Ultrasonic Phased Array with Non-Resonant Tx and Resonant Rx
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Solution Overview
Problem
Conventional ultrasonic transducer arrays face issues with distance resolution degradation due to overlapping reflected sonic waves from multiple obstacles and difficulty in precisely controlling phase dispersion near resonant frequencies, especially when using non-resonant transducers for reception, leading to reduced output voltage and noise separation challenges.
Innovation Solution
The ultrasonic transducer array employs a rigid support plate with through-holes and flexible resin film, combined with non-resonant transmission and resonant reception piezoelectric elements, to generate large reception voltage signals while improving phase control characteristics, using a phased array sensor configuration with delay circuits and adder circuits for precise obstacle detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If non-resonant transmission transducers are used to improve phase control characteristics, then phase control precision is improved, but reception output voltage decreases and noise separation becomes difficult
Solution Approach 1:
The patent applies different operational characteristics to transmission and reception transducers: transmission transducers operate in non-resonant mode for precise phase control, while reception transducers operate in resonant mode for high output voltage and noise rejection. This local differentiation resolves the contradiction by optimizing each function independently.
Solution Approach 2:
The patent inverts the conventional approach by using non-resonant transducers for transmission (unusual choice) to achieve precise phase control, and resonant transducers for reception (unusual choice) to achieve high sensitivity. This inversion of roles resolves the contradiction between phase control precision and reception output.
2Reliability
If transmission transducers are caused to resonate with sufficiently large output voltage, then reception sensitivity is improved, but distance resolution decreases due to overlapping reflected sonic waves
Solution Approach 1:
The patent differentiates the operational mode between transmission and reception transducers: transmission transducers operate non-resonantly to avoid damping vibrations that degrade distance resolution, while reception transducers operate resonantly to maximize reception sensitivity. This local optimization resolves the contradiction.
3Power
If driving voltage signal frequency is set near resonant frequency to achieve large output, then output voltage is improved, but phase control becomes difficult due to dispersion in resonance frequency
Solution Approach 1:
The patent changes the operating frequency parameter from near-resonant to non-resonant for transmission transducers, eliminating the phase dispersion problem while maintaining sufficient output through increased driving voltage. This parameter change resolves the contradiction between output voltage and phase control precision.
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 enables precise phase control of sonic waves, enhances reception voltage signals, and improves distance resolution by suppressing resonance frequency dispersion, allowing for effective obstacle detection and positioning using a phased array sensor.
Implementation Method 1
a plurality of piezoelectric elements whose number is same as a number of the plurality of through-holes, the piezoelectric element being fixed to the flexible resin film in such a way that a middle portion thereof overlaps, in a plan view, the corresponding through-hole
Implementation Method 2
the transmission transducer is of a non-resonant type that generates ultrasonic wave without performing resonant vibration in response to application of a driving voltage signal having a predetermined driving frequency
Implementation Method 3
one or a plurality of reception piezoelectric elements forming one or a plurality of reception transducers that generate reception voltage signals in response to reception of ultrasonic waves, wherein the reception transducer is of a resonant type that performs resonant vibration in response to receipt of ultrasonic wave having a frequency corresponding to the driving frequency
Data Source
AI summary
An ultrasonic transducer array of this invention includes a rigid support plate with a through-hole group including through-holes, a flexible resin film fixed to the support plate so as to cover the through-holes, and piezoelectric elements fixed to the flexible resin film so that middle portions overlap the corresponding through-holes and peripheral portions overlap the support plate, wherein the piezoelectric elements include transmission piezoelectric elements forming transmission transducers that generate ultrasonic waves in response to driving voltage signal having a predetermined driving frequency and one or plural reception piezoelectric elements forming one or plural reception transducers that generate reception voltage signals in response to ultrasonic waves, and wherein the transmission transducer is of a non-resonant type that generates ultrasonic wave without resonant vibration in response to the driving voltage signal and the reception transducer is of a resonant type that performs resonant vibration in response to ultrasonic wave having a frequency corresponding to the driving frequency.