Digital Speaker Using Piezoelectric Element with Multiple Electrodes
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Solution Overview
Problem
Existing digital speakers face challenges in achieving high sound quality while being miniaturized, due to issues such as mutual induction between coils and differences in frequency characteristics caused by separate sound generating devices for each bit of the digital signal, and difficulties in applying voltage uniformly to piezoelectric elements.
Innovation Solution
A digital speaker system that divides input digital signals into bit units using a signal division circuit and outputs voltage through D/A converters to a single piezoelectric element with multiple electrodes, where the same voltage is applied to all electrodes, ensuring uniform frequency characteristics and eliminating mutual induction issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If separate sound generating devices are used for each bit of digital signal, then sound quality can be controlled, but mutual induction between coils occurs and device size increases
Solution Approach 1:
The patent merges multiple separate sound generating devices into a single piezoelectric element with multiple electrodes. Instead of using separate voice coils for each bit, the invention applies voltage to different regions of one piezoelectric element, eliminating mutual induction between coils while maintaining the ability to control sound quality for each bit.
Solution Approach 2:
The patent replaces the electromagnetic system (voice coils) with a piezoelectric system. The piezoelectric element converts electrical voltage directly into mechanical vibration without requiring magnetic fields, thereby eliminating the mutual induction problem inherent in electromagnetic coils while maintaining sound generation capability.
2Manufacturing precision
If multiple separate sound generating devices are used, then bit control is achieved, but miniaturization becomes difficult
Solution Approach 1:
The patent combines multiple bit control functions into a single piezoelectric element by providing multiple electrodes or electrode regions on one element. This allows the system to maintain fine-grained bit control while using a single compact component instead of multiple separate devices, thereby enabling miniaturization.
Solution Approach 2:
The patent transitions from a spatial arrangement of multiple separate devices to a two-dimensional arrangement of multiple electrodes on a single piezoelectric element surface. This dimensional change allows multiple bit controls to be integrated into a compact planar structure, facilitating miniaturization while preserving control precision.
3Manufacturing precision
If voltage is applied separately to central and circumferential portions of piezoelectric element, then bit control is achieved, but frequency characteristics become non-uniform
Solution Approach 1:
The patent applies different voltage control strategies to different regions (central and circumferential portions) of the piezoelectric element based on their specific acoustic characteristics. By tailoring the voltage application to match the local resonant properties of each region, the system achieves uniform frequency characteristics across the entire element while maintaining bit control capability.
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 allows for a miniaturized digital speaker with improved sound quality, capable of functioning as both a tweeter and woofer, and when integrated into earphones, provides high sound quality across various frequency bands without unit-to-unit differences in sound quality or mutual induction problems.
Implementation Method 1
one piezoelectric element including n electrodes, spaced apart from each other, for receiving the voltage output from the D/A converters
Data Source
AI summary
A digital speaker (1) is provided that is equipped with a piezoelectric element (4) including n electrodes (51, 52, 53) spaced apart from one another. Sound pressure is adjusted according to the surface area of the electrodes (51, 52, 53), and all the electrodes (51, 52, 53) can be driven by the same voltage. A speaker system is provided that uses the digital speaker (1) as a tweeter (11), or as all the speakers including a woofer (13). By this speaker system, earphones (8) are provided that are miniaturized and have high sound quality.