ADF Driver Circuitry Time Delay for Current Spike Reduction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Automatic darkening filter (ADF) eye protection devices experience high peak currents and battery drain due to near instantaneous switching of voltage polarity, causing stress on electronic components.

Innovation Solution

The implementation of time delay circuits in the driver circuitry for ADF devices, which delay the application of control voltages to the liquid crystal device, preventing simultaneous conduction of drivers and thus avoiding high current spikes, using resistor-capacitor timing circuits to control the switching of voltage polarity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If voltage polarity is switched very close to instantaneously across the LCD filter, then the ADF response time is improved, but high peak currents are generated that stress electronic components and produce high battery drain

Engineering Contradiction:

ImproveADF response timeVSAvoidbattery drain

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The patent applies preliminary action by implementing time delay circuits that prepare the driver circuits for sequential switching. The delay circuits pre-establish the timing sequence before the actual voltage polarity switching occurs, ensuring that one driver is fully off before the other turns on, thereby preventing simultaneous conduction and the associated high peak currents while maintaining fast ADF response

Inventive Principle:

Principle #10Preliminary action

2Speed

If voltage polarity is switched very close to instantaneously across the LCD filter, then the ADF response time is improved, but electronic components experience high stress

Engineering Contradiction:

ImproveADF response timeVSAvoidcomponent stress

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The time delay circuits pre-establish the switching sequence before voltage polarity changes occur, ensuring that driver circuits are never simultaneously on. This preliminary timing arrangement prevents high peak currents and reduces stress on electronic components while maintaining fast ADF response time

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements beforehand cushioning by using RC time delay circuits that act as protective elements between the driver circuits. These delay circuits cushion the switching transitions, preventing direct high-stress instantaneous switching while maintaining the required fast response performance of the ADF device

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If time delay circuits are added to prevent simultaneous driver conduction, then component stress and battery drain are reduced, but device complexity increases

Engineering Contradiction:

Improvecomponent stressVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by modifying the timing parameters of the driver circuit switching. Instead of changing the fundamental circuit architecture, the invention adjusts the time delay parameter through RC circuits to achieve sequential switching. This maintains circuit simplicity while effectively preventing simultaneous driver conduction and reducing component stress

Inventive Principle:

Principle #35Parameter changes

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 reduces electrical component stress and battery drain by ensuring that there is no overlap in the conduction states of the drivers, resulting in a more efficient and reliable operation of ADF systems.

Implementation Method 1

using resistor-capacitor timing circuits to control the switching of voltage polarity

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

First through fourth time delay circuits are associated with each of the first through fourth driver circuits. The timer circuits, under control of a switch control circuit, operate to delay application of control voltages to the LCD filter control terminals

Methodology Applied

Scientific EffectTime delay:

Implementation Method 3

ADF systems often include a liquid crystal device (LCD) that is generally driven with shade voltages applied across the filter

Methodology Applied

Scientific EffectLiquid crystal effect: Liquid Crystals

Implementation Method 4

liquid crystal device (LCD) filter having first and second control terminals to which are coupled first through fourth driver circuits

Methodology Applied

Scientific EffectElectro-optic effect: Electro-Optic Effects

Data Source

PatentEP2621429B1Automatic darkening filter (ADF) eye protection device with improved drive circuitry

Publication Date: 2014.10.08 KIMBERLY CLARK WORLDWIDE INC

Figure 1~2
Figure 3

AI summary

Disclosed is an apparatus and methodology for operating an automatic darkening filter (ADF) eye protection device. An operating voltage is alternately applied to a pair of control terminals of an ADF device circuit in a continuing sequence where a first polarity voltage is applied to the pair of terminals and then reversed. A delay period is provided between application of the alternating polarities. In some embodiments ground potential is applied to both terminals of the pair of terminals during the delay period.