Optical Touch Sensor Ghost Touch Suppression via Divergent Beam Segmentation
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Solution Overview
Problem
Existing optical touchscreens face challenges in accurately identifying touch locations due to ghost touches, which occur when multiple touches are misinterpreted due to insufficient positional data, and they either suffer from poor signal levels or increased costs associated with more complex configurations.
Innovation Solution
The solution involves a configuration where light emitters are shift-aligned with respect to detectors, and light beams are split into multiple divergent beams with known intensity distributions, allowing for precise calculation of touch locations by maximizing signal gradients and providing additional detection channels to suppress ghost touches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light beams are made parallel to improve signal levels, then signal detection is enhanced, but ghost touches cannot be suppressed due to insufficient angular information
Solution Approach 1:
The patent segments each light beam from a single emitter into multiple divergent sub-beams using lenses. Each sub-beam travels at a different angle through the detection area, providing multiple angular perspectives. This segmentation allows the system to maintain good signal levels while suppressing ghost touches, as the angular diversity enables differentiation between real touches and ghost touches.
Solution Approach 2:
The patent introduces angular dimensionality by directing light beams at multiple different angles rather than parallel paths. By adding this angular dimension to the detection space, the system gains additional positional information that enables ghost touch suppression while maintaining signal strength, resolving the contradiction between signal level and reliability.
2Measurement precision
If multiple light channels are added to suppress ghost touches, then detection accuracy improves, but system cost and complexity increase
Solution Approach 1:
The patent makes each emitter-detector pair multi-functional by using lenses to create multiple detection channels from a single component pair. Each emitter-detector combination can detect touches at multiple locations simultaneously through its divergent sub-beams, reducing the total number of components needed while maintaining high measurement precision for ghost touch suppression.
Solution Approach 2:
The patent changes the optical parameters of the light beams by introducing controlled divergence angles through lens design. This parameter modification allows a single emitter-detector pair to function as multiple channels, achieving high touch location accuracy and ghost touch suppression without proportionally increasing the number of physical components.
3Ease of manufacture
If component pitch is increased to reduce complexity, then manufacturing cost decreases, but signal gradients become insufficient for precise touch location calculation
Solution Approach 1:
The patent introduces dynamic angular distribution through the lens system, where light from each emitter is distributed across multiple angles rather than a single fixed path. This dynamic beam distribution compensates for larger component pitch by providing angular diversity that maintains sufficient signal gradients for precise touch location calculation even when physical spacing between components is increased.
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 configuration enhances the accuracy of touch location detection by reducing ghost touches and maintaining good signal levels, while being cost-effective by optimizing the number of components and channels used.
Implementation Method 1
each light emitter operable when activated to project light beams through a respective one of the lenses
Implementation Method 2
the lenses are configured to split the light beam projected from each light emitter into a plurality of divergent light beams
Implementation Method 3
a plurality of light detectors mounted on the circuit board along the edge of the rectangular detection area that is opposite the specific edge, each detector receiving the light beams directed across the rectangular detection area through a respective one of the lenses
Data Source
AI summary
A method for detecting locations of objects in a plane, including emit light beams, one at a time, at locations along a first edge of a detection area, refract each light beam into multiple divergent light beams, direct each of the divergent beams to arrive at a respective pair of focusing lenses mounted along a second edge of the detection area, opposite the first edge, wherein an intensity profile of each divergent beam has maximum intensity along the center of the beam, for each of the focusing lenses, measure an intensity profile of that portion of the divergent beam that enters the focusing lens, for each pair of focusing lenses receiving a single divergent beam, compare the measured intensity profiles for light arriving at each lens, and determine a location of an object that partially blocks at least one of the divergent beams, based on the compares.