| 摘要 |
<p>An encoder capable of detecting the absolute value of the rotational angle, or the like, of an object with high precision through a simple arrangement. In the encoder, the light receiving region of a photodetector and a region to be detected arranged on a scale plate satisfy a relation W/2<D<W, where W is the width of the light receiving region and D is the pitch of the regions to be detected arranged alternately on two lines. According to that relation, at least one of two adjacent regions to be detected exists at a position overlapping the light receiving region at all times. Since respective regions to be detected have different arrangements of a light and shade pattern along a second direction perpendicular to a first direction along which two lines extend, a region to be detected overlapping the light receiving region can be specified based on light intensity profile data along the second direction. Furthermore, the position in the first direction of a region to be detected specified based on the light intensity profile data along the first direction can be specified.</p> |
