Batteryless Rotary Encoder Using Piezoelectric Energy Harvesting
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Solution Overview
Problem
Conventional rotary encoders in machine tools rely on backup batteries for power, leading to increased production costs due to regular battery replacements when power is off.
Innovation Solution
A batteryless rotary encoder design utilizing a rotation detecting section with a rotational exciter magnet and a piezoelectric transducer, which generates a signal for a counter and rectifier to calculate rotations, eliminating the need for batteries by harnessing magnetic energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a backup battery is used in conventional encoders, then the encoder can maintain operation when power is off, but production costs increase due to regular battery replacements
Solution Approach 1:
The piezoelectric transducer generates electrical energy from the mechanical rotation of the exciter magnet, allowing the encoder to power itself without external batteries. The system converts the kinetic energy of rotation directly into electrical energy through the piezoelectric effect, eliminating the need for battery replacement while maintaining operational reliability
Solution Approach 2:
The patent replaces the chemical energy storage system (battery) with a mechanical-to-electrical energy conversion system (piezoelectric transducer). The piezoelectric elements convert mechanical rotation into electrical signals and power, substituting the battery-based power supply with a regeneration-based power system
2Ease of manufacture
If a piezoelectric transducer is used to generate power, then battery replacement is eliminated, but the device complexity increases
Solution Approach 1:
The piezoelectric transducer performs multiple functions simultaneously: it generates position detection signals for rotation measurement and generates electrical power to drive the encoder circuitry. This multi-functionality reduces the need for separate battery components while managing system complexity
Solution Approach 2:
The patent combines the signal generation function and power generation function into a single piezoelectric transducer component. The same piezoelectric elements that detect rotational position also generate the electrical energy needed to power the encoder, merging two functions into one integrated system
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 enables continuous operation without battery replacement, reducing production costs and maintaining accurate positioning in machine tools by using piezoelectric transducers to generate power for the encoder.
Implementation Method 1
The piezoelectric transducer is constructed by laminating a magnetic material and a piezoelectric transduction sheet, and the magnetic material faces toward the rotational exciter magnet. When the rotational exciter magnet rotates, the rotational exciter magnet attracts or repels the magnet sheet or the magnetic metal sheet so that the piezoelectric transducer is pressed or stretched by the magnet sheet or the magnetic metal sheet to generate a first output signal.
Data Source
AI summary
A batteryless rotary encoder is provided, which includes a rotation detecting section and a signal processing section. The rotation detecting section includes a rotational exciter magnet and a piezoelectric transducer. The piezoelectric transducer is constructed by laminating a magnetic material and a piezoelectric transduction sheet, and the magnetic material faces toward the rotational exciter magnet. When the rotational exciter magnet rotates, the rotational exciter magnet attracts or repels the magnet sheet or the magnetic metal sheet so that the piezoelectric transducer is pressed or stretched by the magnet sheet or the magnetic metal sheet to generate a first output signal. The signal processing section includes a counter and a rectifier. The counter receives the first output signal and calculates revolutions of the first output signal to indicate the number of rotations of the rotational exciter magnet. The rectifier receives the first output signal to power the counter.