Ultrasonic Sensor Sound Absorbing Portion for Reflection Noise
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Solution Overview
Problem
Ultrasonic sensors face noise issues due to multiple reflections of ultrasonic waves between the substrate and target objects, leading to inaccurate detection and positioning of objects, especially when the reflection surface is inclined or not directly aligned with the vibration film.
Innovation Solution
The ultrasonic device incorporates a substrate with openings and a sound absorbing portion on its end surface, featuring a curved surface to absorb ultrasonic waves reflected by the target object, thereby reducing multiple reflections and improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the substrate is provided with an opening and vibration film for ultrasonic transmission, then ultrasonic wave transmission capability is improved, but multiple reflections occur between the wall portion and target object causing noise
Solution Approach 1:
The invention converts the harmful multiple reflections into beneficial absorption by providing a sound absorbing portion on the end surface of the wall portion. This sound absorbing portion absorbs the ultrasonic waves that would otherwise reflect multiple times between the wall portion and target object, thereby eliminating noise while preserving the ultrasonic transmission capability through the opening.
Solution Approach 2:
The sound absorbing portion acts as an intermediary element between the ultrasonic wave and the wall portion's end surface. Instead of allowing direct reflection from the end surface, the sound absorbing portion intercepts and absorbs the ultrasonic waves, preventing them from causing multiple reflections and noise.
2Object-generated harmful factors
If the sound absorbing portion is provided on the end surface of the wall portion, then multiple reflections are suppressed, but the device structure becomes more complex
Solution Approach 1:
The sound absorbing portion is not provided across the entire substrate but only locally on the end surface of the wall portion where multiple reflections occur. This localized approach effectively suppresses multiple reflections while minimizing the increase in device complexity and maintaining simplicity in other areas of the device.
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 effectively suppresses multiple reflections, allowing for precise detection of objects, even when they are in unsuitable postures, and enhances the accuracy of ultrasonic sensors in applications like picking systems and image scanners.
Implementation Method 1
a sound absorbing portion provided over a second surface of the substrate... to absorb ultrasonic waves reflected by the target object, thereby reducing multiple reflections
Implementation Method 2
a piezoelectric element disposed at a position overlapping the opening on the vibration film... the vibration film is vibrated by driving the piezoelectric element to transmit an ultrasonic wave
Implementation Method 3
the vibration film is vibrated by driving the piezoelectric element to transmit an ultrasonic wave
Data Source
AI summary
An ultrasonic device includes a substrate having a first surface and a second surface having a front and back relationship with the first surface, and provided with an opening penetrating the second surface from the first surface; a vibration film provided over the first surface of the substrate so as to close the opening; a vibration element provided at a position overlapping the opening in the vibration film; and a sound absorbing portion provided over the second surface of the substrate.