Optical Encoder Origin Detection Scale Grid Pattern
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical encoders face challenges in accurately detecting the origin point position due to high manufacturing costs and reduced accuracy in three-grid configurations, where interference fringes from multiple grid portions can complicate the detection process.
Innovation Solution
An optical encoder design featuring an origin point detection scale with both a reference and inverse pattern, along with a light source and photoreceiver grid, where light emission and blocking portions are arranged in specific patterns to enhance accuracy by phase alignment and interference fringe management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a two grid configuration is used with main scale, read-out scale, and light source positioned with high accuracy, then origin point position detection accuracy is improved, but manufacturing costs are magnified and become expensive
Solution Approach 1:
The invention divides the scale into two separate scales: a main scale with first and second grid portions for general measurement, and a dedicated origin point detection scale with third and fourth grid portions for origin detection. This segmentation allows each scale to be optimized independently, reducing the need for high-precision positioning of all components relative to each other, thereby lowering manufacturing costs while maintaining detection accuracy.
Solution Approach 2:
The invention introduces a light source grid as an intermediary element positioned between the light source and the origin point detection scale. This light source grid acts as a mediator that facilitates the generation of interference fringes without requiring the light source to be positioned with extremely high accuracy, thus reducing manufacturing costs while maintaining origin point detection accuracy.
2Measurement precision
If a three grid configuration is added with light source grid to increase position detection accuracy using interference fringe, then position detection accuracy is improved, but interference fringes from multiple grid portions complicate detection and may reduce origin point position detection accuracy
Solution Approach 1:
The invention segments the grid structures into functionally distinct groups: the first and second grid portions on the main scale for general position measurement, and the third and fourth grid portions on the origin point detection scale for origin detection. This functional segmentation allows the interference fringes from different grid portions to be spatially and functionally separated, reducing detection complexity while maintaining high position detection accuracy.
Solution Approach 2:
The invention applies different grid configurations to different regions of the optical system. The main scale uses a specific grid pitch for general measurement, while the origin point detection scale uses a different grid pitch optimized for origin detection. This local optimization of grid properties reduces interference between different measurement functions and simplifies the detection process.
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 allows for precise detection of the origin point position with improved accuracy and reduced manufacturing costs by optimizing the arrangement of light and dark regions in the grid patterns, enhancing signal strength and reducing noise.
Implementation Method 1
The optical encoder having the three grid configuration detects a position using an interference fringe
Implementation Method 2
a photoreceiver detecting light from the origin point detection scale
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An optical encoder (1) includes an origin point detection scale (10) having an origin point detection pattern and an inverse origin point detection pattern that is the inverse of the origin point detection pattern; a light source (14) emitting light at the origin point detection scale (10); a light source grid (11) that is inserted on the light source side of the origin point detection scale, the light source grid having two first light source grid patterns corresponding to the origin point detection pattern and the inverse origin point detection pattern, respectively; a photoreceiver (12) detecting a signal from light that has passed through the origin point detection scale; and a photoreceiver grid (13) inserted on the photoreceiver side of the origin point detection scale, the photoreceiver grid having two first photoreceiver grid patterns that are a pattern either identical to or the inverse of the first light source grid pattern.