JP2006319713A - Ultrasonic probe and body cavity insertion-type ultrasonic diagnostic device mounted with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic probe in which a low-voltage signal is transmitted to a signal transmission cable between an ultrasonic vibrator and an observation device, the signal is boosted near the ultrasonic vibrator and the boosted voltage is applied to the vibrator. <P>SOLUTION: The above problem is solved by the ultrasonic probe provided with an ultrasonic vibrator 6a for transmitting and receiving an ultrasonic wave; and an high voltage generating means 7 for generating a high voltage on the basis of a driving signal when the driving signal for driving the ultrasonic vibrator is input and applying the high voltage to the ultrasonic vibrator. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an intracorporeal ultrasonic diagnostic apparatus equipped with an ultrasonic transducer.

  An ultrasonic diagnostic method is widely used in which an ultrasonic wave is irradiated toward the inner wall of a body cavity, and an internal state is imaged and diagnosed from the echo signal. One of the equipment used for this ultrasonic diagnostic method is an ultrasonic endoscope scope.

  An ultrasonic endoscope scope has an ultrasonic probe attached to the distal end of an insertion portion to be inserted into a body cavity. This ultrasonic probe converts an electrical signal into an ultrasonic wave and irradiates it into the body cavity. The reflected ultrasonic waves are received and converted into electric signals.

  Conventionally, in an ultrasonic probe, a ceramic piezoelectric material PZT (lead zirconate titanate) has been used as a piezoelectric element for converting an electrical signal into an ultrasonic wave, but a silicon semiconductor substrate was processed using silicon micromachining technology. Capacitive ultrasonic transducers (hereinafter referred to as “c-MUT”) are attracting attention. This is one of the elements collectively referred to as a micromachine (MEMS: Micro Electro-Mechanical System).

  Recently, the diagnostic modality called harmonic imaging has come into the spotlight because it enables unprecedented high-accuracy ultrasonic diagnosis. Therefore, in the intracavitary ultrasonic diagnostic equipment, the standard equipment of this diagnostic modality is It has become indispensable. Therefore, it has been desired to further increase the bandwidth of the ultrasonic transducer.

  As described above, a capacitive ultrasonic transducer (cMUT) using a micromachine process has recently attracted attention. This cMUT not only does not contain heavy metals such as lead, but also can easily obtain broadband characteristics. Therefore, it is suitable for the above-described harmonic imaging.

  FIG. 19 shows an example of a conventional cMUT. The figure is a cMUT disclosed in Patent Document 1. The ultrasonic transducer is formed by a plurality of capacitive micromachine ultrasonic transducers (cMUT). Each cell constituting the cMUT has a charged diaphragm 206. The charged vibration plate 206 faces the oppositely charged substrate 205 with a capacity.

  The diaphragm 206 is bent toward the substrate 205 by bias charging. In addition, the substrate 205 has a central portion 28 that protrudes from the center of the diaphragm 206 so that the charge of the cell has the maximum density at the center of vibration of the diaphragm 206. The drive pulse waveform fed to the cell is distorted in advance for operation by harmonics. This is done in view of the non-linear operation of the apparatus in order to reduce the distortion of the transmitted ultrasonic signal in the harmonic band.

  Since the cMUT cell is processed by a conventional semiconductor process, it can be integrated with an auxiliary vibrator circuit such as the bias charge regulator 201. The cMUT cell can also be processed by microstereolithography. As such, the cells are formed using a variety of polymers and other materials.

  This ultrasonic observation apparatus is provided with a high voltage switch in the ultrasonic probe in order to operate by harmonics. In the ultrasonic observation apparatus, there are provided pulse generation means and control means. The pulse generating means can output a pulse having an arbitrary voltage value with an arbitrary waveform. The control means controls the outputs of the high voltage switch and the pulse generating means based on the scanning timing of the ultrasonic transducer.

On the other hand, the applicant of the present invention has proposed a method in which the DC voltage application timing is applied only for a time that matches the rf signal application timing (Patent Document 2).
FIG. 20 shows an example (part 2) of a conventional ultrasonic transducer driving method. This figure is a test probe disclosed in Patent Document 3. This test probe is designed to minimize the effects of electrical interference caused by the relatively long connection cable between the test probe and the ultrasonic signal evaluation device in addition to the known circuit. , Including other actuation circuits. In Patent Document 3, the test probe includes the above-described circuit, but the circuit is not excessively large. Also, the operation is not made difficult when performing the ultrasonic test.

  A transmitter circuit 210 is incorporated in the probe housing of the test probe. The transmission circuit 210 includes a step-up coil 211, a VMOS field effect transistor 213, a control circuit 214, and a capacitor 215. The VMOS field effect transistor 213 performs an ON / OFF operation according to the control signal 212.

  The transmission circuit 210 operates as follows. The high-density charge is charged in the capacitor 215 through the booster coil 211. When the charge amount of the capacitor 215 is maximized, a control signal is output from the control circuit 214 to the switch drive terminal of the VMOS field effect transistor 213. Then, the VMOS field effect transistor 213 is turned on. Then, a discharge occurs in a closed circuit by the ON resistance, the resistor 216, and the capacitor 215. A voltage generated in the resistor 216 by the discharge current is applied to the piezoelectric vibrator.

  However, in order to increase the voltage induced by this method, the inductance of the booster coil 211 must be increased. Therefore, resonance occurs between the capacitor 215 and the coil 211, and a drive pulse including ringing is generated. This ringing signal is directly applied to the piezoelectric vibrator, leading to a decrease in S / N.

  FIG. 21 shows an example (part 3) of a conventional ultrasonic transducer driving method. FIG. 21A shows an ultrasonic diagnostic apparatus disclosed in Patent Document 4. FIG. 21 (b) is a simplified version of FIG. 21 (a). Patent Document 4 does not necessarily intend to prevent the above ringing, but discloses that the effect of electrical interference caused by a long connection cable is minimized.

  In FIG. 21, the ultrasonic probe 220 and the ultrasonic observation apparatus 221 are described. An ultrasonic signal is transmitted / received from an ultrasonic transducer 222 provided in the ultrasonic probe to ultrasonically scan the subject. The ultrasonic diagnostic apparatus 221 can obtain an ultrasonic tomographic image based on the received ultrasonic signal.

  A high voltage switch 223 is provided in the ultrasonic probe 220. In the ultrasonic observation apparatus, pulse generation means 227 and control means 228 are provided. The pulse generating means 227 can output a pulse having an arbitrary voltage value with an arbitrary waveform. The control unit 228 controls the outputs of the high voltage switch 223 and the pulse generation unit 227 based on the scanning timing of the ultrasonic transducer.

With such a configuration, the electric circuit inside the ultrasonic probe is not enlarged. In addition, a high voltage pulse signal for driving the ultrasonic transducer can be efficiently generated in the probe. In addition, it is possible to obtain a good ultrasonic image that is not affected by the interference with the cable, and to suppress the noise radiated outside. Also, since there are no resonating elements in the circuit, ringing does not occur.
JP-T-2004-503313 JP 2004-176039 A Japanese Patent Publication No. 63-026341 Japanese Patent No. 3062313 Nakamura, Y., Adachi, Yoshinori, “Piezoelectric Transformers Using Lithium Niobate Single Crystals”, IEICE Transactions, A, Vol. J80-A, no. 10, pp. 1694-1698, October 1997

  However, in the conventional example, in order to apply a high pulse voltage to the piezoelectric vibrator, it is necessary to increase the output voltage of the amplifier. The high voltage pulse is transmitted through a long connection cable as it is.

  The ultrasonic endoscope requires a long signal transmission cable between the ultrasonic transducer and the observation device. However, transmission of a high voltage signal to the cable becomes a source of RF noise and is not preferable. It is desirable that the voltage transmitted to the cable be a low voltage, and a voltage high enough to receive a sufficient echo signal is applied only in the vicinity of the ultrasonic transducer only when transmitting ultrasonic waves.

  In the body cavity insertion type ultrasonic diagnostic apparatus, a long cable is wired between the ultrasonic transducer and the signal control unit. In general, it is necessary to apply a high voltage pulse, and the influence of radiation or flying of RF noise in the cable has been a problem.

  Moreover, in recent years, a capacitive micromachined ultrasonic transducer (cMUT) that has a wide bandwidth that can handle harmonic imaging, which is indispensable as a diagnostic modality, and that is environmentally friendly, needs to superimpose not only high voltage pulses but also high DC voltages. there were.

  In addition, the inductor requires space. For this reason, the apparatus described in Patent Document 2 has a problem that the ultrasonic probe cannot be miniaturized or cannot be made into an IC. In addition, since a high voltage pulse with a steep rise and fall is transmitted between the observation apparatus and the ultrasonic probe, the noise radiated to the outside becomes large, and the regulations regarding noise cannot be cleared.

  In view of the above problems, the present invention transmits a low voltage signal to the signal transmission cable between the ultrasonic transducer and the observation device, boosts the pressure near the ultrasonic transducer, and applies the boosted voltage to the transducer. An ultrasonic probe and an intra-body cavity insertion type ultrasonic diagnostic apparatus are provided.

  According to the first aspect of the present invention, when an ultrasonic transducer that transmits and receives ultrasonic waves and a drive signal that drives the ultrasonic transducer are input, the drive signal By providing an ultrasonic probe characterized by comprising high voltage generating means for generating a high voltage based on the above and applying the high voltage to the ultrasonic transducer in close proximity to each other at the tip thereof Can be achieved.

  According to the second aspect of the present invention, the ultrasonic transducer is a capacitive ultrasonic transducer (cMUT) manufactured using a micromachine manufacturing process. This can be achieved by providing an ultrasonic probe according to claim 1.

  According to the invention described in claim 3, the above-described problem is characterized in that the ultrasonic transducer is a piezoelectric transducer (p-MUT) manufactured using a micromachine manufacturing process. This can be achieved by providing the ultrasonic probe according to claim 1.

  According to the invention described in claim 4, the high voltage generating means outputs a DC high voltage based on the drive signal when the drive signal is a DC low voltage. This can be achieved by providing the ultrasonic probe according to claim 1.

  According to the invention described in claim 5, the high voltage generating means outputs an AC high voltage based on the drive signal when the drive signal is a DC low voltage. This can be achieved by providing the ultrasonic probe according to claim 1.

  According to the invention described in claim 6, the high voltage generating means outputs a high DC voltage based on the drive signal when the drive signal is an AC low voltage. This can be achieved by providing the ultrasonic probe according to claim 1.

  According to the seventh aspect of the present invention, when the drive signal is an AC low voltage, the high voltage generating means outputs an AC high voltage based on the drive signal. This can be achieved by providing the ultrasonic probe according to claim 1.

  According to an eighth aspect of the present invention, the frequency of the drive signal of the AC high voltage is substantially equal to the resonance frequency of the ultrasonic transducer. This can be achieved by providing an ultrasonic probe according to claim 5 or 7.

  The present invention provides the ultrasonic probe according to claim 5 or 7, wherein the AC high voltage is a burst wave according to the invention described in claim 9. Can be achieved.

  According to the invention described in claim 10 of the claim, the high voltage generating means includes a boosting means for boosting the voltage of the drive signal. This can be achieved by providing an ultrasonic probe.

  The object is achieved by providing an ultrasonic probe according to claim 10, wherein the boosting means is an electromagnetic transformer. it can.

  According to the invention described in claim 12, the above-mentioned object can be achieved by providing the ultrasonic probe according to claim 10, wherein the boosting means is a piezoelectric transformer. .

  According to the invention described in claim 13, the above-mentioned object can be achieved by providing the ultrasonic probe according to claim 12, wherein the piezoelectric transformer is a Rosen type. .

  According to the invention described in claim 14 of the claim, the piezoelectric transformer is made of lithium niobate, and the ultrasonic probe according to claim 12 is provided. Can be achieved.

  According to the invention described in claim 15, the high voltage generation means further converts the drive signal into an AC signal when the drive signal is a DC signal. It can be achieved by providing the ultrasonic probe according to claim 10, further comprising an oscillating means for outputting to the boosting means.

  According to the invention described in claim 16, the high voltage generating means further applies a DC bias voltage to the AC high voltage output from the boosting means. It can achieve by providing the ultrasonic probe of Claim 10 characterized by having.

  According to the invention described in claim 17, the DC bias applying unit is configured to convert the AC high voltage output from the boosting unit into a first AC high voltage and a second AC. Branch means for branching to high voltage, DC conversion means for converting the first AC high voltage to DC, and addition for adding the DC voltage output from the DC conversion means and the second AC high voltage It can be achieved by providing an ultrasonic probe according to claim 16.

  According to the invention described in claim 18, the adding means superimposes the second AC high voltage on a period during which the DC voltage is generated. This can be achieved by providing an ultrasonic probe according to claim 17.

  The ultrasonic probe according to claim 18, wherein the subject is according to the invention described in claim 19, wherein the period during which the DC voltage is generated does not exceed 10 μsec. Can be achieved by providing.

  According to the invention described in claim 20, the addition means is provided with means for slowing the rising and falling of the DC voltage. This can be achieved by providing an ultrasonic probe.

  According to the invention described in claim 21, the above-described problem is characterized in that the p-MUT is formed on a silicon substrate, and further, a switch circuit and a rectifier are provided on the silicon substrate. This can be achieved by providing the ultrasonic probe according to Item 3.

  According to the invention described in claim 22, the object is to provide the ultrasonic probe according to claim 2, wherein the cMUT is an electret capacitor using an electret film. Can be achieved.

  According to the invention described in claim 23, at least one of a step-up transformer, a switch circuit, a rectifier, and a charge amplifier can be formed on or inside the silicon substrate of the cMUT. This can be achieved by providing the ultrasonic probe according to claim 2.

  According to the invention described in claim 24 of the present invention, the switch circuit, the rectifier, and the charge amplifier are integrated using a semiconductor process on or in the silicon substrate constituting the cMUT. This can be achieved by providing an ultrasonic probe according to claim 2.

  According to the invention described in claim 25, the object is to provide a switch circuit, a rectifier, an adder, a delay circuit, and a charge amplifier on or in a silicon substrate on which the cMUT is formed. It can achieve by providing the ultrasonic probe of Claim 2 characterized by the above-mentioned.

  According to the invention described in claim 26 of the claims, the object is to provide an intracorporeal insertion type ultrasonic diagnostic apparatus comprising the ultrasonic probe according to any one of claims 1 to 25. Can be achieved.

  By using the present invention, it is possible to transmit only a low voltage signal to the cable without efficiently increasing the electrical circuit inside the ultrasonic probe and efficiently generate a high voltage pulse for driving the ultrasonic transducer in the probe. it can. In addition, the influence of noise caused by the cable can be prevented.

<First Embodiment>
In this embodiment, a body cavity insertion type ultrasonic diagnostic apparatus using a piezoelectric vibrator as an ultrasonic vibrator will be described.

  FIG. 1 is a block diagram of a circuit configuration of a body cavity insertion type ultrasonic diagnostic apparatus using a piezoelectric vibrator as an ultrasonic vibrator in the present embodiment. In FIG. 1, the intracorporeal insertion type ultrasonic diagnostic apparatus 1 includes an insertion unit 2 and an observation apparatus 5.

  The insertion part 2 has an elongated tubular shape for insertion into a body cavity. The insertion portion 2 includes an ultrasonic probe 3, a bending portion, and a flexible tube portion 4 in order from the distal end side. The ultrasonic probe 3 is provided with an ultrasonic transducer and transmits and receives an ultrasonic signal. The bending portion is a bendable portion located at the rear end of the ultrasonic probe 3. The flexible tube portion is positioned at the rear end of the curved portion and has a small diameter and a long length and is flexible.

  The ultrasonic probe 3 includes a piezoelectric vibrator 6a and high voltage generating means 7. A coaxial cable 8 (core wire 8a and shield wire 8b) is built in the bending portion and the flexible tube portion 4.

  The observation device 5 has a function of generating a control signal for turning on / off the high-voltage high-speed SW, outputting a low-voltage RF pulse signal, processing the received signal to convert it into an image signal, and the like.

  The cable transmission signal Sg1 is transmitted from the observation device 5 to the high voltage generation means 7 via the core wire 8a of the coaxial cable 8. The high voltage generating means 7 outputs an alternating high voltage when a direct current low voltage is input, outputs an alternating high voltage when the alternating low voltage is input, and the like.

  The high voltage generating means 7 includes a boosting means 7a (for example, an electromagnetic transformer or a piezoelectric transformer). The booster 7a boosts the voltage (for example, 10 V or less) of the cable transmission signal Sg1 to a predetermined value (for example, 50 V to several hundred V) in order to obtain a voltage necessary for driving the vibrator.

  Then, the high voltage generation means 7 transmits the boosted signal (vibrator drive signal) Sg2 to the piezoelectric vibrator 6a. Further, when an AC high voltage signal is output from the high voltage generating means 7, the frequency of the AC high voltage signal is adjusted to be substantially equal to the resonance frequency of the piezoelectric vibrator.

  The vibrator drive signal Sg2 is input to one electrode of the piezoelectric vibrator 6a and a voltage is applied to the electrode. The other electrode of the piezoelectric vibrator 6 a is connected to the shield wire 8 b of the coaxial cable 8 and grounded. Therefore, the piezoelectric vibrator vibrates due to the voltage difference between the electrodes, and ultrasonic waves are radiated from the surface of the piezoelectric vibrator 6a.

  Hereinafter, an embodiment in which an electromagnetic step-up transformer and a piezoelectric transformer are used as the step-up means 7a will be described. Since the electromagnetic step-up transformer has a relatively low output impedance, it can drive a load having a relatively low impedance. On the other hand, the piezoelectric transformer has a higher boosting efficiency and is smaller than the electromagnetic boost transformer.

Example 1
FIG. 2 shows a block diagram of a circuit configuration of an intracorporeal insertion type ultrasonic diagnostic apparatus using an electromagnetic step-up transformer as a step-up unit in the present embodiment. The high voltage generating means 7 in this embodiment includes a step-up transformer 10, a rectifier 11, and a switch 12.

  The step-up transformer 10 includes a step-up transformer primary side coil 10a and step-up transformer secondary side coils 10b and 10c. The switch 12 has switch terminals 12a, 12b, 12c, and 12d. The switch 12 is for switching between ultrasonic transmission and ultrasonic reception. The switch 12 is in a state in which the switch terminals 12c and 12d are electrically connected except during ultrasonic transmission (a state in which a DC voltage is not applied to the switch drive terminal).

  At the time of ultrasonic transmission, the cable transmission signal Sg1 is transmitted from the observation device 5 and input to the step-up transformer primary coil 10a of the step-up transformer 10. As a result, a boosted AC signal is generated in the step-up transformer secondary coils 10b and 10c. In the present embodiment, the cable transmission signal Sg1 is a burst wave having a specific frequency.

  The high voltage output from the step-up transformer secondary coil 10c side is converted into a DC voltage through the rectifier 11 to be a DC voltage. When the DC voltage is applied to the switch drive terminal of the switch 12, the switch terminals 12a and 12b are brought into conduction.

  Then, the high voltage output from the step-up transformer secondary coil 10b side is applied to one electrode of the piezoelectric vibrator 6a through the conductive switch terminals 12a-12b. The vibrator drive signal Sg2 output from the step-up transformer secondary coil 10b is a higher-voltage burst wave in which the amplitude of the cable transmission signal Sg1 is increased.

When a high voltage is applied, the piezoelectric vibrator 6a vibrates and ultrasonic waves are emitted from the surface of the piezoelectric vibrator 6a.
At the time of ultrasonic reception, since the cable transmission signal Sg1 is not transmitted from the observation device 5, no AC high voltage is generated by the step-up transformer 10. Therefore, since the voltage applied to the switch drive terminal of the switch 12 is not generated, the switch terminals 12c and 12d are in a conductive state.

  At this time, when receiving the ultrasonic wave, the piezoelectric vibrator 6a converts the ultrasonic wave into an electric signal. The ultrasonic reception signal Sg3 converted into this electric signal is transmitted to the observation device 5 through the core wire 8a of the coaxial cable 8 through the switch terminals 12c-12d.

  As described above, by installing the high voltage generating means 7 in the vicinity of the piezoelectric vibrator 6a, a low voltage signal is transmitted to the cable, and a high voltage pulse for driving the piezoelectric vibrator is efficiently generated in the ultrasonic probe. be able to. In addition, the influence of noise caused by the cable can be prevented.

(Example 2)
FIG. 3 is a block diagram of a circuit configuration of an intracorporeal ultrasonic diagnostic apparatus using a piezoelectric step-up transformer as a step-up unit in the present embodiment. The high voltage generating means 7 in this embodiment is composed of a piezoelectric transformer 20, a resistor (DC resistance) 21, a rectifier 11, and a switch 12.

  The piezoelectric transformer 20 includes a piezoelectric vibrator 20a, a piezoelectric transformer primary electrode 20b, a ground electrode 20c, and a piezoelectric transformer secondary electrode 20d. The switch 12 is in a state in which the switch terminals 12c and 12d are electrically connected except during ultrasonic transmission (a state in which a DC voltage is not applied to the switch drive terminal).

  At the time of ultrasonic transmission, the cable transmission signal Sg1 is transmitted from the observation device 5. In the present embodiment, the cable transmission signal Sg1 is a burst wave having a specific frequency. The cable transmission signal Sg1 is input to the piezoelectric transformer primary electrode 20b of the piezoelectric transformer 20. Then, a high voltage is output from the piezoelectric transformer secondary electrode 20d. The vibrator drive signal Sg2 output from the piezoelectric transformer secondary electrode 20d is a higher-voltage burst wave in which the amplitude of the cable transmission signal Sg1 is increased.

  Since the voltage input to the primary side electrode 20b is grounded via the DC resistor 21, the displacement current due to the voltage input to the primary side electrode 20b also flows to the DC resistor 21 and is generated at both ends of the DC resistor 21. Generate power. This voltage is converted into a direct current voltage through the rectifier 11. When the DC voltage is applied to the switch drive terminal of the switch 12, the switch terminals 12a and 12b are brought into conduction. Then, the high-voltage vibrator drive signal Sg2 is transmitted to the piezoelectric vibrator 6a through the switch terminals 12a-12b.

  At the time of ultrasonic reception, the cable transmission signal Sg1 is not transmitted from the observation device 5. Accordingly, no current flows through the DC resistor 21 and the SWs 12a and 12b do not conduct, and therefore no high voltage is generated by the piezoelectric transformer 20. Therefore, since the voltage applied to the switch drive terminal of the switch 12 is not generated, the switch terminals 12c and 12d are in a conductive state.

  At this time, when receiving the ultrasonic wave, the piezoelectric vibrator 6a converts the ultrasonic wave into an electric signal. The ultrasonic reception signal Sg3 converted into this electric signal is transmitted to the observation device 5 through the core wire 8a of the coaxial cable 8 through the switch terminals 12c-12d. Here, the piezoelectric vibrator 6a is not limited to a bulk piezoelectric vibrator, and may be a so-called p-MUT in which a piezoelectric thin film is formed on a membrane. In this case, it is preferable to manufacture the Si substrate and form the SWs 12a and 12b and the rectifier 11 on the Si substrate, which facilitates compactness.

  FIG. 4 shows an example of the configuration of a piezoelectric vibrator (p-MUT) manufactured by the micromachine process in the present embodiment. In the p-MUT, a (gap) 6a-3 is formed on a silicon substrate 6a-4, and a membrane 6a-2 is formed on the cavity 6a-3. The membrane 6a-2 includes a lower electrode 6a-5, and the lower electrode 6a-5 is provided on the upper surface of the membrane. A piezoelectric film 6a-6 is formed on the upper surface of the lower electrode 6a-5. An upper electrode 6a-1 is formed on the upper surface of the piezoelectric film 6a-6. A signal is transmitted to the lower electrode 6a-5 via the switch 12. The upper electrode 6a-1 is a ground electrode.

Next, the piezoelectric transformer 20 will be described.
FIG. 5 shows a basic and best-studied Rosen structure of a piezoelectric transformer (Non-Patent Document 1). The common ground electrode is attached to the left half of the lower surface of the plate. The piezoelectric ceramic plate is polarized by applying a high DC voltage to the input portion in the thickness direction and the output portion in the length direction.

  When a voltage Vin having a resonance frequency of longitudinal vibration determined by the dimension in the length direction is applied to the input electrode, longitudinal vibration occurs due to the piezoelectric transverse effect, and the high voltage Vout is applied to the output electrode attached to the end via the piezoelectric longitudinal effect. Occurs. The step-up ratio Vout / Vin when there is no load at the output end is expressed by equation (1).

Vout / Vin ∝ k ₃₁ k ₃₃ Q (L / T) (1)
Accordingly, a transformer having a large step-up ratio can be configured by using a piezoelectric material having a product of the transverse effect electromechanical coupling coefficient k ₃₁ and the longitudinal effect electromechanical coupling coefficient k ₃₃ and a large mechanical quality factor Q value.

In this embodiment, lithium niobate (LiNbO ₃ ) is used as the piezoelectric transformer. A piezoelectric transformer using a LiNbO ₃ single crystal has the following features compared to a piezoelectric transformer using a conventional ceramic.

First, the LiNbO ₃ crystal does not need to be polarized so that the polarization direction is orthogonal between the input part and the output part by applying a DC high voltage like ceramic. Moreover, it has a high Q value of 1-2 × 10 ⁴ . Since k ₃₁ k ₃₃ is larger than ceramic, a high step-up ratio can be obtained. Also, the temperature rise during operation due to heat generation is small. Also, LiNbO ₃ has no internal stress and is not easily destroyed.

  FIG. 6 shows a piezoelectric transformer using lithium niobate in this example. The piezoelectric transformer 30 includes a lithium niobate single crystal substrate 31, a voltage input side electrode 32 (that is, the piezoelectric transformer primary side electrode 20b), a voltage output side electrode 33 (that is, the piezoelectric transformer secondary side electrode 20d), and a counter electrode 33a. (Provided on the bottom surface of the lithium niobate single crystal substrate 31 so as to face the voltage output side electrode 33), stripe electrodes 34 and 35, piezoelectric transformer support portions 36a and 36b, input signal wiring 37, output signal wiring 38.

  When the lateral length of the lithium niobate single crystal substrate 31 is represented by L, the lateral length of the voltage input side electrode 32 is L / 2. The piezoelectric transformer support portions 36a and 36b are respectively provided at positions L / 4 from the end, and the reason will be described with reference to FIG. The piezoelectric transformer support portions 36a and 36b are terminals for connecting the input signal wiring 37 and the output signal wiring 38 to the voltage input side electrode 32 and the voltage output side electrode 33, respectively.

  FIG. 7 shows vibration displacement when observed from the side surface direction of the lithium niobate single crystal substrate 31 of FIG. Reference numeral 41 denotes a vibration neutral surface. When a burst wave is applied to the voltage input side electrode 32 via the input signal wiring 37, the vibration of the lithium niobate is caused at the position of L / 4 from the end as a node (vibration). Displacement 42). Therefore, the piezoelectric transformer support portions 36a and 36b are provided at the portions serving as the nodes.

  The piezoelectric transformer support 36 b and the voltage output side electrode 33 are electrically connected by the stripe electrodes 34 and 35. Then, the high voltage signal generated on the surface of the voltage output side electrode 33 is output from the output signal wiring 38 through the stripe electrodes 34 and 35.

  Thereby, compared with the case where the output signal wiring 38 is connected to the voltage output side electrode 33, it is possible to prevent the vibration of the lithium niobate single crystal substrate 31 from being hindered. The voltage output side electrode 33 vibrates in a direction perpendicular to the end face.

FIG. 8 is a modification (No. 1) of FIG. In FIG. 8, the voltage output side electrode 33 and the output signal wiring 38 are electrically connected by the lead line 51.
FIG. 9 is a second modification of FIG. In FIG. 9, the voltage output side electrode 33 and the output signal wiring 38 are electrically connected by the lead line 52.

  As described above, by installing the high voltage generating means 7 in the vicinity of the piezoelectric vibrator 6a, a low voltage signal is transmitted to the cable, and a high voltage pulse for driving the piezoelectric vibrator is efficiently generated in the ultrasonic probe. be able to. In addition, the influence of noise caused by the cable can be prevented.

<Second Embodiment>
In the present embodiment, an intracorporeal ultrasonic diagnostic apparatus using a capacitive ultrasonic transducer (cMUT) using a micromachine process as the ultrasonic transducer will be described.

  The structure of cMUT will be briefly described. First, a cavity (gap part, concave part) is provided in a silicon substrate, and a lower electrode is provided at the bottom of the cavity. A membrane is formed above the cavity, and an upper electrode film is included as one of the components of the membrane. The upper electrode film is a ground electrode.

  A unit composed of a recess forming a cavity and a membrane covering the recess is called a cell. An assembly of a plurality of transducer cells is referred to as a transducer element. This transducer element is a minimum unit for inputting and outputting drive control signals.

  The operation of the cMUT having such a configuration outline will be described. When a voltage is applied to a pair of upper and lower electrodes, the electrodes are pulled together, and when the voltage is reduced to 0, the operation returns. As a result of the vibration of the membrane by this vibration operation, an ultrasonic wave is generated, and the ultrasonic wave is irradiated upward of the upper electrode.

  FIG. 10 is a block diagram of an intracorporeal insertion type ultrasonic diagnostic apparatus using a capacitive ultrasonic transducer (cMUT) as an ultrasonic transducer in the present embodiment. FIG. 10 is obtained by replacing the piezoelectric vibrator 6a of FIG. 1 with a capacitive ultrasonic vibrator (cMUT) 6b. The basic configuration and operation of FIG. 10 are the same as those of FIG.

  The high voltage generating means 7 in this embodiment outputs a DC high voltage when a DC low voltage is input, outputs an AC high voltage when a DC low voltage is input, or inputs an AC low voltage. If a low voltage is input, a high DC voltage is output. If a low AC voltage is input, a high AC voltage is output.

  The high voltage generating means 7 includes a boosting means 7a (for example, an electromagnetic transformer or a piezoelectric transformer). The booster 7a boosts the voltage (for example, 10 V or less) of the cable transmission signal Sg1 to a predetermined value (for example, 50 V to several hundred V) in order to obtain a voltage necessary for driving the vibrator.

When an AC high voltage signal is output from the high voltage generating means 7, the frequency of the AC high voltage signal is adjusted to be substantially equal to the resonance frequency of the electrostatic ultrasonic transducer.
Hereinafter, an embodiment in which an electromagnetic step-up transformer and a piezoelectric transformer are used as the step-up means 7a will be described. Since the electromagnetic step-up transformer has a relatively low output impedance, it can drive a load having a relatively low impedance. On the other hand, the piezoelectric transformer has a higher boosting efficiency and is smaller than the electromagnetic boost transformer. In addition, since the piezoelectric transformer has a relatively high output impedance, it is preferable for a cMUT that requires a high impedance load. Here, the cMUT may not be a pure capacitor structure but may be an electret capacitor using an electret film.

Example 1
FIG. 11 is a block diagram of a circuit configuration of an intracorporeal insertion type ultrasonic diagnostic apparatus using an electromagnetic step-up transformer as a step-up unit in the present embodiment. The high voltage generating means 7 in this embodiment includes a step-up transformer 10, a rectifier 11, and a switch 12. These are the same as in FIG. A charge amplifier 60 is also provided. The switch 12 is in a state in which the switch terminals 12c and 12d are electrically connected except during ultrasonic transmission (a state in which a DC voltage is not applied to the switch drive terminal).

  The charge amplifier 60 has a function of performing impedance conversion (converting from high impedance to low impedance), a function of detecting charge on the electrode surface of the cMUT 6b, and a function of an amplifier. The function of detecting the charge is that the ultrasonic wave emitted from the membrane surface of the cMUT 6b is reflected in the body cavity, and when the cMUT 6b receives the reflected wave, the membrane vibrates according to the received intensity of the reflected wave, Since the charge on the upper electrode fluctuates in response to the vibration, it means a function of detecting the charge.

  At the time of ultrasonic transmission, the cable transmission signal Sg1 is transmitted from the observation device 5 and input to the step-up transformer primary coil 10a of the step-up transformer 10. As a result, a boosted AC signal is generated in the step-up transformer secondary coils 10b and 10c. In the present embodiment, the cable transmission signal Sg1 is a burst wave having a specific frequency.

  The voltage output from the step-up transformer secondary coil 10c side is converted into a rectifier 11 DC voltage. When the DC voltage is applied to the switch drive terminal of the switch 12, the switch terminals 12a and 12b become conductive.

  Then, the high voltage output from the step-up transformer secondary coil 10b side is applied to the lower electrode (upper side in the drawing) of the cMUT 6b through the conducting switch terminals 12a-12b. The vibrator drive signal Sg2 output from the step-up transformer secondary coil 10b is a higher-voltage burst wave in which the amplitude of the cable transmission signal Sg1 is increased.

When a high voltage burst wave is applied, the membrane of the cMUT 6b vibrates and ultrasonic waves are emitted from the membrane surface.
At the time of ultrasonic reception, in the time region where no driving burst wave has already occurred, the amplitude of the cable transmission signal Sg1 is 0, so that no AC high voltage is generated by the step-up transformer 10. Therefore, since the voltage applied to the switch drive terminal of the switch 12 is 0, the switch terminals 12c and 12d are in a conductive state.

  At this time, when the cMUT 6b receives the ultrasonic wave, the cMUT 6b converts the ultrasonic wave into an electric signal. The ultrasonic reception signal Sg3 converted into this electric signal is transmitted to the observation device 5 through the core wire 8a of the coaxial cable 8 through the switch terminals 12c-12d.

  As described above, by installing the high voltage generating means 7 in the vicinity of the capacitive ultrasonic transducer 6b, a low voltage signal is transmitted to the cable, and the capacitive ultrasonic transducer is driven in the ultrasonic probe. High voltage pulses can be generated efficiently. In addition, the influence of noise caused by the cable can be prevented. As described above, the cMUT is manufactured on the Si substrate by using a micromachine process. However, components other than the step-up transformer, such as the SW12, the rectifier 11, and the charge amplifier can be formed on or inside the Si substrate on which the cMUT is formed. In this way, further downsizing is possible.

(Example 2)
FIG. 12 shows a block diagram of a circuit configuration of an intracorporeal ultrasonic diagnostic apparatus using a piezoelectric step-up transformer as a step-up unit in the present embodiment. The high voltage generating means 7 in this embodiment is composed of a piezoelectric transformer 20, a resistor (DC resistance) 21, a rectifier 11, and a switch 12. These are the same as in FIG. Further, as in FIG. 11, a charge amplifier 60 is provided. The switch 12 is in a state in which the switch terminals 12c and 12d are electrically connected except during ultrasonic transmission (a state in which a DC voltage is not applied to the switch drive terminal).

  At the time of ultrasonic transmission, the cable transmission signal Sg1 is transmitted from the observation device 5. In the present embodiment, the cable transmission signal Sg1 is a burst wave having a specific frequency. The cable transmission signal Sg1 is input to the piezoelectric transformer primary electrode 20b of the piezoelectric transformer 20. Then, a high voltage is output from the piezoelectric transformer secondary electrode 20d. The vibrator drive signal Sg2 output from the piezoelectric transformer secondary electrode 20d is a higher-voltage burst wave in which the amplitude of the cable transmission signal Sg1 is increased.

  The voltage applied to the input side is divided by the impedance between the DC resistor 21 and the electrodes 20b-20c, and the divided piezoelectric signals at both ends of the DC resistor 21 are converted into a DC voltage by the rectifier 11. When the DC voltage is applied to the switch drive terminal of the switch 12, the switch terminals 12a and 12b become conductive. Then, the high-voltage vibrator drive signal Sg2 is applied to the cMUT 6b through the switch terminals 12a-12b.

  At the time of receiving the ultrasonic wave, the amplitude of the cable transmission signal Sg1 is 0 in the time region where the driving burst wave has not already been generated, so that no high voltage is generated by the piezoelectric transformer 20. Therefore, since the voltage applied to the switch drive terminal of the switch 12 is 0, the switch terminals 12c and 12d are in a conductive state.

  At this time, when the cMUT 6b receives the ultrasonic wave, the cMUT 6b converts the ultrasonic wave into an electric signal. The ultrasonic reception signal Sg3 converted into the electric signal is transmitted to the observation device 5 through the core wire 8a of the coaxial cable 8 through the switch terminals 12d-12c.

  In the present embodiment, it is preferable that the SW 12, the rectifier 11, and the charge amplifier 60 are integrated on the Si substrate constituting the cMUT or inside the semiconductor substrate by using a semiconductor process, which is preferable.

(Example 3)
In this embodiment, an intracorporeal ultrasonic diagnostic apparatus including a DC bias pulse generating means and an adding means for adding an RF pulse and a DC bias pulse will be described.

  FIG. 13 is a block diagram of a circuit configuration of the intra-body-cavity insertion type ultrasonic diagnostic apparatus according to the present embodiment. FIG. 13 shows a structure in which a DC bias applying means 70 is provided between the piezoelectric transformer secondary electrode 20d and the switch terminal 12a in FIG.

  FIG. 14 shows details of the DC bias applying means 70 of FIG. FIG. 15 shows the waveform of each signal in the intracorporeal ultrasound diagnostic apparatus of FIG. The DC bias applying unit 70 includes an adder 71 and a rectifier 72.

  First, the cable transmission signal Sg1 is input to the piezoelectric transformer primary side electrode 20b of the piezoelectric transformer 20 (for example, a lithium niobate single crystal substrate) (see FIG. 15A). Then, as described in the first embodiment, a lateral effect piezoelectric vibration is caused by a high voltage signal applied between the piezoelectric transformer primary electrode 20b and the ground electrode 20c of the piezoelectric transformer 20, and the thickness direction polarization 77 is As a result, it is converted into a longitudinal effect vibration, and as a result, a high voltage AC signal 73 is generated at the electrode 20d.

  Then, an RF pulse 73 that is a high voltage signal is output from the piezoelectric transformer secondary electrode 20d. The high-voltage RF pulse 73 output from the piezoelectric transformer secondary electrode 20 d is input to the DC bias applying means 70.

  The RF pulse 73 is branched into two in the DC bias applying means 70. One of the branched RF pulses 74 (= 73) (see FIG. 15B) is input to the adder 71. The other branched RF pulse passes through the rectifier 72 to become a DC bias pulse (see FIG. 15C) 75 and is input to the adder 71. In the adder 71, the RF pulse 74 and the DC bias pulse 75 are added and output as a transducer drive signal Sg2 (see FIG. 15D). Note that 80 in FIG. 15D indicates a DC bias level.

  As described above, when a DC high voltage signal is output from the high voltage generating means 7, both the high voltage DC signal and the high voltage AC signal are output to the adder 71 at substantially the same timing in the high voltage generating means 7. . This is because both signals are easily superimposed. Specifically, when a DC high voltage signal is output from the high voltage generation means 7, the generation period of the DC output signal 75 output from the rectifier 72 is the same as the generation period of the AC output signal 74, or the AC output signal 74 is set so as to be longer than the generation period of 74, so that both signals are easily superimposed.

  That is, in FIG. 15, in order to make the pulse width of the DC output signal 75 longer than the pulse width of the AC output signal 74, the DC output signal 75 is output first and then the AC output signal 74 is superimposed. After the output of 74 is finished, the output of the DC output signal 75 is finished.

  More specifically, a trigger signal is generated at the rising timing of the DC bias pulse, and an RF pulse is generated with the trigger signal after the set delay time has elapsed. If this delay time is set too long, the RF pulse deviates from the DC bias pulse (does not overlap), so an optimum delay time is set. Therefore, the adder 71 includes such a preliminary processing function (delay function).

  The DC output signal generation period should not exceed 10 μsec. This is because if the pulse width of the DC bias pulse is 10 μsec or more, even if there is an echo signal in the immediate vicinity, it will be superimposed on the transmission signal, the S / N of detection will be reduced, and a diagnostic image of the area close to the transducer It is because it becomes impossible to obtain.

  In addition, the cMUT may be damaged if the high voltage DC output signal rises and falls abruptly. In order to prevent this, the rise and fall of the high voltage DC output signal are slowed down. That is, since the steep rise and fall have a high frequency component, this high frequency component is bypassed by connecting a capacitor in parallel to the output terminal, and the rise and fall are blunted.

In this embodiment, the case where a piezoelectric transformer is used has been described, but it may be used for an electromagnetic transformer.
Since the broadband characteristic of the cMUT depends on the DC bias, the broadband characteristic can be obtained by generating the DC bias as described above, and ultrasonic diagnosis using harmonic imaging can be performed. In the present embodiment, the components shown in FIGS. 13 and 14, for example, SW12, rectifiers 11 and 72, adder 71, and the delay circuit (not shown) are formed on or inside the Si substrate on which cMUT 6b is formed. The charge amplifier 60 can be integrated (integrated) by using a semiconductor process, thereby realizing further downsizing and a more preferable form as an ultrasonic transducer for insertion into a body cavity.

Example 4
FIG. 16 shows a block diagram of a circuit configuration of the intra-body-cavity ultrasonic diagnostic apparatus according to the present embodiment. In the figure, a high frequency oscillator 90 for generating an AC signal to be applied to the input side of the booster 7a is further provided in the circuit of FIG. This is a device in which a piezoelectric transformer is operated by an AC signal, and has a configuration intended for DC voltage operation. That is, the signal 91 is a DC voltage signal, and a high-frequency oscillation circuit 90 is used as means for converting the signal 91 into an AC signal 92.

  FIG. 17 shows the waveform of each signal in the body cavity insertion type ultrasonic diagnostic apparatus of FIG. A DC pulse 91 (see FIG. 17A) is transmitted as the cable transmission signal Sg1 and input to the high-frequency oscillator 90. The high-frequency oscillator 90 increases the frequency of the DC pulse 91 and converts it into a burst wave 92 (see FIG. 17B).

  The burst wave 92 is input to the piezoelectric transformer primary electrode 20b of the piezoelectric transformer 20 (for example, a lithium niobate single crystal substrate), and the subsequent steps are the same as in the third embodiment (FIG. 17B is shown in FIG. 15). Fig. 17 (c) corresponds to Fig. 15 (b), Fig. 17 (d) corresponds to Fig. 15 (c), Fig. 17 (e) corresponds to Fig. 15 (d). ).

  By doing so, the cable transmission signal Sg1 has a low frequency, so there is no cable signal loss, and the cable transmission signal Sg1 is less likely to be affected by the transfer of noise to the outside or from the outside. In this embodiment, the case where a piezoelectric transformer is used has been described, but it may be used for an electromagnetic transformer.

  FIG. 18 shows a block diagram of a circuit configuration of the body cavity insertion portion using the array type ultrasonic transducer in the present embodiment. A capacitive ultrasonic transducer array 100 and a plurality of transducer elements (6b-1, 6b-2, 6b-3,..., 6b-n) of FIG. 16 are arranged in an array. .

1 is a block diagram of a circuit configuration of a body cavity insertion type ultrasonic diagnostic apparatus using a piezoelectric vibrator as an ultrasonic vibrator in the first embodiment. FIG. 1 is a block diagram of a circuit configuration of a body cavity insertion type ultrasonic diagnostic apparatus using an electromagnetic step-up transformer as a step-up unit in a first mode for embodying the present invention (Example 1); FIG. 1 is a block diagram of a circuit configuration of a body cavity insertion type ultrasonic diagnostic apparatus using a piezoelectric step-up transformer as a step-up unit in the first embodiment (Example 2). FIG. An example of the structure of p-MUT in 1st Embodiment is shown. The structure of a Rosen type piezoelectric transformer is shown. The piezoelectric transformer using the lithium niobate in 1st Embodiment (Example 2) is shown. The vibration displacement when observed from the side surface direction of the lithium niobate single crystal substrate 31 of FIG. 6 is shown. It is the modification (the 1) of FIG. It is the modification (the 2) of FIG. The block diagram of the intracorporeal-insertion type ultrasonic diagnostic apparatus which used the capacitive ultrasonic transducer | vibrator (cMUT) as an ultrasonic transducer | vibrator in 2nd Embodiment is shown. The block diagram of the circuit structure of the intracorporeal-insertion type ultrasonic diagnostic apparatus which uses the electromagnetic type | mold pressure | voltage rise transformer as a pressure | voltage rise means in 2nd Embodiment (Example 1) is shown. The block diagram of the circuit structure of the intracorporeal-insertion-type ultrasonic diagnostic apparatus which uses the piezoelectric type step-up transformer as a pressure | voltage rise means in 2nd Embodiment (Example 2) is shown. The block diagram of the circuit structure of the body-cavity insertion type ultrasonic diagnostic apparatus in 2nd Embodiment (Example 3) is shown. The details of the DC bias applying means 70 of FIG. 13 are shown. The waveform of each signal in the body cavity insertion type ultrasonic diagnostic apparatus of FIG. 14 is shown. The block diagram of the circuit structure of the body cavity insertion type ultrasonic diagnostic apparatus in 2nd Embodiment (Example 4) is shown. The waveform of each signal in the body cavity insertion type ultrasonic diagnostic apparatus of FIG. 16 is shown. The block diagram of the circuit structure of the insertion part in a body cavity using the array type | mold ultrasonic transducer | vibrator in 2nd Embodiment (Example 4) is shown. An example of a conventional cMUT is shown. An example (part 1) of a conventional control circuit using a drive circuit for a piezoelectric ultrasonic transducer is shown. An example (part 2) of a conventional control circuit using a drive circuit for a piezoelectric ultrasonic transducer is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Intracorporeal-insertion type ultrasonic diagnostic apparatus 2 Insertion part 3 Ultrasonic probe 4 Bending part and flexible tube part 5 Observation apparatus 6a Piezoelectric vibrator 6a-1 Upper electrode 6a-2 Membrane 6a-3 Cavity 6a-4 Silicon substrate 6a -5 Lower electrode 6a-6 Piezoelectric film 6b cMUT
7 High voltage generating means 7a Boosting means 8 Coaxial cable 8
8a Core wire 8b Shield wire 10 Step-up transformer 10a Step-up transformer primary side coil 10b, 10c Step-up transformer secondary side coil 11 Rectifier 12 Switch 12a, 12b, 12c, 12d Switch terminal 20 Piezoelectric transformer 20a Piezoelectric vibrator 20b Piezoelectric transformer primary side Electrode 20c Ground electrode 20d Piezoelectric transformer secondary electrode 21 Resistor (DC resistance)
60 charge amplifier 70 DC bias applying means 71 adder 72 rectifier 90 high frequency oscillator

Claims (26)

An ultrasonic transducer for transmitting and receiving ultrasonic waves;
A high voltage generating means for generating a high voltage based on the drive signal when a drive signal for driving the ultrasonic vibrator is input, and applying the high voltage to the ultrasonic vibrator;
The ultrasonic probe is characterized by being arranged close to each other at its tip.   The ultrasonic probe according to claim 1, wherein the ultrasonic transducer is a capacitive ultrasonic transducer (cMUT) manufactured using a micromachine manufacturing process.   The ultrasonic probe according to claim 1, wherein the ultrasonic transducer is a piezoelectric transducer (p-MUT) manufactured using a micromachine manufacturing process.   The ultrasonic probe according to claim 1, wherein, when the driving signal is a DC low voltage, the high voltage generating unit outputs a DC high voltage based on the driving signal.   2. The ultrasonic probe according to claim 1, wherein when the drive signal is a direct current low voltage, the high voltage generation unit outputs an alternating current high voltage based on the drive signal.   The ultrasonic probe according to claim 1, wherein when the drive signal is an AC low voltage, the high voltage generator outputs a DC high voltage based on the drive signal.   2. The ultrasonic probe according to claim 1, wherein, when the drive signal is an AC low voltage, the high voltage generating unit outputs an AC high voltage based on the drive signal.   The ultrasonic probe according to claim 5 or 7, wherein a frequency of the drive signal of the AC high voltage is substantially equal to a resonance frequency of the ultrasonic transducer.   The ultrasonic probe according to claim 5 or 7, wherein the AC high voltage is a burst wave.   The ultrasonic probe according to claim 1, wherein the high voltage generating unit includes a boosting unit that boosts the voltage of the drive signal.   The ultrasonic probe according to claim 10, wherein the boosting unit is an electromagnetic transformer.   The ultrasonic probe according to claim 10, wherein the boosting unit is a piezoelectric transformer.   The ultrasonic probe according to claim 12, wherein the piezoelectric transformer is a Rosen type.   The ultrasonic probe according to claim 12, wherein the piezoelectric transformer is made of lithium niobate. The high voltage generating means further includes:
The ultrasonic probe according to claim 10, further comprising: an oscillating unit that converts the driving signal into an AC signal and outputs the AC signal to the boosting unit when the driving signal is a DC signal. The high voltage generating means further includes:
The ultrasonic probe according to claim 10, further comprising: a DC bias applying unit that applies a DC bias voltage to the AC high voltage output from the boosting unit. The DC bias applying means includes a branching means for branching the AC high voltage output from the boosting means into a first AC high voltage and a second AC high voltage;
DC conversion means for converting the first AC high voltage to DC;
Adding means for adding the DC voltage output from the DC conversion means and the second AC high voltage;
The ultrasonic probe according to claim 16, comprising:   The ultrasonic probe according to claim 17, wherein the adding means superimposes the second AC high voltage on a period in which the DC voltage is generated.   The ultrasonic probe according to claim 18, wherein the period during which the DC voltage is generated does not exceed 10 μsec.   The ultrasonic probe according to claim 17, wherein the adding means includes means for blunting rising and falling of the DC voltage.   The ultrasonic probe according to claim 3, wherein the p-MUT is formed on a silicon substrate, and a switch circuit and a rectifier are further provided on the silicon substrate.   The ultrasonic probe according to claim 2, wherein the cMUT is an electret condenser using an electret film.   The ultrasonic probe according to claim 2, wherein at least one of a step-up transformer, a switch circuit, a rectifier, and a charge amplifier can be formed on or inside the silicon substrate of the cMUT.   3. The ultrasonic probe according to claim 2, wherein a switch circuit, a rectifier, and a charge amplifier are integrated on or inside a silicon substrate constituting the cMUT using a semiconductor process.   3. The ultrasonic probe according to claim 2, wherein a switch circuit, a rectifier, an adder, a delay circuit, and a charge amplifier are integrated on or inside the silicon substrate on which the cMUT is formed using a semiconductor process. . An intracorporeal insertion type ultrasonic diagnostic apparatus comprising the ultrasonic probe according to any one of claims 1 to 25.