Position detecting apparatus, and optical apparatus and position detecting method comprising this

A position detecting method that detects a position of an object, comprising:

• a first step of outputting a plurality of position detecting signals which have different phases respectively that change periodically according to a movement of the object;
• a second step of generating a plurality of phase converted signals, from the plurality of position detecting signals, which have different phases respectively by giving predetermined phase differences to the plurality of position detecting signals;
• a third step of obtaining first position data corresponding to a position of the object on the basis of the plurality of position detecting signals;
• a fourth step of obtaining second position data corresponding to a position of the object on the basis of the plurality of phase converted signals generated in the second step;
• and
• a fifth step of obtaining a position of the object on the basis of the first position data and the second position data.

An image reading apparatus comprising:

• an image sensing unit that senses an object image;
• an optical unit adapted to focus the object image;
• a position sensor that outputs a plurality of position detecting signals which have different phases respectively that change periodically according to a movement of the object;
• a phase converting unit that generates a plurality of phase converted signals, from the plurality of position detecting signals, which have different phases respectively by giving each predetermined phase difference to the plurality of position detecting signals;
• a first calculating unit that obtains first position data corresponding to a position of the optical unit on the basis of the plurality of position detecting signals;
• a second calculating unit that obtains second position data corresponding to a position of the optical unit on the basis of the plurality of phase converted signals generated by said phase converting unit;
• and
• a third calculating unit that obtains a position of the optical unit on the basis of the first position data and the second position data,
• wherein the image sensing unit senses the object image in the position obtained by the third calculating unit.