Patent ID: 7340969

Claim:
A rotation detecting apparatus, comprising: a rotation detecting means for detecting a rotation of a rotor; a rotational speed-detecting means for detecting a rotational speed of the rotor; a transfer signal-generating means for generating a digitized transfer signal on the basis of items of transferred information; a pulsed first output waveform synchronized with rotation of the rotor; a pseudo output waveform having a period independent of the period of the rotation of the rotor and having a first property that is different from that of the first output waveform; wherein said output selection means selects the first output waveform when the rotational speed of the rotor is equal to or higher than a switching speed indicating a dividing line of speed between selection of the output waveforms, and said output-selecting means selects the pseudo output waveform when the rotational speed of the rotor is lower than the switching speed, wherein a second property of the output waveform selected is changed on the basis of the transfer signal.