Multi-Cavity Fabry-Perot Filter for Ambient Light Sensing
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Solution Overview
Problem
Conventional ambient light sensors have a non-ideal spectral response that includes infrared light, leading to unnecessary backlight power consumption and inconsistency with human eye perception, as they detect visible and non-visible light beyond the human eye's range.
Innovation Solution
A multi-cavity Fabry-Perot ambient light filter structure with partially reflective layers and interferometric layers is used to block infrared light between 700 nm and 1100 nm, matching the human eye's spectral response and reducing power consumption by effectively filtering out non-visible light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ambient light sensor is used, then the sensor can detect ambient light brightness, but the sensor spectral response includes infrared light which causes unnecessary backlight power consumption
Solution Approach 1:
The patent extracts and removes the harmful infrared component from the ambient light spectrum by introducing a multi-cavity Fabry-Perot filter structure. This filter selectively transmits only the visible spectrum (380-780 nm) while blocking infrared wavelengths, thereby extracting the useful visible light information while eliminating the harmful IR component that causes unnecessary power consumption.
Solution Approach 2:
The multi-cavity Fabry-Perot filter acts as an intermediary component between the ambient light source and the photodiode sensor. This intermediary structure modifies the spectral composition of light reaching the sensor, allowing only desired visible wavelengths to pass through while blocking infrared, thus mediating the interaction between light and sensor to achieve spectral matching.
2Measurement precision
If conventional ambient light sensor is used, then the sensor detects ambient light, but the sensor responds to non-visible infrared light that human eye is unable to respond
Solution Approach 1:
The patent extracts only the visible spectrum portion (380-780 nm) from the ambient light that reaches the sensor, removing the infrared component. This extraction ensures that the sensor measures only the light wavelengths that human eyes can perceive, thereby aligning the sensor's measurement with human photometric response and eliminating inconsistent brightness perception.
Solution Approach 2:
The multi-cavity Fabry-Perot filter implements local quality by having different transmission characteristics for different wavelength ranges. The filter is designed with specific cavity dimensions and layer structures that provide high transmission in the visible spectrum while providing strong blocking in the infrared region, thereby creating wavelength-dependent local quality in the optical path.
3Object-affected harmful factors
If multi-cavity Fabry-Perot filter structure is used to block infrared light, then infrared blocking performance is improved, but the device structure becomes more complex
Solution Approach 1:
The patent divides the filtering function into multiple independent Fabry-Perot cavities, each designed to block specific infrared wavelength ranges. By segmenting the overall filtering task into multiple specialized cavities (e.g., first cavity for 780-900 nm, second cavity for 900-1100 nm), the system achieves comprehensive infrared blocking while maintaining modular design that simplifies analysis and manufacturing of each individual cavity.
Solution Approach 2:
The patent employs a nested structure where multiple Fabry-Perot cavities are stacked or arranged in sequence, with each cavity nested within the optical path of the previous one. This nesting approach allows multiple filtering functions to be combined in a compact configuration, achieving broad infrared blocking coverage without requiring excessive space or complex lateral arrangement.
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 solution achieves excellent infrared blocking with less than 2% transmittance in the IR range, aligning the sensor's response with human eye sensitivity and reducing power consumption by accurately sensing visible light brightness and color components.
Implementation Method 1
this invention provides a multi-cavity Fabry-Perot filter structure utilizing the Fabry-Perot optical interference theory in order to effectively block the range from 700 nm to 1100 nm
Implementation Method 2
utilizing the Fabry-Perot optical interference theory
Implementation Method 3
an array of photodiode elements to detect and convert the ambient light into electrical signal
Data Source
AI summary
The present invention provides a multi-cavity Fabry-Perot ambient light filter apparatus. The multi-cavity Fabry-Perot ambient light filter apparatus comprises a plurality of Fabry-Perot cavities, each of the plurality of Fabry-Perot cavities covering one of a plurality of photodiodes; wherein each of the plurality of Fabry-Perot cavities has two partially reflective layers and one interferometric layer sandwiching between the two partially reflective layers, and shares one of the two partially reflective layers with a neighboring Fabry-Perot cavity and thereby stair stacking with the neighboring Fabry-Perot cavity. The plurality of Fabry-Perot cavities are capable of blocking the ambient light except for a wavelength spectrum that is recognizable for human eyes, thereby effectively accomplishes excellent IR blocking from non-visible light spectra.