Ultrasonic Transducer Waveguide Electrodes for Crosstalk Reduction
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Solution Overview
Problem
Crosstalk between ultrasonic waves reflected from different positions of a detected object affects the detection accuracy of ultrasonic transducers, particularly in applications like fingerprint recognition.
Innovation Solution
The ultrasonic transducer is designed with a first electrode layer comprising spaced first electrode blocks, each with a thickness greater than a wavelength threshold, and a second electrode layer with spaced second electrode blocks, where the orthographic projection of each first electrode block overlaps at least one second electrode block, forming waveguide structures that limit ultrasonic wave propagation paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous electrode layers are used in ultrasonic transducers, then the device structure is simple and easy to manufacture, but crosstalk between ultrasonic waves from different positions increases, reducing detection accuracy
Solution Approach 1:
The continuous electrode layers are divided into discrete electrode blocks arranged in arrays. The first electrode layer includes multiple first electrode blocks, and the second electrode layer includes multiple second electrode blocks, where each first electrode block corresponds to one or more second electrode blocks. This segmentation creates independent ultrasonic transmission paths, reducing crosstalk between adjacent elements while maintaining structural organization through the block array configuration.
2Length of moving object
If electrode blocks with small thickness are used, then the device thickness is reduced, but the waveguide effect is insufficient, leading to increased crosstalk between ultrasonic waves
Solution Approach 1:
The thickness of electrode blocks is optimized to be greater than one-quarter of the ultrasonic wavelength (t > λ/4), creating an effective acoustic impedance mismatch that generates strong reflections at the interfaces. This parameter optimization ensures that each electrode block acts as an effective acoustic mirror, reflecting ultrasonic waves back along their original path and reducing crosstalk, while the overall transducer thickness is controlled by optimizing this critical parameter.
3Measurement precision
If the thickness of electrode blocks is increased to reduce crosstalk, then the waveguide effect is improved, but the overall transducer thickness increases
Solution Approach 1:
The electrode block thickness is optimized to be greater than one-quarter of the ultrasonic wavelength (t > λ/4), which is the minimum thickness required to achieve effective acoustic impedance mismatch and strong wave reflection. By setting the thickness to this critical value rather than increasing it further, the transducer achieves effective crosstalk reduction while minimizing the overall thickness increase, as thicker blocks would provide diminishing returns while proportionally increasing device thickness.
4Measurement precision
If discrete electrode blocks are used instead of continuous layers, then crosstalk between ultrasonic waves is reduced, but manufacturing complexity increases
Solution Approach 1:
The electrode layers are segmented into discrete blocks that can be fabricated using standard photolithography and sputtering or evaporation techniques. The block patterns are defined by photomask design and etching processes, which are conventional in thin-film deposition. This segmentation approach maintains compatibility with existing manufacturing workflows while achieving the desired crosstalk reduction through the spatial separation of electrode blocks.
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 effectively reduces crosstalk between ultrasonic waves, ensuring high detection accuracy and improving the signal-to-noise ratio of electrical signals, thereby enhancing the overall performance of the ultrasonic transducer.
Implementation Method 1
An ultrasonic transducer is a device that can implement mutual conversion between acoustic energy and electric energy based on piezoelectric effect
Implementation Method 2
the ultrasonic transducer can convert the ultrasonic waves of different strength into electrical signals of different strength
Data Source
AI summary
An ultrasonic transducer, a fingerprint recognition module, and an electronic device are provided, and belong to the field of ultrasonic detection technologies. The ultrasonic transducer includes a first electrode layer (01), a piezoelectric material layer (02), and a second electrode layer (03) that are sequentially stacked. The first electrode layer (01) includes a plurality of spaced first electrode blocks (011), the second electrode layer (03) includes a plurality of spaced second electrode blocks (031), and orthographic projection of each first electrode block (011) on the second electrode layer (03) overlaps at least one second electrode block (031). The first electrode layer (01) is disposed in a discretized manner, and a thickness of each first electrode block (011) is greater than a thickness threshold, so that a plurality of waveguide structures that can limit propagation paths of ultrasonic waves can be formed at the first electrode layer (01).