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JP2013058900

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DESCRIPTION JP2013058900
Abstract: To provide an electromechanical transducer capable of selectively performing
transmission and reception operations with elements of different shapes. An electromechanical
transducer comprises a plurality of cells each having a diaphragm 101 including a first electrode
102 and a second electrode 105 provided via a gap 104, drive detection means 301, 302, and
setting of a potential difference. Means 303 and switching means 304 are provided. The drive
detection means performs at least one of the transmission function and the reception function.
The first or second element in which the first or second electrodes of the plurality of cells are
electrically connected to each other and connected to the common first or second drive detection
means is configured. At least one of the first and second elements is provided in plurality. The
potential difference setting means sets a predetermined potential difference between the
reference potentials of the first and second drive detecting means, and the switching means sets
the first and second drive detecting means for executing a function at the time of transmission
and reception. Switching between drive detection means of [Selected figure] Figure 1
Electromechanical converter
[0001]
The present invention relates to an electromechanical transducer such as a capacitive
electromechanical transducer that performs transmission and reception (in the present
specification, transmission and reception mean at least one of transmission and reception) of
elastic waves such as ultrasonic waves. About.
[0002]
04-05-2019
1
In order to transmit and receive ultrasonic waves, a capacitive ultrasonic transducer (CMUT)
(Capacitive Micromachined Ultrasonic Transducer) has been proposed.
The CMUT is manufactured using a MEMS (Micro Electro Mechanical Systems) process to which
a semiconductor process is applied. FIG. 10 is a schematic cross-sectional view of the array
CMUT of Non-Patent Document 1. As shown in FIG. In FIG. 10, 101 is a vibrating film, 102 is a
first electrode (upper electrode), 103 is a support portion, 104 is a gap, 105 is a second
electrode (lower electrode), 106 is a substrate, and 107 is an insulating film. . The first electrode
102 is formed on the vibrating membrane 101, and the vibrating membrane 101 is supported by
a support portion 103 formed on the substrate 106 and disposed on the substrate. A second
electrode 105 is disposed on the substrate 106 at a position opposite to the first electrode 102
on the vibrating film 101 with a gap 104 (usually several tens nm to several hundreds nm thick)
interposed therebetween. A structure including first and second electrodes opposed to the
vibrating membrane 101 with the gap 104 therebetween is referred to as a cell 200 as one set.
Either of the first and second electrodes is electrically connected to have a common potential. An
electrode having this common potential is referred to as a common electrode, and here, the
second electrode 105 is described as a common electrode. The second electrode (common
electrode) 105 is connected to the potential difference setting means 121 capable of applying a
desired potential by the wiring 108, and a predetermined direct current potential difference is
set between the second electrode (common electrode) 105 and the opposing first electrode 102.
One of the first and second electrodes which is not the common electrode is electrically
connected to a certain cell group and is equipotential. This cell group is called an element 201 as
a unit of an element that transmits and receives elastic waves. In the following description, an
electrode which is equipotential for each cell group (element) is referred to as a signal electrode,
and here, the first electrode 102 is described as a signal electrode. The first electrode (signal
electrode) 102 of each element is connected to the drive detection means 122 by a wire 109.
Since the insulating film 107 is provided on the substrate 106 to insulate the wiring from the
substrate 106, the wirings of the signal electrodes of different elements and the wirings of the
common electrode are electrically insulated.
[0003]
By operating the drive detection unit 122, at least one of the transmission operation and the
reception operation can be performed. In the transmission operation, the drive detection means
122 generates an alternating voltage, which is applied to the first electrode (signal electrode) to
generate an electrostatic attraction of alternating current between the first and second electrodes
102, 105. This is an operation of vibrating the vibrating membrane 101 integral with the first
04-05-2019
2
electrode 102 and transmitting an elastic wave to the outside. On the other hand, the receiving
operation is an operation of detecting the magnitude of the received elastic wave by receiving the
elastic wave and vibrating the first electrode 102 integral with the vibrating membrane 101. That
is, the capacitance between the first and second electrodes 102 and 105 changes due to the
vibration of the vibrating membrane 101, and the magnitude of the current generated due to the
change of the charge induced to the first electrode (signal electrode) The drive detection means
122 detects the magnitude of the elastic wave.
[0004]
Knight J, McLean J, and Degertekin F L, 2004 "Low temperature fabrication of capacitive
micromachined ultrasonic immersion transducers on silicon and dielectric substrates" (IEEE
Trans. Ultrason., Ferroelect., Freq. Contr. 51 10 1324-1333)
[0005]
In the above configuration, the element as an element unit for transmitting and receiving elastic
waves is determined by the area to which the signal electrode is electrically connected, so the
shape of the element can not be changed. On the other hand, when transmitting and receiving
elastic waves, the optimum shape of the element differs depending on the application (eg,
measurement of elastic waves of different objects). Therefore, it is difficult to say that an
electromechanical transducer having an element whose shape is fixed is easy to use in different
applications.
[0006]
In view of the above problems, the electromechanical transducer according to the present
invention has the following features. This device comprises: a plurality of cells each having a
vibrating film including a second electrode opposed to the first electrode with a gap, drive
detection means, potential difference setting means, and switching means Have. The drive
detection means has a transmission function of generating an alternating current potential
between the first and second electrodes to vibrate the diaphragm, and a reception function of
detecting displacement of the diaphragm by changing the capacitance between the first and
second electrodes. And first and second drive detection means for performing at least one of the
two. A first element is configured to constitute a group of cells in which first electrodes of at least
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3
two of the plurality of cells are electrically connected to each other and connected to a common
first drive detection unit. There is. In addition, the second element is configured such that the
cells formed by electrically connecting the second electrodes of at least two of the plurality of
cells to the common second drive detection unit are one group And a plurality of at least one of
the first and second elements are provided. The potential difference setting means sets a
predetermined potential difference between the reference potentials for performing the
respective functions in the first and second drive detection means, and the switching means
performs the function during the transmission / reception operation. Are switched between the
first and second drive detection means.
[0007]
According to the electromechanical transducer of the present invention, when performing the
transmission and reception operation, the electrodes for exchanging the drive detection signal
are those of the first cell group (first element) and the second cell group (second element). Means
for switching between and operating with the element). Therefore, transmission and reception
operations can be selectively performed with elements of different shapes.
[0008]
It is a figure explaining the electromechanical transducer concerning a 1st embodiment. It is a
figure explaining the electromechanical transducer concerning a 2nd embodiment. It is a figure
explaining the electromechanical transducer concerning a 3rd embodiment. It is a figure
explaining the electric machine converter concerning a 4th and 5th embodiment. It is a figure
explaining the electromechanical transducer concerning a 6th and 7th embodiment. It is a figure
explaining the electromechanical transducer concerning an 8th embodiment. It is a figure
explaining the electromechanical transducer concerning a 9th embodiment. It is a figure
explaining the electric machine converter concerning a 10th embodiment. It is a figure
explaining the electromechanical transducer concerning an 11th embodiment. It is a figure
explaining the conventional electrostatic capacitance type electromechanical transducer.
[0009]
Hereinafter, embodiments of the present invention will be described. The important point in the
present invention is that the drive detection means and the electrode for exchanging the drive
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4
detection signal when performing the transmitting and receiving operation are related to the first
cell group (first element) and the second cell group Switching between the second element) and
operating the device. Based on this idea, the electromechanical transducer of the present
invention has the basic configuration as described in the section for solving the problems.
[0010]
Hereinafter, an embodiment of an electromechanical transducer according to the present
invention will be described in detail with reference to the drawings. First Embodiment FIG. 1 is a
schematic cross-sectional view of an array CMUT according to a first embodiment. In FIG. 1, the
same numbers as those in FIG. 10 described above indicate the same functional elements.
Reference numeral 301 denotes a first drive detection unit, and reference numeral 302 denotes a
second drive detection unit. Reference numeral 303 denotes a potential difference setting means
for setting a potential difference between reference potentials which the first and second drive
detection means respectively have for function execution, and 304 denotes a drive detection
means which operates at the time of transmission and reception. And a switching unit for
switching between the drive detection unit and the second drive detection unit. The first
electrodes are electrically connected to each other in each first group and are at the same
potential. Hereinafter, this group is referred to as a first element 212. Further, the second
electrodes are electrically connected to each other in each second group and are at equal
potential. Hereinafter, this group is referred to as a second element 211. In this embodiment, in
the cell 200 in the area X forming the first element 212 and the cell 200 in the area Y forming
the second element 211, there is a cell that is included in only one of the elements. It is a feature.
In other words, there is a non-overlapping portion in the area X where the first element 212 is
disposed and the area Y where the second element 211 is disposed.
[0011]
The first electrode 102 is drawn to the outside of the substrate 106 by the wiring 109 of the first
electrode for each element 212, and is connected to the first drive detection means 301. The
second electrode 105 is drawn to the outside of the substrate 106 by the wiring 108 of the
second electrode for each element 211, and is connected to the second drive detection means
302. Therefore, the electromechanical transducer of the present embodiment includes the first
drive means 301 by the same number (3 in FIG. 1) as the first elements 212 and the same
number (2 in FIG. 1) as the second elements 211. ), The second drive means 302 is provided. The
drive detection units 301 and 302 respectively have reference potentials V1 and V2 for
operating the electrodes of the elements connected to exchange drive detection signals with
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reference to a predetermined potential. In the plurality of first drive detection means 301, all of
the reference potentials V1 used when generating drive signals and outputting detection signals
are the same potential. Therefore, the potential of the first electrode 102 is usually fixed to the
reference potential V1. Similarly, the reference potentials V2 of the plurality of second drive
detection means 302 are all the same potential. Therefore, the potential of the second electrode
105 is usually fixed at the reference potential V2.
[0012]
The reference potential V1 of the first drive detection means 301 and the reference potential V2
of the second drive detection means 302 are set by the potential difference setting means 303 to
have a predetermined potential difference VB. Therefore, in normal times, the potential V1 of the
first electrode 102 and the potential V2 of the second electrode 105 have a potential difference
VB. When operating the CMUT, a predetermined potential difference VB is applied between the
two electrodes in order to enhance the efficiency of transmission and reception of elastic waves,
and the electrostatic attraction generated between the electrodes causes the diaphragm 101 to
bend toward the substrate 106 side. State. When transmitting an elastic wave, since electrostatic
attraction is in inverse proportion to the square of the distance, it is more efficient if the distance
between the electrodes is reduced. On the other hand, when receiving an elastic wave, the
magnitude of the detected minute current due to the displacement of the vibrating membrane is
inversely proportional to the distance between the electrodes and proportional to the potential
difference between the electrodes. Increasing the potential difference VB results in higher
efficiency. A predetermined potential difference VB can be set between the first and second
electrodes 102 and 105 by the potential difference setting means 303, and an operation with
good transmission / reception efficiency is performed even when transmission / reception
operations are performed with elements of different shapes. be able to.
[0013]
When one of the first and second drive detection means 301 and 302 is performing transmission
and reception drive detection operations, one fixes the potential of the electrode connected
thereto to the reference potential of the drive detection means Perform the action. The switching
means 304 determines which of the first and second drive detection means 301 and 302
performs the transmission / reception operation, switches to the determined one, and the drive
detection means for performing the transmission / reception operation transmits the drive signal.
And capture the detection signal. When the first drive detection unit 301 is selected to perform
transmission and reception operations, application of a drive signal or detection of an induced
04-05-2019
6
current is performed on the first electrode 102 for each first element. The second drive detection
means 302 does not perform the drive detection operation (static), and all the second electrodes
105 facing the first electrode 102 have the reference potential V2. Thus, the second electrode
105 functions as a common electrode having a uniform direct current potential. Therefore, the
transmission and reception operation can be performed with the first element as one unit, and
the shape of the first element is a unit of elements to perform transmission and reception.
[0014]
On the other hand, when the second drive detection unit 302 is selected to perform a drive
detection operation, application of a drive signal or detection of an induced current is performed
on the second electrode 105 for each second element. For the first electrode 102 facing the
second electrode 105, the first drive detection unit 301 does not perform the drive detection
operation (resting), and all have the reference potential V1, and a uniform DC potential Function
as a common electrode. Therefore, the transmission and reception operation can be performed
with the second element as one unit, and the shape of the second element is a unit of the element
performing transmission and reception.
[0015]
In the present invention, the first element and the second element are arranged in different
shapes so as to have non-overlapping portions. Therefore, the shape of the element to be
transmitted and received can be changed between when the first element is an element unit of
transmission and reception and when the second element is an element unit of transmission and
reception. Thus, the electrical connection of the electrodes is fixed by switching the drive
detection means for performing the drive detection operation between the first drive detection
means 301 and the second drive detection means 302 by the switching means 304. Thus,
transmission and reception operations can be performed in units of elements of different shapes.
That is, in the present embodiment, the element shape can be changed only by switching
(selecting) the electrode for exchanging the drive detection signal between the first electrode
group and the second electrode group. Therefore, as compared with a configuration in which a
plurality of wires between the drive detection means and the electrodes are switched by a switch
or the like, characteristic change between the element and the wires is small, and good
transmission / reception characteristics can be obtained.
[0016]
04-05-2019
7
Second Embodiment Next, a second embodiment will be described with reference to FIG. The
second embodiment relates to the configurations of the first drive detection unit 301 and the
second drive detection unit 302. Other than that, it is the same as the first embodiment. In the
present embodiment, the first drive detection unit 301 and the second drive detection unit 302
will be described as the drive detection unit 401, and the reference potential of the drive
detection unit 401 will be described as V3. In addition, an electrode connected to the drive
detection means in operation is described as a signal electrode 402, and the other electrode is
described as a common electrode 403.
[0017]
FIG. 2A is a schematic view for explaining the drive detection means 401 of the present
embodiment. The drive detection unit 401 includes an AC potential generation unit 404 for
driving the CMUT, a current detection unit 405 for detecting a change in capacitance (induction
current) of the CMUT, and a protection switch 406 in order to transmit and receive elastic waves.
. At the time of transmission of the elastic wave, an alternating potential based on the reference
potential V3 is applied to the signal electrode 402 by the alternating potential generation means
404 connected to the signal electrode 402. As a result, an alternating potential difference is
generated between the signal electrode 402 and the common electrode 403, and an alternating
electrostatic attraction is generated in the vibrating membrane 101. At this time, the protection
switch 406 connected to the signal electrode 402 is turned off to protect the input portion of the
current detection means 405 from the potential generated by the AC potential generation means
404. The vibrating film 101 vibrates by the electrostatic attraction generated in this way, and the
CMUT transmits an elastic wave.
[0018]
FIG. 2B is a schematic view for explaining one specific example of the AC potential generating
means 404. As shown in FIG. In the simplest configuration, switches 411 and 412 are disposed
between the output terminal (terminal connected to the signal electrode 402) and the reference
potential V3 and between the output terminal and a predetermined AC voltage potential VP,
thereby generating an AC potential. The means 404 can be realized. Here, the alternating voltage
potential VP is generated based on the reference potential V3. At the time of transmission,
initially, only the switch 412 between the output terminal and the reference potential V3 is
turned on, and the output terminal is at the reference potential V3. While the AC potential is
04-05-2019
8
applied, the switch 412 between the output terminal and the reference potential V3 is turned off,
and the switch 411 between the output terminal and the predetermined AC voltage potential VP
is turned on. After a predetermined time has elapsed, the switch 411 between the output
terminal and the AC voltage potential VP is turned off, the switch 412 between the output
terminal and the reference potential V3 is turned on, and the output terminal is set to the
reference potential V3. Thus, the AC voltage potential VP can be applied to the output terminal
only for a certain period.
[0019]
On the other hand, when receiving an elastic wave, the output terminal of the AC potential
generation means 404 is in a high impedance state (a state where the potential is not fixed), and
does not affect the potential of the signal electrode 402. A high impedance state can be easily
created by turning off (open) all the switches 411 and 412 connected to the output terminal. On
the other hand, the protection switch 406 is turned on, and the signal electrode 402 and the
input portion of the current detection means 405 are connected. At this time, when the
diaphragm 101 vibrates due to an elastic wave applied from the outside, a change in electrostatic
capacitance occurs between the signal electrode 402 and the common electrode 403. Since the
common electrode 403 is fixed at a certain potential and a potential difference VB is generated
between the electrodes, a minute current flows in the wiring of the signal electrode 402 due to
the induced charge generated in the signal electrode 402. By detecting this minute change in
current with the current detection means 405, it is possible to detect the magnitude of the elastic
wave that has caused a change in capacity. At this time, the potential of the signal electrode 402
is substantially fixed to the reference potential V3 by the current detection means 405, and an
operation of extracting only the current is performed. Here, the potential of the signal electrode
402 strictly fluctuates slightly (about several tens of mV at the maximum) at the time of current
detection operation, but compared with the potential difference VB (about several tens V to
several hundreds V) between the electrodes Since the value is very small, the influence on the
change in electrostatic attraction can be ignored.
[0020]
FIG. 2C is a schematic view for explaining one specific example of the current detection means
405. As shown in FIG. The current detection means 405 can be configured by a transimpedance
circuit using an operational amplifier. For the output terminal (OUT) of the operational amplifier
421, the resistor 422 and the capacitor 423 connected in parallel are connected to the inverting
input terminal (-IN), and the output signal is fed back. The non-inverted input terminal (+ IN) of
04-05-2019
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the operational amplifier 421 is connected to the reference potential V3 terminal by a resistor
424 and a capacitor 425 connected in parallel. The positive power supply VDD (not shown) and
the negative power supply VSS (not shown) for supplying power to the operational amplifier 421
set the reference potential terminal to the reference potential V3. With this configuration, the
input current can be taken out as an output voltage without almost changing the potential of the
terminal connected to the signal electrode 402. When the drive detection operation for
transmission and reception is not performed (stationary), the reference potential V3 is directly
applied as a DC potential to the signal electrode 402 by the AC potential generation means 404
(the switch 411 is off, the switch 412 is ON state). At this time, the protection switch 406
connected to the signal electrode 402 is turned off, and the input part of the current detection
means 405 and the signal electrode 402 are not connected.
[0021]
By using the drive detection means of the present embodiment, the drive detection operation of
transmission and reception can be performed or stopped with a simple configuration, and
switching of the element to be operated can be easily performed by the switching means. The
operation when the drive detection operation is not performed (stationary) has been described as
the configuration in which the DC potential is applied by the AC potential generation unit 404,
but the present invention is not limited to this configuration. Alternatively, the AC potential
generation means 404 may be set to a high impedance state, the protection switch 406 may be
turned on, and the current detection means 405 may be fixed to the reference potential V3. That
is, in this configuration, when the switching unit switches to the first drive detection unit during
the transmission / reception operation, the second drive detection unit fixes the second electrode
to the reference potential of the second drive detection unit. . Further, at the same time, the first
drive detection means connects the first electrode to the drive circuit performing the
transmission function of the first drive detection means or the detection circuit performing the
reception function for each first element. On the other hand, when the switching means switches
to the second drive detection means at the time of transmission / reception operation, the first
drive detection means fixes the first electrode to the reference potential of the first drive
detection means. Further, at the same time, the second drive detection means connects the
second electrode to the drive circuit performing the transmission function of the second drive
detection means or the detection circuit performing the reception function for each second
element.
[0022]
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10
Third Embodiment Next, a third embodiment will be described with reference to FIG. The third
embodiment relates to a potential difference setting means 303. Other than that is the same as
any of the said embodiment. The potential difference setting unit 303 of the present embodiment
is characterized by having a DC power supply 431, a level conversion unit 432 of a drive control
signal, and a level conversion unit 433 of a detection signal. In the present invention, there are a
plurality of at least one of the first drive detection means 301 and the second drive detection
means 302, but in order to simplify the explanation, in FIG. 3, the first drive detection means 301
and the second drive detection The means 302 are shown one by one and explained based on
this.
[0023]
The potential difference setting unit 303 needs to operate to generate a predetermined potential
difference VB between the reference potential V1 of the first drive detection unit 301 and the
reference potential V2 of the second drive detection unit 302. For this purpose, two terminals of
the DC power supply 431 are respectively connected to the reference potential terminal 441
(reference potential V1) of the first drive detection means 301 and the reference potential
terminal 442 (reference potential V2) of the second drive detection means 302. Do. Thus, setting
the potential difference VB can be easily realized by controlling the potential difference
generated by the DC power supply 431. Since the first drive detection unit 301 operates based
on the reference potential V1 and the second drive detection unit 302 operates based on the
reference potential V2, a DC potential is applied between the terminals (441, 442) Only by doing
this, a potential difference VB can be generated between the two electrodes 102, 105.
[0024]
Here, for the sake of explanation, it is assumed that the reference potential V0 of the switching
unit 304 is V2. The switching means 304 outputs the respective drive signals 451 and 452 to
the drive detection means 301 and 302, and takes in the respective detection signals 461 and
462 from the drive detection means 301 and 302. The drive signal 451 is converted (level
shifted) to the drive signal 453 by raising the reference potential by VB by the level conversion
means 432 of the drive control signal. The level-shifted drive signal 453 is input to the first drive
detection unit 301 as a signal for controlling the drive. Further, the detection signal 461 output
from the first drive detection unit 301 is converted (level shift) into the detection signal 463 by
lowering the reference potential by VB by the level conversion unit 433 of the detection signal.
04-05-2019
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[0025]
Since the reference potentials of the first and second drive detection units 301 and 302 are set to
be different by the potential difference setting unit 303, the level of the signal exchanged by the
drive detection unit is shifted by the potential difference VB. The potential difference VB is a few
tens of volts to a few hundreds of volts, which is a very large value as compared with a normal
digital control signal or analog signal. Therefore, when exchanging the control signal and the
detection signal with the switching means 304 with the reference potential V1 or V2 (which is
also V0 in this description) as the reference potential, the signal level shift becomes large and the
exchange is not successful. In the present embodiment, a level conversion unit 432 of the drive
control signal and a level conversion unit 433 of the detection signal are provided. Therefore,
based on the reference potential of the switching unit 304, the drive control signals 453, 452
and the detection signals 463, 462 can be easily exchanged. According to this embodiment,
different reference potentials can be easily generated by using a DC power supply and a plurality
of level shift means, and the exchange of input / output signals with the outside can be
performed smoothly. It can be surely performed by means 304.
[0026]
Fourth Embodiment Next, a fourth embodiment will be described using FIG. 4 (a). The fourth
embodiment relates to the switching means 304. Other than that is the same as any of the first to
third embodiments. FIG. 4A is a schematic view for explaining the switching means 304. 471 is a
first signal generation means, 472 is a second signal generation means, 473 is a first detection
signal acquisition means, 474 is a second detection signal acquisition means, 481 is a drive
control switching means, and 482 is a signal selection means , 491 is a selection signal, and 492
is a selection detection signal. The switching means 304 is a group of the first electrodes (for the
first element) and the second electrode, which exchange driving detection signals when
performing transmission / reception operation based on the selection signal 491 inputted from
the outside. Switch between a group of electrodes (of the second element).
[0027]
First, the case where the transmission and reception operation is performed in the first element
will be described. In FIG. 4A, when the selection signal 491 for selecting the operation by the first
element is input to the switching unit 304, the drive control switching unit 481 outputs
command signals 493 and 494. The command signal 493 to the first signal generation unit 471
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instructs the first drive detection unit 301 to perform transmission and reception operations, and
the drive control signal 451 (see 453 in FIG. 3) in the first signal generation unit 471. Generate
On the other hand, the command signal 494 to the second signal generation unit 472 instructs
the second drive detection unit 302 to keep the stationary state, and the second signal
generation unit 472 generates the drive control signal 452. Further, the signal selection means
482 which has received the selection signal 491 which has selected the operation of the first
element selects the detection signal 463 (461, see FIG. 3) outputted from the first drive detection
means 301, Output as the selection detection signal 492. On the other hand, the detection signal
462 output from the second drive detection unit 302 is input to the signal selection unit 482, but
is not output to the outside.
[0028]
Similarly, the case where the transmission and reception operation is performed in the second
element will be described. When the selection signal 491 for selecting the operation of the
second element is input to the switching unit 304, the drive control switching unit 481 outputs
command signals 493 and 494. The command signal 493 to the first signal generation unit 471
instructs the first drive detection unit 301 to maintain the stationary state, and the first signal
generation unit 451 generates the drive control signal 451 (453). On the other hand, a command
signal 494 to the second signal generation unit 472 instructs the second drive detection unit 302
to perform transmission and reception operations, and the second signal generation unit 472
generates a drive control signal 452. Further, the signal selection means 482 which has received
the selection signal 491 which has selected the operation of the second element selects the
detection signal 462 outputted from the second drive detection means 302 and outputs it as the
selection detection signal 492 to the outside. Do. On the other hand, although the detection
signal 463 (461) output from the first drive detection unit 301 is input to the signal selection
unit 482, it is not output to the outside.
[0029]
As described above, by performing the switching operation of the drive detection signal using the
switching unit 304 of this embodiment, the element performing the transmission / reception
operation is switched between the first element and the second element to perform transmission
/ reception. It can work.
[0030]
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Fifth Embodiment Next, a fifth embodiment will be described using FIG. 4 (b).
The fifth embodiment relates to the processing of the detection signal in the switching means
304. Other than that is the same as the fourth embodiment. The present embodiment is
characterized in that the switching unit 304 has a polarity inverting unit 475 of the detection
signal. The polarity inverting means 475 inverts the polarity of the detection signal 463 (461)
with the reference potential V2 as the center, and outputs it as a polarity inversion detection
signal 464. The polarity inversion detection signal 464 is input to the signal selection unit 482
instead of the detection signal 463 (461) output from the first drive detection unit 301.
[0031]
Even when the diaphragm 101 vibrates in the same manner by elastic waves, the polarity
inverting means 475 aligns the detection signal 463 (461) from the first element and the
detection signal 462 from the second element to the same polarity. Can. In the present invention,
a predetermined potential difference VB is provided between the reference potentials of the first
element and the second element. Here, it is assumed that the potential V1 of the first element is
higher than the potential V2 of the second element by VB. Then, the potential of the first element
when viewed with the second element as a reference is + VB, the potential of the second element
when viewed with the first element as a reference is -VB, and the polarity is reversed. . When an
elastic wave is received, the detected minute current is proportional to the potential difference
VB between the electrodes, so that when the potential difference has a different polarity, a
detection signal whose polarity is reversed is output. In this embodiment, since the switching
means 304 has the polarity inverting means 475, the polarities of the output signal 461 from the
first element and the output signal 462 from the second element can be made the same.
[0032]
In the present embodiment, the polarity reversing unit 475 is described as being included in the
switching unit 304. However, the present invention is not limited to this. The polarity reversing
means 475 can also be configured as the first drive detection means 301 or the second drive
detection means 302 has. Further, it may be configured to have the potential difference setting
means 303 and the level conversion means 433 (see FIG. 3) of the detection signal therein.
Furthermore, the configuration may be such that the means for exchanging the selection signal
491 and the selection detection signal 492 with the electromechanical transducer itself is
included.
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[0033]
Sixth Embodiment Next, the sixth embodiment will be described with reference to FIG. The sixth
embodiment relates to an element shape. Other than that is the same as any one of the first to
fifth embodiments. FIG. 5A is a view schematically showing the area X of the first element and
the area Y (area of oblique lines) of the second element when viewed from the upper surface
direction of the substrate 106. In FIG. 5A, in order to make the drawing easy to see, the end of
the area of X and the end of the area of Y are slightly shifted, but they actually coincide.
[0034]
The first element area X is rectangular and arranged in one dimension, and the area Y of the
second element is arranged in a large rectangular shape and one dimension. Each element is
composed of, for example, a plurality of two-dimensionally arranged cells (each having first and
second electrodes provided with a gap). Here, the width of the short side of the first element is
narrower than the width of the short side of the second element. By switching the transmission /
reception operation between the first element and the second element, the transmission /
reception operation can be performed by a one-dimensional array of elements of different
widths. That is, the optimum width of the one-dimensional array changes according to the
frequency domain of the elastic wave to be transmitted / received, and in this embodiment, the
width of the element can be switched in accordance with the frequency to be used. As described
above, according to the present embodiment, it is possible to provide a capacitive
electromechanical transducer capable of switching the widths of the elements of the onedimensional array to be transmitted and received in accordance with the frequency of the elastic
wave to be transmitted and received.
[0035]
Seventh Embodiment Next, the seventh embodiment will be described with reference to FIG. The
seventh embodiment also relates to the element shape. Other than that is the same as any one of
the first to fifth embodiments. FIG. 5B is also a view schematically showing the first element
region X and the second element region Y (hatched region) when viewed from the upper surface
direction of the substrate 106. Although FIG. 5B also illustrates the ends of the X region and the
Y region slightly offset in order to make the drawing easy to see, they actually coincide with each
04-05-2019
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other.
[0036]
In the present embodiment, the plurality of first element regions X provided in a rectangular
shape are one-dimensionally disposed, and the plurality of second element regions Y provided in
the same manner are rectangular, and the long side direction thereof is a region X It is arranged
in one dimension so as to be orthogonal to the long side direction. By switching the element
performing transmission / reception operation between the orthogonal first element and second
element, the transmission / reception operation of the one-dimensional array can be performed
by switching the transmission / reception direction of the elastic wave. As described above,
according to the present embodiment, it is possible to provide a capacitive electromechanical
transducer capable of switching the array direction of the elements of the one-dimensional array
to be operated for transmission and reception.
[0037]
Eighth Embodiment Next, an eighth embodiment will be described with reference to FIG. The
eighth embodiment also relates to the element shape. Other than that is the same as any one of
the first to fifth embodiments. FIG. 6 is also a view schematically showing the first element region
X and the second element region Y (hatched region) when viewed from the upper surface
direction of the substrate 106. In FIG. 6 as well, in order to make the drawing easy to see, the
ends of the X area and the Y area are slightly shifted, but they actually coincide.
[0038]
The first element area X is arranged in a square shape in two dimensions, and the second
element area Y is arranged in a rectangular shape in one dimension. By switching the elements
that perform transmission and reception between the first element and the second element,
transmission and reception between elements of the two-dimensional array and elements of the
one-dimensional array in the same capacitive electromechanical transducer The operation can be
switched. Thus, according to the present embodiment, it is possible to provide a capacitive
electromechanical transducer capable of switching between transmission and reception
operations by a two-dimensional array and a one-dimensional array.
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[0039]
Ninth Embodiment Next, a ninth embodiment will be described with reference to FIG. The ninth
embodiment relates to a drive detection means. Other than that is the same as any of the first to
eighth embodiments. In the drive detection unit of the present embodiment, the first drive
detection unit 301 can perform only the reception operation, and the second drive detection unit
302 can perform the transmission and reception operation.
[0040]
When the first element is selected to operate, the first element receives an elastic wave input
from the outside. At this time, since the first drive detection unit 301 performs only the reception
operation, the number of components can be reduced. Specifically, it is not necessary to include
the AC potential generating means 404 described in the second embodiment, and in some cases,
a configuration without the protection switch 406 can be used. On the other hand, the operation
at the time of performing the transmission / reception operation in the second element and the
configuration are the same as in the other embodiments.
[0041]
In addition, it is desirable that the reference potential of the drive detection unit 302 of the
element performing transmission and reception be matched with the reference potential V0 of
the switching unit 304. Therefore, in the present embodiment, the reference potential V0 of the
switching unit 304 is made to coincide with the reference potential V2 of the second drive
detection unit 302. As a result, the configuration of the level conversion means 432 of the drive
control signal provided in the potential difference setting means 303 can be simplified or
omitted. According to the present embodiment, one of the elements is configured to perform only
the reception operation, so a capacitive type electromechanical transducer capable of exchanging
a drive detection signal at a higher speed and performing a switching operation with a simpler
configuration. Can be provided.
[0042]
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17
Tenth Embodiment Next, the tenth embodiment will be described with reference to FIG. The tenth
embodiment relates to an ultrasonic measurement apparatus using the electromechanical
transducer according to any one of the first to ninth embodiments. In FIG. 8A, 500 is an
ultrasonic measurement device, 502 is a measurement object, 503 is a capacitance type
electromechanical transducer, 504 is an image information generation device, and 505 is an
image display. Also, 511 and 512 are ultrasonic waves, 513 is ultrasonic wave transmission
information, 514 is an ultrasonic wave reception signal, and 515 is reproduction image
information.
[0043]
The ultrasonic wave 511 by the transmission signal output from the electromechanical
transducer 503 toward the measurement object 502 is reflected on the surface of the
measurement object 502 due to the difference in specific acoustic impedance at the interface.
The reflected ultrasonic wave 512 is received by the electromechanical transducer 503, and
information on the size, shape, and time of the received signal is sent to the image information
generation device 504 as an ultrasonic wave received signal 514. On the other hand, information
of the size, shape, and time of transmission ultrasonic waves (that is, the transmission signal) is
sent from the electromechanical conversion device 503 to the image information generation
device 504 as ultrasonic transmission information 513. The image information generation device
504 generates an image signal of the measurement object 502 based on the ultrasonic wave
reception signal 514 and the ultrasonic wave transmission information 513, sends it as the
reproduction image information 515, and displays it on the image display 505.
[0044]
The CMUT described in any of the above embodiments is used for the capacitance type
electromechanical transducer 503 of this embodiment. Thus, transmission and reception
operations can be performed by switching between elements of different shapes, so that
transmission and reception operations can be performed in an optimal element shape in
accordance with the measurement object 502. Therefore, more accurate information of the
ultrasonic wave 512 reflected by the measurement object 502 can be obtained, and the image of
the measurement object 502 can be reproduced more accurately. Note that the present
embodiment is not limited to the above configuration, and as shown in FIG. 8B, another
ultrasonic wave transmitter (elastic wave transmitter) 501 and an electromechanical transducer
according to the present invention (elasticity (elasticity) The wave receiver 503 may be
combined.
04-05-2019
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[0045]
Eleventh Embodiment Next, an eleventh embodiment will be described with reference to FIG. The
eleventh embodiment relates to an ultrasonic measurement device using a photoacoustic effect
using the capacitance type electromechanical transducer described in the eighth and ninth
embodiments. In FIG. 9, 600 is an ultrasonic measurement device, 602 is a measurement object,
603 is a capacitance type electromechanical transducer, 604 is a first image information
generation device by photoacoustic signal, and 605 is a second by ultrasonic transmission /
reception And an image display unit 606. Further, 611 is a light source, 621 is a light emission
instruction signal, 622 is light, 623 is an ultrasonic wave by the photoacoustic signal, 624 is an
ultrasonic wave reception signal of the photoacoustic signal, and 625 is a reproduced image
information by the photoacoustic signal. Also, 631 is an ultrasonic wave to be transmitted, 632 is
an ultrasonic wave to be received, 633 is ultrasonic wave transmission information, 634 is an
ultrasonic wave reception signal by ultrasonic wave transmission and reception, and 635 is
reproduced image information by ultrasonic wave transmission and reception.
[0046]
The ultrasonic measurement apparatus 600 of the present embodiment is characterized in that
ultrasonic measurement using the photoacoustic effect and ultrasonic measurement using the
transmitted ultrasonic wave are performed using the same electromechanical transducer 603. By
using the electro-mechanical transducer according to the eighth and ninth embodiments, it is
possible to switch between ultrasonic measurement using the photoacoustic effect and ultrasonic
measurement using the transmitted ultrasonic wave. . In the electromechanical transducer 603 of
the present embodiment, the first elements are arranged in a square shape in a two-dimensional
manner, and the first drive detection means 301 can perform only the reception operation, and
the second element Are arranged in one dimension in a rectangular shape, and the second drive
detection means 302 can perform transmission and reception operations (see FIGS. 6 and 7).
[0047]
First, ultrasonic measurement using the photoacoustic effect will be described. The switching
means 304 selects the first element arranged as a two-dimensional array to perform a detection
operation. The light 622 is emitted to the measurement target 602 by generating light 622
04-05-2019
19
(pulsed light) from the light source 611 based on the light emission instruction signal 621. In the
measuring object 602, the irradiation of the light 622 generates an acoustic wave (ultrasonic
wave) 623. The ultrasonic wave 623 is received by the electromechanical transducer 603 having
an element of a two-dimensional array. Information on the size, shape, and time of the reception
signal is sent to the image information generation device 604 as an ultrasonic reception signal
624. On the other hand, a light emission instruction signal 621 having information on the size,
shape, and time of the light 622 generated by the light source 611 is input to the image
information generating device 604 of the photoacoustic signal. The image information
generation apparatus 604 of the photoacoustic signal generates an image signal of the
measurement object 502 based on the ultrasonic wave reception signal 624 and the light
emission instruction signal 621, and outputs it as the reproduced image information 625 based
on the photoacoustic signal.
[0048]
Next, ultrasonic measurement using the transmitted ultrasonic wave will be described. The
switching means 304 selects the second element arranged as a one-dimensional array to perform
transmission and reception operations. The ultrasonic wave 631 is output (sent) from the
electromechanical transducer 603 toward the measurement object 602. Ultrasonic waves are
reflected on the surface of the measurement object 602 due to the difference in specific acoustic
impedance at the interface. The reflected ultrasonic wave 632 is received by the
electromechanical transducer 603, and information on the size, shape, and time of the received
signal is sent to the image information generator 605 as an ultrasonic wave received signal 634.
On the other hand, information of the size, shape, and time of transmission ultrasonic waves is
sent from the electromechanical conversion device 603 to the image information generation
device 605 by ultrasonic transmission / reception as ultrasonic transmission information 633.
The image information generation device 605 generates an image signal of the measurement
object 602 based on the ultrasonic wave reception signal 634 and the ultrasonic wave
transmission information 633, and outputs the image signal as reproduction image information
635 by ultrasonic wave transmission and reception. The image display 605 displays the
measurement object 602 as an image based on the reproduced image information 625 based on
the input photoacoustic signal and the reproduced image information 635 based on ultrasonic
wave transmission and reception.
[0049]
The ultrasonic measurement device 603 according to the present embodiment uses an
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20
electromechanical transducer 603 capable of performing transmission and reception operations
by switching between elements of different shapes. Therefore, ultrasonic measurement using the
photoacoustic effect and ultrasonic measurement using the transmitted ultrasonic wave can be
performed using the same electromechanical transducer 603. Therefore, the ultrasonic
measurement on the measurement object 602 can be performed by a plurality of methods
without changing the positional relationship between the commonly used electromechanical
transducer 603 and the measurement object 602. Therefore, more detailed information can be
obtained for the measurement object 602, and the image can be reproduced more accurately.
[0050]
101 · · · vibrating membrane, 102 · · first electrode (upper electrode), 104 · · · gap, 105 · · second
electrode (lower electrode), 301 · · first drive detection means, 302 · · second Drive detection
means, 303 · · · Potential difference setting means, 304 · · · Switching means
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