Capacitance Scanning Proximity Detection

• US 20140035871A1
• Filed: 10/02/2013
• Published: 02/06/2014
• Est. Priority Date: 08/23/2010
• Status: Active Grant

• Current Assignee: Parade Technologies, Ltd.
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Karpin, Oleksandr, Maharyta, Andriy, Ryshtun, Andriy, Kremin, Victor, Hutnyk, Volodymyr
• Granted Patent: US 9,019,226 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 for detecting a object on a capacitance sensing array, the method comprising:

in a first mode;

configuring a capacitance sensing circuit to measure self capacitance,

measuring a first self capacitance of a first electrode,

measuring a second self capacitance of a second electrode,

configuring the capacitance sensing circuit to measure mutual capacitance;

transmitting a transmit (TX) signal on the first electrode;

receiving a receive (RX) signal on the second electrode, the RX signal responsive to a mutual capacitance between the first and second electrode; and

calculating a position of a object proximate to a substrate intermediate to a object and the first and second electrodes; and

in a second mode;

configuring the capacitance sensing circuit to measure mutual capacitance;

transmitting a transmit (TX) signal on the first electrode;

receiving a receive (RX) signal on the second electrode, the RX signal responsive to a mutual capacitance between the first and second electrode; and

calculating a position of the object in physical contact with the substrate intermediate to the object and the first and second electrodes.

2. The method of claim 1, wherein the calculating the position of the object in the first mode applies when the object is proximate to and not in physical contact with the substrate.

3. The method of claim 1, wherein the first and second electrodes are disposed along the periphery of the capacitance sensing array.

4. The method of claim 1 further comprising, in the first mode, measuring a self capacitance of a plurality of addition electrodes representative of the entire capacitance sensing array.

5. The method of claim 1, further comprising, in the first mode, repeating the mutual capacitance measurement between a plurality of additional electrodes representative of the entire capacitance sensing array.

6. The method of claim 1, wherein the first and second electrodes are substantially perpendicular to each other.

7. The method of claim 5, wherein, in the second mode, the mutual capacitance measurement between the first and second electrodes is repeated for each intersection between the first and second electrodes.

8. The method of claim 1, further comprising:

outputting the calculated position of the object proximate to a substrate intermediate to a conductive object and the first and second electrodes as a hover position

outputting the calculated position of the object in physical contact with the substrate intermediate to the conductive object and the first and second electrodes as a touch position.

9. A method for detecting a object with a capacitance sensing array, the method comprising:

when the object is proximate to but not in contact with a substrate intermediate to the sensing array and the object;

measuring a change in self capacitance from the object on a plurality of capacitance sensing electrodes of the capacitance sensing array, and

measuring a change in mutual capacitance from the object between the plurality of capacitance sensing electrodes of the capacitance sensing array, and

calculating the position of the object over the capacitance sensing array from the measured self capacitance and mutual capacitance; and

when the conductive object is in contact with the substrate intermediate to the sensing array and the object;

measuring a change in mutual capacitance from the object between the plurality of capacitance sensing electrodes of the capacitance sensing array, and

calculating the position of the object on capacitance sensing array from the measured mutual capacitance.

10. The method of claim 9, wherein the first and second electrodes are disposed along the periphery of the capacitance sensing array.

11. The method of claim 9 further comprising, when the object is proximate to but not in contact with a substrate intermediate to the sensing array and the object, measuring a change in self capacitance from the object on an additional plurality of capacitance sensing electrodes representative of the capacitance sensing array.

12. The method of claim 9 further comprising, when the conductive object is in contact with the substrate intermediate to the sensing array and the object, measuring the mutual capacitance a plurality of additional electrodes representative of the entire capacitance sensing array.

13. The method of claim 9, wherein the first and second electrodes are substantially perpendicular to each other.

14. The method of claim 13, wherein, when the object is in contact with the substrate, the mutual capacitance measurement between the first and second electrodes is repeated for each intersection between the first and second electrodes.

15. The method of claim 9, further comprising:

outputting the calculated position of the object proximate to a substrate intermediate to the object and the first and second electrodes as a hover position

outputting the calculated position of the object in physical contact with the substrate intermediate to the object and the first and second electrodes as a touch position.

16. A capacitance sensing device configurable to detect a presence of a object proximate to a substrate disposed over an array of capacitance sensing electrodes and to detect a presence of the object in contact with the substrate, the capacitance sensing device comprising:

a capacitance measurement circuit configured to;

measure a self capacitance of the plurality of electrodes, and

measure a mutual capacitance between at least two of the plurality of electrodes; and

processing logic configured to;

calculate a first position of the object based on the self capacitance and mutual capacitance of the plurality of electrodes when the object is proximate to the substrate, and

calculate a second position of the object based on the mutual capacitance between at least two of the plurality of electrodes when the object is in contact with the substrate.

17. The capacitance sensing device of claim 16, wherein:

the first position is communicated to a host as a hover; and

the second position is communicated to the host as a touch.

18. The capacitance sensing device of claim 16, wherein the array of capacitance sensing electrodes is disposed over a display.

19. The capacitance sensing device of claim 16, wherein capacitance measurement circuit is configured to:

drive a transmit (TX) signal on a first electrode; and

receive a receive (RX) signal on a second electrode substantially perpendicular and capacitively coupled to the first electrode, the RX signal representative of the mutual capacitance between the first and second electrodes.

20. The capacitance sensing device of claim 16, wherein self capacitance is measured for a plurality of electrodes representative of the entire capacitance sensing array.