Electronic device

Patent metadata

Field	Value
Publication number	US-10372283-B2
Application number	US-201815872980-A
Country	US
Kind code	B2
Filing date	Jan 16, 2018
Priority date	Jan 16, 2017
Publication date	Aug 6, 2019
Grant date	Aug 6, 2019

Abstract

According to a first aspect of the present disclosure, an electronic device for use in a touch-based user interface is provided, the electronic device comprising a first capacitor, a second capacitor, a third capacitor, and an analog-to-digital converter, wherein: the first capacitor and the second capacitor are switchably coupled to each other; the first capacitor is switchably coupled to an input of the analog-to-digital converter; the second capacitor is coupled to the input of the analog-to-digital converter; the third capacitor is coupled to the first capacitor; the third capacitor is switchably coupled to the second capacitor; the third capacitor is switchably coupled to the input of the analog-to-digital converter. According to a second aspect of the present disclosure, a corresponding method of manufacturing an electronic device for use in a touch-based user interface is conceived.

First claim

The invention claimed is:

1. An electronic device for use in a touch-based user interface, the electronic device comprising a set of first capacitors, a second capacitor, a third capacitor, and an analog-to-digital converter, wherein:
the set of first capacitors and the second capacitor each have a first terminal that are coupled to each other through a set of first switches;
the first terminal of each capacitor of the set of first capacitors is coupled to an input of the analog-to-digital converter through a first switch of the set of first switches, the first terminal of each of the first capacitors is coupled to a voltage input terminal through a second switch, a second terminal of each of the first capacitors is coupled to the voltage input terminal through a third switch, and the second terminal of each of the first capacitors is coupled to a voltage reference terminal through a fourth switch, and wherein the set of first capacitors are sensing capacitors and each capacitor of the set of first capacitors corresponds to a position in an array of sensing elements which represent a multi-channel touch sensor;
the first terminal of the second capacitor is coupled to the input of the analog-to-digital converter, and a second terminal of the second capacitor is coupled to the voltage reference terminal;
a first terminal of the third capacitor is coupled to the first terminal of each of the first capacitor, and a second terminal of the third capacitor is coupled to the voltage reference terminal;
the third capacitor is coupled to the second capacitor through the first switch;
the third capacitor is coupled to the input of the analog-to-digital converter through the first switch.

2. The electronic device of claim 1 , wherein the third capacitor is implemented as a printed circuit board capacitor made from neighboring tracks on the printed circuit board.

3. The electronic device of claim 1 , being configured to derive individual capacitances on the first capacitors from partial sum values, wherein said partial sum values are obtained by measuring and adding together combined capacitances on subsets of the set of first capacitors.

4. The electronic device of claim 3 , further being configured to measure capacitances on mutually different subsets of the set of first capacitors.

5. The electronic device of claim 3 , further being configured to apply a weighting factor to the partial sum values.

6. The electronic device of claim 5 , further being configured to regroup the weighted partial sum values, thereby yielding high-pass filter terms.

7. The electronic device of claim 3 , further being configured to filter the partial sum values.

8. The electronic device of claim 7 , further being configured to use an infinite-impulse-response filter for filtering the partial sum values.

9. The electronic device of claim 1 , wherein the first capacitors are coupled to general-purpose input/output pins.

10. The electronic device of claim 9 , wherein the general-purpose input/output pins, the analog-to-digital converter and the second capacitor form part of a microcontroller unit.

11. A smart card comprising the electronic device of claim 1 .

12. A method of manufacturing an electronic device for use in a touch-based user interface, the method comprising providing the electronic device with a first capacitor, a second capacitor, a third capacitor, and an analog-to-digital converter, wherein:
the set of first capacitors and the second capacitor each have a first terminal that are coupled to each other through a first switch;
the first terminal of each capacitor of the set of first capacitors is coupled to an input of the analog-to-digital converter through the first switch, the first terminal of each of the first capacitors is coupled to a voltage input terminal through a second switch, a second terminal of each of the first capacitors is coupled to the voltage input terminal through a third switch, and the second terminal of each of the first capacitors is coupled to a voltage reference terminal through a fourth switch;
the first terminal of the second capacitor is coupled to the input of the analog-to-digital converter, and a second terminal of the second capacitor is coupled to the voltage reference terminal;
a first terminal of the third capacitor is coupled to the first terminal of the first capacitor, and a second terminal of the third capacitor is coupled to the voltage reference terminal;
the third capacitor is coupled to the second capacitor through the first switch;
the third capacitor is coupled to the input of the analog-to-digital converter through the first switch.

Assignees

• Nxp Bv

Inventors

• Suwald Thomas

Classifications

• G06F2203/04103

  Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices · CPC title

• G06F3/0416

  Control or interface arrangements specially adapted for digitisers · CPC title

• H03K2217/96074

  Switched capacitor · CPC title

• G06F3/044 Primary

  by capacitive means · CPC title

• H03K17/9622

  using a plurality of detectors, e.g. keyboard · CPC title