Camera Module Optical Touch Screen Infrared Filtering
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Solution Overview
Problem
Existing touch screen technologies face limitations in mechanical and environmental reliability, noise susceptibility, and the inability to detect multiple contact points simultaneously, with optical touch screens suffering from reduced transmittance and brightness issues.
Innovation Solution
A camera module incorporating an infrared emitting diode, first and second infrared pass filters, and a linear sensor is used to detect touch inputs by filtering and condensing infrared rays, enhancing sensing efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If optical touch screens use no films for touch recognition, then transmittance is 100% and brightness is maintained, but the ability to filter specific infrared wave bands is insufficient
Solution Approach 1:
The optical touch screen system is segmented into multiple functional components: infrared emitting diodes for light source, object lenses for condensing infrared rays, first infrared pass filters for initial filtering, second infrared pass filters for specific wave band selection, and linear sensors for detection. This segmentation allows each component to optimize its function while maintaining overall 100% transmittance.
Solution Approach 2:
Infrared pass filters are introduced as intermediary elements between the infrared emitting diodes and linear sensors. These filters act as mediators that selectively transmit specific infrared wave bands while blocking others, enabling precise touch detection without compromising the optical transparency of the screen.
2Measurement precision
If infrared pass filters are added to detect specific wave bands, then sensing efficiency is improved, but device complexity increases
Solution Approach 1:
The camera module is designed with multi-functionality, serving both as an infrared detection device and an optical touch screen component. The object lens and infrared pass filters are integrated into the existing camera module structure, allowing the same module to perform both infrared ray condensing/filtering and touch detection functions, thereby reducing overall system complexity.
Solution Approach 2:
The patent merges the infrared detection function with the touch screen function by integrating infrared emitting diodes, object lenses, infrared pass filters, and linear sensors into a unified camera module. This combination eliminates the need for separate infrared detection systems, reducing device complexity while maintaining sensing efficiency.
3Measurement precision
If multiple infrared pass filters are used to block unwanted wave bands, then detection accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
The first infrared pass filter is positioned before the object lens to perform preliminary filtering of infrared rays. This preliminary action removes unwanted wave bands before they reach the condensing lens, simplifying the subsequent filtering process and reducing the complexity of assembling multiple filters in precise configurations.
Solution Approach 2:
Different infrared pass filters are positioned at different locations within the camera module, each with specific filtering characteristics tailored to its local function. The first filter handles broad infrared filtering, while the second filter provides specific wave band selection, allowing each component to be optimized for its specific manufacturing and assembly requirements.
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 effectively increases sensing efficiency by blocking unwanted infrared wave bands and detecting touches with a specific wave band, improving the reliability and accuracy of touch input detection.
Implementation Method 1
an infrared emitting diode for emitting infrared ray
Implementation Method 2
a first infrared pass filter passing only the infrared ray reflected by a retro reflector
Implementation Method 3
an object lens condensing the infrared ray that has passed the first infrared pass filter
Implementation Method 4
a second infrared pass filter passing an infrared ray of a particular wave band among the infrared ray condensed by the object lens
Implementation Method 5
a linear sensor for detecting an area touched by incidence of infrared ray that has passed the second infrared pass filter
Implementation Method 6
the infrared ray reflected by a retro reflector
Data Source
AI summary
The present invention relates to a camera module and an optical touch screen using the same, the camera module including an infrared emitting diode for emitting infrared ray, a first infrared pass filter passing only the infrared ray reflected by a retro reflector, an object lens condensing the infrared ray that has passed the first infrared pass filter, a second infrared pass filter passing an infrared ray of a particular wave band among the infrared ray condensed by the object lens, and a linear sensor for detecting an area touched by incidence of infrared ray that has passed the second infrared pass filter.