Patent ID: 6935195

Claim:
A rotational angle detecting apparatus comprising: rotating member; one or more first targets provided on said rotating member; first detecting means, disposed opposite to said first targets, for outputting a detection signal as said rotating member rotates; and second detecting means for outputting a detection signal having a phase different from that of the detection signal of said first detecting means, whereby an absolute rotational angle of said rotating member is detected on the basis of the detection signals outputted by said first detecting means and said second detecting means, comprising: second targets, the number of which is prime to the number of said first targets, provided on said rotating member or other rotating members rotating coaxially with said rotating member; third detecting means, disposed opposite to said second targets, for outputting a detection signal as the rotating member rotates; and fourth detecting means for outputting a detection signal having a phase different from that of the detection signal of said third detecting means; wherein the absolute rotational angle of said rotating member is detected on the basis of the detection signals outputted by said first detecting means, said second detecting means, said third detecting means and said fourth detecting means.