Capacitive Keyboard with Position Dependent Reduced Keying Ambiguity

• US 20070273561A1
• Filed: 05/18/2007
• Published: 11/29/2007
• Est. Priority Date: 05/25/2006
• Status: Active Grant

• Current Assignee: Neodrón Limited (Atlantic IP Services Limited)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Philipp, Harald
• Granted Patent: US 7,903,092 B2
• Time in Patent Office: Days
• US Class Current: 341/33
• CPC Class Codes: G06F 3/04886 by partitioning the display area of the touch-screen or the surface of the digitising tablet into independently controllable areas, e.g. virtual keyboards or menus
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard

Abstract

Apparatus and methods are described for selecting which of a plurality of simultaneously activated keys in a keyboard based on capacitive sensors is a key intended for selection by a user. In embodiments of the invention keys are preferentially selected as the user intended key based on their positions within the keyboard. Thus a key which is frequently wrongly activated when a user selects another key, e.g. because the key is adjacent the intended key and the user normally passes his finger over it while approaching the desired key, can be suppressed relative to the desired key based on their relative positions. For example, keys may be associated with predefined rankings according to their position within the keyboard and in use keys are preferentially select according to their rankings. Alternatively, signals from the keys may be scaled by weighting factors associated with their positions and a key selected according to the weighted signals.

Claims

1. A touch-sensitive user interface, comprising:

a plurality of sensing areas arranged within a sensing region, each sensing area having a position within the sensing region;

a measurement circuit coupled to the sensing areas and operable to generate output signals responsive to a coupling between a pointing object and respective ones of the sensing areas; and

a controller operable to receive the output signals from the measurement circuit and to determine a selected one of the sensing areas by taking account of both the output signals associated with the sensing areas and the positions of the sensing areas within the sensing region.

2. A touch-sensitive user interface according to claim 1, wherein the coupling is a capacitive coupling.

3. A touch-sensitive user interface according to claim 1, wherein each sensing area is associated with a predefined ranking according to its position within the sensing region, and the controller is operable to preferentially select sensing areas according to their ranking.

4. A touch-sensitive user interface according to claim 1, wherein the controller is arranged to determine the selected one of the sensing areas by applying a weighting to the output signals according to the positions of the corresponding sensing areas in the sensing region.

5. A touch-sensitive user interface according to claim 4, wherein the weighting is applied by scaling the output signals by a scale factor associated with the corresponding sensing areas according to their positions in the sensing region, and the controller is operable to determine the selected one of the sensing areas based on a comparison of the scaled output signals.

6. A touch-sensitive user interface according to claim 1, wherein the controller is operable to take account of the positions of the sensing areas within the sensing region when determining the selected one of the sensing areas by preferentially selecting sensing areas having positions located nearer to predefined parts of the sensing region over sensing areas having positions located farther from the predefined parts of the sensing region.

7. A touch-sensitive user interface according to claim 1, wherein in normal use a pointing object approaches the sensing region from a normal approach direction, and wherein sensing areas are preferentially selected according to their positions along the normal approach direction.

8. A touch-sensitive user interface according to claim 1, wherein in normal use the pointing object approaches the sensing region from one of a plurality of normal approach directions, and wherein sensing areas are preferentially selected according to their positions along the normal approach directions.

9. A touch-sensitive user interface according to claim 1, wherein the sensing areas are arranged in rows and columns, and wherein sensing areas in one row are preferentially selected over sensing areas in another row.

10. A touch-sensitive user interface according to claim 1, wherein the sensing areas are arranged in rows and columns, and wherein sensing areas in one column are preferentially selected over sensing areas in another column.

11. A touch-sensitive user interface according to claim 1, further comprising a further plurality of sensing areas arranged within a further sensing region, each further sensing area having a position within the further sensing region, wherein the measurement circuit coupled to the further sensing areas and operable to generate further output signals responsive to a coupling between the pointing object and respective ones of the further sensing areas;

and wherein the controller is further operable to receive the further output signals from the measurement circuit and to determine a selected one of the further sensing areas by taking account of both the further output signals associated with the further sensing areas and the positions of the further sensing areas within the further sensing region.

12. A touch-sensitive user interface according to claim 11, wherein the controller is further operable to determine a selected one of the selected one of the first-mentioned sensing areas and the selected one of the further sensing areas based on the output signals associated with these selected sensing areas.

13. An apparatus comprising a touch-sensitive user interface according to claim 1.

14. A method for determining which one of a plurality of sensing areas in a sensing region of a touch-sensitive user interface is selected by a pointing object, the method comprising:

measuring a coupling between the pointing object and respective ones of the sensing areas and generating output signals responsive thereto; and

determining one of the sensing areas to be the selected sensing area by taking account both the output signals associated with the sensing areas and the positions of the sensing areas within the sensing region.

15. A method according to claim 14, wherein the coupling is a capacitive coupling.