Projected Capacitive Touchscreen Weighted Coordinate Determination
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Solution Overview
Problem
Projected capacitive touchscreens face challenges in accurately determining touch coordinates due to the reliance on a large number of narrow electrodes, leading to unreliable measurements, especially when fewer electrodes detect a touch, resulting in inaccurate vertical coordinate calculations.
Innovation Solution
A capacitive touchscreen system with interlaced triangular electrodes on a substrate, where a controller applies different numerical weights to signals from adjacent electronic channels to determine the touch location based on signal clusters and local maximum signals, improving coordinate accuracy by favoring signals from interior electrodes over boundary regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a large number of narrow electrodes are used to detect touch coordinates, then the coverage area increases, but the measurement precision deteriorates due to unreliable signals from fewer detecting electrodes
Solution Approach 1:
The patent applies different weight values to different electrodes based on their local characteristics. Interior electrodes (surrounded by other electrodes) are assigned higher weights than boundary electrodes, recognizing that interior electrodes provide more reliable signals. This local differentiation resolves the contradiction by optimizing measurement precision locally at each electrode position while maintaining overall system coverage.
Solution Approach 2:
The patent changes the parameter of electrode signal weighting by introducing weight values that vary based on electrode position and signal characteristics. By dynamically adjusting the weight parameter rather than treating all electrodes equally, the system achieves higher coordinate measurement accuracy even with limited electrode detections, thus resolving the contradiction between coverage area and measurement precision.
2Device complexity
If each touch is detected by a modest number of electrodes, then the device complexity decreases, but the reliability of coordinate determination deteriorates due to insufficient signal data
Solution Approach 1:
The patent recognizes that not all electrodes contribute equally to reliable coordinate determination. By assigning higher weights to interior electrodes and lower weights to boundary electrodes, the system optimizes the contribution of each electrode based on its local reliability characteristics. This allows the system to achieve high coordinate determination reliability with a modest number of electrodes by focusing on the most reliable signal sources.
Solution Approach 2:
The patent replaces the mechanical approach of increasing electrode quantity to improve reliability with a computational approach using weighted signal processing. Instead of adding more electrodes to the physical system, the patent substitutes a mathematical weighting mechanism that amplifies reliable signals and suppresses unreliable ones, achieving the same reliability improvement with lower device complexity.
3Ease of operation
If equal weights are applied to all electrode signals, then the calculation simplicity increases, but the measurement precision deteriorates due to equal treatment of reliable and unreliable signals
Solution Approach 1:
The patent introduces local quality differentiation through position-based weighting, where interior electrodes receive higher weights than boundary electrodes. This resolves the contradiction by maintaining relatively simple calculation procedures while improving measurement precision through localized weight adjustments that account for the different reliability characteristics of electrodes in different positions.
Solution Approach 2:
The patent changes the weight parameter from a uniform value to a variable value that depends on electrode position and signal characteristics. This parameter change enables the system to differentiate between reliable and unreliable signals while maintaining computational efficiency, thus resolving the contradiction between calculation simplicity and measurement precision.
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 the reliability of touch coordinate determination by weighting signals from electrodes closer to the touch center more heavily, reducing errors in vertical coordinate calculations and providing more accurate touch location identification.
Implementation Method 1
the touchscreen system senses a change in capacitance associated with one or more of the electrodes
Data Source
AI summary
A touch location on a capacitive touchscreen system is identified by receiving signals in response to a touch from electronic channels connected to one electrode or to a group of semi-adjacent electrodes provided on a substrate. Adjacent ones of the electrodes have substantially triangular shapes that alternate between a first and second orientation to form an interleaved arrangement such that the touch generates a signal cluster comprising the signals generated from a series of adjacent electronic channels. Weights with at least two different numerical values are applied to the signals from the series of adjacent electronic channels. The at least two different numerical values are based on levels of the signals. A location of the touch on the substrate is determined based on the weighted signals.