Optical Encoder Protrusion Refracts Stray Light
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Solution Overview
Problem
Optical encoders suffer from reduced resolution due to stray light interference, which introduces false signals and lowers the effectiveness of motion detection.
Innovation Solution
Incorporating a protrusion between the first and second lenses in the optical encoder, made from the same encapsulant material, to refract stray light away from the detector, ensuring that only reflected light reaches the detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If space between lenses is filled with encapsulant material having a flat surface, then the encoder structure is simple and easy to manufacture, but stray light reflects off the flat surface and reaches the detector, reducing measurement precision
Solution Approach 1:
The patent applies curvature by replacing the flat surface between lenses with a domed or curved surface. This curved surface refracts stray light at different angles, preventing it from reaching the detector while maintaining structural simplicity and ease of manufacturing using the same encapsulant material.
Solution Approach 2:
The domed surface acts as an intermediary element between the two lenses. It mediates the path of stray light by refracting it in a controlled manner, redirecting the light away from the detector without requiring additional complex components or materials.
2Measurement precision
If a protrusion is added between lenses to refract stray light, then measurement precision and contrast are improved, but device complexity increases
Solution Approach 1:
The patent merges the protrusion structure with the encapsulant material itself, forming an integrated dome-shaped feature within the same material body. This eliminates the need for separate components or additional manufacturing steps, reducing device complexity while achieving the desired stray light refraction.
Solution Approach 2:
The patent changes the geometric parameter of the encapsulant material by introducing a domed surface with specific curvature radius and height. This parameter modification enables effective stray light refraction while maintaining compatibility with existing manufacturing processes and materials.
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 design significantly enhances the contrast and resolution of the optical encoder, maintaining high performance even at higher resolutions by preventing stray light from reaching the detector.
Implementation Method 1
The protrusion defines at least one surface that refracts stray light from the emitter away from the detector
Implementation Method 2
The first lens concentrates or directs the emitted light toward the code scale
Implementation Method 3
The second lens concentrates or directs the reflected light toward the optical detector
Implementation Method 4
The optical emitter emits light impinging on and reflecting from the code scale
Data Source
AI summary
An optical encoder includes an emitter, a first lens, a detector, a second lens, and a protrusion. The emitter emits light which is directed by the first lens to a code scale for reflection. The reflected light is directed by the second lens to the detector. The detector detects the reflected light from the code scale. The protrusion is between the first lens and the second lens. The protrusion defines at least one surface that refracts stray light from the emitter away from the detector. Accordingly, the stray light does not reach the detector; thus the detector can operate more effectively.