Shield Electrode Section for Ultrasonic Element Voltage Stability
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Solution Overview
Problem
The stability of electrostatic capacitance ultrasound transducers is compromised due to potential leaks from defects in the insulating film covering the lower electrode section or wiring, leading to unstable characteristics in ultrasound endoscopes.
Innovation Solution
Incorporating a shield electrode section at ground potential, formed using a sacrificial layer, which prevents voltage leakage even if the insulating film is broken, and using a coaxial cable bundle to connect the electrodes, ensuring stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating film is used to cover the lower electrode section or lower wiring section, then electrical insulation is provided, but the insulating film may be broken due to dust, defects or other factors causing potential leakage and unstable characteristics
Solution Approach 1:
The patent divides the electrode structure into multiple independent cells (first capacitor cell, second capacitor cell, etc.), where each cell has its own lower electrode section, upper electrode section, and insulating film. This segmentation isolates potential breakdown events to individual cells, preventing system-wide failure and maintaining overall stability even when one cell's insulating film breaks.
Solution Approach 2:
The patent applies a protective coating layer over the insulating film before potential breakdown can occur. This cushioning layer serves as a preventive measure against dust, defects, and other harmful factors that could cause insulating film breakdown, thereby maintaining reliability without requiring thicker or more fragile insulating materials.
2Power
If multiple capacitor cells are arranged in an array to form an ultrasound element, then ultrasound transmission and reception capability is improved, but the complexity of wiring and electrode connections increases
Solution Approach 1:
The patent merges the wiring functions by connecting lower electrode sections of multiple capacitor cells to a common lower electrode terminal and upper electrode sections to a common upper electrode terminal. This combining approach maintains the independent operation of each capacitor cell for ultrasound transmission while significantly reducing wiring complexity and simplifying the overall electrode structure.
3Reliability
If a shield electrode section is added at ground potential to prevent voltage leakage, then stability is improved, but the device complexity increases
Solution Approach 1:
The patent integrates the shield electrode section into the existing electrode structure of each capacitor cell, where it serves multiple functions: providing ground reference for voltage stability, acting as a barrier against external electromagnetic interference, and maintaining mechanical structural integrity. This multi-functionality approach adds stability without proportionally increasing device complexity.
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 shield electrode section maintains stable voltage within the ultrasound cell, enhancing the stability and reception sensitivity of the ultrasound element and endoscope, while simplifying the manufacturing process.
Implementation Method 1
a shield electrode section at ground potential, formed using a sacrificial layer, which prevents voltage leakage even if the insulating film is broken
Implementation Method 2
The US cell vibrates a membrane (a vibration portion) including the upper electrode section by an electrostatic force by applying a voltage to between the lower electrode section and the upper electrode section, and generates ultrasound
Implementation Method 3
When ultrasound enters from an outside, a space between both the electrodes changes, and therefore, the ultrasound is converted into an electric signal from a change of an electrostatic capacitance
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A US element 20 includes a silicon substrate 11, wherein a lower electrode layer 12 that has a plurality of lower electrode sections 12A, and a plurality of lower wiring sections 12B, and is connected to a lower electrode terminal 52 to which a drive signal and a bias signal are applied, a lower insulating layer 13, an upper insulating layer 15 in which a plurality of cavities 14 are formed, an upper electrode layer 16 that has a plurality of upper electrode sections 16A and a plurality of upper wiring sections 16B, and is connected to an upper electrode terminal 51 at a ground potential for detecting a capacitance signal, and a protection layer 17 are sequentially stacked on the silicon substrate 11, and the US element 20 further includes a shield electrode section 71 that is formed at least at an upper side of the lower wiring sections 12B, and is connected to a shield electrode terminal 53 at a ground potential.