Encoder Signal Weighting for Contamination Resilience
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Solution Overview
Problem
Encoders with displaceable detection heads face reduced signal detection efficiency due to contamination, leading to potential error stops in controlling machines, especially when integrated patterns on the scale are affected, causing positioning issues and machine stoppages.
Innovation Solution
The encoder employs a processor to calculate and combine position signals from detection array portions, using weighting coefficients based on signal strength, such as absolute differences or sinusoidal curve fitting, to maintain detection accuracy and compact head design, avoiding error stops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the detection area on the scale is widened to reduce the percentage of contaminated area, then the signal detection efficiency is maintained, but the size of the detection head is increased
Solution Approach 1:
The patent changes the parameter of signal processing by introducing weighted averaging based on signal strength. Instead of simply expanding the detection area, the system processes existing signals with different weights according to their strength, thereby maintaining detection accuracy without increasing the physical size of the detection head.
Solution Approach 2:
The patent replaces the mechanical approach of enlarging the detection head with a signal processing approach. By using weighted averaging algorithms, the system achieves improved reliability through computational methods rather than physical expansion, substituting mechanical design changes with electronic signal processing.
2Reliability
If error determination is performed on signals from light receiving array portions and erroneous signals are eliminated, then signal detection efficiency is maintained, but all signals may be eliminated in severe contamination cases causing error stops
Solution Approach 1:
The patent converts the harmful effect of contaminated areas into a beneficial weighting mechanism. Instead of eliminating signals from contaminated regions entirely, the system uses signal strength as a basis for weighting, where contaminated signals naturally receive lower weights. This transforms the problem of contamination into a feature for automatic signal quality assessment.
Solution Approach 2:
Rather than completely eliminating signals that might contain errors, the patent applies partial action by using weighted averaging. All signals are retained but contribute differently to the final result based on their strength, allowing the system to maintain operation even when some signals are degraded, avoiding complete shutdown while still filtering out poor quality data.
3Measurement precision
If the detection head is elongated to include more light receiving array portions, then positioning accuracy is maintained under contamination, but the detection head size is increased
Solution Approach 1:
The patent maintains positioning accuracy by changing the parameter of signal combination from simple averaging to weighted averaging based on signal strength. This allows the system to achieve the same measurement precision with a compact detection head configuration, as the weighting algorithm compensates for signal degradation without requiring additional detection elements.
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 approach suppresses detection accuracy reduction, maintains a compact detection head, and prevents error stops in controlling machines, even with contamination or integrated patterns on the scale, ensuring consistent and reliable positioning.
Implementation Method 1
a photoelectric encoder will be exemplarily described... signal detection efficiency of light receiving array portions arranged in a detection head
Data Source
Figure 1~2B
Figure 3A~3C
Figure 4
AI summary
A detection head includes a plurality of detection array portions that are arranged in a direction along which the head is relatively displaceable. Position signals indicating a position of the detection head are calculated from output signals output from the detection array portions. In order to combine the position signals with one another and determine the position of the detection head with respect to the scale, weighting according to a level of the output signal is performed on the position signal of each of the detection array portions, and the weighted position signals are averaged.