JP2008136725A - Ultrasonic probe and ultrasonic diagnostic system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic probe and an ultrasonic diagnostic system that prevents any excessive output of ultrasonic waves to a subject to improve the subject's safety. <P>SOLUTION: A protective circuit 13 is composed of a switch device 31, resistors 32 and 33, an electric voltage detection circuit 34, a coupling circuit 35, etc. If the ultrasonic diagnostic system 1 is normal and its DC bias voltage is below the threshold value, the switch device 31 is closed (ON). If the system 1 is abnormal and its DC bias voltage has reached the threshold value, a voltage detection circuit 34 outputs an OFF signal through a coupling circuit 35 to release a switch device 31 (OFF). Upon the release of the switch device 31, an electric connection between a bias circuit 6 and an ultrasonic probe 2 is shut off. This will prevent any excessive output of ultrasonic waves to a subject when an abnormality has occurred and improve the subject's safety. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasound probe and an ultrasound diagnostic apparatus that capture a diagnostic image.

  Conventionally, a capacitive micro-machined ultrasonic transducer (cMUT) has been manufactured using a semiconductor film forming technique. The cMUT is a minute diaphragm-like device, and includes an electrode that converts acoustic vibration of an ultrasonic signal into a modulation type capacitance. The cMUT has a sacrificial layer between electrodes, a DC bias and an AC pulse are applied between the electrodes, a capacitive charge is modulated to generate an electric field, and an ultrasonic wave is generated by vibrating the vibrating membrane.

  In addition, a capacitive micromachine ultrasonic transducer that monitors the capacitance of the cMUT with a capacitance regulator and adjusts the bias charge has been proposed. The capacitance regulator measures the capacitance of the cMUT by measuring a minute AC voltage caused by charging or discharging at the diaphragm electrode. Thereby, the generation and maintenance of the bias charge is performed (for example, refer to [Patent Document 1]).

  When the magnitude of the DC bias applied between the electrodes of the cMUT exceeds a predetermined range, the elastic force of the vibrating membrane cannot support the Coulomb force caused by the DC bias, causing an imbalance, and a drum-like shape sandwiched between the electrodes. The sacrificial layer becomes crushed. This state is referred to as a collapse state, and the applied voltage value of the DC bias at this time is referred to as a collapse voltage (Vcol). An insulating film is provided between the electrodes of the cMUT, and the cMUT itself is not damaged even when the Collapse state is reached.

Japanese translation of PCT publication No. 2004-50312

However, in the Collapse state, the ultrasonic wave transmission output increases, and there is a risk of exceeding the standard range of the ultrasonic output for the subject. In the Collapse state, the ultrasonic transmission output rises by about 10 dB with respect to the rated ultrasonic transmission output. Further, when the Collapse state continues, the Collapse voltage is lowered with time due to the influence of the leakage current, and the Collapse state is likely to occur.
In the above-mentioned [Patent Document 1], there is a DC bias control circuit, but there is no protection circuit, and there is a problem that the subject may be in danger in the Collapse state.

  The present invention has been made in view of the above problems, and an ultrasonic probe and an ultrasonic wave capable of preventing excessive output of ultrasonic waves to the subject and improving the safety of the subject. An object is to provide a diagnostic apparatus.

  In order to achieve the above-described object, the first invention provides a vibrator having a plurality of vibration elements that include a pair of electrodes and whose ultrasonic transmission / reception sensitivity changes according to a bias voltage applied between the electrodes by a bias power source. An ultrasonic probe comprising: a switch element provided between the electrode and the bias power source; and a bias voltage provided between the electrodes and applied between the electrodes, and the detected bias An ultrasonic probe comprising: a voltage detection circuit that outputs a drive signal to the switch element in accordance with the magnitude of the voltage.

An ultrasonic probe according to a first invention includes a switch element and a voltage detection circuit. The switch element is provided between an electrode included in the vibration element and a bias power source. The voltage detection circuit is provided between a pair of electrodes provided in the vibration element. The voltage detection circuit detects a bias voltage applied between the electrodes and outputs a drive signal to the switch element according to the detected magnitude of the bias voltage.
When the voltage detection circuit detects a predetermined threshold voltage, the voltage detection circuit outputs an OFF signal to the switch element to open the switch element (OFF).

  As a result, when the abnormality of the DC bias applied between the electrodes of the vibration element is detected, the electrical connection between the bias circuit and the ultrasonic probe can be interrupted by opening the switch element (OFF). it can. When an abnormality occurs, it is possible to improve the safety of the subject by preventing excessive output of ultrasonic waves to the subject.

  A coupling circuit may be provided between the voltage detection circuit and the switch element. Thereby, the high voltage circuit side and the low voltage circuit side can be separated and the low voltage circuit side can be protected.

In addition, an external control device that outputs a drive signal to the switch element independently of the voltage detection circuit, and an addition process that adds the drive signal from the external control device and the drive signal from the voltage detection circuit to output to the switch element And a vessel may be provided.
Thereby, the switch element can be opened (OFF) at an arbitrary timing, and the power consumption can be reduced.

  According to a second aspect of the present invention, there is provided an ultrasonic probe that transmits / receives an ultrasonic wave to / from a subject, an image processing unit that forms an ultrasonic image based on an ultrasonic reception signal output from the ultrasonic probe, An ultrasonic diagnostic apparatus comprising: a display unit that displays an ultrasonic image; wherein the ultrasonic probe is the ultrasonic probe according to the first aspect of the invention.

The second invention is an invention relating to an ultrasonic diagnostic apparatus comprising the ultrasonic probe of the first invention.
Further, when the switch element is in an open state (OFF), a warning may be displayed on the display unit. As a result, the examiner can confirm the occurrence of the abnormality by the screen display of the display unit and perform the recovery work.

  ADVANTAGE OF THE INVENTION According to this invention, the ultrasonic probe and ultrasonic diagnostic apparatus which can prevent the excessive output of the ultrasonic wave with respect to a test subject and can improve the safety | security of a test subject can be provided.

  Exemplary embodiments of an ultrasonic probe and an ultrasonic diagnostic apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. In the following description and the accompanying drawings, the same reference numerals are given to components having substantially the same functional configuration, and redundant description is omitted.

(1. Configuration of ultrasonic diagnostic equipment)
First, the configuration of the ultrasonic diagnostic apparatus 1 will be described with reference to FIG.
FIG. 1 is a configuration diagram of the ultrasonic diagnostic apparatus 1.
The ultrasonic diagnostic apparatus 1 is configured by connecting an ultrasonic probe 2 and a main body 4 via a cable 14. The main body 4 includes a transmission circuit 5, a bias circuit 6, a reception circuit 7, an image processing unit 8, a display unit 9, a transmission / reception separation circuit 10, a control unit 11, an operation unit 12, and a protection circuit 13.

  The ultrasonic probe 2 is a device that transmits and receives ultrasonic waves to and from a subject by contacting the subject. An ultrasonic wave is emitted from the ultrasonic probe 2 to the subject, and a reflected echo signal generated from the subject is received by the ultrasonic probe 2. The ultrasonic probe 2 includes a vibrator composed of a plurality of vibration elements 3. The vibration element 3 is, for example, a cMUT cell.

The transmission circuit 5 and the bias circuit 6 are circuits that supply a drive signal and a DC bias to the ultrasound probe 2.
The receiving circuit 7 is a circuit that receives a reflected echo signal output from the ultrasonic probe 2. The receiving circuit 7 further performs processing such as analog-digital conversion on the received reflected echo signal.
The image processing unit 8 is a device that configures a diagnostic image (for example, a tomographic image or a blood flow image) based on the reflected echo signal subjected to phasing addition.
The display unit 9 is a display device that displays a diagnostic image subjected to image processing.

The transmission / reception separation circuit 10 is a circuit that separates the ultrasonic transmission signal and the ultrasonic reception signal.
The control unit 11 is a device that controls each component described above.
The operation unit 12 is a device that gives an instruction to the control unit 11. The operation unit 12 is an input device such as a trackball, a keyboard, or a mouse.

  The protection circuit 13 is a circuit for protecting the subject so that an excessive DC bias is not applied to the ultrasound probe 2. Although FIG. 1 shows that the protection circuit 13 is provided on the main body 4 side, a part of the protection circuit 13 may be provided on the ultrasonic probe 2 side. Details of the protection circuit 13 will be described later.

(2. First Embodiment)
Next, the first embodiment will be described with reference to FIGS. 2 and 3.

(2-1. Configuration of Protection Circuit 13)
FIG. 2 is a configuration diagram of the protection circuit 13 of the ultrasonic diagnostic apparatus 1 according to the first embodiment.
The protection circuit 13 is provided between the transmission / reception separation circuit 10 and the vibration element 3 of the ultrasonic probe 2. An equivalent circuit of the vibration element 3 is represented by a model in which a capacitor 27 (Ccell) and a resistor 28 (Rcell) are connected in parallel. The protection circuit 13 includes a switch element 31, a resistor 32, a resistor 33, a voltage detection circuit 34, a coupling circuit 35, and the like.

  In FIG. 2, the switch element 31 is provided on the main body 4 side, and the resistor 32 and the resistor 33, the voltage detection circuit 34 and the coupling circuit 35 are provided on the ultrasonic probe 2 side. The transmission circuit 5 includes a capacitor 22 and an AC pulse signal source 23. The reception circuit 7 includes a reception amplifier 24 (preamplifier). The bias circuit 6 includes a DC power source 21 that is a bias power source.

  The switch element 31 is arranged in series between the DC power source 21 of the bias circuit 6 and the electrode 25 or the electrode 26 of the vibration element 3. Usually, the switch element 31 is in a closed state (ON). The switch element 31 is, for example, a semiconductor switch made of an FET (field effect transistor) or the like with a small leakage current, a micro relay or a mechanical relay such as an electrostatic relay or an electromagnetic relay that can be easily controlled.

The resistor 32 and the resistor 33 are arranged in parallel with the electrode 25 and the electrode 26. The resistor 32 is desirably a high resistance. The resistance value of the resistor 32 is, for example, several MΩ. Thereby, inflow of a large current at the time of abnormality occurrence can be prevented. Further, the high input impedance property of the reception amplifier 24 of the reception circuit 7 can be ensured.
The voltage detection circuit 34 is a circuit that outputs a predetermined signal according to the detected voltage. The voltage detection circuit 34 includes an IC (integrated circuit), a transistor, a diode, a resistor, and the like. The voltage detection circuit 34 can perform voltage detection by using a comparator such as a comparator. The input side of the voltage detection circuit 34 is connected to a connection point between the resistor 32 and the resistor 33.
The coupling circuit 35 is connected to the output side of the voltage detection circuit 34. The coupling circuit 35 is, for example, a photocoupler. The coupling circuit 35 separates the high voltage circuit side and the low voltage circuit side to protect the low voltage circuit side.

(2-2. Operation of protection circuit 13)
FIG. 3 is a characteristic diagram showing the relationship between the DC bias voltage and the ultrasonic output.
The graph 42 shows the ultrasonic output (P) when the DC bias voltage (Vdc) is less than the threshold voltage 41 (Vth). Within the range of the graph 42, the ultrasonic output can be controlled by controlling the DC bias voltage (Vdc).
The graph 43 shows the ultrasonic output (P) when the DC bias voltage (Vdc) is equal to or higher than the threshold voltage 41 (Vth). Outside the range of the graph 42, since the ultrasonic output changes rapidly, it is difficult to control the ultrasonic output by controlling the DC bias voltage (Vdc).

When the ultrasonic diagnostic apparatus 1 is in a normal state and the DC bias voltage (Vdc) is less than the threshold voltage 41 (Vth), the switch element 2 is in a closed state (ON).
On the other hand, when an abnormality occurs in the ultrasonic diagnostic apparatus 1 and the DC bias voltage (Vdc) reaches the threshold voltage 41 (Vth), this threshold voltage arrival is detected by the voltage detection circuit 34. The voltage detection circuit 34 outputs an OFF signal to the switch element 31 via the coupling circuit 35, and makes the switch element 31 open (OFF).

(2-3.)
As described above, in the first embodiment, when detecting an abnormality in the DC bias applied between the electrodes of the vibration element 3, the ultrasonic diagnostic apparatus biases the switch element by opening it (OFF). The electrical connection between the circuit and the ultrasonic probe 2 is cut off. Therefore, when an abnormality occurs, it is possible to improve the safety of the subject by preventing excessive output of ultrasonic waves to the subject. Further, the protection circuit only needs to include at least a switch element and a voltage detection circuit, and the circuit scale and cost burden can be suppressed.

  The threshold voltage 41 (Vth) is preferably a voltage sufficiently smaller than the Collapse voltage in consideration of safety margin. For example, when the Collapse voltage is 100V, the threshold voltage 41 (Vth) is set to about 80 to 90V.

(3. Second embodiment)
Next, a second embodiment will be described with reference to FIG.
FIG. 4 is a configuration diagram of the protection circuit 13a of the ultrasonic diagnostic apparatus 1a according to the second embodiment.

  In the first embodiment, the protection circuit 13 is described as controlling the DC bias of one vibration element 3. However, in the second embodiment, the protection circuit 13 a applies the DC bias of a plurality of vibration elements 3. Control all at once.

  The electrodes 25-1, 25-2, ... and the electrodes 26-1, 26-2, ... of the plurality of vibration elements 3-1, 3-2, ... constituting the ultrasonic probe 2 are respectively parallel to each other. After being connected, the resistor 32 and the resistor 33 are connected.

As described above, in the second embodiment, it is possible to control the DC bias of a plurality of vibration elements by one protection circuit. Therefore, the circuit scale can be reduced as compared with the case where a protection circuit is provided for each vibration element.
For example, 16 protection circuits are provided, and each protection circuit controls the DC bias of 8 vibration elements, whereby the DC bias of 128 vibration elements as a whole can be controlled.

(4. Third embodiment)
Next, a third embodiment will be described with reference to FIG.
FIG. 5 is a configuration diagram of the protection circuit 13b of the ultrasonic diagnostic apparatus 1b according to the third embodiment.

  In the first embodiment, the switch element 31 has been described as being driven based on the signal output from the voltage detection circuit 34. However, in the third embodiment, the switch element 31 is driven from the external control device 37. It can also be made.

The protection circuit 13b includes an adder 36 and an external control device 37 in addition to the switch element 31, the resistor 32, the resistor 33, the voltage detection circuit 34, and the coupling circuit 35.
The adder 36 is provided at a connection point between the coupling circuit 35 and the external control device 37. An output signal from the voltage detection circuit 34 and an output signal from the external control device 37 are input to the adder 36. The adder 36 performs an addition process on the output signal from the voltage detection circuit 34 and the output signal from the external control device 37 and outputs a drive signal to the switch element 31. When the output signal from at least one of the voltage detection circuit 34 and the external control device 37 is a drive signal indicating an open state (OFF), the adder 36 outputs an OFF signal to the switch element 31 and is in an open state. (OFF)

As described above, in the third embodiment, similarly to the first embodiment, when an abnormality occurs, the switch element 31 is opened (OFF) based on the output signal from the voltage detection circuit 34, whereby the subject is examined. Therefore, it is possible to improve the safety of the subject by preventing an excessive output of ultrasonic waves.
Further, by using the external control device 37, the switch element 31 can be opened (OFF) at an arbitrary timing. For example, when a predetermined time elapses in the non-operation state, an OFF signal can be output from the external control device 37, and the switch element 31 can be brought into an open state (OFF). Thereby, power consumption can be reduced.
The external control device 37 may be any device that can output a drive signal for the switch element 31. As the external control device 37, for example, a one-chip microcomputer in which a program for realizing each function is written can be used.

(5. Screen display)
Next, screen display in the ultrasonic diagnostic apparatus 1 will be described with reference to FIG.
FIG. 6 is a diagram showing a screen display on the display unit 9 of the ultrasonic diagnostic apparatus 1. FIG. 6A shows a screen 51 when normal, and FIG. 6B shows a screen 55 when abnormality occurs.

  When the DC bias voltage is less than the threshold voltage and in a normal state, the ultrasound diagnostic apparatus 1 displays an ultrasound image 52 on the screen 51. On the other hand, when the DC bias voltage reaches the threshold voltage and the protection circuit 13 is activated and the switch element 31 is opened (OFF), a message 56 is displayed on the screen 55. The message 56 is, for example, a message for warning the occurrence of an abnormality, a message for notifying the power-off, or a message for instructing power-on again.

  As a result, the examiner can confirm the occurrence of an abnormality and perform a recovery operation on the screen display of the display unit 9.

  The preferred embodiments of the ultrasonic probe and the ultrasonic diagnostic apparatus according to the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea disclosed in the present application, and these are naturally within the technical scope of the present invention. Understood.

Configuration diagram of the ultrasonic diagnostic apparatus 1 1 is a configuration diagram of a protection circuit 13 according to the first embodiment. Characteristic diagram showing the relationship between DC bias voltage and ultrasonic output The block diagram of the protection circuit 13a which concerns on 2nd Embodiment. The block diagram of the protection circuit 13b which concerns on 3rd Embodiment The figure which shows the screen display in the display part 9 of the ultrasonic diagnosing device 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a, 1b ......... Ultrasonic diagnostic apparatus 2 ......... Ultrasonic probe 3 ......... Vibration element 4 ......... Main body 5 ......... Transmission circuit 6 ......... Bias circuit 7 ......... Reception circuit 8... Image processing section 9... Display section 10... Transmission / reception separation circuit 11... Control section 12 ... Operation section 13, 13a, 13b ... Protection circuit 14 ... Cable 21 ... DC power supply 22 ......... Capacitor 23 ......... AC pulse signal source 24 ......... Receiving amplifier (preamplifier)
25, 26 ......... Electrode 31 ......... Switch element 32, 32 ......... Resistance 34 ......... Voltage detection circuit 35 ......... Coupling circuit 36 ......... Adder 37 ......... External control device 41 ... … Threshold voltage 51,55 ……… Screen 52 ……… Ultrasound image 56 ……… Message

Claims (6)

In an ultrasonic probe comprising a pair of electrodes and a vibrator having a plurality of vibration elements whose ultrasonic transmission / reception sensitivity changes according to a bias voltage applied between the electrodes by a bias power source,
A switch element provided between the electrode and the bias power source;
A voltage detection circuit that is provided between the electrodes, detects a bias voltage applied between the electrodes, and outputs a drive signal to the switch element according to the magnitude of the detected bias voltage;
An ultrasonic probe comprising:   The ultrasonic probe according to claim 1, wherein the voltage detection circuit outputs an OFF signal to the switch element when detecting a predetermined threshold voltage.   The ultrasonic probe according to claim 1, further comprising a coupling circuit provided between the voltage detection circuit and the switch element and separating the high-voltage circuit side and the low-voltage circuit side. Tentacles. An external control device that outputs a drive signal to the switch element independently of the voltage detection circuit;
An adder that adds the drive signal from the external control device and the drive signal from the voltage detection circuit to output to the switch element;
The ultrasonic probe according to any one of claims 1 to 3, further comprising: An ultrasound probe that transmits / receives ultrasound to / from a subject, an image processing unit that configures an ultrasound image based on an ultrasound reception signal output from the ultrasound probe, and the ultrasound image is displayed In an ultrasonic diagnostic apparatus comprising a display unit,
The ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic probe is the ultrasonic probe according to claim 1.   The ultrasonic diagnostic apparatus according to claim 5, wherein when the switch element is opened, a warning is displayed on the display unit.

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