Optical Piston Position Detection for Airsoft Gearbox

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Solution Overview

Problem

Existing airsoft gun replicas lack control over the piston position, leading to inconsistent operation and reduced mechanical part lifespan due to uncontrolled piston movement upon trigger release.

Innovation Solution

A sensor system using two printed circuit boards with light sources and detectors, connected to a microcontroller, precisely determines the piston position by analyzing light signals, allowing controlled piston movement and improved gear mechanism reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If no piston position control system is used, then the device complexity is reduced, but the reliability of the gear mechanism deteriorates due to uncontrolled piston movement

Engineering Contradiction:
Improvegearbox reliabilityVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical position control mechanisms with an optical sensing system. A light source and light detector are used to detect the position of piston gear teeth, and a microcontroller processes this information to control motor shutdown. This substitution of mechanical control with optical-electronic control achieves precise piston positioning while maintaining relatively simple device architecture.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a feedback control system where the light detector continuously monitors the position of piston gear teeth and provides this information to the microcontroller. Based on this feedback, the microcontroller determines the optimal shutdown moment for the motor, ensuring the piston stops at the desired position. This closed-loop feedback mechanism reliably controls piston position without requiring complex mechanical control structures.

Inventive Principle:
Principle #23Feedback

2Duration of action of moving object

If piston position is uncontrolled, then the ease of operation is maintained, but the duration of action of mechanical parts deteriorates due to increased wear

Engineering Contradiction:
Improvemechanical parts lifespanVSAvoidoperation simplicity
Core Design Contradiction:
Duration of action of moving objectVSEase of operation

Solution Approach 1:

The patent employs a self-service approach where the system automatically detects piston position using the optical sensor and microcontroller, and autonomously determines the optimal shutdown moment. The motor is controlled to stop when the light detector detects specific piston gear tooth positions, ensuring the piston returns to the starting position without user intervention. This automatic self-control extends mechanical parts lifespan while requiring no additional operational complexity from the user.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If piston position detection system is added, then the measurement precision of piston position is improved, but the device complexity increases

Engineering Contradiction:
Improvepiston position detection accuracyVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent achieves precise piston position measurement by substituting mechanical position sensing with an optical detection system. A light source emits light toward the piston gear, and a light detector measures the light intensity variations caused by passing gear teeth. This optical measurement method provides high position detection precision without requiring complex mechanical encoders or sensors, thereby achieving accurate measurement with relatively simple device architecture.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

Enables consistent piston movement cycles and extended gearbox life by accurately controlling piston position, reducing wear and improving operational reliability.

Implementation Method 1

A sensor system using two printed circuit boards with light sources and detectors, connected to a microcontroller, precisely determines the piston position by analyzing light signals

Methodology Applied
Scientific EffectLight detection: Photoelectric Effect

Data Source

PatentEP4400800B1Gun replica with piston position detection system
Publication Date: 2026.03.18 GATE ENTERPRISE SP ZOO SPOLKA KOMANDYTOWA
  • EP4400800B1 patent drawingFigure 1
  • EP4400800B1 patent drawingFigure 2~3
  • EP4400800B1 patent drawingFigure 4~5

AI summary

At least two light sources D (10 and 11) are located on at least one printed circuit board (9) and at least two light detectors Q (12 and 13) are located on at least one printed circuit board (9"), with the boards (9 and 9") located on opposite inner walls of the replica's skeleton in such a way, that the active surface of each light source D faces the reciprocating gear (1) and the active surface of one light detector Q, and the geometric centers of the light sources D and the corresponding light detectors Q, are located on lines I parallel to each other that intersect the two printed circuit boards (9, 9") perpendicularly. The distance between adjacent light sources D (10 and 11) and the distance between adjacent light detectors Q (12 and 13) is equal to half of the distance between the vertical axes A of the teeth of the outer mesh of the reciprocating gear (1) or an odd multiple thereof, so that while one tooth constitutes an aperture for the light emitted by light source D, a light signal flows through the free space between that tooth and an adjacent tooth from the light source D to the corresponding light detector Q, with the light sources D (10 and 11) connected to a microcontroller pin and the light detectors Q (12 and 13) connected to microcontroller pins equipped with an analog-to-digital converter U or to external analog-to-digital converters U.