Optical Sensing Frame for Touch Detection
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Solution Overview
Problem
Conventional infrared type touch panels face issues such as complex mechanical and electronic configurations, reduced effective area, difficulty in adapting to different sizes, image quality deterioration, ghosting during multi-touch detection, and increased size and weight due to separate touch and liquid crystal modules, as well as dead zones near the edges.
Innovation Solution
A display device with an optical sensing frame featuring a waveguide unit and infrared camera sensors located at opposite ends, using a retro-reflector to emit and receive infrared light, allowing for touch detection by triangulating touch points and compensating for ghosting and dead zones, thus enabling efficient multi-touch sensing without the need for extensive edge coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional infrared type touch panels use separate touch and liquid crystal modules with extensive edge coverage for light emitting and receiving, then touch detection function is achieved, but device thickness increases and effective area is reduced
Solution Approach 1:
The patent combines the touch detection module with the liquid crystal display module into a single integrated structure. The light emitting unit and light receiving unit are positioned at opposite edges of the same panel, eliminating the need for separate modules. This merging reduces overall device thickness while maintaining full effective touch area, as the sensing frame is formed within the display panel itself rather than requiring additional external components.
2Reliability
If conventional infrared touch panels place light emitting and receiving units at all four edges, then complete touch detection coverage is achieved, but mechanical and electronic configuration becomes complex
Solution Approach 1:
The patent extracts the light emitting and light receiving functions from a complex four-edge configuration and concentrates them into opposite edge positions only. The sensing frame uses light emitting units at one pair of opposite edges and light receiving units at the other pair, eliminating redundant components. This extraction simplifies the mechanical structure and electronic configuration while maintaining complete touch detection coverage through the infrared matrix formed by the opposite edge positioning.
3Illumination intensity
If conventional touch panels use full reflective substrates with air gaps, then light reflection is achieved, but image quality deteriorates and manufacturing becomes difficult
Solution Approach 1:
The patent changes the optical parameters of the sensing frame by using a light shielding layer with specific optical properties instead of a full reflective substrate with air gap. The light shielding layer is positioned in direct contact with the liquid crystal panel without air gaps, eliminating image quality deterioration. The layer is configured to reflect infrared light for touch sensing while maintaining display quality, achieving both light reflection and manufacturing precision through parameter optimization.
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 simplifies the touch detection mechanism, enhances effective area utilization, improves image quality, reduces the device thickness, and allows for accurate multi-touch detection across the entire panel, including areas previously considered dead zones, while maintaining a slim structure.
Implementation Method 1
a waveguide unit 150 formed corresponding to one side of the display panel 100, the waveguide unit having a light emitting layer 151 configured to emit an infrared ray light and a light receiving layer 153 configured to receive a reflected-light
Implementation Method 2
a retro-reflector 300 formed corresponding to the other three sides of the display panel 100
Data Source
AI summary
A method of sensing touch on a display device having an optical sensing frame includes emitting first light from a sensor module, receiving a first reflection at the sensor module, emitting second light from a waveguide, receiving a second reflection at the waveguide, and if a touch is made on an optical sensing frame, detecting that reflections of the first and the second light are interfered and determining a change in the quantity of the first and second reflection received to determine the touch.