JP5842533B2 - Ultrasonic probe and ultrasonic inspection device - Google Patents

Description

  The present invention relates to an ultrasonic probe using a MUT (Micromachining Ultrasonic Transducer) element and an ultrasonic inspection apparatus using the same. In particular, the present invention relates to a wide band and high sensitivity of an ultrasonic probe for three-dimensional observation of a living body.

  The ultrasonic inspection apparatus transmits an ultrasonic beam from the ultrasonic probe to the subject, receives an ultrasonic signal reflected from the inside of the subject (hereinafter referred to as an ultrasonic echo), and receives information on the inside of the subject. It is a device to obtain. In this ultrasonic inspection apparatus, the higher the frequency of the ultrasonic wave transmitted from the ultrasonic probe, the higher the resolution. However, when performing in-vivo observation of a living body, the depth of arrival of the ultrasonic wave is shallower as the frequency of the ultrasonic wave is higher. The lower, the deeper. Therefore, in order to obtain a high-resolution image from a deep part to a shallow part, an ultrasonic probe capable of transmitting and receiving broadband ultrasonic waves is desired.

  Conventionally, an ultrasonic probe is configured by arranging a large number of piezoelectric vibrators made of a piezoelectric ceramic represented by PZT (lead zirconate titanate). In this configuration, as a method of expanding the band of ultrasonic waves to be transmitted and received, a configuration in which transducers having different resonance frequencies are arranged in the slice direction (for example, Patent Document 1), or a transducer having different resonance frequencies in the array direction is arranged. The structure (for example, patent document 2) etc. which do is proposed.

  However, such a method can be realized with a one-dimensional probe in which transducers are arranged in a row, but it is difficult to realize with a two-dimensional array probe that has been increasingly demanded in recent years. In order to make a conventional one-dimensional probe structure two-dimensional as it is, there are problems in terms of microfabrication, wiring, and electrical impedance. There are vibrators with distributions in the slice direction and vibrators with different thicknesses. In addition, the difficulty level increases and is not realistic.

  As a configuration suitable for such a two-dimensional array probe, a pMUT (Piezoelectric Microtransducing Ultratransducer) element and a cMUT (Capacitive Microtransducing Ultracapacitor Ultratransducer element) have recently been used. These transducers are formed by using a semiconductor manufacturing technique, and have advantages such as the possibility of increasing the number of arrays and the ease of integration with circuits. On the other hand, when such a transducer is used as an ultrasonic probe, it has a problem that it is difficult to satisfy simultaneously the high resonance frequency, the wide frequency band to be transmitted / received, the size of transmission output and reception sensitivity, etc. doing.

  As a countermeasure against this, pMUT has been proposed to improve sensitivity by structuring a piezoelectric layer (for example, Patent Document 4). Moreover, in cMUT, the structure which aimed at coexistence of a resonance frequency maintenance and a sensitivity improvement by providing a recessed part in the membrane surface and reducing the density of a membrane is proposed (for example, patent document 4).

JP-A-6-121390 JP 2005-277788 A JP 2011-15423 A JP 2009-182838 A

  As described above, the conventional bulk type vibrators described in Patent Documents 1 and 2 have problems such as fine processing, wiring, and electrical impedance, and are not suitable for a two-dimensional array probe.

  Further, although the cMUT described in Patent Document 3 can realize an improvement in reception sensitivity and wideband characteristics, when viewed as a transmission element, the sound pressure of the output ultrasonic wave is greatly inferior as compared with a conventional bulk type configuration.

  Moreover, although the pMUT element described in Patent Document 4 can be expected to have a larger transmission output than the cMUT, no mention is made regarding compatibility with wideband characteristics.

  The present invention solves the above-described conventional problems, and provides a two-dimensional array probe that improves the transmission output and reception sensitivity of a MUT element, particularly a pMUT, and has both wideband characteristics. An object of the present invention is to provide an ultrasonic inspection apparatus capable of obtaining a wide range and clear ultrasonic image by using this ultrasonic probe.

In order to achieve the above object, an ultrasonic probe of the present invention includes a plurality of unit transducers and an external force generator, the unit transducers are two-dimensionally arranged, and at least one of the unit oscillations. The child includes at least a pedestal portion, a vibrating portion formed on the pedestal portion, and a plurality of MUTs (Micromachining Ultrasounds) formed of a piezoelectric film formed on the upper surface of the vibrating portion with the first electrode formed on the upper surface. The plurality of MUT elements are electrically connected to each other, a space is provided in the pedestal, and the external force generator applies a bias voltage to the piezoelectric film. Then, the piezoelectric film is distorted and an external force is applied to the vibration part to adjust the resonance frequency .

  With this configuration, the center frequency of the ultrasonic wave transmitted and received by the unit transducer can be adjusted.

  Further, in this configuration, at the time of transmitting ultrasonic waves, it is possible to control so that an external force different from that of other MUT elements is applied to some MUT elements in the same unit transducer. Thereby, at least two ultrasonic waves having different center frequencies are generated from the same unit transducer, and broadband ultrasonic waves can be transmitted.

  Further, when receiving the ultrasonic wave, the external force applied to the vibrating part can be controlled in accordance with the passage of time after the ultrasonic wave is transmitted into the subject. As a result, a frequency band with high reception sensitivity can be effectively set according to the depth at which the ultrasonic echo returns, and apparently wideband and high sensitivity characteristics can be obtained.

  The ultrasonic inspection apparatus according to the present invention performs beam forming processing using the ultrasonic probe, a receiving unit that digitally converts a signal detected by the ultrasonic probe, and a signal digitally converted by the receiving unit. The signal processing unit includes an image processing unit that generates a three-dimensional image based on the three-dimensional data obtained by the signal processing unit, and a display unit that displays the three-dimensional image. With this configuration, a wide and clear ultrasonic image can be obtained.

  Since the ultrasonic probe and the ultrasonic inspection apparatus of the present invention can adjust the center frequency of ultrasonic waves to be transmitted and received, the frequency band can be set according to the application such as the depth of the region to be inspected. This is economical because a single probe can be used for a plurality of purposes.

  In addition, when a plurality of MUT elements included in the same unit vibrator are controlled so that ultrasonic waves having different center frequencies are generated, broadband ultrasonic waves can be transmitted. Furthermore, at the time of reception, by shifting the frequency band with high reception sensitivity with the passage of time, it is possible to set according to the depth of return of ultrasonic echo, and apparently wideband and highly sensitive signal detection is possible Become.

  Therefore, by using the ultrasonic probe according to the present invention, it is possible to realize a high quality ultrasonic inspection apparatus in a wide range from a shallow part to a deep part.

1 is a block diagram showing a schematic configuration of an ultrasonic inspection apparatus according to a first embodiment of the present invention. 1 is a configuration diagram showing the overall configuration of an ultrasonic probe according to a first embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing which showed the structure of the vibrator | oscillator unit concerning Embodiment 1 of this invention, (a) is a top view, (b) is a side view in AA cross section. FIG. 2 is a block diagram showing a schematic configuration of an ultrasonic inspection apparatus according to a second embodiment of the present invention. 1 is a configuration diagram showing the overall configuration of an ultrasonic probe according to a second embodiment of the present invention. Sectional drawing which showed the structure of the vibrator | oscillator unit concerning Embodiment 2 of this invention. Sectional drawing which showed the structure of the vibrator | oscillator unit concerning Embodiment 3 of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same reference number is attached | subjected to the same component and description is abbreviate | omitted.

(Embodiment 1)
FIG. 1 is a block diagram showing a schematic configuration of an ultrasonic inspection apparatus 10 according to the first embodiment of the present invention. The ultrasonic inspection apparatus 10 transmits an ultrasonic wave to the subject 11, generates an ultrasonic probe 12 that receives an ultrasonic signal reflected inside the subject 11, and a drive signal for transmitting the ultrasonic wave. And a signal processing for performing digital beam forming using the signal output from the transmission / reception unit 13 and the transmission / reception unit 13 that amplifies and digitally converts the signal detected by the ultrasonic probe 12 and outputs the signal. Unit 14, image processing unit 15 that performs a rendering process of a three-dimensional image based on the three-dimensional data generated by signal processing unit 14, and an image display that displays an image based on the processed image data Unit 16, control unit 17 that controls transmission / reception unit 13 to generate a drive signal at a predetermined timing, and the back surface of the transducer unit of ultrasonic probe 12 And a force adjusting portion 18 for adjusting the air pressure. The transmission / reception unit 13, the signal processing unit 14, the image processing unit 15, the image display unit 16, and the control unit 17 are stored in the inspection apparatus body 19, and a plurality of signal lines are connected to the ultrasonic probe 12. They are connected by a probe cable that covers the cables together.

  FIG. 2 is a configuration diagram showing the overall configuration of the ultrasonic probe 12 according to the first embodiment of the present invention. As shown in FIG. 2, the ultrasonic probe 12 includes a transducer unit 22 that transmits and receives ultrasonic waves into the probe case 21, a pressure chamber 23 that maintains the pressure on the back surface of the transducer unit 22 at a predetermined pressure, and vibration. And a printed circuit board 24 on which a plurality of signal lines for inputting / outputting electrical signals to / from unit vibrators in the slave unit 22 are printed. Further, the ultrasonic probe 12 is connected to the inspection apparatus main body 19 via a probe cable 25.

  Here, the external force adjusting unit 18 is configured to be able to adjust the pressure inside the pressure chamber 23.

  The transducer unit 22 is composed of a transducer array in which unit transducers composed of a plurality of pMUT elements are two-dimensionally arranged, and an ultrasonic pulse is generated by applying a pulsed voltage to each unit transducer. Is configured to occur. At this time, the generated ultrasonic waves can be focused and deflected by supplying a drive voltage subjected to delay processing to the electrodes of each unit transducer from the transmission / reception unit 13. With this configuration, the ultrasonic probe 12 is configured to perform sector scanning by transmitting ultrasonic waves in a three-dimensional direction.

  3A and 3B are explanatory views showing the structure of the vibrator unit 22 according to the first embodiment of the present invention, in which FIG. 3A is a top view and FIG. 3B is a side view in the AA section.

  As shown in FIG. 3A, the vibrator unit 22 is configured by, for example, two-dimensionally arranging unit vibrators 32 including four pMUT elements 31. Each pMUT element is represented by an upper electrode 33 made of a metal thin film such as platinum (Pt), gold (Au), and aluminum (Al), and PZT (lead zirconate titanate) as shown in FIG. A piezoelectric film 34 made of piezoelectric ceramic, etc., a metal film such as copper (Cu), chromium (Cr), etc., and a diaphragm 35 that also serves as a lower electrode, and a pedestal 36 made of a rigid material. ing. The space 37 between the pedestals 36 is configured to have the same atmospheric pressure as the pressure chamber 23, and by adjusting the atmospheric pressure in the pressure chamber 23 with the external force adjustment unit 18, an atmospheric pressure difference is generated on both sides of the diaphragm 35, The diaphragm 35 is configured to give an external force. When the external force is applied to the diaphragm 35 in this way, the resonance frequency of the vibrator unit 22 can be adjusted.

  Further, as shown in FIG. 3A, the upper electrode 33 of the pMUT element 31 is connected for each unit vibrator, and is individually connected to the printed circuit board 24 shown in FIG. Similarly, the drawer portion 35a of the diaphragm 35 is connected to the printed circuit board 24. With this configuration, a voltage can be applied to the piezoelectric film 34 independently for each unit vibrator.

  Note that the materials of the upper electrode 33, the piezoelectric film 34, and the diaphragm 35 described above are examples, and any materials may be used as long as they have the same function.

  Next, the operation of the ultrasonic inspection apparatus 10 according to the first embodiment configured as described above will be specifically described with reference to FIGS.

  1 and 2, first, the control unit 17 controls the transmission / reception unit 13 so as to generate a drive signal at a predetermined timing. The transmission / reception unit 13 performs a delay process for focusing and deflecting the ultrasonic wave, and the probe. A drive signal is transmitted to the ultrasonic probe 12 via a signal line collected in the cable 25.

  The delayed drive signal is sent to the transducer unit 22 via the printed circuit board 24, and a predetermined wavefront is formed by emitting ultrasonic waves from each unit transducer with a predetermined time difference. An ultrasonic beam is transmitted.

  The operation of transmitting this ultrasonic wave will be specifically described with reference to FIG. First, when a drive signal is transmitted from the transmission / reception unit 13 to the vibrator unit 22, a pulsed voltage is applied between the upper electrode 33 configured to sandwich the piezoelectric film 34 and the vibration plate 35 accordingly. Is done. When a voltage is applied in the thickness direction, the piezoelectric film 34 expands and contracts in a direction perpendicular to the piezoelectric film 34 to bend the vibration plate 35, and ultrasonic waves are generated by this vibration.

  Here, the center frequency of the ultrasonic wave generated by the transducer unit 22 is determined by the rigidity (spring constant) of the diaphragm 35. Accordingly, when the ultrasonic pressure is transmitted and the external pressure is applied to the diaphragm 35 by adjusting the air pressure in the space 37, the resonance frequency of the generated ultrasonic wave can be shifted. In the present embodiment, the inspection is performed by adjusting the center frequency of the ultrasonic wave transmitted and received in advance according to the application. Thereby, it is not necessary to inspect while exchanging a plurality of probes having different frequency bands, and one probe can correspond to a plurality of inspection parts.

  The ultrasonic wave transmitted from the ultrasonic probe 12 is reflected by the reflective tissue inside the subject 11, propagates to the surface of the subject 11 as an ultrasonic echo, and vibrates the transducer unit 22.

  When the diaphragm 35 of each pMUT element vibrates due to the ultrasonic echo, the piezoelectric film 34 is pulled and compressed in a plane to generate distortion, and a voltage is generated in the thickness direction of the piezoelectric film 34 according to the distortion. At this time, by detecting the voltage between the upper electrode 33 and the diaphragm 35, vibration corresponding to the ultrasonic echo can be detected. Further, at this time, if the pressure in the space 37 is adjusted so as to easily vibrate in a specific frequency band, generally the central frequency band of the transmitted ultrasonic wave, the reception sensitivity is improved.

  Referring back to FIG. 1 again, the signal detected by the ultrasonic probe 12 is sent to the transmission / reception unit 13, amplified and digitally converted by the transmission / reception unit 13, and the ultrasonic transmission path (hereinafter referred to as sound ray) by the signal processing unit 14. The beam forming process is performed on the area along the line.

  The above operation is performed while scanning the sound ray of the ultrasonic wave transmitted from the ultrasonic probe 12 in the subject, and information on the entire examination region is calculated and stored in the image memory in the signal processing unit 14. . The three-dimensional data stored in the image memory is subjected to a three-dimensional image rendering process by the image processing unit 15, and an image is displayed on the image display unit 16.

  As described above, the ultrasonic inspection apparatus 10 according to the first embodiment can freely set the center frequency according to the application when transmitting and receiving ultrasonic waves into the subject. Thereby, when it is desired to look at a shallow part inside the subject or when it is desired to look at a deep part, an examination can be performed by selecting an optimum frequency band without exchanging the probe. Therefore, since one probe can be used for a wide range of applications, it is economical.

  In the present embodiment, the AD conversion of the detected signal is performed by the transmission / reception unit 13 in the inspection apparatus body 19. However, when the number of unit transducers 32 in the ultrasonic probe 12 is large, the analog signal remains as it is. If it is going to transmit a detection signal, many signal lines will be needed and the probe cable 25 will become thick and hard. As a result, handling becomes worse, so that part or all of the functions of the transmission / reception unit 13 may be provided integrally with the ultrasonic probe 12 and the digitally converted signal may be communicated by the probe cable 25. .

  In the present embodiment, an external force is applied to the diaphragm 35 using atmospheric pressure. However, a bias voltage is applied between the upper electrode 33 and the diaphragm 35 to distort the piezoelectric film 34 to vibrate. Stress may be applied to the plate 35. Even if comprised in this way, since the resonant frequency can be adjusted, the effect similar to this Embodiment is acquired.

(Embodiment 2)
In the present embodiment, since only the external force control unit and the ultrasonic probe 12 are different from the first embodiment, description of other components is omitted. Also, the same constituent elements as those of the first embodiment are given the same numbers, and description thereof is omitted.

  FIG. 4 is a block diagram showing a schematic configuration of the ultrasonic inspection apparatus according to the second embodiment of the present invention. In this block diagram, the only difference from the first embodiment is the external force control unit 20 stored in the inspection apparatus main body 19. The external force control unit 20 is configured to control an external force applied to the vibration unit of the pMUT element when the ultrasonic probe 12 transmits / receives ultrasonic waves.

  FIG. 5 is a configuration diagram showing the overall configuration of the ultrasonic probe 12 according to the second embodiment of the present invention. As shown in FIG. 5, the ultrasonic probe 12 includes a transducer unit 22 that transmits and receives ultrasonic waves inside a probe case 21, a magnetostrictive element 41 for adjusting the resonance frequency of the transducer unit 22, and a printed circuit board 24. And. Further, the ultrasonic probe 12 is connected to the inspection apparatus main body 19 via a probe cable 25.

  FIG. 6 is a cross-sectional view showing the structure of the vibrator unit 22 according to the second embodiment of the present invention. As in the first embodiment, each pMUT element includes an upper electrode 33, a piezoelectric film 34, a diaphragm 35, and a pedestal 36, and is configured by arranging unit vibrators 32 two-dimensionally. ing. The upper electrode 33 is connected to each unit vibrator, and is configured to apply a voltage independently to each unit vibrator.

  The structure of the vibrator unit 22 is different from that of the first embodiment in that it is disposed on the back surface of the backing material 42 made of an elastic material disposed between the pedestals 36 and the backing material 42 of some pMUT elements. That is, the structure includes a backing material 43, a magnetostrictive element 41 connected to the backing material 43, and a base 44.

  Here, the backing material 43 is disposed in at least one of the pMUT elements included in the unit vibrator 32. When the magnetostrictive element 41 is distorted, an external force is applied to a predetermined diaphragm via the backing material 43 and the backing material 42. It is configured to join. That is, in the present embodiment, by controlling the strain of the magnetostrictive element 41, an external force is applied to a predetermined diaphragm, and the resonance frequency can be controlled.

  In addition, each pMUT element is comprised by the same structure, and when the external force is not applied, it is comprised so that a resonant frequency may correspond.

  Next, the operation of the ultrasonic inspection apparatus 10 according to the present embodiment configured as described above will be specifically described with reference to FIGS.

  First, as in the first embodiment, a drive signal is transmitted from the transmission / reception unit 13 of the inspection apparatus body 19 to the ultrasonic probe 12, and a pulsed voltage is applied to each unit transducer of the transducer unit 22. At this time, a voltage is applied to the piezoelectric film 34 in the thickness direction, and it expands and contracts in a direction perpendicular to the piezoelectric film 34 to bend the vibration plate 35, and ultrasonic waves are generated by this vibration.

  At this time, when a drive signal is transmitted from the external force control unit 20 and a current is passed through a coil wound around the magnetostrictive element 41, the magnetostrictive element 41 is distorted and deformed, and at least one pMUT in the unit vibrator 32 is obtained. The element receives an external force on the diaphragm 35. The pMUT element that has received an external force changes the rigidity of the diaphragm 35, so that the resonance frequency is different from that of the other pMUT elements in the same unit vibrator, and ultrasonic waves having different center frequencies are transmitted. For this reason, an ultrasonic wave with a wide band is transmitted from the unit transducer 32.

  The ultrasonic wave transmitted from the ultrasonic probe 12 is reflected by the reflective tissue inside the subject 11, propagates to the surface of the subject 11 as an ultrasonic echo, and vibrates the transducer unit 22.

  When the diaphragm 35 of each pMUT element vibrates due to the ultrasonic echo, the piezoelectric film 34 is pulled and compressed in a plane to generate distortion, and a voltage is generated in the thickness direction of the piezoelectric film 34 according to the distortion. At this time, by detecting the voltage between the upper electrode 33 and the diaphragm 35, vibration corresponding to the ultrasonic echo can be detected.

  By the way, although the ultrasonic wave transmitted from the ultrasonic probe 12 has a higher resolution as the frequency is higher, the depth of arrival is shallower as the frequency is higher and deeper as the frequency is lower. Therefore, a signal detected in a short time after transmitting an ultrasonic wave into the subject has a high frequency component, but a high frequency component of the signal detected with time decreases. Therefore, when the frequency characteristic of the reception sensitivity of the transducer unit 22 is shifted from a high frequency band to a low frequency band as time passes after ultrasonic transmission, high reception sensitivity can be realized in a wide frequency band. .

  In the present embodiment, the external force control unit 20 controls the magnetostrictive element 41 according to the passage of time after ultrasonic transmission to apply an external force to the diaphragms 35 of some pMUT elements, and sets the resonance frequency of the pMUT elements to the time. Shift according to progress. As a result, the center frequency of the reception sensitivity changes with time, and ultrasonic echoes generated in a wide range from a shallow part to a deep part are detected with high sensitivity.

  Next, the signal detected by the ultrasonic probe 12 is sent to the transmission / reception unit 13, amplified and digitally converted by the transmission / reception unit 13, and the signal forming unit 14 performs a beam forming process on a region along the acoustic ray of the ultrasonic wave. Done.

  The above operation is performed while scanning the sound ray of the ultrasonic wave transmitted from the ultrasonic probe 12 in the subject, and information on the entire examination region is calculated and stored in the image memory in the signal processing unit 14. . The three-dimensional data stored in the image memory is subjected to a three-dimensional image rendering process by the image processing unit 15, and an image is displayed on the image display unit 16.

  As described above, the ultrasonic inspection apparatus 10 of the second embodiment shifts the resonance frequency of a part of the pMUT element included in the unit transducer when transmitting the ultrasonic wave into the subject. A broadband ultrasonic wave can be transmitted. Also, when receiving ultrasonic echoes, it is possible to detect ultrasonic echoes generated in a wide range from shallow parts to deep parts with high sensitivity by shifting the frequency characteristics of reception sensitivity over time. it can. Thereby, it is possible to realize an ultrasonic inspection apparatus capable of acquiring a wide range of high-quality three-dimensional images.

  In this embodiment, the magnetostrictive element is used for generating the external force. However, the same effect can be obtained by using an element capable of controlling the deformation amount such as a piezoelectric element.

(Embodiment 3)
In the present embodiment, since only the ultrasonic probe 12 is different from the second embodiment, description of other components is omitted. Also, the same constituent elements as those of the first embodiment are given the same numbers, and description thereof is omitted.

  FIG. 7 is a cross-sectional view showing the structure of the transducer unit 22 according to the third embodiment of the present invention. As in the second embodiment, each pMUT element includes an upper electrode 33, a piezoelectric film 34, a diaphragm 35, and a pedestal 36, and is configured by arranging unit vibrators 32 two-dimensionally. ing. The upper electrode 33 is connected to each unit vibrator, and is configured to apply a voltage independently to each unit vibrator.

  The present embodiment is different from the second embodiment in that a metal thin film such as platinum (Pt), gold (Au), aluminum (Al), etc. is placed on the opposite side of the diaphragm 35 with a space 37 between the pedestals 36 interposed therebetween. The substrate 52 on which the electrode 51 made of is formed is disposed. Here, the electrode 51 includes at least two systems of electrodes 51a and 51b, and each unit vibrator is configured to include electrodes of both systems. Further, the electrode 51a and the electrode 51b are connected to electrodes of the same system through the wiring 53a and the wiring 53b, and are configured so that a voltage can be applied independently for each system.

  The electrode 51 and the diaphragm 35 are separated from each other at least when the piezoelectric film 34 does not vibrate, and an electrostatic force (electrostatic attractive force) is generated by applying a voltage between the electrode 51 and the diaphragm 35. And an external force is applied to the diaphragm 35. Moreover, each pMUT element is comprised by the same structure, and when the external force is not applied, it is comprised so that a resonant frequency may correspond.

  Next, the operation of the ultrasonic inspection apparatus 10 of the third embodiment configured as described above will be specifically described with reference to FIG.

  First, as in the first embodiment, a drive signal is transmitted from the transmission / reception unit of the inspection apparatus body to the ultrasonic probe, and a pulsed voltage is applied to each unit transducer of the transducer unit 22. At this time, a voltage is applied to the piezoelectric film 34 in the thickness direction, and it expands and contracts in a direction perpendicular to the piezoelectric film 34 to bend the vibration plate 35, and ultrasonic waves are generated by this vibration.

  Here, when a voltage is applied to the electrode 51, an electrostatic force is generated between the electrode 51 and the diaphragm 35. This electrostatic force is inversely proportional to the square of the distance between the two electrodes and increases in proportion to the square of the applied voltage. Therefore, as the applied voltage increases and the distance decreases, the restoring force of the diaphragm 35 decreases and the resonance frequency. Will shift to the low frequency side.

  At this time, when different voltages are applied to the electrodes 51a and 51b, ultrasonic waves having different center frequencies are transmitted from the pMUT elements in the unit vibrator 32, respectively. For this reason, an ultrasonic wave with a wide band is transmitted from the unit transducer 32.

  The ultrasonic wave transmitted from the ultrasonic probe 12 is reflected by the reflective tissue inside the subject 11, propagates to the surface of the subject 11 as an ultrasonic echo, and vibrates the transducer unit 22.

  When the diaphragm 35 of each pMUT element vibrates due to the ultrasonic echo, the piezoelectric film 34 is pulled and compressed in a plane to generate distortion, and a voltage is generated in the thickness direction of the piezoelectric film 34 according to the distortion. At this time, by detecting the voltage between the upper electrode 33 and the diaphragm 35, vibration corresponding to the ultrasonic echo can be detected.

  At this time, the same voltage is applied to the electrodes 51a and 51b, and the applied voltage is changed as time passes. Specifically, control is performed so that the frequency characteristic of the reception sensitivity of the transducer unit 22 is shifted from a high frequency band to a low frequency band in accordance with the passage of time after ultrasonic transmission. By controlling in this way, it is possible to realize high reception sensitivity in an apparent wide frequency band. Thereby, an ultrasonic echo generated in a wide range from a shallow part to a deep part is detected with high sensitivity.

  Next, the signal detected by the ultrasonic probe 12 is sent to the transmission / reception unit 13, amplified and digitally converted by the transmission / reception unit 13, and the signal forming unit 14 performs a beam forming process on a region along the acoustic ray of the ultrasonic wave. Done.

  The above operation is performed while scanning the sound ray of the ultrasonic wave transmitted from the ultrasonic probe 12 in the subject, and information on the entire examination region is calculated and stored in the image memory in the signal processing unit. The three-dimensional data stored in the image memory is subjected to a three-dimensional image rendering process by the image processing unit, and an image is displayed on the image display unit.

  As described above, the ultrasonic inspection apparatus 10 according to the third embodiment adjusts the resonance frequency by substantially changing the spring constant of the diaphragm 35 by the electrostatic spring effect, thereby improving the transmission / reception characteristics. Can be improved. Specifically, when transmitting ultrasonic waves into the subject, wideband ultrasonic waves can be transmitted by shifting a part of the resonance frequency of the pMUT element included in the unit transducer. Also, when receiving ultrasonic echoes, it is possible to detect ultrasonic echoes generated in a wide range from shallow parts to deep parts with high sensitivity by shifting the frequency characteristics of reception sensitivity over time. it can.

  Further, unlike the second embodiment, the resonance frequency of all the pMUT elements can be controlled, so that the control of the ultrasonic wave band to be transmitted and the center frequency control of the reception sensitivity can be performed more accurately and in a wider range. An ultrasonic inspection apparatus capable of acquiring a high-quality three-dimensional image can be realized.

  As described above, according to the present invention, a highly sensitive two-dimensional array probe can be realized over a wide band. Thereby, it is possible to realize an ultrasonic diagnostic apparatus having a wide range and high image quality from a shallow part to a deep part.

DESCRIPTION OF SYMBOLS 10 Ultrasonic inspection apparatus 11 Subject 12 Ultrasonic probe 13 Transmission / reception part 14 Signal processing part 15 Image processing part 16 Image display part 17 Control part 18 External force adjustment part 19 Inspection apparatus main body 20 External force control part 21 Probe case 22 Transducer unit 23 Pressure chamber 24 Printed circuit board 25 Probe cable 31 pMUT element 32 Unit vibrator 33 Upper electrode 34 Piezoelectric film 35 Vibration plate 36 Base 37 Space 41 Magnetostrictive element 42 Backing material 43 Backing material 51 Electrode 51a, 51b Electrode 52 Substrate 53a, 53b Wiring

Claims (9)

A plurality of unit oscillators;
An external force generator,
The unit vibrators are two-dimensionally arranged,
At least one of the unit vibrators includes at least a pedestal portion, a vibration portion formed on the pedestal portion, and a piezoelectric film formed on the upper surface of the vibration portion with a first electrode formed on the upper surface. A plurality of MUT (Micromachining Ultrasound Transducer) elements;
The plurality of MUT elements are electrically connected to each other,
A space is provided in the pedestal,
The ultrasonic probe according to claim 1, wherein the external force generation unit adjusts a resonance frequency by applying a bias voltage to the piezoelectric film to distort the piezoelectric film and applying an external force to the vibration unit. An external force adjustment unit that adjusts the force applied to the vibration unit by the external force generation unit;
The ultrasonic probe according to claim 1, wherein an external force applied to the vibrating portion can be adjusted according to a depth of an in-vivo observation site. An external force control unit that controls the force that the external force generation unit applies to the vibration unit;
The ultrasonic probe according to claim 1, wherein a force applied to the vibrating portion can be controlled during transmission and reception of ultrasonic waves. When receiving ultrasound,
The ultrasonic probe according to claim 3, wherein the external force control unit is capable of controlling an external force applied to the vibration unit according to a lapse of time after transmitting the ultrasonic wave into the subject . When sending ultrasonic waves,
The ultrasonic probe according to claim 3, wherein the external force control unit can apply an external force different from that of other MUT elements to a part of the MUT elements in the same unit transducer. A plurality of unit oscillators;
An external force generator,
The unit vibrators are two-dimensionally arranged,
At least one of the unit vibrators includes at least a pedestal portion, a vibration portion formed on the pedestal portion, and a piezoelectric film formed on the upper surface of the vibration portion with a first electrode formed on the upper surface. A plurality of MUT (Micromachining Ultrasound Transducer) elements;
The plurality of MUT elements are electrically connected to each other,
A space is provided in the pedestal,
The ultrasonic probe according to claim 1, wherein the external force generator includes a backing material provided in the space of the pedestal portion, and a magnetostrictive element that applies an external force to the vibrating portion via the backing material. A plurality of unit oscillators;
An external force generator,
The unit vibrators are two-dimensionally arranged,
At least one of the unit vibrators includes at least a pedestal portion, a vibration portion formed on the pedestal portion, and a piezoelectric film formed on the upper surface of the vibration portion with a first electrode formed on the upper surface. A plurality of MUT (Micromachining Ultrasound Transducer) elements;
The plurality of MUT elements are electrically connected to each other,
A space is provided in the pedestal,
The ultrasonic probe according to claim 1, wherein the external force generator includes a backing material provided in the space of the pedestal portion and a piezoelectric element that applies an external force to the vibrating portion via the backing material. Beam forming using the ultrasonic probe according to any one of claims 1 to 7, a receiving unit that digitally converts a signal detected by the ultrasonic probe, and a signal digitally converted by the receiving unit An ultrasonic inspection apparatus comprising: a signal processing unit that performs processing; an image processing unit that generates a three-dimensional image based on three-dimensional data obtained by the signal processing unit; and a display unit that displays the three-dimensional image. The ultrasonic inspection apparatus according to claim 8, wherein a receiving unit that digitally converts a signal detected by the ultrasonic probe is disposed in the ultrasonic probe.

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