Toroidal electrolytic angle transducer

• US 3,946,494 A
• Filed: 09/30/1974
• Issued: 03/30/1976
• Est. Priority Date: 09/30/1974
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Company (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Wells, Perry L.
• Primary Examiner(s): Aegerter, Richard E.
• Assistant Examiner(s): Phillips, Charles E.
• Application Number:
  US05/510,662
• Time in Patent Office: 547 Days
• Field of Search: 33/366, 338/43, 338/44, 338/80, 338/81, 73/516 R, 73/516 LM, 73/517 R, 324/65 R
• US Class Current: 33/366.22
• CPC Class Codes: G01C 9/06 Electric or photoelectric indication or reading means
• CPC Class Codes: G01C 9/20 the indication being based on the inclination of the surface of a liquid relative to its container

Abstract

A toroidal electrolyte-type angular transducer is provided for measuring angular displacement or tilt from a vertical plane. Three conducting paths in the electrolyte are established between two measuring electrodes and an auxilliary electrode respectively and a common electrode. Angular displacement is simply related to the values of the conductances in the various paths. In a preferred embodiment of the invention several guard-ring electrodes are included to divert spurious leakage currents from the common electrode so that the leakage current will not affect the measurement. The guard-ring electrodes are maintained at the same potential appearing at the collector electrode to ensure that no leakage currents pass between the two. Another preferred embodiment the invention provides that the two measuring electrodes are driven by voltages equal in magnitude and opposite in sign. A high gain operational amplifier is interconnected between the auxiliary electrode and the common electrode. By means of this arrangement a single voltage reading may be obtained which is directly proportional to angular displacement.

Claims

1. A toroidal electrolyte-type angle transducer comprising:

a first housing element;

a second housing element mounted with an inner surface in opposition to an inner surface of said first housing element to form a cavity therebetween;

an electrolyte contained in a portion of said cavity;

a plurality of conducting electrodes on the inner surface of said first housing element;

a common electrode on the inner surface of said second housing element in electrical contact with said plurality of conducting electrodes through said electrolyte;

at least one guard-ring electrode on the inner surface of said second housing element and spaced apart and substantially coextensive with from said common electrode to provide electrical isolation between said at least one guard-ring electrode and said common electrode; and

equalization circuit means for driving said at least one guard-ring electrode at the same electrical potential as the potential of said common electrode to prevent the flow of current therebetween.

2. A transducer as in claim 1 wherein said common electrode is of a substantially circular shape and said at least one guard-ring electrode comprises a first electrode positioned radially outward from said common electrode and a second electrode positioned radially inward from said common electrode.

3. A transducer as in claim 1 wherein said equalization circuit means comprises a high impedance amplifier of gain substantially equal to unity interconnected between said common electrode and said at least one guardring electrode.

4. A toroidal electrolyte-type angle transducer as in claim 1 wherein said plurality of conducting electrodes comprises a first measuring electrode, a second measuring electrode, and an auxiliary electrode;

said transducer further comprising;

first circuit means for driving said first and second measuring electrodes with electrical potentials which are substantially equal in magnitude and opposite in phase; and

second circuit means for driving said auxiliary electrode to produce a virtual ground at said common electrode.

5. A transducer as in claim 4 wherein said second circuit means comprises a high gain amplifier electrically interconnected between said auxiliary electrode and said common electrode.

6. A transducer as in claim 5 wherein said first circuit means includes an inverting amplifier of substantially unit gain interconnected between said first and second measuring electrodes for providing a driving potential on said second measuring electrode which is equal in magnitude and opposite in phase to the driving potential on said first measuring electrode.

7. A transducer as in claim 6 wherein said equalization circuit means comprises a high impedance amplifier of gain substantially equal to unity interconnected between said common electrode and said at least one guard-ring electrode.