Optical Touch System Multi-Finger Recognition via Temporal Signal Analysis
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Solution Overview
Problem
Conventional optical touch screens misjudge multi-finger touches as single-finger operations due to overlapping images captured by optical lenses, leading to a decreased recognition rate for multi-touch inputs.
Innovation Solution
An optical touch system and method that calculates touch points by analyzing images captured by two lenses before and after a predetermined time, determining width differences, and using threshold values specific to screen positions to distinguish between single and multi-finger touches, thereby accurately determining touch positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical touch screens use optical lenses to capture finger images for position detection, then single-finger touch detection accuracy is high, but multi-finger touch recognition rate decreases due to image overlap
Solution Approach 1:
The patent segments the touch detection process into multiple time frames. By capturing images at different time points and analyzing the temporal sequence of touch events, the system can distinguish between single-finger and multi-finger touches even when their images overlap in space. This temporal segmentation allows the system to track individual finger movements separately, resolving the contradiction between single-finger accuracy and multi-finger recognition.
2Device complexity
If optical lenses are positioned at screen corners to capture touch images, then device structure is simplified, but image overlap occurs when fingers are close together
Solution Approach 1:
The patent adds the time dimension to the spatial detection process. Instead of relying solely on spatial separation of lenses, the system uses temporal sequencing of touch events to differentiate between multiple fingers. By analyzing the sequence and timing of touch signals, the system can accurately detect multi-finger positions even with a simplified corner-lens configuration, effectively adding a temporal dimension to resolve the spatial overlap problem.
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
Improves the recognition rate of multi-touch inputs by accurately differentiating between single and multi-finger touches, reducing misjudgment and enhancing the system's ability to detect multiple touch points.
Implementation Method 1
a position of finger shadow in the captured image generated due to that the finger interrupts the light is analysed
Data Source
AI summary
An optical touch system and a touch point calculation method thereof are provided. The optical touch system includes a first lens, a second lens and a screen. The first and second lenses are disposed on the same side of the screen and face to the other side of the screen. In the method, images of a touch object above the screen are captured and used to calculate a first and a second touch signal of the touch object touching the screen before and after a preset time. Then, it is determined whether a width difference of the first and second touch signals exceeds a predetermined threshold. If yes, a third touch signal corresponding to the first touch signal relative to the second touch signal is calculated. Finally, positions of the first touch signal and the third touch signal are taken as locations of two touch points on the screen.