Optical Touch Panel Ambient Light Interference Compensation
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Solution Overview
Problem
Optical touch panels are susceptible to interference from ambient light, which affects the accuracy of touch position sensing, especially when displaying various images.
Innovation Solution
A program that calculates touch data by fetching and calibrating sensor images with and without lighting, using weighted averages and illumination estimates to stabilize and enhance input data extraction, regardless of ambient light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ambient light enters the photo sensor unit, then the photo sensor unit can detect light signals, but ambient light interferes with the data signal and causes difficulties in touch position sensing
Solution Approach 1:
The patent applies preliminary action by capturing a reference image before touch detection and using it to calculate a reference value. This reference value represents the ambient light conditions and display state before touch occurs, allowing the system to compensate for ambient light interference during subsequent touch detection by comparing actual sensor data against this pre-calculated reference.
Solution Approach 2:
The patent implements feedback by continuously monitoring the photo sensor unit's output and comparing it against the reference value derived from pre-touch conditions. The system uses the difference between actual and reference measurements to isolate touch-induced signal changes from ambient light interference, thereby improving touch position sensing accuracy in varying ambient light conditions.
2Illumination intensity
If the light unit is turned on to illuminate the display, then the display becomes visible, but the light unit lighting state affects the sensor image and complicates touch data extraction
Solution Approach 1:
The patent applies preliminary action by capturing a reference image in a known lighting state (with or without the light unit on) before touch detection begins. This reference image serves as a baseline that accounts for the specific lighting conditions, allowing the system to isolate touch-induced changes from lighting variations during the actual touch measurement phase.
Solution Approach 2:
The patent extracts the lighting condition information from the reference image and uses it to calculate a reference value that represents the expected sensor output under those lighting conditions. By separating and analyzing the lighting component independently through the reference value, the system can then focus on extracting only the touch-related signal changes from the actual sensor data, simplifying the overall processing.
3Adaptability or versatility
If display images with various colors and brightness are shown, then the display provides rich visual information, but the display image affects the sensor signal and reduces touch sensing stability
Solution Approach 1:
The patent applies preliminary action by capturing a reference image before touch detection while the display is showing the specific image that will be present during touch measurement. This allows the system to pre-characterize the sensor signal expected under those specific display conditions (color, brightness, contrast), enabling accurate isolation of touch-induced signal changes regardless of the display content being shown.
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 provides more accurate and stable touch data extraction, improving the convenience and precision of information processing devices in varying ambient light and display scenarios.
Implementation Method 1
optical touch panels using photo sensor units serving as touch panels
Data Source
AI summary
A program includes first to fourth steps. The first step includes a step of fetching a first sensor image at the time when a light unit is lighting and a second sensor image at the time when the light unit is not lighting. The second step includes a step of calculating a third image by calibrating the first sensor image using a first calibration image; and a step of calculating a fourth image by calibrating the second sensor image using a second calibration image. The third step includes a step of calculating fifth to seventh images using the third image and the fourth image; and a step of calculating an eighth image by obtaining a weighted average of the fifth to the seventh images in accordance with an illumination and a display image. The fourth step includes a step of calculating touch data using the eighth image.