Microprocessor Audio Transducer Drive Circuit
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Solution Overview
Problem
Piezoelectric transducers, such as benders, require precise drive frequencies and high voltages for maximum output, limiting flexibility in sound volume control and design, especially when used in audio transducers like coil speakers or polymer piezoelectric speakers.
Innovation Solution
A circuit using an energy-storing inductor and electronic switches, controlled by a microprocessor, generates pulses with adjustable rate and duty cycle to drive audio transducers, allowing for flexible control of sound tone and amplitude, and incorporating feedback mechanisms to optimize power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If piezoelectric benders are used to generate audio tones, then high audio output and reliability are achieved, but the circuit requires precise drive frequency and high voltage, limiting flexibility in sound volume control
Solution Approach 1:
The patent implements dynamic control of the piezoelectric transducer drive circuit through a microprocessor that can programmably adjust operating parameters including frequency, amplitude, and power level. This allows the system to adapt to different audio requirements while maintaining reliable operation of the piezoelectric elements.
Solution Approach 2:
The invention changes the operating parameters of the piezoelectric transducer by using a microprocessor to dynamically adjust drive frequency, amplitude, and power delivery. This enables flexible sound volume control and different audio outputs while maintaining the reliability benefits of piezoelectric technology.
2Power
If bridge drivers, step-up transformers, or flyback mode inductors are used to achieve high voltages across piezoelectric devices, then high output sound levels are generated, but design flexibility is reduced once components are inserted into the circuit
Solution Approach 1:
The patent employs a universal microprocessor-based control system that can deliver high voltage to piezoelectric transducers through programmable power management. This single controller can adapt to different power requirements and transducer types, providing both high output capability and design flexibility without requiring separate dedicated circuits for each function.
Solution Approach 2:
The invention replaces traditional mechanical/power circuit approaches (bridge drivers, transformers, flyback circuits) with a microprocessor-based electronic control system. This substitution enables dynamic adjustment of power delivery and voltage generation through software control, eliminating the need for fixed, hardwired power conversion circuits and thereby improving design flexibility while maintaining high output capability.
3Device complexity
If fixed digital drive is used to drive piezoelectric transducers, then circuit simplicity is maintained, but adjustment of sound volume and tone is limited
Solution Approach 1:
The microprocessor-based control system provides self-service capability by automatically adjusting drive parameters based on programmed instructions. The controller can modify frequency, amplitude, and power delivery without requiring external manual adjustment, thereby maintaining circuit simplicity while enabling flexible sound volume and tone control through software programming.
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
Enables high drive power and flexible control over audio transducers, improving reliability and power capability by allowing programmable frequency and amplitude adjustments, and enhancing sound output quality.
Implementation Method 1
driving circuit that includes at least one energy storing inductor and one or more electronic switches adapted for energizing the energy-storing inductor and for transferring energy from the inductor to the audio transducer
Implementation Method 2
Piezoelectric transducers have been commonly used for the generation of audio tones in a number of applications
Data Source
AI summary
A controller, either a microprocessor or finite state machine, is used to generate a pulse train whose frequency and duty cycle can be varied to alter the frequency and amplitude of the output of a driven audio transducer. The ability to control both frequency and amplitude allows programmatic synthesis of many audio effects such as steady tones, warbles, beeps, sirens and chimes with no hardware or circuit changes. The transducer can be a piezoelectric bender or a speaker. The output of the controller controls a switch that builds current in an inductor when the switch is on. When the switch is turned off, the energy stored in the inductor is dumped into the audio transducer, either directly or through intermediate capacitor storage. This allows the generation of voltages across the transducer many times the supply voltage.