Polarized Ambient Light Sensor for Display Noise Reduction
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Solution Overview
Problem
Incorporating ambient light sensors into electronic devices is challenging due to space constraints and potential interference from other components, which affects their accuracy in measuring ambient light.
Innovation Solution
The use of optical structures such as wave plates and polarizers in ambient light sensors to differentiate between ambient light and emitted display light, allowing for accurate measurements by configuring the sensors to prevent ambient light from reaching one detector while allowing it to reach another, and processing the outputs to remove noise contributions from display light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical structures such as wave plates and polarizers are added to the ambient light sensor, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The ambient light sensor is divided into multiple light detectors (first light detector and second light detector), each equipped with specific optical structures. This segmentation allows different detectors to measure different components of light (ambient vs. display light), improving measurement precision while distributing the complexity across multiple simpler detector units
Solution Approach 2:
Optical structures (wave plates and polarizers) are introduced as intermediary components between the light sources and light detectors. These intermediaries manipulate the polarization state of light to enable differentiation between ambient light and display light, achieving high measurement precision without requiring complex direct detection mechanisms
2Area of stationary object
If the ambient light sensor is placed closer to the display, then space is saved, but harmful factors increase due to interference from display light
Solution Approach 1:
The display light, which was previously a harmful interference factor, is converted into a beneficial signal source. By using polarizers and wave plates, the sensor can distinguish between polarized display light and unpolarized ambient light, allowing the sensor to be placed close to the display without sacrificing measurement accuracy
Solution Approach 2:
Different optical structures with specific polarization properties are applied to different light detectors. The first light detector is equipped with optical structures that block polarized display light, while the second light detector uses structures that allow it through, enabling localized differentiation of light sources in close proximity
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 accuracy of ambient light measurements, reducing noise interference and allowing for dynamic adjustments to display brightness and color based on ambient light conditions, thereby improving the overall performance of electronic devices.
Implementation Method 1
the optical structures of the ambient light sensor are configured to prevent ambient light from reaching a first of the light detectors while allowing ambient light to reach a second of the light detectors
Data Source
AI summary
An electronic device may be provided with an ambient light sensor. The ambient light sensor may be a color ambient light sensor or a monochrome ambient light sensor. The electronic device may have a light-emitting component such as a display. During operation of the display, the display emits light. To reduce noise due to the emitted light while measuring ambient light, the ambient light sensor may have optical structures such as wave plates and polarizers. Theses optical structures may overlap light detectors. The optical structures may be configured to prevent ambient light from reaching a first of the light detectors while allowing ambient light to reach a second of the light detectors. The ambient light sensor may be configured to receive ambient light that has passed thorough an inactive area of a display or that has passed through a pixel array in an active area of a display.