Capacitance Scanning Proximity Detection

• US 20120044199A1
• Filed: 07/14/2011
• Published: 02/23/2012
• Est. Priority Date: 08/23/2010
• Status: Active Grant

• Current Assignee: Parade Technologies, Ltd.
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Maharyta, Andriy, Ryshtun, Andriy, Kremin, Victor, Hutnyk, Volodymyr, Karpin, Oleksadr
• Granted Patent: US 9,250,752 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 2203/04108 Touchless 2D- 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 without distance measurement in the Z direction
• CPC Class Codes: G06F 3/041662 using alternate mutual and self-capacitive scanning
• 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

Abstract

A method and apparatus for scanning a first set of electrodes of a capacitive sense array using a first sensing mode to identify a presence of an object in proximity to the capacitive sense array, where scanning using the first sensing mode identifies objects not in physical contact with the capacitive sense array. The first set of electrodes is scanned using a second sensing mode to determine a location of the object in relation to the capacitive sense array, where rescanning using the second sensing mode determines locations of objects in physical contact with the capacitive sense array.

Claims

1. A method, comprising:

scanning, by a processing device, a first set of electrodes of a capacitive sense array using a first sensing mode to identify a presence of an object in proximity to the capacitive sense array, wherein scanning using the first sensing mode identifies objects not in physical contact with the capacitive sense array; and

scanning the first set of electrodes using a second sensing mode to determine a location of the object in relation to the capacitive sense array, wherein rescanning using the second sensing mode determines locations of objects in physical contact with the capacitive sense array.

2. The method of claim 1, further comprising:

scanning a first electrode of a capacitive sense array using the first sensing mode to generate a first signal, the capacitive sense array comprising a plurality of electrodes;

scanning a second electrode of the capacitive sense array using the first sensing mode to generate a second signal; and

identifying the presence of the object in proximity to the capacitive sense array based on the first signal and the second signal.

3. The method of claim 2, further comprising:

driving a third electrode and a fourth electrode of the capacitive sense array with a shield signal while scanning the first electrode and the second electrode.

4. The method of claim 3, wherein the first electrode, the second electrode, the third electrode and the fourth electrode comprise edge electrodes of the capacitive sense array.

5. The method of claim 2, further comprising:

scanning the first electrode of the capacitive sense array using the second sensing mode to generate a third signal;

scanning the second electrode of the capacitive sense array using the second sensing mode to generate a fourth signal; and

determining a location of the object in relation to the capacitive sense array based on the third signal and the fourth signal, wherein the object is in physical contact with the capacitive sense array.

6. The method of claim 5, further comprising:

scanning the first electrode of the capacitive sense array using a third sensing mode to generate a fifth signal;

scanning the second electrode of the capacitive sense array using the third sensing mode to generate a sixth signal; and

determining a location of the object in relation to the capacitive sense array based on the fifth signal and the sixth signal, wherein the object is not in physical contact with the capacitive sense array.

7. The method of claim 6, wherein the first sensing mode comprises a self-capacitance single electrode mode, wherein the second sending mode comprises a mutual capacitance sensing mode, and wherein the third sensing mode comprises a hybrid mutual-self capacitance single electrode mode.

8. The method of claim 2, further comprising:

measuring a baseline capacitance value for each of the plurality of electrodes in the capacitive sense array.

9. The method of claim 8, wherein identifying a presence of an object in proximity to the capacitive sense array comprises:

comparing the first and second signals the baseline capacitance value for the first electrode and the second electrode to determine a differential value; and

determining if the differential value is greater than a proximity threshold value.

10. An apparatus, comprising:

a capacitive sense array having a plurality of electrodes; and

a processing device coupled to the capacitive sensing array, the processing device configured to;

scan a first set of electrodes of a capacitive sense array using a first sensing mode to identify a presence of an object in proximity to the capacitive sense array, wherein scanning using the first sensing mode identifies objects not in physical contact with the capacitive sense array; and

scan the first set of electrodes using a second sensing mode to determine a location of the object in relation to the capacitive sense array, wherein rescanning using the second sensing mode determines locations of objects in physical contact with the capacitive sense array.

11. The apparatus of claim 10, wherein the processing device is further configured to:

scan a first electrode of the plurality of electrodes using the first sensing mode to generate a first signal;

scan a second electrode of the of the plurality of electrodes using the first sensing mode to generate a second signal; and

identify the presence of the object in proximity to the capacitive sense array based on the first signal and the second signal.

12. The apparatus of claim 11, wherein the processing device is further configured to:

drive a third electrode and a fourth electrode of the plurality of electrodes with a shield signal while scanning the first electrode and the second electrode.

13. The apparatus of claim 12, wherein the first electrode, the second electrode, the third electrode and the fourth electrode comprise edge electrodes of the capacitive sense array.

14. The apparatus of claim 12, wherein the first electrode, the second electrode, the third electrode and the fourth electrode comprise discrete electrodes adjacent to the capacitive sense array.

15. The apparatus of claim 11, wherein the processing device is further configured to:

scan the first electrode of the plurality of electrodes using the second sensing mode to generate a third signal;

scan the second electrode of the plurality of electrodes using the second sensing mode to generate a fourth signal; and

determine a location of the object in relation to the capacitive sense array based on the third signal and the fourth signal, wherein the object is in physical contact with the capacitive sense array.

16. The apparatus of claim 15, wherein the processing device is further configured to:

scan the first electrode of the plurality of electrodes using a third sensing mode to generate a fifth signal;

scan the second electrode of the plurality of electrodes using the third sensing mode to generate a sixth signal; and

determine a location of the object in relation to the capacitive sense array based on the fifth signal and the sixth signal, wherein the object is not in physical contact with the capacitive sense array.

17. The apparatus of claim 16, wherein the first sensing mode comprises a self-capacitance single electrode mode, wherein the second sending mode comprises a mutual capacitance sensing mode, and wherein the third sensing mode comprises a hybrid mutual-self capacitance single electrode mode.

18. The apparatus of claim 11, wherein the processing device is further configured to:

measure a baseline capacitance value for each of the plurality of electrodes in the capacitive sense array.

19. The apparatus of claim 18, wherein when the processing device identifies a presence of an object in proximity to the capacitive sense array, the processing device is configured to:

compare the first and second signals the baseline capacitance value for the first electrode and the second electrode to determine a differential value; and

determine if the differential value is greater than a proximity threshold value.

20. An apparatus comprising:

a capacitive sense array having a plurality of electrodes;

means for identifying a presence of an object in proximity to the capacitive sense array using a first sensing mode, wherein the first sensing mode identifies objects not in physical contact with the capacitive sense array; and

means for determining a location of the object in relation to the capacitance sensing using a second sensing mode, wherein the second sensing mode determines locations of objects in physical contact with the capacitive sense array.

21. The apparatus of claim 20, further comprising:

means for determining a location of the object in relation to the capacitance sensing using a third sensing mode, wherein the object is not in physical contact with the capacitive sense array.

22. The apparatus of claim 21, wherein the first sensing mode comprises a self-capacitance single electrode mode, wherein the second sensing mode comprises a mutual capacitance sensing mode, and wherein the third sensing mode comprises a hybrid mutual-self capacitance single electrode mode.