Passive touch detection for capacitive sense array

Patent metadata

Field	Value
Publication number	US-12124657-B2
Application number	US-202016917437-A
Country	US
Kind code	B2
Filing date	Jun 30, 2020
Priority date	Apr 30, 2014
Publication date	Oct 22, 2024
Grant date	Oct 22, 2024

Abstract

A processing device scans a capacitive sense array to determine a characteristic of a noise signal. A processing device further detects a location of a touch proximate to the capacitive sense array by a passive touch object using a first mode of capacitance touch detection. The first mode of capacitive touch detection uses a capacitive coupling of the noise signal to the capacitive sense array through the passive touch object to detect the touch.

First claim

What is claimed is:

1. A method comprising:
scanning a capacitive sense array to determine a characteristic of a noise signal; and
detecting, by a processing device, a location of a touch proximate to the capacitive sense array by a passive touch object using a first mode of capacitance touch detection that uses a capacitive coupling of the noise signal to the capacitive sense array through the passive touch object to detect the touch, wherein a transmit signal for mutual capacitance measurement is disconnected from the capacitance sense array, yielding a receive signal derived from the noise signal, absent the transmit signal;
wherein detecting the touch proximate to the capacitive sense array by the passive touch object using the first mode of capacitance touch detection further comprises:
comparing a first plurality of signal measurements to a touch threshold, the first plurality of signal measurements being indicative of the capacitive coupling of the noise signal to a first plurality of electrodes through the passive touch object.

2. The method of claim 1 , further comprising:
selecting the first mode of capacitance touch detection from a plurality of modes of capacitance touch detection if the characteristic of the noise signal indicates a presence of the noise signal;
selecting the second mode of capacitance touch detection from the plurality of modes of capacitance touch detection if the characteristic of the noise signal indicates an absence of the noise signal, wherein the second mode of capacitance touch detection couples the transmit signal to at least a portion of the capacitance sense array; and
detecting, by the processing device in view of the characteristic of the noise signal, a touch proximate to the capacitive sense array by a passive touch object using the first mode of capacitance touch detection or the second mode of capacitance touch detection.

3. The method of claim 2 , wherein detecting the touch proximate to the capacitive sense array by a passive touch object using the second mode of capacitance scanning, during a third operation, a first plurality of electrodes along a first axis of the capacitive sense array to determine a third plurality of signal measurements corresponding to a mutual capacitance at electrode intersections of the capacitive sense array;
scanning, during a fourth operation, a second plurality of electrodes along a second axis of the capacitive sense array to determine a fourth plurality of signal measurements corresponding to the mutual capacitance at electrode intersections of the capacitive sense array, wherein the third operation and the fourth operation occur at a different window of time;
identifying a touch position equation from a plurality of touch position equations for use in determining a third coordinate and a fourth coordinate of the touch by the passive touch object proximate to the capacitive sense array; and
determining the third coordinate in view of the third plurality of signal measurements and the fourth coordinate in view of the fourth plurality of signal measurements.

4. The method of claim 1 , further comprising:
selecting the first mode and a second mode of capacitance touch detection from a plurality of modes of capacitance touch detection if the characteristic of the noise signal indicates a presence of the noise signal;
rejecting signal measurements of the second mode of capacitance touch detection indicating the touch, in view of signal measurements of the first mode of capacitance touch detection indicating a non-touch; and
detecting the touch proximate to the capacitive sense array by the passive touch object using the second mode of capacitance touch detection.

5. The method of claim 1 , wherein the passive touch object is a part of a human body.

6. The method of claim 1 , wherein detecting the touch proximate to the capacitive sense array by the passive touch object using the first mode of capacitance touch detection, further comprises:
scanning, during a first operation, a first plurality of electrodes along a first axis of the capacitive sense array to determine a first plurality of signal measurements indicative of the capacitive coupling of the noise signal to the first plurality of electrodes through the passive touch object; and
determining a first coordinate of the touch by the passive touch object proximate to the capacitive sense array in view of the first plurality of signal measurements.

7. The method of claim 6 , wherein scanning the first plurality of electrodes comprises:
configuring a second plurality of electrodes along a second axis to a ground potential; and determining, at the first plurality of electrodes along the first axis, the first plurality of signal measurements corresponding to the capacitive coupling of the noise signal to the first plurality of electrodes through the passive touch object.

8. The method of claim 6 , wherein detecting the touch proximate to the capacitive sense array by the passive touch object using the first mode of capacitance touch detection, further comprises:
scanning, during a second operation, a second plurality of electrodes along a second axis of the capacitive sense array to determine a second plurality of signal measurements indicative of the capacitive coupling of the noise signal to the second plurality of electrodes through the passive touch object;
comparing the second plurality of signal measurements to a touch threshold; and
determining a second coordinate of the touch by the passive touch object proximate to the capacitive sense array in view of the second plurality of signal measurements.

9. The method of claim 8 , wherein scanning the second plurality of electrodes comprises:
configuring the first plurality of electrodes along the first axis to a ground potential; and
determining, at the second plurality of electrodes along the second axis, the second plurality of signal measurements corresponding to the capacitive coupling of the noise signal to the second plurality of electrodes through the passive touch object.

10. An apparatus comprising:
a capacitive sense array; and
a processing device configured to:
scan the capacitive sense array to determine a characteristic of a noise signal; and
detect a location of a touch proximate to the capacitive sense array by a passive touch object using a first mode of capacitance touch detection that uses a capacitive coupling of the noise signal to the capacitive sense array through the passive touch object to detect the touch,
wherein to detect the touch proximate to the capacitive sense array by the passive touch object using the first mode of capacitance touch detection,
wherein a transmit signal for a second mode of capacitance touch detection is disconnected from the capacitance sense array, yielding a receive signal derived from the noise signal, absent the transmit signal,

compare a first plurality of signal measurements to a touch threshold, the first plurality of signal measurements being indicative of the capacitive coupling of the noise signal to a first plurality of electrodes through the passive touch object.

11. The apparatus of claim 10 , the processing device further configured to:
select the first mode of capacitance touch detection from a plurality of modes of capacitance touch detection if the characteristic of the noise signal indicates a presence of the noise signal;
select the second mode of capacitance touch detection from the plurality of modes of capacitance touch detection if the characteristic of the noise signal indicates an absence of the noise signal, wherein the second mode of capacitance touch detection couples the transmit signal to at least a port

Assignees

• Cypress Semiconductor Corp

Inventors

• Maharyta Andriy
• Karpin Oleksandr
• Klein Hans

Classifications

• G06F3/0446

  using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes · CPC title

• G06F3/044 Primary

  by capacitive means · CPC title

• G06F3/04166 Primary

  Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving (Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184) · CPC title