Diplexer-Based Dual-Mode Fill Level Sensor Circuit
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Solution Overview
Problem
Existing medium-contacting fill-level measuring devices face challenges in achieving optimized accuracy and reliability due to the presence of semiconductor components near the measuring probe, which require protection against electrostatic discharges and additional control lines for switching between capacitive and travel-time measurement circuits.
Innovation Solution
The use of a diplexer to separate high-frequency and low-frequency measurement signals, employing highpass and lowpass filters made of passive components like capacitors and coils, eliminates the need for semiconductor components and additional control lines, allowing for simultaneous or alternate operation of capacitive and time-domain reflectometer measurement circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If semiconductor components are used for switching between capacitive and travel-time measurement circuits, then measurement functionality is achieved, but protection against electrostatic discharges and additional control lines are required
Solution Approach 1:
The patent removes semiconductor switching components from the measurement circuit by extracting the switching function entirely. Instead of using electronic switches, the system employs passive diplexer components that naturally route signals based on frequency, eliminating the need for active semiconductor devices and their associated protection circuits.
Solution Approach 2:
The diplexer acts as an intermediary component that mediates between the single measuring probe and the two different measurement circuits. It separates the high-frequency travel-time signals from the low-frequency capacitive signals without requiring active switching, thus avoiding semiconductor components while maintaining adaptability.
2Adaptability or versatility
If switching between capacitive and travel-time measurement circuits is implemented, then different measurement methods are available, but additional control lines are required
Solution Approach 1:
The system maintains continuous operation of both measurement circuits simultaneously through the diplexer, which continuously routes appropriate frequencies to the correct circuits. This eliminates the need for switching control lines while preserving the ability to use either or both measurement methods.
Solution Approach 2:
The diplexer provides multi-functionality by handling both capacitive and travel-time measurement signals through a single component. It universally routes different frequency signals to appropriate circuits without requiring separate control mechanisms for each measurement type.
3Device complexity
If semiconductor components are placed near the measuring probe, then signal processing is simplified, but protection against electrostatic discharges is required
Solution Approach 1:
The patent replaces expensive and fragile semiconductor components with inexpensive passive diplexer components that have no moving parts or sensitive elements. These passive components are inherently resistant to electrostatic discharge, eliminating reliability concerns while maintaining signal processing capability.
Solution Approach 2:
The patent substitutes electronic semiconductor switching with passive frequency-based signal routing using diplexers. This replacement eliminates the need for electrostatic protection while maintaining the ability to separate and process different measurement signals efficiently.
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 enhances measurement accuracy and reliability by reducing cross-sensitivity to environmental influences and noise, while eliminating the need for complex protection against electrostatic discharges and additional control signals, thereby improving the robustness of the sensor output.
Implementation Method 1
The use of a diplexer to separate high-frequency and low-frequency measurement signals, employing highpass and lowpass filters made of passive components like capacitors and coils
Implementation Method 2
a time domain reflectometer-measurement circuit, which produces a high-frequency, electromagnetic measurement signal sent out as a sent signal via the measuring probe, which receives a reflection signal as an echo, and which through a time difference between the sending of the sent signal and the reception of the reflection signal ascertains a travel time
Implementation Method 3
a capacitive measurement circuit, which produces a low-frequency measurement signal on the measuring probe and thereby ascertains the capacitance or a reactance
Implementation Method 4
through a time difference between the sending of the high-frequency pulse and the receipt of the reflected echo signal of the medium. The fill-level can be ascertained from the time difference
Data Source
AI summary
An apparatus for ascertaining and/or monitoring at least one fill-level of at least one medium in a container according to a travel-time measuring method and/or a capacitive measuring method by means of at least one measuring probe. A capacitive measurement circuit, which produces a low frequency measurement signal on the measuring probe, a time-domain reflectometer measurement circuit, which produces a high frequency, electromagnetic signal sent out as a sent signal and a control/evaluation unit, which controls both measurement circuits are included. Also included is a diplexer, which sends the low-frequency measurement signal and the high-frequency, electromagnetic measurement signal to the measuring probe and effects a signal separation of the high-frequency, electromagnetic measurement signal into the first signal path of the time-domain reflectometer measurement circuit and the low-frequency measurement signal into the second signal path of the capacitive measurement circuit.