Staggered Rotary Encoder Resolution via Segmented Wheels
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Solution Overview
Problem
Conventional rotary encoders face challenges in increasing measurement resolution without compromising mass production efficiency, as denser slot arrangements on encoder wheels complicate plastic injection molding and reduce yield.
Innovation Solution
The design incorporates staggered encoder wheels with coaxially disposed portions, each with distinct graduation features and positioning structures, allowing for increased resolution while using the same structure for both wheels, which can be manufactured with a single mold set, simplifying assembly and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If slots are arranged in a denser manner to increase measurement resolution, then measurement precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The encoder wheel is divided into multiple segments (first encoder wheel with first slots, second encoder wheel with second slots). Each segment can be manufactured separately with coarser slot spacing that is easier to mold, then assembled together to achieve the equivalent of dense slot arrangement for high measurement resolution.
Solution Approach 2:
Multiple encoder wheels with different slot patterns are nested coaxially on the same shaft. The first encoder wheel has slots at certain angular positions, while the second encoder wheel has slots at different angular positions. By combining the detection signals from both wheels, the system achieves higher effective resolution than either wheel alone, without requiring any single wheel to have densely spaced slots.
2Measurement precision
If slots are arranged in a denser manner to increase measurement resolution, then measurement precision is improved, but productivity deteriorates
Solution Approach 1:
The encoder wheel is divided into multiple segments (first encoder wheel with first slots, second encoder wheel with second slots). Each segment can be manufactured separately with coarser slot spacing that is easier to mold, then assembled together to achieve the equivalent of dense slot arrangement for high measurement resolution.
3Measurement precision
If different structure encoder wheels are used to achieve staggered effect, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The encoder wheel is designed with universal features that serve multiple functions: the positioning protrusions and positioning grooves are used both for precise angular alignment between wheels and for mechanical coupling to the shaft. The slot patterns on different wheels are designed to be complementary rather than identical, allowing each wheel to contribute uniquely to the measurement while maintaining a relatively simple individual structure.
Data Source
AI summary
A rotary encoder includes a rotating shaft, first and second encoder wheels, first and second detectors and a processor. The first encoder wheel includes coaxially disposed first and second portions. The first portion has first graduation features. The second portion has a first positioning structure. The second encoder wheel includes coaxially disposed third and fourth portions. The third portion has second graduation features. The fourth portion has a second positioning structure meshing with the first positioning structure, so that the first graduation features and the second graduation features are staggered, and the first encoder wheel and the second encoder wheel are coaxially mounted on the rotating shaft. The first and second detectors detect the first and second graduation features and output first and second signals, respectively. The processor calculates a rotating angle of the rotating shaft according to the first and second signals.