Circuitry for Counting Error Detection in Position Encoders
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Solution Overview
Problem
Multiturn rotary encoders face counting errors due to noise and interference, which cannot be detected from the signals of phase A and phase B, leading to incorrect counting and potential large numerical errors in position control data.
Innovation Solution
A circuit arrangement that generates doubled, tripled, or quadrupled base signals for counting, using a comparator to compare counter output signals with derived comparison signals to detect counting errors, thereby outputting an error signal when a specific relationship exists.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If counting is performed using only phase A or phase B switching edges, then the counting circuit is simple, but counting errors due to noise or interference cannot be detected
Solution Approach 1:
The patent introduces a comparator as an intermediary component that compares the counter output signal with a comparison signal derived from the base signal. This comparator acts as a mediator to detect counting errors by identifying discrepancies between the counted value and the expected value, thereby improving reliability without significantly increasing circuit complexity
Solution Approach 2:
The patent implements a feedback mechanism where the counter output signal is fed back to the comparator, which then compares it with the comparison signal. This feedback loop enables continuous monitoring of counting accuracy and automatic detection of errors, resolving the contradiction between simple circuit design and reliable counting
2Reliability
If doubled, tripled or quadrupled base signals are used for counting, then counting errors can be detected, but the circuit complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-processing the base signal to generate comparison signals at doubled, tripled, or quadrupled frequencies before the counting process. This preparation enables the comparator to detect counting errors more effectively, as the comparison signals are already in the appropriate form for error detection, reducing the overall circuit complexity
Solution Approach 2:
The patent changes the frequency parameter of the base signal by generating doubled, tripled, or quadrupled versions. This parameter change enables the system to detect counting errors by comparing the counter output with these modified signals, achieving improved reliability with minimal additional circuitry
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 allows for the detection of counting errors during measurement with high reliability through minor circuit changes, ensuring accurate position measurement by determining the logical relationship between counter output signals and base signals, thus preventing miscounts.
Implementation Method 1
a magnetic encoder that determines the number of revolutions completed. The optical absolute encoder for determining the absolute angle within a revolution consists, among other things, of a code disk attached to a shaft, a light-emitting diode to irradiate the code disk, a photodiode arrangement of a light receiving element which receives the light from the light-emitting diode via a scanning plate
Implementation Method 2
a light-emitting diode to irradiate the code disk, a photodiode arrangement of a light receiving element which receives the light from the light-emitting diode via a scanning plate
Data Source
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AI summary
The invention relates to a circuit arrangement and a method for detecting counting errors in a position measuring device that detects a pulse series corresponding to the position displacement of an object to be measured, wherein a counter (4) counts counting signals generated from at least one doubled, tripled, or quadrupled base signal (phase A, phase B) for calculating the position displacement, and a comparator (6) compares at least one output signal (Z0, Z1) of the counter (4) with a comparison signal derived from the at least one base signal (phase A, phase B). If a certain relationship exists, the comparator (6) outputs a counting error output signal (E).