Light Guide Diffractive Structures Touch Location Detection
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Solution Overview
Problem
Existing input devices, such as touch pads, face challenges in being cost-effective and easy to mass-produce while accurately sensing touch locations on their surface.
Innovation Solution
A light guide with diffractive structures on its surface and a slanted facet, coupled with an optical sensing module, where the diffractive structures diffract light beams to determine the location of an object based on the exiting angle and light intensity changes, allowing for precise detection of touch positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional touch pad technologies are used, then touch location sensing can be achieved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent replaces complex mechanical/electronic sensing mechanisms with an optical system. A light source illuminates the touch surface, and optical sensors detect light reflections or transmissions to determine touch locations. This substitution of mechanical sensing with optical fields simplifies the overall device structure while maintaining or improving detection accuracy.
Solution Approach 2:
The patent utilizes changes in optical parameters (light intensity, angle, polarization) to encode touch location information. By measuring variations in these optical parameters rather than relying on complex mechanical displacement sensors, the system achieves precise location detection with simpler device architecture.
2Measurement precision
If conventional touch pad technologies are used, then touch location sensing can be achieved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive mechanical sensing components with cost-effective optical elements. Standard light sources and optical sensors can be mass-produced at lower costs than specialized mechanical touch sensors, while achieving comparable or superior location detection accuracy.
Solution Approach 2:
The optical sensing system can detect multiple touch locations simultaneously using a single light source and sensor array, whereas conventional systems often require multiple separate sensing elements. This multi-functionality reduces component count and manufacturing complexity.
3Ease of manufacture
If simple optical structures are used, then manufacturing cost decreases, but measurement precision deteriorates
Solution Approach 1:
The patent introduces angular dimension to the optical measurement. Instead of only measuring light intensity in one dimension, the system measures both intensity and angle of light reflections or transmissions. This additional dimensional information enables precise location determination using simple optical components without sacrificing measurement accuracy.
Solution Approach 2:
The optical sensing area is divided into multiple detection zones or pixels, each capable of independent measurement. This segmentation allows the system to achieve high overall measurement precision through multiple simple measurement points rather than requiring a single complex precision sensor.
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
Enables inexpensive and efficient mass production of input devices that can accurately determine touch locations by correlating light beam angles and intensity changes, facilitating user input and image processing.
Implementation Method 1
The diffractive structures have concentric fringes centered near the slanted facet. Fringes are arranged such that a light beam directed from the first surface at a location P toward the second surface is diffracted by the fringes only if the beam encounters the diffractive structures substantially at a predefined direction.
Data Source
AI summary
A light guide has a first surface and a second surface with diffractive structures. A slanted facet is provided at one corner of the light guide. The diffractive structures have concentric fringes centered near the slanted facet. Fringes are arranged such that a light beam directed from the first surface at a location P toward the second surface is diffracted by the fringes only if the beam encounters the diffractive structures at a certain direction. The diffracted beam is guided and exits through the slanted surface at an exiting angle, which is correlated to the location P. If the light guide is illuminated in such a way that when an object is present at the first surface, it changes the light intensity of the exiting light beam. By detecting the exiting angle and the change of light intensity, the location of the object can be determined.