| 摘要 |
A tone wheel made by press-forming a magnetic metal plate, has an annular portion and a plurality of fingers which are arranged in comb teeth fashion on an outer peripheral rim of the annular portion, and formed by bending beck the magnetic metal plate through 180 degrees so as to be overlapped as two layers, so that there is a large change in magnetic flux density as the tone wheel rotates past an opposing sensor, thereby increasing the amount of change in the sensor output signal.
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