Optical Touch Image Subtraction for Ambient Light Interference

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Solution Overview

Problem

Existing optical touch devices face challenges in accurately recognizing touch objects due to interference from ambient light, leading to increased power consumption and reduced lifespan of infrared light sources.

Innovation Solution

A method involving alternating the infrared light source's activation based on preset intervals, capturing dual images with and without light, and performing subtraction to eliminate interference, thereby optimizing touch object recognition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the infrared light source power is increased to eliminate interference objects, then the recognition accuracy of touch objects is improved, but the power consumption increases and lifespan decreases

Engineering Contradiction:

Improverecognition accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies periodic action by alternating the infrared light source between on and off states at regular intervals. The controller turns on the infrared light source for a first duration to capture images with infrared illumination, then turns it off for a second duration to capture images without infrared illumination. This periodic switching enables the system to eliminate interference objects through image subtraction while significantly reducing power consumption compared to continuous operation at high power.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent converts the harmful effect of ambient light interference into a beneficial solution. By capturing images both with and without infrared illumination and performing subtraction, the system uses the interference-containing images to generate a difference image that eliminates interference objects. This transforms the problematic ambient light interference into a useful mechanism for achieving clear touch object recognition without requiring high power.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Measurement precision

If the infrared light source power is increased to eliminate interference objects, then the recognition accuracy of touch objects is improved, but the lifespan of the infrared light source decreases

Engineering Contradiction:

Improverecognition accuracyVSAvoidlifespan

Core Design Contradiction:

Measurement precisionVSDuration of action of stationary object

Solution Approach 1:

The periodic switching between on and off states reduces the cumulative operating time of the infrared light source while maintaining effective recognition capability. By operating intermittently rather than continuously at high power, the total stress on the light source is reduced, thereby extending its operational lifespan while still achieving the necessary recognition accuracy during the on periods.

Inventive Principle:

Principle #19Periodic action

3Measurement precision

If the infrared light source is turned on continuously to improve recognition speed, then the recognition accuracy is improved, but the power consumption increases

Engineering Contradiction:

Improverecognition accuracyVSAvoidrecognition speed

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The periodic action maintains recognition speed by ensuring the infrared light source is on during critical capture periods. The first duration (when infrared is on) is optimized to capture necessary image data, and the alternating pattern ensures continuous operation cycles that maintain system responsiveness and recognition speed while reducing overall power consumption compared to continuous operation.

Inventive Principle:

Principle #19Periodic action

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

Enhances recognition speed and accuracy while reducing power consumption and extending the lifespan of the infrared light source.

Implementation Method 1

an infrared light source, a touch panel, and two or more cameras. The optical touch device operates by continuously turning on the infrared light source at uniform intervals

Methodology Applied

Scientific EffectInfrared radiation: Infrared Radiation

Implementation Method 2

the cameras capture images of the touch object as the touch object image

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS12488552B2Method, apparatus, optical touch device, and storage medium for optical touch image optimization

Publication Date: 2025.12.02 KOGA TOUCH CO LTD

AI summary

The present disclosure provides a method, apparatus, optical touch device, and storage medium for optical touch image optimization, including turning on an infrared light source based on a preset second interval, wherein the infrared light source is configured to illuminate a touch object of the optical touch device; capturing, at each time the infrared light source is turned on, a first optical touch image and a second optical touch image based on a preset first interval, wherein the first optical touch image is the image captured when the infrared light source is turned on, and the second optical touch image is the image captured when the infrared light source is turned off; and performing subtraction between the first optical touch image and the second optical touch image to obtain an optimized optical touch image, wherein the optimized optical touch image includes the touch object.