Capacitive detection systems, modules and methods

• US 20090045822A1
• Filed: 08/13/2007
• Published: 02/19/2009
• Est. Priority Date: 08/13/2007
• Status: Abandoned Application

• Current Assignee: Winbond Electronics Corporation
• Original Assignee: Winbond Electronics Corporation
• Inventors: Tasher, Nir, Nosovitsky, Einat, Lukoyanichev, Mark, Friedman, Yehezkel
• Application Number:
  US11/889,434
• Publication Number:
  US 20090045822A1
• Time in Patent Office: Days
• US Class Current: 324/686
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• 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: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 2217/960705 Safety of capacitive touch and proximity switches, e.g. increasing reliability, fail-safe
• CPC Class Codes: H03K 2217/960715 Rc-timing; e.g. measurement of variation of charge time or discharge time of the sensor

Abstract

Capacitive detection systems, modules, and methods. In one embodiment, time interval measurement(s) are generated that are monotonic functions of the capacitance(s) of capacitive sensor(s) in a capacitive sensing area. In one embodiment, the generated time interval measurement(s), or any other monotonic function(s) of capacitance(s) of capacitive sensor(s) in a capacitive sensing area, may be analyzed to detect the presence of an object near the capacitive sensing area and/or to detect the position of an object near the capacitive sensing area.

Claims

1. A capacitive detection method, comprising:

for at least one capacitive sensor in a capacitive sensing area, receiving data which is a monotonic function of capacitance of said capacitive sensor;

checking whether for at least one of said at least one capacitive sensor, received data or a function thereof has a predetermined relationship with at least one predetermined level; and

if, for at least one of said at least one capacitive sensor, received data or a function thereof has said predetermined relationship with said at least one predetermined level, then detecting that an object is present near said capacitive sensing area.

2. The method of claim 1, wherein said at least one predetermined level includes two predetermined levels, and presence is detected if for at least one of said at least one capacitive sensor received data or a function thereof is between said two predetermined levels.

3. The method of claim 1, wherein said function of said received data equals said received data minus a calibration value for a corresponding sensor or an absolute value thereof, and wherein said calibration value is a data value for said sensor when no object is near said capacitive sensing area.

4. The method of claim 1, wherein said at least one predetermined level depends on at least one characteristic of an input device including said capacitive sensing area.

5. The method of claim 4, wherein said at least one characteristic is selected from a group comprising:

thickness of a covering of said input device and electric properties of a covering of said input device.

6. The method of claim 1, further comprising:

if an object is detected as present, then for each at least one dimension calculating an unfiltered coordinate of said object using for each of at least two sensors said received data or a function thereof to weight a coordinate of said corresponding capacitive sensor.

7. The method of claim 6, further comprising:

for each said at least one dimension, calculating a filtered coordinate by performing a weighted average of said unfiltered coordinate and a previously calculated filtered coordinate.

8. The method of claim 7, wherein said weighted average includes weights at least partially dependent on a characteristic of an input device including said capacitive sensing area.

9. A capacitive detection method, comprising:

receiving data corresponding to two arrays of a plurality of capacitive sensors arranged in two dimensions in a capacitive sensing area, wherein received data corresponding to a sensor is a monotonic function of capacitance of said corresponding sensor;

using said received data to detect presence of an object by determining whether received data or a function thereof corresponding to any of said sensors has a predetermined relationship with at least one predetermined level; and

if presence of an object is detected, then for each array, using received data or a function thereof corresponding to sensors in said array to determine an unfiltered coordinate of said object in a corresponding dimension by performing the following;

selecting which received data or a function thereof corresponding to sensors in said array will be used in determining said unfiltered coordinate; and

calculating said unfiltered coordinate of said object in a weighted average calculation using each said selected received data or a function thereof to weight a coordinate of a corresponding capacitive sensor.

10. The method of claim 9, wherein said selecting includes:

selecting received data or a function thereof which is of highest value and which has a predetermined relationship with at least one predetermined level; and

selecting received data or a function thereof corresponding to at least one sensor located in a first direction away from said highest value sensor and corresponding to at least one sensor located in a second direction away from said highest value sensor.

11. The method of claim 10, wherein said received data or a function thereof corresponding to at least one sensor located in said first direction and corresponding to at least one sensor located in said second direction are above a predetermined level which is at least partly dependent on a characteristic of an input device including said capacitive sensing area or on a noise margin level.

12. The method of claim 9, wherein said at least one predetermined level depends on at least one characteristic of an input device including said capacitive sensing area.

13. The method of claim 9, wherein said function of said received data equals said received data minus a calibration value for a corresponding sensor or an absolute value thereof, wherein said calibration value is a data value for said sensor when no object is present near said capacitive sensing area.

14. The method of claim 9, further comprising:

if presence of an object is detected, then for each array, calculating a filtered coordinate in a corresponding dimension by performing a weighted average of said unfiltered coordinate and a previously calculated filtered coordinate.

15. A controller module for capacitive detection, comprising:

an interaction module configured, for at least one capacitive sensor in a capacitive sensing area, to receive data which is a monotonic function of capacitance of said capacitive sensor; and

a presence detection module configured to check whether for at least one of said at least one capacitive sensor, received data or a function thereof has a predetermined relationship with at least one predetermined level; and

configured to detect that an object is present near said capacitive sensing area if for at least one of said at least one capacitive sensor received data or a function thereof has said predetermined relationship with said at least one predetermined level.

16. The controller module of claim 15, further comprising:

a calibration module configured to apply said function to said received data, wherein said function at least includes subtracting a calibration value corresponding to a sensor from said received data corresponding to said sensor or taking an absolute value of a difference between said received data and a calibration value corresponding to a sensor.

17. The controller module of claim 15, further comprising:

a position detection module configured to determine an unfiltered coordinate of a detected object in at least one dimension by using for each at least two sensors in each dimension said received data or a function thereof to weight a coordinate of said corresponding capacitive sensor.

18. The controller module of claim 17, further comprising:

an offset calculation module configured to calculate a filtered coordinate of said detected object in at least one dimension, by performing for each dimension a weighted average of said unfiltered coordinate in said dimension and a previously calculated filtered coordinate in said dimension.

19. A controller module for capacitive detection, comprising:

an interaction module configured to receive data corresponding to two arrays of a plurality of capacitive sensors arranged in two dimensions in a capacitive sensing area, wherein received data corresponding to a sensor is a monotonic function of capacitance of said corresponding sensor;

a presence detection module configured to use said received data to detect presence of an object by determining whether received data or a function thereof corresponding to any of said sensors has a predetermined relationship with at least one predetermined level; and

a position detection module, configured if presence of an object is detected, then for each array, to use received data or a function thereof corresponding to sensors in said array to determine a coordinate of said object in a corresponding dimension, said position detection module including;

means for selecting which received data or a function thereof corresponding to sensors in said array will be used in determining said unfiltered coordinate; and

means for calculating said unfiltered coordinate of said object in a weighted average calculation using each said selected received data or a function thereof to weight a coordinate of a corresponding capacitive sensor.

20. The controller module of claim 19, further comprising:

a calibration module configured to apply said function to said received data, wherein said function at least includes subtracting a calibration value corresponding to a sensor from said received data corresponding to said sensor or taking an absolute value of a difference between said received data and a calibration value corresponding to a sensor.

21. The controller module of claim 19, further comprising:

an offset calculation module configured for each array, to calculate a filtered coordinate by performing a weighted average of said unfiltered coordinate and a previously calculated filtered coordinate.

22. A capacitive detection computer program product comprising a computer useable medium having computer readable program code embodied therein, the computer program product comprising:

computer readable program code for causing the computer to receive, for at least one capacitive sensor in a capacitive sensing area, data which is a monotonic function of capacitance of said capacitive sensor;

computer readable program code for causing the computer to check whether for at least one of said at least one capacitive sensor, received data or a function thereof has a predetermined relationship with at least one predetermined level; and

computer readable program code for causing the computer to detect that an object is present near said capacitive sensing area if for at least one of said at least one capacitive sensor received data or a function thereof has said predetermined relationship with said at least one predetermined level.

23. A capacitive detection computer program product comprising a computer useable medium having computer readable program code embodied therein, the computer program product comprising:

computer readable program code for causing the computer to receive data corresponding to two arrays of a plurality of capacitive sensors arranged in two dimensions in a capacitive sensing area, wherein received data corresponding to a sensor is a monotonic function of capacitance of said corresponding sensor;

computer readable program code for causing the computer to use said received data to detect presence of an object by determining whether received data or a function thereof corresponding to any of said sensors has a predetermined relationship with at least one predetermined level; and

computer readable program code for causing the computer for each array if presence of an object is detected, to use received data or a function thereof corresponding to sensors in said array to determine an unfiltered coordinate of said object in a corresponding dimension, including computer readable program code for causing the computer to perform the following;

computer readable program code for causing the computer to select which received data or a function thereof corresponding to sensors in said array will be used in determining said unfiltered coordinate; and

computer readable program code for causing the computer to calculate said unfiltered coordinate of said object in a weighted average calculation using each said selected received data or a function thereof to weight a coordinate of a corresponding capacitive sensor.