Optical Scale Wire Patterns for High Resolution
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Solution Overview
Problem
Existing optical encoders face limitations in resolution due to the size of the rotating disk and are affected by fluctuations in detected light, requiring highly granular segments and increased numbers of half-wave plates or microscopic fan-shaped regions.
Innovation Solution
An optical scale with a continuous change in tangential directions of non-intersecting wires allows for polarization changes corresponding to light position, eliminating the need for granular segments and enabling higher resolution without increasing disk size, and can be manufactured through bulk-exposure or nanoimprinting for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of half-wave plates or microscopic fan-shaped regions is increased to improve resolution, then the resolution of the encoder is improved, but the size of the rotating disk must be increased
Solution Approach 1:
The optical scale is segmented into multiple wire patterns, each with different orientations. By dividing the scale into distinct wire pattern regions rather than using continuous granular segments, the patent achieves high resolution without proportionally increasing disk size. The segmented wire patterns create multiple detection channels that can be read simultaneously.
Solution Approach 2:
The patent transitions from one-dimensional linear scales to two-dimensional wire pattern arrays. By arranging wires in multiple orientations across the disk surface, the system encodes positional information in both radial and circumferential directions, effectively using another dimension to increase resolution without linearly increasing disk circumference.
2Measurement precision
If highly granular fan-shaped regions are provided to achieve accurate detection, then the detection accuracy is improved, but the device complexity increases
Solution Approach 1:
Different regions of the optical scale have different wire pattern orientations and densities optimized for their specific functional requirements. The wire patterns are arranged with varying local characteristics - some regions have denser patterns for higher resolution, while others have different orientations for specific detection purposes, allowing each local area to have the quality needed for its function.
Solution Approach 2:
The optical scale uses composite wire patterns combining multiple orientations and densities in a single structure. Rather than using uniform granular segments throughout, the patent creates a composite pattern where different wire arrangements work together to provide both high detection accuracy and simplified manufacturing compared to purely granular approaches.
3Temperature
If the size of the optical scale is reduced to improve heat resistance and compactness, then heat resistance and compactness are improved, but the resolution is degraded
Solution Approach 1:
The patent changes the fundamental parameters of the scale structure from traditional linear gratings to wire patterns with varying orientations and densities. This parameter change allows the system to maintain high information density (resolution) in a smaller physical footprint, as the wire patterns can encode multiple detection channels within the same area, effectively increasing the information capacity per unit area.
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
The solution achieves high resolution and heat resistance with reduced size, improved manufacturing stability, and increased tolerance to foreign substances, allowing for accurate position detection with reduced error.
Implementation Method 1
allows the polarization of the transmissive light or the reflected light to change correspondingly to the tangential directions of the respective wires
Data Source
AI summary
An optical scale, a method for manufacturing an optical scale, and an optical encoder. The optical scale includes a plurality of wires provided thereon so that the wires do not intersect each other and each of the tangential directions of the respective wires changes continuously. The optical encoder includes the optical scale, a light source, an optical sensor, and a computing unit. The optical sensor includes a first polarizing layer that splits incident light that is light source light from the light source passed through or reflected on the optical scale and being incident on the first polarizing layer to a first polarization direction, a second polarizing layer that splits the incident light to a second polarization direction, a first photoreceiver that receives first polarized light split by the first polarizing layer, and a second photoreceiver that receives second polarized light split by the second polarizing layer.