Touch Controller Baseline Delta Adjustment for False Touch Reduction
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Solution Overview
Problem
Capacitive touch screens often detect false touches due to unwanted capacitive changes in sensor nodes without actual touch points, leading to inaccurate touch event detection.
Innovation Solution
A touch controller processes digital capacitance values by calculating baseline delta values and adjusting them to generate adjusted sense line data, which helps in reliably detecting touch points by reducing false touch detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitance threshold detection is used to identify touch points, then touch detection sensitivity is improved, but false touch detection increases
Solution Approach 1:
The patent applies dynamics by making the threshold adaptive rather than fixed. The threshold dynamically adjusts based on the minimum baseline delta calculated from sensor nodes along the same sense line. This allows the system to adapt to varying capacitive conditions and eliminate false touches caused by static threshold limitations.
Solution Approach 2:
The patent changes the parameter used for touch detection by introducing baseline delta calculation and adjustment. Instead of using a fixed capacitance threshold, the system calculates the difference between current capacitance values and baseline values, then adjusts the threshold based on the minimum baseline delta. This parameter transformation effectively distinguishes true touches from false touches caused by capacitive coupling.
2Device complexity
If a fixed capacitance threshold is used for touch detection, then the detection process is simple, but accuracy decreases due to capacitive coupling effects
Solution Approach 1:
The patent applies preliminary action by calculating baseline capacitance values and baseline deltas before performing touch detection. The system pre-processes the sensor data to establish reference values that account for capacitive coupling effects, thereby improving detection accuracy without significantly increasing overall system complexity.
Solution Approach 2:
The patent introduces baseline delta as an intermediary parameter between raw capacitance values and touch detection decisions. This intermediary calculation layer compensates for capacitive coupling effects by comparing current readings against adjusted baselines, thereby improving accuracy while maintaining a relatively simple detection framework.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively minimizes false touch detection by adjusting capacitance values relative to no-touch thresholds, enhancing the accuracy of touch point detection on capacitive touch screens.
Implementation Method 1
A typical capacitive touch sensor is formed by an array of conductive force lines Ci and sense lines Lj that are arranged in orthogonal to one another to form a matrix or array of touch or sensor nodes CiLj. The sensor nodes collectively detect the touch information, which includes location information (i.e., which sensor nodes indicate the presence of touch point), the touch event type, along with other parameters like pressure, size, and so on, as will be appreciated by those skilled in the art. The sensor nodes CiLj detect the touch information through variations of four 'fringing' capacitances associated with each sensor node Ci,Lj.
Data Source
AI summary
A touch controller processes a captured data frame and detects the presence of touch points in the data frame. The data frame includes a plurality of digital capacitance values organized as groups of sense line data and the touch controller determines for each digital capacitance value in a group of sense line data the difference between the digital capacitance value and an associated no-touch threshold to generate a baseline delta value for each digital capacitance value in the group. The touch controller selects the minimum baseline delta and adjusts each digital capacitance value in the group by the minimum baseline delta to generate adjusted sense line data. The touch control generates adjusted sense line data for each group of sense line data in the data frame and thereafter processes the groups of adjusted sense line data to detect the presence of touch points in the data frame.