| 摘要 |
PURPOSE:To perform highly accurate detection with a simple device by disposing a second detector having a first coil pattern of annular wave form in proximity to a first detector having an annular slit row. CONSTITUTION:A second detector 1 composed of a printed wiring substrate having a first coil pattern 7 of continued crank form and seocnd, third coil patterns 8,9 of circular form is disposed in proximitg to the lower part of the first detector 3 which is an annular disc composed of conductive material and arrayed with a plurality of slits 10 at a specified spacing, and is fixed to a support base 2. Then, if a.c. signal is supplied to the first or second coil patterns 7, 8 while the first detector 3 is being rotated cooperatively with the rotating body, strond and weak induced electromotive forces are generated in the second of first coil patterns 8, 7 owing to the effect of the slits 10, whereby the rotating speeds are detected. Since the rotating speed detection signals are obtained from the entire outside circumferential region of the first detector 3, the detection of high accuracy may be performed with less detection coils. |
