Programmable Zener Input Circuit for Wide Voltage Thresholds
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Solution Overview
Problem
Existing input circuits for digital control systems are limited in their ability to adapt to a wide range of voltage levels, particularly in industrial settings where sensors generate signals from extra-low voltage to low voltage, and cannot easily set multiple switching thresholds across these ranges.
Innovation Solution
A large-range input circuit incorporating a series circuit with a rectifier, current regulator, reverse-biased Zener diodes, and an optocoupler, where Zener diodes can be selectively bridged or disabled by a microprocessor to adjust switching thresholds across the range of extra-low voltage signals (≦120 V) and low voltage signals (<1500 V).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single Zener diode is used as a blocking element, then the circuit structure is simple, but only one switching threshold can be implemented
Solution Approach 1:
The patent divides a single Zener diode function into multiple segments by using several Zener diodes (first Zener diode with 3.3V breakdown voltage, second Zener diode with 6.8V breakdown voltage, third Zener diode with 10V breakdown voltage) connected in parallel, each providing a different switching threshold. This segmentation allows the circuit to handle multiple voltage ranges while maintaining relatively simple individual component structures.
Solution Approach 2:
The patent makes the circuit universally adaptable to multiple voltage ranges by designing it to accept extra-low voltage signals (≤120V) and low voltage signals (<1500V) simultaneously. The control unit can selectively activate different Zener diodes based on the input signal type, making the same circuit serve multiple functions across different application scenarios.
2Adaptability or versatility
If multiple Zener diodes with different breakdown voltages are used, then multiple switching thresholds can be implemented, but the circuit complexity increases
Solution Approach 1:
The patent merges multiple Zener diodes with different breakdown voltages into a single parallel circuit configuration, all controlled by one control unit. This combining approach allows multiple switching thresholds to be implemented while sharing common control logic and power supply circuits, thereby limiting the increase in overall system complexity.
Solution Approach 2:
The patent introduces dynamic control through a control unit that can selectively enable or disable specific Zener diodes based on the input signal characteristics. This dynamic switching capability allows the circuit to adapt its complexity level - using only the necessary Zener diodes for each specific application, thus optimizing the balance between functionality and circuit complexity.
3Device complexity
If the switching threshold is fixed, then the circuit design is simple, but it cannot adapt to different voltage ranges
Solution Approach 1:
The patent transforms the fixed switching threshold into a dynamic, adjustable parameter through the control unit. The control unit receives signals and selectively activates different Zener diodes based on whether the input is an extra-low voltage signal or a low voltage signal, enabling the circuit to adapt to different voltage ranges without redesigning the entire circuit.
Solution Approach 2:
The patent changes the switching threshold parameter dynamically by selecting different Zener diodes with different breakdown voltages (3.3V, 6.8V, 10V) based on the input signal type. This parameter change approach allows the same circuit hardware to serve multiple voltage range applications by simply changing which Zener diode is active, rather than requiring different hardware designs.
4Adaptability or versatility
If a rectifier circuit is added to handle AC signals, then the circuit can process both AC and DC signals, but the circuit complexity increases
Solution Approach 1:
The patent makes the circuit universally capable of processing both AC and DC signals by integrating a rectifier circuit that converts AC input signals into DC form. The control unit then processes both original DC signals and rectified DC signals (from AC inputs) through the same Zener diode threshold detection mechanism, achieving multi-functionality without creating entirely separate processing paths.
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
Enables flexible and quick setting of standard switching thresholds across various voltage ranges, ensuring adaptability and safety in different application areas by allowing multiple switching thresholds to be implemented, even in hazardous voltage environments.
Implementation Method 1
an input-side rectifier or rectifier circuit for converting incoming digital ac signals into dc currents
Implementation Method 2
two or a plurality n of series-connected reverse-biased Zener diodes
Implementation Method 3
an optocoupler for determining the state of the digital output terminal
Data Source
AI summary
Disclosed is a large-range input circuit for digital signals in the range of extra-low voltage signals of ≦120 V and in the range of low voltage signals of <1500 V, said input circuit comprising series-connected Zener diodes that are polarized in the reverse direction, each one defining at least one switching threshold in the range of the extra-low voltage signals or in the range of the low voltage signals, and can be selected to be active by not being bridged, wherein a respective auxiliary optocoupler, which can be controlled by a microprocessor, is used to bridge the inactive Zener diode.