CAPACITIVE VOLTAGE DIVIDER

• US 3,593,115 A
• Filed: 09/10/1969
• Issued: 07/13/1971
• Est. Priority Date: 06/30/1969
• Status: Expired due to Term

• Current Assignee: Dym Herbert, Robert V. Mazza
• Original Assignee: Dym Herbert, Robert V. Mazza
• Inventors: DYM HERBERT, Mazza, Robert V.
• Application Number:
  US04/856,745
• Time in Patent Office: 671 Days
• US Class Current: 340/870.35
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06G 7/30 for interpolation or extrapolation G06G7/122 takes precedence
• CPC Class Codes: G06G 7/46 using discontinuous medium, e.g. resistance network

Abstract

A capacitive voltage divider arrangement for driving a position transducer. Individual ones of a first plurality of individual capacitor plates are respectively capacitively coupled to individual ones of a second like plurality of capacitance plate areas, the second plurality of capacitive areas being conductively connected together and varying in area from plate area to plate area. Individual ones of a third plurality of capacitance plate areas, which are conductively connected together, are likewise respectively capacitively coupled to individual ones of the first plurality of plates. The voltage distribution on a plurality of position sensing grid lines, individual ones of which are connected to respective individual ones of the first plurality of plates, varies in accordance with the varying in areas from plate area to plate area of the second plurality of plate areas.

Claims

1. A capacitive voltage divider comprising:

a plurality of individual capacitor plate means; and

plate means coupled to an alternating voltage source and capacitively coupled to each of said plurality of individual capacitor plate means with the area of said plate means capacitively coupled to each of said individual capacitor plate means varying from individual capacitor plate means to individual capacitor plate means over said plurality of individual capacitor plate means so that the capacitance frOm individual capacitor plate means to individual capacitor plate means varies according to the said varying of said area; and

means for coupling a further capacitance between each plate means and said alternating voltage source so that the potential at individual ones of said plurality of individual capacitor plate means varies in accordance with the manner in which said capacitance varies.

2. The capacitive voltage divider as set forth in claim 1 wherein said plate means comprises an integral conductive plate with the said area of said plate capacitively coupled to each of said capacitor plate means varying from individual plate to individual plate over said plurality of individual capacitor plate means as a function of the geometric configuration of said plate.

3. The capacitive voltage divider as set forth in claim 2 wherein said means for coupling a further capacitance comprises a plurality of capacitances corresponding in number to the said plurality of individual capacitor plate means wherein said plurality of capacitances are coupled to respective ones of said individual capacitor plate means and wherein a plurality of voltage tap means are respectively coupled to a point between each of said plurality of individual capacitor plate means and said like plurality of capacitances so that the voltage from tap to tap varies according to the said geometric configuration of said plate.

4. The voltage divider as set forth in claim 3 wherein said like plurality of capacitances vary from capacitance to capacitance inversely as the said capacitance from individual plate to individual plate varies.

5. The voltage divider as set forth in claim 4 wherein said like plurality of capacitances comprises a corresponding second plurality of individual capacitor plate means each capacitively coupled to an integral conductive plate which has a geometric configuration which is the complement of the said geometric configuration.

6. The voltage divider as set forth in claim 5 wherein said first recited plurality of individual capacitor plate means and said corresponding second plurality of individual capacitor plate means are respectively in integral form.

7. A voltage divider device comprising:

a first plurality of capacitive plate areas conductively coupled together and varying in area from plate area to plate area;

a second plurality of capacitive plates individual ones of which are capacitively coupled to respective individual ones of said first plurality of plate areas so that the capacitance between respective ones of said first plurality of plate areas and said second plurality of plates varies in accordance with the said varying area; and

a plurality of capacitance means individual ones of which are respectively coupled to individual ones of said second plurality of capacitive plates so that an alternating voltage potential applied between said plurality of capacitance means and said first plurality of capacitive plate areas is respectively divided in accordance with the capacitance of individual ones of said plurality of capacitance means and the capacitance between corresponding respective ones of said first plurality of plate areas and said second plurality of plates.

8. The voltage divider device as set forth in claim 7 wherein said plurality of capacitance means comprises a third plurality of capacitance plates individual ones of which are conductively coupled to respective individual ones of said second plurality of capacitive plates and a fourth plurality of capacitive plate areas conductively coupled together with individual ones of said capacitive plate areas capacitively coupled to respective individual ones of said third plurality of capacitance plates.

9. The voltage divider device as set forth in claim 8 wherein individual ones of said third plurality of capacitance plates are integral with respective individual ones of said second plurality of capacitive plates and said fourth plurality of capacitance plates vary in area from plate area to plate area as the complement of the said varying in area from plate area to plate area of said first plurality of capacitive plates.

10. The voltage divider device as set forth in claim 8 wherein said first plurality of capacitive plate areas are in integral form so as to comprise a first single plate, wherein individual ones of said third plurality of capacitance plates are integral with corresponding respective individual ones of said second plurality of capacitance plates and wherein said fourth plurality of capacitance plates are in integral form so as to comprise a second single plate.

11. The voltage divider device as set forth in claim 10 wherein said first single plate in uniformly conductive and varies geometrically thereby providing the said varying in area.

12. The voltage divider device as set forth in claim 11 wherein said second plate is uniformly conductive and varies geometrically as the complement of said first plate.

13. The voltage divider d5vice as set forth in claim 12 wherein said first and second plates are triangular in shape.

14. A voltage divider for a position transducer comprising:

first drive plate means having a plurality of conductive plate segments with said plate segments conductively coupled together and varying in area from plate segment to plate segment;

a plurality of individual coupling plates individual ones of which are capacitively coupled to respective individual ones of said plurality of plate segments so that the respective capacitances between individual ones of said plurality of individual coupling plates and the corresponding individual ones of said plurality of plate segments vary in accordance with the said varying in area;

a plurality of position sensing grid lines with individual ones of said plurality of grid lines connected respectively to individual ones of said plurality of individual coupling plates; and

means coupling a varying voltage between said drive plate means and respective ones of said individual coupling plates so that said varying voltage is divided at said grid lines in accordance with said respective capacitances.

15. The voltage divider as set forth in claim 14 wherein each of said plurality of position sensing grid lines is integral with the corresponding one of said plurality of individual coupling plates to which it is connected.

16. The voltage divider as set forth in claim 14 wherein said first drive plate means comprise a first conductive drive plate having a predetermined geometric configuration so that said plurality of plate segments vary in area from plate segment to plate segment according to said predetermined geometric configuration.

17. The voltage divider as set forth in claim 16 wherein said configuration is triangular.

18. The voltage divider as set forth in claim 16 wherein individual ones of said plurality of individual coupling plates are further capacitively coupled to respective individual ones of the plurality of plate segments of a second conductive drive plate means wherein said varying voltage is thereby coupled to respective individual ones of said plurality of individual coupling plates through said second conductive drive plate.

19. The voltage divider as set forth in claim 18 wherein the respective said plate segments of said first conductive drive plate means linearly vary in area from plate segment to plate segment and the respective sums of the areas of individual ones of said plurality of segments of said first conductive drive plate means and corresponding individual ones of said plurality of segments of said second conductive drive plate means, wherein corresponding individual ones are capacitively coupled to respective individual ones of said plurality of individual coupling plates, are constant over said plurality of individual coupling plates.

20. The voltage divider as set forth in claim 19 wherein the said first and second conductive drive plates are triangular.

21. A vOltage divider position transducer with capacitive transducer driving means, said transducer driving means including X-direction drive means comprising a first plurality of capacitive coupling plate means conductively coupled together and varying in area from coupling plate means to coupling plate means and a first plurality of individual coupling plates capacitively coupled to respective individual ones of said plurality of capacitive coupling plate means so that the capacitance between respective individual ones of said first plurality of individual coupling plates and the corresponding individual ones of said first plurality of coupling plate means varies in accordance with the said varying in area from coupling plate means to coupling plate means so as to thereby form a first plurality of capacitance varying in value from capacitance to capacitance and means coupling a varying voltage between said first plurality of capacitive coupling plate means and respective ones of said first plurality of individual coupling plates so that said varying voltage is divided at said individual coupling plates in accordance with said capacitance whereby variations in divided voltage are indicative of position.

22. The position transducer as set forth in claim 21 wherein individual ones of a plurality of X-direction position sensing grid lines means for said position transducer are respectively coupled at one end to individual ones of said first plurality of individual coupling plates of said X-direction drive means.

23. The position transducer as set forth in claim 22 wherein said transducer driving means further includes a second X-direction drive means similar to the first recited X-direction drive means wherein individual ones of the first plurality of individual coupling plates of said second X-direction drive means are arranged similar to the said first plurality of individual coupling plates of said first recited X-direction drive means and are respectively coupled to the opposite ends of individual ones of said plurality of grid lines.

24. The position transducer as set forth in claim 22 wherein the said means coupling a varying voltage of said X-direction drive means includes a second plurality of capacitive coupling plate means conductively coupled together and varying in area from coupling plate means to coupling plate means and a second plurality of individual coupling plates individual ones of which are both conductively coupled to respective individual ones of said first plurality of individual coupling plates and capacitively coupled to respective individual ones of said second plurality of capacitive coupling plate means so that the capacitance between respective individual ones of said second plurality of coupling plates and individual ones of said second plurality of coupling plate means varies in accordance with the said varying in area from coupling plate means to coupling plate means of said second plurality of capacitive coupling plate means whereby a second plurality of varying capacitance respectively coupled to said first plurality of varying capacitance is provided.

25. The position transducer as set forth in claim 24 wherein the said varying in area from coupling plate means to coupling plate means of said first plurality of capacitive coupling plate means is linear so that said first plurality of capacitance varies linearly from capacitance to capacitance.

26. The position transducer as set forth in claim 25 wherein the said varying in area from coupling plate means to coupling plate means of said second plurality of capacitive coupling plate means is linear and the respective sums of the areas of individual ones of said first plurality of capacitive coupling plate means and the corresponding individual ones of said second plurality of capacitive coupling plate means are constant from sum to sum so that the respective sums of individual ones of said first plurality of varying capacitance and the corresponding individual oneS of said second plurality of varying capacitance respectively coupled thereto are constant from sum to sum.

27. The position transducer as set forth in claim 26 wherein the said first plurality of capacitive coupling plate means and the said second plurality of capacitive coupling plate means each comprise a triangular conductive plate to form a complementary pair of drive plates, one being the complement of the other such that the said sums of said area and the said sums of said capacitance are constant in accordance therewith.

28. The position transducer as set forth in claim 27 wherein each of the plates of said second plurality of individual coupling plates are respectively integral with the corresponding ones of said first plurality of individual coupling plates thereby forming a plurality of individual integral coupling plates to be shared by each of the triangular conductive plates comprising said first and second plurality of capacitance coupling plate means.

29. The position transducer as set forth in claim 29 wherein said driving means further includes Y-direction drive means the same as the recited X-direction drive means and wherein individual ones of a plurality of Y-direction position sensing grid line means for said position transducer are respectively coupled at one end to individual ones of the plurality of individual integral coupling plates of said Y-direction drive means.

30. The position transducer as set forth in claim 29 wherein said driving means includes a second X-direction drive means and a second Y-direction drive means respectively the same as the recited X-direction drive means and Y-direction drive means with individual ones of their respective plurality of individual integral coupling plates respectively coupled to the opposite ends of individual ones of the respective plurality of X-direction grid lines and Y-direction grid lines.

31. The position transducer as set forth in claim 29 wherein said driving means further includes means for alternately energizing one of said X-direction and Y-direction drive means with said varying voltage so that during a first time interval one of the triangular conductive plates of said complementary pair of drive plates is energized to provide a voltage distribution on the position sensing grid lines corresponding thereto as a linear function of position and during a second time interval both of the triangular conductive plates of said complementary pair of drive plates are energized to provide a voltage distribution on said grid lines which is constant with position.

32. A capacitive voltage divider for a position transducer comprising:

first and second conductive plates;

a plurality of capacitance plates each coupled to both said first and second conductive plates so that the area of respective individual ones of said plurality of plates capacitively coupled to one of said first and second conductive plates varies over said plurality from one to another and so that each of the sums of the capacitance area of said first and second conductive plates capacitively coupled to the respective plates of said plurality of capacitance plate is equal;

a plurality of position sensing grid lines with individual ones of said plurality of grid lines coupled respectively to individual ones of said plurality of capacitance plates; and

control circuit means including means for energizing said first conductive plate with an alternating voltage when said second conductive plate is at a fixed potential so that the respective output voltages on said plurality of grid lines varies as a function of the geometric configuration of said first plate.

33. The capacitive voltage divider as set forth in claim 32 wherein the respective areas of said first conductive plate capacitively coupled to respective ones of said plurality of capacitance plates vary linearly in size from area to area.

34. The capacitive voltage divider as set forth in claim 33 wherein Said control circuit means further include means for energizing said second conductive plate so that the respective output voltages on said plurality of grid lines is constant from grid line to grid line.