Voltage Supply Circuit for Electroluminescent Foils

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Solution Overview

Problem

Existing systems fail to quickly and safely disconnect power from loads with significant capacitive components, such as electroluminescent films, when external influences like human contact cause leakage currents, potentially leading to dangerous situations.

Innovation Solution

A method and circuit utilizing a controlled AC voltage source with a microprocessor-controlled switch to interrupt the power supply briefly and measure voltage drops, allowing for rapid detection of harmful leakage resistances and immediate disconnection if thresholds are exceeded, ensuring safety without significant power interruptions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If continuous power supply is maintained to electroluminescent films, then operational continuity is improved, but safety response to leakage currents is worsened due to delayed detection

Engineering Contradiction:
Improvesafety responseVSAvoidpower supply interruption
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent implements periodic measurement cycles where the power supply is temporarily interrupted at regular intervals to measure leakage current. This periodic action allows the system to maintain continuous operational monitoring while enabling safety checks, resolving the contradiction between operational continuity and safety response capability.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system performs preliminary measurements of leakage current during brief power interruptions before actual hazards can develop. By detecting leakage currents early during these scheduled measurement periods, the system can prepare safety responses in advance, improving reliability without causing significant operational disruption.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If power supply is interrupted frequently to check for leakage currents, then safety detection is improved, but operational continuity is worsened

Engineering Contradiction:
Improveleakage current detectionVSAvoidoperational continuity
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies partial action by interrupting power supply only for brief measurement intervals rather than continuous monitoring. These short interruptions are sufficient to obtain accurate leakage current measurements while minimizing impact on operational continuity, effectively balancing safety detection with productivity.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The measurement circuit serves multiple functions: it detects leakage currents, characterizes load behavior, and provides safety monitoring. This multi-functionality allows the system to achieve comprehensive safety detection during brief measurement periods, reducing the frequency and duration of power interruptions needed.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Measurement precision

If measurement is based on auxiliary voltage source rather than supply voltage, then measurement accuracy is improved, but system complexity is worsened

Engineering Contradiction:
Improveleakage current measurementVSAvoidvoltage source requirement
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an auxiliary voltage source as an intermediary element that enables accurate leakage current measurement independent of the main power supply voltage. This intermediary voltage source allows measurements to be performed under controlled conditions, improving measurement precision while the measurement circuit integrates it into the existing system architecture.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 rapid detection and prevention of hazardous leakage currents, ensuring safe operation of electroluminescent films by quickly identifying and responding to changes in leakage resistance, thereby preventing damage and ensuring user safety.

Implementation Method 1

a capacitive load (B, C), in particular an electroluminescent light foil, whose equivalent circuit diagram represents the series connection of a resistor and a capacitor

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP1970717B1Circuit and method for supplying voltage to electroluminescent foils
Publication Date: 2017.08.02 LUNATONE INDUSTRIELLE ELEKTRONIK GMBH
  • EP1970717B1 patent drawingFigure 1~2b
  • EP1970717B1 patent drawingFigure 3

AI summary

The method involves separating a supply terminal for a short time interval from the load and at the load terminal the voltage curve is observed. A difference of the voltage at the beginning of the time duration and the voltage at the end of the time duration and an error signal is delivered with exceeding of the difference over a reference value. An independent claim is also included for a circuit for voltage supply by electroluminescent foils.