| 摘要 |
<p>A humidity resistant device (24 and 78) for reading a meter having multiple dial faces and a rotatable meter hand (17-18) and axle (19) including (a) a plate (16) disposed between the dial face and the meter hand; (b) an array of spaced apart excitable electrodes (11-1 through 11-10); (c) a center electrode (12) in the center portion forming a part of a plate capacitor between each excitable electrode and the center electrode, a receiver circuit (24), for sensing current amplitude through each plate capacitor; (d) an A.C. voltage signal source (25) for placing a predetermined voltage signal on one of the excitable electrodes; and, (e) a D.C. reference voltage source (33) connected both to the center electrode (12), a transimpedance amplifier (44), and a guard (21), to maintain the center electrode (12) and guard (21) at essentially the same voltage.</p> |
