Optical Touch Screen Triangulation Signal Processing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing touch screen technologies face limitations such as reduced image clarity, susceptibility to glare, scratching, and incompatibility with non-human inputs, as well as issues with false readings due to ambient light and shadows, which affect their performance in various environments and applications.
Innovation Solution
A touch screen system utilizing light sources at the edges of the screen, combined with area or line scan cameras and advanced signal processing techniques like triangulation, filtering, and ambient light subtraction to accurately detect the presence and location of objects, regardless of ambient conditions, using LEDs and light deflectors for effective illumination and image capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If resistive touch screen technology is used, then it can be accessed with a finger, glove, pen, stylus, or hard object, but image clarity degrades due to layers of resistive film and susceptibility to scratching
Solution Approach 1:
The patent replaces the mechanical contact-based resistive touch system with an optical detection system using cameras and light sources. This substitution eliminates the need for physical contact layers, thereby maintaining versatility in input methods (fingers, gloves, stylus) while preserving image clarity by removing the degrading resistive film layers.
Solution Approach 2:
The patent introduces light sources and cameras as intermediary elements between the user and the display. These intermediaries enable touch detection through optical means rather than direct mechanical contact, allowing various input objects to interact with the screen without compromising image quality or introducing scratching risks.
2Reliability
If capacitive touch screen is used, then it is durable and resistant to water, dirt and dust, but it is only activated by human finger and not by gloved finger, pen, stylus or hard object
Solution Approach 1:
The optical detection system is designed to detect various input methods universally. The cameras and light sources can detect reflections and interruptions from any object type (fingers, gloves, pens, stylus, hard objects), making the system universally compatible while maintaining the durability of the glass overlay without requiring capacitive sensing limitations.
Solution Approach 2:
The patent replaces the capacitive sensing mechanism with an optical detection mechanism. This substitution allows the system to maintain the physical durability of the glass overlay while eliminating the limitation of human-finger-only activation, as optical detection can identify any object that interacts with the light field.
3Measurement precision
If surface acoustic wave technology is used, then image clarity, resolution, and light transmission are superior, but the touch screen cannot be gasket sealed and is not suitable for industrial or commercial applications
Solution Approach 1:
The patent replaces the surface acoustic wave mechanism with an optical detection system using cameras and light sources. This substitution allows the glass overlay to be fully sealed and gasketed for harsh environments, as the optical components can be positioned behind the sealed glass, maintaining image clarity while enabling environmental protection.
Solution Approach 2:
The patent moves the detection components (cameras and light sources) to a different spatial dimension - positioning them behind the glass overlay rather than requiring direct surface contact. This dimensional repositioning allows the glass to be fully sealed for industrial applications while the optical components remain functional through the transparent or translucent glass.
4Reliability
If infrared touch screen is used, then it can be completely sealed and operated using any hard or soft objects, but it is susceptible to early activation before finger or stylus has actually touched the screen and has high manufacturing cost
Solution Approach 1:
The patent employs feedback mechanisms through signal processing that analyzes the characteristics of light interruption patterns. By examining the spatial and temporal patterns of light blockage, the system can distinguish between actual touch events and false activations caused by ambient light or shadows, reducing false readings while maintaining sealed construction.
Solution Approach 2:
The system performs preliminary analysis of the optical signal patterns before registering a touch event. By pre-processing the camera data to identify characteristic touch patterns versus ambient light variations, the system can filter out false activations before they are registered, improving measurement precision while maintaining the sealed design.
5Ease of operation
If optical imaging touch screen is used, then it can detect objects without direct contact, but it is susceptible to false readings due to moving shadows and bright lights
Solution Approach 1:
The patent implements feedback through signal processing that continuously monitors and analyzes light patterns. By comparing current light interruption patterns with expected touch patterns and filtering out anomalies caused by ambient light changes or shadows, the system maintains accurate non-contact detection while minimizing false readings.
Solution Approach 2:
The system dynamically adjusts its detection algorithms based on ambient conditions. By adapting the signal processing parameters in response to changing light environments, the system can maintain accurate touch detection without direct contact while compensating for moving shadows and bright lights that would otherwise cause false readings.
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 system provides reliable object detection and location determination, resistant to ambient light variations and shadows, allowing for accurate user input in diverse environments without the need for direct contact, and offers flexible and efficient calibration.
Implementation Method 1
light including: direct light from said light sources, and/or reflected light from said light sources
Data Source
AI summary
A touch screen which uses light sources at one or more edges of the screen which directs light across the surface of the screen and at least two cameras having electronic outputs located at the periphery of the screen to receive light from said light sources. A processor receives the outputs of said cameras and employs triangulation techniques to determine the location of an object proximate to said screen. Detecting the presence of an object includes detecting at the cameras the presence or absence of direct light due to the object, using a screen surface as a mirror and detecting at the cameras the presence or absence of reflected light due to an object. The light sources may be modulated to provide a frequency band in the output of the cameras.