| 摘要 |
The encoder includes a scale having a first periodic pattern and a second periodic pattern, a sensor relatively movable with the scale. The sensor outputs in a first detection state a first periodic signal changing with a change period corresponding to the first periodic pattern and outputs in a second detection state a second periodic signal changing with a longer change period corresponding to the second periodic pattern than that of the first periodic signal. A processor calculates a position in a relative movement direction of the scale and sensor by using both the first and second periodic signals. The processor takes in the second periodic signal, the first periodic signal and the second periodic signal in this order at mutually different times, calculates phases of the second, first and second periodic signals at a specific time and calculates the position at the specific time by using the calculated phases. |
