Optical Touch Display Ghost Coordinate Elimination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical touch display systems face reduced measurement accuracy for multiple touch points due to shadowing and obstruction of light paths, leading to incorrect coordinates, known as ghost coordinates, which complicates applications requiring precise touch point detection.
Innovation Solution
The optical touch display system employs a light source, reflector, and image sensors to generate two-dimensional images of touch points, including real and virtual images, which are processed to determine accurate coordinates using distance and angle measurement devices, enhancing accuracy by distinguishing between real and virtual images and calculating precise positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If image sensors are disposed at corners of touch screens and triangulation is used to determine coordinates, then manufacturing cost is reduced and structure is simplified, but measurement accuracy deteriorates due to shadowing and obstruction of light paths
Solution Approach 1:
The patent transitions from 2D corner-based image sensor arrangement to a 3D configuration where the light source is positioned above the touch screen surface. This vertical dimension addition allows light to illuminate touch points from above, preventing shadowing issues while maintaining cost-effective manufacturing.
Solution Approach 2:
The patent introduces a reflective layer as an intermediary between the touch screen surface and the image sensors. This reflective layer redirects light paths, enabling accurate coordinate detection for multiple touch points without requiring complex multi-sensor arrangements, thus maintaining manufacturing simplicity while improving measurement accuracy.
2Device complexity
If image sensors are disposed at corners of touch screens, then device complexity is reduced, but measurement precision deteriorates due to ghost coordinates
Solution Approach 1:
The patent replaces the mechanical arrangement of multiple image sensors at corners with an optical solution using a centrally positioned light source above the touch screen. This substitution maintains low device complexity while eliminating ghost coordinates through superior light path control.
Solution Approach 2:
The patent makes the central light source perform multiple functions: it illuminates the touch screen surface, creates virtual images for depth perception, and enables accurate coordinate detection for multiple touch points simultaneously. This multi-functionality reduces the need for additional components, keeping device complexity low.
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 enables accurate detection of multiple touch points by differentiating between real and virtual images, improving measurement accuracy and reducing ghost coordinates, thus enhancing the reliability of touch point positioning in optical touch display systems.
Implementation Method 1
a light source, disposed on a periphery of the touch region, the light source positioned at least partially above the touch region, such that light rays emitted from the light source may traverse the touch region
Implementation Method 2
a reflector, disposed on at least a part of the periphery of the touch region, for reflecting the light rays emitted from the light source and generating a mirrored image of the touch region
Implementation Method 3
an image sensor, disposed above the light source, for receiving light rays of the light source, reflected from a set of touch points on the touch region and the reflector, and generating a two-dimensional image accordingly
Data Source
AI summary
Optical touch display system includes a light source, a reflector, an image sensor, and a processing device. The light source emits light to at least one object directly and emits light to the at least one object via the reflector at the same time. Then the image sensor receives light reflected from the at least one object directly and light reflected via the reflector simultaneously to form a set of imaging objects which have similar color parameters on an image. Then the processing device produces a set of still image parameters of the image objects such as gravity centers and border boundaries. Based on the still image parameters, the processing device determines the coordinates of the least one object on the optical touch display.