Patent ID: 7357041

Claim:
A rotation detection device comprising: a rotation detecting means that detects rotary motion of a rotating body; a rotation angle converter that outputs an rotation angle of the rotating body based on an output of the rotation detecting means; an angular velocity converter that outputs an angular velocity of the rotating body based on the output of the rotation detecting means; a rotation calculating means including: a rotation angle linear function calculator that calculates a linear function concerning an output of the rotation angle converter and has a phase adjustor for setting an adjustable constant term of the linear function; a trigonometric function calculator that calculates a sine or a cosine of an output value of the rotation angle linear function calculator; an amplitude adjustor that multiplies an output value of the trigonometric function calculator by a predetermined gain; and a multiplier that multiplies an output of the amplitude adjustor by the output of the angular velocity converter; and an automatic phase adjusting means including: a phase shifting means that differentiates or integrates, with respect to time, an output of the angular velocity converter; a shifted phase sampling means that samples an output value of the phase shifting means at predetermined intervals associated with the output value of the rotation angle linear function calculator; a periodic phase deviation integrating means that adds an output of the shifted phase sampling means to a summation of outputs, having been obtained in one cycle before a predetermined point of time, of the shifted phase sampling means at the predetermined intervals associated with the output value of the rotation angle linear function calculator; and a phase gain multiplying means that multiplies a calculation result of the periodic phase deviation integrating means by a predetermined gain, wherein the periodic phase deviation integrating means is configured to output an output of the phase gain multiplying means as a phase adjusting value for the phase adjustor.