CAPACITIVE TOUCH SENSORS

• US 20100096193A1
• Filed: 07/10/2009
• Published: 04/22/2010
• Est. Priority Date: 10/22/2008
• Status: Active Grant

• Current Assignee: Neodrón Limited (Atlantic IP Services Limited)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Sleeman, Peter, Yilmaz, Esat
• Granted Patent: US 8,610,009 B2
• Time in Patent Office: Days
• US Class Current: 178/18.06
• 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 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03M 11/20 Dynamic coding, i.e. by key scanning H03M11/26 takes precedence

Abstract

A touch data set is acquired via signals from each sensing node in a capacitive sensor array having a plurality of sensing nodes. Touch presence and location on the capacitive sensor array is determined from the touch data set. In subsequent sampling periods while presence of a touch continues to be detected, touch data sets may be acquired from respective subsets of the sensing nodes, each subset being located at and adjacent to the touch location determined in the preceding sampling period.

Claims

1. A method comprising:

acquiring a touch data set with signals from each sensing node in a capacitive sensor array having a plurality of sensing nodes;

determining touch presence and location on the capacitive sensor array from the touch data set; and

in subsequent sampling periods while presence of a touch continues to be detected acquiring touch data sets from respective subsets of the sensing nodes, each subset being located at and adjacent to the touch location determined in the preceding sampling period.

2. The method of claim 1, wherein the capacitive sensor array has a two-dimensional array of sensing nodes comprising a plurality of first lines and a plurality of second lines, and wherein the subsets of the sensing nodes involve a subset of the first lines.

3. The method of claim 2, wherein the subsets of the sensing nodes additionally involve a subset of the second lines.

4. The method of claim 2, wherein the sensing nodes are formed by coupling capacitances between respective ones of the first and second lines, the first lines being driven and the second lines being connected to at least one charge measurement capacitor for measuring the coupling capacitances.

5. The method of claim 1, wherein the capacitive sensor array is a one-dimensional array of sensing nodes.

6. The method of claim 1, wherein the subset is restricted to the sensing node at which the touch has been determined to be present and immediately adjacent sensing nodes in at least one dimension.

7. The method of claim 1, wherein acquiring touch data sets from respective subsets of the sensing nodes comprises acquiring a touch data set with signals from each sensing node when presence of a touch is absent in a subsequent sampling period.

8. A capacitive sensor device, comprising:

a capacitive sensor array having a plurality of sensing nodes;

a controller operable to acquire touch data from each of the sensing nodes and to detect presence and location of a touch from the touch data;

wherein the controller is operable to acquire sets of touch data in a succession of sampling periods such that touch data sets are acquired that include signals from each of the sensing nodes when the presence of a touch is absent in a preceding sample period; and

wherein the controller is operable to acquire touch data sets limited to a subset of the sensing nodes when presence of a touch is detected in a preceding sampling period, with each subset being located at and adjacent to the touch location determined in the preceding sampling period.

9. The device of claim 8, wherein the capacitive sensor array has a two-dimensional array of sensing nodes comprising a plurality of first lines and a plurality of second lines, and wherein the subsets of the sensing nodes involve a subset of the first lines.

10. The device of claim 9, wherein the subsets of the sensing nodes additionally involve a subset of the second lines.

11. The device of claim 9, wherein the sensing nodes are formed by coupling capacitances between respective ones of the first and second lines, the controller being connected to drive the first lines and to measure capacitance of at least one charge measurement capacitor connected to the second lines in order to measuring the coupling capacitances.

12. The device of claim 8, wherein the capacitive sensor array is a one-dimensional array of sensing nodes.