Angularly-Selective Layer for Touch Detection Accuracy
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Solution Overview
Problem
Horizontally-oriented touch-sensitive display systems face challenges in accurately detecting touch inputs due to forces from objects like drinking glasses and forceful touches, which can lead to diffuse reflection of light and impact the modulation transfer function of the detection system.
Innovation Solution
Incorporating an angularly-selective layer between the display surface and the sensor layer, which transmits light within a specific range of incidence angles and reflects light at higher angles, to improve touch detection accuracy by reducing diffuse light reflection and enhancing the modulation transfer function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a horizontally-oriented touch-sensitive display system is used, then the display can be viewed and interacted with in a horizontal orientation, but the system becomes subject to forces from objects like drinking glasses and forceful touches that cause diffuse light reflection and degrade touch detection accuracy
Solution Approach 1:
An angularly-selective layer is introduced as an intermediary component between the display surface and the sensor layer. This layer selectively transmits light based on its angle of incidence, acting as a mediator that filters out diffuse reflections from objects like glasses while allowing direct touch reflections to reach the sensors, thereby improving touch detection accuracy without changing the horizontal orientation of the display
Solution Approach 2:
The angularly-selective layer imparts different optical properties to different regions of light based on their direction of arrival. It allows light within a specific angular range (relative to the surface normal) to pass through while blocking light at higher angles, creating local quality differentiation in the optical path that selectively enhances touch detection while maintaining the horizontal display orientation
2Measurement precision
If an angularly-selective layer is added to reduce diffuse reflection and improve touch detection, then measurement precision improves, but device complexity increases
Solution Approach 1:
The angularly-selective layer utilizes changes in the angular parameter of incident light to achieve selective transmission and reflection. By designing the layer to respond to specific angular ranges rather than adding complex mechanical or electronic filtering systems, the patent improves measurement precision through a relatively simple optical parameter-based mechanism, minimizing the increase in device complexity
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
The angularly-selective layer effectively transmits light at acceptable angles while reflecting light at higher angles, improving the accuracy of touch detection and reducing the impact of diffuse reflections, thereby enhancing the overall performance of the touch-sensitive display system.
Implementation Method 1
the angularly-selective layer is configured to transmit light having a first range of incidence angles with the surface normal of the angularly-selective layer and to reflect light having a second range of incidence angles that is greater than the first range of incidence angles
Data Source
AI summary
A display system configured for multi-touch input is provided. The display system comprises a display surface, a local light source to illuminate the display surface with infrared light, and an image-producing display panel. The image-producing display panel comprises a plurality of image sensor pixels positioned within a sensor layer of the image-producing display panel. The image-producing display panel further comprises an angularly-selective layer positioned between the display surface and the sensor layer, wherein the angularly-selective layer is configured to transmit light having a first range of incidence angles with the surface normal of the angularly-selective layer to a first sensor pixel of sensor layer, and to reflect light having a second range of incidence angles from a second sensor pixel of the sensor layer, where the second range is greater than the first range of incidence angles with respect to a surface normal of the sensor layer.