TOUCH DETECTION IN A CAPACITIVE SENSOR SYSTEM

• US 20150301735A1
• Filed: 01/16/2015
• Published: 10/22/2015
• Est. Priority Date: 04/17/2014
• Status: Active Grant

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Microchip Technology Incorporated
• Inventors: Hoch, Martin, Heim, Axel
• Granted Patent: US 10,459,623 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 2203/04101 2.5D-digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface and also measures the distance of the input means within a short range in the Z direction, possibly with a separate measurement setup
• CPC Class Codes: G06F 2203/04106 Multi-sensing digitiser, i.e. digitiser using at least two different sensing technologies simultaneously or alternatively, e.g. for detecting pen and finger, for saving power or for improving position detection
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• 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
• CPC Class Codes: G06F 3/04883 for inputting data by handwriting, e.g. gesture or text

Abstract

A system has a two-dimensional (2D) touch detection system operable to be activated and de-activated and an additional sensor operable in communication with the 2D touch detection system. The additional sensor is capable to determine whether a touch event has occurred or is about to occur and to activate the 2D touch detection system if a touch event has occurred or is about to occur.

Claims

1. A system comprising:

a two-dimensional (2D) touch detection system operable to be activated and de-activated;

an additional sensor operable in communication with the 2D touch detection system;

wherein the additional sensor is capable to determine whether a touch event has occurred or is about to occur and to activate the 2D touch detection system if a touch event has occurred or is about to occur.

2. The system according to claim 1,

wherein the additional sensor is a three-dimensional (3D) gesture detection system.

3. The system according to claim 2,

wherein for determination of a touch event, the 3D gesture detection system uses a stochastic filter for noise suppression.

4. The system according to claim 3, wherein the stochastic filter is an Unscented Kalman filter.

5. The system according to claim 3, wherein the stochastic filter suppresses sinusoidal noise.

6. The system according to claim 2, wherein the 3D gesture detection system comprises a plurality of receiving electrodes configured to determine a gesture and a touch detection electrode.

7. The system according to claim 2, wherein the 3D gesture detection system comprises a plurality of receiving electrodes configured to determine a gesture and shares at least one electrode from the touch detection system as a touch detection electrode.

8. The system according to claim 7, further comprising a multiplexer switch configured to share the at least one electrode between the 3D gesture detection system and the 2D touch detection system.

9. The system according to claim 2, wherein the 3D gesture detection system comprises a plurality of receiving electrodes configured to determine a gesture and a multiplexer configured to share at least one electrode from the touch detection system to operate as a transmission electrode for the 3D gesture detection system.

10. The system according to claim 6, wherein the touch detection electrode covers an area used by the 2D touch detection system.

11. The system according to claim 10, wherein a difference signal of subsequent samples from the touch detection electrode is generated and evaluated over time.

12. The system according to claim 11, wherein the difference signal is fed to an Unscented Kalman Filter.

13. The system according to claim 12, wherein an output signal of the Unscented Kalman Filter is subtracted from the difference signal and fed to a threshold comparison unit which is configured to output a touch event signal.

14. The system according to claim 11, wherein the system determines whether a touch occurred by evaluating whether a characteristic bent in the difference signal is present near the crossing of the zero-line of the difference signal.

15. The system according to claim 1, wherein the 2D touch detection system is a capacitive touch detection system.

16. The system according to claim 15, wherein the capacitive touch detection system comprises a projected capacitive touch controller.

17. A method for operating an input device, comprising:

providing a two-dimensional (2D) touch detection system operable to be activated and de-activated;

providing another sensor system operable to be in communication with the 2D touch detection system;

activating the other sensor system and deactivating the 2D touch detection system;

determining by the other sensor system whether a touch event has occurred or is about to occur; and

activating the 2D touch detection system if a touch event has occurred or is about to Occur.

18. The method according to claim 17, wherein the other sensor system is a three-dimensional (3D) gesture detection system.

19. The method according to claim 18,

wherein for determination of a touch event, the 3D gesture detection system uses a stochastic filter for noise suppression.

20. The method according to claim 19, wherein the stochastic filter is an Unscented Kalman filter.

21. The method according to claim 19, wherein the stochastic filter suppresses sinusoidal noise.

22. The method according to claim 18, wherein the 3D gesture detection system comprises a plurality of receiving electrodes configured to determine a gesture and a touch detection electrode.

23. The method according to claim 18, wherein the 3D gesture detection system comprises a plurality of receiving electrodes configured to determine a gesture and the method comprises the step of sharing at least one electrode from the touch detection system as a touch detection electrode.

24. The method according to claim 23, wherein sharing is performed by controlling a multiplexer switch configured to share the at least one electrode between the 3D gesture detection system and the 2D touch detection system.

25. The method according to claim 18, wherein the 3D gesture detection system comprises a plurality of receiving electrodes configured to determine a gesture and the method comprises the step of sharing at least one electrode from the touch detection system to operate as a transmission electrode for the 3D gesture detection system.

26. The method according to claim 22, wherein the touch detection electrode covers an area used by the 2D touch detection system.

27. The method according to claim 26, wherein a difference signal of subsequent samples from the touch detection electrode is generated and evaluated over time.

28. The method according to claim 27, comprising filtering the difference signal by an Unscented Kalman Filter.

29. The method according to claim 28, comprising subtracting the filtered signal from the difference signal and feeding the subtracted signal to a threshold comparison unit which outputs a touch event signal.

30. The method according to claim 27, comprising determining whether a touch occurred by evaluating whether a characteristic bent in the difference signal is present near the crossing of the zero-line of the difference signal.

31. The method according to claim 17, wherein the 2D touch detection system is a capacitive touch detection system.

32. The method according to claim 31, wherein the capacitive touch detection system comprises a projected capacitive touch controller.