Capacitive sensing with high pass filtering for segmantation

Patent metadata

Field	Value
Publication number	US-2017277293-A1
Application number	US-201615083184-A
Country	US
Kind code	A1
Filing date	Mar 28, 2016
Priority date	Mar 28, 2016
Publication date	Sep 28, 2017
Grant date	—

Abstract

Embodiments described herein include a method for using multiple filtered images. The method includes acquiring changes of capacitance in a sensing region at a plurality of sensor electrodes in a capacitive sensor. The method also includes generating a capacitive frame based on the changes of capacitance and calculating one or more filtered capacitive frames by modifying the capacitive frame with a spatial filter. The method also includes performing clump detection on the one or more filtered capacitive frames, where clump detection includes detecting locations in each filtered capacitive frame exceeding a first threshold near locations that exceed a second threshold in the corresponding capacitive frame.

First claim

What is claimed is:

1 . A method for using multiple filtered images, comprising:
acquiring changes of capacitance in a sensing region at a plurality of sensor electrodes in a capacitive sensor; generating a capacitive frame based on the changes of capacitance; calculating one or more filtered capacitive frames by modifying the capacitive frame, wherein at least one filtered capacitive frame is modified with a high pass spatial filter; and performing clump detection on the one or more filtered capacitive frames, clump detection comprising detecting locations in each filtered capacitive frame exceeding a first threshold near locations that exceed a second threshold in the corresponding capacitive frame.

2 . The method of claim 1 , wherein the changes of capacitance are acquired with transcapacitive sensing and the capacitive frames are two-dimensional images.

3 . The method of claim 1 , wherein the changes of capacitance are acquired with absolute capacitive sensing and the capacitive frames are profiles.

4 . The method of claim 1 , further comprising calculating low frequency noise by comparing two or more filtered capacitive frames.

5 . The method of claim 1 , further comprising calculating low frequency noise by comparing the capacitive frame to one or more filtered capacitive frames.

6 . The method of claim 1 , further comprising determining a bending amount of the capacitive sensor based on comparing two capacitive frames.

7 . The method of claim 1 , wherein the high pass spatial filter comprises a first order derivative for an edge pixel of a capacitive sensor.

8 . The method of claim 1 , wherein the high pass spatial filter comprises a third order derivative for a non-edge pixel of a capacitive sensor.

9 . An input device, comprising:
a plurality of capacitive sensing electrodes configured to receive a signal; and a processing system coupled to the plurality of capacitive sensing electrodes, the processing system comprising:
a filter configured to modify a capacitive frame by calculating one or more filtered capacitive frames corresponding to the capacitive frame;
a segmentation module configured to detect locations in each filtered capacitive frame exceeding a first threshold near locations that exceed a second threshold in the corresponding capacitive frame; and
a classifier configured to classify one or more detected locations in the filtered capacitive frames.

10 . The input device of claim 9 , wherein the filter is a high pass spatial filter.

11 . The input device of claim 10 , wherein the high pass spatial filter comprises a first order derivative for an edge pixel of a capacitive sensor.

12 . The input device of claim 10 , wherein the high pass spatial filter comprises a third order derivative for a non-edge pixel of a capacitive sensor.

13 . The input device of claim 9 , wherein the capacitive sensing electrodes acquire changes of capacitance with transcapacitive sensing and the capacitive frame is a two-dimensional image.

14 . The input device of claim 9 , wherein the capacitive sensing electrodes acquire changes of capacitance with absolute capacitive sensing and the capacitive frame is a profile.

15 . A processing system for capacitive sensing, comprising:
a filter configured to modify a capacitive frame by calculating one or more filtered capacitive frames corresponding to the capacitive frame; a segmentation module configured to detect locations in each filtered capacitive frame exceeding a first threshold near locations that exceed a second threshold in the corresponding capacitive frame; and a classifier configured to classify one or more detected locations in the filtered capacitive frames.

16 . The processing system of claim 15 , wherein the filter is a high pass spatial filter.

17 . The processing system of claim 16 , wherein the high pass spatial filter comprises a first order derivative for an edge pixel of a capacitive sensor.

18 . The processing system of claim 16 , wherein the high pass spatial filter comprises a third order derivative for a non-edge pixel of a capacitive sensor.

19 . The processing system of claim 15 , wherein capacitive sensing electrodes acquire changes of capacitance with transcapacitive sensing and the capacitive frame is a two-dimensional image.

20 . The processing system of claim 15 , wherein capacitive sensing electrodes acquire changes of capacitance with absolute capacitive sensing and the capacitive frame is a profile.

Assignees

• Synaptics Inc

Inventors

• Ling Yi
• Mani Sanjay

Classifications

• G06F3/044 Primary

  by capacitive means · CPC title

• G06F3/0416

  Control or interface arrangements specially adapted for digitisers · CPC title

• G06F3/0446

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

• G06F3/0418 Primary

  for error correction or compensation, e.g. based on parallax, calibration or alignment · CPC title