Multi-touch Detection Grid Sensor Scanning
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Solution Overview
Problem
Existing multi-touch detection methods in grid-based sensors require scanning all sensor lines to determine user interactions, which limits the report rate, sensor size, and resolution due to significant processing and time requirements.
Innovation Solution
The method involves identifying portions of the sensor affected by user interactions without scanning conductive lines, allowing only those areas to be scanned, reducing the number of lines that need to be scanned and thereby decreasing overall detection time and sensitivity to noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all sensor lines are scanned to detect multi-touch positions, then detection accuracy is maintained, but report rate decreases and processing time increases
Solution Approach 1:
The sensor array is divided into multiple zones, with sensor lines grouped into first sensor lines and second sensor lines. Different scanning strategies are applied to different zones: first sensor lines are scanned completely to maintain detection accuracy, while second sensor lines use reduced scanning (sampling only every Nth line) to increase report rate. This segmentation allows the system to achieve both high accuracy and high productivity simultaneously.
2Reliability
If all sensor lines are scanned to determine user interactions, then detection completeness is ensured, but detection time increases
Solution Approach 1:
The system performs preliminary scanning of first sensor lines at full resolution to identify touch events and their approximate locations. Based on this preliminary information, the system then performs selective scanning of second sensor lines with reduced resolution. This preliminary action allows the system to maintain detection completeness while significantly reducing overall detection time by avoiding full scanning of all lines.
3Area of stationary object
If full sensor array is scanned, then sensor size can be large, but processing requirements increase
Solution Approach 1:
The system implements partial scanning of the sensor array by sampling every Nth line for second sensor lines, rather than scanning all lines at full resolution. This partial action reduces processing requirements and allows larger sensor arrays to be managed efficiently, while still maintaining adequate detection capability for multi-touch events across the full sensor area.
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 increases the report rate, size, and resolution of the sensor by limiting the area scanned, reducing false positives, and enhancing sensitivity, while maintaining efficient processing requirements.
Implementation Method 1
the digitizer sensor includes a series of activated electrodes and passive electrodes... An AC signal, e.g. a pulsed AC signal, sequentially activates each of the activated electrodes. In response to each AC signal applied, a signal is transferred, by capacitive coupling, to each of the passive electrodes. The presence of a finger or an object typically alters the signal transferred to some of the passive electrodes.
Data Source
AI summary
A method for multi-touch detection in a touch input device comprising a grid based sensor, the method comprises sampling outputs from a grid based sensor over a first stage of detection, selecting sensor lines based on the sampled outputs, scanning the selected sensor lines along one axis of the grid based sensor over a second stage of detection, and determining positions of user interaction based on outputs sampled in response to scanning the selected sensor lines during the second stage of detection.