Multi-touch sensing dead zone elimination
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Solution Overview
Problem
Multi-touch recognition devices suffer from reduced touch recognition rate and accuracy due to dead zones and generate virtual images due to shadow effects, leading to incorrect coordinate recognition.
Innovation Solution
A multi-touch sensing apparatus and method using first and second pairs of image sensors installed near the corners of a touch surface, with a memory to store dead zone coordinates and a processor to calculate and compare touch point coordinates, selecting accurate coordinates to eliminate dead zone interference and virtual images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a multi-touch recognition device uses image sensors to detect touch points, then touch detection capability is improved, but dead zones are generated between sensor pairs where touch recognition rate and accuracy are significantly reduced
Solution Approach 1:
The touch surface is divided into multiple regions, each monitored by different pairs of image sensors. When a touch occurs in a dead zone of one sensor pair, another sensor pair that does not have a dead zone at that location can still detect it. This segmentation approach ensures that the entire touch surface is covered without dead zones by distributing sensor pairs strategically.
Solution Approach 2:
Different sensor pairs are assigned to monitor different local regions of the touch surface. Each sensor pair has its own characteristics and dead zone locations, so by assigning them to different regions, the system ensures that no single location on the touch surface is a dead zone for all sensors simultaneously.
2Device complexity
If coordinate values are calculated from a single pair of image sensors, then calculation simplicity is improved, but virtual images are generated due to shadow effects leading to incorrect coordinate recognition
Solution Approach 1:
The system merges the detection results from multiple sensor pairs by comparing coordinate values. When multiple sensor pairs detect the same touch point, their coordinate values are compared and the most accurate one is selected. This combining approach eliminates virtual images caused by shadow effects while maintaining reasonable calculation complexity.
Solution Approach 2:
The system uses feedback by comparing coordinate values from different sensor pairs to identify and eliminate virtual images. When a virtual image is detected, the system uses information from other sensor pairs to correct the coordinate recognition, ensuring accurate touch position detection.
Data Source
AI summary
A multi-touch sensing method and apparatus are described. The multi-touch sensing method includes: storing, in a memory, coordinate values of a first dead zone and coordinate values of a second dead zone existing between first and second pair of image sensors, respectively; calculating coordinate values of touch points from images obtained by the first and second pairs of image sensors; comparing the coordinate values of the touch point and the coordinate values of the dead zones to identify the location of the dead zone to which the touch point belongs; selecting the coordinate values calculated in the third step if the coordinate values of the touch point belong to the first dead zone; and selecting the coordinate values calculated in the second step if the coordinate values of the touch point belong to the second dead zone.