Voice Coil Motor Temperature Estimation With Inaudible Measurement Waves
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Solution Overview
Problem
Existing temperature estimation systems for voice coil motors, which can output audible sound, face challenges in accurately estimating temperature while minimizing unintended vibration sensations for users and optimizing processor load.
Innovation Solution
A system that generates a measurement wave below the audible range, superimposes it on control data for the voice coil motor, processes current and voltage values with a low-pass filter, and calculates resistance to estimate temperature, with adaptive filter order changes based on temperature and processor load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a measurement wave is used for temperature estimation in a voice coil motor that can output audible sound, then temperature estimation is achieved, but unintended vibration sensation is given to the user
Solution Approach 1:
The patent changes the frequency parameter of the measurement wave to be below the audible range (lower than 20 Hz). This parameter change allows the measurement wave to be used for temperature estimation without causing unintended vibration sensation to the user, as frequencies below 20 Hz are not perceptible as sound or vibration to human users.
2Measurement precision
If a low-pass filter with high order is used to process current and voltage values, then temperature estimation accuracy is improved, but processor load increases
Solution Approach 1:
The patent applies partial action by using a low-pass filter with an order that is sufficient to remove measurement wave components but not excessively high. The filter order is optimized to provide adequate temperature estimation accuracy while avoiding unnecessary computational burden on the processor. This means using just enough filtering capability to achieve the measurement goal without adding excessive complexity.
3Object-affected harmful factors
If the measurement wave frequency is set very low to avoid audible range, then user vibration perception is reduced, but temperature estimation accuracy may deteriorate
Solution Approach 1:
The patent optimizes the measurement wave frequency parameter to be below the audible range (lower than 20 Hz) but not excessively low. This frequency range is carefully selected to be imperceptible to users while still providing sufficient signal characteristics for accurate temperature estimation through resistance calculation. The frequency is high enough to maintain measurement sensitivity but low enough to avoid user perception.
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
Accurately estimates temperature with reduced user-perceptible vibration and lower processor load, enabling effective control of voice coil motor vibration based on estimated temperature.
Implementation Method 1
a voice coil motor 206 implemented by a linear motor
Implementation Method 2
low-pass filter means configured to subject the obtained current value and voltage value to low-pass filter processing
Implementation Method 3
resistance value calculation means configured to calculate a resistance value inside the voice coil motor based on the low-pass filtered current value and voltage value
Data Source
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AI summary
A computer-implemented method is provided. The method includes generating a measurement wave at a frequency lower than an audible range, the measurement wave being to be used for estimation of a temperature, generating superimposed control data by superimposing the measurement wave on control data for vibration of a voice coil motor, inputting the superimposed control data to the voice coil motor, obtaining a current value and a voltage value inside the voice coil motor to which the superimposed control data has been inputted, subjecting the obtained current value and voltage value to low-pass filter processing, calculating a resistance value inside the voice coil motor based on the low-pass filtered current value and voltage value, and estimating the temperature inside the voice coil motor based on the calculated resistance value.