JP2016077510A - Probe and information acquisition apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a probe and an information acquisition apparatus suited for harmonic imaging, etc.SOLUTION: A probe 101 is detachably connected to the main body 108 of an information acquisition apparatus which transmits an acoustic wave to a subject and receives the reflected wave to acquire information of the subject. The probe 101 comprises a transducer 102 for transmitting and receiving the acoustic wave. A variable frequency characteristic filter 103 of which frequency characteristics switch between signal transmission time and signal reception time is provided on an electric signal path 107 through which transmission signal and reception signal pass. The filter 103 at signal transmission allows the basic frequency component of the transmission signal to pass and blocks the harmonic component of the transmission signal. The filter 103 at signal reception blocks the basic frequency component of the reception signal and allows the harmonic component of the reception signal to pass.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a probe that transmits and receives an acoustic wave such as an ultrasonic wave, and a subject information acquisition apparatus including the probe. The acoustic wave is used as a term including a sound wave, an ultrasonic wave, a photoacoustic wave, and the like, but may be represented by an ultrasonic wave below.

  In an ultrasonic diagnostic apparatus, there is harmonic imaging in which an object is imaged using a harmonic component (harmonic) generated by an acoustic nonlinear phenomenon inside a living body. In harmonic imaging, harmonics are suppressed in transmission and only the fundamental frequency component (fundamental wave) is transmitted, and when receiving a reflected wave from the subject, only the harmonics are suppressed and imaged.

  In the apparatus disclosed in Patent Document 1, a filter circuit that can be switched according to ultrasonic probes having different operating frequencies is provided on the transmission circuit side of the ultrasonic diagnostic apparatus (the main body of the apparatus). Ultrasonic transmission is performed by blocking the harmonic components through the wave. In reception, an ultrasonic probe transducer and an inductor that forms a resonance circuit are provided, and the harmonic frequency component is cut off and the harmonic component of the harmonic is extracted.

Japanese Patent Laid-Open No. 11-188037

  In harmonic imaging by an ultrasonic diagnostic apparatus, it is necessary to transmit only the fundamental frequency during transmission and to extract only the harmonics during reception. The switching of the frequency characteristics is performed by an ultrasonic diagnostic apparatus (the main body of the apparatus) or an ultrasonic probe. However, conventionally, the switching is performed by an ultrasonic diagnostic apparatus, and is not performed by an ultrasonic probe. There wasn't. An object of the present invention is to provide a probe, an information acquisition device, and the like suitable for harmonic imaging and the like that pass a fundamental wave and cut off a harmonic component during transmission and cut off a fundamental frequency component and receive a harmonic component during reception. And

  The probe of the present invention, which is detachably connected to the body of an information acquisition device for transmitting acoustic waves to a subject and receiving reflected waves to acquire information on the subject, has the following characteristics. That is, a frequency characteristic variable filter that includes a transducer that transmits and receives acoustic waves and that is provided in an electrical signal path through which both a transmission signal and a reception signal pass, and whose frequency characteristics are switched between transmission and reception. The fundamental frequency component is cut off and the harmonic component is cut off. Upon reception, the fundamental frequency component of the received signal is cut off and the harmonic component is passed through.

  The information acquisition apparatus of the present invention for acquiring information on a subject by transmitting an acoustic wave to the subject and receiving a reflected wave has the following characteristics. That is, a probe including a transducer that transmits and receives an acoustic wave, and a frequency characteristic variable filter that is provided in an electric signal path through which both a transmission signal and a reception signal pass and whose frequency characteristic is switched between transmission and reception. The filter is characterized in that when transmitting, the fundamental frequency component of the transmission signal is passed and the harmonic component is cut off, and when receiving, the fundamental frequency component of the received signal is cut off and the harmonic component is passed.

  According to the present invention, since the frequency characteristic variable filter as described above is provided, it is possible to provide a probe and an information acquisition device suitable for harmonic imaging and the like.

(A) is a figure explaining the probe and information acquisition apparatus of Example 1, (b) is a figure explaining the frequency characteristic variable filter used for the probe of Example 1. FIG. FIG. 6 is a diagram illustrating a probe according to a second embodiment. FIG. 6 is a circuit configuration diagram of a frequency characteristic variable filter in the probe of the third embodiment. FIG. 6 is a circuit configuration diagram of a frequency characteristic variable filter in a probe according to a fourth embodiment. FIG. 10 is a circuit configuration diagram of a frequency characteristic variable filter in the probe of the fifth embodiment. (A) is a figure explaining the probe of Example 6, (b) is a circuit block diagram of the frequency characteristic variable filter in the vibrator | oscillator of Example 6. FIG. FIG. 10 is a circuit configuration diagram of a frequency characteristic variable filter in the vibrator according to the seventh embodiment. (A) is a circuit block diagram of the frequency characteristic variable filter in the probe of Example 8, (b) is a circuit block diagram of the frequency characteristic variable filter in the probe of Example 8, (c) is FIG. 10 is a circuit configuration diagram of a frequency characteristic variable filter in a probe according to an eighth embodiment. FIG. 10 is a circuit configuration diagram of a frequency characteristic variable filter in a probe according to a ninth embodiment. FIG. 25 is a circuit configuration diagram of a frequency characteristic variable filter in the probe of the tenth embodiment. FIG. 25 is a diagram for explaining the circuit operation of the probe according to the eleventh embodiment. FIG. 10 is a diagram illustrating a capacitive transducer according to a twelfth embodiment. FIG. 15 is a diagram illustrating an information acquisition apparatus according to a thirteenth embodiment.

  In the probe and information acquisition device of the present invention, a frequency characteristic variable filter that switches frequency characteristics between transmission and reception is provided in an electrical signal path through which both a transmission signal and a reception signal related to a transducer in the probe pass. It is done. When transmitting, the filter blocks the harmonic component through the fundamental frequency component of the transmission signal to the transducer, and when receiving, blocks the fundamental frequency component of the received signal from the transducer and passes the harmonic component. The probe is typically detachably connected to the main body of an information acquisition device for transmitting an acoustic wave to a subject and receiving a reflected wave to acquire information on the subject, and the frequency characteristics thereof are variable. A filter is provided. There are several methods for switching the frequency characteristics of the frequency characteristic variable filter. Performed by a switch device that is turned on / off by a control signal (logic signal) from a detection means that detects the state of a signal passing through the electrical signal path, or by a switch device that is turned on / off by the action of the signal itself passing through the electrical signal path Can do. The signal passing through the electrical signal path may be a transmission signal or a reception signal, or a signal instructing transmission or reception from a transmission / reception switch circuit that switches between transmission and reception on the main body side of the apparatus. Further, a configuration in which a frequency characteristic variable filter is provided separately from the probe is also possible. In this case, the information acquisition device includes a probe including a transducer that transmits and receives an acoustic wave, and a frequency characteristic variable filter that switches a frequency characteristic between transmission and reception in an electric signal path through which both a transmission signal and a reception signal pass. . Examples of the present invention will be described below, but the present invention is not limited to these examples, and various modifications and changes can be made within the scope of the gist.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Example 1
FIG. 1A is a diagram for explaining the probe of this embodiment. The frequency characteristic variable filter 103 is provided in the electric signal path 106 that connects the transducer head portion 102 in the probe 101 and the probe connector 104 and is a transmission / reception signal path through which both a transmission signal and a reception signal pass. Features. When transmitting a high-voltage transmission signal applied from the main body of the diagnostic apparatus, which is an information acquisition apparatus, to the transducer head unit 102 and transmitting an ultrasonic wave (at the time of transmission), the transmission signal is shown in FIG. Is transmitted from right to left. The frequency characteristic variable filter 103 gives this transmission signal a certain frequency pass characteristic A and transmits it to the transducer head unit 102. On the other hand, when receiving a signal by transmitting a small signal generated by the transducer head unit 102 receiving ultrasonic waves to the main body side of the diagnostic apparatus (during reception), the received signal is directed toward the paper surface in FIG. Is transmitted from left to right. The frequency characteristic variable filter 103 gives this received signal a certain frequency pass characteristic B and transmits it to the probe connector 104.

  The frequency characteristic variable filter of the present invention is characterized in that the frequency characteristic B given to the received signal is different from the frequency characteristic A at the time of transmission. The center frequency of the frequency pass characteristic B at the time of reception is particularly preferably about 1.5 to 3.0 times the center frequency of the frequency pass characteristic A given to the transmission signal. The optimum multiple may be selected according to how many harmonics are received in harmonic imaging.

  The present embodiment is characterized in that the frequency characteristics at the time of transmission and at the time of reception are changed by switching the circuit connection by a switch. The probe 101 and the diagnostic device 108 can be attached and detached by the probe connector 104 and the device-side connector 105, and the probes 101 having different frequencies to be used can be connected and used. The probe 101 includes a transducer head unit 102 that transmits an acoustic wave to a subject and receives a reflected wave, a probe connector 104, and a variable frequency characteristic filter 103. The transducer head unit 102 includes only a transducer or a transducer and a front end circuit. The diagnostic device 108 includes a device-side connector 105, a pulsar circuit 110 that transmits a transmission signal to the transducer, and a receiver circuit 112 that amplifies the reception signal. Further, a control / image forming unit (control image processing unit) 113 that performs transmission / reception operation control and image formation based on at least the received signal is provided. A T / R-SW (transmission / reception switch circuit) 111 is included in a general circuit configuration on the diagnostic apparatus 108 side. This is a circuit that turns off at a high voltage at the time of transmission to protect the receiver circuit 112 from a high voltage of the pulsar circuit 110 and allows a minute signal from the transducer at the time of reception to pass. The transmission / reception identification signal 107 is a logic signal that is switched in the transmission / reception time phase. The transmission / reception identification signal 107 is inverted when receiving 1 when receiving, and when transmitting 0 when inverted.

  FIG. 1B is a diagram illustrating the frequency characteristic variable filter 103 used in the probe of this embodiment. The frequency characteristic is varied by switching the filter circuit during transmission / reception. It comprises a fundamental wave filter circuit 201 that passes the fundamental wave and cuts off the harmonic component, a harmonic filter circuit 202 that cuts off the fundamental frequency component and passes the harmonic component, and a switch 203. The fundamental wave filter circuit 201 has a frequency characteristic that cuts off harmonic components through the fundamental wave of the frequency used by the probe. The harmonic filter circuit 202 has a frequency characteristic that cuts off the fundamental frequency component that matches the operating frequency of the probe and passes the harmonic component. Switching of the switch 203 is controlled by a transmission / reception identification signal 107. The signal is connected to the fundamental filter circuit 201 side or the harmonic filter circuit 202 side by the switch 203.

  At the time of transmission, the signal is connected to the fundamental wave filter circuit 201 by the switch 203. The frequency characteristic variable filter 103 can block the harmonic component through the fundamental wave by the fundamental wave filter circuit 201 during transmission. The received signal is connected to the harmonic filter circuit 202 by the switch 203 that is switched by the transmission / reception identification signal 107. Thus, at the time of reception, the harmonic filter circuit 202 can block the fundamental frequency component and pass the harmonic component. The fundamental wave filter circuit 201 is a low-pass filter or a band-pass filter whose passband frequency is the fundamental wave frequency to be used. The harmonic filter circuit 202 is a band-pass filter or a high-pass filter having a harmonic frequency as a pass band. In the diagnostic apparatus, ultrasonic waves having a frequency of about 0.1 MHz to 30 MHz are usually used. The frequency characteristics of the respective filter circuits of the present embodiment are mounted with values determined according to the operating frequency of the probe.

  The transducer head unit 102 can be used as long as it can transmit and receive ultrasonic waves, including general piezoelectric ultrasonic transducers. The frequency characteristic variable filter 103 may be mounted in the connection connector portion in the probe, the transducer head portion, or anywhere in between. The switch 203 includes a controllable switching circuit such as a relay, analog SW (switch), transistor, and FET (Field-effect-transistor field effect transistor).

  In the probe of this embodiment, the signal passes through the frequency characteristic variable filter 103 at the time of transmission / reception, so that the fundamental component is cut off at the time of transmission and the harmonic component is cut off at the time of transmission. be able to. Therefore, it is possible to adjust the transmission / reception signal optimal for harmonic imaging using only the probe, and therefore harmonic imaging can be performed without adding a special configuration to the diagnostic apparatus. In other words, since the circuit element of the frequency characteristic variable filter described above is changed for each probe having a different fundamental frequency, it is incorporated into the probe. There is no need to add circuit elements for matching. Note that probes having different fundamental frequencies can be appropriately changed to the diagnostic apparatus according to the diagnostic part and its depth. Note that harmonic imaging is a voltage signal that is received by, for example, filtering, harmonics that have been reflected by the subject and returned from the harmonics that have propagated through the medium until the transmitted ultrasound reaches the subject. Separate from. Then, the separated harmonic voltage signal is subjected to signal processing such as envelope detection, and further converted into a luminance value, and luminance information on the scanning line in the direction in which the ultrasonic wave is transmitted and received is acquired. Then, transmission / reception of ultrasonic waves is repeated for a plurality of directions and a plurality of positions in the subject, and luminance information on a plurality of scanning lines is acquired. By imaging the luminance information on the plurality of scanning lines, the inside of the subject is imaged.

(Example 2)
FIG. 2 is a diagram for explaining the probe of this embodiment. In this embodiment, the switch of the frequency characteristic variable filter is controlled by a circuit that detects a high voltage of the transmission signal in the probe.

  The probe 101 includes a transducer head section 102, a probe connector 104, a frequency characteristic variable filter 103, and a voltage detection circuit 301. The frequency characteristic variable filter has the configuration shown in FIG. The voltage detection circuit 301 outputs a logic signal as the transmission / reception identification signal 107 according to the high voltage and the low voltage depending on the voltage of the transmission / reception signal path. Since the transmission signal has a higher voltage than the reception signal, a threshold value of a logic signal for determining transmission / reception is set therebetween. The voltage of the transmission signal has a peak value of about 10V to several hundreds V, and the voltage value of the reception signal is about 0V to a maximum of about 0.5V. The voltage detection circuit 301 sets a threshold value between the minimum voltage value of the transmission voltage and the maximum voltage value of the reception signal. The transmission signal flows from the main body of the apparatus to the transducer head section, the reception signal flows from the transducer head section to the apparatus side, and the filter 103 is configured to allow signals to flow in both directions.

  In the voltage detection circuit 301, the switch 203 in the frequency variable filter 103 in FIG. 1B is connected to the fundamental filter circuit 201 when the voltage is high, and the switch 203 is connected to the harmonic filter 202 when the voltage is low. So that the logic output. As a result, at the time of transmission, it is possible to block the harmonic component through the fundamental wave, and at the time of reception, it can block the fundamental frequency component and pass the harmonic component. Here again, the switch 203 is configured by a controllable switching circuit such as a relay, an analog SW (switch), a transistor, and an FE. The probe according to the present embodiment does not require external control of the frequency characteristic variable filter switch, and can reduce the control circuit and wiring of the diagnostic apparatus.

(Example 3)
FIG. 3 is a diagram for explaining a frequency characteristic variable filter used in the probe according to the present embodiment. The circuit configuration of the frequency characteristic variable filter 103 is characterized in that the frequency of the bandpass filter is switched using a switch that is turned on during transmission.

  The inductor 401 is an inductor element, and the capacitor 402 and the capacitor 403 are capacitor elements. The switch 404 is a switch that is turned on / off by the transmission / reception identification signal 107, and performs control to turn on the switch during transmission and to turn it off during reception. When the switch 404 is turned on during transmission, assuming that the inductance value of the inductor 401 is L1, the capacitance value of the capacitor 402 is C1, and the capacitance value of the capacitor 403 is C2, the center frequency is 1 / (2πSQRT (L1 * (C1 + C2)) Since the switch 404 is turned off at the time of reception, it becomes a band pass filter with a center frequency of 1 / (2πSQRT (L1 * C2)). At the time of transmission according to the frequency used by the probe The values of L1, C1, and C2 are selected so as to be a band-pass filter that cuts off the harmonic component through the fundamental wave and a band-pass filter that cuts off the fundamental frequency component and passes the harmonic component at the time of reception. The filter 103 passes the fundamental wave during transmission and cuts off the harmonic component, and cuts off the fundamental frequency component during reception. The inductor 401 is used as a component shared during transmission and reception.

  According to the present embodiment, it is possible to simplify and share the circuit by configuring with a single-function switch that is turned on at the time of transmission and by sharing some of the components at the time of transmission and reception. Become. Whether it is a band pass filter or a low or high pass filter depends on how the inductor and the capacitor are coupled. When the inductor and the capacitor are in series on the circuit (in the case of this embodiment), it becomes a band pass, when it is only the inductor, it becomes a low pass, and when it is only the capacitor, it becomes a high pass. This can also be confirmed in the following examples.

Example 4
FIG. 4 is a diagram illustrating a frequency characteristic variable filter used in the probe according to the present embodiment. The circuit structure of the frequency characteristic variable filter 103 is characterized in that a switch that is turned on at the time of transmission is used, and a low-pass filter at the time of transmission and a band-pass filter at the time of reception are switched.

  The frequency characteristic variable filter 103 is a switch that is turned on by a transmission / reception identification signal 107 at the time of transmission, and is configured to be a low pass filter at the time of transmission and a band pass filter at the time of reception. An inductor 501 is an inductor element, a capacitor 502 and a capacitor 503 are capacitor elements, and a switch 504 and a switch 505 are switches that are turned on by transmission / reception identification signal 107 during transmission. The variable frequency filter 103 is configured as a low-pass filter of an inductor 501 and a capacitor 503 when the switch 504 and the switch 505 are turned on at the time of transmission. At the time of transmission, assuming that the inductance constant of the inductor 501 is L1 and the capacitance value of the capacitor 503 is C2, the filter operates as a low-pass filter with a cutoff frequency of 1 / (2πSQRT (L1 * C2).

  At the time of reception when both switches are turned off, it functions as a band-pass filter including the inductor 501 and the capacitor 502. Assuming that the inductance value of the inductor 501 is L1 and the capacitance value of the capacitor 503 is C1, it operates as a bandpass filter having a center frequency of 1 / (2πSQRT (L1 * C1)). In accordance with the frequency used by the probe, L1 and C1 are low-pass filters that pass the fundamental wave and cut off the harmonic components during transmission, and band-pass filters that cut off the fundamental frequency component and pass the harmonic components when receiving. , C2 is selected. Therefore, the frequency characteristic variable filter 103 passes the fundamental wave during transmission and cuts off the harmonic component, and cuts off the fundamental frequency component and passes the harmonic component during reception. The inductor 501 is used as a component shared during transmission and reception. However, the values of inductance, capacity, and resistance actually need to be determined in consideration of the transducer, cable impedance, inductance component, and capacitance component of the probe.

  According to the present embodiment, it is possible to simplify and share the circuit by configuring with a single-function switch that is turned on at the time of transmission and by sharing some of the components at the time of transmission and reception. Become.

(Example 5)
FIG. 5 is a circuit configuration diagram of the frequency characteristic variable filter of the probe of this embodiment. A switch that turns off the frequency characteristic variable filter 103 at the time of transmission is used.

  An inductor 601 and an inductor 602 are inductor elements, a capacitor 603 is a capacitor element, and a switch 604 is a switch that is turned off by a transmission / reception identification signal 107 during transmission. Two bandpass characteristics are switched by a switch 604 and used. The switch is turned off during transmission. At this time, assuming that the inductance value of the inductor 601 is L1 and the capacitance value of the capacitor 602 is C1, a band pass filter having a center frequency of 1 / (2πSQRT (L1 * C1)) is obtained during transmission. At the time of reception, the switch 604 is turned on by the transmission / reception identification signal 107. Therefore, when the inductance value of the inductor 602 is L2, the band frequency filter has a center frequency of 1 / (2πSQRT ((L1 * L2 / (L1 + L2)) * C1). .

  In accordance with the frequency used by the probe, L 1, so as to be a band pass filter that cuts off the harmonic component through the fundamental wave during transmission, and a band pass filter that cuts off the fundamental frequency component and passes the harmonic component during reception. The values of L2 and C1 are selected. Therefore, the frequency characteristic variable filter 103 passes the fundamental wave at the time of transmission and cuts off the harmonic component, and cuts off the fundamental frequency component and passes the harmonic component at the time of reception.

  It is possible to simplify and share the circuit by configuring with a single-function switch that is turned off at the time of transmission and by sharing a part of the components at the time of transmission and reception.

(Example 6)
FIG. 6A is a configuration diagram of the probe of this embodiment. As shown in FIG. 6B, a device that functions as a switch that turns on when the voltage is high and a device that functions as a switch that turns off when the voltage is high are used in the frequency characteristic variable filter.

  FIG. 6B is a circuit configuration diagram of the frequency characteristic variable filter of the probe of the present embodiment. It is an example of the structure of the frequency characteristic variable filter which changes a frequency characteristic with the device which works as a switch which turns on or turns off when the voltage is high. The high voltage on device 801 is a device that is turned on by a high voltage, and the high voltage off device 802 is a device that is turned off by a high voltage. At the time of transmission, since the transmission signal becomes a high voltage, the high voltage on device 801 is turned on and the high voltage off device is turned off. At this time, the fundamental wave filter circuit 201 is inserted. At the time of reception, since the received signal from the transducer head has a low voltage, the high voltage on device 801 is turned off, the high voltage off device 802 is turned on, and the harmonic filter circuit 202 is inserted. At the time of transmission, the transmission signal passes through the fundamental wave filter circuit 201, thereby passing the fundamental wave and blocking the harmonic component. At the time of reception, the received signal passes through the harmonic filter circuit 202 to block the fundamental frequency component and pass the harmonic component.

  With this configuration, transmission / reception switching control from the apparatus side is not required, a voltage detection circuit is not required in the probe, and transmission / reception switching control signals are not required. As a device that is turned on when the voltage is high, a switching diode or a combination of a voltage detector, a transistor, and an FET can be used. As a device that is turned off when the voltage is high, a T / R switch IC used in a transmission / reception circuit of the diagnostic apparatus, an IC protector, a device that is an IC formed by a combination of a voltage detection unit, a transistor, and an FET can be used.

  According to the present embodiment, it is possible to simplify and share the circuit by configuring with a single-function switch that is turned on at the time of transmission and by sharing some of the components at the time of transmission and reception. Become.

(Example 7)
FIG. 7 is a circuit configuration diagram of a frequency characteristic variable filter used in the probe of this embodiment. It is a device that functions as a switch that is turned on by a high voltage, and is configured to switch the frequency characteristics of the bandpass filter.

  The inductor 901 is an inductor element, the capacitor 902, and the capacitor 903 are capacitor elements. The high voltage on device 904 is a device that is turned on by a high voltage. At the time of transmission, the switch 904 is turned on with a high voltage of the transmission signal. Assuming that the inductance value of the inductor 901 is L1, the capacitance value of the capacitor 902 is C1, and the capacitance value of the capacitor 903 is C2, a band-pass filter having a center frequency of 1 / (2πSQRT (L1 * (C1 + C2)) is obtained. Since the switch 904 is turned off, it becomes a band-pass filter having a center frequency of 1 / (2πSQRT (L1 * C2)), and in accordance with the frequency used by the probe, transmits the fundamental wave and cuts off the harmonic component. The values of L1, C1, and C2 are selected so that the band-pass filter is a band-pass filter that cuts off the fundamental frequency component during reception and passes the harmonic component. Cuts off the harmonic components and cuts off the fundamental frequency components and passes the harmonic components during reception.

  According to the present embodiment, the inductor 901 is used as a component shared during transmission and reception. By configuring with a single-function switch that is turned on at the time of transmission, and by sharing some of the components at the time of transmission and reception, it becomes possible to simplify and share the circuit.

(Example 8)
FIG. 8A is a circuit configuration diagram of a frequency characteristic variable filter used in the probe of this embodiment. A device that functions as a switch that is turned on by a high voltage, and is configured to switch to a low-pass filter during transmission and to switch to a band-pass filter during reception.

  The inductor 1001 is an inductor element, the capacitor 1002, the capacitor 1003 is a capacitor element, and the high voltage on devices 1004 and 1005 are devices that are turned on by a high voltage. In a state where the switch 1004 and the switch 1005 are turned on by a high voltage at the time of transmission, a low-pass filter including an inductor 1001 and a capacitor 1003 is configured. When transmitting, assuming that the inductance constant of the inductor 1001 is L1 and the capacitance value of the capacitor 1003 is C2, it operates as a low-pass filter with a cutoff frequency of 1 / (2πSQRT (L1 * C2). At the time of reception when the switch is turned off, the inductor 1001 And a capacitor 1002. When the inductance value of the inductor 501 is L1 and the capacitance value of the capacitor 1003 is C1, the filter operates as a bandpass filter having a center frequency of 1 / (2πSQRT (L1 * C1)).

  In accordance with the frequency used by the probe, L1 and C1 are low-pass filters that pass the fundamental wave and cut off the harmonic components during transmission, and band-pass filters that cut off the fundamental frequency component and pass the harmonic components when receiving. , C2 is selected. Therefore, the frequency characteristic variable filter 103 passes the fundamental wave at the time of transmission and cuts off the harmonic component, and cuts off the fundamental frequency component and passes the harmonic component at the time of reception. The inductor 1001 is used as a component shared during transmission and reception. The values of inductance, capacitance, and resistance need to be determined in consideration of the transducer, cable impedance, inductance component, and capacitance component of the probe.

  It is possible to simplify and share the circuit by configuring with a single-function switch device that is turned on at a high voltage and by sharing some of the components during transmission and reception.

  FIG. 8B shows an embodiment in which a switch that is turned on when the voltage in FIG. This utilizes the switching characteristics depending on the voltage of the diode. The voltage threshold value of the diode switching operation is usually about 0.5 to 1V. Instead of the switches 1004 and 1005 in FIG. 8A, diodes 1104 and 1105 and diodes 1106 and 1107 that are arranged in parallel in opposite directions are connected. By using a two-piece diode package, it can be handled as one device. Since a diode is turned on as a switch when a high voltage is applied during transmission, the diode operates as a low-pass filter with a cutoff frequency of 1 / (1πSQRT (L1 * C2) during transmission. It operates as a bandpass filter of (2πSQRT (L1 * C1)).

  In order to prevent waveform ringing and overshoot during transmission, a configuration may be adopted in which a damping resistor is inserted. FIG. 8C is a circuit example in which a resistor that performs a damping operation at the time of transmission is added. A damping resistor 1201 is added.

Example 9
FIG. 9 is a circuit configuration diagram of a frequency characteristic variable filter used in the probe of this embodiment. A device that functions as a switch that turns off when the voltage is high is used as the frequency characteristic variable filter 103, and the frequency characteristic of the bandpass filter is switched.

  The inductors 1301 and 1302 are inductor elements, the capacitor 1303 is a capacitor element, and the high voltage off switch 1304 is a device that is turned off by a high voltage. Since a high voltage is applied during transmission, the high voltage off switch 1304 is turned off. At this time, assuming that the inductance value of the inductor 1301 is L1 and the capacitance value of the capacitor 1302 is C1, a band-pass filter having a center frequency of 1 / (2πSQRT (L1 * C1)) is obtained during transmission. Since the high voltage off switch 1304 is turned on because the voltage is low during reception, the center frequency is 1 / (2πSQRT ((L1 * L2 / (L1 + L2)) * C1) when the inductance value of the inductor 1302 is L2. It becomes a path filter.

  In accordance with the frequency used by the probe, L1 is a bandpass filter that cuts off the harmonic component through the fundamental wave during transmission, and a bandpass filter that cuts off the fundamental frequency component and passes the harmonic component during reception. , L2 and C1 are selected. Therefore, the frequency characteristic variable filter 103 functions to pass the fundamental wave through and cut off the harmonic component at the time of transmission, and cut off the fundamental frequency component and pass the harmonic component at the time of reception.

  It is possible to simplify and share the circuit by configuring with a single-function device that turns off when the voltage is high, or by sharing some of the components during transmission and reception.

(Example 10)
FIG. 10 is a diagram for explaining the probe of this embodiment. The frequency characteristic variable filter can be switched between valid and invalid by a switch. The filter on / off switch 1401 is a mechanical switch that is connected in parallel to the frequency characteristic variable filter 103 and can be manually turned on / off. By using the filter on / off switch 1401 on and off, the frequency characteristic variable filter 103 can be used effectively and disabled. When the filter on / off switch 1201 is off, the frequency characteristic variable filter 103 is valid, and when it is on, it is invalid. There is an advantage that can be dealt with when harmonic imaging is not used. A switch for external control may be used. Depending on the circuit configuration and switch configuration, the frequency characteristic variable filter 103 may function only during transmission or only during reception. Alternatively, the switch 1401 may be turned on / off by a signal from the voltage detection circuit 301, or may be turned on / off by a switching signal from the main body of the apparatus.

(Example 11)
FIG. 11 is a diagram for explaining the operation of the probe of this embodiment. A variable frequency filter is combined with a reception front end circuit. A reception front-end circuit that amplifies or impedance-converts a received signal in the transducer head portion 102 of the probe and a transmission / reception frequency switching filter 103 are combined.

  FIG. 11A is a block diagram in the case where a reception front-end circuit is configured in the transducer head unit 102. The transducer 1501 is an acoustic wave and electric signal transducer. The reception front-end circuit 1502 is a circuit that amplifies or impedance-converts the reception signal of the transducer. The transmission path switch 1503 is a switch that is turned on at the time of transmission. At the time of transmission, the transmission path switch 1503 is on, and a transmission signal is sent to the transducer without passing through the reception front-end circuit 1502. At the time of reception, the transmission path switch 1503 is off, and a reception signal is sent to the apparatus side via the reception front end circuit 1502. The reception front end circuit 1502 allows the reception signal from the transducer head unit 102 to be sent to the diagnostic apparatus side with a lower output impedance than when it is output from the transducer alone.

  FIG. 11B shows a configuration of a comparative example using only a transducer. FIG. 11C shows the connection between the frequency switching filter for transmission / reception and the diagnostic device by modeling the transducer head portion as a signal source 1504 and an output impedance 1505. The signal source 1504 is a signal generation source whose frequency is variable with a sine wave of a minute voltage, and the output impedance 1505 is the output impedance of the signal source. The impedance 1508 is the impedance of the device side circuit. An inductor 1506 is an inductor element, and a capacitor 1507 is a capacitor element, which is a band-pass filter of a transmission / reception frequency filter configured at the time of reception. When this model is considered, the output impedance 1505 is large when the transducer head unit is a single transducer, and the output impedance 1505 is small when there is a reception front-end circuit.

  FIG. 11D shows the frequency characteristics of the diagnostic device calculated based on the level of the signal source 1504. A small output impedance graph 1509 is a frequency characteristic curve when the output impedance is small, and a large output impedance graph 1510 is a frequency characteristic curve when the output impedance is large. When the output impedance is large, the frequency characteristic becomes flat as shown in the graph of large output impedance 1510, and when the output impedance is low, the characteristic becomes steep as shown by the graph curve frequency 1509. This means that using a front-end circuit and reducing the output impedance makes it easier to obtain frequency characteristics for extracting only harmonics. For this reason, a combination of the transducer head unit and the reception signal front-end circuit facilitates extraction of harmonics during reception.

(Example 12)
In this embodiment, the CMUT is used for the transducer head unit 102, which is different from the other embodiments. CMUT (Capacitive-Micromachined-Ultrasonic-Transducers) is a capacitive transducer. This is produced by a MEMS (Micro-Electro-Mechanical-Systems) technology using a semiconductor process.

  FIG. 12 is a diagram for explaining the vibrator (CMUT) of the present embodiment. The CMUT has a first electrode 13 fixed on the substrate and a second electrode 12 disposed to face the first electrode. The second electrode 12 is disposed on the vibration film 11 and has a structure that vibrates integrally with the vibration film 11. The vibration film 11 is held on the substrate 10 by the support portion 14.

  A DC voltage generating means 21 is connected to the second electrode 12. A predetermined DC voltage Va is applied to the second electrode 12 from the DC voltage generating means 21. The other first electrode 13 is connected to the transmission / reception circuit 22 and has a fixed potential in the vicinity of the GND potential. Thereby, a potential difference of Vbias = Va−0V is generated between the first electrode 13 and the second electrode 12. Thus, reception can be performed with high reception efficiency.

  In addition, by applying an alternating drive voltage to the first electrode 13 by the transmission / reception circuit 22, an alternating electrostatic attractive force is generated between the first and second electrodes, and the vibrating membrane 11 is caused to have a certain frequency. An ultrasonic wave can be transmitted by vibrating. On the other hand, when the vibration film 11 receives an ultrasonic wave and vibrates, a minute current is generated in the first electrode 13 by electrostatic induction, and the current value is measured by the transmission / reception circuit 22 to extract a received signal. Can do. An input / output terminal 30 connected to the outside of the transmission / reception circuit 22 is a connection terminal to the electric signal path 106 of the transducer head unit 102, and is connected to the electric signal path 106.

  Since the CMUT uses a vibrating membrane having electrodes, the frequency response at the time of transmission / reception is superior to a transducer using a piezoelectric element having electrical resonance characteristics. Therefore, it is suitable for harmonic imaging using frequency regions that are greatly different between transmission and reception. However, since it responds to the frequency component of the transmission signal, it also responds to the harmonic component of the transmission signal, and the harmonic component tends to be superimposed on the transmitted ultrasonic wave. When a CMUT is used for the transducer head unit 102, the configuration of the present invention having a variable filter with different frequency characteristics for transmission and reception can be used even when a signal including harmonics is applied to the transmission signal. Ultrasound with suppressed components can be transmitted from the CMUT. Further, since CMUT receives a signal in a wide frequency range even at the time of reception, it detects a received signal other than the desired frequency region, which hinders highly sensitive detection. Since the necessary frequency region can be limited by using the configuration of the present embodiment, only the harmonic component can be detected with high sensitivity.

  Therefore, according to the present embodiment, it is possible to perform transmission of the fundamental wave and reception of the harmonic by making use of the characteristics of the CMUT having a wide frequency band, which is superior to the case where a piezo is used as the transducer. Harmonic imaging signals can be acquired. Therefore, by connecting the probe of this embodiment to the diagnostic apparatus and using it, higher-quality harmonic imaging can be performed without changing the main body of the apparatus.

  In the above description, the DC voltage generating means 21 is connected to the second electrode 12, and the first electrode 13 is connected to the transmission / reception circuit 22. However, the transmission / reception circuit 22 is connected to the second electrode 12, and the first electrode is connected to the first electrode 13. A configuration in which 13 is connected to the DC voltage generating means 21 can be used similarly. In this embodiment, the transducer head unit 102 has been described using a CMUT. However, a transducer such as PVDF (polyvinylidene fluoride) having excellent frequency characteristics as compared with piezo can also be used.

(Example 13)
The transducer described in the above embodiment can be applied to a subject information acquisition apparatus using acoustic waves. The transducer receives the acoustic wave from the subject and uses the output electrical signal to obtain subject information that reflects the subject's optical characteristic values such as the optical absorption coefficient and the subject information that reflects the difference in acoustic impedance. can do.

  FIG. 13A shows an object information acquisition apparatus using the photoacoustic effect. Pulse light generated from the light source 40 is irradiated to the subject 44 through an optical member 42 such as a lens, a mirror, or an optical fiber. The light absorber 46 inside the subject 2014 absorbs the energy of the pulsed light and generates a photoacoustic wave 48 that is an acoustic wave. The transducer 50 in the probe (ie, the probe) 52 receives the photoacoustic wave 48, converts it into an electrical signal, and outputs it to the signal processing unit 54. The signal processing unit 54 performs signal processing such as A / D conversion and amplification on the input electrical signal and outputs the signal to the data processing unit 56. The data processing unit 56 acquires object information (characteristic information reflecting the optical characteristic value of the object such as a light absorption coefficient) as image data using the input signal. Here, the signal processing unit 54 and the data processing unit 56 are referred to as a processing unit, and this substantially corresponds to the control image processing unit 113 in FIG. The display unit 58 displays an image based on the image data input from the data processing unit 56.

  FIG. 13B shows a subject information acquiring apparatus such as an ultrasonic echo diagnostic apparatus using reflection of acoustic waves. The acoustic wave transmitted from the transducer 70 in the probe (ie, probe) 72 to the subject 64 is reflected by the reflector 66. The transducer 70 receives the reflected acoustic wave 68 (reflected wave), converts it into an electrical signal, and outputs it to the signal processing unit 74. The signal processing unit 74 performs signal processing such as A / D conversion and amplification on the input electric signal and outputs the signal to the data processing unit 76. The data processing unit 76 (acquisition unit) acquires object information (characteristic information reflecting a difference in acoustic impedance) as image data using the input signal. Here, the signal processing unit 74 and the data processing unit 76 are also referred to as a processing unit. The display unit 78 displays an image based on the image data input from the data processing unit 76.

  The probe may be one that scans mechanically or one that a user such as a doctor or engineer moves with respect to the subject (hand-held type). In the case of a device that uses reflected waves as shown in FIG. 13B, the probe that transmits the acoustic wave may be provided separately from the probe that receives the acoustic wave.

  Furthermore, the apparatus has both the functions of the apparatus of FIG. 13A and FIG. 13B, and the object information reflecting the optical characteristic value of the object and the object information reflecting the difference in acoustic impedance, Both of them may be acquired. In this case, the transducer 50 in FIG. 13A may transmit not only the photoacoustic wave but also the acoustic wave and the reflected wave. Specifically, when the photoacoustic effect is used, the transducer in the probe (that is, the probe) receives a photoacoustic wave generated in the subject. In this case, the transducer blocks the harmonic component of the received photoacoustic wave and allows the fundamental frequency component to pass through the variable frequency characteristic filter. On the other hand, in the case of ultrasonic echo diagnosis, a transducer in a probe (that is, a probe) transmits an acoustic wave to a subject and receives an acoustic wave reflected in the subject. In this case, the transducer in the probe (that is, the probe) passes the fundamental wave through the fundamental wave at the time of transmission and cuts off the harmonic component at the time of reception by the frequency characteristic variable filter described above. An example of such usage is as an example.

  The apparatus according to the present invention can be used mainly for an ultrasonic diagnostic apparatus, but can also be used for an information acquisition apparatus that uses frequency characteristic switching.

  101 ··· Probe, 102 · · Transducer head (transducer), 103 · · Frequency characteristic variable filter, 106 · · Electrical signal path, 108 · · Body

Claims (24)

A probe that is detachably connected to the body of an information acquisition device for transmitting an acoustic wave to a subject and receiving a reflected wave to acquire information on the subject,
It has a transducer that transmits and receives acoustic waves,
In the electrical signal path through which both the transmission signal and the reception signal pass, a frequency characteristic variable filter that switches the frequency characteristic between transmission and reception is provided,
The variable frequency characteristic filter is characterized in that during transmission, the fundamental frequency component of the transmission signal is cut off and the harmonic component is cut off, and during reception, the fundamental frequency component of the received signal is cut off and the harmonic component is passed through. Tentacles.   2. The probe according to claim 1, wherein the switching of the frequency characteristic variable filter is performed using a signal passing through the electric signal path.   The probe according to claim 2, wherein the switching of the frequency characteristic variable filter is performed by a switch that is turned on / off by a signal from a voltage detection unit that detects a voltage of a signal passing through the electric signal path.   4. The search according to claim 3, wherein the switching of the frequency characteristic variable filter is performed by a switch that is turned on / off by a signal based on the fact that the voltage detection means detects that the transmission signal is higher in voltage than the reception signal. Tentacles.   3. The probe according to claim 2, wherein the switching of the frequency characteristic variable filter is performed by a switch that is turned on / off by the action of a signal passing through the electrical signal path.   The switching of the frequency characteristic variable filter is performed by a switch on / off by a signal instructing transmission or reception from a transmission / reception switch circuit for switching between transmission and reception on the main body side. 2. The probe according to 2.   The probe according to any one of claims 1 to 6, wherein the frequency characteristic variable filter switches a band-pass filter between transmission and reception by a switch that is turned on during transmission.   7. The frequency characteristic variable filter according to claim 1, wherein the filter is switched between a low pass filter at the time of transmission and a band pass filter at the time of reception by a switch that is turned on at the time of transmission. 8. Transducer.   The probe according to any one of claims 1 to 6, wherein the frequency characteristic variable filter switches a band-pass filter between transmission and reception by a switch that is turned off during transmission.   6. The probe according to claim 5, wherein the switching of the frequency characteristic variable filter is performed by a switch device including a switch that is turned on and a switch that is turned off by a transmission signal passing through the electrical signal path.   6. The probe according to claim 5, wherein the frequency characteristic variable filter switches a band-pass filter between transmission and reception by a switch that is turned on by the transmission signal.   6. The probe according to claim 5, wherein the frequency characteristic variable filter switches a filter between a low pass filter at the time of transmission and a band pass filter at the time of reception by a switch that is turned on by the transmission signal. 6. The probe according to claim 5, wherein the frequency characteristic variable filter switches a band-pass filter between transmission and reception by a switch that is turned off by the transmission signal.   The probe according to any one of claims 1 to 13, further comprising a switch that switches between enabling and disabling the frequency characteristic variable filter.   The probe according to any one of claims 1 to 14, wherein a reception front-end circuit for amplifying or impedance-converting a reception signal and the frequency characteristic variable filter are combined.   The probe according to claim 1, wherein the transducer is a capacitive transducer.   The frequency characteristic variable filter is configured such that the center frequency of the frequency pass characteristic at the time of reception is 1.5 to 3.0 times the center frequency of the frequency pass characteristic that the transmission signal has. The probe according to any one of claims 1 to 16. An information acquisition device for acquiring information on a subject by transmitting an acoustic wave to the subject and receiving a reflected wave,
A probe including a transducer that transmits and receives an acoustic wave, and a frequency characteristic variable filter that switches a frequency characteristic between a transmission time and a reception time in an electric signal path through which a transmission signal and a reception signal pass,
The frequency characteristic variable filter is configured to block a harmonic component through a fundamental frequency component of a transmission signal at the time of transmission, and block a fundamental frequency component of a reception signal and pass a harmonic component at the time of reception. Acquisition device.   20. The information acquisition apparatus according to claim 18, further comprising an image forming unit that forms an image of a subject using at least a reception signal from the transducer. The information acquisition apparatus according to claim 18, wherein the image forming unit forms an image of a subject by harmonic imaging. A probe that receives acoustic waves from the subject and converts them into electrical signals;
An acquisition unit that acquires information on the subject using the electrical signal,
The information acquisition device according to claim 1, wherein the probe is the probe according to claim 1.   The information acquisition apparatus according to claim 21, wherein the probe transmits an acoustic wave from the probe to the subject and receives an acoustic wave reflected from the subject.   The information acquisition apparatus according to claim 21, wherein the probe receives an acoustic wave generated by irradiating the subject with light.   The information acquisition apparatus according to claim 23, further comprising a light source that irradiates the subject with light.

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