Ultrasonic Sensor Reverberation Suppression Circuit
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Solution Overview
Problem
Existing ultrasonic sensors face complexity in circuit configuration due to the need for separate detection and suppression of reverberant vibrations, which affects sensitivity and accuracy in object detection.
Innovation Solution
An ultrasonic sensor design featuring a flat-plate-shaped piezoelectric element with a common electrode and separate transmission and reception electrodes, utilizing a semiconductor element to switch the electrical path between conductive and non-conductive states, and a phase adjuster to suppress reverberant vibrations by feeding back the reverberation signal with adjusted phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate detection part and transmission/reception part are provided to suppress reverberant vibrations, then reverberant vibration suppression is achieved, but the circuit configuration becomes more complex
Solution Approach 1:
The patent combines the transmission electrode and reception electrode into a single piezoelectric element structure. The reception electrode detects both reflected waves and reverberant vibrations, and the control circuit processes both signals to suppress reverberation while detecting objects, eliminating the need for separate detection parts
Solution Approach 2:
The reception electrode serves multiple functions: it detects reflected waves from objects and simultaneously detects reverberant vibrations generated during transmission. The control circuit also performs multiple functions by generating both the transmission signal and the reverberation suppression signal based on the reception signal
2Reliability
If the electrical path is kept conductive during transmission, then reverberation signal feedback is enabled, but transmission and reception signals interfere with each other
Solution Approach 1:
The semiconductor element switches the electrical path between conductive and non-conductive states in periodic cycles. During transmission, the path is non-conductive to prevent interference; after transmission stops, the path becomes conductive to enable reverberation signal feedback for suppression
Solution Approach 2:
The control circuit generates the reverberation suppression signal in advance by processing the reception signal during the conductive state, and applies this pre-generated signal when the electrical path is in the non-conductive state to suppress reverberations before they interfere with reception
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 simplifies the circuit while effectively suppressing reverberant vibrations, enhancing detection accuracy and sensitivity, allowing for closer object detection without waiting for natural vibration subsidence.
Implementation Method 1
An ultrasonic sensor causes a piezoelectric element to vibrate by applying an alternating-current voltage to a piezoelectric element
Implementation Method 2
The ultrasonic sensor detects an object on the basis of reception of an ultrasonic wave reflected by the object
Data Source
Figure 1
Figure 2(A)~2(C)
Figure 3
AI summary
Provided is an ultrasonic sensor that can suppress a reverberant vibration by using a simpler circuit configuration than was previously possible. An ultrasonic sensor (100) includes: a flat-plate-shaped piezoelectric body (50), which includes a transmission region (50A) for an ultrasonic wave and a reception region (50B) for a reflected wave of the ultrasonic wave; a common electrode (30) that is provided in the transmission region (50A) and the reception region (50B); a transmission electrode (10) that is provided in the transmission region (50A); a reception electrode (20) that is provided in the reception region (50B); a semiconductor element (107) that is electrically connected to the transmission electrode (10) and the reception electrode (20); and a semiconductor element (107) that is electrically connected to the transmission electrode (10) and the reception electrode (20) and switches a path (109) between a conductive state and a non-conductive state. The semiconductor element (107) puts the path (109) into the conductive state after application of the alternating-current voltage is stopped, and as a result, a reverberation signal, which is output from the reception region (50B) in accordance with a reverberant vibration of the ultrasonic wave, is fed back to the transmission electrode (10).