| 摘要 |
PROBLEM TO BE SOLVED: To provide an electromagnetic induction type encoder which obtains high signal intensity by reducing offset by a short scale coil, is resistant to fluctuations in the yaw direction, is high precision, and is inexpensive. SOLUTION: The electromagnetic induction type encoder includes a large number of scale coils 14 arranged on a scale 10 in the measurement direction and a transmitting coil 24 and a receiving coil 20 which are placed on a grid 12 so that they move relatively in the measurement direction with respect to the scale, and detects the relative amount of movement of the scale and the grid from a change in magnetic flux detected by the receiving coil through the scale coils when the transmitting coil is energized. The transmitting coils, the receiving coils, and the scale coils are placed with a plurality of sets (24A, 24B), (20A, 20B), (14A, 14B) symmetrically with respect to the center of the scale. One of the scale coils arranged symmetrically with respect to the scale center is displaced by half the phase of the scale pitch with respect to the other scale coil. COPYRIGHT: (C)2009,JPO&INPIT
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