Capacitive touch screen with force detection

• US 9,141,225 B2
• Filed: 05/31/2013
• Issued: 09/22/2015
• Est. Priority Date: 05/31/2013
• Status: Active Grant

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Cok, Ronald Steven, Markham, Roger G.
• Primary Examiner(s): NGUYEN, KEVIN M
• Application Number:
  US13/906,506
• Publication Number:
  US 20140354585A1
• Time in Patent Office: 844 Days
• Field of Search: 345/173, 345/179
• US Class Current: 1/1
• CPC Class Codes: G06F 3/04186 Touch location disambiguation
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells

Abstract

A capacitive touch-screen device with force detection of a deformable touch element includes drive and sense electrode arrays and a touch-detection circuit connected to the electrodes for detecting capacitance at a touch location. The touch-detection circuit senses no-touch capacitance, light-touch capacitance, and heavy-touch capacitance at the touch location in response to forcible deformation of the deformable touch element proximate to the touch. The touch-detection circuit reports a force signal.

Claims

1. A capacitive touch-screen device with force detection of a deformable touch element, comprising:

a first array of drive electrodes and a second array of sense electrodes in association with a touch-detection area on a surface of a touch screen; and

a touch-detection circuit connected to the drive electrodes and connected to the sense electrodes for detecting capacitance at a touch location in the touch-detection area, the touch-detection circuit for;

sensing no-touch capacitance with the touch-detection circuit at the touch location in the absence of the deformable touch element proximate to the touch location and reporting a no-touch signal;

sensing light-touch capacitance different from the no-touch capacitance with the touch-detection circuit at the touch location in the presence of a light-touch deformation of the same deformable touch element on the surface proximate to the touch location and reporting a light-touch signal at least partially responsive to a touch area of the light-touch deformation;

sensing heavy-touch capacitance different from both the no-touch capacitance and the light-touch capacitance with the touch-detection circuit at the touch location in the presence of a heavy-touch deformation of the same deformable touch element on the surface proximate to the touch location and reporting a heavy-touch signal at least partially responsive to a touch area of the heavy touch deformation greater than the touch area of the light-touch deformation; and

determining a sequential progression of sensed capacitance values from no-touch to light-touch to heavy-touch indicating a sequential series of progressively more forceful touches or determining a sequential progression of sensed capacitance values from heavy-touch to light-touch to no-touch indicating a sequential series of progressively less forceful touches.

2. The capacitive touch-screen device of claim 1, wherein the drive electrodes extend across the touch-detection area in a first direction and the sense electrodes extend across the touch-detection area in a second direction different from the first direction.

3. The capacitive touch-screen device of claim 1, wherein the touch detection circuit further includes circuits for calculating a light-touch ratio between the light-touch capacitance and the no-touch capacitance and reporting a light-touch signal in response to the ratio or in response to a value produced using the ratio.

4. The capacitive touch-screen device of claim 1, wherein the touch detection circuit further includes circuits for calculating a heavy-touch ratio between the heavy-touch capacitance and the no-touch capacitance and reporting a heavy-touch signal in response to the ratio or in response to a value produced using the ratio.

5. The capacitive touch-screen device of claim 1, wherein the touch detection circuit further includes circuits for calculating a light-touch ratio between the light-touch capacitance and the no-touch capacitance, calculating a heavy-touch ratio between the heavy-touch capacitance and the no-touch capacitance, and wherein the light-touch ratio is closer to one than the heavy-touch ratio.

6. The capacitive touch-screen device of claim 1, wherein the touch detection circuit further includes circuits for reporting the touch location.

7. The capacitive touch-screen device of claim 1, wherein the deformable touch element is a finger.

8. The capacitive touch-screen device of claim 1, wherein the average distance between the deformable touch element and the drive or sense electrodes is smaller for a heavy-touch deformation than for a light-touch deformation.

9. The capacitive touch-screen device of claim 1, wherein the touch detection circuit further includes circuits for repeatedly sensing the no-touch capacitance, the light-touch capacitance, or the heavy-touch capacitance over time.

10. A capacitive touch-screen device for force detection of a deformable touch element with a capacitive touch-screen device, comprising:

a first array of drive electrodes and a second array of sense electrodes in association with a touch-detection area on a surface of a touch screen; and

a touch-detection circuit connected to the drive electrodes and connected to the sense electrodes for detecting capacitance at multiple touch locations in the touch-detection area, the touch-detection circuit for;

sensing no-touch capacitance with the touch-detection circuit at the multiple touch locations in the absence of the deformable touch element proximate to the multiple touch locations and reporting a no-touch signal;

sensing light-touch capacitance different from the no-touch capacitance with the touch-detection circuit at the multiple touch locations in the presence of a light-touch deformation of the same deformable touch element on the surface proximate to the multiple touch locations and reporting a light-touch signal at least partially responsive to a touch area of the light-touch deformation;

sensing heavy-touch capacitance different from both the no-touch capacitance and the light-touch capacitance with the touch-detection circuit at the multiple touch locations in the presence of a heavy-touch deformation of the same deformable touch element on the surface proximate to the multiple touch locations and reporting a heavy-touch signal at least partially responsive to a touch area of the heavy-touch deformation greater than the touch area of the light-touch deformation; and

determining a sequential progression of sensed capacitance values from no-touch to light-touch to heavy-touch indicating a sequential series of progressively more forceful touches or determining a sequential progression of sensed capacitance values from heavy-touch to light-touch to no-touch indicating a sequential series of progressively less forceful touches.

11. The capacitive touch-screen device of claim 10, wherein the touch-detection circuit further includes circuits for reporting a heavy-touch signal at a first number of touch locations, reporting a light-touch signal at a second number of touch locations, and wherein the first number is greater than the second number.

12. The method of claim 10, wherein each of the touch locations reporting a heavy touch or reporting a light touch is adjacent to another touch location reporting a heavy touch or reporting a light touch.

13. The method of claim 12, wherein the touch locations reporting a heavy touch or reporting a light touch form a substantially circular or oval perimeter.

14. The capacitive touch-screen device of claim 10, wherein the deformable touch element has a center and wherein the difference between the light-touch capacitance and the no-touch capacitance sensed for touch locations farther from the center is smaller than the difference between the light-touch capacitance and the no-touch capacitance sensed for touch locations closer to the center.

15. The capacitive touch-screen device of claim 10, wherein the deformable touch element has a center and wherein the difference between the heavy-touch capacitance and the no-touch capacitance sensed for touch locations farther from the center is smaller than the difference between the heavy-touch capacitance and the no-touch capacitance sensed for touch locations closer to the center.

16. The capacitive touch-screen device of claim 10 wherein:

the deformable touch element has a center located nearest a center touch location and adjacent touch locations are located adjacent the center touch location; and

wherein the heavy-touch capacitance sensed for the adjacent touch locations are closer to the heavy-touch capacitance sensed for the center touch location than the light-touch capacitance sensed for the adjacent touch location are to the light-touch capacitance sensed for the center touch location.

17. The capacitive touch-screen device of claim 10, wherein the touch-detection circuit further includes circuits for reporting a touch location at the touch location whose measured capacitance has the greatest difference from the sensed no-touch capacitance.

18. The capacitive touch-screen device of claim 10, wherein the touch-detection circuit further includes circuits for producing the touch area by comparing sensed capacitance to a pre-determined threshold value or by comparing a ratio of sensed capacitance to the sensed no-touch capacitance to a pre-determined threshold value for multiple adjacent touch locations.

19. The capacitive touch-screen device of claim 10, wherein the touch-detection circuit further includes circuits for reporting a touch force responsive to the area of the calculated touch area.

20. The capacitive touch-screen device of claim 10, wherein the touch-detection circuit further includes circuits for reporting a touch location at the center or centroid of the touch area.

21. A capacitive touch-screen device for force detection of a deformable touch element in a capacitive touch-screen device, comprising:

a first array of drive electrodes and a second array of sense electrodes in association with a touch-detection area on a surface of a touch screen, and;

a touch-detection circuit connected to the drive electrodes and connected to the sense electrodes for detecting capacitance at a touch location in the touch-detection area, the touch-detection circuit for;

sensing a no-touch capacitance with the touch-detection circuit at the touch location in the absence of a deformable touch element proximate to the touch location and reporting a no-touch signal;

sensing a touch capacitance different from the no-touch capacitance with the touch-detection circuit at the touch location in the presence of the same deformable touch element on the surface proximate to the touch location at least partially responsive to a touch area of the deformable touch element on the surface;

determining a sequential progression of sensed capacitance values from no-touch to light-touch to heavy-touch indicating a sequential series of progressively more forceful touches or determining a sequential progression of sensed capacitance values from heavy-touch to light-touch to no-touch indicating a sequential series of progressively less forceful touches;

producing a force signal associated with the touch capacitance; and

reporting the force signal.

22. The capacitive touch-screen device of claim 21, wherein the touch-detection circuit further includes circuits for calculating the force signal by comparing the touch capacitance to a range of touch capacitance values.

23. The capacitive touch-screen device of claim 21, wherein the touch-detection circuit further includes circuits for calibrating the force signal by comparing the touch capacitance to a range of touch capacitance values.

24. The capacitive touch-screen device of claim 21, wherein the touch-detection circuit further includes circuits for producing the force signal from a linear or logarithmic interpolation between the no-touch capacitance and a maximum touch capacitance responsive to a sensed capacitance or a value produced from the sensed capacitance.

25. The capacitive touch-screen device of claim 21, wherein the touch-detection circuit further includes circuits for producing the force signal from a linear or logarithmic interpolation between one and a ratio of the no-touch capacitance and a maximum touch capacitance responsive to a sensed capacitance or a value produced from the sensed capacitance.