Monolithic UV and IR Flame Detector with SiC Photodiode
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Solution Overview
Problem
Current flame sensors are bulky, costly, and prone to false alarms due to sensitivity to spurious ultraviolet radiation and low infrared sensitivity, requiring high voltages and being limited by dust and smoke attenuation.
Innovation Solution
A semiconductor device with a photodiode configuration for ultraviolet detection and a resistive region for infrared detection, integrated into a compact monolithic sensor using silicon carbide, featuring a Geiger-mode avalanche photodiode and a microbolometer-like infrared sensor with a bridge structure for thermal insulation, and an optical filter to block spurious radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gas photomultiplier tubes are used for ultraviolet detection, then sensitivity to weak ultraviolet radiation is improved, but device dimensions and cost increase
Solution Approach 1:
The patent uses a silicon carbide photodiode as a solid-state copy alternative to the gas photomultiplier tube, replicating its ultraviolet detection function while achieving miniaturization and cost reduction through semiconductor fabrication techniques
Solution Approach 2:
The patent replaces the mechanical/gas-based photomultiplier tube system with a solid-state semiconductor photodiode system, eliminating the need for high voltage tubes and complex mechanical structures while maintaining detection sensitivity
2Volume of moving object
If solid-state ultraviolet detectors are used, then device dimensions are reduced, but sensitivity to spurious ultraviolet radiation increases
Solution Approach 1:
The patent applies an optical filter with specific spectral characteristics to the photodiode, creating local quality enhancement that selectively transmits flame-related ultraviolet wavelengths while blocking spurious radiation from sunlight and arc lamps
Solution Approach 2:
The patent introduces an optical filter as an intermediary element between the environment and the photodiode, which mediates the radiation interaction by selectively allowing desired wavelengths to reach the detector while blocking unwanted radiation
3Speed
If infrared sensors are used for flame detection, then detection range is extended, but false alarms increase due to sensitivity to non-flame infrared sources
Solution Approach 1:
The patent merges ultraviolet and infrared detection capabilities into a single integrated sensor system, combining the advantages of both detection modes to achieve reliable flame detection with extended range while using the complementary nature of dual-wavelength detection to reduce false alarms
Solution Approach 2:
The patent implements signal processing that analyzes the correlation between ultraviolet and infrared signals, using feedback mechanisms to distinguish true flame events from spurious infrared sources by requiring consistent detection across both wavelength ranges
4Reliability
If combined ultraviolet and infrared sensors are used, then flame detection reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the ultraviolet photodiode and infrared detector into a single integrated sensor device with shared structural components and packaging, reducing overall device complexity while maintaining the reliability benefits of dual-wavelength detection
Solution Approach 2:
The patent creates a universal sensor platform that performs both ultraviolet and infrared detection functions within a single device structure, eliminating the need for separate sensor systems and reducing overall system 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
The solution provides a compact, cost-effective, and sensitive flame detection system with reduced false alarms, operating at lower voltages and capable of detecting ultraviolet and infrared radiation efficiently, even in harsh environments, without the need for gas photomultiplier tubes.
Implementation Method 1
a junction of a photodiode configured to detect ultraviolet radiation emitted by the flames
Implementation Method 2
a sensitive region arranged on the supporting dielectric region and configured to have a resistance that varies as a function of infrared radiation emitted by the flames
Data Source
AI summary
A semiconductor device for flame detection, including: a semiconductor body having a first conductivity type conductivity, delimited by a front surface and forming a cathode region; an anode region having a second conductivity type conductivity, which extends within the semiconductor body, starting from the front surface, and forms, together with the cathode region, the junction of a photodiode that detect ultraviolet radiation emitted by the flames; a supporting dielectric region; and a sensitive region, which is arranged on the supporting dielectric region and varies its own resistance as a function of the infrared radiation emitted by the flames.