Embedded Radial Fired Laser Igniter for Munitions

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Solution Overview

Problem

Current ignition systems for small, medium, and large caliber munitions face reliability and safety issues due to bridge wires, which are prone to breakage and susceptible to RF and ESD, and laser-based ignition technologies require specialized construction and equipment, making them costly for high production quantities and unsuitable for small devices.

Innovation Solution

A laser ignition assembly using a vertical solder bridge between two standard copper clad circuit boards to connect an edge emitting laser diode, allowing for automated assembly with existing surface mount equipment and embedding the ignition material within the primer cup, thus maintaining the energetic train's space efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional bridge wire ignition systems are used, then the device can be manufactured with simple materials, but the reliability is poor due to wire breakage and susceptibility to RF and ESD

Engineering Contradiction:

Improveignition system reliabilityVSAvoidsusceptibility to RF and ESD

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the traditional mechanical/electrical bridge wire ignition system with an optical laser-based ignition system. The laser diode emits light energy that directly ignites the propellant, eliminating the need for physical bridge wires that are susceptible to RF interference and electrostatic discharge. This substitution of mechanical/electrical components with optical components resolves the reliability and environmental susceptibility issues.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If laser based ignition technology is used, then safety is improved by removing energetic material from the primer cavity, but manufacturing cost increases due to specialized construction techniques and equipment

Engineering Contradiction:

Improvesafety hazardsVSAvoidmanufacturing cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent designs the laser ignition assembly to be compatible with existing primer cup structures and ammunition manufacturing infrastructure. The laser diode, mounting structure, and electrical connections are configured to fit within standard primer dimensions, allowing integration into existing production lines without requiring specialized construction equipment or techniques. This universality approach maintains safety benefits while avoiding increased manufacturing costs.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent replicates the familiar primer cup structure and overall ignition system architecture, maintaining compatibility with existing manufacturing processes and quality control procedures. By copying the established form factor and integration method, the laser-based system can be produced using conventional ammunition manufacturing infrastructure, avoiding the need for expensive specialized equipment.

Inventive Principle:

Principle #26Copying

3Reliability

If laser ignition assembly is added to primer cup, then ignition reliability is improved, but the space for the energetic train increases

Engineering Contradiction:

Improveignition reliabilityVSAvoidspace for energetic train

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent nests the laser diode, mounting structure, and electrical connections within the existing primer cup cavity. The laser ignition assembly is designed to fit inside the primer cup's internal volume, utilizing the same space that traditionally contained only the bridge wire and explosive filler. This nesting approach adds the laser ignition functionality without increasing the overall primer or energetic train volume.

Inventive Principle:

Principle #7Nested doll (Nesting)

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 solution provides a reliable, safe, and cost-effective ignition system suitable for high production volumes, eliminating the need for specialized equipment and reducing the risk of environmental hazards, while maintaining the compactness required for small energetic devices.

Implementation Method 1

an edge emitting laser diode disposed between the first mounting surface and the second mounting surface and oriented such that a light fluence from the edge emitting laser diode is directed in a radial direction into the central cavity

Methodology Applied

Scientific EffectLight Emitting Diode: Light Emitting Diode

Implementation Method 2

a vertical solder bridge formed between the first mounting surface and the second mounting surface

Methodology Applied

Scientific EffectElectrical Conduction: Conduction (electrical)

Data Source

PatentUS11536551B1Embedded radial fired laser igniter

Publication Date: 2022.12.27 UNITED STATES OF AMERICA THE AS REPRESENTED BY THE SEC OF THE ARMY

AI summary

A laser ignition assembly comprises first and second mounting surfaces opposed to each other. A central cavity is formed through the surfaces and sized to receive energetic material therein. A vertical solder bridge is formed between the surfaces and an edge emitting laser diode disposed between the surfaces. The laser diode is oriented such that a light fluence therefrom is directed in a radial direction into the central cavity. The surfaces can be circuit boards, e.g., copper clad, rigid circuit boards, and have an annular shape. The central cavity can be further defined by an interboard gap between the surfaces. The ignition assembly can fit within a primer cup of a munition.