Optical Encoder Light Source Array Spacing for Noise Reduction
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Solution Overview
Problem
Existing optical encoders face challenges in reducing noise while maintaining detection precision and downsizing, particularly due to scattered light from protruding wires and other members, which affects the accuracy of position detection.
Innovation Solution
The encoder design incorporates a point light source with a light receiving array arrangement where the distance between the light source and the incremental signal light receiving arrays is shorter than that between the light source and the absolute signal light receiving arrays, effectively minimizing noise interference while maximizing light reception and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the distance between the light source and light receiving arrays is reduced to downsize the encoder, then the device size is reduced, but noise from scattered light increases and detection precision deteriorates
Solution Approach 1:
The patent applies local quality by assigning different distances to different light receiving arrays based on their specific functions. The incremental signal light receiving arrays are positioned closer to the light source for compactness, while the absolute signal light receiving arrays are positioned farther away to reduce noise interference. This differential positioning resolves the contradiction by optimizing each array's position according to its specific requirements rather than using a uniform distance.
Solution Approach 2:
The patent segments the light receiving function into two distinct arrays: one for incremental signals and another for absolute signals. This segmentation allows each array to be positioned at an optimal distance from the light source, with the incremental array closer for size reduction and the absolute array farther for noise reduction, thereby resolving the contradiction between downsizing and maintaining precision.
2Measurement precision
If the distance between the light source and light receiving arrays is increased to reduce noise interference, then detection precision is improved, but the device size increases
Solution Approach 1:
The patent implements local quality by positioning the absolute signal light receiving arrays at a greater distance from the light source compared to the incremental signal arrays. This localized adjustment ensures that noise-sensitive absolute signal detection occurs at optimal distances for precision, while the incremental detection maintains closer positioning to minimize overall device size.
Solution Approach 2:
By segmenting the detection function into two separate arrays, the patent enables differential positioning strategies. The absolute signal array is placed farther away to reduce noise interference and improve precision, while the incremental signal array remains closer to control device dimensions, thus resolving the size-precision contradiction.
3Device complexity
If a uniform distance is maintained between the light source and all light receiving arrays, then the structure is simplified, but noise interference increases and detection precision deteriorates
Solution Approach 1:
The patent applies local quality by assigning different distances to different light receiving arrays based on their specific functions. The incremental signal light receiving arrays are positioned closer to the light source, while the absolute signal light receiving arrays are positioned farther away. This differential positioning resolves the contradiction by optimizing each array's position according to its specific requirements rather than using a uniform distance.
Solution Approach 2:
The patent segments the light receiving function into two distinct arrays: one for incremental signals and another for absolute signals. This segmentation allows each array to be positioned at an optimal distance from the light source, with the incremental array closer for compactness and the absolute array farther for noise reduction, thereby resolving the contradiction between downsizing and maintaining 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 enhances detection precision and reduces noise, allowing for a more compact encoder design while maintaining accurate position detection, even in the presence of scattered light.
Implementation Method 1
a point light source configured to irradiate the part of the slit array with light, and a light receiving array comprising a plurality of light receiving elements arranged side by side along the measurement axis and arranged around the point light source in a plane parallel to the slit array, the light receiving elements being respectively receiving light irradiated from the point light source and reflected from the reflection slit
Data Source
AI summary
This disclosure discloses an encoder. The encoder includes a slit array and an optical module. The optical module includes a point light source and a light receiving array comprising a plurality of light receiving elements arranged side by side along the measurement axis and arranged around the point light source in a plane parallel to the slit array, the light receiving elements being respectively receiving light irradiated from the point light source and reflected from the reflection slit. The light receiving array includes a first light receiving array and a second light receiving array. The point light source, the first light receiving array and the second light receiving array are arranged in the manner that a shortest distance between the point light source and the first light receiving array is smaller than a shortest distance between the point light source and the second light receiving array.