Ambient Light Sensor Collimator for Directional Light Sensitivity
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Solution Overview
Problem
Ambient light sensors in electronic devices are sensitive to directional light sources, leading to reduced sensitivity due to light diffusers scattering incoming light away from photodetectors, which affects the accuracy of ambient light measurements.
Innovation Solution
An electronic device with an ambient light sensor featuring a light diffuser and a light collimator, where the diffuser uses light-scattering particles or textured structures to diffuse ambient light, and the collimator, with inwardly facing protrusions, collimates the diffused light to direct it onto photodetectors, enhancing sensitivity by concentrating light onto the sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light diffuser is used to reduce sensitivity to directional light sources, then directional light sensitivity is reduced, but ambient light sensor sensitivity decreases due to light scattering away from photodetectors
Solution Approach 1:
A light collimator is introduced as an intermediary component between the light diffuser and the photodetector. The collimator captures scattered light from the diffuser and redirects it toward the photodetector, mediating between the conflicting requirements of diffuse light distribution and focused light detection. This intermediary structure recovers light that would otherwise be scattered away, maintaining sensor sensitivity while preserving the diffuser's ability to reduce directional light sensitivity.
Solution Approach 2:
The light collimator creates localized light concentration zones at the photodetector surface by capturing scattered light in specific angular ranges and redirecting it. This local quality enhancement ensures that while the overall light field remains diffuse (reducing directional sensitivity), sufficient light is concentrated at the detection point to maintain measurement precision.
2Object-affected harmful factors
If a light diffuser scatters incoming light to reduce directional sensitivity, then directional light sensitivity is reduced, but light concentration on photodetectors decreases
Solution Approach 1:
The light collimator serves as a mediator that intercepts scattered light rays from the diffuser and redirects them toward the photodetector. By capturing light in specific angular ranges and refocusing it, the collimator compensates for the light concentration loss caused by diffusion, ensuring adequate illumination intensity reaches the photodetector while maintaining the diffuse light field characteristics.
Solution Approach 2:
The light collimator changes the angular distribution parameter of scattered light by capturing rays at certain angles and redirecting them to concentrate on the photodetector. This parameter transformation converts isotropically scattered light into a more directional beam at the detection point, restoring illumination intensity without creating overall directional sensitivity.
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 combination of light diffuser and collimator improves the sensitivity of ambient light sensors by maintaining light concentration on photodetectors, reducing the impact of directional light sources and enhancing the accuracy of ambient light measurements.
Implementation Method 1
A light diffuser may diffuse incoming ambient light before the ambient light is measured by a photodetector associated with the ambient light sensor. Light diffuser structures may help reduce the sensitivity of an ambient light sensor to sources of directional lighting
Implementation Method 2
Diffused ambient light may be collimated using a light collimator. The light collimator may be interposed between the photodetectors and the light-diffusing layers. The light-collimator may have one or more light-collimating layers. Each light-collimating layer may include a textured light collimating pattern such as inwardly facing protrusions
Implementation Method 3
an ambient light sensor may measure ambient light intensity so that display brightness adjustments may be made to a display in an electronic device
Data Source
AI summary
An electronic device may be provided with a display. The display may have an array of pixels that form an active area and may have an inactive area that runs along an edge of the active area. An opaque layer may be formed on an inner surface of a display cover layer in the inactive area of the display or may be formed on another transparent layer in the electronic device. An ambient light sensor window may be formed from the opening and may be aligned with color ambient light sensor. The ambient light sensor may have an integrated circuit with photodetectors. Ambient light passing through the ambient light sensor window may be diffused by a light diffuser having one or more light-diffusing layers. Diffused ambient light may be collimated using a light collimator having one or more light-collimating layers such as layers with inwardly facing protrusions.