Patent ID: 7873487

Claim:
A position detecting device comprising: a resolver that produces a first sine wave signal and a first cosine wave signal varying in accordance with a position of an object when an excitation signal is applied; a sine wave signal amplifier circuit that amplifies the first sine wave signal and produces an amplified first sine wave signal as a second sine wave signal; a cosine wave signal amplifier circuit that amplifies the first cosine wave signal and produces an amplified first cosine wave signal as a second cosine wave signal; and a computer that determines a position of the object in accordance with the second sine wave signal and the second cosine wave signal, wherein the computer is configured to (a) correct the second sine wave signal based on a comparison of a positive amplitude and a negative amplitude of the second sine wave signal to produce a third sine wave signal, (b) correct the second cosine wave signal based on a comparison of a positive amplitude and a negative amplitude of the second cosine wave signal to produce a third cosine wave signal, (c) correct at least one of the third sine wave signal and the third cosine wave signals based on a comparison of an amplitude of the third sine wave signal and an amplitude of the third cosine wave signal to produce a fourth sine wave signal and a fourth cosine wave signal, and (d) determine the position of the object based on the fourth sine wave signal and the fourth cosine wave signal, and wherein the computer is configured to correct the positive amplitude and the negative amplitude of the second sine wave signal differently based on a comparison result indicating that the positive amplitude and the negative amplitude of the second sine wave signal differ from each other so that the third sine wave signal has the same positive amplitude and negative amplitude, and to correct the positive amplitude and the negative amplitude of the second cosine wave signal differently based on a comparison result indicating that the positive amplitude and the negative amplitude of the second cosine wave signal differ from each other so that the third cosine wave signal has the same positive amplitude and negative amplitude.