Touch slider-position sensing

• US 10,551,945 B2
• Filed: 03/02/2018
• Issued: 02/04/2020
• Est. Priority Date: 03/02/2017
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Fomin, Evgeny
• Primary Examiner(s): Ritchie, Darlene M
• Application Number:
  US15/911,067
• Publication Number:
  US 20190042053A1
• Time in Patent Office: 704 Days
• CPC Class Codes: G06F 2203/0339 Touch strips, e.g. orthogonal touch strips to control cursor movement or scrolling; single touch strip to adjust parameter or to implement a row of soft keys
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06F 3/03548 Sliders, in which the moving part moves in a plane
• CPC Class Codes: G06F 3/0362 with detection of 1D translations or rotations of an operating part of the device, e.g. scroll wheels, sliders, knobs, rollers or belts
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/04186 Touch location disambiguation
• CPC Class Codes: G06F 3/044 by capacitive means

Abstract

Touch slider-position sensing useable with a capacitive touch sensor that includes multiple capacitive electrodes arranged to define a slider track. The touch slider-position sensing methodology includes: (a) generating a set of calibration vectors for points of the slider track; (b) determining a touch slider-position based on (i) measuring a measurement/data vector associated with the touch-press slider-location, (ii) determining an angle between the measurement/data vector and a subset of the calibration vectors, and (iii) determining touch slider-position based on the angles between the measurement data vectors and the subset of calibration vectors. The method can include performing a quadratic or higher order interpolation of the angles between the measurement/data vector and the subset of the calibration vectors.

Claims

1. A method for touch-position sensing with a capacitive touch sensor that includes multiple capacitive electrodes arranged to define a slider track, comprising:

performing a calibration operation to measure calibration data at points along the slider track, and generating a corresponding set of calibration vectors R(X)=(R₀, R₁, . . . , R_N) for points of the slider track, where R_i is a calibration data response of each capacitive electrode at the points along the slider track, and after the calibration operation, the calibration vectors corresponding to a configuration of the capacitive electrodes;

performing position sensing operations at a defined sensing frequency to determine a touch-position on the slider track based on;

measuring position data for the touch-position, and generating a corresponding touch-position vector D=(D₀, D₁, . . . , D_N), where D_i is a position data response of each capacitive electrode at the touch-position,

determining an angle between the touch-position vector and each of a subset of the calibration vectors;

determining a touch-position based at least in part on the angles between the touch-position vectors and the subset of calibration vectors.

2. The method of claim 1, wherein the calibration operation comprises:

measuring, for each capacitive electrode, zero-level calibration data corresponding to no-touch;

measuring, for each capacitive electrode, touch calibration data at defined L positions on the slider track;

determining L+1 calibration vectors as a difference between the zero-level calibration data and the touch calibration data.

3. The method of claim 1, wherein the calibration operation comprises:

measuring, for each capacitive electrode, calibration data at defined L positions along the slider track;

generating L+1 calibration data sets, corresponding to the L positions and a zero position;

determining L+1 calibration vectors R_i from the L+1 calibration data sets.

4. The method of claim 3, further comprising

post-processing each calibration data set to remove a DC component;

and

generating, from the remaining AC calibration data, the corresponding calibration vector R_j.

5. The method of claim 3, wherein each calibration data set is based on averaging calibration data responses for multiple touches of each slider-position L.

6. The method of claim 5, wherein removing the DC component is based on removing a moving average of calibration data measurements.

7. The method of claim 1, further comprising

subtracting from the position data a DC component;

and

generating, from the remaining AC position data, the corresponding touch-position vector D_j.

8. The method of claim 7, wherein removing a DC component is based on removing a moving average of position data measurements.

9. The method of claim 1, wherein the position sensing operations further comprise:

determining a length of the touch-position vector D_j, and

determining the touch-position based in part on a comparison of the length of the touch-position vector D_i a with a defined threshold value.

10. The method of claim 9, further comprising determining the touch position based on:

determining the cosine between the position vector [D_j] and the calibration vector R_j according to

11. The method of claim 10, further comprising:

performing a quadratic or higher order interpolation of the angles between the position vector and the subset of the calibration vectors.