Touch Sensor Retransmission Compensation via Outer Product
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Solution Overview
Problem
Retransmission effects in touch sensors cause inaccurate touch position estimation, reduce touch amplitude, and can result in the interpretation of single touches as multiple touches or the complete disappearance of touches, leading to reduced accuracy and reliability in capacitive touch sensing systems.
Innovation Solution
A method is introduced where the touch-sensor controller generates a first matrix of mutual capacitance measurements and estimates retransmission by calculating a second vector of self-capacitance measurements, then calculates an outer product to adjust the first matrix, thereby compensating for retransmission effects and improving touch input indication accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If retransmission effects are present in the touch sensor, then the touch sensor can detect touch input, but the touch position estimation accuracy is reduced and touch amplitude is reduced
Solution Approach 1:
The patent applies feedback by using self-capacitance measurements to detect retransmission effects and then using this information to correct mutual capacitance measurements. The controller continuously monitors for retransmission and adjusts the touch input indication accordingly, creating a closed-loop system that improves measurement accuracy while maintaining reliable touch detection.
Solution Approach 2:
The patent uses self-capacitance measurements as an intermediary to detect and quantify retransmission effects. These self-capacitance measurements serve as a mediator that provides information about the presence and magnitude of retransmission, which is then used to correct the primary mutual capacitance measurements without directly interfering with the touch detection process.
2Ease of operation
If retransmission effects occur, then touch input can be detected, but single touches may be interpreted as multiple touches or disappear completely
Solution Approach 1:
The controller uses feedback from self-capacitance measurements to identify when retransmission is occurring and applies corrections to prevent incorrect touch interpretation. This feedback mechanism ensures that single touches are not misinterpreted as multiple touches or lost entirely, maintaining accurate touch input detection.
Solution Approach 2:
The patent converts the harmful retransmission effect into a beneficial signal by using the self-capacitance measurements (which detect the retransmission) as the basis for correction. The retransmission itself provides information about its own presence and magnitude, which is then used to eliminate its harmful effects on touch interpretation.
3Productivity
If retransmission effects are present, then capacitance measurements can be taken, but touch amplitude measurement reliability is reduced
Solution Approach 1:
Self-capacitance measurements serve as an intermediary that provides information about retransmission effects without replacing the primary mutual capacitance measurements. This intermediary data is used to correct the mutual capacitance measurements, preserving the ability to take capacitance measurements while improving touch amplitude measurement reliability.
Solution Approach 2:
The system uses feedback from self-capacitance measurements to continuously monitor and correct mutual capacitance measurements. This feedback loop ensures that touch amplitude measurements remain reliable even in the presence of retransmission effects, maintaining measurement capability while improving accuracy.
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
This approach enhances touch position estimation accuracy, increases touch amplitude measurement reliability, and reduces the likelihood of incorrect touch interpretation, ensuring more precise detection of touch events.
Implementation Method 1
When an object touches or comes within proximity of the surface of the capacitive touch screen, a change in capacitance may occur within the touch screen at the location of the touch or proximity.
Data Source
AI summary
In one embodiment, a method of compensating for retransmission effects in a touch sensor includes, in response to measuring a touch input on a display, generating a first matrix comprising a plurality of first measurements associated with a plurality of capacitive nodes of a touch sensor. The method also includes estimating an amount of retransmission associated with the touch input by generating a first vector comprising one or more second measurements associated with one or more first electrode lines of the touch sensor, generating a second vector comprising one or more third measurements associated with one or more second electrode lines of the touch sensor, and calculating an outer product of the first and second vectors. The method includes generating a revised indication of the touch input based on the first matrix and the estimated amount of retransmission.