Touchscreen Sensor Arrays with Stray Light Guards
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Solution Overview
Problem
Existing touchscreens face challenges in accurately detecting touch events due to stray light interference from edges, especially under bright conditions like sunlight, which can lead to sensor saturation and inaccurate touch location determination.
Innovation Solution
The touchscreen apparatus incorporates sensor arrays with light transmitters and sensors on opposing edges, featuring physical obstacles such as guards and optical filters to reduce stray light, and uses sequential light pulse transmission to enhance detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical obstacles (guards, optical filters) are added to reduce stray light, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts and removes stray light from the optical path by introducing physical obstacles (guards and optical filters) that selectively block scattered light while allowing direct light to pass through. This separation of useful light from harmful stray light resolves the contradiction by improving measurement precision without fundamentally changing the core sensor array structure.
Solution Approach 2:
The patent introduces intermediary elements (guards and optical filters) between the light source and sensors that mediate the interaction by filtering out harmful stray light components. These intermediaries act as buffers that improve touch detection accuracy while maintaining a relatively simple overall device architecture.
2Measurement precision
If sequential light pulse transmission is used to enhance detection accuracy, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The patent employs periodic action by transmitting light in sequential pulses rather than continuous illumination. Each pulse is timed to coincide with sensor activation, allowing for multiple measurement opportunities while minimizing total energy consumption. This periodic transmission scheme improves detection accuracy through multiple samples while managing energy usage efficiently.
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 design effectively minimizes stray light interference, enhances touch event detection, and maintains accuracy even in bright conditions, ensuring precise location determination of touch events.
Implementation Method 1
light from each of the light transmitters in one of the first sensor array and the second sensor array is directed along a direct light path to be detected by at least one light sensor of other sensor array
Implementation Method 2
at least one physical obstacle, located on at least one of the third edge or the fourth edge, for reducing stray light scattered or reflected by said at least one of the third edge or the fourth edge and arriving to the light sensors
Implementation Method 3
stray light scattered or reflected by said at least one of the third edge or the fourth edge
Data Source
AI summary
A touch screen (TS) comprises a display; a frame with edges positioned opposite each other around the display; at least a first sensor array and at least a second sensor array, wherein each of the sensor arrays has a plurality of light transmitters and a plurality of light sensors, and wherein the at least first sensor array and the at least second sensor array are disposed on the first edge and the second edge of the frame, respectively, wherein the transmitters of the first sensor array are facing the light sensors on the second sensor array positioned on two opposing edges of the frame; and at least one physical obstacle located on the third edge or the fourth edge, for reducing stray light scattered or reflected by third edge or the fourth edge and arriving to the light sensors.