Optical Position Encoder LED Window Coating for Higher Resolution
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Solution Overview
Problem
Optical position encoders using LED light sources face issues with light emission impairments due to glass plates, leading to refractions, reflections, and reduced resolution, which affect signal quality and measurement accuracy.
Innovation Solution
The light exit surface of the LED light source is coated and selectively stripped to create a precise light exit window, allowing for improved radiation properties and higher resolutions, independent of manufacturing tolerances, by using coatings such as metallic coatings like gold or chrome-gold alloys and precise stripping techniques like etching or lasering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glass plate is arranged above the LED light source to protect it and enable defined radiation, then the LED light source is protected from damage, but unwanted refraction and reflection of light rays occur, leading to falsified measurement results
Solution Approach 1:
The harmful glass plate is completely removed from the system. The patent exposes the light exit surface of the LED light source to the outside environment, eliminating the intermediate glass plate that caused refraction and reflection issues. This extraction of the harmful element resolves the contradiction by removing the source of measurement errors while maintaining LED protection through alternative means.
Solution Approach 2:
The molded housing serves as a new intermediary structure that protects the LED light source without interfering with light emission. Instead of using a glass plate that optically interfered with the light path, the patent employs a molded housing that provides mechanical protection while allowing the light exit surface to remain exposed, thus eliminating refraction and reflection problems.
2Ease of manufacture
If the light exit surface dimensions are determined by manufacturing tolerances during production, then the LED light source can be easily manufactured, but the resolution of the optoelectronic component is limited by these tolerances
Solution Approach 1:
The light exit surface is pre-coated with a reflective or absorptive material before final assembly, and then a light exit window is created by removing the coating in specific areas. This preliminary coating action allows for precise definition of the light exit window dimensions that are not constrained by LED manufacturing tolerances, thereby improving resolution while maintaining ease of manufacture through a standardized coating process.
Solution Approach 2:
The patent changes the parameter controlling light exit surface dimensions from LED manufacturing tolerances to coating removal dimensions. By applying a coating and then selectively removing it to create a light exit window, the critical dimension is now controlled by the coating process and removal technique rather than by the LED chip fabrication tolerances, enabling higher resolution.
3Measurement precision
If the light exit surface is exposed to the outside to prevent refraction and reflections, then signal quality improves, but the LED light source becomes more vulnerable to damage during the molding process
Solution Approach 1:
The LED light source is pre-coated with a protective and reflective coating before the molding process. This preliminary coating provides both mechanical protection during molding and optical functionality by preventing refraction and reflections, thus resolving the contradiction between protection and signal quality.
Solution Approach 2:
The patent employs a composite structure where the LED light source is combined with a reflective or absorptive coating material. This composite approach provides both the mechanical robustness needed during molding and the optical properties required to prevent refraction and reflections, achieving both protection and signal quality simultaneously.
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 approach enhances the emission properties of the LED light source, resulting in better signal quality and higher resolutions, while being applicable across different LED sources from various manufacturers and batches, with consistent emission properties achieved through controlled coating and stripping processes.
Implementation Method 1
the light exit surface is coated and has a de-coated light exit window... using coatings such as metallic coatings like gold or chrome-gold alloys
Implementation Method 2
using coatings such as metallic coatings like gold or chrome-gold alloys
Implementation Method 3
precise stripping techniques like etching or lasering
Implementation Method 4
precise stripping techniques like etching or lasering
Data Source
Figure 1a~2b
Figure 3~5
Figure 6a~6c
AI summary
The invention relates to a method for producing an optical position encoder (100) comprising an optoelectronic component (1) and a measuring scale (101) which is illuminated by an LED light source (2) of the optoelectronic component (1), wherein the LED light source (2) is molded into a mold housing (11) such that a light outlet surface (5) of the LED light source (2) is outwardly exposed, and the light outlet surface (5) has a coating and is uncoated in some regions in order to provide a light outlet window (10). The invention additionally relates to an optical position encoder (100) comprising an optoelectronic component (1) with a mold housing (11) in which an LED light source (2) is arranged such that a light outlet surface (5) of the LED light source (2) is outwardly exposed, said light outlet surface (5) being coated and having an uncoated light outlet window (10), and comprising a measuring scale (101) which is illuminated by the LED light source (2) of the optoelectronic component (1).