Piezoelectric Speaker Drive Circuits for Smaller Charging Cases
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Solution Overview
Problem
Existing driving circuits for piezoelectric speakers in charging cases are suboptimal, leading to increased physical size, high power consumption, and degraded audio quality, which negatively impact user experience and the usability of finder features.
Innovation Solution
An improved driving circuit utilizing a DC voltage source, inductor, diode, and microcontroller to control the charging and discharging of the piezoelectric speaker, allowing for volume and frequency control, and enabling a smaller inductor design to conserve space and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If existing driving circuits are used for piezoelectric speakers, then the speaker can function, but the charging case size increases and power consumption increases
Solution Approach 1:
The patent optimizes the inductor value parameter to 100-500uH, which is smaller than conventional designs. This parameter change enables both reduced case size and reduced power consumption by improving the efficiency of the piezoelectric speaker driving circuit.
2Reliability
If existing driving circuits are used for piezoelectric speakers, then the speaker can function, but audio quality is degraded
Solution Approach 1:
The patent incorporates feedback control mechanisms in the driving circuit that monitor and adjust the electrical signals driving the piezoelectric speaker. This feedback ensures optimal performance and high audio quality while maintaining circuit simplicity through intelligent control algorithms.
3Volume of moving object
If the inductor size is reduced to conserve space, then charging case size decreases, but power consumption may increase
Solution Approach 1:
The patent identifies the optimal inductor parameter range of 100-500uH that simultaneously achieves small physical size and low power consumption. This precise parameter optimization resolves the trade-off between inductor size and power efficiency in the charging case circuit.
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 improved circuit enhances audio quality, reduces the charging case's size and temperature, and increases battery life, thereby improving user experience and the functionality of finder features.
Implementation Method 1
By toggling the first switch to a closed position, the MCU configures the improved driving circuit as a closed loop including the DC voltage source, the inductor, and the first switch. In this configuration, energy from the DC voltage source is transferred and stored by the inductor.
Implementation Method 2
The piezoelectric speaker is connected between the cathode of the diode and the ground plane. By toggling the second switch to a closed position while the first switch is in the open position, the MCU configures the improved driving circuit as a closed loop including the DC voltage source in series with the diode, the second switch in parallel with the piezoelectric speaker, and the ground plane. In this configuration, the voltage across the piezoelectric speaker is discharged into the ground plane and the piezoelectric speaker sounds.
Data Source
AI summary
This document describes improved driving circuits for piezoelectric speakers (piezos). In aspects, a charging case for a hearable device includes a piezo and a circuit for driving the piezo having a battery, an inductor, first and second switches, and a microcontroller. The microcontroller is configured to first toggle the first switch for a number of times to charge the piezoelectric speaker via the inductor to a target voltage level and second toggle the second switch to discharge and thus sound the piezo. In such aspects, the first toggling of the first switch and the second toggling of the second switch control a volume and frequency, respectively, of the sounding, improving audio quality and providing finder features to users. Further, charging the piezoelectric speaker via the inductor enables the inductor to be smaller, conserving space within and power consumption of the charging case, leading to improved battery life.