Ambient Light Sensor Shadow Correction via Multi-Spectral Photodiode Arrays
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Solution Overview
Problem
Ambient light sensors in devices, such as smartphones and laptops, face inaccuracies in detecting lighting conditions due to shadowing effects caused by incident light angles, leading to improper display brightness adjustments, especially in bright or dark environments.
Innovation Solution
The implementation of a method using a combination of photodiode arrays that detect visible and infrared light, with weighting factors to subtract infrared contributions, and a process to detect and correct for shadowing by calculating an artificial illuminance value when shadowing is detected, ensuring accurate illuminance determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ambient light sensors are disposed within the device to detect lighting conditions, then the display brightness can be adjusted based on detected illuminance, but shadowing effects from incident light angles introduce errors into the illuminance determination
Solution Approach 1:
The sensor is divided into multiple photodiode arrays with different spectral sensitivities (visible light photodiodes and infrared photodiodes). By segmenting the sensing function across different photodiode types and combining their outputs with appropriate weighting factors, the system can distinguish between visible illuminance and infrared interference, thereby compensating for shadowing effects and improving measurement accuracy.
2Use of energy by moving object
If the display brightness is adjusted based on detected lighting conditions, then power usage can be minimized and readability improved, but inaccurate illuminance detection causes the display to be improperly adjusted (too dark or too bright)
Solution Approach 1:
The system continuously monitors lighting conditions using the multi-photodiode sensor and dynamically adjusts display brightness based on the calculated illuminance. The feedback loop uses weighted combinations of visible and infrared photodiode signals to accurately determine lighting conditions, enabling the display to adapt to changing environments while minimizing power consumption and maintaining optimal readability.
3Measurement precision
If photodiode arrays detecting visible and infrared light are used with weighting factors to subtract infrared contributions, then accurate illuminance can be determined, but device complexity increases
Solution Approach 1:
The patent combines visible light photodiodes and infrared photodiodes into a single integrated sensor assembly. By merging these different photodiode types and processing their outputs together using weighted combinations, the system achieves accurate illuminance measurement that compensates for infrared interference, while the integrated design minimizes 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
This approach enhances the accuracy of lighting condition detection, preventing display brightness from being overly dim or overly bright, thereby improving user experience and minimizing power usage by accurately adjusting display settings.
Implementation Method 1
ambient light sensors comprise arrays of photodiodes that detect visible and infrared light (IR), and photodiodes that detect only IR light
Data Source
AI summary
A device and method for detecting lighting conditions to enable brightness control of a display are disclosed. The device includes a display and a first photodiode array to detect light in a visible spectrum and a non-visible spectrum that is incident on the first photodiode array. The device also includes a second photodiode array to detect light in the non-visible spectrum that is incident on the second photodiode array, and a processor to determine the lighting conditions based on a first output of the first photodiode array and a second output of the second photodiode array. The processor adjusts the first output used to determine the lighting conditions based on detecting that the first photodiode array includes a shadowed region, and controls the brightness of the display based on the lighting conditions.