Resistive Multi-Touch Aperture Filtering for Distortion-Free Sensing
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Solution Overview
Problem
Conventional resistive touch screen controllers face difficulties in resolving multiple simultaneous touch events and are costly in terms of power consumption and area due to complex algorithms and interpolation processes.
Innovation Solution
The method involves identifying zones associated with touch events by measuring resistances across column and row electrodes, generating digital representations of coordinates and pressure, and using an aperture filter register to store and process these data, enabling efficient multi-touch capability without exotic algorithms and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional algorithms and interpolation processes are used to resolve multiple simultaneous touch events, then touch position accuracy is improved, but power consumption and device area increase
Solution Approach 1:
The touch screen is divided into multiple zones, and the controller sequentially activates different column and row segments to measure resistances for each zone. This segmentation allows the system to process multi-touch events by breaking down the complex measurement into manageable zones, reducing the need for complex interpolation algorithms while maintaining accuracy.
Solution Approach 2:
The controller uses periodic activation of columns and rows to measure resistances at different time intervals. By sequentially activating different electrode combinations and measuring resistances at periodic intervals, the system can resolve multiple touch positions without requiring all electrodes to be active simultaneously, thereby reducing power consumption.
2Measurement precision
If conventional algorithms and interpolation processes are used to resolve multiple simultaneous touch events, then touch position accuracy is improved, but device area increases
Solution Approach 1:
The touch controller divides the screen into zones and uses sequential activation of column and row segments. This approach eliminates the need for large interpolation circuitry by using simple resistance measurements across segmented electrodes, significantly reducing the device area required for the touch controller.
Solution Approach 2:
The patent replaces complex mechanical interpolation circuits with electrical resistance measurement and calculation. By using ohm's law and resistance ratios to determine touch positions, the system eliminates the need for physical interpolation hardware, reducing device area.
3Productivity
If aperture filter register is used to store digital representations, then processing efficiency is improved, but memory requirements increase
Solution Approach 1:
The patent extracts only the essential touch data (resistance values and zone identifiers) into aperture filter registers, storing only what is necessary for multi-touch resolution. By extracting and storing only critical parameters rather than complete waveforms or raw data, the system improves processing efficiency while minimizing memory requirements.
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 allows for accurate determination of multiple touch positions with reduced power consumption and area requirements, effectively handling simultaneous touch events and eliminating distortions caused by resistive loops and nonlinear resistance at the edges of touch sensors.
Implementation Method 1
measuring a first set of coordinates and a first pressure at a first touch event based on first, second, third, and fourth resistances
Data Source
AI summary
An apparatus comprises touch screen interface and signal processing circuit. Within touch screen interface, there are switching circuits configured to be coupled to at least one of a plurality of column electrodes, and there are touch detection circuits configured to be coupled to at least one of a plurality of row electrodes. The signal processing circuit is coupled to each switching circuit and each touch detection circuit so as to be able to selectively activate the plurality of switching circuits and touch detection circuits to identify a zone for a touch event. The signal processing circuit determines first, second, third, and fourth resistances for the zone for the touch event and determines a set of coordinates and pressure for the touch event from its first, second, third, and fourth resistances wherein an aperture filter register is in a host interface that also stores the first digital representation.