DC Voltage Testing Circuit with Self-Powered LCD Indication
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Solution Overview
Problem
Existing DC voltage detection systems for high voltages require a separate power supply and are complex, with high currents affecting upstream voltage dividers due to LED discharge.
Innovation Solution
A DC voltage testing system using a liquid crystal display segment, incorporating a voltage divider, threshold switch with hysteresis, and an astable multivibrator oscillator, which draws energy from the measurement signal, eliminating the need for a separate power supply and minimizing current draw.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If LED display is used with charging capacitor discharge, then voltage indication is achieved, but high current flows through the LED causing undesirable effects on the upstream voltage divider
Solution Approach 1:
The patent replaces the LED display mechanism with a liquid crystal display (LCD) segment that does not require high discharge currents. The LCD is controlled by a threshold switch and oscillator circuit that generates appropriate drive signals from the divided voltage, eliminating the harmful high current effect while maintaining visible voltage indication.
2Power
If separate power supply is used for DC voltage testing system, then sufficient power is available for display operation, but system complexity and component count increase
Solution Approach 1:
The patent implements self-service by having the measurement signal itself provide the power for the display operation. The oscillator circuit is powered by the divided voltage from the measurement signal, and the threshold switch uses the same voltage source. This eliminates the need for a separate power supply while ensuring sufficient power availability for display operation.
Solution Approach 2:
The patent applies multi-functionality by making the measurement signal serve dual purposes: both indicating the voltage level through the LCD display and providing power to the oscillator and threshold switch circuits. This universal use of the measurement signal reduces system complexity while maintaining functional requirements.
3Adaptability or versatility
If high voltage DC testing is performed, then real-world application is achieved, but risk of overvoltage damage to display and measurement circuits increases
Solution Approach 1:
The patent introduces an intermediary voltage divider circuit that safely reduces the high measurement voltage to a level appropriate for the LCD display and control circuits. The voltage divider, consisting of resistors R1 and R2, acts as a mediator between the high voltage measurement signal and the low-voltage display system, protecting against overvoltage damage while enabling high voltage application capability.
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 system effectively displays DC voltage levels above 100 volts without a separate power supply, protecting the display from overvoltage and reducing current consumption.
Implementation Method 1
a liquid crystal display segment (10) connected thereto
Implementation Method 2
an oscillator (9), wherein the oscillator (9) generates alternating voltage signals
Data Source
Figure 1~2A
Figure 2b~5
Figure 3~4
AI summary
A DC voltage test system for indicating a voltage, the DC voltage test system comprising a threshold switch, an oscillator connected thereto, and a liquid crystal display segment connected to the oscillator for indicating a state of the DC voltage, ie whether the DC voltage is above or below a threshold.