| 摘要 |
1, 243, 121. Sensing position electrically. NATIONAL CASH REGISTER CO. Aug. 14, 1969 [Aug. 29, 1968], No.40653/69. Heading GIN. The relative positions of two members, one of which has a coil 17 mounted thereon and the other 15 of which is "lossy", is determined by means responsive to both the change of inductance and Q of the coil due to relative movement of the two members. As shown, in a paper punch, a solenoid 18 is energized to operate the punch 11 via a "lossy" armature 15 which may be either of magnetic material or magnetic with a metallic, non-magnetic portion adjacent the coil so that a large amount of energy is absorbed from the coil due to eddy current losses and/or hysteresis losses. In one embodiment, Fig. 4 (not shown), the coil forms part of a resonant circuit and is energized at or near the resonant frequency by squarewave pulses. The resonant circuit is connected to a level detector which gives an indication when the armature reaches the extreme remote position from the coil by sensing the signal representative of the inductance and Q changes in the coil. In this manner very small displacements may be determined. The velocity and acceleration of the armature may also be determined. In an alternative, Fig. 6 (not shown), the coil is connected in an A. C. bridge circuit and is energized by a sinusoidal voltage. When the armature moves away from the coil, the bridge is driven towards balance, the inductance change in the coil producing reactive balancing and the Q change producing resistive balancing of the bridge. |
