Two-dimensional position sensor

• US 7,821,502 B2
• Filed: 07/05/2006
• Issued: 10/26/2010
• Est. Priority Date: 07/08/2005
• Status: Active Grant

• Current Assignee: Neodrón Limited (Atlantic IP Services Limited)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Hristov, Luben
• Primary Examiner(s): Kumar, Srilakshmi K
• Application Number:
  US11/428,670
• Publication Number:
  US 20070008299A1
• Time in Patent Office: 1,574 Days
• Field of Search: 345/156, 345173-178, 178/18.01, 178/18.06
• US Class Current: 345/173
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• CPC Class Codes: G06F 3/04186 Touch location disambiguation
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: G06F 3/0448 Details of the electrode shape, e.g. for enhancing the detection of touches, for generating specific electric field shapes, for enhancing display quality
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

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.

Claims

1. A position sensor comprising:

a substrate having a surface with an arrangement of electrodes mounted thereon,

wherein the electrodes define an array of sensing cells arranged in columns and rows to form a capacitive sensing area of the sensor, each sensing cell including a column sensing electrode and a row sensing electrode, 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 being electrically coupled together, and

wherein row sensing electrodes of sensing cells at opposing ends of at least one of the rows are electrically coupled to one another by respective row wrap-around connections made outside of the sensing area.

2. The position sensor of 1, wherein the row wrap-around connections comprise a conductive trace deposited on the substrate.

3. The position sensor of 1, wherein the row wrap-around connections comprise free wires connected to the respective row sensing electrodes.

4. The position sensor of 1, wherein the column sensing electrodes of a column of sensing cells at an edge of the sensing area are electrically coupled to one another by column wrap-around connections made outside of the sensing area.

5. The position sensor of 1, further comprising a plurality of capacitance measurement channels connected to respective ones of the rows and columns of sensing electrodes, wherein each measurement channel is operable to generate a signal indicative of a capacitance between its associated column or row of sensing electrodes and a system ground.

6. The position sensor of 5, further comprising a processor operable to determine the position of the object in the sensing area along a first direction by comparing signals from the different columns with each other and along a second direction by comparing signals from the different rows with each other.

7. The position sensor of 5, wherein the capacitance measurement channels comprise a charge transfer circuit.

8. The position sensor of 5, wherein the capacitance measurement channels are configured to drive a plurality of sensing electrodes substantially synchronously in phase with one another.

9. The position sensor of 1, wherein the sensing cells are arranged into three columns.

10. The position sensor of 1, wherein the sensing cells are arranged into four columns.

11. The position sensor of 1, wherein the column sensing electrode and the row sensing electrode in each sensing cell are interleaved with one another.

12. The position sensor of 1, wherein the substrate is formed from a transparent material.

13. The position sensor of 1, wherein the electrodes are formed from a transparent electrically conductive material.

14. The position sensor of 13, further comprising a graphical display wherein the electrodes in the sensing area are disposed over the graphical display to provide a touch screen.

15. The position sensor of 1, further comprising an insulating panel wherein the electrodes in the sensing area are disposed beneath the insulating panel to provide a keypad.

16. A device comprising the position sensor of 1.

17. A method comprising:

depositing a single layer of patterned conductive material on a substrate to form an active sensing region of a capacitive sensor, the pattern comprising rows and columns of electrodes connected to individual ones of capacitive sensing channels, and wherein at least one row or column is broken into a plurality of segments within the active sensing region;

connecting a first broken segment at a first end of one of the at least one row or column to a second broken segment at a second end of the one of the at least one row or column using a wrap-around connection lying outside of the active sensing region, the plurality of segments including the first broken segment and the second broken segment;

connecting the rows and columns to individual sensing channels of a multi-channel capacitive sensor circuit having multiple outputs representing amplitudes of capacitance on the rows and columns; and

providing a processor operable to process the multiple outputs to determine a XY coordinate position of an object adjacent the active sensing region.

18. The method of 17, wherein the processor is operable to compensate for position distortion introduced by the physical geometry of the patterned conductive, material.

19. The method of 17, wherein the processor is operable to calculate a centroid of the signals across rows and a centroid of the signals across columns.

20. The method of 17, wherein the processor is operable to calculate an interpolation of the signals across rows and an interpolation of the signals across columns.

21. The method of 17, wherein the capacitive sensing channels employ driving signals which are substantially phase-synchronous with respect to one another.

22. A capacitive position sensor for determining the position of an object in a sensing area, the sensor comprising a substrate having a surface with an arrangement of conductive electrodes mounted thereon, wherein the electrodes define an array of sensing cells arranged in columns and rows to form the sensing area, each sensing cell including a column sensing electrode and a row sensing electrode, 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 being electrically coupled together, wherein at least one column sensing electrode comprises a continuous spine within the sensing area, and at least one other column sensing electrode is made electrically continuous via connections external to the sensing area.

23. The position sensor of 22, wherein the conductive electrodes are transparent and further comprising a graphical display wherein the conductive electrodes in the sensing area are disposed over the graphical display to provide a touch screen.

24. The position sensor of 22, further comprising an insulating panel wherein the conductive electrodes in the sensing area are disposed beneath the insulating panel to provide a keypad.