Optical Encoder Signal Processing Circuit for Position Detection
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Solution Overview
Problem
Existing optical encoder signal processing circuits face accuracy issues due to variations in power supply voltage and reference voltage, leading to reduced position detection precision, especially when using four-phase signals and external arithmetic operations.
Innovation Solution
A signal processing circuit configuration that includes a reference voltage generator, current/voltage converter, sample and hold circuit, and amplifier, where the sample and hold circuit holds both the voltage signal and reference voltage at the same point in time, ensuring the output signal is not affected by variations in the reference voltage, and using a simpler circuit design to maintain accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional signal processing circuit is used with separate sampling of voltage signal and reference voltage, then the circuit can process signals, but the position detection accuracy deteriorates due to reference voltage variations
Solution Approach 1:
The patent applies preliminary action by sampling and holding both the voltage signal and reference voltage at the same point in time before processing. The sample and hold circuit captures both signals simultaneously, ensuring that the reference voltage used for processing matches the voltage signal timing, thereby eliminating accuracy degradation caused by reference voltage variations.
2Device complexity
If the sample and hold circuit holds only the voltage signal without holding reference voltage, then the circuit is simpler, but the output signal accuracy deteriorates due to reference voltage variations
Solution Approach 1:
The patent merges the holding of voltage signal and reference voltage into a single sample and hold circuit operation. Both signals are sampled and held simultaneously at the same point in time, ensuring consistency between the voltage signal and its reference without requiring separate complex circuitry for each.
3Productivity
If different arithmetic operation timings are used for four-phase signals, then processing can be optimized, but position detection accuracy deteriorates due to reference voltage timing differences
Solution Approach 1:
The patent applies preliminary action by pre-sampling and holding both the voltage signal and reference voltage at a unified timing point before arithmetic operations. This ensures that regardless of when the arithmetic operations are performed for different phases, the reference voltage timing is consistent with the voltage signal timing, eliminating accuracy degradation.
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 achieves highly accurate position detection in optical encoders, independent of power supply voltage variations, with improved precision and reduced circuit complexity, while maintaining stability across different arithmetic operation timings.
Implementation Method 1
a photoreceiver receiving the light from the scale and outputting a signal corresponding to the received light
Data Source
AI summary
A reference voltage generator circuit generates a reference voltage corresponding to a power supply voltage. A current/voltage converter circuit converts a photocurrent output by a photoreceiver into voltage, and outputs a voltage obtained by adding the converted voltage and the reference voltage. A sample and hold circuit holds a voltage of a capacitor in response to a sample and hold signal, the capacitor having the voltage input at one end and the reference voltage input at another end. An amplifier circuit outputs an output signal where a voltage held by the sample and hold circuit is amplified with the reference voltage as a reference.