Ultrasonic Sensor Piezoelectric Segmentation for Drive Characteristics
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Solution Overview
Problem
Ultrasonic wave sensors face degradation in drive characteristics due to increased total electrical capacitance when the number of ultrasonic wave transducers is increased to enhance sound pressure, leading to inefficient transmission.
Innovation Solution
The ultrasonic wave sensor employs a configuration with first and second piezoelectric elements, where the first elements are connected in parallel and driven to transmit sound waves, while the second elements, electrically insulated, resonate mechanically to enhance sound pressure without increasing total electrostatic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the number of ultrasonic wave transducers is increased to enhance sound pressure, then the sound pressure of transmitted ultrasonic wave is improved, but the drive characteristics are degraded due to increased total electrical capacitance
Solution Approach 1:
The patent divides the ultrasonic wave transducers into two distinct groups: first piezoelectric elements that are electrically connected in parallel to receive drive signals, and second piezoelectric elements that are electrically insulated and do not receive drive signals. This segmentation allows the system to achieve high sound pressure through mechanical coupling while avoiding the capacitance penalty of electrically connecting all elements in parallel.
Solution Approach 2:
The patent combines the functionality of multiple piezoelectric elements through mechanical coupling via the oscillating plate. The first piezoelectric elements generate ultrasonic waves that mechanically couple to the second piezoelectric elements through the shared oscillating plate structure, enabling the second elements to contribute to sound pressure without requiring electrical connection.
2Stress or pressure
If the number of first piezoelectric elements connected in parallel is increased to increase sound pressure, then the transmission sound pressure is improved, but the total electrostatic capacitance increases causing drive characteristic degradation
Solution Approach 1:
The patent segments the piezoelectric elements into first elements (electrically connected) and second elements (electrically insulated). This allows the system to utilize more piezoelectric elements for sound pressure generation while limiting the number of elements that contribute to total electrostatic capacitance, thereby avoiding drive characteristic degradation.
Solution Approach 2:
The oscillating plate serves as a mechanical intermediary that couples the first piezoelectric elements to the second piezoelectric elements. The drive signal applied to the first elements generates mechanical vibrations in the oscillating plate, which then mechanically drive the second elements to contribute to sound pressure without requiring direct electrical connection.
3Productivity
If more piezoelectric elements are electrically connected to receive drive signals, then the ultrasonic wave transmission capability is improved, but the drive circuit complexity and capacitance management become more difficult
Solution Approach 1:
The patent segments the piezoelectric elements into two functional groups with different electrical connection configurations. The first piezoelectric elements are connected in parallel to the drive circuit, while the second piezoelectric elements are electrically insulated. This segmentation simplifies the drive circuit by reducing the total capacitance that must be managed, while still achieving high transmission capability through mechanical coupling of all elements.
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 higher sound pressure transmission while maintaining drive characteristics, simplifying the drive circuit and reducing the need for increased capacitance, thus improving the overall performance of the ultrasonic wave sensor.
Implementation Method 1
the first piezoelectric element is expanded and contracted, the oscillator in which the first piezoelectric element is disposed oscillates, and thus the ultrasonic wave is transmitted from the drive transducer
Implementation Method 2
the oscillation of the oscillator of the drive transducer propagates to the oscillator in which the second piezoelectric element is disposed through the oscillating plate (mechanical crosstalk). Accordingly, the oscillator of the non-drive transducer resonates and the ultrasonic wave is transmitted also from the non-drive transducer
Data Source
AI summary
An ultrasonic wave sensor includes an oscillating plate including a plurality of oscillators, a wall portion provided on the oscillating plate and surrounding the oscillator, a first piezoelectric element provided in the predetermined number of oscillators among the plurality of oscillators, and a second piezoelectric element provided in the oscillator where the first piezoelectric element is not provided. An input and an output of a drive signal are possible to the first piezoelectric element, and the first piezoelectric element is connected to at least another first piezoelectric element in parallel. The second piezoelectric element is electrically insulated from the first piezoelectric element. The second piezoelectric element is disposed between the first piezoelectric elements adjacent in one direction.