Infrared Touch Interface Dynamic Modulation for Interference Rejection
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Solution Overview
Problem
Infrared touch screens are prone to malfunctions due to incident infrared light from sources like sunlight or artificial lighting, which can interfere with the detection of touch events, leading to inaccurate input recognition.
Innovation Solution
A touch sensitive user interface that dynamically adjusts the driving signal of infrared light sources, using modulation techniques such as constant current, square wave, or triangular wave to differentiate and filter out interfering infrared light, allowing the control unit to accurately determine touch events by analyzing signal reception patterns and modulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If infrared light sources are constantly driven with the same driving signal, then the touch sensitive user interface operates continuously, but it becomes more prone to malfunctions caused by incident infrared light
Solution Approach 1:
The patent applies periodic action by modulating the driving signal of infrared light sources with different modulation frequencies. Instead of constant driving, the system uses periodic modulation where each infrared light source is driven at a unique frequency, allowing the control unit to distinguish between modulated signals from light sources and unmodulated incident infrared light through frequency analysis
Solution Approach 2:
The patent implements parameter changes by varying the modulation frequency parameter of the driving signal. The control unit analyzes received infrared signals based on their modulation frequency characteristics, enabling differentiation between intentionally modulated light source signals and unmodulated incident infrared light, thus resolving the susceptibility problem
2Reliability
If the control unit permanently analyzes signals from infrared receivers to detect interference, then interference detection capability is improved, but the complexity of signal processing increases
Solution Approach 1:
The patent implements feedback by having the control unit continuously monitor and analyze signals from infrared receivers, using the modulation frequency information as feedback to determine whether detected infrared light originates from modulated light sources or unmodulated incident light, enabling adaptive interference detection
Solution Approach 2:
The patent uses modulation frequency as an intermediary characteristic that simplifies signal processing. By encoding light source signals with distinct modulation frequencies, the control unit can use frequency discrimination as an intermediate step to easily differentiate between modulated signals and unmodulated incident infrared light, reducing processing complexity
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
The solution enhances the robustness and stability of infrared touch screens by effectively filtering out interference, ensuring reliable operation even under conditions of incident infrared light, thereby improving user interaction accuracy.
Implementation Method 1
a plurality of infrared light sources (105, 106, 205, 206, 306, 406) arranged on at least two opposite edges of the display device (150, 250) and providing driving signals (211) for the infrared light sources (105, 106, 205, 206, 306, 406) with different modulation frequencies
Implementation Method 2
a plurality of infrared receivers (101, 102, 201, 202) arranged on at least two opposite edges of the display device (150, 250) and receiving infrared light from the infrared light sources (105, 106, 205, 206, 306, 406) with different modulation frequencies
Data Source
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AI summary
The present invention provides a touch sensitive user interface (100, 200, 300, 400) for a display device (150, 250), the touch sensitive user interface (100, 200, 300, 400) comprising a plurality of infrared receivers (101, 102, 201, 202) arranged on at least one first edge (103, 104) of the four edges of the display device (150, 250), a plurality of infrared light sources (105, 106, 205, 206, 306, 406) arranged on at least one second edge (107, 108) of the four edges of the display device (150, 250) that is opposite to the first edge (103, 104), and a control unit (210, 410) configured to analyze signals received by the infrared receivers (101, 102, 201, 202) for interferences and to adapt a modulation of driving signals (211) of the infrared light sources (105, 106, 205, 206, 306, 406) based on a result of the analysis of the signals received by the infrared receivers (101, 102, 201, 202). Further, the present invention provides a method for operating a touch sensitive user interface.