Ultrasonic Transducer Control Using Critically Coupled LC Resonance
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Solution Overview
Problem
Existing ultrasonic transducer systems are limited by a maximum transducer oscillation voltage amplitude of twice the operating voltage, which restricts the range and efficiency of ultrasonic sensors in autonomous driving applications, necessitating a cost-effective solution without transformers.
Innovation Solution
A fourth-order oscillating system is implemented using a series inductor and capacitor in conjunction with a parallel capacitor, critically coupling the resonant circuits to achieve an AC voltage amplitude greater than twice the operating voltage, eliminating the need for transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If transformers are eliminated to reduce costs, then device complexity and cost are reduced, but the maximum transducer oscillation voltage amplitude is limited to twice the operating voltage
Solution Approach 1:
The patent changes the electrical parameters of the driving circuit by introducing a resonant circuit with specific inductance and capacitance values. The resonant frequency is tuned to match the transducer's natural frequency, enabling voltage amplification through resonance. This allows the circuit to achieve higher voltage amplitudes without transformers by exploiting the resonant buildup of energy in the LC circuit.
Solution Approach 2:
The patent applies the principle of mechanical vibration by using electrical resonance in the LC circuit. The resonant oscillations at the transducer's natural frequency create constructive interference, amplifying the voltage amplitude across the transducer. This resonance-based amplification replaces the function of transformers in voltage step-up applications.
2Device complexity
If the transducer oscillation voltage amplitude is limited to twice the operating voltage, then the circuit design is simplified, but the detection range and efficiency of ultrasonic sensors are reduced
Solution Approach 1:
The patent modifies the circuit parameters by adding a resonant LC circuit with carefully selected inductance and capacitance values. The resonant frequency is matched to the transducer's operating frequency, creating a condition where energy accumulates constructively. This parameter change enables the system to achieve higher voltage amplitudes and extended detection ranges while maintaining relatively simple circuit topology.
Solution Approach 2:
The patent utilizes electrical resonance analogous to mechanical vibration principles. By driving the transducer at its resonant frequency through the LC circuit, the system achieves maximum energy transfer and voltage amplification. This resonance effect extends the effective detection range of the ultrasonic sensor without requiring complex multi-stage amplifier circuits.
3Strength
If charge pump methods are used to increase voltage beyond operating voltage, then transducer oscillation voltage amplitude is increased, but device complexity and cost increase
Solution Approach 1:
The patent extracts the voltage amplification function from complex active components like charge pumps and implements it through a passive resonant LC circuit. By removing the need for active voltage multiplication stages and replacing them with a resonant energy storage system, the design achieves high voltage amplitudes with significantly reduced component count and complexity.
Solution Approach 2:
The patent replaces active electronic voltage multiplication mechanisms (charge pumps) with a passive resonant electrical system. The LC resonant circuit naturally amplifies voltage through energy oscillation between the inductor and capacitor, substituting complex active voltage control circuits with a simpler passive resonant system that achieves the same voltage amplification effect.
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 approach enhances the transducer's range and efficiency by amplifying the vibration levels beyond the conventional limit, improving the performance of ultrasonic sensors without increasing costs.
Implementation Method 1
a fourth-order oscillating system is implemented using a series inductor and capacitor in conjunction with a parallel capacitor, critically coupling the resonant circuits to achieve an AC voltage amplitude greater than twice the operating voltage
Implementation Method 2
transformers were used to drive the piezoelectric oscillators of ultrasonic transducers
Data Source
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AI summary
The device for operating an ultrasonic transducer (TR) is equipped with a drive circuit having a first output terminal (GND) and a second output terminal (DRV). Furthermore, the device includes a driver output resistor, which is effectively connected between a positive terminal (TR+) for the transducer (TR) and the second output terminal (DRV) of the drive circuit. A negative terminal (TR-) for the transducer (TR) is connected to the first output terminal (GND) of the drive circuit. A transducer capacitance (CTR) is connected between the positive terminal (TR+) and the negative terminal (TR-) for the transducer (TR). A driver output inductance (LDRV) is effectively connected in series with the driver output resistor (RDRV) between the positive terminal (TR+) of the transducer (TR) and the second output terminal (DRV) of the drive circuit.The driver output inductance (LDRV) is dimensioned such that a first series resonant circuit consisting of the series inductance (LTRs) and series capacitance (CTRs) of the equivalent circuit of the transducer (TR) and a second series resonant circuit consisting of the driver output inductance (LDRV) and the parallel circuit consisting of the transducer capacitance (CTR) and parallel capacitance (CTRp) of the equivalent circuit of the transducer (TR) are critically coupled.