Ultrasonic Sensor Attenuating Material Reduces False Detections
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Solution Overview
Problem
Ultrasonic sensors experience erroneous detections due to multiple reflections of ultrasonic waves between the fork arms of the housing, leading to interference and false detections, especially when emitting pulses with a predetermined repetition frequency.
Innovation Solution
The ultrasonic sensor incorporates a receiving opening surrounded by an attenuating material that absorbs or diffusely reflects ultrasonic waves, preventing unwanted multiple reflections and improving detection reliability by weakening the portion of waves that would cause false detections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ultrasonic waves are emitted with a predetermined repetition frequency, then the detection speed is improved, but multiple reflections cause interference and false detections
Solution Approach 1:
The patent applies acoustic absorption material in the housing corners to convert the harmful multiple reflections into beneficial damping effects. The reflected waves are absorbed by the material, preventing them from causing interference with subsequent pulses, thus enabling higher repetition frequencies without false detections.
Solution Approach 2:
The acoustic absorption material acts as an intermediary element between the ultrasonic waves and the housing structure. It mediates the interaction by absorbing the reflected energy, preventing the waves from traveling back and forth between fork arms and causing interference.
2Measurement precision
If the ultrasonic receiver is positioned to maximize reception, then the detection sensitivity is improved, but more waves are reflected back causing false detections
Solution Approach 1:
The patent converts the harmful reflected waves into beneficial absorbed energy by placing acoustic absorption material in the housing corners. This allows the receiver to be positioned for maximum sensitivity without the reflected waves causing false detections, as the absorption material damps the reflections.
3Ease of manufacture
If the housing structure is simplified, then the manufacturing cost is reduced, but multiple reflections occur causing false detections
Solution Approach 1:
The patent uses acoustic absorption material with porous structure in the housing corners. This material effectively absorbs reflected ultrasonic waves, preventing multiple reflections and false detections, while adding minimal complexity to the housing structure and maintaining ease of manufacture.
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
The attenuating material effectively reduces false detections by absorbing or diffusely scattering ultrasonic waves that are not guided through the receiving opening, enhancing the reliability of object detection in ultrasonic sensors.
Implementation Method 1
The attenuating material has an absorbing effect on ultrasonic waves, in particular through viscous friction in porous structures
Implementation Method 2
absorption by friction takes place in these pores
Implementation Method 3
The attenuating material has a diffusely scattering effect on ultrasonic waves
Data Source
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Figure 5a~6d
AI summary
The invention relates to an ultrasonic sensor (1) for detecting objects in a monitoring area, comprising an ultrasonic transmitter (3) emitting ultrasonic waves (2) and an ultrasonic receiver (4) receiving ultrasonic waves (2). A receiving aperture (11) is provided in a housing that accommodates the ultrasonic receiver (4). Ultrasonic waves (2) emitted by the transmitter and passing through the monitoring area are guided through this aperture to the ultrasonic receiver (4). The receiving aperture (11) is provided with an attenuating material that absorbs or diffusely reflects the ultrasonic waves (2).