Encoder Origin Detection Circuit for Stable DC-Shift Compensation
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Solution Overview
Problem
Conventional origin location detection circuits in encoders face reproducibility issues due to fluctuations in the DC component of the output voltage signal, particularly affected by LED and phototransistor degradation, ambient temperature changes, and power-supply voltage fluctuations, leading to detection location deviations.
Innovation Solution
An origin location detection circuit incorporating a DC voltage detection circuit with a low pass filter and a differential amplifier circuit, where the differential amplifier signal is input to a comparator, effectively smoothing the output voltage signal and eliminating DC component fluctuations, thereby improving reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional origin location detection circuit is used, then the circuit is simple, but the detection location reproducibility deteriorates due to DC component fluctuation
Solution Approach 1:
A DC voltage detection circuit is introduced as an intermediary component to detect and process the DC component of the output voltage signal separately. This intermediary circuit generates a DC voltage signal that is then used by the differential amplifier circuit to compensate for DC fluctuations, thereby improving detection location reproducibility without significantly increasing overall system complexity
Solution Approach 2:
The invention changes the parameter being monitored by the comparator from the raw output voltage signal to a differential amplifier signal that has had its DC component removed. By transforming the signal parameter (from voltage level to differential signal), the system achieves improved reproducibility against DC fluctuations while maintaining reasonable circuit complexity
2Measurement precision
If DC component fluctuation is compensated, then detection location reproducibility improves, but device complexity increases
Solution Approach 1:
The DC voltage detection circuit and differential amplifier circuit are merged into a unified signal processing path that works together with the existing comparator. Rather than adding completely separate compensation systems, the invention integrates DC detection and differential amplification into the existing origin detection signal path, achieving compensation with minimal additional complexity
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 significantly enhances the reproducibility of the origin signal detection location by stabilizing the DC component, reducing detection location deviations even under conditions of LED and phototransistor degradation, temperature changes, and power-supply fluctuations.
Implementation Method 1
a DC voltage detection circuit smoothing the output voltage signal
Implementation Method 2
a differential amplifier circuit performing differential amplification of the output voltage signal and a DC voltage signal output from the DC voltage detection circuit
Implementation Method 3
when an LED as a light source and a phototransistor as a light receiver (detector) are used
Data Source
AI summary
An origin location detection circuit in an encoder. The encoder includes a scale on which an origin pattern indicating an origin is provided and a detection head relatively displaceable with respect to the scale. The origin location detection circuit includes a comparator for generating an origin signal indicating a location of the origin from an output voltage signal, which is output from a detector of the detection head and has been affected by involvement of the origin pattern; a DC voltage detection circuit smoothing the output voltage signal; and a differential amplifier circuit performing differential amplification of the output voltage signal and a DC voltage signal output from the DC voltage detection circuit. A differential amplifier signal of the differential amplifier circuit is input to the comparator.