Textured Wave Guide for Ambient Light Sensor Angular Response
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Solution Overview
Problem
Ambient light sensors in flat panel displays struggle to accurately detect ambient light intensity from varying angles, leading to suboptimal display visibility and power consumption due to the limitations in angular response of existing wave guides.
Innovation Solution
A wave guide with a textured surface, featuring geometric structures such as trapeziums, partial-spheroids, or four-sided pyramids, is integrated between the window and light sensor, configured to guide ambient light and ensure that the intensity striking the sensor varies proportionally with the cosine of the angle of incidence, ensuring light is directed normally to the sensor regardless of incidence angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional wave guide is used in the ambient light sensor, then the device structure is simple, but the angular response is poor leading to inaccurate light intensity detection
Solution Approach 1:
The wave guide surface is divided into multiple local regions with different geometric structures (pyramids, prisms, gratings) that have different light-guiding properties. Each local region is optimized to handle light from specific angles, collectively achieving wide-angle accurate detection without requiring complex overall restructuring
Solution Approach 2:
The invention transitions from a flat two-dimensional wave guide surface to a three-dimensional structured surface with geometric features having specific heights, angles, and spatial arrangements. This dimensional enhancement enables the wave guide to manipulate light paths from different angles more effectively, improving angular response
2Adaptability or versatility
If the wave guide is designed to capture light from wide angles, then the angular response improves, but the structural complexity and manufacturing difficulty increase
Solution Approach 1:
The wave guide surface is segmented into multiple discrete geometric structures (pyramids, prisms, gratings) that can be independently designed and manufactured. This segmentation allows for modular fabrication approaches and simplifies the manufacturing process compared to creating a monolithic complex structure
Solution Approach 2:
The invention uses systematic variation of geometric parameters (height, base size, angle, spacing) of the surface structures to achieve different light-guiding functions. By changing these parameters, the same basic structure type can be optimized for different angular ranges, simplifying manufacturing while maintaining versatility
3Measurement precision
If the light sensor is positioned to receive direct normal light, then detection accuracy is high, but the sensor cannot effectively detect light from oblique angles
Solution Approach 1:
The structured wave guide surface acts as an intermediary between the ambient light and the light sensor. It receives light from various angles and transforms it into directed paths that all converge on the sensor, enabling the sensor to accurately detect oblique light without needing to physically reposition
Solution Approach 2:
The wave guide structures employ curved or angled surfaces (pyramidal faces, prismatic surfaces) that naturally redirect light rays through refraction and reflection. These curved geometries are effective at capturing and redirecting light from a wide range of incident angles onto the sensor surface
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 angular response of ambient light sensors, improving display visibility and power management by accurately measuring ambient light intensity across different angles, thereby optimizing display brightness adjustments.
Implementation Method 1
a wave guide comprising a textured surface disposed between the window and the light sensor; the textured surface having a geometric structure; the geometric structure configured according to a material and a thicknesses of the window
Implementation Method 2
the geometric structure further configured to guide ambient light travelling through the window onto the light sensor such that an intensity of ambient light that strikes the sensor varies substantially proportionally according to a function comprising a cosine of an angle of incidence
Data Source
AI summary
Electronic displays encounter visibility issues due to varying ambient light conditions. An ambient light sensor can be provided to sense ambient light and dynamically adjust display brightness to compensate for changes in ambient light. A wave guide for improving angular response in a light sensor is provided.