Ultrasonic Sensor Opening Section Asymmetry for Crosstalk Reduction
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Solution Overview
Problem
Conventional ultrasonic sensors suffer from crosstalk and noise due to ultrasound reflections between the end portions of rectangularly shaped opening sections, which affects the accuracy of distance measurements.
Innovation Solution
The ultrasonic sensor features a unique opening section design with inclined sides and beam sections on the element substrate, allowing for a reduction in the distance between adjacent opening sections and minimizing crosstalk by directing ultrasound reflections away from active sections, thereby improving measurement accuracy and reducing the size of the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rectangular opening section is used in the ultrasonic sensor, then the structure is simple and easy to manufacture, but ultrasound reflections between end portions cause crosstalk and reduce measurement accuracy
Solution Approach 1:
The opening section is designed with a trapezoidal shape where the width in the X-direction varies along the Y-direction, creating asymmetric end portions. This asymmetric geometry prevents parallel reflection paths between opposite ends, thereby eliminating crosstalk while maintaining manufacturing feasibility through standard semiconductor fabrication processes.
Solution Approach 2:
The end portions of the opening section are designed with inclined surfaces rather than sharp rectangular corners. These inclined surfaces redirect reflected ultrasound away from active sections, reducing crosstalk. The curved/inclined geometry smoothly redirects acoustic waves without creating strong specular reflections that would cause measurement errors.
2Volume of moving object
If the distance between adjacent opening sections is reduced to miniaturize the sensor, then the device size decreases, but crosstalk between adjacent sections increases
Solution Approach 1:
By making the opening sections trapezoidal with non-parallel end portions, the reflection paths of ultrasound from adjacent sections are diverged rather than parallel. This allows adjacent sections to be placed closer together without their reflected ultrasound interfering with each other's active sections, enabling miniaturization while controlling crosstalk.
Solution Approach 2:
The inclined surfaces at the end portions act as acoustic deflectors that redirect reflected ultrasound away from adjacent active sections. This geometric feature reduces inter-section crosstalk, allowing tighter packing of opening sections to reduce overall sensor size while maintaining signal quality.
3Measurement precision
If ultrasound frequency is increased to improve measurement precision, then measurement accuracy improves, but the active sections become more susceptible to reflected ultrasound causing crosstalk
Solution Approach 1:
The inclined surfaces at the end portions of the opening section redirect reflected ultrasound at angles that prevent it from re-entering the active sections. This geometric configuration reduces the impact of reflected ultrasound on high-frequency active sections, allowing higher operating frequencies to be used for improved measurement accuracy without excessive crosstalk.
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 design enhances the accuracy of distance measurements by reducing crosstalk and noise, enabling a more precise control over ultrasound transmission and reception, and allows for a smaller, more reliable ultrasonic sensor configuration.
Implementation Method 1
a piezoelectric element is disposed on the vibrating plate in a position corresponding to the opening section
Implementation Method 2
the active sections are capable of transmitting and receiving ultrasound having a desired frequency
Implementation Method 3
a part of ultrasound output into the opening section is reflected between both end portions of the rectangle and is input to the active sections again
Data Source
AI summary
An ultrasonic sensor includes an element substrate having a first and a second surface at an opposite side of the first surface, including an opening section piercing through the element substrate in a Z direction from the first to second surface, a vibrating plate on the first surface of the element substrate to close the opening section, a plurality of vibration regions extending along an X direction orthogonal to the Z direction on the vibration plate in positions overlapping the opening section, and a plurality of piezoelectric elements to correspond to the plurality of vibration regions of the vibration plate. The opening section includes, on the first surface, a first and second side parallel to the X direction and a third and fourth side coupling end portions in the X direction of the first and second sides at an acute or obtuse angle to the first and the second side.