| 摘要 |
A switch operating collar encircles a shaft and includes two semi-cylindrical metal members interconnected with abutting end faces by suitable set screws for releasably clamping the collar to the shaft. A circumferentially extended slot or keyway is machined or otherwise formed in the outer peripheral surface of the one member. The side edges of the slot are formed along a chordal line to define relatively sharp discontinuities in the face or periphery of the collar. The collar screws are accessible from the semi-circular member containing the slot. Shaft bearings firmly support the signal drive shaft and clamped collar unit, or units, for rotation about a predetermined axis. A metal proximity sensor head is mounted aligned with the peripheral surface of the collar. The circumferential extent of the slot is slightly larger than the operative corresponding dimension of the sensor head. The axial width of the collar unit is slightly less than the sensor head such that the screw holes do not generate operative output signals. Each movement of the slot past the sensing head generates a pulse signal having an inclined leading and trailing edge. A threshold detector responds at a selected level to produce a square wave output signal for providing digital logic signals.
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