Encoder Readhead Signal Combining for Compact Position Measurement
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Solution Overview
Problem
Existing magnetic encoder systems require separate sensors for absolute and incremental position measurements, leading to a bulky readhead and reduced reliability in data extraction.
Innovation Solution
A readhead with multiple sensors that combine signals using signal combiners to generate both absolute and incremental position information, eliminating the need for additional sensors and improving data extraction reliability by weighting combined sensor signals to reduce harmonic effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate sensors are used for absolute and incremental position measurements, then measurement precision is improved, but device complexity and readhead size increase
Solution Approach 1:
The patent combines absolute and incremental position measurement functions into a single readhead by using one set of sensors to read both types of data from the scale. The signal processing system combines sensor signals to generate both absolute position codes and incremental position signals simultaneously, eliminating the need for separate sensor arrays while maintaining high measurement precision.
Solution Approach 2:
The readhead is designed with multi-functionality where a single sensor array performs multiple measurement tasks. The same sensors that read absolute position data also contribute to generating incremental position signals through signal combination and processing, making the readhead universally capable of both measurement types without requiring additional dedicated sensors.
2Reliability
If multiple sensors are used for reliable data extraction, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent uses signal combiners to merge sensor signals in a way that enhances reliability. By combining signals from multiple sensors through weighted summation and differentiation, the system achieves more reliable data extraction while keeping the physical sensor array compact and manageable.
Solution Approach 2:
The system employs feedback mechanisms where the extracted absolute position information is used to guide the interpretation of incremental signals. This feedback loop ensures reliable data extraction by continuously validating and adjusting the position measurements based on the combined sensor signal analysis.
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
The solution provides improved absolute data extraction reliability and compact design by using combined sensor signals for both absolute and incremental measurements, offering higher resolution and reduced subdivisional error.
Implementation Method 1
the varying magnetic properties of an associated scale are read by a readhead that comprises one or more magnetic (e.g. Hall) sensors
Implementation Method 2
magnetic (e.g. Hall) sensors
Data Source
AI summary
A readhead is provided for reading an absolute scale, optionally a passive magnetic scale, that encodes a series of data bits. The readhead includes a plurality of sensors, such as an array of Hall sensors, for producing a plurality of sensor signals. A plurality of signal combiners are also provided to receive at least two of the sensor signals and produce therefrom a combined sensor signal. A plurality of data bit extractors are arranged to receive at least two combined sensor signals and to determine the value of a data bit encoded in an associated absolute scale. The readhead also comprises an incremental signal generator for generating at least one incremental signal from the combined sensor signals produced by a plurality of the signal combiners. In this manner, both absolute and incremental position is measured.