| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an encoder capable of suppressing the erroneous detection of an origin signal.SOLUTION: An encoder includes: a scale formed with a pattern for origin detection; an origin detection part for reading the pattern for origin detection; a processing part for outputting the origin signal. The origin detection part includes a plurality of detection element groups each having at least a first detection part, a second detection part, a third detection part and a fourth detection part, and the first and second detection parts and the third and fourth detection parts are each arranged symmetrically to the center of the detection element group. The pattern for origin detection is characterized such that the length of a detecting direction of physical characteristics different from an origin peripheral part detected by the origin detection part is shorter than the length of a detecting direction of the detection element group. The origin detection part outputs a first signal based on the first and third detection parts and a second signal based on the second and fourth detection parts, and the processing part outputs a fifth signal based on a third signal based on the first signal and a first threshold and a fourth signal based on the second signal and a second threshold as an origin signal.</p> |
