Infrared Detector Vacuum Pressure Measurement via Heated Heat Shield
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Solution Overview
Problem
Infrared detectors within vacuum packages experience a gradual loss of vacuum pressure due to factors like outgassing and leaks, leading to reduced sensitivity and performance over time, necessitating a method to accurately measure vacuum pressure levels.
Innovation Solution
A device comprising an infrared detector thermally isolated from a substrate, coupled with a heat shield that blocks external thermal radiation and is heated to a specific temperature to detect changes in resistance related to vacuum pressure, allowing for the determination of vacuum pressure levels based on output signals and calibration information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the infrared detector is placed within a vacuum package to minimize thermal conduction, then thermal isolation performance is improved, but vacuum pressure degradation over time reduces measurement precision
Solution Approach 1:
The patent applies preliminary action by incorporating a vacuum pressure sensor and heat shield into the vacuum package assembly during manufacturing, before the device is deployed. This allows for continuous monitoring of vacuum pressure levels and proactive detection of degradation, enabling maintenance or recalibration before performance is significantly impacted. The heat shield is pre-positioned to block thermal radiation paths that could interfere with pressure measurements.
Solution Approach 2:
The patent uses a heat shield as an intermediary component between external thermal radiation sources and the infrared detector. This heat shield blocks thermal radiation from reaching the detector directly, preventing thermal conduction interference that would otherwise compromise the accuracy of vacuum pressure measurements. The intermediary structure isolates the measurement system from harmful thermal effects while maintaining vacuum integrity.
2Reliability
If the vacuum package is sealed to maintain vacuum integrity, then thermal isolation is improved, but outgassing and leaks cause gradual pressure loss reducing detector sensitivity
Solution Approach 1:
The patent implements feedback by continuously monitoring vacuum pressure levels using an integrated sensor within the vacuum package. The sensor provides real-time data on pressure changes caused by outgassing or leaks, allowing the system to detect degradation trends. This feedback mechanism enables proactive maintenance scheduling and ensures the vacuum package remains within operational parameters, maintaining both reliability and pressure integrity.
3Temperature
If thermal radiation blocking is enhanced to protect the infrared detector, then thermal isolation is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the heat shield to serve multiple functions simultaneously: it blocks thermal radiation from reaching the infrared detector, provides structural support within the vacuum package, and acts as a reference element for pressure sensing. By combining these functions into a single component, the design enhances thermal isolation without proportionally increasing device complexity.
Solution Approach 2:
The patent merges the vacuum pressure sensor mounting structure with the heat shield structure, combining two functional elements into an integrated assembly. The sensor is mounted directly to the heat shield, which itself is positioned within the vacuum package to block thermal radiation. This merging reduces the number of separate components and simplifies the overall device architecture while maintaining effective thermal blocking.
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 solution enables precise measurement of vacuum pressure, helping to maintain the integrity of the vacuum package and the performance of infrared detectors, thereby extending the operational lifespan of infrared cameras.
Implementation Method 1
The heat shield is configured to receive a current through the contacts to heat the heat shield to a first temperature
Implementation Method 2
The change in resistance of each infrared detector is translated into a time-multiplexed electrical signal by circuitry known as the read out integrated circuit (ROIC)
Implementation Method 3
an infrared detector may be encapsulated within a vacuum package to minimize thermal conduction via gas molecules
Data Source
AI summary
A device is disclosed including a substrate; an infrared detector coupled to and thermally isolated from the substrate; and a heat shield coupled to the substrate by a plurality of contacts, the heat shield disposed above the infrared detector to block external thermal radiation from being received by the infrared detector. The heat shield is configured to receive a current through the contacts to heat the heat shield to a first temperature, and the infrared detector is configured to detect the first temperature and provide an output signal that is related to a vacuum pressure within the device. Methods for using and forming the device are also disclosed.