Sensitivity control as a function of touch shape

• US 8,451,237 B2
• Filed: 07/06/2009
• Issued: 05/28/2013
• Est. Priority Date: 07/06/2009
• Status: Active Grant

• Current Assignee: Neodrón Limited (Atlantic IP Services Limited)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Sleeman, Peter
• Primary Examiner(s): Sharifi-Tafreshi, Koosha
• Application Number:
  US12/498,317
• Publication Number:
  US 20110001708A1
• Time in Patent Office: 1,422 Days
• Field of Search: 345173-175, 345/179, 178/18.01, 178/18.09
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers

Abstract

A method and device receives signals from a plurality of nodes about a first touch of an array of touch screen sensor nodes. It is determined whether the received signals are representative of a finger touch or a stylus touch. A detect mode may be entered as a function of the type of touch determined.

Claims

1. A machine implemented method comprising:

receiving signals from a plurality of nodes about a first touch of an array of touch screen sensor nodes;

determining, using a first detection threshold, whether the received signals are representative of a finger touch or a stylus touch; and

entering a detect mode as a function of whether the received signals are determined to be representative of a finger touch or a stylus touch, the detect mode comprising a mode in which subsequent touches are interpreted with a second threshold that is lower than the first detection threshold;

wherein the first and second thresholds each represent a corresponding capacitance.

2. The method of claim 1 comprising determining, when the received signals have a strong center peak surrounded by a halo region, that the received signals are representative of a finger touch.

3. The method of claim 2 wherein a small finger touch corresponds to received signals having a slightly smaller center peak and halo region than a large finger touch.

4. The method of claim 2 comprising determining, when the received signals have a slightly weaker center peak as compared to a finger touch and small halo, that the received signals are representative of a stylus touch.

5. The method of claim 1 wherein the first detection threshold is set to be more sensitive for a stylus touch than for a finger touch.

6. The method of claim 1 comprising using the second detection threshold to detect further touches consistent with the first touch.

7. The method of claim 6 comprising using the second detection threshold for a predetermined amount of time following the first touch.

8. The method of claim 1 wherein the second detection threshold is localized to sensor nodes proximate the first touch.

9. The method of claim 8 and further comprising:

receiving signals from a plurality of nodes about a second touch of the array of touch screen sensor nodes physically separated from the first touch;

determining whether the received signals from the second touch are representative of a finger touch or a stylus touch; and

entering a detect mode as a function of the type of the second touch determined such that multiple detection thresholds are localized about the array of touch screen sensors.

10. A machine implemented method comprising:

detecting, based on scanning nodes in an array of touch screen sensor nodes, a touch associated with one or more signals;

interpreting, when the one or more signals are above a first detection touch threshold, the touch as a finger touch;

quantifying, when the one or more signals are below the first detection touch threshold but above a second detection touch threshold, nodes surrounding a particular node associated with the touch;

interpreting, when the quantification of the surrounding nodes is indicative of a stylus touch, the touch as a stylus touch; and

entering a detect mode as a function of whether the touch is interpreted as a finger touch or a stylus touch, the detect mode comprising a mode in which subsequent touches are interpreted with a third detection touch threshold that is lower than the first detection touch threshold;

wherein the first and second thresholds each represent a corresponding capacitance.

11. The method of claim 10 wherein quantifying surrounding nodes comprises quantifying a center of the touch and quantifying a halo around the center of the touch.

12. The method of claim 11 wherein the quantification of the center of the touch and the halo comprise a shape of the touch.

13. The method of claim 12 wherein the shape of the touch is compared to known shapes of finger touches and stylus touches to determine the type of touch.

14. The method of claim 12 wherein the shape of the touch is compared to known statistical distributions of signals associated with known shapes of touches to determine the type of touch.

15. The method of claim 12 wherein the shape of the touch is correlated to a signal weighting matrix to determine the type of touch.

16. A system comprising:

a touchscreen having a plurality of sensor nodes to provide signals from the plurality of nodes about a first touch of an array of touch screen sensor nodes;

a controller communicatively coupled to the touchscreen sensor nodes, the controller configured to;

receive the signals;

determine, using a first detection threshold, whether the received signals are representative of a finger touch or a stylus touch; and

enter a detect mode as a function of the type of touch determined, the detect mode comprising a mode in which subsequent touches are interpreted with a second threshold that is lower than the first detection threshold;

wherein the first and second thresholds each represent a corresponding capacitance.

17. The system of claim 16 wherein the controller further is coupled to the nodes and is configured to:

receive signals from a plurality of nodes about a second touch of the array of touch screen sensor nodes physically separated from the first touch;

determine whether the received signals from the second touch are representative of a finger touch or a stylus touch; and

set an internal detection threshold as a function of the type of the second touch determined such that multiple detection thresholds are localized about the array of touch screen sensors.

18. The system of claim 16 wherein the controller is configured to determine, when the received signals have a strong center peak surrounded by a halo region, that the received signals are representative of a finger touch.

19. The system of claim 18 wherein a small finger touch corresponds to received signals having a slightly smaller center peak and halo region than a large finger touch.

20. The system of claim 18 wherein the controller is configured to determine, when the received signals have a slightly weaker center peak as compared to a finger touch and small halo, that the received signals are representative of a stylus touch.

21. The system of claim 16 wherein the first detection threshold is set to be more sensitive for a stylus touch than for a finger touch.

22. The system of claim 16 wherein the controller is configured to use the second detection threshold to detect further touches consistent with the first touch.

23. The system of claim 22 wherein the controller is configured to use the second detection threshold for a predetermined amount of time following the first touch.

24. The system of claim 16 wherein the second detection threshold is localized to sensor nodes proximate the first touch.