JP6024155B2 - Ultrasonic device, ultrasonic probe, electronic device and diagnostic device - Google Patents

Description

The present invention is an ultrasonic device, an ultrasonic probe, an electronic apparatus and diagnostic equipment and the like.

  2. Description of the Related Art As an apparatus for irradiating ultrasonic waves toward an object and receiving reflected waves from interfaces with different acoustic impedances inside the object, for example, an ultrasonic diagnostic apparatus for inspecting the inside of a human body is known . As an ultrasonic device (ultrasonic probe) used in an ultrasonic diagnostic apparatus, in Patent Document 1, piezoelectric elements are arranged in a matrix array, and a wire is provided for each row and column so that beams are emitted in the row direction and the column direction. A technique for scanning is disclosed. However, this method has a problem that the ultrasonic wave intensity is reduced by changing the potential of the common electrode line when the light is emitted to the front of the array.

JP 2006-61252 A

  According to some aspects of the present invention, it is possible to provide an ultrasonic device, an ultrasonic probe, an electronic device, a diagnostic device, a processing device, and the like that can reduce changes in ultrasonic intensity during phase scanning.

  One aspect of the present invention includes an ultrasonic element array and a variable capacitance circuit, and the ultrasonic element array includes a plurality of ultrasonic elements arranged in a first direction in each ultrasonic element row. 1 ultrasonic element array to nth (n is an integer greater than or equal to 2) ultrasonic element array, a first signal line to an nth signal line wired along the first direction, and the first A first common electrode line to an m-th (m is an integer of 2 or more) common electrode line wired along a second direction intersecting with the first direction, and the first ultrasonic element array The n-th ultrasonic element array is arranged along the second direction, and the j-th (j is 1 ≦ 1) among the first ultrasonic element array to the n-th ultrasonic element array. The first electrodes included in each of the plurality of ultrasonic elements constituting an ultrasonic element array of j ≦ n are the first signal line to the nth. The second electrodes connected to the j-th signal line among the signal lines and included in each of the plurality of ultrasonic elements constituting the j-th ultrasonic element array are the first common electrode line to the first electrode line. the variable capacitance circuit is connected in common to the first common electrode line to the m-th common electrode line, and the capacitance value of the variable capacitance circuit is The present invention relates to an ultrasonic device that is set to a capacitance value corresponding to the operating state of the ultrasonic device.

  According to one aspect of the present invention, capacitance can be added to the first to m-th common electrode lines, and the capacitance value can be changed according to the operating state. Fluctuations in the potential can be reduced. As a result, a decrease in the intensity of the emitted ultrasonic wave can be suppressed, so that the ultrasonic intensity can be made constant regardless of the operating state.

  In the aspect of the invention, each of the ultrasonic element arrays of the first to nth ultrasonic element arrays may be the plurality of ultrasonic elements along the first direction. The first ultrasonic element to the m-th ultrasonic element are arranged, and i (i is 1 ≦ i ≦ m) of the first to m-th ultrasonic elements. The second electrode included in the (integer) ultrasonic element may be connected to an i-th common electrode line among the first common electrode line to the m-th common electrode line.

  In this way, for example, the ultrasonic elements can be arranged in a matrix of m rows and n columns, and the second electrode of each ultrasonic element in the i-th row can be connected to the i-th common electrode line.

  In one embodiment of the present invention, the first drive signal to the n-th drive signal having the same phase are input to the first signal line to the n-th signal line during phase scanning of ultrasonic output. In the first operating state, the capacitance value of the variable capacitance circuit is set to the first capacitance value, and the first signal line to the nth signal line have phases different from each other with respect to the first signal line to the nth signal line. In the second operation state in which the drive signal to the n-th drive signal are input, the capacitance value of the variable capacitance circuit may be set to a second capacitance value smaller than the first capacitance value.

  In this way, a large capacitance value is set in the first operation state in which drive signals having the same phase are input, and a small capacitance value is set in the second operation state in which drive signals having different phases are input. The By doing so, it is possible to suppress a decrease in the intensity of the emitted ultrasonic wave in the first state in which the voltage fluctuation of the common electrode line becomes large.

  In one embodiment of the present invention, the first drive signal to the nth drive signal are input to the first signal line to the nth signal line in the first period to the nth period. The second capacitance value of the variable capacitance circuit may be set according to the degree of overlap between the first period and the nth period.

  In this way, since the capacitance value is set according to the degree of overlap between the first to nth periods, it is possible to suppress changes in ultrasonic intensity due to the beam direction during phase scanning.

  In the aspect of the invention, the second capacitance value of the variable capacitance circuit may be set to a larger value as the degree of overlap between the first period to the nth period is larger.

  In this way, the capacitance value can be set to a large value when the degree of overlap between the first to n-th periods is large, that is, when the voltage fluctuation of the common electrode line becomes large. It is possible to reduce the change in the ultrasonic intensity depending on the direction.

  In one embodiment of the present invention, the variable capacitance circuit is electrically connected to the first common electrode line to the m-th common electrode line during a transmission period in which ultrasonic waves are emitted, and an ultrasonic echo signal May be electrically disconnected from the first common electrode line to the m-th common electrode line.

  In this way, since the capacitance of the variable capacitance circuit can be electrically disconnected from the common electrode line during the reception period, it is possible to prevent a reduction in reception sensitivity when receiving an echo signal.

  In one embodiment of the present invention, the variable capacitance circuit may include a capacitive element including a piezoelectric element.

  In this way, the capacitive element can be formed by the same manufacturing process as the ultrasonic element, and thus can be formed on the same substrate as the ultrasonic element array.

  Another aspect of the present invention relates to an ultrasonic probe including any of the ultrasonic devices described above.

  Another aspect of the present invention relates to an electronic apparatus including the ultrasonic device according to any one of the above.

  In another aspect of the present invention, a control unit may be included that sets the capacitance value of the variable capacitance circuit to a capacitance value corresponding to the operating state of the ultrasonic apparatus.

  In this way, the control unit can set the capacitance value of the variable capacitance circuit to a capacitance value according to the operating state of the ultrasonic device, thereby reducing the change in ultrasonic intensity due to the beam direction during phase scanning. It becomes possible to do.

  Another aspect of the present invention relates to a diagnostic apparatus including any of the ultrasonic apparatuses described above.

  Another aspect of the present invention is a processing apparatus of an ultrasonic device having an ultrasonic element array, wherein a transmission / reception unit that performs transmission / reception processing of the ultrasonic element array, a variable capacitance circuit, control of the transmission / reception unit, and the A control unit that performs control to set a capacitance value of the variable capacitance circuit, and the ultrasonic element array includes a first element in which a plurality of ultrasonic elements are arranged along a first direction in each ultrasonic element row. Ultrasonic element array to nth (n is an integer of 2 or more) ultrasonic element array, first signal line to nth signal line wired along the first direction, and the first A first common electrode line to m-th (m is an integer of 2 or more) common electrode lines wired along a second direction intersecting the direction, the first ultrasonic element array to the The n-th ultrasonic element row is arranged along the second direction, and the first ultrasonic element row to the front Among the n-th ultrasonic element arrays, the first electrodes of the plurality of ultrasonic elements constituting the j-th ultrasonic element array (j is an integer satisfying 1 ≦ j ≦ n) are The second electrodes connected to the jth signal line among the first signal line to the nth signal line and included in each of the plurality of ultrasonic elements constituting the jth ultrasonic element row, Connected to any one of the first common electrode line to the m-th common electrode line, and the variable capacitance circuit is commonly connected to the first common electrode line to the m-th common electrode line, The control unit relates to a processing device that sets a capacitance value of the variable capacitance circuit to a capacitance value corresponding to an operation state of the ultrasonic device.

  According to another aspect of the present invention, the capacitance value of the variable capacitance circuit connected to the common electrode line of the ultrasonic element array can be set to a capacitance value according to the operating state of the ultrasonic device. It is possible to reduce the change in ultrasonic intensity due to the beam direction during scanning.

1A and 1B are basic configuration examples of an ultrasonic element. 1 is a configuration example of an ultrasonic device. The figure explaining the phase scan in an ultrasonic device. 4A, 4B, and 4C are diagrams illustrating changes in the potential of the common electrode line during phase scanning. 5A and 5B show examples of drive signal waveforms and common electrode line voltage fluctuations. 6A and 6B show examples of drive signal waveforms and voltage fluctuations of the common electrode lines. FIG. 7A illustrates stabilization of the potential of the common electrode line. FIG. 7B illustrates a first configuration example of the variable capacitance circuit. FIG. 7C illustrates a second configuration example of the variable capacitance circuit. 8A and 8B show examples of drive signal waveforms and common electrode line voltage fluctuations when a variable capacitance circuit is provided. 9A and 9B show examples of drive signal waveforms and common electrode line voltage fluctuations when a variable capacitance circuit is provided. An example of the capacity | capacitance setting by the 2nd structural example of a variable capacity circuit. A basic configuration example of a probe head, an ultrasonic probe, and an electronic device.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are indispensable as means for solving the present invention. Not necessarily.

1. Ultrasonic Element FIGS. 1A and 1B show a basic configuration example of an ultrasonic element UE included in the ultrasonic apparatus of the present embodiment. The ultrasonic element UE of the present embodiment includes a first electrode layer EL1, a piezoelectric layer PE, a second electrode layer EL2, a membrane (support member) MB, and a cavity region (cavity part) CAV. Note that the ultrasonic element UE of the present embodiment is not limited to the configuration of FIG. 1, and various components such as omitting some of the components, replacing them with other components, and adding other components. Variations are possible.

  FIG. 1A is a plan view of an ultrasonic element UE formed on a substrate (silicon substrate) SUB, as viewed from a direction perpendicular to the substrate on the element formation surface side. FIG. 1B is a cross-sectional view showing a cross section along A-A ′ of FIG.

  The first electrode layer EL1 is formed of, for example, a metal thin film on the membrane MB. As shown in FIG. 1A, the first electrode layer EL1 may be a wiring that extends to the outside of the element formation region and is connected to the adjacent ultrasonic element UE.

The piezoelectric layer PE is formed of, for example, a PZT (lead zirconate titanate) thin film, and is provided so as to cover at least a part of the first electrode layer EL1. The material of the piezoelectric layer PE is not limited to PZT. For example, lead titanate (PbTiO ₃ ), lead zirconate (PbZrO ₃ ), lead lanthanum titanate ((Pb, La) TiO ₃ ), etc. May be used.

  The second electrode layer EL2 is formed of a metal thin film, for example, and is provided so as to cover at least a part of the piezoelectric layer PE. As shown in FIG. 1A, the second electrode layer EL2 may be a wiring that extends outside the element formation region and is connected to the adjacent ultrasonic element UE.

The membrane MB is provided in the upper layer of the cavity region CAV by a two-layer structure of, for example, a SiO ₂ thin film and a ZrO ₂ thin film. The membrane MB supports the piezoelectric layer PE and the first and second electrode layers EL1 and EL2, and can vibrate according to the expansion and contraction of the piezoelectric layer PE to generate ultrasonic waves.

  The cavity region CAV is formed by etching by reactive ion etching (RIE) or the like from the back surface (surface on which no element is formed) side of the silicon substrate SUB. Ultrasonic waves are radiated from the opening OP of the cavity region CAV.

  The first electrode of the ultrasonic element UE is formed by the first electrode layer EL1, and the second electrode is formed by the second electrode layer EL2. Specifically, the portion of the first electrode layer EL1 covered by the piezoelectric layer PE forms the first electrode, and the portion of the second electrode layer EL2 that covers the piezoelectric layer PE is the second electrode. An electrode is formed. That is, the piezoelectric layer PE is provided between the first electrode and the second electrode.

  The piezoelectric layer PE expands and contracts in the in-plane direction when a voltage is applied between the first electrode and the second electrode, that is, between the first electrode layer EL1 and the second electrode layer EL2. One surface of the piezoelectric layer PE is bonded to the membrane MB via the first electrode layer EL1, but the second electrode layer EL2 is formed on the other surface, but on the second electrode layer EL2, No other layer is formed. Therefore, the membrane MB side of the piezoelectric layer PE is difficult to expand and contract, and the second electrode layer EL2 side is easily expanded and contracted. Therefore, when a voltage is applied to the piezoelectric layer PE, the convex bending occurs on the cavity region CAV side, and the membrane MB is bent. By applying an alternating voltage to the piezoelectric layer PE, the membrane MB vibrates in the film thickness direction, and ultrasonic waves are radiated from the opening OP by the vibration of the membrane MB. The voltage applied to the piezoelectric layer PE is, for example, 10 to 30 V, and the frequency is, for example, 1 to 10 MHz.

2. Ultrasonic Device FIG. 2 shows a configuration example of the ultrasonic device 200 of the present embodiment. The ultrasonic device 200 of this configuration example includes an ultrasonic element array 100 and a variable capacitance circuit 110. The ultrasonic element array 100 includes first to nth (n is an integer of 2 or more) ultrasonic element arrays UEC1 to UECn, and 1st to nth (n is an integer of 2 or more) signal lines. DL1 to DLn and first to m-th (m is an integer of 2 or more) common electrode lines CL1 to CLm are included. FIG. 2 shows a case where m = 8 and n = 12, as an example, but other values may be used. Note that the ultrasonic apparatus 200 of the present embodiment is not limited to the configuration in FIG. 2, and various components such as omitting some of the components, replacing them with other components, and adding other components. Variations are possible.

  The first to nth ultrasonic element arrays UEC1 to UECn each have a plurality of ultrasonic elements UE arranged along the first direction D1. Specifically, each ultrasonic element row UEC includes a first ultrasonic element to an m-th ultrasonic element in which a plurality of ultrasonic elements are arranged along the first direction D1. The first to nth ultrasonic element rows UEC1 to UECn are arranged along a second direction D2 that intersects the first direction D1. For example, in FIG. 2, the first to twelfth ultrasonic element rows UEC1 to UEC12 are arranged along the second direction D2.

  The ultrasonic element UE can be configured as shown in FIGS. 1A and 2B, for example. In the following description, when the position of the ultrasonic element UE in the array is specified, for example, the ultrasonic element located in the fourth row and the sixth column is denoted as UE46. For example, the sixth ultrasonic element array UEC6 includes eight ultrasonic elements UE16, UE26,... UE76, UE86.

  The first to eighth (mth in a broad sense) common electrode lines CL1 to CL8 are wired along the second direction D2 in the ultrasonic element array 100. The second electrodes respectively included in the plurality of ultrasonic elements constituting the jth ultrasonic element array UECj are connected to any one of the first to mth common electrode lines CL1 to CLm. Specifically, for example, as shown in FIG. 2, the i-th common electrode line CLi (i is an integer satisfying 1 ≦ i ≦ 8) among the first to eighth common electrode lines CL1 to CL8 is The i-th ultrasonic element UE of the ultrasonic element row UEC is connected to the second electrode.

  A common voltage VCOM is supplied to the first to eighth common electrode lines CL1 to CL8. The common voltage may be a constant DC voltage, and may not be 0 V, that is, the ground potential (ground potential).

  The first to eighth (mth in a broad sense) common electrode lines CL <b> 1 to CL <b> 8 are commonly connected to the variable capacitance circuit 110.

  The first to twelfth (nth in a broad sense) signal lines DL1 to DL12 are wired along the first direction D1 in the ultrasonic element array 100. Among the first to twelfth signal lines DL1 to DL12, the j-th signal line DLj (j is an integer satisfying 1 ≦ j ≦ 12) is an ultrasonic element arranged in the j-th column of the ultrasonic element array 100. It connects to the 1st electrode which UE has, respectively.

  Specifically, for example, for the ultrasonic element UE11 shown in FIG. 2, the first electrode is connected to the signal line DL1, and the second electrode is connected to the first common electrode line CL1. For example, in the ultrasonic element UE46 shown in FIG. 2, the first electrode is connected to the sixth signal line DL6, and the second electrode is connected to the fourth common electrode line CL4.

  The arrangement of the ultrasonic elements UE is not limited to the m-row / n-column matrix arrangement shown in FIG. For example, a so-called staggered arrangement in which m ultrasonic elements are arranged in an odd-numbered ultrasonic element array and m−1 ultrasonic elements are arranged in an even-numbered ultrasonic element array may be employed.

  During a transmission period in which ultrasonic waves are radiated, first to twelfth drive signals VDR1 to VDR12 for driving the ultrasonic element UE are input to the ultrasonic elements via signal lines DL1 to DL12. Further, during the reception period in which the ultrasonic echo signal is received, the reception signal from the ultrasonic element UE is output via the signal lines DL1 to DL12.

  A voltage difference between the drive signal voltage and the common voltage is applied to each ultrasonic element UE, and ultrasonic waves with a predetermined frequency are emitted. For example, the difference VDR1−VCOM between the drive signal voltage VDR1 supplied to the signal line DL1 and the common voltage VCOM supplied to the common electrode line CL1 is applied to the ultrasonic element UE11 of FIG. Similarly, a difference VDR6-VCOM between the drive signal voltage VDR6 supplied to the signal line DL6 and the common voltage VCOM supplied to the common electrode line CL4 is applied to the ultrasonic element UE46.

  The variable capacitance circuit 110 has a capacitance value (capacitance value) variably set according to the operating state of the ultrasonic apparatus 200. That is, the capacitance value of the variable capacitance circuit 110 is set to a capacitance value corresponding to the operating state of the ultrasonic apparatus 200 based on control of a control unit (not shown). Specifically, during phase scanning of ultrasonic output, the first to twelfth (nth in a broad sense) of the same phase with respect to the first to twelfth (nth in a broad sense) signal lines DL1 to DL12. ) In the first operation state in which the drive signals VDR1 to VDR12 are input, the capacitance value of the variable capacitance circuit 110 is set to the first capacitance value. In the second operation state in which the first to twelfth drive signals VDR1 to VDR12 having different phases are input to the first to twelfth signal lines DL1 to DL12, the capacitance value of the variable capacitance circuit 110 is obtained. Is set to a second capacitance value smaller than the first capacitance value. The phase scanning will be described in detail later.

  More specifically, during phase scanning of ultrasonic output, the first to twelfth drive signals VDR1 to VDR12 are applied to the first to twelfth signal lines DL1 to DL12 in the first to twelfth periods. Entered. Then, the second capacitance value is set according to the overlapping degree of the first to twelfth periods. More specifically, the second capacitance value is set to a larger value as the degree of overlap between the first to twelfth periods is larger.

  Here, the overlap of the first to twelfth periods means that at least a part of two or more periods overlap in time. And the greater the number of overlapping periods, the greater the degree of overlap. For example, when a part of the first period overlaps with a part of the second period, the overlapping degree is 2, and when a part of each of the first, second, and third periods overlaps, the overlapping degree Is 3. Alternatively, the degree of overlap may be considered as the number of ultrasonic elements that are driven simultaneously among 12 ultrasonic elements connected to one common electrode line. For example, when a part of the first period and a part of the second period overlap, there are two ultrasonic elements that are driven simultaneously in the overlapping period, and the first, second, and third periods When a part of each overlaps, three ultrasonic elements are simultaneously driven in the overlapping period.

  One end of the variable capacitance circuit 110 is connected to the first to eighth common electrode lines CL1 to CL8, and a predetermined voltage VA is applied to the other end. The predetermined voltage VA may be a DC voltage and may not be the common voltage VCOM.

  The variable capacitance circuit 110 may include a capacitance element (capacitor) configured by a piezoelectric element (ultrasonic element). By doing so, the capacitive element can be formed on the same substrate as the ultrasonic element array 100. Furthermore, by forming a CMOS transistor or the like on a substrate (silicon substrate), the variable capacitance circuit 110 including a switch element and a capacitive element can be provided on the same substrate as the ultrasonic element array 100.

  Note that a part of the variable capacitance circuit 110 may be provided not in the ultrasonic apparatus 200 but in a connection unit 210 (FIG. 11) or a probe body 230 (FIG. 11) described later.

  As will be described later, by providing the variable capacitance circuit 110, changes in the potentials of the common electrode lines CL1 to CL8 during phase scanning (beam steering) can be suppressed. As a result, it is possible to suppress changes in ultrasonic output (ultrasonic intensity) depending on the beam direction during phase scanning.

  When the phases of the first to twelfth drive signals VDR1 to VDR12 coincide with each other, the ultrasonic waves radiated from the respective ultrasonic elements are synthesized, and the direction perpendicular to the ultrasonic element array 100 (array surface) The ultrasonic wave radiated in the normal direction) is formed. On the other hand, when the drive signals VDR1 to VDR12 have a phase difference with each other, the synthesized ultrasonic wave is radiated in a direction shifted from the normal direction of the array surface according to the phase difference. If this phenomenon is used, the radiation direction of the ultrasonic wave can be changed by changing the phase difference of each drive signal. Scanning the radiation direction (beam direction) of ultrasonic waves by controlling the phase difference of each drive signal is called “phase scanning” or “beam steering”.

  FIG. 3 is a diagram for explaining phase scanning in the ultrasonic apparatus 200 of the present embodiment. For simplicity, FIG. 3 illustrates four ultrasonic elements UE1 to UE4. UE1 to UE4 are arranged at equal intervals d. The phase of the supplied drive signals VDR1 to VDR4 is the fastest in VDR1, and is delayed by a predetermined phase difference in the order of VDR2, VDR3, and VDR4. That is, the drive signals VDR1 to VDR4 are supplied with a predetermined time difference Δt in the order of VDR1, VDR2, VDR3, and VDR4.

FIG. 3 shows wavefronts W1 to W4 of ultrasonic waves emitted from the ultrasonic elements UE1 to UE4 at a certain time. The ultrasonic waves radiated from the respective ultrasonic elements are combined to form a wavefront WT of the combined ultrasonic wave. The normal direction DT of the wavefront WT becomes the synthesized ultrasonic radiation direction (beam direction). The angle θs formed by the beam direction DT and the normal direction of the array surface is
sin θs = c × Δt / d (1)
Given in. Here, c is the speed of sound, Δt is the time difference of the drive signals, and d is the element spacing.

  Thus, the beam direction can be changed by changing the phase difference (time difference) of the drive signals supplied to each ultrasonic element, that is, phase scanning. Specifically, for example, in the configuration example illustrated in FIG. 2, the beam direction is changed along the second direction D2 by changing the phase difference (time difference) of the drive signals VDR1 to VDR12 supplied to the signal lines DL1 to DL12. It can be scanned. That is, the second direction D2 is the scan direction of the phase scanning, and the first direction D1 is the slice direction.

  4A, 4B, and 4C are diagrams for explaining changes in the potentials of the common electrode lines CL1 to CL8 during phase scanning. For simplicity, the six ultrasonic elements UE in the i-th row, the signal lines DL1 to DL6, and the i-th common electrode line CLi will be described.

  FIG. 4A shows an equivalent circuit of the ultrasonic element UE and the common electrode line CLi. The ultrasonic element UE can be electrically regarded as a capacitive element (capacitor) CE. Since the common electrode line CLi has the wiring resistance RCOM, the common voltage VCOM is applied to each ultrasonic element UE via the resistance element RCOM. Since the common electrode line CLi is connected to the signal lines DL1 to DL6 via the capacitance CE of the ultrasonic element UE, the potential of the common electrode line CLi is determined by the drive signals VDR1 to VDR6 input to the signal lines DL1 to DL6. Changes.

  FIG. 4B shows an example of the waveforms of the drive signals VDR1 to VDR6 when front emission, that is, when the ultrasonic beam direction is the normal direction of the array surface (first operation state). At the time of front emission, since the drive signals having the same phase are input at the same timing, the six ultrasonic elements are driven simultaneously. That is, the drive signals VDR1 to VDR6 are input in the first to sixth periods T1 to T6, and the overlapping degree of the first to sixth periods T1 to T6 is 6.

  FIG. 4C shows an example of waveforms of the drive signals VDR1 to VDR6 when the ultrasonic beam direction is a direction shifted from the normal direction of the array surface (second operation state). In this case, the drive signals are input with a phase difference (time difference) from each other. In the periods TB1 and TB3, one ultrasonic element is driven simultaneously, but in the period TB2, two ultrasonic elements are driven simultaneously. That is, the drive signals VDR1 to VDR6 are input in the first to sixth periods T1 to T6, the overlapping degree is 1 in the periods TB1 and TB3, and the overlapping degree is 2 in the period TB2.

  As described above, in the case of the front emission shown in FIG. 4B, since all the ultrasonic elements connected to one common electrode line are driven simultaneously, the potential change (voltage fluctuation) of the common electrode line is growing. On the other hand, when the beam shown in FIG. 4C is tilted, the number of ultrasonic elements that are driven at the same time decreases, so that the potential change (voltage fluctuation) of the common electrode line is smaller than in the case of FIG. Become. In the above description, one common electrode line has been described, but the same applies to the case where there are a plurality of common electrode lines.

  FIG. 5A, FIG. 5B, FIG. 6A, and FIG. 6B show examples of drive signal waveforms and common electrode line voltage fluctuations by circuit simulation. Specifically, the drive signal waveform is the waveform of VDR3 in FIG. 4A, and the voltage of the common electrode line is the voltage of the common electrode node (N3 in FIG. 4A) of the ultrasonic element to which VDR3 is input. V (N3).

  FIG. 5A shows the case of the first steering angle (angle formed by the beam direction and the normal direction of the array surface) θ1, and FIG. 5B shows the second steering angle θ2 (<θ1). FIG. 6A shows the case of front emission (the steering angle is 0).

  As can be seen from FIGS. 5A, 5B, and 6A, the voltage variation of the common electrode line increases as the steering angle decreases. This is because, as described above, the smaller the steering angle, the larger the number of ultrasonic elements that are simultaneously driven, and the larger the steering angle, the smaller the number of simultaneously driven ultrasonic elements.

  FIG. 6B shows a voltage (effective voltage) VDR3-V (N3) applied to the ultrasonic element. When the steering angle is θ1, the effective voltage has the largest amplitude as indicated by A1. In the case of the steering angle θ2 (<θ1), the effective voltage amplitude is smaller than that in the case of θ1 as shown in A2, and in the case of front emission, the effective voltage amplitude is the smallest as shown in A3. . Thus, the smaller the steering angle, the smaller the effective voltage amplitude. Conversely, the larger the steering angle, the larger the effective voltage amplitude.

  When the amplitude of the effective voltage changes with the steering angle, the intensity of the emitted ultrasonic wave changes with the steering angle. For example, when phase scanning is performed by an ultrasonic diagnostic apparatus or the like, the intensity of the echo signal changes depending on the direction because the intensity of the ultrasonic wave radiated changes depending on the beam direction. As a result, there arises a problem that it is difficult to obtain an accurate echo image.

  The ultrasonic apparatus 200 of the present embodiment provides means for solving this problem. According to the ultrasonic apparatus 200 of this embodiment, the variable capacitance circuit 110 is connected to the common electrode line to reduce the change in the intensity of the ultrasonic wave emitted when performing phase scanning, or the intensity is substantially constant. Can be.

  FIG. 7A is a diagram for explaining stabilization of the potential of the common electrode line by the ultrasonic apparatus 200 of the present embodiment. For simplicity, FIG. 7A shows six ultrasonic elements UE, signal lines DL1 to DL6, and i-th common electrode line CLi in the i-th row, but there are a plurality of common electrode lines. But the same is true.

  One end of the variable capacitance circuit 110 is connected to the common electrode line CLi, and a predetermined voltage VA is applied to the other end. The predetermined voltage VA may be a DC voltage and may not be the common voltage VCOM. By making the capacitance value (capacitance value) CA of the variable capacitance circuit 110 sufficiently larger than the coupling capacitance (6 × CE in FIG. 7A) between the common electrode line CLi and the signal lines DL1 to DL6, The potential fluctuation of the electrode line CLi can be suppressed.

  As described above, the number of ultrasonic elements that are driven simultaneously depends on the steering angle. Since the ultrasonic element that is not driven does not affect the potential of the common electrode line CLi, when the number of ultrasonic elements that are driven simultaneously is k, the capacitance value CA of the variable capacitance circuit 110 is sufficiently larger than k × CE. Just make it bigger. In other words, the capacity value CA can be set to the maximum for front emission (the steering angle is 0), and the capacity value CA can be set to be smaller as the steering angle increases.

  In this way, it is possible to avoid setting the capacitance CA of the variable capacitance circuit 110 to an excessively large value exceeding the capacitance value necessary for potential stabilization. As a result, since a transient current for charging / discharging the capacitor CA can be reduced, an increase in power consumption due to the addition of the variable capacitance circuit 110 can be suppressed.

  FIG. 7B shows a first configuration example of the variable capacitance circuit 110 of this embodiment. The variable capacitance circuit 110 of the first configuration example includes a variable capacitance CA and a switch element SW. Note that the variable capacitance circuit 110 of this embodiment is not limited to the configuration of FIG. 7B, and some of the components are omitted, replaced with other components, or other components are added. Various modifications of the above are possible.

  The switch element SW is provided in series with the variable capacitor CA, and is set to an on state during a transmission period and is set to an off state during a reception period. In this way, the variable capacitance circuit 110 is electrically connected to the common electrode line during the transmission period, and is not electrically connected to the common electrode line during the reception period. By doing so, the variable capacitor CA can be electrically disconnected from the common electrode line during the reception period, so that it is possible to prevent a reduction in reception sensitivity when receiving an echo signal. The switch element SW is set to an on state or an off state based on control of a control unit (not shown).

  FIG. 7C shows a second configuration example of the variable capacitance circuit 110 of this embodiment. The variable capacitance circuit 110 of the second configuration example includes first to fifth capacitive elements (capacitors) CA1 to CA5 and first to fifth switch elements SW1 to SW5. Note that the variable capacitance circuit 110 of this embodiment is not limited to the configuration in FIG. 7C, and some of the components are omitted, replaced with other components, or other components are added. Various modifications of the above are possible.

  The first to fifth capacitive elements CA1 to CA5 can be constituted by, for example, piezoelectric elements. By doing so, the capacitive elements CA1 to CA5 can be formed by the same manufacturing process as the ultrasonic element UE, and thus can be formed on the same substrate as the ultrasonic element array 100.

The first to fifth switch elements SW1 to SW5 are provided in series with the first to fifth capacitive elements CA1 to CA5, and the number of ultrasonic elements that are driven simultaneously (in a broad sense, the operating state of the ultrasonic device). Depending on the state, it is set to an on state or an off state. In this way, the capacitance value can be variably set according to the number of ultrasonic elements that are driven simultaneously. The switch elements SW1 to SW5 are set to an on state or an off state based on control of a control unit (not shown). The details of setting the capacitance value by the variable capacitance circuit 110 of the second configuration example will be described later. The switch elements SW and SW1 to SW5 in FIGS. 7B and 7C are realized by, for example, CMOS transistors. Can do. By incorporating a process for forming an ultrasonic element (piezoelectric element) into the CMOS process, the ultrasonic element array 100 and the variable capacitance circuit 110 can be formed on the same substrate.

  The switch elements SW, SW1 to SW5 are on / off controlled by a control unit (not shown). This control unit may be provided in an ultrasonic probe described later, or may be provided in the main body device.

  8A, FIG. 8B, FIG. 9A, and FIG. 9B, the drive signal waveform and the common electrode line by the circuit simulation when the variable capacitance circuit 110 of this embodiment is provided. An example of voltage fluctuation is shown. Specifically, the drive signal waveform is the waveform of VDR3 in FIG. 7A, and the voltage of the common electrode line is the voltage of the common electrode node (N3 in FIG. 7A) of the ultrasonic element to which VDR3 is input. V (N3).

  FIG. 8A shows a case where the capacitor CA is not added to the common electrode line at the same first steering angle θ1 as in FIG. FIG. 8B shows a case where a capacitor CA is added to the common electrode line at the same second steering angle θ2 (<θ1) as in FIG. 5B. FIG. 9A shows a case where CA having a larger capacitance value is added to the common electrode line in the case of front emission (steering angle is 0). As can be seen from FIGS. 8B and 9A, the potential of the common electrode line is stabilized by adding a capacitor CA to the common electrode line.

  FIG. 9B shows a voltage (effective voltage) VDR3-V (N3) applied to the ultrasonic element. It can be seen that by adding the capacitor CA to the common electrode line, the amplitude of the effective voltage becomes almost constant regardless of the steering angle (B1, B2, B3 in FIG. 9B).

  FIG. 10 shows an example of capacitance setting according to the second configuration example (FIG. 7C) of the variable capacitance circuit 110 of the present embodiment. Here, for the sake of simplicity, the case where the drive signals VDR1 to VDR6 are input to the six signal lines DL1 to DL6 as shown in FIG. 7A will be described. In addition, the capacitor elements CA1 to CA5 in FIG. 7C have the same capacitance value.

  FIG. 10 shows the waveforms of the drive signals VDR1 to VDR6, the number of ultrasonic elements driven simultaneously (overlap degree), and the number of capacitive elements connected to the common electrode line in the first to fourth transmission periods TC1 to TC4. Indicates.

  The first transmission period TC1 is the case of front emission (first operation state), and the number of ultrasonic elements that are driven simultaneously (overlap degree) is six. In this case, all of the switch elements SW1 to SW5 in FIG. 7C are set to an on state, whereby all of the capacitor elements CA1 to CA5 are connected to the common electrode line. That is, the number of capacitive elements connected to the common electrode line can be set to 5.

  The second, third, and fourth transmission periods TC2, TC3, and TC4 are cases where drive signals having different phases are input (second operation state), and steering angles are φ2, φ3, and φ4 ( This is the case of φ2 <φ3 <φ4).

  In the second transmission period TC2, the number of ultrasonic elements that are driven simultaneously (overlap degree) is 1 at the beginning of the period, then 2 and then changes to 3, 4, 3, 2, 1 after that. Correspondingly, the number of capacitive elements connected to the common electrode line can be set to 0, 1, 2, 3, 2, 1, 0 by turning on / off the switching elements SW1 to SW5 individually. Can do.

  In the third transmission period TC3, the number of ultrasonic elements that are driven simultaneously (the degree of overlap) is 1 at the beginning of the period, then 2 and then 1. Correspondingly, the number of capacitive elements connected to the common electrode line can be variably set to 0, 1, 0 by individually turning on / off the switching elements SW1 to SW5.

  In the fourth transmission period TC4, the steering angle is further increased, and the number of ultrasonic elements (overlap degree) that are simultaneously driven is 1. Correspondingly, the number of capacitive elements connected to the common electrode line can be set to 0 by setting all the switch elements SW1 to SW5 to the off state.

  Thus, according to the ultrasonic apparatus of the present embodiment, the capacitance value of the capacitor connected to the common electrode line can be variably set according to the number of ultrasonic elements that are driven simultaneously (overlap degree). The capacity value is set to a larger value as the overlapping degree is larger. By doing so, it is possible to reduce the potential fluctuation of the common electrode line, and thus it is possible to suppress changes in the ultrasonic intensity due to the beam direction during phase scanning. As a result, since the ultrasonic intensity can be made constant regardless of the beam direction, it is possible to obtain a highly accurate echo image, for example, with an ultrasonic diagnostic apparatus.

3. Ultrasonic Probe, Electronic Device, Diagnostic Device, and Processing Device FIG. 11 shows a basic configuration example of an ultrasonic probe 300, an electronic device (diagnostic device) 400, and a processing device including the ultrasonic device 200 of this embodiment. The ultrasonic probe 300 includes a probe head 220 and a probe main body 230. The probe head 220 includes an ultrasonic device 200 and a connection unit 210. The probe main body 230 includes a transmission / reception unit and a control unit (ultrasonic probe side control unit) CNTL.

  The processing apparatus also includes a transmission / reception unit that performs transmission / reception processing of the ultrasonic element array 100, a variable capacitance circuit 110, a control unit that performs control of the transmission / reception unit and control of setting the capacitance value of the variable capacitance circuit 110 (ultrasonic probe). Side control unit) CNTL. A part of the control performed by the processing device may be realized by the control unit (main body device side control unit) 310.

  The probe head 220 is detachable through the connection part 210, and can be exchanged according to the diagnosis target. The connection unit 210 is for electrically connecting the ultrasonic apparatus 200 and the probe main body 230, and can be configured by, for example, a flexible substrate and a connector.

  The transmission / reception unit performs transmission / reception processing of the ultrasonic element array 100 and includes a multiplexer MUX, a drive signal generator HV_P, a transmission / reception changeover switch T / R_SW, and an analog front end AFE.

  The multiplexer MUX performs channel switching between the drive signal and the reception signal. For example, when the drive signal generator HV_P, the transmission / reception selector switch T / R_SW, and the analog front end AFE are configured to correspond to signals for eight channels, the multiplexer MUX outputs the signals for the eight channels to the ultrasonic element array 100. Are distributed to the signal lines DL1 to DLn.

  The drive signal generator HV_P generates drive signals VDR1 to VDRn for driving the ultrasonic element UE based on the control of the control unit (ultrasonic probe side control unit) CNTL.

  The transmission / reception change-over switch T / R_SW performs signal switching at the time of transmission and reception. At the time of reception, the multiplexer MUX and the analog front end AFE are electrically connected to output a reception signal from the probe head 220 to the analog front end AFE. At the time of transmission, the multiplexer MUX and the analog front end AFE are electrically disconnected to prevent the drive signal from being input to the analog front end AFE.

  The analog front end AFE performs amplification, gain setting, frequency setting, A / D conversion (analog / digital conversion), and the like of the received signal, and outputs the detection data (detection information) to the processing unit 320. The analog front end AFE can be composed of, for example, a low noise amplifier, a voltage control attenuator, a programmable gain amplifier, a low pass filter, an A / D converter, and the like.

  The control unit (ultrasonic probe side control unit) CNTL controls the transmission / reception unit. Specifically, the phase and frequency of the drive signal are controlled for the drive signal generator HV_P, and the frequency setting of the received signal is controlled for the analog front end AFE. Further, the control unit CNTL performs control for setting the capacitance value of the variable capacitance circuit 110. Specifically, the setting of the capacitance value is controlled by turning on / off the switch element of the variable capacitance circuit 110. The control unit CNTL can be realized by, for example, an FPGA (Field-Programmable Gate Array).

  The control of the transmission / reception unit and the control of setting the capacitance value of the variable capacitance circuit 110 may be performed by the control unit (ultrasonic probe side control unit) CNTL, or the control unit (main body device side control unit) 310. You may go.

  The electronic apparatus 400 is an ultrasonic diagnostic apparatus, for example, and includes an ultrasonic probe 300 and a main body apparatus 410. The main device 410 includes a control unit (main device control unit) 310, a processing unit 320, a UI (user interface) unit 330, and a display unit 340.

  The control unit (main body device side control unit) 310 performs ultrasonic transmission / reception control on the ultrasonic probe 300 and controls the processing unit 320 such as image processing of detection data. The processing unit 320 receives detection data from the analog front end AFE and performs necessary image processing, generation of display image data, and the like. The UI (user interface) unit 330 outputs necessary commands (commands) to the control unit (main body device side control unit) 310 based on an operation (for example, a touch panel operation) performed by the user. The display unit 340 is a liquid crystal display, for example, and displays the display image data from the processing unit 320.

  Although the present embodiment has been described in detail as described above, it will be easily understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention. For example, a term described at least once together with a different term having a broader meaning or the same meaning in the specification or the drawings can be replaced with the different term in any part of the specification or the drawings. The configurations and operations of the ultrasonic device, the ultrasonic probe, the electronic device, the diagnostic device, and the processing device are not limited to those described in this embodiment, and various modifications can be made.

100 ultrasonic element array, 110 variable capacitance circuit, 200 ultrasonic device,
210 connection part, 220 probe head, 230 probe body,
300 ultrasonic probe, 310 control unit (main unit side control unit), 320 processing unit,
330 UI unit, 340 display unit, 400 electronic device, 410 main unit,
UE ultrasonic element, UEC1-12 ultrasonic element row, DL1-DL12 signal line,
CL1 to CL8 common electrode lines, VDR1 to VDR12 drive signals,
VCOM common voltage

Claims (11)

An ultrasonic element array;
Including a variable capacitance circuit,
The ultrasonic element array is:
In each ultrasonic element row, a plurality of ultrasonic elements are arranged along a first direction to a first ultrasonic element row to an n-th (n is an integer of 2 or more) ultrasonic element row;
A first signal line to an nth signal line wired along the first direction;
A first common electrode line wired along a second direction crossing the first direction to an m-th (m is an integer of 2 or more) common electrode line;
The first ultrasonic element array to the nth ultrasonic element array are arranged along the second direction,
Among the first ultrasonic element array to the nth ultrasonic element array, the plurality of ultrasonic elements constituting the jth ultrasonic element array (j is an integer satisfying 1 ≦ j ≦ n). Each of the first electrodes is connected to a jth signal line among the first signal line to the nth signal line,
A second electrode of each of the plurality of ultrasonic elements constituting the j-th ultrasonic element row is connected to any one of the first common electrode line to the m-th common electrode line;
The variable capacitance circuit is commonly connected to the first common electrode line to the m-th common electrode line,
The capacitance value of the variable capacitance circuit is set according to the phase of the first drive signal to the n-th drive signal input to the first signal line to the n-th signal line. An ultrasonic device. The ultrasonic device according to claim 1,
Each ultrasonic element row of the first ultrasonic element row to the nth ultrasonic element row is:
As the plurality of ultrasonic elements,
Having a first ultrasonic element to an m-th ultrasonic element arranged along the first direction,
The second electrode of the i-th ultrasonic element (i is an integer satisfying 1 ≦ i ≦ m) of the first to m-th ultrasonic elements is the first common. An ultrasonic apparatus connected to an i-th common electrode line among electrode lines to the m-th common electrode line. The ultrasonic device according to claim 1 or 2,
During phase scanning of ultrasonic output,
In the first operation state in which the first drive signal to the n-th drive signal having the same phase are input to the first signal line to the n-th signal line, the capacitance value of the variable capacitance circuit is Set to the first capacity value,
In the second operation state in which the first drive signal to the nth drive signal having different phases are input to the first signal line to the nth signal line, the variable capacitance circuit An ultrasonic device characterized in that a capacitance value is set to a second capacitance value smaller than the first capacitance value. The ultrasonic device according to claim 3,
The first driving signal to the n-th driving signal are input to the first signal line to the n-th signal line in the first period to the n-th period, and the first period to the n-th signal line. 2. The ultrasonic apparatus according to claim 1, wherein the second capacitance value of the variable capacitance circuit is set according to the overlapping degree of the n-th period. The ultrasonic device according to claim 4,
The ultrasonic apparatus, wherein the second capacitance value of the variable capacitance circuit is set to a larger value as the degree of overlap between the first period to the nth period is larger. The ultrasonic device according to any one of claims 1 to 5,
The variable capacitance circuit is:
In the transmission period for radiating ultrasonic waves, the first common electrode line to the m-th common electrode line are electrically connected,
An ultrasonic device, wherein the ultrasonic device is electrically disconnected from the first common electrode line to the m-th common electrode line during a reception period for receiving an ultrasonic echo signal. The ultrasonic device according to any one of claims 1 to 6,
The variable capacitance circuit is:
An ultrasonic device comprising a capacitive element composed of a piezoelectric element. Ultrasound probe which comprises an ultrasonic apparatus according to any one of claims 1 to 7. An electronic apparatus comprising the ultrasonic apparatus according to any one of claims 1 to 7. In claim 9,
A control unit that sets a capacitance value of the variable capacitance circuit according to a phase of the first drive signal to the nth drive signal input to the first signal line to the nth signal line. An electronic device comprising: Diagnostic apparatus comprising the ultrasonic apparatus according to any one of claims 1 to 7.

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