second oscillators; and a drive control system for controlling the driving system on the basis of the output signal of the signal producing system so that at least one of amplitude and phase of the time function takes a predetermined value.