Optical Touch Sensing Device Palm Touch Detection
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Solution Overview
Problem
Optical touch sensing devices face challenges in distinguishing inadvertent palm touches due to their sensor working principles, making it difficult to determine palm contact based on the size of the covering region of a touch signal, especially as the distance from the touch object to the image capturing unit increases.
Innovation Solution
The optical touch sensing device determines the spacing between touch signals and evaluates the covering parameters to identify touch signals with larger areas, determining these as potential palm or large object touches, and ignores them accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the distance from the touch object to the image capturing unit increases, then the field of view increases, but the covering region of the touch object in the captured image decreases
Solution Approach 1:
The patent changes the parameter used for touch detection from covering region area to touch signal spacing. By calculating the distance between touch signals rather than relying on the area they occupy in the image, the system achieves accurate palm touch detection regardless of the distance between the touch object and image capturing unit.
2Weight of moving object
If the electronic device becomes lighter and thinner, then the portability improves, but the space for user holding decreases causing inadvertent palm touches
Solution Approach 1:
The patent uses image capturing units to create optical copies of touch objects on the touch surface. By analyzing the spacing between these optical copies (touch signals) rather than physical contact pressure, the system can distinguish between intentional finger touches and inadvertent palm touches, preventing misoperations while maintaining thin device design.
3Device complexity
If the covering region size is used as the basis for determining palm touch, then the detection method is simple, but the detection accuracy decreases in optical touch devices
Solution Approach 1:
The patent transitions from two-dimensional area measurement to one-dimensional spacing measurement. By calculating the distance between touch signal positions along the touch surface rather than measuring the area they cover in the image plane, the system achieves accurate palm touch detection that is independent of distance from the image capturing unit.
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 method effectively identifies and ignores inadvertent palm touches, enhancing the accuracy of optical touch sensing devices in preventing misinterpretation of touch signals.
Implementation Method 1
The light source module provides a detecting light to the touch surface
Implementation Method 2
The image capturing element captures an optical touch data along the touch surface based on the detecting light
Data Source
AI summary
An optical touch sensing device and a touch signal determining method thereof are provided. The optical touch sensing device includes a light source module, at least one image capturing element and a processing unit. The light source module disposed on a touch surface provides a detecting light to the touch surface. The image capturing element captures an optical touch data along the touch surface based on the detecting light. The processing unit recognizes the optical touch data according to a recognition threshold to obtain multiple touch signals. When a object spacing between the touch signals is no bigger than a palm spacing, the processing unit compares the covering parameters corresponding to the touch signals to select a largest covering parameter among the covering parameters, and determines whether to ignore the touch signal corresponding to the largest covering parameter according to the largest covering parameter and an area threshold.