Free-Form Windshield for Optoelectronic Sensor Reflection Management

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Solution Overview

Problem

Conventional laser scanners face challenges in effectively suppressing windshield reflections due to the coaxial arrangement of transmission and reception beam paths, which can lead to interference and require extensive installation space or scattered light entry into the reception path.

Innovation Solution

The design features a free-form surface for the windshield, with a curved course perpendicular to the monitoring plane and a non-coaxial arrangement of the light transmitter and receiver, utilizing a convex curvature to deflect reflections into an optical trap, ensuring minimal interference and compact design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a conventional coaxial arrangement of transmission and reception beam paths is used, then the optical system is compact and simple, but windshield reflections interfere with the reception path and require extensive installation space for optical traps

Engineering Contradiction:
Improveoptical system arrangementVSAvoidwindshield reflection interference
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent applies asymmetry by using a non-coaxial arrangement where the transmission beam path and reception beam path are spatially separated and offset from each other. This asymmetric configuration prevents the windshield reflection from entering the reception path while maintaining a compact design without requiring large optical traps

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent resolves the contradiction by moving the reception beam path to another spatial dimension (lateral offset) rather than relying on vertical optical traps. This dimensional change allows the system to avoid windshield reflections without increasing the overall footprint or complexity of the optical system

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

2Adaptability or versatility

If the transmission beam strikes the windshield at different heights, then the system is more adaptable to varying conditions, but a conventional frustoconical windshield cannot deflect reflections properly and scattered light enters the reception path

Engineering Contradiction:
Improvebeam height variationVSAvoidscattered light interference
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by providing different surface characteristics at different locations on the windshield. The first region (transmission side) has a first curvature optimized for beam transmission, while the second region (reception side) has a second curvature optimized for deflecting reflections away from the reception path. This localized differentiation allows the windshield to handle beams at various heights while preventing scattered light interference

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent uses curved surfaces (spheroidality) on both sides of the windshield to properly deflect light beams. The first curvature on the transmission side and the second curvature on the reception side work together to redirect reflections away from the reception path regardless of the beam's height, preventing scattered light from entering the detection system

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 effectively diverts windshield reflections independently of beam height and lateral displacement, maintaining beam path integrity and enabling reliable object detection with reduced installation space and interference.

Implementation Method 1

the transmitted beam is reflected, which can have a disruptive effect on the measurement

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP2447733B1Optoelectronic sensor
Publication Date: 2013.03.13 SICK AG
  • EP2447733B1 patent drawingFigure 1~2
  • EP2447733B1 patent drawingFigure 3~4
  • EP2447733B1 patent drawingFigure 5~6

AI summary

The sensor (10) has a front disk (42) designed as a free form surface including a curved contour in a section perpendicular to a monitoring plane (22) and through a central axis (30). Each secant of the contour is tilted relative to an axis so that the contour is inwardly or outwardly bent. The disk has a shape of a hollow mirror so that reflections (44) of a transmitted light radiation (16) at the disk are deflected in a common focal point independent of a height position relative to the plane. The focal point is arranged above or below the disk. An independent claim is also included for a method for detecting objects in a monitoring plane.