Flashlight Switch and Seal Assembly for Waterproof Tactile Feedback

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Solution Overview

Problem

Existing flashlight assemblies have bulky, expensive, and unreliable seals in their electronics compartments, and tail switches lack adequate operational feedback.

Innovation Solution

A flashlight assembly with a plastic membrane seal and a wave spring switch assembly that provides a waterproof barrier and improved tactile feedback, featuring a switch button with a sealing boot and actuator that changes the light source's operation states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If compression-type seals are used to seal the electronics compartment, then the seal provides a waterproof barrier, but the seal becomes bulky and expensive to produce

Engineering Contradiction:
Improvewaterproof seal reliabilityVSAvoidseal bulk and cost
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses a thin film adhesive seal that conformally seals around the battery and electronics components. This flexible thin film approach replaces bulky compression seals, achieving waterproofing while reducing size and cost. The adhesive seal conforms to the contours of internal components without requiring thick compression structures.

Inventive Principle:
Principle #30Flexible shells and thin films

2Ease of operation

If existing tail switch designs are used, then the switch is located on the tail side, but adequate operational feedback is not provided to the user

Engineering Contradiction:
Improveswitch operationVSAvoidoperational feedback to user
Core Design Contradiction:
Ease of operationVSLoss of information

Solution Approach 1:

The patent incorporates a tactile feedback mechanism in the tail switch assembly where the actuator provides mechanical resistance and tactile response when depressed. This feedback loop allows the user to sense the switch state change through touch, confirming operational status without visual feedback, thereby addressing the information loss problem.

Inventive Principle:
Principle #23Feedback

3Reliability

If a sealed electronics compartment is used, then the electronics are protected, but the seal becomes unreliable and expensive

Engineering Contradiction:
Improveelectronics compartment sealingVSAvoidseal production cost and complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts the sealing function from a separate bulky seal component and integrates it directly onto the battery and electronics housing using adhesive. This integration eliminates the need for separate compression seal rings or gaskets, simplifying manufacturing while maintaining reliable sealing protection for the electronics compartment.

Inventive Principle:
Principle #2Taking out (Extraction)

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 offers a compact, cost-effective, and durable design with enhanced operational feedback, ensuring a reliable waterproof seal and improved user experience.

Implementation Method 1

a wave spring, the wave spring being compressed between the switch button and the sealing boot

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 2

the perimeter of the seal is removably attachable and reattachable to the sealing surface of the subframe using an adhesive material

Methodology Applied
Scientific EffectAdhesive: Adhesive

Data Source

PatentEP4685398A1Flashlight assembly
Publication Date: 2026.01.28 STREAMLIGHT INC
  • EP4685398A1 patent drawingFigure 1
  • EP4685398A1 patent drawingFigure 2
  • EP4685398A1 patent drawingFigure 3

AI summary

A lighting device having a body includes a light assembly, an electronics subassembly, and a switch assembly. The light assembly is secured to the electronics subassembly at a front end of the body and the switch assembly is secured to the electronics subassembly at a rear end of the body. The electronics sub assembly houses, within a sealed internal volume, a battery and a circuit board. The switch assembly includes a switch button, a sealing boot and a wave spring.