Infrared Sensor Absorber and Shielding Film Design
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Solution Overview
Problem
Conventional wavelength selective thermal type infrared sensors face complexity, reduced detection efficiency due to light absorption by optical filters, and sensitivity issues due to light incidence angles, as well as absorption of unwanted wavelengths by side surfaces and support legs.
Innovation Solution
A thermal type infrared sensor with an absorber formed on the detector to selectively absorb infrared light of a specific wavelength, using a cap with a shielding film and window to direct incoming light rays onto the absorber, preventing absorption by side surfaces and support legs, and arranged in a matrix format for multiple wavelength detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an optical filter is provided on an infrared detector to detect specific wavelength infrared light, then wavelength selectivity is improved, but the structure becomes complex and detection efficiency decreases
Solution Approach 1:
The patent combines the optical filter function with the infrared detector by forming an absorber layer directly on the detector surface. This integration eliminates the need for a separate optical filter component, thereby reducing structural complexity while maintaining wavelength selectivity through the absorber's selective absorption characteristics
Solution Approach 2:
The patent employs composite material structures, specifically combining the infrared detector material with an absorber layer having specific optical properties. This composite structure enables the detector to selectively absorb specific wavelength infrared light while maintaining structural simplicity
2Adaptability or versatility
If an optical filter is used to achieve wavelength selectivity, then specific wavelength detection is improved, but detection efficiency decreases due to light absorption by the filter
Solution Approach 1:
The patent extracts the filtering function from a separate optical filter component and integrates it directly into the detector structure. This eliminates the intermediate transmission step where energy loss occurs, allowing the detector to directly absorb specific wavelength infrared light without energy loss through filter transmission
Solution Approach 2:
The patent converts the previously harmful effect of light absorption by optical filters into a beneficial direct absorption mechanism. By forming an absorber layer on the detector, the light absorption that was previously a loss mechanism in filters becomes the primary detection mechanism, improving overall detection efficiency
3Loss of energy
If a thermal type infrared sensor with periodic structure is used to increase absorption, then specific wavelength absorption is improved, but sensitivity decreases due to absorption of unwanted wavelengths by side surfaces and support legs
Solution Approach 1:
The patent applies local quality by creating an absorber layer with specific properties only in the active detection region of the infrared detector. This localized absorber structure ensures that only the desired wavelength is absorbed at the detection site, while side surfaces and support legs without the absorber layer do not absorb unwanted wavelengths, thereby maintaining sensitivity
4Adaptability or versatility
If multiple optical sensors with different wavelength transparency are provided to detect multiple infrared wavelengths, then detection versatility is improved, but device complexity increases
Solution Approach 1:
The patent implements multi-functionality by designing a single infrared detector with an absorber layer that can detect multiple infrared wavelengths. By adjusting the absorber layer's properties or configuration, the same detector structure can be tuned to detect different wavelengths, eliminating the need for multiple specialized sensors
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 design enhances sensitivity and signal-to-noise ratio by ensuring only the desired wavelength is absorbed, reducing noise from unwanted wavelengths and simplifying the structure, while maintaining high detection efficiency independent of light incidence angles.
Implementation Method 1
an absorber formed on the thermal detector which is configured to absorb infrared light rays of a specific wavelength... The thermal type infrared sensor includes a periodically repeating structure on an infrared detector for generating plasmon resonance of infrared light rays of a specific wavelength
Implementation Method 2
a shielding film, with a window formed therein, provided on at least one of the front and rear surfaces of the body, wherein the infrared light rays are reflected on the shielding film other than the portion of the window
Data Source
AI summary
An infrared sensor includes: a package; an infrared detecting element formed on the package, the infrared detecting element including a thermal detector and an absorber formed on the thermal detector which is configured to absorb infrared light rays of a specific wavelength that are detected by conversion of the infrared light rays into heat; and a cap formed on the package to cover the infrared detecting element, the cap including: a body having front and rear surfaces, through which the infrared light rays transmit; and a shielding film, with a window formed therein, provided on at least one of the front and rear surfaces of the body, the infrared light rays being reflected by the shielding film other than a portion of the shielding film having the window, and every one of the infrared light rays passing through the window of the cap impinging on the absorber.