Absolute Encoder Layout for Misalignment-Resistant Phase Detection
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Solution Overview
Problem
Existing encoders face accuracy issues due to positional deviations of the sensor relative to the scale, leading to phase discrepancies between absolute signals, which affect the precision of position detection in servo systems.
Innovation Solution
The encoder configuration includes two light receiving arrays with alternately arranged light receiving elements outputting phase-shifted absolute signals, positioned across the optical axis to minimize the impact of positional deviations and improve detection accuracy by selecting signals from stable regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single light receiving array is used, then the device complexity is low, but the measurement precision deteriorates due to phase discrepancies caused by sensor misalignment
Solution Approach 1:
The light receiving array is divided into multiple independent light receiving elements (first light receiving elements and second light receiving elements) that are alternately arranged. Each element can independently detect light and generate signals, allowing the system to segment the detection function across multiple elements to achieve higher precision while managing complexity through modular design
Solution Approach 2:
Multiple light receiving elements are combined into a single integrated array structure that processes signals collectively. The alternately arranged first and second light receiving elements work together to generate phase-shifted signals, merging their individual detection capabilities into a unified measurement system that achieves high precision position detection
2Measurement precision
If light receiving elements are arranged alternately to reduce phase discrepancies, then the measurement precision improves, but the device complexity increases due to the complex arrangement and signal processing requirements
Solution Approach 1:
The first and second light receiving elements are arranged alternately in an asymmetric pattern relative to each other, creating intentional phase differences in their detection signals. This asymmetric arrangement is designed to generate complementary phase-shifted signals that can be processed to eliminate misalignment errors, improving precision while the systematic nature of the asymmetry keeps the complexity manageable
Solution Approach 2:
Instead of trying to perfectly align a single light receiving array, the invention inverts the approach by deliberately creating multiple elements with intentional phase differences, then using signal processing to cancel out the discrepancies. The alternately arranged elements generate opposite-phase signals that, when combined, eliminate the effects of sensor misalignment
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 the accuracy of absolute position detection by canceling phase discrepancies caused by sensor misalignment, thereby improving the reliability of position, speed, and acceleration measurements in servo systems.
Implementation Method 1
a first absolute light receiver configured to receive the light transmitted through or reflected on the first absolute pattern of the scale
Implementation Method 2
a first absolute light receiver configured to receive the light transmitted through or reflected on the first absolute pattern of the scale
Implementation Method 3
a plurality of first light receiving elements each configured to output a first absolute signal with a first phase when each of the plurality of first light receiving elements receives the light transmitted or reflected
Data Source
AI summary
An encoder includes a scale and a sensor. The scale has first and second absolute patterns. The sensor includes a light source, and first and second absolute light receivers. The first and second absolute light receivers receive light from the first and second absolute patterns, respectively. The first absolute light receiver receives light from the first pattern and includes first and second light receiving elements. Each first light receiving elements outputs a first signal with a first phase. Each second light receiving elements outputs a first signal with a second phase. The first and second light receiving elements are arranged alternately. The second absolute light receiver includes third and fourth light receiving elements. Each third light receiving element outputs a second signal with the first phase. The third and fourth light receiving elements are arranged alternately. Each fourth light receiving element outputs a second signal with the second phase.