JP7293104B2 - Ultrasound diagnostic equipment and ultrasound probe - Google Patents

Description

The embodiments disclosed in the specification and drawings relate to an ultrasonic diagnostic apparatus and an ultrasonic probe.

An ultrasonic diagnostic apparatus radiates ultrasonic waves to a subject using, for example, an ultrasonic probe equipped with a sensor device such as an ultrasonic transducer, and receives reflected waves of the radiated ultrasonic waves by the ultrasonic probe. to generate ultrasound images.

When an electric signal generated by a sensor device receiving a reflected wave is received by the reception circuit front end, the impedance of the reception circuit front end is set to , is preferably the complex conjugate of the impedance of the sensor device. However, if an attempt is made to faithfully realize the frequency characteristics of the sensor device using general-purpose electric elements (eg, resistors, inductors, capacitors, etc.), the circuit configuration becomes complicated and the circuit scale becomes enormous. Therefore, the circuit configuration of the reception front end is not strictly a configuration for impedance matching with the sensor device, which may be a factor in impairing the reception performance.

JP 2018-175492 A

One of the problems to be solved by the embodiments disclosed in the specification and drawings is to match the impedance of the receiving front-end circuit with the impedance of the sensor device. However, the problems to be solved by the embodiments disclosed in this specification and drawings are not limited to the above problems. A problem corresponding to each effect of each configuration shown in the embodiments described later can be positioned as another problem.

An ultrasonic diagnostic apparatus according to an embodiment includes a sensor device and a receiver. The sensor device has at least one ultrasonic transducer that generates ultrasonic waves based on a drive signal, receives reflected wave signals of the ultrasonic waves, and converts them into electrical signals. The receiving means has an ultrasonic transducer corresponding to the ultrasonic transducer of the sensor device as a matching element for matching impedance with the sensor device, and receives the electrical signal.

FIG. 1 is a block diagram showing the functional configuration of an ultrasonic diagnostic apparatus according to the first embodiment. FIG. 2 is a diagram showing the front-end configuration of the ultrasonic receiving circuit shown in FIG. FIG. 3 is a diagram showing a front-end configuration of a conventional ultrasonic wave receiving circuit. FIG. 4 is a block diagram showing the functional configuration of an ultrasonic diagnostic apparatus according to a modification of the first embodiment; FIG. 5 is a diagram showing the front-end configuration of the receiving circuit shown in FIG. FIG. 6 is a diagram showing configurations of a sensor device, a DC voltage source, and a transmission drive circuit/reception detection circuit in an ultrasonic probe according to the second embodiment. FIG. 7 is a diagram showing a front-end configuration of a conventional transmission drive circuit/reception detection circuit.

Embodiments will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing an example of the functional configuration of an ultrasonic diagnostic apparatus 1 according to the first embodiment. An ultrasonic diagnostic apparatus 1 shown in FIG. 1 has an apparatus body 10 and an ultrasonic probe 20 . The device body 10 and the ultrasonic probe 20 are connected via a cable, for example. The device body 10 is connected to the input device 30 and the display device 40 . Further, the device body 10 is connected to an external device 50 via a network NW.

The ultrasonic probe 20 performs an ultrasonic scan on a scan region within the living body P, which is the subject, under control from the apparatus main body 10, for example. The ultrasonic probe 20 includes, for example, a plurality of ultrasonic transducers as the sensor device 21, a matching layer provided on the ultrasonic transducers, and a backing material for preventing ultrasonic waves from propagating backward from the ultrasonic transducers. have. The ultrasonic transducer generates ultrasonic waves based on a drive signal, receives a reflected ultrasonic wave signal, and converts it into an electric signal. The ultrasonic vibrator is, for example, a piezoelectric vibrator, and is made of piezoelectric ceramic as an example. The ultrasonic probe 20 is detachably connected to the device body 10 . The ultrasonic probe 20 may be provided with buttons that are pressed during offset processing, freezing of ultrasonic images, and the like.

The ultrasonic probe 20 is, for example, a 1D array linear probe in which a plurality of ultrasonic transducers are arranged along a predetermined direction, a 2D array probe in which a plurality of ultrasonic transducers are arranged in a matrix, or an ultrasonic vibration probe. It is a mechanical 4D probe or the like that can perform ultrasonic scanning while mechanically tilting the child row in a direction orthogonal to the arrangement direction.

The plurality of ultrasonic transducers generate ultrasonic waves based on drive signals supplied from an ultrasonic transmission circuit 11 (described later) of the device main body 10 . As a result, ultrasonic waves are transmitted from the ultrasonic probe 20 to the living body P. FIG. When ultrasonic waves are transmitted from the ultrasonic probe 20 to the living body P, the transmitted ultrasonic waves are successively reflected by discontinuous surfaces of acoustic impedance in the body tissue of the living body P, and a plurality of ultrasonic vibrations are generated as reflected wave signals. Received by the child. The amplitude of the received reflected wave signal depends on the difference in acoustic impedance at the discontinuity from which the ultrasonic waves are reflected. In addition, when a transmitted ultrasonic pulse is reflected by a moving blood flow or a surface such as a heart wall, the reflected wave signal depends on the velocity component in the ultrasonic transmission direction of the moving object due to the Doppler effect. subject to frequency shifts. The ultrasonic transducer receives a reflected wave signal from the living body P and converts it into an electrical signal.

Note that FIG. 1 illustrates only the connection relationship between the ultrasonic probe 20 used for ultrasonic scanning and the device main body 10 . However, it is possible to connect a plurality of ultrasonic probes to the device body 10 . It is possible to arbitrarily select one of the connected ultrasonic probes to be used for ultrasonic scanning by a switching operation.

The device main body 10 is a device that generates an ultrasonic image based on reflected wave signals received by the ultrasonic probe 20 . The apparatus main body 10 has an ultrasonic transmission circuit 11 , an ultrasonic reception circuit 12 , an internal storage circuit 13 , an image memory 14 , an input interface 15 , an output interface 16 , a communication interface 17 and a processing circuit 18 .

The ultrasonic transmission circuit 11 is a processor that supplies drive signals to the ultrasonic probe 20 . The ultrasonic transmission circuit 11 is realized by a pulse generator 111, a transmission delay circuit 112, and a pulser circuit 113, for example. The pulse generator 111 repeatedly generates driving trigger pulses for forming transmission ultrasonic waves at a predetermined repetition frequency (PRF: Pulse Repetition Frequency). In the transmission delay circuit 112, the pulse generator 111 generates a delay time for each ultrasonic transducer necessary for focusing the ultrasonic waves generated from the ultrasonic probe 20 into a beam and determining the transmission directivity. given for each drive trigger pulse. The transmission direction or the transmission delay time that determines the transmission direction is stored in the internal storage circuit 13 and referred to during transmission. The pulsar circuit 113 applies drive signals (drive pulses) to the plurality of ultrasonic transducers provided in the ultrasonic probe 20 at timings based on the drive trigger pulses. By changing the delay time given to each drive trigger pulse by the transmission delay circuit 112, the transmission direction from the ultrasonic transducer surface can be arbitrarily adjusted.

The ultrasonic wave receiving circuit 12 is a processor that performs various processing on the reflected wave signal received by the ultrasonic probe 20 and generates a received signal. The ultrasonic wave receiving circuit 12 is implemented by a preamplifier 121, an A/D converter 122, a demodulator 123, and a beamformer 124, for example. The preamplifier 121 amplifies the reflected wave signal received by the ultrasonic probe 20 for each channel and performs gain correction processing. In this embodiment, an example in which the preamplifier 121 serves as the front end of the ultrasonic wave receiving circuit 12 will be described, but the front end of the ultrasonic wave receiving circuit 12 is not limited to the preamplifier 121 . The A/D converter 122 converts the gain-corrected reflected wave signal into a digital signal. The demodulator 123 demodulates the digital signal to convert the digital signal into a baseband in-phase signal (I signal, I: In-phase) and a quadrature signal (Q signal, Q: Quadrature-phase). . The beamformer 124 gives the I signal and the Q signal (hereinafter referred to as IQ signal) a delay time necessary to determine the reception directivity. The beamformer 124 adds the IQ signals given the delay time. Processing by the beamformer 124 generates a received signal in which the reflection component from the direction corresponding to the reception directivity is emphasized.

The internal storage circuit 13 has, for example, a magnetic or optical storage medium, or a processor-readable storage medium such as a semiconductor memory. The internal storage circuit 13 stores, for example, a program for realizing ultrasonic wave transmission/reception. The internal storage circuit 13 stores diagnostic information, scan sequences, diagnostic protocols, ultrasonic transmission/reception conditions, signal processing conditions, image generation conditions, image processing conditions, body mark generation programs, display conditions, and color data used for visualization. Various data such as a conversion table for presetting a range for each diagnostic site are stored. Programs and various data may be stored in advance in the internal storage circuit 13, for example. Alternatively, for example, it may be stored in a non-transitory storage medium, distributed, read out from the non-transitory storage medium, and installed in the internal storage circuit 13 .

The internal storage circuit 13 also stores received signals generated by the ultrasonic receiving circuit 12 and various ultrasonic image data generated by the processing circuit 18 in accordance with operations input via the input interface 15 . The internal storage circuit 13 can also transfer stored data to the external device 50 or the like via the communication interface 17 .

The internal storage circuit 13 may be a drive device or the like that reads and writes various information from/to a portable storage medium such as a CD-ROM drive, a DVD drive, and a flash memory. The internal storage circuit 13 can also write the stored data to a portable storage medium and store the data in the external device 50 via the portable storage medium.

The image memory 14 has, for example, a magnetic storage medium, an optical storage medium, or a processor-readable storage medium such as a semiconductor memory. The image memory 14 stores image data corresponding to a plurality of frames immediately before the freeze operation input via the input interface 15 . The image data stored in the image memory 14 are, for example, continuously displayed (cine display).

The internal storage circuit 13 and the image memory 14 do not necessarily have to be realized by independent storage devices. The internal storage circuit 13 and image memory 14 may be realized by a single storage device. Also, each of the internal storage circuit 13 and the image memory 14 may be realized by a plurality of storage devices.

The input interface 15 receives various instructions from the operator via the input device 30 . The input device 30 is, for example, a mouse, keyboard, panel switch, slider switch, trackball, rotary encoder, operation panel, and touch command screen (TCS). The input interface 15 is connected to the processing circuit 18 via, for example, a bus, converts an operation instruction input by an operator into an electrical signal, and outputs the electrical signal to the processing circuit 18 . It should be noted that the input interface 15 is not limited to being connected to physical operation components such as a mouse and keyboard. For example, a circuit that receives an electrical signal corresponding to an operation instruction input from an external input device provided separately from the ultrasonic diagnostic apparatus 1 and outputs this electrical signal to the processing circuit 18 is also an example of an input interface. included.

The output interface 16 is, for example, an interface for outputting electrical signals from the processing circuit 18 to the display device 40 . The display device 40 is any display such as a liquid crystal display, an organic EL display, an LED display, a plasma display, a CRT display, or the like. The output interface 16 is connected to the processing circuit 18 via, for example, a bus, and outputs electrical signals from the processing circuit 18 to the display device.

The communication interface 17 is connected to the external device 50 via the network NW, for example, and performs data communication with the external device 50 .

The processing circuit 18 is, for example, a processor that functions as the core of the ultrasonic diagnostic apparatus 1 . The processing circuit 18 executes a program stored in the internal storage circuit 13 to implement functions corresponding to the program. The processing circuit 18 has a B-mode processing function 181, a Doppler processing function 182, an image generation function 183, a display control function 184, and a system control function 185, for example. In this embodiment, a case where a single processor realizes the B-mode processing function 181, the Doppler processing function 182, the image generation function 183, the display control function 184, and the system control function 185 will be described. Not limited. For example, a processing circuit is configured by combining a plurality of independent processors, and each processor executes a program to perform a B-mode processing function 181, a Doppler processing function 182, an image generation function 183, a display control function 184, and a system control function. 185 may be realized. Also, a dedicated hardware circuit capable of executing each function may be incorporated.

The B-mode processing function 181 is a function of generating B-mode data based on the received signal received from the ultrasonic wave receiving circuit 12 . Specifically, in the B-mode processing function 181, the processing circuit 18 performs, for example, envelope detection processing, logarithmic compression processing, etc. on the received signal received from the ultrasonic wave receiving circuit 12, and the signal strength is reduced to the luminance brightness level. Data (B-mode data) represented by the depth is generated. The generated B-mode data is stored in a RAW data memory (not shown) as B-mode RAW data on two-dimensional ultrasound scanning lines (raster).

The Doppler processing function 182 frequency-analyzes the received signal received from the ultrasound receiving circuit 12 to perform blood flow analysis based on the Doppler effect of a mobile object within an imaging ROI (Region Of Interest) set in the scan area. This is a function to generate data (Doppler data) related to flow information. Blood flow information includes mean velocity, variance, power, or a combination thereof of blood flow in the subject. The generated Doppler data is stored in a RAW data memory (not shown) as Doppler RAW data on two-dimensional ultrasound scanning lines.

The image generation function 183 is a function for generating various ultrasonic image data based on data generated by the B-mode processing function 181 and/or the Doppler processing function 182 . Specifically, in the image generation function 183, the processing circuit 18 performs, for example, RAW-pixel conversion on the B-mode RAW data stored in the RAW data memory, for example, the scanning form of ultrasound by the ultrasound probe 20. B-mode image data composed of pixels is generated by performing the corresponding coordinate transformation.

Further, the processing circuit 18 generates Doppler image data in which blood flow information is visualized, for example, by performing RAW-pixel conversion on the Doppler RAW data stored in the RAW data memory. Doppler image data is mean velocity image data, variance image data, power image data, or image data combining these.

The display control function 184 is a function for causing the display device 40 to display an image based on various ultrasonic image data generated by the image generation function 183 . Specifically, for example, in the display control function 184, the processing circuit 18 controls the image on the display device 40 based on the image data including the B-mode image data, the Doppler image data, or both generated by the image generation function 183. Control display.

In the display control function 184, the processing circuit 18, for example, converts (scan converts) a scanning line signal train of ultrasonic scanning into a scanning line signal train of a video format typified by television, etc., and generates image data for display. . Further, the processing circuit 18 may perform various kinds of processing such as dynamic range, luminance (brightness), contrast, γ curve correction, and RGB conversion on the image data for display. Further, the processing circuit 18 may add supplementary information such as character information of various parameters, scales, and body marks to the display image data. The processing circuit 18 may also generate a user interface (GUI: Graphical User Interface) for the operator to input various instructions using an input device, and display the GUI on the display device 40 .

The system control function 185 is a function for controlling basic operations such as input/output of the ultrasonic diagnostic apparatus 1 and transmission/reception of ultrasonic waves.

Next, the configuration of the front end of the ultrasonic wave receiving circuit 12 shown in FIG. 1 will be described in detail.
FIG. 2 is a schematic diagram showing a configuration example of the front end of the ultrasonic wave receiving circuit 12 shown in FIG. In FIG. 2, the ultrasonic probe 20 has a plurality of sensor devices 21, for example, two ultrasonic transducers 211-1 and 211-2 connected in parallel. In the example shown in FIG. 2, the sensor device 21 is connected to part of the preamplifier 121 via a first capacitor 125 provided in the ultrasound receiving circuit 12 . The number of ultrasonic transducers forming the sensor device 21 is not limited to two, and may be one or three or more.

The preamplifier 121 shown in FIG. 2 has an LNA (Low Noise Amplifier) 1211 and a feedback element 1212, for example. It should be noted that the LNA 1211 is followed by, for example, a further amplifier, not shown, also as part of the preamplifier 121 . Although not shown in FIG. 2, the LNA 1211, the feedback element 1212, and the first to third capacitors 125-127 are provided for each sensor device 21, for example.

The LNA 1211 is connected with the sensor device 21 via the first capacitor 125, which is a coupling capacitor. Also, the LNA 1211 is grounded via a second capacitor 126, which is a bypass capacitor. LNA 1211 amplifies the amplitude of the input signal provided through first capacitor 125 . The LNA 1211 outputs the first signal whose amplitude is amplified and the second signal obtained by inverting the first signal to the subsequent stage. Part of the second signal is supplied to the first capacitor 125 via the feedback element 1212 provided on the feedback route and the third capacitor 127 .

The feedback element 1212 is the same element as the ultrasonic transducers 211-1 and 211-2. That is, the impedance of feedback element 1212 is equal to the impedance of ultrasonic transducers 211-1 and 211-2. In FIG. 2, one feedback element 1212 is provided for the ultrasonic transducers 211-1 and 211-2 constituting the sensor device 21 so that the LNA 1211 doubles the amplitude of the input signal. . Note that the number of feedback elements 1212 provided in the feedback route is not limited to one. The number of feedback elements 1212 may be adjusted according to the degree of amplification by the LNA 1211 and the number of ultrasonic transducers forming the sensor device 21 .

Next, amplification of received signals by the LNA 1211 will be described.
The impedance _Zxdcr of the sensor device 21 shown in FIG. 2 is
_Zxdcr = _Zx / _Nt (1)
is represented. _Zx represents the impedance of one ultrasonic transducer that constitutes the sensor device 21, and _Nt represents the number of parallel ultrasonic transducers that constitute the sensor device 21. FIG.

The input impedance _Zr of LNA 1211 shown in FIG.
_Zr = _Zx /(1+ _AVLNA /2) (2)
is represented. Z _x represents the impedance of feedback element 1212 and A _VLNA represents the gain of LNA 1211 .

The output voltage _Eout of the LNA 1211 is obtained from the input impedance _Zr of the LNA 1211 and the impedance _Zxdcr of the sensor device 21, for example, as follows.

_Eout =( _Zr / _Zxdcr )* _Ein (3)
Substituting equations (1) and (2) into equation (3) yields
_Eout = (( _Zx /(1+ _AVLNA /2))/( _Zx / _Nt )) x _Ein
=( _Nt /(1+ _AVLNA /2))* _Ein (4)
As a result, the impedance Z _x of the ultrasonic transducer is no longer included in the voltage amplification factor of the LNA unit system: N _t /(1+A _VLNA /2). That is, according to the equation (4), the signal output from the LNA 1211 is no longer affected by the impedance _Zx of the ultrasonic transducer.

Next, a front end of a conventional ultrasonic wave receiving circuit will be described for comparison with the front end of the ultrasonic wave receiving circuit 12 according to the first embodiment. FIG. 3 is a schematic diagram showing a configuration example of a front end of a conventional ultrasonic receiving circuit. The preamp shown in FIG. 3 has a configuration in which the LNA performs active termination. That is, a feedback route is formed in the LNA, and the formed feedback route is provided with a variable resistor.

If the impedance of the variable resistor is _Rf , the impedance _Zr of the LNA shown in FIG. 3 is
_Zr = _Rf /(1+ _AVLNA /2) (5)
is represented. Then, the output voltage of the LNA shown in FIG. 3 is obtained as follows from equations (1), (3), and (5).

_Eout =(( _Rf * _Nt )/( _Zx *(1+ _AVLNA /2)))* _Ein (6)
In this way, the impedance Z _x of the ultrasonic transducer remains in the system voltage amplification factor: (R _f ×N _t )/(Z _x ×(1+A _VLNA /2)). That is, according to equation (6), the signal output from the LNA shown in FIG. 3 is affected by the impedance _Zx of the ultrasonic transducer. Therefore, the frequency band of the received signal may be restricted.

As described above, in the first embodiment, the sensor device 21 includes at least one ultrasonic transducer that generates ultrasonic waves based on drive signals, receives reflected ultrasonic wave signals, and converts them into electrical signals. 211. The ultrasonic receiving circuit 12 amplifies an electric signal with an NLA 1211 as a front end, and feeds back part of the amplified signal through a loop in which a matching element (feedback element) 1212 having the same configuration as the ultrasonic transducer 211 is arranged. I have to. As a result, the configuration of the front end of the ultrasonic wave receiving circuit 12 as receiving means corresponds to the electrical characteristics of the sensor device 21 .

(Modification)
In the first embodiment, the case where the feedback element 1212 is provided in the ultrasonic receiving circuit 12 as the front end has been described as an example. However, the site where the feedback element 1212 is provided is not limited to the ultrasonic wave receiving circuit 12 of the device body 10 . If the receive LNA circuit is provided in the ultrasound probe, a feedback element may be provided in the receive LNA circuit within the ultrasound probe.

FIG. 4 is a block diagram showing an example of the functional configuration of an ultrasonic diagnostic apparatus 1a according to a modification of the first embodiment. The ultrasonic diagnostic apparatus 1a shown in FIG. 4 has an apparatus body 10a and an ultrasonic probe 20a. The device body 10a and the ultrasonic probe 20a are connected via a cable, for example.

The device main body 10a is a device that generates an ultrasonic image based on reflected wave signals received by the ultrasonic probe 20a. The apparatus main body 10a has an ultrasonic transmission circuit 11a, an ultrasonic reception circuit 12a, an internal storage circuit 13, an image memory 14, an input interface 15, an output interface 16, a communication interface 17, and a processing circuit .

For example, the ultrasonic probe 20a performs an ultrasonic scan on a scan region within a living body P, which is a subject, under control from the apparatus main body 10a. The ultrasonic probe 20a includes, for example, a plurality of ultrasonic transducers as the sensor device 21, a matching layer provided on the ultrasonic transducers, and a backing material for preventing ultrasonic waves from propagating backward from the ultrasonic transducers. have. The ultrasonic probe 20a also has a transmission circuit 22a as a processor that supplies drive signals to the sensor device 21, and a reception circuit 23a as a processor that performs various processing on the reflected wave signal received by the sensor device 21. . The number of transmission circuits 22a and reception circuits 23a corresponding to the number of sensor devices 21, for example, is provided.

FIG. 5 is a schematic diagram showing a configuration example of the front end of the receiving circuit 23a in the ultrasonic probe shown in FIG. In FIG. 5, the ultrasonic probe 20a has a plurality of sensor devices 21, for example, two ultrasonic transducers 211-1 and 211-2 connected in parallel. In the example shown in FIG. 5, the sensor device 21 is connected through a first capacitor 232 to part of the preamplifier 231 provided in the receiving circuit 23a. The number of ultrasonic transducers forming the sensor device 21 is not limited to two, and may be one or three or more.

The preamplifier 231 shown in FIG. 5 has, for example, an LNA 2311 and a feedback element 2312 . It should be noted that the LNA 2311 is followed by, for example, a further amplifier not shown, also as part of the preamplifier 231 .

LNA 2311 and feedback element 2312 are similar to LNA 1211 and feedback element 1212 described in FIG. By providing the feedback element 2312 in the feedback route of the LNA 2311, the signal output from the LNA 2311 is not affected by the impedance _Zx of the ultrasonic transducer.

(Second embodiment)
In the first embodiment, the case where the sensor device 21 is composed of an ultrasonic transducer has been described as an example. In the second embodiment, a case where the sensor device is composed of a CMUT (Capacitive Micromachined Ultrasound Transducer), which is a capacitive ultrasonic transducer, will be described. A CMUT is an example of an ultrasonic transducer that generates an ultrasonic wave based on a drive signal, receives a reflected wave signal of the ultrasonic wave, and converts it into an electric signal. PMUTs (Piezoelectric Micromachined Ultrasound Transducers) may be used instead of CMUTs.

The ultrasonic probe 20b according to the second embodiment, for example, executes an ultrasonic scan of a scan region within a living body P, which is a subject, under control from the apparatus main body. The ultrasonic probe 20b includes, for example, a sensor device 21b, a DC voltage source 24b, and a transmission drive circuit/reception detection circuit 25b.

FIG. 6 is a schematic diagram showing a configuration example of the sensor device 21b, the DC voltage source 24b, and the transmission drive circuit/reception detection circuit 25b in the ultrasonic probe 20b according to the second embodiment. The sensor device 21b shown in FIG. 6 is configured using, for example, a CMUT formed by a MEMS (Micro Electro Mechanical Systems) process.

The left diagram of FIG. 6 represents a schematic cross-sectional diagram of the sensor device 21b. In FIG. 6, a first insulating film 213 is arranged on a substrate 212 made of silicon or the like, and a first electrode 214 is formed on the first insulating film 213 . If the substrate 212 is an insulating substrate such as a glass substrate, the first insulating film 213 is unnecessary. A second insulating film 215 is arranged on the first electrode 214 , and a plurality of vibrating film portions 216 having gaps are formed on the second insulating film 215 . A second electrode 217 is formed on the vibration film portion 216 . In this embodiment, a set of the substrate 212, the first insulating film 213, the first electrode 214, the second insulating film 215, the vibrating film portion 216, and the second electrode 217 is called a cell. The ultrasonic probe 20b has a plurality of sensor devices 21b, and each sensor device 21b is composed of five cells, for example, as shown in FIG. The DC voltage source 24b and the transmission drive circuit/reception detection circuit 25b are connected to the sensor devices 21b, transmit ultrasonic waves for each sensor device 21b, and receive reflected ultrasonic wave signals for each sensor device 21b.

A DC voltage source 24b is connected to the first electrode 214 of the sensor device 21b, and a transmission drive circuit/reception detection circuit 25b is connected to the second electrode 217 of the sensor device 21b. A predetermined potential difference is generated between the first electrode 214 and the second electrode 217 by the DC voltage source 24b.

The transmission drive circuit/reception detection circuit 25 b includes a current-voltage conversion circuit 251 , protection switches 252 and 253 , and a diode 254 . The current-voltage conversion circuit 251 has an operational amplifier 2511 and a feedback element 2512 . The feedback element 2512 is provided in the feedback route of the operational amplifier 2511 and has two cells similar to the cells provided in the sensor device 21b. Note that the number of cells of the feedback element 2512 is not limited to two. The number of cells of the feedback element 2512 may be adjusted according to the degree of amplification by the operational amplifier 2511 and the number of cells forming the sensor device 21b. The feedback element 2512, for example, is provided three-dimensionally with respect to the cells that constitute the sensor device 21b. In other words, the feedback element 2512 is provided, for example, in the lower layer, ie, on the back side of the cell that constitutes the sensor device 21b. For example, the substrate 212 is shared by the sensor device 21b and the feedback element 2512, and a first insulating film 213, a first electrode 214, a second insulating film 215, and a vibrating film portion 216 are provided on the back side of the substrate 212 in the same manner as the sensor device 21b. , and a second electrode 217 are provided. Note that the sensor device 21b and the feedback element 2512 may be independent.

Protection switches 252 and 253 are connected to the input terminal and output terminal of operational amplifier 2511, respectively. The protection switches 252 and 253 cut off the wiring when a voltage higher than a predetermined voltage is applied.

The diode 254 is provided in parallel with the current-voltage conversion circuit 251 . Diode 254 passes a signal when the voltage value across its terminals exceeds a predetermined value.

When transmitting ultrasonic waves from the sensor device 21b, an AC drive voltage is supplied from the latter stage. The transmission drive circuit/reception detection circuit 25b applies an AC drive voltage to the second electrode 217 via the diode 254 . At this time, the protection switches 252 and 253 are supplied with a voltage higher than the predetermined voltage value, so the wires are cut off. As a result, an electrostatic attraction is generated between the first electrode 214 and the second electrode 217, and the vibrating film portion 216 vibrates at a predetermined cycle, thereby generating ultrasonic waves in the sensor device 21b.

When the sensor device 21b receives a reflected ultrasonic wave signal, the vibrating film portion 216 vibrates, and a minute current is generated in the second electrode 217 by electrostatic induction. Since no high voltage is applied at this time, the diode 254 disconnects the wiring, and the protection switches 252 and 253 connect the wiring. The operational amplifier 2511 of the current-voltage conversion circuit 251 receives a minute current through the coupling capacitor, converts the received minute current into a voltage, and outputs the converted signal to the subsequent stage. The input current is fed back via a feedback element 2512 provided on the feedback route.

Next, amplification by the operational amplifier 2511 will be described. In this description, the feedback element 2512 has two cells as an example.

The impedance _Zxdcr2 of the sensor device 21b shown in FIG. 6 is
_Zxdcr2 = _Zx2 / _Nt2 (7)
is represented. _Zx2 represents the impedance of one cell forming the sensor device 21b, and _Nt2 represents the number of cells forming the sensor device 21b.

The impedance Zf of the feedback element 2512 shown in FIG. 6 is
Z _f =Z _x2 /N _f (8)
is represented. Z _x2 represents the impedance of one cell that makes up the feedback element 2512 and N _f represents the number of cells that make up the feedback element 2512 .

The IV conversion amplification factor G _IV of the operational amplifier 2511 is obtained from the impedance Z _f of the feedback element 2512 and the impedance Z _xdcr2 of the sensor device 21b, for example, as follows.
_GIV = _Zf / _Zxdcr2 (9)
Substituting equations (7) and (8) into equation (9) yields
_GIV = ( _Zx2 / _Nf )/( _Zx2 / _Nt2 )
= _Nt2 / _Nf (10)
As a result, the cell impedance _Zx2 is no longer included in the IV conversion amplification factor _GIV . That is, according to equation (10), the signal converted by the operational amplifier 2511 is no longer affected by the impedance _Zx2 of the cell.

Next, the front end of the conventional drive detection circuit will be described for comparison with the front end of the transmission drive circuit/reception detection circuit 25b according to the second embodiment. FIG. 7 is a schematic diagram showing a configuration example of a front end of a conventional drive detection circuit. In the drive detection circuit shown in FIG. 7, a feedback resistor and a feedback capacitor are provided in the feedback route of the operational amplifier.

Assuming that the impedance of the feedback resistor is R _f2 and the impedance of the feedback capacitor is C _f2 , the impedance Z _f of the feedback route shown in FIG.
Z _f =R _f2 //C _f2 (11)
(However, Z ₁ //Z ₂ represents the parallel connection of Z ₁ and Z _2. )
is represented. Then, the IV conversion amplification factor G _IV of the operational amplifier shown in FIG. 7 is obtained from the equations (7), (9) and (11) as follows.

G _IV = (R _f2 //C _f2 )/(Z _x2 /N _t2 )
=(R _f2 //C _f2 )×N _t2 /Z _x2 (12)
Thus, the cell impedance Z _x2 remains in the IV conversion gain G _IV . That is, according to equation (12), the signal converted by the operational amplifier shown in FIG. 7 is affected by the impedance _Zx2 of the cell. Therefore, the frequency band of the received signal may be restricted.

As described above, in the second embodiment, the sensor device 21b has at least one CMUT cell that generates ultrasonic waves based on a driving signal, receives reflected ultrasonic wave signals, and converts them into electrical signals. . The transmission drive circuit/reception detection circuit 25b converts a minute current into a voltage with an operational amplifier 2511 as a front end, and feeds back the input minute current in a loop provided with a matching element (feedback element) 2512 using a CMUT. I am trying to let As a result, the configuration of the front end of the transmission driving circuit/receiving detection circuit 25b as receiving means corresponds to the electrical characteristics of the sensor device 21b.

Further, according to the front end configuration according to the second embodiment, it is possible to integrally integrate the CMUT as the ultrasonic transducer, the CMUT as the feedback element 2512 and the operational amplifier 2511 .

According to at least one embodiment described above, it is possible to match the impedance of the reception front-end circuit with the impedance of the sensor device. Therefore, the signal from the sensor device can be transmitted with high efficiency.

The word "processor" used in the description of the embodiments is, for example, a CPU (central processing unit), a GPU (Graphics Processing Unit), or an application specific integrated circuit (ASIC)), a programmable logic device (eg, Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA)). The processor realizes its functions by reading and executing the programs stored in the memory circuit. It should be noted that instead of storing the program in the memory circuit, the program may be directly installed in the circuit of the processor. In this case, the processor realizes its function by reading and executing the program embedded in the circuit. Note that each processor in each of the above embodiments is not limited to being configured as a single circuit for each processor, but may be configured as a single processor by combining a plurality of independent circuits to realize its function. good too. Furthermore, a plurality of components in each of the above embodiments may be integrated into one processor to realize its function.

While several embodiments have been described, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations of embodiments can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 1, 1a Ultrasonic diagnostic apparatus 10, 10a Device main body 11, 11a Ultrasonic transmitting circuit 111 Pulse generator 112 Transmission delay circuit 113 Pulser circuits 12, 12a Ultrasonic receiving circuit 121 Preamplifier 1211 LNA
1212 Feedback element 122 A/D converter 123 Demodulator 124 Beamformer 125 First capacitor 126 Second capacitor 127 Third capacitor 13 Internal storage circuit 14 Image memory 15 Input interface 16 Output Interface 17 Communication interface 18 Processing circuit 181 B-mode processing function 182 Doppler processing function 183 Image generation function 184 Display control function 185 System control function 20, 20a, 20b Ultrasonic probes 21, 21b Sensor device 211, 211-1, 211-2 Ultrasonic transducer 212 Substrate 213 First insulating film 214 First electrode 215 Second insulating film 216 Vibration film 217 Second electrode 22a Transmission circuit 23a Receiving circuit 231...Preamplifier 2311...LNA
2312 Feedback element 232 First capacitor 24b DC voltage source 25b Transmission drive circuit/reception detection circuit 251 Current voltage conversion circuit 2511 Operational amplifier 2512 Feedback elements 252, 253 Protection switch 254 Diode 30 Input device 40 Display device 50 External device

Claims (11)

a sensor device having at least one ultrasonic transducer that generates an ultrasonic wave based on a drive signal, receives a reflected wave signal of the ultrasonic wave, and converts it into an electrical signal;
an ultrasonic transducer corresponding to the ultrasonic transducer of the sensor device as a matching element for matching impedance with the sensor device; and a receiving means for receiving the electrical signal. Device. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein said receiving means has an amplifier circuit that amplifies said electrical signal and feeds back part of said amplified electrical signal through a loop in which said matching element is arranged. 3. The ultrasonic diagnostic apparatus according to claim 2, wherein said receiving means is an ultrasonic wave receiving circuit provided in the apparatus main body. 3. The ultrasonic diagnostic apparatus according to claim 2, wherein said receiving means is a receiving circuit provided in an ultrasonic probe. The ultrasonic diagnostic apparatus according to any one of claims 1 to 4, wherein the ultrasonic transducer is a piezoelectric transducer. The ultrasonic diagnostic apparatus according to any one of claims 1 to 4, wherein the ultrasonic transducer is a MUT (Micromachined Ultrasound Transducer). 7. The ultrasonic diagnostic apparatus according to claim 6 , wherein the MUT of said sensor device and the MUT of said receiving means are provided on a common substrate. a sensor device having at least one ultrasonic transducer that generates an ultrasonic wave based on a drive signal, receives a reflected wave signal of the ultrasonic wave, and converts it into an electrical signal;
an ultrasonic transducer corresponding to the ultrasonic transducer of the sensor device as a matching element for matching impedance with the sensor device, and receiving means for receiving the electrical signal. probe. 9. The ultrasonic probe according to claim 8, wherein the ultrasonic transducer is a MUT (Micromachined Ultrasound Transducer). 10. The ultrasonic probe according to claim 9, wherein the MUT of said sensor device and the MUT of said receiving means are provided on a common substrate. a sensor device having at least one ultrasonic transducer that generates an ultrasonic wave based on a drive signal, receives a reflected wave signal of the ultrasonic wave, and converts it into an electrical signal;
a circuit for amplifying an electrical signal output from the sensor device, the amplifier circuit having an ultrasonic transducer corresponding to the ultrasonic transducer of the sensor device on a feedback path connecting an output and an input; Ultrasound diagnostic equipment.

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