Multi-Channel UV Sensor with Integrated Filter and Subtraction Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing UV sensors face challenges in accurately measuring the solar UV spectrum, particularly in the UVB range, due to sensitivity to manufacturing variations and incident light angle, requiring different filtering profiles for each sensor channel and being prone to manufacturing process tolerances.
Innovation Solution
A multi-channel UV sensor is designed with a first photodiode and a second photodiode having different spectral responses, a filter layer with a controlled parameter affecting the second photodiode's response, and a subtraction circuit to provide a differential response targeting specific UV spectra, such as UVA and UVB, reducing the need for external filters and improving tolerance to manufacturing variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional filtering is applied to improve UV wavelength selectivity, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the filtering function with the photodiode structure itself by forming filter layers directly on the photodiode surface during manufacturing. This integration eliminates the need for separate external filters, reducing device complexity while maintaining UV wavelength selectivity. The filter layers are incorporated into the sensor housing or applied at wafer level, combining multiple functions into a unified structure.
Solution Approach 2:
The photodiode structure is designed to serve multiple functions simultaneously: detecting UV wavelengths and providing spectral selectivity through integrated filter layers. This multi-functionality reduces the need for additional components, thereby decreasing device complexity while maintaining measurement precision for different UV bands (UVA, UVB, UVC).
2Measurement precision
If different filtering profiles are applied to each sensor channel, then measurement precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
The filter layers are formed on the photodiodes during the manufacturing process itself, before the sensors are assembled into the final device. This preliminary action ensures that each sensor channel receives its specific filtering profile during fabrication, allowing for precise control of spectral responses while reducing the need for post-assembly adjustments and minimizing manufacturing tolerance challenges.
Solution Approach 2:
The patent controls the spectral filtering characteristics by adjusting parameters of the filter layers, such as thickness, material composition, and optical properties. By modifying these parameters during manufacturing, different filtering profiles are achieved for different sensor channels, enabling precise spectral response control without requiring extremely tight manufacturing tolerances on mechanical filter components.
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 multi-channel UV sensor achieves accurate estimation of solar UV spectra with reduced system complexity and sensitivity to manufacturing variations, enabling precise detection of UV index and other biologically relevant spectrums without requiring contextual data.
Implementation Method 1
a first photodiode with a first UV spectral response and a second photodiode with a second UV spectral response
Implementation Method 2
A filter layer having a graded spectral response is formed over the second photodiode
Implementation Method 3
The subtraction circuit is configured to provide a differential response based on a difference between the first UV spectral response and the second UV spectral response
Data Source
AI summary
The present disclosure describes an ultraviolet (UV) sensor configured to detect a target UV spectrum (e.g., UVB spectrum). The UV sensor includes a first photodiode with a first UV spectral response and a second photodiode with a second UV spectral response. A filter layer having a graded spectral response is formed over the second photodiode, and the second UV spectral response is affected by a controlled parameter (e.g., thickness) of the filter layer. The UV sensor further includes a subtraction circuit coupled with the first photodiode and the second photodiode. The subtraction circuit is configured to provide a differential response based on a difference between the first UV spectral response and the second UV spectral response. The controlled parameter of the filter layer can be selected such that the differential response provides a detected spectral response of the target spectrum.