Ultrasound Transducer Bias Control for c-MUT Protection
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Solution Overview
Problem
Capacitive micro-machined ultrasonic transducers (c-MUT) in ultrasound diagnostic apparatuses require both a driving signal and a bias voltage for transmission and reception, but excessive bias voltage can cause damage, leading to short circuits and overcurrent issues, necessitating overvoltage detection and protection circuits to prevent damage.
Innovation Solution
An ultrasound diagnostic apparatus with a control portion that manages the output timings of bias voltage and transmission signals, allowing for safe operation by stopping bias voltage application when necessary, and displaying connection states between piezoelectric and capacitive transducers, enabling controlled output and preventing damage to c-MUT elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bias voltage is applied to a c-MUT element to enable transmission and reception, then the sensitivity can be controlled, but excessive bias voltage causes short circuit and overcurrent leading to damage
Solution Approach 1:
The control portion applies the bias voltage to the c-MUT element before applying the transmission signal. This preliminary action ensures that the c-MUT element is properly biased and ready to handle the transmission signal, preventing damage from improper voltage application sequences
Solution Approach 2:
The control portion stops applying the bias voltage after the transmission signal has been applied. This periodic action (apply bias voltage, then stop) prevents continuous excessive voltage application that could cause short circuits and overcurrent damage to the c-MUT element
2Reliability
If the bias voltage is stopped before the transmission signal, then the c-MUT element is protected from overcurrent, but the transmission signal cannot be properly received
Solution Approach 1:
The control portion applies the bias voltage before the transmission signal to ensure the c-MUT element is properly prepared for receiving the transmission signal, maintaining reception quality while preventing damage through proper sequencing
3Reliability
If overvoltage detection means is provided to prevent excessive bias voltage, then damage is prevented, but the device complexity increases
Solution Approach 1:
The control portion monitors the bias voltage level and automatically adjusts its application accordingly. This feedback mechanism prevents excessive voltage application and potential damage without requiring complex external overvoltage detection circuits, simplifying the overall device architecture
Solution Approach 2:
The control portion inherently includes the protection function by managing the bias voltage application timing itself. The control portion stops applying bias voltage after transmission signals are sent, providing self-protection against overcurrent damage without requiring separate complex protection circuits
4Adaptability or versatility
If the c-MUT element is used with bias voltage control, then sensitivity can be adjusted, but the risk of short circuit and overcurrent damage increases
Solution Approach 1:
The control portion applies the bias voltage periodically - before transmission signals and then stops after transmission signals are sent. This periodic application allows sensitivity adjustment during transmission while preventing continuous voltage application that could cause short circuits and overcurrent damage
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
Prevents damage to c-MUT elements by controlling bias voltage and transmission signal timing, ensuring safe operation and maintaining transducer sensitivity, while allowing connection with both piezoelectric and capacitive transducers.
Implementation Method 1
applying a driving signal to one of the electrodes of the c-MUT element while applying a bias voltage between the two electrodes to thereby cause a film (a membrane constituting the second electrode) at an upper part of the cavity to vibrate and transmit ultrasound
Implementation Method 2
a piezoelectric ultrasound transducer that does not require bias voltage control can be connected to the ultrasound diagnostic apparatus
Data Source
AI summary
An ultrasound diagnostic apparatus is connectable with an ultrasound probe having a c-MUT element or a piezoelectric ultrasound transducer, and includes a DC bias output portion, a transmission signal output portion, an operation portion, a control portion, and a display portion. The control portion controls the DC bias output portion and the transmission signal output portion so as to output an ultrasound transmission signal after applying the bias voltage when an instruction signal instructing the start of transmission is inputted from the operation portion, and so as to stop application of the bias voltage after stopping output of the ultrasound transmission signal when an instruction signal that instructs stopping of transmission is inputted from the operation portion. The control portion causes a connection state showing which one of the c-MUT element and the capacitive micro-machined ultrasonic transducer is connected to be displayed on the display portion.