Position Detection Using Center Voltage Ratio Computation

Solution Overview

Problem

Existing position detection technologies for moving bodies, such as motor rotors, face accuracy issues due to variations in rotation speed and slit shape, leading to unreliable amplitude-based position detection.

Innovation Solution

A position detecting device that computes a difference value and a ratio using center voltages of first and second detected signals with phase differences, allowing for accurate position specification of moving bodies by reducing reliance on voltage amplitude measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If position detection uses voltage amplitude (peak-to-peak value) of detected signals, then the detection method is simple, but the accuracy decreases due to variations in rotation speed and slit shape

Engineering Contradiction:

Improveposition detection accuracyVSAvoidcomputation complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The invention changes the parameter used for position detection from voltage amplitude (peak-to-peak value) to center voltage. This parameter substitution fundamentally resolves the accuracy issue caused by rotation speed and slit shape variations, as center voltage remains stable across different operating conditions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces the traditional amplitude-based detection mechanism with a center-voltage-based ratio computation system. By substituting the measurement approach and introducing ratio computation with sign determination, the system achieves higher accuracy without excessive complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If position detection uses center voltage-based ratio computation, then the accuracy improves, but the computational process becomes more complex

Engineering Contradiction:

Improveposition detection accuracyVSAvoidcomputation complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The invention changes the parameter used for position detection from voltage amplitude (peak-to-peak value) to center voltage. This parameter substitution fundamentally resolves the accuracy issue caused by rotation speed and slit shape variations, as center voltage remains stable across different operating conditions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces the traditional amplitude-based detection mechanism with a center-voltage-based ratio computation system. By substituting the measurement approach and introducing ratio computation with sign determination, the system achieves higher accuracy without excessive complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If the range of position is not limited by sign determination, then the position specification is simpler, but the accuracy decreases due to ambiguous position determination

Engineering Contradiction:

Improveposition detection accuracyVSAvoidposition specification simplicity

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The invention replaces the traditional amplitude-based detection mechanism with a center-voltage-based ratio computation system. By substituting the measurement approach and introducing ratio computation with sign determination, the system achieves higher accuracy without excessive complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention segments the position determination process into two stages: first determining the sign combination to identify the quadrant/range, then using ratio computation to specify the precise position within that range. This segmentation enables both high accuracy and clear operational simplicity.

Inventive Principle:

Principle #1Segmentation

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 enhances position detection accuracy and reduces computational load by using center voltage-based ratios, effectively mitigating errors caused by speed and shape variations, enabling precise position determination of rotating bodies.

Implementation Method 1

an optical rotary encoder in which a light-receiving element receives light that is transmitted through a plurality of disc slits

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentUS9784598B2Position detecting device, electronic apparatus, recording apparatus, robot, and position detecting method having a ratio computing unit

Publication Date: 2017.10.10 SEIKO EPSON CORP

AI summary

A position detecting device detects the position of a moving body by using first and second detected signals that have voltage values changing in connection with a movement of the moving body. The position detecting device includes a difference computing unit that computes first and second difference values, the first being the difference between a center voltage of the first detected signal and the voltage value of the first detected signal, and the second being the difference between a center voltage of the second detected signal and the voltage value of the second detected signal. A ratio computing unit computes a difference-sum ratio index in accordance with the ratio of the difference value between the absolute values of the first and second difference values and the absolute value of the second difference value to the sum of the absolute values of the first and second difference values.