JP5439864B2 - Ultrasonic diagnostic equipment - Google Patents

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus that constructs a high-definition ultrasonic image.

  Ultrasound generally refers to sound waves of 16000 Hz or higher and can be examined non-destructively, harmlessly and in real time, and thus is applied to various fields such as defect inspection and disease diagnosis. For example, an ultrasound that scans the inside of the subject with ultrasound and images the internal state of the subject based on a reception signal generated from the reflected wave (echo) of the ultrasound coming from inside the subject. There is a diagnostic device. This ultrasonic diagnostic apparatus is smaller and less expensive for medical use than other medical imaging apparatuses, has no radiation exposure such as X-rays, is highly safe, and has a blood flow utilizing the Doppler effect. It has various features such as display capability. For this reason, an ultrasonic diagnostic apparatus includes a circulatory system (for example, coronary artery of the heart), a digestive system (for example, gastrointestinal), an internal system (for example, liver, pancreas, and spleen), and a urinary system (for example, kidney and bladder). Widely used in obstetrics and gynecology.

  An ultrasonic probe that transmits and receives an ultrasonic wave (ultrasonic signal) to a subject is used in the ultrasonic diagnostic apparatus. An ultrasonic probe uses a piezoelectric phenomenon to generate an ultrasonic wave (ultrasonic wave signal) by mechanical vibration based on an electric signal transmitted, and an ultrasonic wave generated due to mismatch of acoustic impedance inside a subject. A plurality of piezoelectric elements that receive a reflected wave of (ultrasonic signal) and generate a reception electric signal are provided, and the plurality of piezoelectric elements are arranged in a two-dimensional array, for example (for example, Patent Document 1). reference).

  Also, in recent years, harmonic imaging (Harmonic Imaging) is used to form an image of the internal state in the subject by using harmonic components instead of the frequency (fundamental frequency) component of the ultrasound transmitted from the ultrasound probe into the subject. ) Technology is researched and developed. In this harmonic imaging technology, the side lobe level is small compared to the level of the fundamental frequency component, the S / N ratio (Signal to Noise ratio) is improved, the contrast resolution is improved, and the beam width is increased by increasing the frequency. The lateral resolution improves, the sound pressure is small and the fluctuation in sound pressure is small at short distances, so that multiple reflections are suppressed. Compared to the case of using the fundamental wave, it has various advantages such as a greater depth speed.

  In harmonic imaging technology, a pulse having a single frequency component is transmitted, and an internal state image (ultrasound image) in the subject is constructed by harmonic components in the reflected wave from the subject. The ultrasonic wave of the harmonic component transmitted from other than the reflected wave from becomes a noise component, and it becomes impossible to construct an image of the internal state in the subject with high definition. On the other hand, an ultrasonic wave (ultrasonic signal) transmitted by the ultrasonic probe is generated by applying a pulse voltage to a piezoelectric element provided in the ultrasonic probe. Since the pulse voltage has a harmonic component, a harmonic component is also generated in the ultrasonic wave itself generated by the piezoelectric element. Therefore, since this harmonic component is received together with the reflected wave in the subject, it becomes a noise component and hinders the construction of a high-definition ultrasonic image.

  Proposals have been made to solve this problem. For example, a pulsar is provided with a plurality of switching elements to which different voltage values are individually supplied, and by driving on / off control of the plurality of switching elements, a drive pulse having a waveform that is at least equal in time is generated based on the different voltage values. Some are generated in a pulsar, generate ultrasonic waves closer to a sine wave, and reduce harmonic components (see, for example, Patent Document 2).

JP 2004-088056 A JP-A-8-238243

  The technique described in Patent Document 2 improves the monochromaticity such that the ultrasonic wave has a single frequency by bringing the voltage waveform applied to the piezoelectric element close to a sine wave. However, since the technique described in Patent Document 2 is to shape a rectangular wave-like voltage waveform before and after the time axis with a rectangular wave, the effect of making it close to a sine wave is small. Accordingly, it is difficult to construct a high-definition ultrasonic image because the effect of reducing harmonic components contained in ultrasonic waves transmitted by the piezoelectric element is small.

  An object of the present invention is to provide an ultrasonic diagnostic apparatus capable of reducing a harmonic component contained in an ultrasonic wave transmitted by a piezoelectric element in an ultrasonic probe and constructing a high-definition ultrasonic image. To do.

  The above object is achieved by the invention described below.

1. A plurality of first transmitting piezoelectric elements for transmitting a first ultrasonic signal into the subject;
The first transmission piezoelectric element is disposed in a stacked manner, and the first ultrasonic component transmitted by the first transmission piezoelectric element has an antiphase first phase with respect to at least one harmonic component of a predetermined order. A plurality of second transmitting piezoelectric elements that transmit two ultrasonic signals;
Wherein Ri first ultrasonic signal and the second reflected wave der generated by reflected ultrasonic waves and the ultrasonic signal is superimposed in the inside of the subject, a third greater than that contains a harmonic component of the predetermined order A plurality of receiving piezoelectric elements that receive sound wave signals and convert them into electrical signals;
An ultrasonic probe comprising:
A transmitter for driving the first transmitting piezoelectric element and the second transmitting piezoelectric element;
A receiver for driving the receiving piezoelectric element;
An image processing unit for generating an ultrasound image in the subject from the electrical signal;
An ultrasonic diagnostic apparatus comprising:

2. 2. The ultrasonic diagnostic apparatus according to 1, wherein the second transmission piezoelectric element is disposed at a distance of 1 mm or less from the first transmission piezoelectric element.
3. 3. The ultrasonic diagnostic apparatus according to claim 1 or 2, wherein the receiving piezoelectric element is stacked on the second transmitting piezoelectric element.
4). The first transmitting piezoelectric element and the second transmitting piezoelectric element are inorganic piezoelectric elements,
4. The ultrasonic diagnostic apparatus according to 3 above, wherein the receiving piezoelectric element is an organic piezoelectric element.
5. 2. The ultrasonic diagnostic apparatus according to 1 above, wherein the ultrasonic probe includes a transmission / reception piezoelectric element having both functions of the second transmission piezoelectric element and the reception piezoelectric element.
6). The transmitting and receiving piezoelectric element, ultrasonic diagnostic apparatus according to 5, characterized in that it is disposed from the first transmitting piezoelectric element within a distance of 1 mm.
7). The first transmitting piezoelectric element is an inorganic piezoelectric element,
7. The ultrasonic diagnostic apparatus according to 5 or 6, wherein the transmission / reception piezoelectric element is an organic piezoelectric element.

8 . 8. The ultrasonic diagnostic apparatus according to any one of 1 to 7 , wherein the predetermined order is a second order or a third order.

  It is possible to provide an ultrasonic diagnostic apparatus that can reduce a harmonic component contained in an ultrasonic wave transmitted by a piezoelectric element in an ultrasonic probe and construct a high-definition ultrasonic image.

It is a figure which shows the external appearance structure of the ultrasound diagnosing device in embodiment. It is a block diagram which shows the electrical structure of the ultrasonic diagnosing device in embodiment. It is a figure which shows the structure of the ultrasound probe in the ultrasound diagnosing device in embodiment. It is a schematic diagram which shows the outline | summary of the frequency of the ultrasonic wave which the ultrasonic probe of embodiment transmits. It is a schematic diagram which shows the outline | summary of the frequency of the ultrasonic wave which the ultrasonic probe of embodiment transmits. It is a figure which shows the other structure of the ultrasound probe in the ultrasound diagnosing device of embodiment. It is a figure which shows the other structure of the ultrasound probe in the ultrasound diagnosing device of embodiment. It is a schematic diagram which shows the outline | summary of the frequency of the ultrasonic wave which the ultrasonic probe of embodiment transmits. It is a schematic diagram of a circuit configuration example of the transmission side and the reception side of the embodiment. It is a schematic diagram of a circuit configuration example of the transmission side and the reception side of the embodiment. It is a flowchart of the self-check function process in an embodiment. It is a schematic diagram showing the frequency spectrum of the ultrasonic wave which the 1st ultrasonic signal and 2nd ultrasonic signal in an embodiment combined.

  Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to the embodiments described below. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted. Further, in this specification, as appropriate, a generic reference is used to indicate a reference numeral without a suffix, and an individual configuration is indicated by a reference numeral with a suffix.

[Configurations and operations of ultrasonic diagnostic equipment and ultrasonic probe]
Each configuration and operation of the ultrasonic diagnostic apparatus and the ultrasonic probe according to the present embodiment will be described with reference to FIGS. 1 to 8. FIG. 1 is a diagram illustrating an external configuration of an ultrasonic diagnostic apparatus according to an embodiment. FIG. 2 is a block diagram illustrating an electrical configuration of the ultrasonic diagnostic apparatus according to the embodiment. FIG. 3 is a diagram illustrating a configuration of an ultrasonic probe in the ultrasonic diagnostic apparatus according to the embodiment. 4 and 5 are schematic diagrams showing an outline of the frequency of the ultrasonic wave transmitted by the ultrasonic probe according to the embodiment. 6 and 7 are diagrams showing another configuration of the ultrasonic probe in the ultrasonic diagnostic apparatus of the embodiment. FIG. 8 is a schematic diagram illustrating an outline of the frequency of ultrasonic waves transmitted by the ultrasonic probe according to the embodiment.

  As shown in FIG. 1, the ultrasonic diagnostic apparatus S transmits ultrasonic waves (ultrasonic signals) to a subject H such as a living body (not shown) and also reflects reflected ultrasonic waves (reflected by the subject H) ( (Echo, ultrasonic signal) is connected to the ultrasonic probe 2 via the cable 3 and the ultrasonic probe 2 is connected to the ultrasonic probe 2 via the cable 3. By transmitting, the ultrasonic probe 2 transmits an ultrasonic wave to the subject H, and an ultrasonic wave according to the reflected wave of the ultrasonic wave from the subject H received by the ultrasonic probe 2. An ultrasonic diagnostic apparatus main body 1 that images an internal state of the subject H as an ultrasonic image based on a reception signal generated by the probe 2 is configured.

  For example, as shown in FIG. 2, the ultrasonic diagnostic apparatus main body 1 includes an operation input unit 11 for inputting a command for instructing diagnosis and data such as personal information of the subject H, and a cable to the ultrasonic probe 2. A transmission unit 12 that drives the ultrasonic probe 2 to generate ultrasonic waves by supplying a transmission signal of an electrical signal via 3, and receives a reception signal from the ultrasonic probe 2 via the cable 3. The receiving unit 13, the image processing unit 14 that generates an image (ultrasonic image) of the internal state in the subject H based on the received signal received by the receiving unit 13, and the received signal received by the receiving unit 13. Then, a check unit 17 that self-checks whether a harmonic component is removed from the ultrasonic wave transmitted by the ultrasonic probe 2, a storage unit 18 that stores a result obtained by the check unit 17, and image processing. In the subject H generated by the unit 14 The display unit 15 that displays the image of the internal state, and the operation input unit 11, the transmission unit 12, the reception unit 13, the image processing unit 14, the display unit 15, the check unit 17, and the storage unit 18 are controlled according to the function. And a control unit 16 that performs overall control of the ultrasound diagnostic apparatus S.

  An example of the ultrasonic probe (ultrasonic probe) 2 will be described with reference to FIG. The ultrasonic probe 2 includes one organic piezoelectric element and two inorganic piezoelectric elements.

  An inorganic piezoelectric element comprises an inorganic piezoelectric material, and an organic piezoelectric element comprises an organic piezoelectric material, each of which can convert signals between a received signal and an ultrasonic signal by utilizing a piezoelectric phenomenon. it can.

  For example, PZT can be used as the inorganic piezoelectric material. As the organic piezoelectric material, for example, a vinylidene fluoride polymer or a vinylidene fluoride (VDF) copolymer can be used.

  The ultrasonic probe 2 has a flat acoustic braking member 23, an acoustic matching layer 31 stacked on the acoustic braking member 23, an inorganic piezoelectric element array 4a, and an acoustic matching toward the subject H direction. The layer 26a, the inorganic piezoelectric element array 4b, the acoustic matching layer 26b, the organic piezoelectric element array 5, and the acoustic matching layer 27 laminated on the organic piezoelectric element array 5 are provided.

  The inorganic piezoelectric element array 4 a includes a plurality of inorganic piezoelectric elements 22 a, an acoustic separation unit 24 that is manufactured by filling a gap between the inorganic piezoelectric elements 22 with an acoustic separation material, and a common ground layered on the inorganic piezoelectric elements 22. And an electrode 25.

  The inorganic piezoelectric element array 4 b includes a plurality of inorganic piezoelectric elements 22 b, an acoustic separation unit 24 that is manufactured by filling a gap between the inorganic piezoelectric elements 22 with an acoustic separation material, and a common ground layered on the inorganic piezoelectric elements 22. And an electrode 25.

  The acoustic braking member 23 is made of a material that absorbs ultrasonic waves, and absorbs ultrasonic waves radiated from the plurality of inorganic piezoelectric elements 22 toward the acoustic braking member 23.

  The acoustic matching layer 31 has an acoustic impedance that is intermediate between the acoustic impedances of the acoustic braking member 23 and the inorganic piezoelectric element 22, and matches the acoustic impedance of the acoustic braking member 23 and the inorganic piezoelectric element 22.

  Each inorganic piezoelectric element 22 includes electrodes 102 and 103 on opposite surfaces of the piezoelectric element 101 made of an inorganic piezoelectric material. The plurality of inorganic piezoelectric elements 22 are two-dimensionally arranged in a plan view with a predetermined interval therebetween, and are disposed on the acoustic braking member 23.

  In addition, although not shown, a conductive pad for receiving an electric signal from the outside is provided below the acoustic braking member 23, and the conductive pad and the inorganic piezoelectric element 22a, and the conductive pad and the electrode of the inorganic piezoelectric element 22b are signal lines. It is connected.

  The plurality of inorganic piezoelectric elements 22 are configured to transmit ultrasonic waves. More specifically, an electrical signal is input to the plurality of inorganic piezoelectric elements 22 from the transmitter 12 via the cable 3, the conductive pad, and the signal line. The electric signal is input between the electrode 102 and the electrode 103 of the inorganic piezoelectric element 22. The plurality of inorganic piezoelectric elements 22 transmit ultrasonic signals by converting the electrical signals into ultrasonic signals.

  The acoustic separator 24 is made of a low acoustic impedance resin having a value that differs greatly from the acoustic impedance of the inorganic piezoelectric element 22. The acoustic separator 24 functions as an acoustic separator due to the great difference in acoustic impedance, and the plurality of inorganic piezoelectric elements 22. Has a function of reducing mutual interference. The acoustic separator 24 can reduce crosstalk between the inorganic piezoelectric elements 22.

  The common ground electrode 25 is made of a conductive material, is grounded by an unillustrated wiring, and is laminated in a straight line across the plurality of inorganic piezoelectric elements 22, whereby the common ground electrode 25 is formed in the inorganic piezoelectric elements 22. Each electrode 103 is electrically grounded.

  The acoustic matching layer 26a has an acoustic impedance intermediate between the acoustic impedances of the inorganic piezoelectric element array 4a and the inorganic piezoelectric element array 4b, and matches the acoustic impedance of the inorganic piezoelectric element array 4a and the inorganic piezoelectric element array 4b.

  The acoustic matching layer 26 b has an acoustic impedance that is intermediate between the acoustic impedances of the inorganic piezoelectric element array 4 b and the organic piezoelectric element array 5, and matches the acoustic impedance of the inorganic piezoelectric element array 4 b and the organic piezoelectric element array 5.

  The acoustic matching layer 27 is a member that matches the acoustic impedance of the organic piezoelectric element array 5 and the acoustic impedance of the subject H. The acoustic matching layer 27 has a shape that bulges in an arc shape, and has a function of an acoustic lens that converges ultrasonic waves transmitted toward the subject H.

  The organic piezoelectric element array 5 includes a piezoelectric element 105 made of a flat organic piezoelectric material having a predetermined thickness, a plurality of mutually separated electrodes 106 formed on one main surface of the piezoelectric element 105, and the piezoelectric element. This is a sheet-like piezoelectric element configured to include the electrode 107 formed uniformly over substantially the entire other surface of the element 105.

  By forming the plurality of electrodes 106 on one main surface of the piezoelectric element 105, the organic piezoelectric element array 5 includes a piezoelectric element including one electrode 107, the piezoelectric element 105, and the electrode 106 in a two-dimensional shape. Each piezoelectric element operates individually.

  The plurality of piezoelectric elements in the organic piezoelectric element array 5 do not need to be individually separated like the inorganic piezoelectric elements 22 in order to function individually, and can be configured as an integral sheet.

  In FIG. 3, a portion formed by the electrode 107, the piezoelectric element 105, and the electrode 106, such as a portion indicated by 21, can be regarded as one organic piezoelectric element, that is, the organic piezoelectric element 21.

  The organic piezoelectric element 21 is a receiving piezoelectric element that receives an ultrasonic signal of a reflected wave, and converts the received ultrasonic signal into an electric signal. This electrical signal is output from the electrode 106 and the electrode 107 in the organic piezoelectric element 21. This electrical signal is output to the receiver 13 via the cable 3.

  In the ultrasonic diagnostic apparatus S having such a configuration, for example, when an instruction to start diagnosis is input from the operation input unit 11, a transmission signal of an electrical signal is generated by the transmission unit 12 under the control of the control unit 16. The transmission signal of the generated electrical signal is supplied to each inorganic piezoelectric element 22 in the inorganic piezoelectric element array 4a via the cable 3.

  The electric signal transmission signal is, for example, a voltage pulse repeated at a predetermined cycle. Each of the plurality of inorganic piezoelectric elements 22 is expanded and contracted in the thickness direction by being supplied with the transmission signal of the electric signal, and is driven to ultrasonically vibrate according to the transmission signal of the electric signal.

  This ultrasonic vibration generates a first ultrasonic signal which is an ultrasonic wave, propagates through the inorganic piezoelectric element array 4b, the organic piezoelectric element array 5 and the like and is irradiated in the direction of the subject H.

  The first ultrasonic signal signal includes not only a frequency (fundamental frequency) component included in the electric signal from the transmission unit but also a harmonic component that is an integral multiple of the fundamental frequency. For example, second harmonic components such as twice, three times, and four times the fundamental frequency, third harmonic components, and fourth harmonic components are also included. This depends on the fact that the harmonic signal is included in the electrical signal itself from the transmitter and the response characteristics of the piezoelectric element.

  In the ultrasonic diagnostic apparatus, a high-definition ultrasonic image is obtained by analyzing a harmonic component in the second ultrasonic signal that is a reflected wave from the subject H. Therefore, when the harmonic component contained in the ultrasonic wave transmitted by the inorganic piezoelectric element array 4a is received by the organic piezoelectric element array 5, it becomes noise and a high-definition ultrasonic image cannot be obtained. Therefore, the inorganic piezoelectric element array 4b transmits a second ultrasonic signal that is an ultrasonic wave that cancels out the harmonic component contained in the ultrasonic wave transmitted by the inorganic piezoelectric element array 4a.

  For example, when the second harmonic is used in generating the ultrasonic image, 2 is added to the inorganic piezoelectric element array 4b so as to cancel the second harmonic contained in the ultrasonic wave transmitted by the inorganic piezoelectric element array 4a. The second harmonic is transmitted as the second ultrasonic signal.

  In addition, when the third harmonic is used when generating the ultrasonic image, as shown in FIG. 4, an inorganic piezoelectric is used so as to cancel the third harmonic included in the ultrasonic wave transmitted by the inorganic piezoelectric element array 4 a. The third harmonic is transmitted as the second ultrasonic signal to the element array 4b. In order to obtain a higher-definition ultrasonic image, it is desirable that the order be higher.

  In FIG. 4, the ultrasonic probe 2, the graph G1 showing the time waveform of the first ultrasonic signal intensity, the graph G2 showing the time waveform of the second ultrasonic signal intensity, and the first ultrasonic signal intensity and the second The graph G3 which shows the time waveform which superimposed the ultrasonic signal intensity | strength is shown. In the figure, t represents time, and AMP represents ultrasonic signal intensity.

  As shown in the graph G1, the fundamental frequency f1 and the third harmonic f3 in the time waveform of the first ultrasonic signal intensity are transmitted in phase from the surface of the inorganic piezoelectric element array 4a. The first ultrasonic signal having the fundamental frequency f1 and the third harmonic f3 travels in the direction of the subject H. In the inorganic piezoelectric element array 4b, on the surface transmitting the second ultrasonic signal from the inorganic piezoelectric element array 4b, as shown in the graph G2, the phase of the third harmonic included in the first ultrasonic signal is A third harmonic of opposite phase is transmitted. The third harmonic to be transmitted is preferably transmitted with the same amplitude as the third harmonic included in the first ultrasonic signal. As shown in the graph G3, the ultrasonic signal emitted from the ultrasonic probe 2 is obtained by superimposing the first ultrasonic signal and the second ultrasonic signal, so that the third harmonic is canceled and the fundamental wave component is obtained. And transmitted to the subject H.

  In order to cancel the third harmonic, it is desirable that the inorganic piezoelectric elements 22 that actually transmit ultrasonic waves in the inorganic piezoelectric element array 4a and the inorganic piezoelectric element array 4b are close to each other, for example, within 1 mm. An inorganic piezoelectric element 22 is disposed.

  When the third harmonic is used when generating the ultrasonic image, if both the second harmonic and the third harmonic included in the ultrasonic wave transmitted by the inorganic piezoelectric element array 4a are canceled, Further, a high-definition ultrasonic image can be obtained.

  Hereinafter, a description will be given with reference to FIG. In FIG. 5, a graph G4 showing a time waveform of the first ultrasonic signal intensity, a graph G5 showing a time waveform of the second ultrasonic signal intensity, and a time in which the first ultrasonic signal intensity and the second ultrasonic signal intensity are superimposed. The graph G6 which shows a waveform is shown. In the figure, t represents time, and AMP represents ultrasonic signal intensity.

  As shown in the graph G4, the fundamental frequency f1, the second harmonic f2, and the third harmonic f3 in the time waveform of the first ultrasonic signal intensity are transmitted in phase from the surface of the inorganic piezoelectric element array 4a (not shown). . The first ultrasonic signal having the fundamental frequency f1, the second harmonic f2, and the third harmonic f3 travels in the direction of the subject H. In the inorganic piezoelectric element array 4b, on the surface where the second ultrasonic signal is transmitted from the inorganic piezoelectric element array 4b, as shown in the graph G5, the second and third harmonics included in the first ultrasonic signal are generated. The second and third harmonics having opposite phases with respect to the respective phases are transmitted. Note that the second harmonic and the third harmonic to be transmitted are preferably transmitted with the same amplitude as the second harmonic and the third harmonic included in the first ultrasonic signal. As shown in the graph G6, the ultrasonic signal emitted from the ultrasonic probe 2 is obtained by superimposing the first ultrasonic signal and the second ultrasonic signal, so that the second harmonic and the third harmonic cancel each other. Thus, only the fundamental wave component is transmitted to the subject H.

  In addition, the intensity of each order frequency component in the first ultrasonic signal transmitted from the inorganic piezoelectric element array 4a and the inorganic piezoelectric element array 4b is input to the inorganic piezoelectric element array 4a and the inorganic piezoelectric element array 4b in advance. The relationship with electrical input is obtained by experiment. Based on the obtained data, as described above, the first ultrasonic signal and the second ultrasonic signal are superimposed, the second harmonic and the third harmonic are canceled out, and only the fundamental wave component is included. The electric input to the inorganic piezoelectric element array 4a and the inorganic piezoelectric element array 4b is controlled so as to be transmitted to the subject H. In addition, a sensor (not shown) that measures the intensity of the frequency component of each order in the first ultrasonic signal transmitted from the inorganic piezoelectric element array 4a is provided, and the frequency of each order is output from the inorganic piezoelectric element array 4b according to the measured value of the sensor. The component may be transmitted.

  As shown in FIG. 3, the first and second ultrasonic signals are stacked on the subject H by stacking the inorganic piezoelectric element array 4 a and the inorganic piezoelectric element array 4 b in the direction of the subject H. Can be stacked in the direction of. Therefore, the third harmonic can always be canceled between the ultrasound probe 2 and the subject H, and high definition is achieved regardless of the distance between the measurement location in the subject H and the ultrasound probe 2. An ultrasonic image can be constructed.

  The ultrasound probe 2 may be used in contact with the surface of the subject H, or may be inserted into the subject H, for example, inserted into a body cavity of a living body. .

  The ultrasonic wave transmitted to the subject H is reflected by one or a plurality of boundary surfaces having different acoustic impedances inside the subject H, and becomes a third ultrasonic signal that is a reflected wave of the ultrasonic wave.

  The third ultrasonic signal includes not only the frequency (fundamental fundamental frequency) component of the transmitted ultrasonic wave but also the frequency components of higher harmonics that are integer multiples of the fundamental frequency. The third ultrasonic signal is received by the ultrasonic probe 2. More specifically, the third ultrasonic signal is received by the organic piezoelectric element 21 that is a receiving piezoelectric element via the acoustic matching layer 27, and mechanical vibration is converted into an electric signal as a received signal by the organic piezoelectric element 21. Converted and taken out. The extracted reception signal is received by the receiving unit 13 controlled by the control unit 16 via the cable 3.

  The image processing unit 14 is an image of an internal state in the subject H (ultrasound image) based on the reception signal received by the reception unit 13 based on the reception signal received by the reception unit 13 from the time from transmission to reception, the reception intensity, and the like. The display unit 15 displays an image of the internal state in the subject H generated by the image processing unit 14 under the control of the control unit 16.

  Since the ultrasonic probe 2 and the ultrasonic diagnostic apparatus S in the present embodiment receive the harmonics of the fundamental wave as described above, it is possible to form an ultrasonic image by so-called harmonic imaging technology. For this reason, the ultrasonic probe 2 and the ultrasonic diagnostic apparatus S in the present embodiment can provide a higher-accuracy ultrasonic image. And since the 2nd harmonic and 3rd harmonic with comparatively big power are received, a clearer ultrasonic image can be provided.

  The ultrasonic probe 2 may be configured as shown in FIG. In the ultrasonic probe 2 shown in FIG. 6, the inorganic piezoelectric element array 4b provided in the ultrasonic probe 2 shown in FIG. 3 is not provided, and the piezoelectric element array is organic and organic piezoelectric element array 4a. Only the piezoelectric element array 5 was used.

  The ultrasonic probe 2 has a flat acoustic braking member 23, an acoustic matching layer 31 stacked on the acoustic braking member 23, an inorganic piezoelectric element array 4 a, It has the matching layer 26b, the organic piezoelectric element array 5, and the acoustic matching layer 27 laminated on the organic piezoelectric element array 5.

  The organic piezoelectric element array 5 also has a function of transmitting high-order harmonics, which is a function that the inorganic piezoelectric element array 4b has. That is, the organic piezoelectric element array 5 is a transmitting / receiving piezoelectric element having both a function of receiving the third ultrasonic signal and a function of transmitting the second ultrasonic signal.

  By using a single piezoelectric element array for transmission, a small ultrasonic probe 2 can be configured. By providing the organic piezoelectric element 21 with the function of transmitting and receiving, the high-bandwidth property at the time of reception of the organic piezoelectric element can be utilized, so that a high-definition ultrasonic image can be constructed.

  The time waveform of the first ultrasonic signal intensity, the time waveform of the second ultrasonic signal intensity, and the time waveform in which the first ultrasonic signal intensity and the second ultrasonic signal intensity are superimposed are the same as the time waveform shown in FIG. It is. Accordingly, as a result of superimposing the first ultrasonic signal and the second ultrasonic signal, the third harmonic is canceled out, and only the fundamental wave component is transmitted to the subject H.

  The ultrasonic probe 2 may be configured as shown in FIG. In FIG. 7, the inorganic piezoelectric element 22 and the organic piezoelectric element 21 are perpendicular to the direction of the subject H, the organic piezoelectric element 21-1, the inorganic piezoelectric element 22-1, the organic piezoelectric element 21-2, and the inorganic piezoelectric element 21-2. The piezoelectric elements 22-2 are alternately arranged, and the acoustic braking member 23 and the acoustic matching layer 26 are provided. Other components are omitted for simplicity.

  The inorganic piezoelectric element 22-n transmits the first ultrasonic signal, and the organic piezoelectric element 21-n transmits the second ultrasonic signal. The organic piezoelectric element 21 receives a third ultrasonic signal that is a reflected wave from the subject H.

  An ultrasonic signal transmitted by the inorganic piezoelectric element 22-n and the organic piezoelectric element 21-n will be described. In FIG. 8, a graph G7 showing a time waveform of the first ultrasonic signal intensity, a graph G8 showing a time waveform of the second ultrasonic signal intensity, and a time in which the first ultrasonic signal intensity and the second ultrasonic signal intensity are superimposed. The graph G9 which shows a waveform is shown. In the figure, t represents time, and AMP represents ultrasonic signal intensity.

  As shown in the graph G7, the fundamental frequency f1 and the third harmonic f3 in the time waveform of the first ultrasonic signal intensity are transmitted in phase from the surfaces of the inorganic piezoelectric element 22-n and the organic piezoelectric element 21-n. . For simplification of explanation, the second harmonic is ignored. The first ultrasonic signal having the fundamental frequency f1 and the third harmonic f3 travels in the direction of the subject H. In the organic piezoelectric film substrate 21-n, as shown in the graph G8, the third harmonic wave having the opposite phase to the phase of the third harmonic wave included in the first ultrasonic signal is transmitted. The third harmonic to be transmitted is preferably transmitted with the same amplitude as the third harmonic included in the first ultrasonic signal. As shown in the graph G9, the ultrasonic signal emitted from the ultrasonic probe 2 is obtained by superimposing the first ultrasonic signal and the second ultrasonic signal, so that the third harmonic is canceled and the fundamental wave component is obtained. And transmitted to the subject H.

[Circuit configuration of ultrasonic probe]
The electrical connection between the ultrasonic diagnostic apparatus and the ultrasonic probe will be described with reference to FIGS. 9 and 10 are schematic diagrams of circuit configuration examples on the transmission side and the reception side.

  First, the circuit operation during transmission will be described. Vcc is a power source having a voltage on the positive side, and Vdd is a power source having a voltage on the negative side.

  In order to drive the piezoelectric element Y1 on the transmission side 90, a transmission signal is inputted from the terminal 80 of the ultrasonic diagnostic apparatus main body 1. The transmission signal waveform may be a sine wave that is swung to the plus side or the minus side, or may be a rectangular wave. An impulse waveform may also be used.

  Since the transmission signal is a large signal, the diode D1 is turned ON and the transmission signal is applied to the piezoelectric element Y1.

  In the piezoelectric element Y2 on the reception side 91, the plus signal on the transmission waveform passes through the diode D3, then passes through the resistor R2, and flows to the Vdd side. Since the minus signal of the transmission waveform flows to the Vcc through the resistor R1 and to the Vdd side through the resistor R2, no signal is applied to the Y2 side.

  With such an operation, the piezoelectric element Y1 on the transmission side 90 can be vibrated without causing the piezoelectric element Y2 on the reception side 91 to vibrate.

  Next, the circuit operation at the time of reception will be described. In response to the second ultrasonic signal, an electric signal is generated in the piezoelectric element Y2, and the diode D3 is always turned on by Vcc and Vdd.

  The received signal passes through the diode D3 and is transmitted to the terminal 80 side. On the transmission side 90, since the diode D1 is in the OFF state due to the threshold voltage of the diode D1, no electrical signal flows to the piezoelectric element Y1 side. With the above operation, the circuit shown in FIG. 9 has a function of a transmission / reception switching circuit even if a switch is not used.

  Further, a circuit having the configuration shown in FIG. 10 may be used. First, the circuit operation during transmission will be described. Vcc is a power source having a voltage on the positive side, and Vdd is a power source having a voltage on the negative side.

  In order to drive the piezoelectric element Y1 on the transmission side 90, a transmission signal is inputted from the terminal 80 of the ultrasonic diagnostic apparatus main body 1. The transmission signal waveform may be a sine wave that is swung to the plus side or the minus side, or may be a rectangular wave. An impulse waveform may also be used.

  Since the transmission signal is a large signal, the diode D1 is turned ON and the transmission signal is applied to the piezoelectric element Y1.

  In the piezoelectric element Y2 on the receiving side 91, since the diodes D17, D18, D19, and D20 are always turned on by the voltages of Vcc and Vdd, the positive signal of the transmission waveform passes through the resistor R12 and then goes to the Vcc side. Flowing. Since the negative signal of the transmission waveform flows to the Vdd side through the resistor R14, no signal is applied to the Y2 side.

  By such an operation, it is possible to vibrate the piezoelectric element Y1 on the transmission side 90 without vibrating the signal Y2 on the reception side 91.

  Next, the circuit operation at the time of reception will be described. Upon receipt of the second ultrasonic signal, an electric signal is generated from Y2, and the operational amplifier U amplifies the electric signal according to an amplification factor determined by the ratio of the resistors R10, R11, and R13. When the second ultrasonic signal is not amplified, the second ultrasonic signal is directly connected between the diode D17 and the diode D19. The diodes D17 and D19 are always turned on by Vcc and Vdd.

  Since the same voltage is generated between the diode D17 and the diode D19 connected to the terminal 80 side, the electrical signal transmitted between the diode D17 and the diode D19 is transmitted to the terminal 80 of the ultrasonic diagnostic apparatus main body 1.

  Since the diode D16 is in the OFF state due to the threshold voltage of the diode D16, the reception signal does not flow to the piezoelectric element Y1 side of the transmission side 90. Through the above operation, the circuit shown in FIG. 10 has a function of a transmission / reception switching circuit even if a switch is not used.

  Note that the diodes D17, D18, D19, and D20 are always turned off by making the Vcc and Vdd voltages reverse when transmitting (Vcc is the negative side and Vdd is the positive side), so the transmission signal is completely It is possible not to flow to the resistor R13 side.

[Self-check function and setup function of ultrasonic probe]
The self-check function of the ultrasonic probe in this embodiment will be described below with reference to FIGS. FIG. 11 is a flowchart of the self-check function process.

  The self-checking function of the ultrasonic probe cancels the higher harmonics included in the first ultrasonic signal transmitted by the first transmitting piezoelectric element with the higher harmonics transmitted to the second transmitting piezoelectric element. This is a function of self-checking whether or not high-order harmonics included in the ultrasonic wave emitted from the ultrasonic probe 2 are reduced to a degree satisfying a predetermined standard as a result of performing the operation.

  The ultrasonic probe setup function is the second transmission piezoelectric when the high-order harmonics contained in the ultrasonic wave emitted from the ultrasonic probe 2 are not reduced to a degree satisfying a predetermined standard. This is a function to reduce the high-order harmonics included in the ultrasonic wave emitted from the ultrasonic probe 2 to a degree satisfying a predetermined standard by changing the output of the high-order harmonics to be transmitted to the element.

  The following operations are performed mainly by the control unit 16, and the operation timing may be performed in response to an operation instruction input from the operator, or the ultrasonic diagnostic apparatus is started up. May be performed automatically. The ultrasonic probe 2 is premised on the one shown in FIG. 3, but may be another ultrasonic probe 2 shown in FIGS. For simplification of explanation, the higher order harmonic is only the third order harmonic, and the second order harmonic is ignored.

  First, in step S1, the control unit 16 causes the transmission unit 12 to drive one inorganic piezoelectric element 22a in the inorganic piezoelectric element array 4a that is the first transmission piezoelectric element to transmit a first ultrasonic signal. . Then, in the inorganic piezoelectric element array 4b which is the second transmitting piezoelectric element, the inorganic piezoelectric element 22b existing in the vicinity of the subject H direction of the driven inorganic piezoelectric element 22a is driven to transmit the second ultrasonic signal. Let The driving of the inorganic piezoelectric element 22a and the inorganic piezoelectric element 22b is performed at a timing that cancels out the third harmonic as described above.

  Next, in step S2, the first ultrasonic signal and the second ultrasonic signal are present in the vicinity of the transmitted inorganic piezoelectric element 22a and the inorganic piezoelectric element 22b in the organic piezoelectric element array 5 that is a receiving piezoelectric element. The signal is received by the organic piezoelectric element 21.

  Next, in step S <b> 3, the check unit 17 performs frequency analysis of the electrical signal generated by combining the first ultrasonic signal and the second ultrasonic signal received by the organic piezoelectric element 21. If the third harmonic in the first ultrasonic signal is canceled out by the second ultrasonic signal, the third harmonic can be hardly observed in the electric signal output from the organic piezoelectric element 21. Actually, the determination is made based on whether or not the amplitude of the third harmonic is below a predetermined reference value. For example, the predetermined reference value is set to a value that is negligibly small compared to the third harmonic generated by reflecting the first ultrasonic signal at the subject H.

  As a method of frequency analysis, a method of applying a filter such as FFT (Fast Fourier transform) and FIR (Finite impulse response) is adopted. By the frequency analysis, the signal amplitude can be calculated for each frequency included in the ultrasonic wave in which the first ultrasonic signal and the second ultrasonic signal are combined. For example, an analysis result as shown in FIG. 12 can be obtained. FIG. 12 is a schematic diagram showing a frequency spectrum of an ultrasonic wave in which the first ultrasonic signal and the second ultrasonic signal are combined.

  In FIG. 12, the existence of a fundamental frequency f1 having a signal amplitude value p1, a second harmonic frequency f2 having a signal amplitude value p2, and a third harmonic frequency f3 having a signal amplitude value p3 is confirmed.

  Next, in step S4, when the reference value is pc, the check unit 17 performs a self-check to determine whether the amplitude value of the third harmonic is below the reference value, that is, p3 <pc. .

  If the amplitude value of the third harmonic is not lower than the reference value, the process proceeds to step S5, and the control unit 16 sets the transmission condition of the inorganic piezoelectric element array 4b so that the amplitude value of the third harmonic is lower than the reference value. Perform the setup to be adjusted. After the adjustment, the process proceeds to step S1, and similarly, the first transmission piezoelectric element and the second transmission piezoelectric element are driven. The adjustment result is stored in the storage unit 18 and used for future operations. Note that it is preferable to continue the setup until the amplitude value of the third harmonic falls below the reference value.

  If the amplitude value of the third harmonic is below the reference value, the process proceeds to step S6, and the same processing is performed on the next inorganic piezoelectric element 22a, inorganic piezoelectric element 22b, and organic piezoelectric element array 5.

  In step S6, when all the inorganic piezoelectric elements 22a and the inorganic piezoelectric elements 22b are processed, the flow ends.

  When the ultrasonic probe 2 shown in FIG. 6 is used, the first ultrasonic signal is transmitted to the inorganic piezoelectric element 22, the second ultrasonic signal is transmitted to the organic piezoelectric element 21, and the first ultrasonic signal is transmitted. The ultrasonic wave combined with the sound wave signal and the second ultrasonic probe is received by, for example, the organic piezoelectric element 21 in the vicinity of the organic piezoelectric element 21 that transmits the second ultrasonic signal. Even when the ultrasonic probe 2 shown in FIG. 7 is used, reception is performed by the organic piezoelectric element 21 in the vicinity of the organic piezoelectric element 21-n that transmits the second ultrasonic signal, for example, the organic piezoelectric element 21- (n + 1). To do.

  As described above, according to the present embodiment, the first ultrasonic signal transmitted by the first transmitting piezoelectric element is included in the second transmitting piezoelectric element disposed in the vicinity of each first transmitting piezoelectric element. It is included in the first ultrasonic signal by transmitting a second ultrasonic signal having an opposite phase to at least one harmonic component of a predetermined order and performing self-check and setup using the receiving piezoelectric element. High-order harmonics can be canceled out, and a high-definition ultrasonic image can be constructed.

  In addition, according to the present embodiment, a high-definition ultrasonic image can be constructed with a small configuration by using both the second transmitting piezoelectric element and the receiving piezoelectric element. Furthermore, by providing the organic piezoelectric element 21 with the function of transmitting and receiving, the high-bandwidth property at the time of reception of the organic piezoelectric element can be utilized, so that a high-definition ultrasonic image can be constructed.

  In addition, according to the present embodiment, the inorganic piezoelectric elements 22 that transmit ultrasonic waves in the inorganic piezoelectric element array 4a and the inorganic piezoelectric element array 4b are arranged close to each other within 1 mm, thereby effectively providing the third. Harmonics can be canceled out.

  Further, according to the present embodiment, higher harmonic components among the harmonic components included in the first ultrasonic signal transmitted from the first transmitting piezoelectric element to the second transmitting piezoelectric element are converted. On the other hand, a second ultrasonic signal having an opposite phase is transmitted, and a self-check and setup are performed using the receiving piezoelectric element, whereby a higher-definition ultrasonic image can be obtained.

  Further, according to the present embodiment, the first ultrasonic signal and the second ultrasonic signal are obtained by stacking the inorganic piezoelectric element array 4a and the inorganic piezoelectric element array 4b in the direction of the subject H. It can be overlaid in the direction of H. Therefore, the third harmonic component can always be canceled between the ultrasound probe 2 and the subject H, and the high frequency is obtained regardless of the distance between the measurement location in the subject H and the ultrasound probe 2. A fine ultrasonic image can be constructed.

DESCRIPTION OF SYMBOLS 1 Ultrasonic diagnostic apparatus main body 2 Ultrasonic probe 3 Cable 4 Inorganic piezoelectric element array 5 Organic piezoelectric element array 11 Operation input part 12 Transmission part 13 Reception part 14 Image processing part 15 Display part 16 Control part 17 Check part 18 Storage part DESCRIPTION OF SYMBOLS 21 Organic piezoelectric element 22 Inorganic piezoelectric element 24 Acoustic separation part 25 Common ground electrode 26, 27, 31 Acoustic matching layer 51 Organic piezoelectric element array 80 Terminal 101 Piezoelectric element 102, 103, 106, 107 Electrode 105 Piezoelectric element H Subject S Super Sonic diagnostic equipment

Claims (8)

A plurality of first transmitting piezoelectric elements for transmitting a first ultrasonic signal into the subject;
A second layer opposite to the at least one harmonic component of a predetermined order included in the first ultrasonic signal transmitted from the first transmitting piezoelectric element and disposed on the first transmitting piezoelectric element. A plurality of second transmitting piezoelectric elements for transmitting ultrasonic signals;
Wherein Ri first ultrasonic signal and the second reflected wave der generated by reflected ultrasonic waves and the ultrasonic signal is superimposed in the inside of the subject, a third greater than that contains a harmonic component of the predetermined order A plurality of receiving piezoelectric elements that receive sound wave signals and convert them into electrical signals;
An ultrasonic probe comprising:
A transmitter for driving the first transmitting piezoelectric element and the second transmitting piezoelectric element;
A receiver for driving the receiving piezoelectric element;
An image processing unit for generating an ultrasound image in the subject from the electrical signal;
An ultrasonic diagnostic apparatus comprising:   The ultrasonic diagnostic apparatus according to claim 1, wherein the second transmitting piezoelectric element is disposed at a distance of 1 mm or less from the first transmitting piezoelectric element.   The ultrasonic diagnostic apparatus according to claim 1, wherein the reception piezoelectric element is disposed so as to be stacked on the second transmission piezoelectric element. The first transmitting piezoelectric element and the second transmitting piezoelectric element are inorganic piezoelectric elements,
The ultrasonic diagnostic apparatus according to claim 3, wherein the receiving piezoelectric element is an organic piezoelectric element.   The ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic probe includes a transmission / reception piezoelectric element having both functions of the second transmission piezoelectric element and the reception piezoelectric element. The transmitting and receiving piezoelectric element, ultrasonic diagnostic apparatus according to claim 5, characterized in that it is disposed from the first transmitting piezoelectric element within a distance of 1 mm. The first transmitting piezoelectric element is an inorganic piezoelectric element,
The ultrasonic diagnostic apparatus according to claim 5, wherein the transmitting / receiving piezoelectric element is an organic piezoelectric element.   The ultrasonic diagnostic apparatus according to claim 1, wherein the predetermined order is a second order or a third order.

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