Encoder Slit Row Design for Rotation and Eccentricity Measurement
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Solution Overview
Problem
Existing encoder systems face challenges in accurately measuring both the rotation amount and eccentricity of a disc without increasing the size of the encoder, as they typically require separate patterns and external sensors for eccentricity measurement.
Innovation Solution
The encoder system incorporates a disc with slit tracks having repetition patterns in both the circumferential and radial directions, utilizing a single optical module with light receiving arrays to measure rotation amount and eccentricity, eliminating the need for external sensors and separate tracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate patterns and external sensors are used for eccentricity measurement, then measurement capability is improved, but encoder size increases
Solution Approach 1:
The patent combines the rotation amount measurement function and eccentricity measurement function into a single encoder structure. The same slit row and light receiver are used to detect both the rotational position and the radial displacement caused by eccentricity, eliminating the need for separate sensors and patterns.
Solution Approach 2:
The slit row serves multiple functions: it measures both the rotation amount through circumferential position detection and the eccentricity through radial position detection. The light receiver similarly performs dual detection of rotational and radial movements, achieving multi-functionality with a single component.
2Measurement precision
If separate patterns are used for rotation and eccentricity measurement, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the measurement functions for rotation and eccentricity into a unified detection system. A single slit row with specific geometric configuration enables both measurement types simultaneously, reducing the number of components and simplifying the overall structure.
Solution Approach 2:
The patent utilizes changes in the detection parameters by analyzing different aspects of the same detection signal. The light receiving signal contains information about both circumferential position (rotation) and radial position (eccentricity), which are extracted through different processing methods from the same signal source.
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 allows for accurate internal measurement of both rotation amount and eccentricity, reducing the encoder's size and complexity while maintaining high measurement resolution.
Implementation Method 1
The sensor has a first light receiver and a second light receiver. The first light receiver is configured to output a first light receiving signal as the slit row rotates along the circumferential direction when the disc rotates around the central axis. The second light receiver is configured to output a second light receiving signal as the slit row moves along the radial direction when the disc rotates around the central axis.
Data Source
AI summary
An encoder includes a disc and a sensor. The disc has a circular surface with a central axis and is rotatable around the central axis. The disc has a slit row provided on the circular surface. The slit row includes slits arranged in a circumferential direction of the circular surface around the central axis and in a radial direction of the circular surface. The sensor is provided opposite to the slit row on circular surface. The sensor has a first light receiver and a second light receiver. The first light receiver is configured to output a first light receiving signal as the slit row rotates along the circumferential direction when the disc rotates around the central axis. The second light receiver is configured to output a second light receiving signal as the slit row moves along the radial direction when the disc rotates around the central axis.