Granted Patent B2

US 9,939,964 · App. 13/402,981 · Granted Apr 10, 2018

Abstract

Claims (27)

1. An apparatus for providing a scan signal to a plurality of electrode elements of a touch panel, comprising:

a capacitive sensing module that selectively provides the scan signal at a first selected single scan frequency, the scan signal provided as a continuous stream of pulses at the first selected single scan frequency, the capacitive sensing module including oscillator circuitry that generates an oscillating scan signal at a fundamental frequency;

a plurality of resistor and/or capacitor elements that are each selectively connectable to the oscillator circuitry to provide a respective signal having a respective scan frequency; and

a noise detection module that determines if a noise level at the first selected single scan frequency satisfies a pre-determined condition; and

wherein:

the capacitive sensing module provides the scan signal at a second single scan frequency when the noise level on the first selected single scan frequency satisfies the pre-determined condition, and the pre-determined condition is satisfied when too many scan/return lines that exhibit characteristics of valid touches are detected that exceed a particular threshold value necessitating a change to a different single scan frequency; and

the capacitive sensing module and noise detection module operate, respectively, to selectively provide the scan signals and determine noise levels while the apparatus is in a non-test, operational state.

2. The apparatus as claimed in claim 1 , wherein the oscillating scan signal is a square wave signal.

3. The apparatus as claimed in claim 1 , further comprising:

a touch panel comprising a plurality of conductive elements; and

multiplexer circuitry that selectively connects the scan signal to the conductive elements in a pre-determined order.

4. The apparatus as claimed in claim 1 , further comprising:

the noise detection module determines if more than a pre-determined number of touch instances are indicated to thereby indicate that a further scan frequency is to be selected.

5. An automated teller machine (ATM) comprising the apparatus as claimed in claim 1 .

6. A method of providing a scan signal to a plurality of electrode elements of a touch panel while the touch panel is in a non-test, operational state, the method comprising:

providing a scan signal at a first selected single of a plurality of possible scan frequencies to a plurality of electrode elements of a touch panel, the scan signal provided as a continuous stream of pulses at the first selected single scan frequency;

determining if a noise level at the first selected single scan frequency satisfies a pre-determined condition;

providing a scan signal at a second single scan frequency to the plurality of electrode elements when the detected noise level on the first selected single scan frequency satisfies a pre-determined condition and the pre-determined condition is satisfied when too many scan/return lines that exhibit characteristics of valid touches are detected that exceed a particular threshold value necessitating a change to a different single scan frequency;

generating a scan signal having a fundamental frequency; and

selectively connecting an RC component to oscillator circuitry to vary the fundamental frequency of the scan signal.

7. The method as claimed in claim 6 , further comprising

determining a number of touch instances on the touch panel; and

if said number is greater than a pre-determined number, determining that the noise level satisfies a pre-determined condition.

8. The method as claimed in claim 7 , further comprising:

determining a touch instance by determining a change in period of a detected signal of a plurality of the electrode elements in a region of the touch panel.

9. The method as claimed in claim 6 , further comprising:

selectively connecting the scan signal to the electrode element in a pre-determined order.

Assignments (10)