Two-dimensional position sensor
A capacitive position sensor for determining the position of an object along first and second directions is described. The sensor comprises a substrate having an arrangement of electrodes mounted on a single surface thereof. The electrodes are arranged so as to define an array of sensing cells arranged in columns and rows to form a sensing area. Each of the sensing cell including a column sensing electrode and a row sensing electrode with the column sensing electrodes of sensing cells in the same column being electrically coupled together and the row sensing electrodes of sensing cells in the same row also being electrically coupled together. Row sensing electrodes of sensing cells at opposing ends of at least one of the rows are connected together by an electrical connection made outside of the sensing area so that there is no requirement for electrical connections to cross within the sensing area, thus providing a capacitive position sensor having a sensing area with electrodes on only one side of a substrate.
1. A sensor comprising:
a sensing area;
a plurality of sensing cells arranged in the sensing area in a plurality of rows and columns, the sensing cells being configured to sense a position of an object within the sensing area, each of the sensing cells comprising a row-sensing electrode and a column-sensing electrode, the row-sensing electrode of each of one or more of the sensing cells being continuous with respect to the row-sensing electrode of each of one or more of the sensing cells adjacent to it in its row, the column-sensing electrode of each of one or more of the sensing cells being continuous with respect to the column-sensing electrode of each of one or more of the sensing cells adjacent to it in its column; and
a column wrap-around connection coupling a portion of the column-sensing electrode located at opposing ends of the columns of the sensing cells, the column wrap-around connection provided along a periphery of the sensing area.
2. The sensor of claim 1 , further comprising a row wrap-around connection coupled to a portion of the row-sensing electrode located at opposing ends of the rows of the sensing cells, the row wrap-around connection comprises a conductive trace deposited on the substrate along a periphery of the sensing area.
3. The sensor of claim 1 , wherein one or more of the row-sensing electrodes is continuous with respect to the row-sensing electrode of each of one or more of the sensing cells adjacent to it in its row and its column-sensing electrode is also continuous with respect to the column-sensing electrode of each of one or more of the sensing cells adjacent to it in its column.
4. The sensor of claim 1 , further comprising a plurality of capacitance measurement channels connected to respective ones of the row-sensing and column-sensing electrodes, wherein each measurement channel is operable to generate a signal indicative of a capacitance between its associated row-sensing or column-sensing electrodes and a system ground.
5. The sensor of claim 1 , wherein the column-sensing electrode and the row-sensing electrode in each sensing cell are spirally interleaved with one another.
6. The sensor of claim 1 , wherein the sensing area is defined on a substrate comprising a transparent material.
7. The sensor of claim 1 , wherein the row-sensing and column-sensing electrodes comprise a transparent electrically conductive material.
8. A method comprising:
sensing a position of an object within a sensing area, the sensing area comprising a plurality of sensing cells arranged in a plurality of rows and columns, the sensing cells being configured to sense a position of an object within the sensing area, each of the sensing cells comprising a row-sensing electrode and a column-sensing electrode, the row-sensing electrode of each of one or more of the sensing cells being continuous with respect to the row-sensing electrode of each of one or more of the sensing cells adjacent to it in its row, the column-sensing electrode of each of one or more of the sensing cells being continuous with respect to the column-sensing electrode of each of one or more of the sensing cells adjacent to it in its column, a column wrap-around connection coupling a portion of the column-sensing electrode located at opposing ends of the columns, the column wrap-around connection provided along a periphery of the sensing area; and
communicating a plurality of signals resulting from a capacitance sensed by the row-sensing and column-sensing electrodes and-indicative of the position of the object within the sensing area.
9. The method of claim 8 , wherein the sensing area further comprises a row wrap-around connection coupled to a portion of the row-sensing electrode located at opposing ends of the rows of the sensing cells, the row wrap-around connection comprises a conductive trace deposited on the substrate along a periphery of the sensing area.
10. The method of claim 8 , wherein one or more of the row-sensing electrodes of each of one or more of the sensing cells is continuous with respect to the row-sensing electrode of each of one or more of the sensing cells adjacent to it in its row and its column-sensing electrode is also continuous with respect to the column-sensing electrode of each of one or more of the sensing cells adjacent to it in its column.
11. The method of claim 8 , wherein the column-sensing and row-sensing electrodes in each sensing cell are spirally interleaved with one another.
12. The method of claim 8 , wherein the sensing area is defined on a substrate comprising transparent material.
13. The method of claim 8 , wherein the row-sensing and column-sensing electrodes comprise a transparent electrically conductive material.
14. The method of claim 8 , wherein the sensing area comprises a plurality of capacitance measurement channels connected to respective ones of the row-sensing and column-sensing electrodes, wherein each measurement channel is operable to generate a signal indicative of a capacitance between its associated row-sensing or column-sensing electrodes and a system ground.
15. A computer-readable non-transitory storage media embodying logic that is operable when executed to:
sense a position of an object within a sensing area, the sensing area comprising a plurality of sensing cells arranged in a plurality of rows and a plurality of columns, the sensing cells being configured to sense a position of an object within the sensing area, each of the sensing cells comprising a row-sensing electrode and a column-sensing electrode, the row-sensing electrode of each of one or more of the sensing cells being continuous with respect to the row-sensing electrode of each of one or more of the sensing cells adjacent to it in its row, the column-sensing electrode of each of one or more of the sensing cells being continuous with respect to the column-sensing electrode of each of one or more of the sensing cells adjacent to it in its column, a column wrap-around connection coupling a portion of the column-sensing electrode located at opposing ends of the columns, the column wrap-around connection provided along a periphery of the sensing area; and
communicate a plurality of signals resulting from a capacitance sensed by the row-sensing and column-sensing electrodes indicative of the position of the object within the sensing area.
16. The media of claim 15 , wherein one or more of the row-sensing electrodes of each of one or more of the sensing cells is continuous with respect to the row-sensing electrode of each of one or more of the sensing cells adjacent to it in its row and its column-sensing electrode is also continuous with respect to the column-sensing electrode of each of one or more of the sensing cells adjacent to it in its column.
17. The media of claim 15 , wherein the sensing area is defined on a substrate comprising transparent material.
18. The media of claim 15 , wherein the row-sensing column-sensing electrodes comprise a transparent electrically conductive material.
19. The media of claim 15 , wherein the sensing area further comprises a row wrap-around connection coupled to a portion of the row-sensing electrode located at opposing ends of the rows of the sensing cells, the row wrap-around connection comprises a conductive trace deposited on the substrate along a periphery of the sensing area.
20. The media of claim 15 , wherein the sensing area further comprises a plurality of capacitance measurement channels connected to respective ones of the row-sensing and column-sensing electrodes, wherein each measurement channel is operable to generate a signal indicative of a capacitance between its associated row-sensing or column-sensing electrodes and a system ground.
21. The media of claim 15 , wherein the column-sensing and row-sensing electrodes in each sensing cell are spirally interleaved with one another.