Determination method of voltage pulse for polarization, and ultrasonic diagnostic device

Abstract

To specify a voltage pulse capable of enhancing polarization of an ultrasonic transducer.SOLUTION: A voltage pulse is applied to an ultrasonic transducer 10. A voltage waveform and a current waveform when the voltage pulse is applied to the ultrasonic transducer 10 are measured. A charge waveform is calculated on the basis of the current waveform. Whether the voltage pulse is a voltage pulse enhancing polarization of the ultrasonic transducer 10 is determined on the basis of a code of a value of a charge indicated by the charge waveform.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method for determining a polarization voltage pulse and an ultrasound diagnostic device. [Background technology]

[0002] When the polarization of an ultrasonic transducer deteriorates, the polarization may be strengthened by applying a voltage pulse to the ultrasonic transducer from a pulse generating circuit mounted on the ultrasonic diagnostic device (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-605 A [Patent Document 2] Patent Publication No. 2022-40175 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to generate a voltage pulse only for strengthening polarization (i.e., a voltage pulse dedicated to repolarization) from a pulse generating circuit mounted on an ultrasonic diagnostic device, it is necessary to apply a special design or the like to the pulse generating circuit for that purpose. Or, it is necessary to mount a special pulse generating circuit for generating a voltage pulse dedicated to repolarization on the ultrasonic diagnostic device. For example, when a voltage pulse having a frequency band different from the frequency band for ultrasonic diagnosis (e.g., a low-frequency voltage pulse) is applied to an ultrasonic transducer, it is necessary to perform a special design for that purpose or provide a special pulse generating circuit on the ultrasonic diagnostic device.

[0005] It is conceivable to strengthen the polarization of an ultrasonic transducer by applying a voltage pulse having a frequency band for ultrasonic diagnosis to the ultrasonic transducer without using a voltage pulse dedicated to repolarization or a special pulse generating circuit, which eliminates the need for special design or the need to install a special pulse generating circuit in the ultrasonic diagnostic device.

[0006] However, in general, an ultrasonic diagnostic device can output a plurality of types of voltage pulses, so it is difficult for a user (e.g., an examiner who performs an ultrasonic examination using the ultrasonic diagnostic device, an operator who performs maintenance on the ultrasonic diagnostic device, etc.) to identify which of the plurality of types of voltage pulses is capable of strengthening the polarization of an ultrasonic transducer.

[0007] An objective of this disclosure is to identify voltage pulses that can enhance the polarization of an ultrasound transducer. [Means for solving the problem]

[0008] One aspect of the present disclosure is a method for determining a polarization voltage pulse, comprising the steps of: applying a voltage pulse to an ultrasonic transducer; measuring a voltage waveform and a current waveform when the voltage pulse is applied to the ultrasonic transducer; calculating a charge waveform based on the current waveform; and determining whether or not the voltage pulse is a voltage pulse that strengthens the polarization of the ultrasonic transducer based on the sign of the charge value indicated by the charge waveform.

[0009] When the sign of the charge value indicated by the charge waveform is the same as the sign of the residual polarization value of the ultrasonic transducer, it may be determined that the voltage pulse is a voltage pulse that strengthens the polarization of the ultrasonic transducer.

[0010] The voltage pulse applied to the ultrasonic transducer is a voltage pulse selected from one or more voltage pulses that an ultrasonic diagnostic device can output, and the ultrasonic diagnostic device may be a device to which an ultrasonic probe including the ultrasonic transducer is connected.

[0011] The frequency characteristic of the voltage pulse may overlap with the frequency characteristic of a voltage pulse applied to the ultrasonic transducer when ultrasonic diagnosis is performed by the ultrasonic diagnostic device.

[0012] One aspect of the present disclosure is an ultrasonic diagnostic device including an ultrasonic transducer and a transmission circuit that applies a voltage pulse to the ultrasonic transducer to cause the ultrasonic transducer to output ultrasonic waves, characterized in that when performing polarization processing of the ultrasonic transducer, the transmission circuit applies, as a polarization voltage pulse to the ultrasonic transducer, a voltage pulse that is determined to strengthen the polarization of the ultrasonic transducer by the method for determining a polarization voltage pulse described in claim 3 or claim 4.

[0013] The transmission circuit may apply the polarization voltage pulse to the ultrasound transducer before an ultrasound diagnosis.

[0014] The transmission circuit may apply the polarizing voltage pulse to the ultrasonic transducer until polarization is saturated.

[0015] A state of polarization of the ultrasonic transducer may be determined based on the voltage and current applied to the ultrasonic transducer. Effect of the Invention

[0016] According to the present disclosure, voltage pulses capable of enhancing the polarization of an ultrasound transducer can be identified. [Brief description of the drawings]

[0017] [Figure 1] 1 is a block diagram showing a configuration of a determination system according to a first embodiment. [Diagram 2] 1 is a block diagram showing a configuration of a determination device according to a first embodiment. [Diagram 3] FIG. 4 is a graph showing the measurement results according to the first embodiment. [Figure 4] FIG. 13 is a graph showing a verification result according to the first embodiment. [Diagram 5] FIG. 11 is a graph showing the measurement results according to the second embodiment. [Figure 6] FIG. 4 is a diagram showing the relationship between a frequency band and a frequency spectrum of a voltage waveform. [Figure 7]FIG. 11 is a graph showing a verification result according to the second embodiment. [Figure 8] FIG. 11 is a block diagram showing the configuration of an ultrasound diagnostic apparatus according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] First Embodiment 1 shows an example of the configuration of a determination system according to the first embodiment. The determination system according to the first embodiment determines whether or not a pulsed voltage applied to an ultrasonic transducer 10 strengthens the polarization of the ultrasonic transducer 10.

[0019] For example, the determination system according to the first embodiment includes an ultrasonic transducer 10, a signal generator 12, a power amplifier 14, an oscilloscope 16, and a determination device 18.

[0020] The ultrasonic transducer 10 is an element mounted on an ultrasonic probe. For example, the ultrasonic transducer 10 is made of a single crystal vibrator, which is a piezoelectric element. Usually, the ultrasonic transducer 10 is used in a polarized state.

[0021] For example, the single crystal oscillator may be, but is not limited to, quartz, lithium niobate, lead magnesium niobate, lead zinc niobate, lead indium niobate, lead titanate, lead magnesium niobate-lead titanate, lead zinc niobate-lead titanate, lithium tantalate, langasite, or zinc oxide.

[0022] An ultrasonic transducer made of a single crystal transducer is capable of receiving ultrasonic waves with high sensitivity. However, as the operating time of the ultrasonic diagnostic device increases, a depolarization phenomenon may occur in which the degree of polarization decreases. When the depolarization phenomenon occurs, the receiving sensitivity of the ultrasonic transducer 10 decreases, and as a result, the image quality of the ultrasonic image may decrease.

[0023] The signal generator 12 is a circuit that generates a pulsed voltage (hereinafter referred to as a "voltage pulse"). The voltage pulse generated by the signal generator 12 is amplified by a power amplifier 14 and applied to the ultrasonic transducer 10. For example, the signal generator 12 and the power amplifier 14 are connected by a coaxial cable.

[0024] The voltage pulse generated by the signal generator 12 may be a voltage pulse selected from one or more voltage pulses that can be output by an ultrasonic diagnostic device. The ultrasonic diagnostic device is a device to which an ultrasonic probe including an ultrasonic transducer 10 is connected.

[0025] All or part of the frequency band of the voltage pulse generated by the signal generator 12 may overlap with the frequency band of the voltage pulse applied to the ultrasonic transducer 10 when ultrasonic diagnosis is performed by the ultrasonic diagnostic device. Hereinafter, the voltage pulse applied to the ultrasonic transducer 10 when ultrasonic diagnosis is performed by the ultrasonic diagnostic device is referred to as a "diagnostic voltage pulse."

[0026] The power amplifier 14 and the ultrasonic transducer 10 are connected to each other by a wiring 20. One end of a voltage probe 22 and one end of a current probe 24 are connected to the wiring 20. The other end of the voltage probe 22 and the other end of the current probe 24 are connected to an oscilloscope 16.

[0027] The oscilloscope 16 measures the voltage waveform and the current waveform when a voltage pulse is applied to the ultrasonic transducer 10. The measurement results are output from the oscilloscope 16 to a determination device 18.

[0028] The determination device 18 determines, based on the measurement results of the oscilloscope 16, whether or not the voltage pulse applied to the ultrasonic transducer 10 is a voltage pulse that strengthens the polarization of the ultrasonic transducer 10.

[0029] 2 shows an example of the configuration of the determination device 18. For example, the determination device 18 includes a calculation unit 26 and a determination unit .

[0030] The calculation unit 26 calculates the charge waveform based on the current waveform measured by the oscilloscope 16. For example, the calculation unit 26 calculates the charge waveform Q(t) by time-integrating the current waveform according to the following equation (1).

number

[0031] The judgment unit 28 judges whether or not the voltage pulse applied to the ultrasonic transducer 10 is a voltage pulse that strengthens the polarization of the ultrasonic transducer 10 based on the sign (i.e., plus (+), minus (-)) of the charge value indicated by the charge waveform Q(t) calculated by the calculation unit 26.

[0032] For example, the signal generator 12 applies a voltage pulse to the ultrasonic transducer 10, and then does not apply the voltage pulse to the ultrasonic transducer 10. The determination unit 28 determines whether or not the voltage pulse applied to the ultrasonic transducer 10 is a voltage pulse that strengthens the polarization of the ultrasonic transducer 10, based on the charge waveform Q(t) calculated from the current waveform measured after the voltage pulse is no longer applied to the ultrasonic transducer 10.

[0033] For example, if the sign of the charge value indicated by the charge waveform Q(t) is the same as the sign of the residual polarization value of the ultrasonic transducer 10, the judgment unit 28 judges that the voltage pulse applied to the ultrasonic transducer 10 is a voltage pulse that strengthens the polarization of the ultrasonic transducer 10.

[0034] If the sign of the charge value indicated by the charge waveform Q(t) is different from the sign of the residual polarization value of the ultrasonic transducer 10, the judgment unit 28 judges that the voltage pulse applied to the ultrasonic transducer 10 is a voltage pulse that does not strengthen the polarization of the ultrasonic transducer 10.

[0035] The sign of the residual polarization value of the ultrasonic transducer 10 is known in advance. For example, the ultrasonic transducer 10 is designed and manufactured so that the sign of the residual polarization value is negative (-). Of course, the ultrasonic transducer 10 may be designed and manufactured so that the sign of the residual polarization value is positive (+).

[0036] For example, information indicating the sign of the residual polarization value of the ultrasonic transducer 10 is stored in advance in a storage device (e.g., a memory, a hard disk drive, etc.) of the determination device 18. Based on the information stored in the memory, the determination device 18 determines whether or not the voltage pulse applied to the ultrasonic transducer 10 is a voltage pulse that strengthens the polarization of the ultrasonic transducer 10.

[0037] The determination device 18 outputs the determination result. For example, the determination device 18 may display information indicating the determination result on a display, may transmit the information indicating the determination result to an external device (for example, a personal computer, a server, a smartphone, etc.), or may store the information indicating the determination result in a storage device.

[0038] For example, an ultrasonic diagnostic device has a function of applying several to several tens of different types of diagnostic voltage pulses to an ultrasonic transducer 10 included in an ultrasonic probe. In this case, the signal generator 12 applies to the ultrasonic transducer 10 a voltage pulse selected from a plurality of voltage pulses (e.g., a plurality of diagnostic voltage pulses) that can be applied by the ultrasonic diagnostic device.

[0039] For example, the signal generator 12 applies a voltage pulse selected by a user from the plurality of voltage pulses to the ultrasonic transducer 10. This determines whether the voltage pulse selected by the user is a voltage pulse that strengthens the polarization of the ultrasonic transducer 10.

[0040] As another example, the signal generator 12 sequentially applies a plurality of different voltage pulses to the ultrasonic transducer 10. For each voltage pulse, the determination device 18 determines whether the voltage pulse is a voltage pulse that strengthens the polarization of the ultrasonic transducer 10.

[0041] For example, the calculation unit 26 and the determination unit 28 can be realized by using hardware resources such as a processor and an electronic circuit, and a device such as a memory may be used in the realization as necessary. The calculation unit 26 and the determination unit 28 may be realized by, for example, a computer. That is, the calculation unit 26 and the determination unit 28 may be realized in whole or in part by cooperation between hardware resources such as a CPU (Central Processing Unit) and a memory provided in a computer and software (program) that specifies the operation of the CPU and the like. The program is stored in a storage device via a recording medium such as a CD or a DVD, or via a communication path such as a network. As another example, the calculation unit 26 and the determination unit 28 may be realized by a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), or an FPGA (Field Programmable Gate Array), or the like. Of course, a GPU (Graphics Processing Unit), or the like, may be used. The determination device 18 may be a single device, or may be configured by multiple different devices. That is, the functions of the calculation unit 26 and the determination unit 28 may be realized by a single device, or may be realized by multiple different devices.

[0042] The method for determining the polarization voltage pulse according to the first embodiment will be described below.

[0043] First, the signal generator 12 applies a voltage pulse to the ultrasonic transducer 10 via the power amplifier 14. The signal generator 12 may apply a voltage pulse selected by a user from among a plurality of different voltage pulses (e.g., a plurality of diagnostic voltage pulses) to the ultrasonic transducer 10, or may apply a voltage pulse automatically selected from a plurality of different voltage pulses (e.g., a plurality of diagnostic voltage pulses) to the ultrasonic transducer 10.

[0044] When a voltage pulse is applied to the ultrasonic transducer 10 , the voltage and current waveforms are measured by the oscilloscope 16 .

[0045] The calculation section 26 calculates the charge waveform Q(t) based on the measured current waveform.

[0046] The determination unit 28 determines whether or not the voltage pulse applied to the ultrasonic transducer 10 is a voltage pulse that strengthens the polarization of the ultrasonic transducer 10 based on the sign of the charge value indicated by the charge waveform Q(t) calculated by the calculation unit 26. Specifically, when the sign of the charge value indicated by the charge waveform Q(t) is the same as the sign of the residual polarization value of the ultrasonic transducer 10, the determination unit 28 determines that the voltage pulse applied to the ultrasonic transducer 10 is a voltage pulse that strengthens the polarization of the ultrasonic transducer 10. When the sign of the charge value indicated by the charge waveform Q(t) is different from the sign of the residual polarization value of the ultrasonic transducer 10, the determination unit 28 determines that the voltage pulse applied to the ultrasonic transducer 10 is a voltage pulse that does not strengthen the polarization of the ultrasonic transducer 10.

[0047] Examples will be described below.

[0048] Example 1 Fig. 3 shows a graph illustrating the measurement results according to Example 1. A voltage waveform and a charge waveform are shown in Fig. 3. The horizontal axis indicates time. The vertical axis on the left indicates the value of the voltage pulse applied to the ultrasonic transducer 10. The vertical axis on the right indicates the value of the charge calculated from the current waveform.

[0049] Voltage waveforms 30 and 32 are voltage waveforms measured by applying different voltage pulses to ultrasonic transducer 10. Voltage waveform 30 is a voltage waveform measured by applying voltage pulse A to ultrasonic transducer 10. Voltage waveform 32 is a voltage waveform measured by applying voltage pulse B to ultrasonic transducer 10. Voltage pulse B is different from voltage pulse A.

[0050] For ease of explanation, the current waveform measured by applying voltage pulse A to ultrasonic transducer 10 is referred to as "current waveform A." The current waveform measured by applying voltage pulse B to ultrasonic transducer 10 is referred to as "current waveform B."

[0051] Charge waveform 34 is a charge waveform calculated based on current waveform A. Charge waveform 36 is a charge waveform calculated based on current waveform B.

[0052] By applying a voltage pulse A to the ultrasonic transducer 10, the voltage waveform 30 and the current waveform A are measured, and a charge waveform 34 is calculated. By applying a voltage pulse B to the ultrasonic transducer 10, the voltage waveform 32 and the current waveform B are measured, and a charge waveform 36 is calculated.

[0053] For example, the sign of the residual polarization value of the ultrasonic transducer 10 is negative (-). In this case, a voltage pulse for which a voltage waveform for Q(t)<0 is measured is a voltage pulse that strengthens the polarization of the ultrasonic transducer 10.

[0054] As shown in FIG. 3, a voltage pulse A is applied to the ultrasonic transducer 10, and then the voltage pulse is not applied to the ultrasonic transducer 10. The same is true for the voltage pulse B. While the voltage pulse is applied to the ultrasonic transducer 10, the charge value fluctuates greatly, and the sign of the charge value is not constant. After the voltage pulse is no longer applied to the ultrasonic transducer 10, the charge value fluctuates less, and the sign of the charge value becomes constant. The determination unit 28 determines whether the voltage pulse applied to the ultrasonic transducer 10 is a voltage pulse that strengthens the polarization of the ultrasonic transducer 10, based on the constant sign.

[0055] In the example shown in FIG. 3, after the voltage pulse is no longer applied to the ultrasonic transducer 10, the value indicated by the charge waveform 34 becomes negative (i.e., Q(t)<0). The value indicated by the charge waveform 36 becomes positive (i.e., Q(t)>0). Therefore, the voltage pulse A from which the charge waveform 34 and the voltage waveform 30 are obtained is a voltage pulse that strengthens the polarization of the ultrasonic transducer 10. The voltage pulse B from which the charge waveform 36 and the voltage waveform 32 are obtained is not a voltage pulse that strengthens the polarization of the ultrasonic transducer 10.

[0056] The determination unit 28 determines that the voltage pulse A is a voltage pulse that strengthens the polarization of the ultrasonic transducer 10, and determines that the voltage pulse B is not a voltage pulse that strengthens the polarization of the ultrasonic transducer 10.

[0057] As described above, based on the sign of the charge after the voltage pulse is applied to the ultrasonic transducer 10, it is possible to determine whether or not the voltage pulse applied to the ultrasonic transducer 10 is a voltage pulse that strengthens the polarization of the ultrasonic transducer 10.

[0058] For example, the ultrasonic diagnostic device has a function of outputting voltage pulses A, B, . . . , Z that are different from each other. The signal generator 12 applies each of the voltage pulses A, B, . . . , Z to the ultrasonic transducer 10 separately. As a result, the voltage waveform and the current waveform are measured for each voltage pulse, and the charge waveform is calculated. The determination device 18 determines whether or not the voltage pulse applied to the ultrasonic transducer 10 is a voltage pulse that strengthens the polarization of the ultrasonic transducer 10 for each voltage pulse. As a result, it is possible to identify the voltage pulse that strengthens the polarization of the ultrasonic transducer 10 among the voltage pulses A, B, . . . , Z. Even if the user does not know which voltage pulse among the voltage pulses A, B, . . . , Z is the voltage pulse that strengthens the polarization of the ultrasonic transducer 10, it is possible to identify the voltage pulse that strengthens the polarization of the ultrasonic transducer 10.

[0059] 4 shows a graph illustrating the verification results according to Example 1. The horizontal axis represents frequency, the vertical axis on the left represents electrical impedance, and the vertical axis on the right represents phase.

[0060] Reference numeral 38 denotes the initial electrical impedance of the ultrasonic transducer 10. Reference numeral 40 denotes the electrical impedance after a voltage pulse that weakens the polarization is applied to the ultrasonic transducer 10. After the voltage pulse that weakens the polarization is applied to the ultrasonic transducer 10, a voltage pulse that strengthens the polarization is applied to the ultrasonic transducer 10. Reference numeral 42 denotes the electrical impedance after a voltage pulse that strengthens the polarization is applied to the ultrasonic transducer 10. For example, a voltage pulse that is determined by the determination device 18 to be a voltage pulse that strengthens the polarization is applied to the ultrasonic transducer 10.

[0061] Reference numeral 44 denotes the initial phase of the ultrasonic transducer 10. Reference numeral 46 denotes the phase after a polarization weakening voltage pulse is applied to the ultrasonic transducer 10. Reference numeral 48 denotes the phase after a polarization strengthening voltage pulse is applied.

[0062] As shown by reference numerals 40 and 46, when a voltage pulse that weakens the polarization was applied to the ultrasonic transducer 10, the characteristics of the ultrasonic transducer 10 deteriorated. By applying a voltage pulse that strengthens the polarization to the ultrasonic transducer 10 with deteriorated characteristics, the characteristics of the ultrasonic transducer 10 were restored, as shown by reference numerals 42 and 48. In this way, by applying a voltage pulse that is determined by the determination device 18 to be a voltage pulse that strengthens the polarization to the ultrasonic transducer 10, the characteristics of the ultrasonic transducer 10 can be restored.

[0063] Example 2 Fig. 5 shows a graph illustrating the measurement results according to Example 2. A voltage waveform and a charge waveform are shown in Fig. 5. The horizontal axis indicates time. The vertical axis on the left indicates the value of the voltage pulse applied to the ultrasonic transducer 10. The vertical axis on the right indicates the value of the charge calculated from the current waveform.

[0064] Voltage waveform 50 is a voltage waveform measured by applying a voltage pulse according to Example 2 of the first embodiment to ultrasonic transducer 10. The voltage pulse according to Example 2 is referred to as a "voltage pulse α." For example, voltage pulse α is a voltage pulse determined by determination device 18 to be a voltage pulse that strengthens the charge of ultrasonic transducer 10.

[0065] For convenience of explanation, the current waveform measured by applying a voltage pulse α to the ultrasonic transducer 10 is referred to as a “current waveform α.” The charge waveform 52 is a charge waveform calculated based on the current waveform α.

[0066] Voltage waveform 54 is a voltage waveform measured by applying a voltage pulse according to the comparative example to ultrasonic transducer 10. The voltage pulse according to the comparative example is referred to as a "voltage pulse β." Voltage pulse β is a voltage pulse that strengthens the charge of ultrasonic transducer 10.

[0067] For ease of explanation, the current waveform measured by applying a voltage pulse β to the ultrasonic transducer 10 is referred to as a “current waveform β.” The charge waveform 56 is a charge waveform calculated based on the current waveform β.

[0068] Figure 6 shows the relationship between the frequency band and the frequency spectrum of the voltage waveform. The horizontal axis represents frequency, and the vertical axis represents sound pressure.

[0069] Reference numeral 58 indicates the frequency characteristic of the ultrasonic probe. Reference numeral 59 indicates an example of the frequency characteristic of a diagnostic voltage pulse. The diagnostic voltage pulse is a voltage pulse applied to an ultrasonic transducer (e.g., ultrasonic transducer 10) when ultrasonic diagnosis is performed by an ultrasonic diagnostic device. The frequency band of the diagnostic voltage pulse is the frequency band of the voltage pulse applied to the ultrasonic transducer 10 when ultrasonic diagnosis is performed.

[0070] Reference numeral 60 indicates the frequency characteristic of the voltage pulse α applied to the ultrasonic transducer 10 according to the second embodiment. As reference numeral 60 indicates, the frequency characteristic of the voltage pulse α at least partially overlaps with the frequency characteristic 58 of the ultrasonic probe. For example, the frequency characteristic of the voltage pulse α overlaps with the frequency characteristic 58 of the ultrasonic probe in a range of a level of -20 dB or more. Of course, this value is an example and may vary depending on the characteristics of the ultrasonic transducer 10. In addition, the voltage pulse α has the same frequency characteristic as the diagnostic voltage pulse 59. Therefore, the voltage pulse α can be applied to the ultrasonic transducer 10 by a circuit mounted on the ultrasonic diagnostic device.

[0071] Reference numeral 62 denotes a voltage pulse β applied to the ultrasonic transducer 10 according to the comparative example. As reference numeral 62 denotes, the frequency characteristic of the voltage pulse β does not overlap with the frequency characteristic of the diagnostic voltage pulse 59. In other words, the voltage pulse β has a frequency characteristic that is completely different from that of the diagnostic voltage pulse.

[0072] As described above, according to the second embodiment, the voltage pulse α having the same characteristics as the diagnostic voltage pulse is applied to the ultrasonic transducer 10, thereby strengthening the polarization of the ultrasonic transducer 10 and restoring the characteristics of the ultrasonic transducer 10. That is, according to the first embodiment, the characteristics of the ultrasonic transducer 10 can be restored by applying the voltage pulse α to the ultrasonic transducer 10 by a circuit mounted on the ultrasonic diagnostic device for applying a voltage pulse for ultrasonic diagnosis to the ultrasonic transducer 10. Therefore, the characteristics of the ultrasonic transducer 10 can be restored without providing a dedicated circuit (i.e., a circuit used only for strengthening the polarization) used only for restoring the characteristics of the ultrasonic transducer 10 separately in the ultrasonic diagnostic device.

[0073] In contrast, according to the comparative example, the polarization of the ultrasonic transducer 10 can be strengthened, but the voltage pulse β according to the comparative example has a completely different frequency characteristic from the diagnostic voltage pulse. Therefore, in order to restore the characteristics of the ultrasonic transducer 10 by the comparative example, it is necessary to separately provide a dedicated circuit used only for applying the voltage pulse β to the ultrasonic transducer 10 in the ultrasonic diagnostic device. In other words, since the voltage pulse β is a voltage pulse that is not applied by the circuit for applying the diagnostic voltage pulse to the ultrasonic transducer 10, it is necessary to provide a dedicated circuit for applying the voltage pulse β to the ultrasonic transducer 10 in the ultrasonic diagnostic device. According to the first embodiment, it is possible to restore the characteristics of the ultrasonic transducer 10 without using such a dedicated circuit.

[0074] 7 shows a graph illustrating the verification results according to Example 2. The horizontal axis represents frequency, the vertical axis on the left represents electrical impedance, and the vertical axis on the right represents phase.

[0075] Reference numeral 64 denotes the initial electrical impedance of the ultrasonic transducer 10. Reference numeral 66 denotes the electrical impedance after a voltage pulse that weakens the polarization is applied to the ultrasonic transducer 10. After a voltage pulse that weakens the polarization is applied to the ultrasonic transducer 10, a voltage pulse that strengthens the polarization is applied to the ultrasonic transducer 10. Reference numeral 68 denotes the electrical impedance after a voltage pulse α according to Example 2 is applied twice to the ultrasonic transducer 10. Reference numeral 70 denotes the electrical impedance after a voltage pulse α according to Example 2 is applied 20 times to the ultrasonic transducer 10.

[0076] Reference numeral 72 indicates the initial phase of the ultrasonic transducer 10. Reference numeral 74 indicates the phase after a polarization weakening voltage pulse is applied to the ultrasonic transducer 10. Reference numeral 76 indicates the electrical impedance after the voltage pulse α according to the second embodiment is applied twice to the ultrasonic transducer 10. Reference numeral 78 indicates the electrical impedance after the voltage pulse α according to the second embodiment is applied twenty times to the ultrasonic transducer 10.

[0077] As indicated by reference numerals 66 and 74, when a voltage pulse that weakens the polarization was applied to the ultrasonic transducer 10, the characteristics of the ultrasonic transducer 10 deteriorated. By applying a voltage pulse α that strengthens the polarization to the ultrasonic transducer 10 with deteriorated characteristics, the characteristics of the ultrasonic transducer 10 were restored. As indicated by reference numerals 70 and 78, for example, by applying the voltage pulse α 20 times to the ultrasonic transducer 10, the characteristics of the ultrasonic transducer 10 were restored. The number of times the voltage pulse is applied is merely an example, and the number of times may vary depending on the characteristics of the ultrasonic transducer 10, etc.

[0078] <Second embodiment> An ultrasonic diagnostic apparatus according to the second embodiment will be described with reference to Fig. 8. Fig. 8 shows an example of the configuration of an ultrasonic diagnostic apparatus 100 according to the second embodiment.

[0079] The ultrasound diagnostic device 100 transmits ultrasound waves into a subject using an ultrasound probe 102 and receives ultrasound waves reflected from within the subject, thereby generating an ultrasound image representing tissue within the subject.

[0080] The ultrasonic probe 102 is a device that transmits and receives ultrasonic waves. The ultrasonic probe 102 includes, for example, a 1D array transducer. The 1D array transducer is configured by arranging multiple ultrasonic transducers one-dimensionally. An ultrasonic beam is formed by the 1D array transducer, and the ultrasonic beam is repeatedly electronically scanned. As a result, a scanning plane is formed in the living body for each electronic scan. The ultrasonic probe 102 may include, instead of the 1D array transducer, a 2D array transducer formed by arranging multiple ultrasonic transducers two-dimensionally. As a scanning method, sector scanning, linear scanning, convex scanning, or the like is used. For example, the ultrasonic probe 102 includes an ultrasonic transducer 10.

[0081] The transmitting / receiving unit 104 functions as a transmitting beamformer and a receiving beamformer. During transmission, the transmitting / receiving unit 104 supplies a plurality of transmitting signals having a certain delay relationship to a plurality of ultrasonic transducers included in the ultrasonic probe 102. This forms an ultrasonic transmission beam. During reception, a reflected wave (RF signal) from inside the living body is received by the ultrasonic probe 102, and a plurality of receiving signals are output from the ultrasonic probe 102 to the transmitting / receiving unit 104. The transmitting / receiving unit 104 forms a receiving beam by applying a delay-and-add process to the plurality of receiving signals. The beam data is output to the signal processing unit 106. That is, the transmitting / receiving unit 104 performs a delay process on the receiving signal obtained from each ultrasonic transducer according to the delay process condition for each ultrasonic transducer, and forms a receiving beam by adding the plurality of receiving signals obtained from the plurality of ultrasonic transducers. The delay process condition is specified by the receiving delay data indicating the delay time. A receiving delay data set (i.e., a set of delay times) corresponding to the plurality of ultrasonic transducers is supplied from the control unit 114.

[0082] The signal processing unit 106 generates an ultrasound image (for example, a B-mode image) by applying signal processing such as detection, amplitude compression (amplitude conversion) such as logarithmic compression, and a conversion function (coordinate conversion function and interpolation processing function by a DSC (digital scan converter)), to the beam data output from the transmission / reception unit 104. The ultrasound image is not limited to a B-mode image, and may be a color Doppler image, a pulse Doppler image, a strain imaging image, a shear wave elastography image, or the like.

[0083] The display processing unit 108 overlays the necessary graphic data onto the ultrasound image, thereby generating a display image. The display image is output to the display unit 110, and one or more images are displayed side by side in a display format according to the display mode.

[0084] The display unit 110 is a display such as a liquid crystal display or an EL display. An ultrasound image such as a B-mode image is displayed on the display unit 110. The display unit 110 may be a device that combines a display and an operation unit 116. For example, a GUI (Graphic User Interface) may be realized by the display unit 110. Also, a user interface such as a touch panel may be realized by the display unit 110.

[0085] The storage unit 112 configures one or more storage areas for storing data. The storage unit 112 is, for example, a hard disk drive (HDD), a solid state drive (SSD), various types of memory (for example, RAM, DRAM, ROM, etc.), other storage devices (for example, optical disks, etc.), or a combination thereof. Images generated by imaging using the ultrasound diagnostic device 100, information indicating imaging conditions, information related to patients, etc. are stored in the storage unit 112.

[0086] The control unit 114 controls the operation of each unit of the ultrasound diagnostic apparatus 100 .

[0087] The operation unit 116 is a device that allows a user to input conditions and commands required for imaging to the ultrasound diagnostic apparatus 100. For example, the operation unit 116 is an operation panel, a switch, a button, a keyboard, a mouse, a trackball, or a joystick.

[0088] In the second embodiment, the transmitting / receiving unit 104 applies a polarization voltage pulse to an ultrasonic transducer (for example, the ultrasonic transducer 10) included in the ultrasonic probe 102. When the polarization of the ultrasonic transducer is weakened, applying the polarization voltage pulse to the ultrasonic transducer strengthens the polarization of the ultrasonic transducer, and the characteristics of the ultrasonic transducer are restored.

[0089] For example, before performing an ultrasound diagnosis on a subject, the transmission / reception unit 104 applies a polarization voltage pulse as a pre-pulse to the ultrasound transducer. For example, when a user such as an examiner instructs the start of an ultrasound diagnosis or the execution of a polarization process using the operation unit 116, the control unit 114 instructs the transmission / reception unit 104 to apply a polarization voltage pulse. Under the control of the control unit 114, the transmission / reception unit 104 applies the polarization voltage pulse to the ultrasound transducer.

[0090] For example, the number of times that the polarization voltage pulse is applied to the ultrasonic transducer is determined in advance, and the transmitting / receiving unit 104 applies the polarization voltage pulse to the ultrasonic transducer 10 that number of times under the control of the control unit 114. The number of times may be specified by the user.

[0091] After the application of the polarization voltage pulse to the ultrasonic transducer is completed, the transmitting / receiving unit 104 applies a voltage pulse for ultrasonic diagnosis to the ultrasonic transducer under the control of the control unit 114. This causes ultrasonic diagnosis to be performed. For example, an ultrasonic image such as a B-mode image is generated.

[0092] For example, the final sign of the polarization voltage pulse as a pre-pulse is a sign that ultimately strengthens the polarization, as shown in FIG.

[0093] The frequency characteristics of the polarization voltage pulse may overlap with the frequency characteristics of the voltage pulse applied to the ultrasonic transducer when ultrasonic diagnosis is performed by the ultrasonic diagnostic device 100. This makes it possible to strengthen the polarization of the ultrasonic transducer without providing the ultrasonic diagnostic device 100 with a dedicated circuit only for strengthening the polarization of the ultrasonic transducer.

[0094] The frequency band of the polarization voltage pulse may be a lower frequency band within the frequency band used for ultrasonic diagnosis. In this case, energy other than the energy converted into ultrasonic vibration is supplied to the ultrasonic transducer for polarization of the ferroelectric ultrasonic transducer, thereby enhancing the polarization of the ultrasonic transducer.

[0095] For example, the transmitting / receiving unit 104 applies a polarization voltage pulse to the ultrasonic transducer until the polarization of the ultrasonic transducer is saturated. In other words, the transmitting / receiving unit 104 applies a polarization voltage pulse to the ultrasonic transducer until the DE hysteresis loop of the ultrasonic transducer is saturated.

[0096] For example, the charge of the ultrasonic transducer is measured, and the control unit 114 determines the state of polarization of the ultrasonic transducer based on the measured charge. For example, the control unit 114 determines whether the polarization of the ultrasonic transducer is saturated or not based on the measured charge. The control unit 114 calculates the charge based on the voltage and current applied to the ultrasonic transducer, and determines whether the polarization of the ultrasonic transducer is saturated or not based on the calculated charge. The control unit 114 may calculate the charge based on the impedance of the ultrasonic transducer.

[0097] The determination method according to the first embodiment may or may not be applied to the second embodiment. That is, the transmitting / receiving unit 104 may apply a polarization voltage pulse determined by the determination method according to the first embodiment to the ultrasonic transducer, or may apply a polarization voltage pulse determined by a method different from the determination method according to the first embodiment to the ultrasonic transducer.

[0098] For example, the determination method according to the first embodiment is executed for an ultrasonic transducer (e.g., ultrasonic transducer 10) mounted on an ultrasonic probe 102. To explain in detail, the signal generator 12 applies a voltage pulse that can be applied by the ultrasonic diagnostic device 100 to the ultrasonic transducer, and the determination unit 28 determines whether or not the voltage pulse is a voltage pulse that strengthens the polarization of the ultrasonic transducer. The signal generator 12 selects one voltage pulse from among a plurality of different voltage pulses (e.g., a plurality of diagnostic voltage pulses) that can be applied by the ultrasonic diagnostic device 100, and applies the selected voltage pulse to the ultrasonic transducer. The determination unit 28 determines whether or not the selected voltage pulse strengthens the polarization of the ultrasonic transducer. The signal generator 12 applies different voltage pulses to the ultrasonic transducer, and the determination unit 28 determines whether or not the voltage pulse applied to the ultrasonic transducer is a voltage pulse that strengthens the polarization of the ultrasonic transducer. In this way, the determination unit 28 determines whether or not the voltage pulse applied to the ultrasonic transducer is a voltage pulse that strengthens the polarization of the ultrasonic transducer for each voltage pulse. This identifies a polarization voltage pulse that strengthens the polarization of the ultrasonic transducer. The ultrasonic transducer is mounted on the ultrasonic probe 102. Polarization voltage pulse information indicating the polarization voltage pulse that strengthens the polarization of the ultrasonic transducer is stored in the storage unit 112. The transmitting / receiving unit 104 applies the polarization voltage pulse indicated by the polarization voltage pulse information to the ultrasonic transducer. For example, before an ultrasonic diagnosis is performed, the transmitting / receiving unit 104 applies the polarization voltage pulse to the ultrasonic transducer as a pre-pulse. This allows the characteristics of the ultrasonic transducer to be restored before the ultrasonic diagnosis.

[0099] The determination device 18 may or may not be included in the ultrasound diagnostic device 100.

[0100] According to the second embodiment, it is possible to strengthen the polarization of the ultrasonic transducer and recover the characteristics of the ultrasonic transducer without equipping the ultrasonic diagnostic apparatus 100 with a dedicated circuit for applying a polarization voltage pulse to the ultrasonic transducer.

[0101] Furthermore, by applying the first embodiment to the second embodiment, it is possible to easily select a voltage pulse (i.e., a polarization voltage pulse) capable of strengthening the polarization of the ultrasonic transducer from among a plurality of different voltage pulses that can be applied by the ultrasonic diagnostic device 100, thereby strengthening the polarization of the ultrasonic transducer.

[0102] The signal processing unit 106, the display processing unit 108, and the control unit 114 can be realized by using hardware resources such as a processor and an electronic circuit, and a device such as a memory may be used as necessary in the realization. The signal processing unit 106, the display processing unit 108, and the control unit 114 may be realized by, for example, a computer. That is, the signal processing unit 106, the display processing unit 108, and the control unit 114 may be realized in whole or in part by cooperation between hardware resources such as a CPU and a memory provided in a computer and software (program) that defines the operation of the CPU and the like. The program is stored in the storage unit 112 of the ultrasound diagnostic device 100 or another storage device via a recording medium such as a CD or a DVD, or via a communication path such as a network. As another example, the signal processing unit 106, the display processing unit 108, and the control unit 114 may be realized by a DSP, an ASIC, an FPGA, or the like. Of course, a GPU or the like may be used. The ultrasound diagnostic device 100 may be a single device, or may be composed of multiple different devices. For example, the functions of the signal processing unit 106, the display processing unit 108, and the control unit 114 may be realized by a single device, or may be realized by a plurality of different devices. [Explanation of symbols]

[0103] 10 ultrasonic transducer, 12 signal generator, 18 determination device, 100 ultrasonic diagnostic device, 102 ultrasonic probe.

Claims

1. A voltage pulse is applied to the ultrasonic transducer. measuring a voltage waveform and a current waveform when the voltage pulse is applied to the ultrasonic transducer; Calculating a charge waveform based on the current waveform; determining whether or not the voltage pulse is a voltage pulse that strengthens the polarization of the ultrasonic transducer based on the sign of the charge value indicated by the charge waveform; A method for determining a polarization voltage pulse, comprising:

2. 2. The method for determining a polarization voltage pulse according to claim 1, When the sign of the charge value indicated by the charge waveform is the same as the sign of the residual polarization value of the ultrasonic transducer, the voltage pulse is determined to be a voltage pulse that strengthens the polarization of the ultrasonic transducer. A method for determining a polarization voltage pulse, comprising:

3. 3. The method for determining a polarization voltage pulse according to claim 2, The voltage pulse applied to the ultrasonic transducer is a voltage pulse selected from one or more voltage pulses that can be output by the ultrasonic diagnostic device, The ultrasonic diagnostic device is a device to which an ultrasonic probe including the ultrasonic transducer is connected. A method for determining a polarization voltage pulse, comprising:

4. 4. The method for determining a polarization voltage pulse according to claim 3, The frequency characteristic of the voltage pulse overlaps with the frequency characteristic of a voltage pulse applied to the ultrasonic transducer when ultrasonic diagnosis is performed by the ultrasonic diagnostic device. A method for determining a polarization voltage pulse, comprising:

5. An ultrasonic transducer; A transmission circuit that outputs ultrasonic waves from the ultrasonic transducer by applying a voltage pulse to the ultrasonic transducer; In an ultrasonic diagnostic apparatus including: When performing a polarization process on the ultrasonic transducer, the transmission circuit applies a voltage pulse determined to strengthen the polarization of the ultrasonic transducer by the method for determining a polarization voltage pulse according to claim 3 or 4 to the ultrasonic transducer as a polarization voltage pulse.

1. An ultrasonic diagnostic apparatus comprising:

6. 6. The ultrasonic diagnostic apparatus according to claim 5, The transmission circuit applies the polarization voltage pulse to the ultrasonic transducer before ultrasonic diagnosis.

1. An ultrasonic diagnostic apparatus comprising:

7. 7. The ultrasonic diagnostic apparatus according to claim 6, The transmission circuit applies the polarization voltage pulse to the ultrasonic transducer until the polarization is saturated.

1. An ultrasonic diagnostic apparatus comprising:

8. 8. The ultrasonic diagnostic apparatus according to claim 7, determining a state of polarization of the ultrasonic transducer based on a voltage and a current applied to the ultrasonic transducer; 1. An ultrasonic diagnostic apparatus comprising:

Images