Vehicle Light Module Surge Protection With Parallel Varistor

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Solution Overview

Problem

Existing light emitting modules face challenges in protecting light emitting elements from negative surges, suppressing voltage drops, and achieving miniaturization, particularly when using field effect transistors for protection.

Innovation Solution

A light emitting module design incorporating a field effect transistor connected between the anode and cathode sides of the light emitting element, with a varistor in parallel to the field effect transistor, to manage voltage drops and protect against surges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a diode is connected in series with multiple light emitting elements to protect against negative surge, then the light emitting element is protected, but the voltage drop becomes large

Engineering Contradiction:

Improveprotection against negative surgeVSAvoidvoltage drop

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent introduces a field effect transistor as an intermediary component between the light emitting elements and the power supply. The FET acts as a voltage-controlled switch that can block negative surges while maintaining low forward voltage drop, thus protecting the light emitting elements without significant energy loss.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the operational parameters of the field effect transistor by controlling its gate voltage. By adjusting the gate voltage, the FET can transition between off-state (blocking negative surge) and on-state (allowing forward current with minimal voltage drop), thus dynamically optimizing both protection and energy efficiency.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If a field effect transistor is used to protect the light emitting element against negative surge, then the voltage drop is reduced, but the device becomes large in size

Engineering Contradiction:

Improvevoltage dropVSAvoidsize of field effect transistor

Core Design Contradiction:

Loss of energyVSVolume of moving object

Solution Approach 1:

The patent combines the field effect transistor with the light emitting elements into an integrated module structure. By merging these components and sharing common substrates, packaging, and electrical connections, the overall size increase is minimized while maintaining the voltage drop reduction benefits of the FET.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent employs a nested arrangement where the field effect transistor is integrated within the same package or substrate as the light emitting elements. The FET is positioned and connected in a space-efficient manner, nesting the protection function within the existing module footprint rather than adding external components.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Illumination intensity

If multiple light emitting elements are connected in series to achieve high luminous flux, then the luminous flux increases, but the voltage drop increases

Engineering Contradiction:

Improveluminous fluxVSAvoidvoltage drop

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The field effect transistor serves as an intermediary that decouples the relationship between series-connected light emitting elements and the power supply voltage. By controlling the FET's on-resistance through gate voltage, the system can maintain high luminous flux from multiple series elements while minimizing the additional voltage drop through efficient current control.

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

The design effectively protects the light emitting elements from negative surges while minimizing voltage drops and enabling miniaturization of the module.

Implementation Method 1

a varistor limiting a voltage to be applied to the field effect transistor

Methodology Applied

Scientific EffectVaristor voltage clamping: Electrical Resistance

Implementation Method 2

a field effect transistor electrically connected between an anode side and a cathode side of the light emitting element and a DC power supply

Methodology Applied

Scientific EffectField effect transistor switching: Electrical Resistance

Data Source

PatentUS20260063261A1Light emitting module, vehicle lighting device, and vehicle lamp

Publication Date: 2026.03.05 TOSHIBA LIGHTING & TECHNOLOGY CORP

AI summary

A light emitting module, a vehicle lighting device, and a vehicle lamp are capable of achieving protection of a light emitting element against a negative surge, suppression of a voltage drop, and miniaturization. The light emitting module includes: at least one light emitting element; a field effect transistor electrically connected between an anode side and a cathode side of the light emitting element and a DC power supply; and a varistor connected in parallel with the field effect transistor.