Solid-State Reset Electrometer for Low Leakage Radiation Monitoring
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Solution Overview
Problem
Radiation monitors face significant current leakage issues due to temperature variations, particularly affecting the accuracy of radiation detection, and existing solutions like reed relay devices are bulky and slow.
Innovation Solution
A radiation monitor design featuring an ionization chamber and an electrometer with a controller that operates in multiple modes to minimize current leakage across switches, using capacitors and switches configured to manage current flow effectively across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If FET switch devices are used for resetting capacitors, then the switching speed is fast, but current leakage increases significantly at elevated temperatures
Solution Approach 1:
The patent replaces the conventional FET electronic switch with a solid-state reset mechanism using a capacitor and resistor network that charges and discharges the integration capacitor through controlled current paths. This substitution eliminates the FET switch entirely, thereby eliminating its temperature-dependent leakage issue while maintaining the reset function through passive components that are less sensitive to temperature variations.
Solution Approach 2:
The patent changes the operating parameters by using a dual-capacitor system where the first capacitor (C1) and second capacitor (C2) work together to manage the reset process. The resistor R1 and R2 are configured to provide controlled charging and discharging paths. This parameter change allows the system to achieve both fast switching and low leakage by distributing the electrical stress across multiple components with different temperature characteristics.
2Object-generated harmful factors
If reed relay devices are used to avoid current leakage, then current leakage is minimized, but device size and switching speed worsen
Solution Approach 1:
The patent replaces the mechanical reed relay device with a solid-state capacitor-based reset circuit. This substitution eliminates the need for bulky mechanical components while maintaining low leakage characteristics. The solid-state components (capacitors and resistors) are inherently smaller and faster than mechanical reed relays, resolving the contradiction between leakage minimization and device compactness.
Solution Approach 2:
The patent extracts the switching function from the mechanical reed relay and implements it through the capacitor charging and discharging cycles. By taking out the mechanical switching component and replacing it with electrical field-based operation, the system achieves both small size and low leakage simultaneously.
3Adaptability or versatility
If FET switches are used across wide temperature ranges, then switching functionality is maintained, but measurement precision deteriorates due to leakage variation
Solution Approach 1:
The patent substitutes the FET switch with a temperature-stable passive reset circuit using capacitors and resistors. These passive components have more stable electrical characteristics across temperature ranges compared to active FET devices. The capacitor C1 and C2, along with resistors R1 and R2, provide a reset mechanism that maintains consistent performance from -40°C to +85°C, thereby preserving measurement precision across wide temperature ranges.
Solution Approach 2:
The patent incorporates feedback mechanisms and carefully designed RC time constants that compensate for temperature effects before they can significantly impact measurement precision. The dual-capacitor system with configured resistors provides a buffered reset that anticipates and mitigates temperature-driven drift, maintaining stable performance across the operating temperature range.
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 ensures accurate and low current leakage measurements across a broad temperature range, from 35° to 60° Celsius, enhancing the reliability of radiation detection without the bulkiness of reed relay devices.
Implementation Method 1
An ionization chamber for detecting radiation that passes into the ionization chamber. The ionization chamber generates a current flow in response to the detected radiation.
Implementation Method 2
An electrometer is electrically connected to the ionization chamber for measuring the current flow generated by the ionization chamber
Data Source
AI summary
A radiation monitor includes an ionization chamber for detecting radiation that passes into the ionization chamber. The ionization chamber generates a current flow in response to the detected radiation. An electrometer is electrically connected to the ionization chamber for measuring the current flow generated by the ionization chamber. The electrometer is operable in a plurality of modes based on a magnitude of the current flow generated by the ionization chamber. A method of measuring current flow through an electrometer of a radiation monitor is also provided.