Capacative Position Sensor

• US 20080278178A1
• Filed: 05/02/2008
• Published: 11/13/2008
• Est. Priority Date: 05/07/2007
• Status: Active Grant

• Current Assignee: Neodrón Limited (Atlantic IP Services Limited)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Philipp, Harald
• Granted Patent: US 7,821,274 B2
• Time in Patent Office: Days
• US Class Current: 324/662
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A sensor for determining a position for an adjacent object in two dimensions is described. The sensor comprises a substrate with a sensitive area defined by a pattern of electrodes, wherein the pattern of electrodes includes a first group of drive elements interconnected to form a plurality of row electrodes extending along a first direction, a second group of drive elements interconnected to form a plurality of column electrodes extending along a second direction, and a group of sense elements interconnected to form a sense electrode extending along both the first and second directions. The sensor further comprises a controller comprising a drive unit for applying drive signals to the row and column electrodes, and a sense unit for measuring sense signals representing a degree of coupling of the drive signals applied to the row and column electrodes to the sense electrode. Thus a 2D position sensor requiring only a single sense channel is provided.

Claims

1. A sensor for determining a position for an object in two dimensions, the sensor comprising a substrate with a sensitive area defined by a pattern of electrodes, wherein the pattern of electrodes includes a first group of drive elements interconnected to form a plurality of row electrodes extending along a first direction, a second group of drive elements interconnected to form a plurality of column electrodes extending along a second direction, and a group of sense elements interconnected to form a sense electrode extending along both the first and second directions.

2. A two-dimensional position sensor according to claim 1, wherein the sensor further comprises a controller comprising a drive unit for applying drive signals to the row and column electrodes, and a sense unit for measuring sense signals representing a degree of coupling of the drive signals applied to the row and column electrodes to the sense electrode.

3. A two-dimensional position sensor according to claim 1, wherein the controller further comprises a processing unit for calculating a position for the object in one direction from an analysis of the sense signals obtained by applying drive signals to different ones of the row electrodes, and calculating a position for the object in another direction from an analysis of the sense signals obtained by applying drive signals to different ones of the column electrodes.

4. A two-dimensional position sensor according to claim 1, wherein the first group of drive elements and the second group of drive elements are located on opposite sides of the substrate.

5. A two-dimensional position sensor according to claim 1, wherein the first group of drive elements and the second group of drive elements are located on the same side of the substrate.

6. A two-dimensional position sensor according to claim 5, wherein connections for connecting the first group of drive elements into the row electrodes are made within the sensitive area of the sensor and connections for connecting the second group of drive elements into the column electrodes are made at least partially outside of the sensitive area of the sensor.

7. A two-dimensional position sensor according to claim 6, wherein the connections for connecting the second group of drive elements into the column electrodes include connection portions within the sensitive area of the sensor which extend in the same direction as the row electrodes from respective ones of the drive elements to a periphery of the sensitive area of the sensor.

8. A two-dimensional position sensor according to claim 6, wherein drive elements in at least one of the column electrodes include passageways to allow connections from drive elements in another column electrode to pass through.

9. A two-dimensional position sensor according to claim 8, wherein portions of drive elements on either side of the passageways are connected together by connections made at least partially outside of the sensitive area of the sensor.

10. A two-dimensional position sensor according to claim 9, wherein the connections for connecting the portions of drive elements on either side of the passageways include connection portions within the sensitive area of the sensor which extend in the same direction as the row electrodes to a periphery of the sensitive area of the sensor.

11. A two-dimensional position sensor according to claim 5, wherein the group of sense elements are located on the same side of the substrate as the first and second groups of drive elements.

12. A two-dimensional position sensor according to claim 11, wherein connections for connecting the sense elements into the sense electrode are made at least partially outside of the sensitive area of the sensor.

13. A two-dimensional position sensor according to claim 12, wherein the connections for connecting the sense elements into the sense electrode include connection portions within the sensitive area of the sensor which extend in the same direction as the row electrodes from respective ones of the sense elements to a periphery of the sensitive area of the sensor.

14. A two-dimensional position sensor according to claim 6, wherein at least one of the sense elements includes a passageway to allow connections from drive elements in a column electrode to pass through.

15. A two-dimensional position sensor according to claim 14, wherein portions of the at least one of the sense elements on either side of the passageway are connected together by connections made at least partially outside of the sensitive area of the sensor.

16. A two-dimensional position sensor according to claim 15, wherein the connections for connecting the portions of the at least one of the sense elements on either side of the passageway include connection portions within the sensitive area of the sensor which extend in the same direction as the row electrodes to a periphery of the sensitive area of the sensor.

17. A two-dimensional position sensor according to claim 1, wherein the row electrodes and the column electrodes are orthogonal to one another.

18. An apparatus comprising a two-dimensional position sensor according to claim 1.