Single Camera Optical Touch Detection Using Retro-Reflection
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Solution Overview
Problem
Conventional camera-based touch detection systems require multiple cameras, increasing manufacturing costs and complexity, and lack an efficient method for accurately determining touch locations on a touch panel.
Innovation Solution
An optical touch detection apparatus using a single imaging device with a light source and retro-reflector, which acquires images of the touch panel, processes signal arrays to determine pointer location through peak signal analysis, and calibrates coefficients using predefined threshold comparisons and image data from multiple touch locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple cameras are used to detect touch locations, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent segments the touch detection function by using a single camera to capture different views of the touch panel at different angles, rather than using multiple cameras simultaneously. The touch panel is divided into multiple detection zones that can be sequentially imaged by the single camera, achieving complete touch detection coverage without requiring multiple camera units.
Solution Approach 2:
The patent introduces the time dimension by sequentially capturing images at different angles or positions, transforming a spatial problem (requiring multiple cameras) into a temporal solution (single camera taking multiple shots). This allows the system to reconstruct three-dimensional touch information through time-sequential two-dimensional imaging.
2Measurement precision
If multiple cameras are used to detect touch locations, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent segments the touch detection function by using a single camera to capture different views of the touch panel at different angles, rather than using multiple cameras simultaneously. The touch panel is divided into multiple detection zones that can be sequentially imaged by the single camera, achieving complete touch detection coverage without requiring multiple camera units.
Solution Approach 2:
The patent uses image processing to create virtual copies of the touch panel view from different angles by processing a single captured image. Through coordinate transformation and image reconstruction algorithms, the system generates multiple virtual perspectives from one physical camera capture, eliminating the need for multiple physical cameras.
3Device complexity
If a single imaging device is used, then device complexity is reduced, but measurement precision may deteriorate
Solution Approach 1:
The patent makes the single imaging device dynamic by enabling it to change its viewing angle or position sequentially. The camera can rotate, translate, or tilt to capture different perspectives of the touch panel, allowing one static device to perform the function of multiple fixed devices through dynamic repositioning.
Solution Approach 2:
The patent implements feedback mechanisms where the system analyzes the captured image, determines touch location, and uses this information to adjust subsequent imaging parameters. The processor provides feedback to the imaging device about what needs to be captured next, optimizing the single device's performance to match or exceed multi-device systems.
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
This solution reduces manufacturing complexity and cost by using a single imaging device to accurately determine touch locations on a touch panel, enhancing the efficiency of touch detection while maintaining precision.
Implementation Method 1
a retro-reflector disposed on the periphery of the touch panel at a location that is opposite to the pre-selected mounting position so as to reflect light emitted from the light source backward to the image device
Data Source
AI summary
One aspect of the present invention relates to an apparatus for touch detection. In one embodiment, the apparatus includes a touch panel, an imaging device mounted to the touch panel and configured such that when a pointer touches the touch panel, the imaging device acquires an image of the pointer touching the touch panel, and a processor in communication with the imaging device for receiving and processing the acquired image to obtain its width and its angle relative to the touch panel so as to determine the location of the pointer in the touch panel.