Projectile Position Detection Using Orthogonal Light Curtains

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Solution Overview

Problem

Existing systems for detecting the position of projectiles or arrows in shooting ranges face challenges such as increased technical complexity, large design size, and reduced light signal strength due to additional screens or lenses, leading to parallax errors and reduced evaluation accuracy.

Innovation Solution

A compact device using two orthogonally arranged light curtains with telecentric lenses and a deflection system that allows the camera to be positioned on the same side as the light source, enabling precise position detection and speed inference through multiple image capture, while maintaining a compact design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a ground glass screen and optical system are used to form shadow projection, then the position detection function is achieved, but the light signal is weakened and technical complexity increases

Engineering Contradiction:
Improveposition detection accuracyVSAvoidtechnical complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent removes the ground glass screen from the optical path, extracting the problematic element that weakened the light signal. Instead, it uses a direct shadow projection method where the projectile's shadow falls directly onto the sensor array, eliminating the screen while maintaining position detection capability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a light-tight enclosure with precisely positioned apertures as an intermediary structure. This enclosure with controlled openings serves as the new optical element, replacing the ground glass screen and enabling direct shadow capture on the sensor without signal loss.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If a ground glass screen and optical system are used to form shadow projection, then the position detection function is achieved, but the apparatus size increases

Engineering Contradiction:
Improveposition detection accuracyVSAvoidapparatus size
Core Design Contradiction:
Measurement precisionVSVolume of stationary object

Solution Approach 1:

The patent removes the ground glass screen and complex optical system, extracting the elements that required large distances between components. This reduction in optical components directly enables a more compact apparatus design while maintaining detection accuracy.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent transitions from a traditional optical projection system requiring longitudinal space to a planar aperture-sensor configuration. By changing the dimensional arrangement of optical elements, the apparatus achieves compactness while preserving the shadow projection detection function.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Area of stationary object

If a punctiform light source is widened by a lens, then illumination coverage is improved, but the distance between light source and evaluating surface must be increased

Engineering Contradiction:
Improveillumination coverage areaVSAvoiddistance between light source and evaluating surface
Core Design Contradiction:
Area of stationary objectVSLength of stationary object

Solution Approach 1:

The patent removes the lens from the light path, extracting the element that required increased distance for focal point formation. Instead, it uses a planar light source with apertures that provides wide illumination coverage without requiring focal distance, enabling compact design.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the lens-based optical focusing system with a geometric aperture system. This substitution eliminates the need for focal distance while maintaining illumination coverage, as the apertures directly define the illumination geometry without requiring optical focusing.

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

This solution achieves high evaluation accuracy and compact design by eliminating parallax errors and reducing the size of the apparatus, allowing for precise position detection and speed verification of fast-moving projectiles, thereby filtering out false signals.

Implementation Method 1

at least one light source which emits a strip of light and emits light into an evaluation plane

Methodology Applied
Scientific EffectLight propagation: Light

Implementation Method 2

at least one lens through which the light emitted by the light source is guided

Methodology Applied
Scientific EffectRefraction and focusing: Lens

Implementation Method 3

at least one camera device into which the light is guided after the lens

Methodology Applied
Scientific EffectPhotoelectric detection: Photoelectric Effect

Data Source

PatentEP1892495B1Device and method for electronic evaluation of hits
Publication Date: 2011.12.14 KNESTEL ELEKTRONIK
  • EP1892495B1 patent drawingFigure 1
  • EP1892495B1 patent drawingFigure 2
  • EP1892495B1 patent drawingFigure 3

AI summary

The device has a light source (1) sending light in an evaluation plane, where a lens (3) is used to guide the light sent by the light source. A camera device (4) is provided, into which the focused light from the lens is guided. An evaluation device evaluates a signal of the camera device and outputs a position of the object e.g. projectile. A deflection device (8) is arranged behind the lens and deflects an optical path of the light directly behind the lens twice around an angle of 90 degree. An independent claim is also included for a method for the collection of the position of a moving article.