| 摘要 |
PURPOSE:To reduce the size of an absolute encoder and to improve its accuracy by arranging a magnetism detector in X and Y coils and detecting phase differences between currents which flow through those two couples of coils and a voltage developed at the magnetic detector. CONSTITUTION:The currents which flow through the Y coils 16-1 and 16-2 are inputted to the start pulse generator 36 of a phase detection part 31 to generate a start pulse. The AC output voltage V1 of the magnetic field detector 14, on the other hand, is inputted to a zero-cross clock pulse generator 33 to generate a reset pulse. A counter 34 starts counting clock pulses from a clock generator 37 with the start pulse from the generator 36 and finishes the counting with the reset pulse from the generator 33. Consequently, the values of the counter 34 corresponding to the angle of rotation of a shaft 13 which is found has its error corrected by an error correcting circuit 38 and is outputted through an angle output circuit 39. Further, an sin/cos oscillator 35 supply its sine output and cos output to the X coils 15-1 and 15-2 and Y coil 16-1 and 16-2 respectively.
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