Optical Encoder Scale Light Guiding Reflection Surfaces
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Solution Overview
Problem
The Talbot or triple grating encoder has limited flexibility in arranging the light projecting, scale, and light receiving portions, restricting the ability to miniaturize the encoder due to the need for precise alignment for interference pattern detection.
Innovation Solution
Incorporating a scale with a light guiding function that allows light to be transmitted through it, enabling the light receiving portion to move relative to the scale and increasing the freedom in arranging the light projecting, scale, and light receiving portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Talbot encoder or triple grating encoder is used to achieve high measurement precision, then measurement precision is improved, but the degree of freedom in arranging the light projecting portion, scale, and light receiving portion is reduced
Solution Approach 1:
The scale is divided into a first scale with transmission slits and a second scale with reflection surfaces. This segmentation allows the light receiving portion to detect signals from either transmission or reflection, providing flexibility in arrangement while maintaining measurement precision.
Solution Approach 2:
The scale is designed to perform multiple functions: it can transmit light through transmission slits and reflect light through reflection surfaces. This multi-functionality allows the same scale to work with different detection methods, increasing the degree of freedom in arranging the optical components.
2Measurement precision
If the light receiving portion is positioned at a fixed interval from the light source scale to detect the interference pattern, then measurement precision is improved, but the encoder cannot be further thinned
Solution Approach 1:
Instead of using only transmission detection with the light receiving portion positioned at a fixed interval, the invention inverts the approach by using reflection detection. The reflection surfaces on the second scale allow the light receiving portion to detect interference patterns from a different spatial configuration, enabling encoder thinning while maintaining measurement precision.
3Measurement precision
If the light receiving portion detects the interference pattern at a specific position, then measurement precision is improved, but the degree of freedom in arrangement is reduced
Solution Approach 1:
The second scale with reflection surfaces acts as an intermediary between the light source and the light receiving portion. It enables the light receiving portion to detect interference patterns without being constrained to a specific position, as the reflection surfaces can redirect light to the detector from various spatial configurations.
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 configuration enhances the degree of freedom in designing the optical encoder, allowing for a thinner and more flexible arrangement of the light projecting and receiving components while maintaining high-resolution displacement measurement.
Implementation Method 1
the light guiding portion has a light guiding function of guiding at least a part of the light projected by the light projecting portion in a direction perpendicular to the thickness direction thereof through the light guiding portion
Data Source
AI summary
An optical encoder includes a light projecting portion, a light receiving portion, and a scale arranged between the light projecting portion and the light receiving portion. The scale includes a light guiding portion which allows light to transmit therethrough and has a light guiding function of guiding at least a part of the light projected by the light projecting portion in a direction perpendicular to a thickness direction thereof through the light guiding portion. The light receiving portion receives the light guided by the scale and relatively moves with respect to the scale.