LED Driver IC Short-Circuit Detection for Luminance Hold

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Solution Overview

Problem

Existing light emitting element driving devices face insufficient luminance issues due to a decrease in the number of functioning light emitting diodes, which can compromise safety, and existing solutions either increase component count and power consumption or are not applicable to series-connected diodes.

Innovation Solution

A light emitting element driving semiconductor integrated circuit with a single-element short-circuit detection unit and a control unit that increases current to series-connected diodes when a short-circuit is detected, and a determining unit that adjusts power supply to maintain luminance by stopping or increasing current as needed based on diode availability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If backup light emitting diodes and driving circuits are added to maintain luminance when diodes fail, then luminance sufficiency is improved, but device complexity and power consumption increase

Engineering Contradiction:
ImproveluminanceVSAvoidcomponent count
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The invention changes the electrical parameters (current magnitude and pulse width) of the driving signal dynamically based on the number of functioning light emitting diodes. When diodes fail, the driving circuit increases the current and adjusts the pulse width to compensate for the reduced number of diodes, thereby maintaining sufficient luminance without requiring additional backup components

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The driving circuit dynamically adjusts its operating parameters in response to detected diode failures. The control unit modifies the driving signal characteristics (current level, pulse duration) in real-time based on feedback about the number of functioning diodes, enabling adaptive luminance maintenance without static backup structures

Inventive Principle:
Principle #15Dynamics

2Illumination intensity

If backup light emitting diodes and driving circuits are added to maintain luminance when diodes fail, then luminance sufficiency is improved, but power consumption increases

Engineering Contradiction:
ImproveluminanceVSAvoidpower consumption
Core Design Contradiction:
Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The invention changes the electrical parameters (current magnitude and pulse width) of the driving signal dynamically based on the number of functioning light emitting diodes. When diodes fail, the driving circuit increases the current and adjusts the pulse width to compensate for the reduced number of diodes, thereby maintaining sufficient luminance without requiring additional backup components

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The driving circuit maintains continuous useful action by dynamically adjusting the driving signal to ensure that the total luminous output remains sufficient even as individual diodes fail. By continuously adapting the current and pulse width, the system maintains effective illumination without needing redundant backup components that would consume additional power

Inventive Principle:
Principle #20Continuity of useful action

3Reliability

If existing control techniques are applied to series-connected diodes, then short-circuit protection is improved, but luminance sufficiency deteriorates due to current reduction

Engineering Contradiction:
Improveshort-circuit protectionVSAvoidluminance
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

The driving circuit dynamically adjusts its operating parameters in response to detected diode failures. The control unit modifies the driving signal characteristics (current level, pulse duration) in real-time based on feedback about the number of functioning diodes, enabling adaptive luminance maintenance without static backup structures

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention converts the harmful effect of diode failure (reduced luminance) into a manageable parameter change. By detecting the number of functioning diodes and adjusting the driving signal accordingly, the system transforms the potential harm of component failure into a controlled parameter adjustment that maintains overall system performance

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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

Prevents insufficient luminance by ensuring continued adequate light output even when one or more diodes fail, while minimizing component count and power consumption, and alerts users to potential issues through notification signals.

Implementation Method 1

a plurality of light emitting diodes Z1 to Z3

Methodology Applied
Scientific EffectLight emitting diode effect: Light Emitting Diode

Data Source

PatentEP3247173B1Integrated circuit for driving a light emitting element
Publication Date: 2021.10.13 ROHM CO LTD
  • EP3247173B1 patent drawingFigure 1
  • EP3247173B1 patent drawingFigure 2
  • EP3247173B1 patent drawingFigure 3

AI summary

A light emitting element driving semiconductor integrated circuit constitutes at least a part of a light emitting element driving device arranged to drive a series connection unit including a plurality of light emitting elements. The light emitting element driving semiconductor integrated circuit includes a single-element short-circuit detection unit arranged to detect that one of the plurality of light emitting elements is short-circuited, and a control unit arranged to control a power element of the light emitting element driving device so that current supplied from the light emitting element driving device to the series connection unit is increased, when the single-element short-circuit detection circuit detects that one of the plurality of light emitting elements is short-circuited.