Flexible Encoder Scale for Displacement Detection Accuracy
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Solution Overview
Problem
Existing displacement detection encoders, such as optical encoders, suffer from reduced accuracy due to scale deflection and deformation caused by environmental changes like temperature and humidity, leading to errors in detection position and rotational angle.
Innovation Solution
The encoder design incorporates a flexible scale with a signal detection effective region and holding regions, where the stiffness of the holding regions is lower than the signal detection region, allowing for elastic deformation and absorption of expansion or contraction, maintaining the shape of the signal detection region and preventing significant position detection errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the scale is fixed rigidly to the cylindrical body, then the scale maintains its shape under normal conditions, but the scale deflects or deforms when environmental changes cause expansion or contraction
Solution Approach 1:
The scale is divided into a signal detection effective region (first region) and holding regions (second regions) at both ends. The holding regions have different stiffness characteristics from the signal detection region, allowing them to absorb expansion or contraction while the signal detection region maintains its shape for accurate detection.
Solution Approach 2:
Different regions of the scale are given different stiffness properties. The holding regions at both ends have lower stiffness to accommodate environmental expansion/contraction, while the signal detection effective region maintains higher stiffness and shape stability to ensure accurate optical path detection.
2Adaptability or versatility
If the scale is made flexible to accommodate environmental changes, then the scale can expand or contract, but the signal detection region may deform and cause detection errors
Solution Approach 1:
The scale is segmented into functional zones: holding regions at the ends that are more flexible to accommodate environmental changes, and a signal detection effective region in the middle that maintains shape stability for precise optical detection.
Solution Approach 2:
The scale exhibits local quality differentiation where the holding regions have different mechanical properties (lower stiffness) compared to the signal detection effective region (higher stiffness), allowing each region to perform its specific function optimally.
3Ease of manufacture
If the scale is attached using screw members with decentered center axes, then the scale can be attached even when length varies from design value, but the scale surface deforms under environmental stress
Solution Approach 1:
The scale attachment structure is segmented into holding regions at both ends that can accommodate length variations and environmental stress, while the signal detection effective region maintains surface accuracy independent of manufacturing tolerances.
Solution Approach 2:
The holding regions are designed with different mechanical characteristics to absorb manufacturing variations and environmental stress, protecting the signal detection effective region from deformation and ensuring consistent detection precision.
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 ensures high accuracy in displacement detection even under environmental changes, reducing the influence of scale deformation and maintaining surface accuracy, thus providing a reliable encoder across a wide range of conditions.
Implementation Method 1
an elastic member (11) is provided on at least one of the holders (12, 13). Therefore, one end of the scale (2) is capable of moving by at least predetermined amount in the circumferential direction. The elastic member (11) is configured so that the stiffness of the elastic member (11) in the circumferential direction of the cylindrical body (10) is smaller than the stiffness of the scale (2)
Implementation Method 2
the optical encoder is configured by including a light source, a scale that can be displaced relative to the light source, and a light receiving element that receives light that is reflected on or transmits through the scale
Implementation Method 3
a light receiving element that receives light that is reflected on or transmits through the scale
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3~4
AI summary
An encoder (100) includes a cylindrical body (10), a sensor unit (7) configured to detect a displacement of the cylindrical body (10) in a circumferential direction of the cylindrical body (10), and a scale (2) that is attached to the cylindrical body (10) using a holder (12) and a holder (13) and that has a signal detection effective region (14) used to detect the displacement by the sensor unit (7), and a region (17) that has a stiffness smaller than a stiffness of the signal detection effective region (14) in the circumferential direction of the cylindrical body (10) is provided on an outside of the signal detection effective region (14) and on at least one side of the first holder (12) and the second holder (13).