Optical Touch System Multiple Point Detection via Dark Area Analysis
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Solution Overview
Problem
Optical touch systems struggle to accurately detect multiple touch points on a screen, often resulting in incorrect coordinates due to insufficient information from captured images, especially when touch points overlap or are partially shaded.
Innovation Solution
A method and system that utilize a panel, camera units, and data processing to analyze dark areas corresponding to touch points, determining their positions and coordinates by judging the union dark area width and using stored area information to calculate precise coordinates, even in overlapping or shading scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a general optical touch technique is used to detect touch points, then a single touch point can be correctly detected, but multiple touch points result in incorrect coordinates
Solution Approach 1:
The patent segments the detection process into multiple stages: first detecting the union dark area, then dividing it into individual dark areas corresponding to each touch point. By analyzing the union dark area width and comparing it with individual dark area widths, the system can distinguish and calculate coordinates for multiple touch points separately, resolving the inability to detect multiple touches accurately
Solution Approach 2:
The patent introduces a temporal dimension by comparing the current frame's dark area information with the previous frame's information. By analyzing changes in union dark area width across frames and using stored area information from previous detections, the system can track and distinguish multiple touch points even when they overlap or are partially shaded
2Loss of information
If one touch point shades another touch point, then the captured image lacks sufficient information, but the system still needs to calculate exact coordinates of both touch points
Solution Approach 1:
The patent performs preliminary detection and stores area information (such as dark area width) from the previous frame before the shading occurs or while partial information is still available. This stored information is then used to supplement and correct the current frame's incomplete data, allowing the system to calculate accurate coordinates even when one touch point shades another
Solution Approach 2:
The system uses feedback from the previous frame's detection results to inform the current frame's calculation. By comparing the union dark area width with stored individual dark area widths and analyzing the changes between frames, the system can infer the positions of shaded touch points and calculate their coordinates accurately
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 approach enhances the precision of detecting multiple touch points by accurately determining their positions and coordinates, improving the accuracy of optical touch input systems and preventing errors in coordinate calculation.
Implementation Method 1
When a user touches a screen by his finger, the finger blocks the light relative to a certain position of the screen and then an image captured by a camera unit has a dark area accordingly
Data Source
AI summary
The invention discloses a method of distinguishing multiple touch points applied to an optical touch system which includes a panel for indicating a first touch point and a second touch point thereon and a camera unit for capturing an image relative to the first touch point and the second touch point. The image has a first dark area and a second dark area corresponding to the first touch point and the second touch point respectively. In the method, if it is observed that the first dark area and the second dark area merge into a first single dark area and a second single dark area at current time and previous time respectively, the respective positions of the first dark area and the second dark area are determined and the respective coordinates of the first touch point and the second touch point are also determined.