Capacitive Transducer Cell Gap Variation for Side Lobe Reduction
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Solution Overview
Problem
Capacitive transducers with uniformly spaced cells in square or rectangle shapes suffer from side lobes in ultrasound beams, leading to deteriorated image quality during both transmission and reception, and uneven transmission/receiving sensitivity across the element, which affects signal-to-noise ratio.
Innovation Solution
Designing a capacitive transducer with varying cell gaps between the end and middle portions, where the gap is larger at the end, reducing cell density and thus minimizing side lobes by ensuring uniform cell shape and radiation impedance across all cells, and incorporating dummy cells to maintain consistent acoustic crosstalk and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cells are arranged with uniform gaps in square or rectangle shape, then manufacturing is simplified, but side lobes occur in ultrasound beam causing image quality deterioration
Solution Approach 1:
The patent applies local quality by varying the gap between cells at different positions along the element. Specifically, the gap is made larger at the end portions and smaller at the middle portion, creating non-uniform local characteristics that suppress side lobes while maintaining overall manufacturing feasibility through systematic variation rather than complete complexity
Solution Approach 2:
The patent changes the geometric parameter of cell spacing along the length of the element. The gap distance is varied continuously or in steps from the middle portion to the end portions, transforming the uniform parameter into a graded parameter distribution that controls the ultrasound beam pattern and reduces side lobes
2Manufacturing precision
If cell shape varies between end and middle portions to reduce side lobes, then apodization is achieved, but transmission efficiency and receiving sensitivity become uneven across cells
Solution Approach 1:
The patent applies local quality selectively to the gap parameter while keeping cell shape uniform. This localized variation in spacing achieves apodization effects for side lobe suppression without the need to vary cell shapes, thereby maintaining uniform transmission efficiency and receiving sensitivity across all cells
Solution Approach 2:
The patent segments the element into different regions (middle portion and end portions) with different gap characteristics. This segmentation allows independent optimization of each region's gap size to control overall beam pattern while maintaining consistent cell performance characteristics throughout the element
3Ease of manufacture
If uniform cell gaps are used, then manufacturing is easier, but radiated sound pressure is uniform causing side lobe formation
Solution Approach 1:
The patent changes the gap parameter from uniform to graded variation along the element length. By increasing the gap at end portions and decreasing it at the middle portion, the radiation pattern is modified to suppress side lobes while the parameter change follows a systematic pattern that remains manufacturable
Solution Approach 2:
The patent converts the potentially harmful uniform radiation pattern that causes side lobes into a beneficial non-uniform pattern. By intentionally creating controlled non-uniformity in gap spacing, the side lobe problem is transformed into an opportunity to achieve desired beam shaping with improved image quality
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 reduces side lobes, improves signal-to-noise ratio, and ensures consistent transmission and receiving sensitivity, resulting in higher quality ultrasound images by minimizing interference from unnecessary frequency bands.
Implementation Method 1
Capacitive transducers using such technology have been studied as a substitute for piezoelectric elements. With such a capacitive transducer, an ultrasound wave can be transmitted and received using vibration of a vibrating membrane
Implementation Method 2
the radiated sound pressure is uniform in an end portion and a middle portion of the element. Therefore, a side lobe of an ultrasound beam easily occurs
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A side lobe in a capacitive transducer is reduced. Provided is a capacitive transducer including an element including a plurality of cells supported such that a vibrating membrane including one of a pair of electrodes formed with an gap inbetween is capable of vibration, wherein a distance between cells in an end portion of the element is greater than a distance between cells in a middle portion of the element.