Patent Publication Number: US-2021162463-A1

Title: Ultrasonic device

Description:
The present application is based on, and claims priority from JP Application Serial Number 2019-216434, filed Nov. 29, 2019, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an ultrasonic device. 
     2. Related Art 
     In the past, there has been known an ultrasonic device for transmitting/receiving an ultrasonic wave (e.g., JP-A-2008-99103 (Document 1)). The ultrasonic device in Document 1 is provided with a receiving member and a plurality of receiving elements fixed to the receiving member. The receiving member has a plurality of receiving areas, and between these receiving areas, there are formed shield sections (concave grooves). Thus, the crosstalk between the receiving areas adjacent to each other is prevented. Further, receiving elements independent of each other are respectively disposed in the receiving areas. 
     However, in the ultrasonic device of Document 1, there is a problem that the strength is weakened at the formation positions of the concave grooves in the receiving member. Further, since there is adopted the configuration in which the concave groove is disposed between the receiving areas adjacent to each other, and at the same, the receiving elements independent of each other are respectively disposed in the receiving areas, there is a problem that the configuration also becomes complicated. 
     SUMMARY 
     An ultrasonic device according to a first aspect includes a substrate having a plurality of opening parts, and a wall disposed between the opening parts adjacent to each other, a vibrating plate configured to close the opening parts, and vibrators provided to the vibrating plate at positions overlapping the opening parts when viewed from a stacking direction of the substrate and the vibrating plate, wherein the plurality of opening parts includes a first opening part, a second opening part adjacent to the first opening part via a first wall, and a third opening part adjacent to the first opening part via a second wall, a first vibrating section configured to close the first opening part in the vibrating plate and the vibrator disposed in the first vibrating section constitute a first ultrasonic transmitter configured to transmit an ultrasonic wave, a second vibrating section configured to close the second opening part in the vibrating plate and the vibrator disposed in the second vibrating section constitute an ultrasonic receiver configured to receive an ultrasonic wave, a third vibrating section configured to close the third opening part in the vibrating plate and the vibrator disposed in the third vibrating section constitute a second ultrasonic transmitter configured to transmit an ultrasonic wave, and a width of the first wall from the first opening part to the second opening part is larger than a width of the second wall from the first opening part to the third opening part. 
     An ultrasonic device according to a second aspect includes a vibrating plate, a protective member having a protruding part bonded to the vibrating plate and configured to divide the vibrating plate into a plurality of vibrating sections, and vibrators disposed in the respective vibrating sections of the vibrating plate, wherein the plurality of vibrating sections includes a fourth vibrating section, a fifth vibrating section adjacent to the fourth vibrating section via a first protruding part, and a sixth vibrating section adjacent to the fourth vibrating section via a second protruding part, the fourth vibrating section and the vibrator disposed in the fourth vibrating section constitute a third ultrasonic transmitter configured to transmit an ultrasonic wave, the fifth vibrating section and the vibrator disposed in the fifth vibrating section constitute an ultrasonic receiver configured to receive an ultrasonic wave, the sixth vibrating section and the vibrator disposed in the sixth vibrating section constitute a fourth ultrasonic transmitter configured to transmit an ultrasonic wave, and a width of the first protruding part from the fourth vibrating section to the fifth vibrating section is larger than a width of the second protruding part from the fourth vibrating section to the sixth vibrating section. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing a schematic configuration of an ultrasonic apparatus according to an embodiment. 
         FIG. 2  is a cross-sectional view of an ultrasonic device cut along the line A-A shown in  FIG. 1 . 
         FIG. 3  is a cross-sectional view of the ultrasonic device cut along the line B-B shown in  FIG. 1 . 
         FIG. 4  is a diagram showing a relationship between the wall width of a wall and the crosstalk ratio in the present embodiment. 
         FIG. 5  is a diagram showing the relationship between the wall width of the wall and the crosstalk ratio in the present embodiment with respect to each of the cases of setting the wall length of the wall to 50 μm, 70 μm, and 90 μm, respectively. 
         FIG. 6  is a diagram showing a relationship between the wall width of a protruding part and the crosstalk ratio in the present embodiment. 
         FIG. 7  is a diagram showing the relationship between the protruding part wall width and the crosstalk ratio in the present embodiment with respect to each of the cases of setting the protruding part wall length to 50 μm, 70 μm, and 90 μm, respectively. 
     
    
    
     DESCRIPTION OF AN EXEMPLARY EMBODIMENT 
     An embodiment of the present disclosure will hereinafter be described. 
       FIG. 1  is a diagram showing a schematic configuration of an ultrasonic apparatus  100  according to the present embodiment. 
     As shown in  FIG. 1 , the ultrasonic apparatus  100  is configured including an ultrasonic device  10  and a control device  60 . 
     Such an ultrasonic apparatus  100  can be used as a range sensor and a thickness detection sensor by transmitting an ultrasonic wave from the ultrasonic device  10  to an object not shown, and then receiving the ultrasonic wave reflected by the object. For example, when using the ultrasonic apparatus  100  as the range sensor, the control section  60  measures the time from a transmission timing of the ultrasonic wave from the ultrasonic device  10  to a reception timing when the ultrasonic wave reflected by the object is received by the ultrasonic device  10 . Thus, the control section  60  calculates the distance of the object from the ultrasonic device  10  based on the time thus measured and the known speed of sound. Further, when using the ultrasonic apparatus  100  as the thickness detection sensor, the control section  60  transmits an ultrasonic wave from the ultrasonic device  10  to the object, and then measures the sound pressure of the ultrasonic wave reflected by the object and then received by the ultrasonic device  10 . Thus, it is possible for the control section  60  to detect the thickness of the object and overlap of the object based on the sound pressure. 
     Constituents of such an ultrasonic apparatus  100  will hereinafter be described. 
     Configuration of Ultrasonic Device  10   
       FIG. 2  is a cross-sectional view of the ultrasonic device  10  cut along the line A-A shown in  FIG. 1 .  FIG. 3  is a cross-sectional view of the ultrasonic device  10  cut along the line B-B shown in  FIG. 1 . 
     As shown in  FIG. 1 , the ultrasonic device  10  is provided with transmission channels CH O  for transmitting the ultrasonic wave, and a reception channel CH I  for receiving the ultrasonic wave. In the present embodiment, there are disposed eight transmission channels CH O  around the reception channel CH I . Each of the channels is an element group to be driven individually. For example, one transmission channel CH O  includes a plurality of ultrasonic transmitters  11  arranged in a two-dimensional array structure. By signal lines of these ultrasonic transmitters  11  being coupled to each other, it becomes possible to simultaneously drive the ultrasonic transmitters  11  included in one transmission channel CH O . In other words, in the ultrasonic device according to the present embodiment, it becomes possible to drive the eight transmission channels CH O  independently of each other. 
     The same applies to the reception channel CH I , and the reception channel CH I  includes a plurality of ultrasonic receivers  12  arranged in a two-dimensional array structure. 
     As shown in  FIG. 2  and  FIG. 3 , the ultrasonic device  10  is configured including a substrate  20 , a vibrating plate  30  stacked on the substrate  20 , piezoelectric elements  40  (vibrators) provided to the vibrating plate  30 , and a protective member  50  for covering the substrate  20 , the vibrating plate  30 , and the piezoelectric elements  40 . Here, a stacking direction from the protective member  50  toward the vibrating plate  30  and the substrate  20  is defined as a Z direction. Further, a direction perpendicular to the Z direction is defined as an X direction, and a direction perpendicular to the X direction and the Z direction is defined as a Y direction. 
     As shown in  FIG. 2  and  FIG. 3 , the substrate  20  is a member for supporting the vibrating plate  30 , and is formed of a semiconductor substrate made of Si or the like. The substrate  20  is provided with a plurality of opening parts  21  penetrating along the Z direction. The opening parts  21  are each formed so as to elongate in the X direction as shown in  FIG. 3 , and are arranged along the Y direction as shown in  FIG. 2 . In other words, in the substrate  20 , between the opening parts  21  adjacent to each other in the Y direction, there is disposed a wall  22 . 
     It should be noted that the wall width and the wall length of each of the walls  22  will be described later. 
     The vibrating plate  30  is formed of, for example, stacked body made of SiO 2  and ZrO 2 . The vibrating plate  30  is supported by the substrate  20 , and closes the −Z side of the opening part  21 . 
     The protective member  50  is a member which is bonded to a surface at the opposite side to the substrate  20  of the vibrating plate  30  to reinforce the substrate  20  and the vibrating plate  30 . The protective member  50  is provided with a base part  51  shaped like a substrate, and protruding parts  52  protruding from the base part  51  toward the vibrating plate  30 . 
     The protruding parts  52  are each formed so as to elongate in the Y direction as shown in  FIG. 2 , and are arranged along the X direction as shown in  FIG. 3 . The protruding tip of the protruding part  52  is bonded to the vibrating plate  30  with a bonding member such as silicone. In other words, the base part  51  and the protruding parts  52  form recessed parts  53 . 
     It should be noted that in  FIG. 3 , there is shown an example in which the base part  51  and the protruding parts  52  have an integral configuration, but it is also possible to adopt a configuration in which the base part  51  and the protruding parts  52  are separate members, and the protruding parts  52  are bonded to the base part  51 . 
     In such a configuration, in the vibrating plate  30 , an area overlapping the opening part  21  when viewed from the Z direction is zoned by the plurality of protruding parts  52  into a plurality of areas. In other words, in the vibrating plate  30 , the vibrating sections  31  are each formed by an area surrounded by edges (edges of the walls  22 ) of the opening parts  21 , and edges of the protruding parts  52 . 
     As described above, in the present embodiment, the plurality of opening parts  21  each elongating in the X direction is arranged along the Y direction, and the plurality of protruding parts  52  each elongating in the Y direction is arranged along the X direction. Therefore, these vibrating sections  31  line in the X direction and the Y direction, and are arranged in a two-dimensional array structure. In other words, the transmission channels CH O  and the reception channel CH I  each have the vibrating sections  31  arranged in a two-dimensional array structure in which the vibrating sections  31  line in the X direction and the Y direction. Further, the vibrating sections  31  arranged along the X direction in one transmission channel CH O  and the vibrating sections  31  arranged along the X direction in another transmission channel CH O  adjacent to this transmission channel CH O  line along the X direction. Similarly, the vibrating sections  31  arranged along the X direction in one transmission channel CH O  and the vibrating sections  31  arranged along the X direction in the reception channel CH I  adjacent to this transmission channel CH O  line along the X direction. The same applies to the Y direction. 
     The piezoelectric elements  40  are respectively disposed with respect to the vibrating sections  31  of the vibrating plate  30 . The piezoelectric elements  40  are each a vibrator for vibrating the vibrating section  31 . Although the illustration of the detailed configuration of the piezoelectric element  40  is omitted, the piezoelectric element  40  is configured by, for example, stacking a lower part electrode, a piezoelectric film, and an upper part electrode in sequence on the vibrating plate  30 . Further, the signal lines are coupled to the respective lower part electrodes and the respective upper part electrodes. These signal lines are electrically coupled to the control section  60  via terminal parts provided to the vibrating plate  30 , and thus, due to the control from the control section  60 , the transmission channels CH O  and the reception channel CH I  are driven. 
     Here, one vibrating section  31  in the transmission channel CH O  and the piezoelectric element  40  disposed on that vibrating section  31  constitute one ultrasonic transmitter  11 . Further, one vibrating section  31  in the reception channel CH I  and the piezoelectric element  40  disposed on that vibrating section  31  constitute one ultrasonic receiver  12 . 
     The lower part electrodes of the plurality of ultrasonic transmitters  11  arranged in the same transmission channel CH O  are coupled to each other with the signal lines. Similarly, the upper part electrodes of the plurality of ultrasonic transmitters  11  arranged in the same transmission channel CH O  are coupled to each other with the signal lines. Thus, by, for example, inputting a bias signal to the signal lines to be coupled to the lower part electrodes, and inputting a drive signal to the signal lines to be coupled to the upper part electrodes, it becomes possible to simultaneously drive the ultrasonic transmitters  11  included in one transmission channel CH O . In other words, by applying a voltage between the lower part electrode and the upper part electrode in the piezoelectric element of each of the ultrasonic transmitters  11 , the piezoelectric film expands or contracts, and thus, the vibrating section  31  vibrates with an oscillation frequency corresponding to the opening width and so on of the opening part  21 . Thus, the ultrasonic wave is transmitted from the transmission channel CH O  toward the +Z side. 
     Further, the lower part electrodes of the plurality of ultrasonic receivers  12  arranged in the reception channel CH I  are coupled to each other with the signal lines, and the upper part electrodes of the plurality of ultrasonic receivers  12  arranged in the reception channel CH I  are coupled to each other with the signal lines. Thus, when the ultrasonic wave is received by the reception channel CH I , the vibrating section  31  of each of the ultrasonic receivers  12  vibrates, and a potential difference is generated between the lower part electrode side of the piezoelectric film and the upper part electrode side thereof. Therefore, a reception signal having a signal voltage corresponding to the potential difference is output from the reception channel CH I , and it is possible for the control section  60  to detect the signal of the ultrasonic wave. 
     Configuration of Control Section  60   
     The control section  60  is provided with, for example, a drive circuit for driving the ultrasonic device  10 , and a control circuit for controlling an overall operation of the ultrasonic apparatus  100 . 
     The drive circuit is provided with, for example, a transmission circuit for outputting drive signals (voltage signals) to be output to the transmission channels CH O  of the ultrasonic device  10 , and a reception circuit for performing signal processing on a reception signal input from the reception channel CH I . 
     The control circuit is formed of, for example, a microcomputer, and outputs an instruction signal of making the drive circuit perform transmission/reception processing of the ultrasonic wave. Further, the control circuit performs a variety of types of processing based on the reception signals input from the reception circuit of the drive circuit. For example, when using the ultrasonic apparatus  100  as the range sensor, the control circuit calculates the distance from the ultrasonic device  10  to the object based on the time from the transmission timing of the ultrasonic wave to the reception timing of the reception signal. 
     Wall Width and Wall Length of Wall  22  in Ultrasonic Device  10   
     Then, the wall width and the wall length of the wall  22  of the ultrasonic device  10  will be described based on  FIG. 2 . 
     It should be noted that in the following description, the wall  22  located between the opening parts  21  adjacent to each other in the transmission channel CH O , namely the wall  22  located between the ultrasonic transmitters  11  adjacent to each other, is referred to as an inter-transmission wall  22   O . The wall  22  located between the opening parts  21  adjacent to each other in the reception channel CH I , namely the wall  22  located between the ultrasonic receivers  12  adjacent to each other, is referred to as an inter-reception wall  22   I . The wall  22  disposed between the opening part  21  which is disposed in the transmission channel CH O  adjacent to the reception channel CH I , and is disposed closest to the reception channel CH I , and the opening part  21  which is adjacent to that opening part  21 , and is disposed in the reception channel CH I , namely the wall  22  located between the ultrasonic transmitter  11  and the ultrasonic receiver  12  adjacent to each other, is referred to as a transmission-reception wall  22   IO . The ultrasonic transmitter  11  which is disposed in the transmission channel CH O  adjacent to the reception channel CH I , and is disposed closest to the reception channel CH I  is referred to as an outermost ultrasonic transmitter  11 A. 
     Further, the wall width of the wall  22  means the dimension of the wall  22  along the arrangement direction of the two opening parts  21  sandwiching the wall  22 , namely the distance between the two opening parts  21  sandwiching the wall  22 . Further, the wall length of the wall  22  means the length of the wall  22  from an end part on the vibrating plate  30  side to an end part at the opposite side to the vibrating plate  30 , namely the dimension in the Z direction of the wall  22 , and the thickness of the substrate  20 . 
     Further, in the present embodiment, the width of a part of the protruding part  52  to be bonded to the vibrating plate  30  is smaller than the width of the wall  22 . The width of the part of the protruding part  52  to be bonded to the vibrating plate  30  means the dimension of the protruding part  52  along the arrangement direction of the two vibrating sections  31  sandwiching the protruding part  52 . 
     In the example shown in  FIG. 2 , the plurality of opening parts  21  lines along the Y direction, and in these opening parts  21 , the opening part  21  which is located in the transmission channel CH O , and is closest to the reception channel CH I  corresponds to a first opening part  211  in the present disclosure, the opening part  21  which is located in the reception channel CH I , and is adjacent to the first opening part in the X direction corresponds to a second opening part  212  in the present disclosure, and the transmission-reception wall  22   IO  located between the first opening part and the second opening part corresponds to a first wall in the present disclosure. Further, the opening part  21  which is located in the transmission channel CH O , and is adjacent to the first opening part  211  corresponds to a third opening part  213  in the present disclosure, and the inter-transmission wall  22   O  located between the first opening part  211  and the third opening part  213  corresponds to a second wall in the present disclosure. Further, each of the vibrating sections  31  disposed at positions overlapping the first opening parts  211  in a plan view viewed from the Z direction corresponds to a first vibrating section  311  in the present disclosure, and the outermost ultrasonic transmitters  11 A including these first vibrating sections  311  each correspond to a first ultrasonic transmitter  111  in the present disclosure. Each of the vibrating sections  31  disposed at positions overlapping the second opening parts  212  in the plan view viewed from the Z direction corresponds to a second vibrating section  312  in the present disclosure. Each of the vibrating sections  31  disposed at positions overlapping the third opening parts  213  in the plan view viewed from the Z direction corresponds to a third vibrating section  313  in the present disclosure, and the ultrasonic transmitters  11  including the third vibrating sections  313  each correspond to a second ultrasonic transmitter  112  in the present disclosure. 
     Further, in the present embodiment, the wall width W IO  of the transmission-reception wall  22   IO  is made different in dimension from the wall width of the inter-transmission wall  22   O . As described above, when the wall width W O  of the inter-transmission wall  22   O  and the wall width W IO  of the transmission-reception wall  22   IO  are different from each other, when driving the ultrasonic transmitters  11  of the transmission channel CH O , the crosstalk generated in that transmission channel CH O  is reflected by the transmission-reception wall  22   IO . Therefore, it is possible to suppress the influence of the crosstalk from the transmission channel CH O  to the reception channel CH I . 
     Further, the outermost ultrasonic transmitter  11 A is the ultrasonic transmitter  11  the closest to the reception channel CH I  of those in the transmission channel CH O , and is the ultrasonic transmitter  11  which exerts the most significant influence of the crosstalk to the reception channel CH I . The outermost ultrasonic transmitter  11 A is formed by being surrounded by the transmission-reception wall  22   IO  and the inter-transmission wall  220 . In this case, the crosstalk component from the outermost ultrasonic transmitter  11 A to other ultrasonic transmitters  11  and the ultrasonic receivers  12  changes in accordance with the wall width W IO  of the transmission-reception wall section  22   IO  and the wall width W O  of the inter-transmission wall  22   O . In other words, when the crosstalk component from the outermost ultrasonic transmitter  11 A to the ultrasonic transmitter  11  increases, the crosstalk component from the outermost ultrasonic transmitter  11 A to the ultrasonic receiver  12  decreases accordingly. 
       FIG. 4  is a diagram showing a relationship between the wall width of the wall  22  surrounding the ultrasonic transmitter  11  and the crosstalk ratio. It should be noted that  FIG. 4  shows the crosstalk ratio when fixing the wall length at 90 μm, and changing the wall width. Further,  FIG. 5  is a diagram showing the relationship between the wall width of the wall  22  and the crosstalk ratio with respect to each of the cases of setting the wall length of the wall  22  surrounding the ultrasonic transmitter to 50 μm, 70 μm, and 90 μm, respectively. Further, the crosstalk ratio described here is a value representing the amplitude of the crosstalk when varying the wall width in a range from 10 μm to 100 μm assuming the amplitude of the crosstalk when setting the wall width to 100 μm, and the wall length to 90 μm as a reference value “1.” 
     As shown in  FIG. 4 , the crosstalk ratio decreases as the wall width increases. In this case, taking the point at which the wall width is 40 μm as a changing point, when the wall width is smaller than 40 μm, the change in the crosstalk ratio is rapid. In contrast, when the wall width becomes longer than 40 μm, the crosstalk ratio decreases, but the change rate is low, and the change is gentle as shown in  FIG. 4 . 
     Further,  FIG. 5  is a single logarithmic chart setting the axis representing the wall width of the wall  22  as a logarithmic axis, and when the wall length is 90 μm, the crosstalk ratio substantially linearly changes with respect to the change in the wall width. This shows the fact that the threshold value of the influence of the wall length on the crosstalk ratio is 90 μm. In other words, the crosstalk ratio when the wall length is no smaller than 90 μm becomes substantially the same as when the wall length is 90 μm. It should be noted that in  FIG. 5 , the crosstalk ratio with respect to the wall width when the wall length is no smaller than 90 μm is omitted from the illustration taking the eye-friendliness into consideration. 
     As shown in  FIG. 5 , by setting the wall length no larger than 90 μm, it is possible to reduce the crosstalk ratio. Incidentally, the crosstalk ratio is reduced only when the wall width is no smaller than 40 μm, and when the wall width is smaller than 40 μm, the difference in crosstalk ratio is extremely small even when setting the wall length no larger than 90 μm. 
     As is understood from  FIG. 4 , when making the wall width W IO  of the transmission-reception wall  22   IO  larger than the wall width W O  of the inter-transmission wall  22   O , the crosstalk ratio from the outermost ultrasonic transmitter  11 A to the ultrasonic receiver  12  of the reception channel CH I  becomes lower than the crosstalk ratio from the outermost ultrasonic transmitter  11 A to the ultrasonic transmitter  11  adjacent to the outermost ultrasonic transmitter  11 A in the transmission channel CH O . In other words, the crosstalk from the outermost ultrasonic transmitter  11 A to the ultrasonic receiver  12  of the reception channel CH I  is reduced. 
     Further, the wall width W IO  of the transmission-reception wall  22   IO  is preferably no smaller than 40 μm. Thus, the crosstalk from the outermost ultrasonic transmitter  11 A to the ultrasonic receiver  12  of the reception channel CH I  can more effectively be reduced. In contrast, when the wall width W IO  of the transmission-reception wall  22   IO  exceeds 90 μm, there is a possibility that the growth in planar size of the ultrasonic device  10  is incurred, and depending on the transmission angle of the ultrasonic wave transmitted from the transmission channel CH O , the reception sensitivity when receiving the ultrasonic wave reflected by the object with the reception channel CH I  reduces. Therefore, it is more preferable to make the wall width W IO  of the transmission-reception wall  22   IO  no smaller than 40 μm and no larger than 90 μm. 
     Moreover, as shown in  FIG. 5 , it is preferable to make the wall length of the transmission-reception wall  22   IO  no larger than 90 μm. On the other hand, when making the wall length smaller than 30 μm, the mechanical strength of the inter-transmission wall  22   O  reduces. Therefore, it is more preferable to make the wall length of the inter-transmission wall  22   O  no smaller than 30 μm and no larger than 90 μm. 
     In contrast, it is preferable to make the wall width W O  of the inter-transmission wall  22   O  smaller than 40 μm. Thus, it is possible to increase the crosstalk component from the outermost ultrasonic transmitter  11 A to the ultrasonic transmitter  11  adjacent to the outermost ultrasonic transmitter  11 A in the transmission channel CH O . Therefore, the crosstalk from the outermost ultrasonic transmitter  11 A to the ultrasonic receiver  12  of the reception channel CH I  can more effectively be reduced. On the other hand, when making the wall width W O  of the inter-transmission wall  22   O  smaller than 30 μm, the mechanical strength of the inter-transmission wall  22   O  reduces. Therefore, it is more preferable to make the wall width W O  of the inter-transmission wall  22   O  no smaller than 30 μm and smaller than 40 μm. 
     Further, it is preferable to form the inter-transmission walls  220  and the transmission-reception walls  22   IO  by providing the opening parts  21  to the substrate  20  as a parallel plate with etching or the like taking the manufacturing process into consideration. Therefore, the wall length of the inter-transmission wall  220  becomes the same in dimension as the wall length of the transmission-reception wall  22   IO . Here, when making the wall width W O  of the inter-transmission wall  22   O  smaller than 40 μm, the influence of the crosstalk ratio by the wall length is extremely small as shown in  FIG. 5 . Therefore, even when the wall length of the inter-transmission wall  22   O  is small, there is no chance for the crosstalk component from the outermost ultrasonic transmitter  11 A toward the reception channel CH I  to increase. 
     It should be noted that it is preferable to make the wall width W I  of the inter-reception wall  22   1  the same in dimension as the wall width W O  of the inter-transmission wall  22   O . Further, it is preferable to make the wall  22  between the transmission channels CH O  adjacent to each other the same in dimension as the wall width W IO . In this case, it is possible to commonalize the opening parts  21  between the three channels lining in the X direction. 
     Protruding Part Wall Width and Protruding Part Wall Length of Protruding Part  52  in Ultrasonic Device  10   
     As described above, in the present embodiment, the edges on the ±Y sides of the vibrating section  31  are defined by edges of the walls  22  constituting the opening part  21 . On the other hand, the edges on the ±X sides of the vibrating section  31  are defined by edges of the protruding parts  52  of the protective member  50 . 
     In the following description, the protruding part  52  disposed between the ultrasonic transmitters  11  is referred to as an inter-transmission protruding part  520 , the protruding part  52  disposed between the ultrasonic receivers  12  is referred to as an inter-reception protruding part  521 , and the protruding part  52  disposed between the outermost ultrasonic transmitter  11 A and the ultrasonic receiver  12  is referred to as a transmission-reception protruding part  52   IO . 
     Further, the protruding part wall width means the dimension of the protruding part  52  along the arrangement direction of the vibrating sections  31  disposed so as to sandwich the protruding part  52 , namely the distance between the two vibrating sections  31  sandwiching the protruding part  52 . Further, the protruding dimension of the protruding part  52  from the base part  51  to the vibrating plate  30 , namely the groove depth of the recessed part  53 , is referred to as the protruding part wall length. 
     In the example shown in  FIG. 3 , the plurality of vibrating sections  31  lines in the X direction across the protruding part  52 , and in these vibrating sections  31 , the vibrating section  31  which is located in the transmission channel CH O , and is closest to the reception channel CH I  corresponds to a fourth vibrating section  314  in the present disclosure, the vibrating section  31  which is located in the reception channel CH I , and is adjacent to the fourth vibrating section  314  in the X direction corresponds to a fifth vibrating section  315  in the present disclosure, and the transmission-reception protruding part  52   IO  located between the fourth vibrating section  314  and the fifth vibrating section  315  corresponds to a first protruding part in the present disclosure. Further, another vibrating section  31  which is located in the transmission channel CH O , and is adjacent to the fourth vibrating section  314  corresponds to a sixth vibrating section  316  in the present disclosure, and the inter-transmission protruding part  52   O  located between the fourth vibrating section  314  and the sixth vibrating section  316  corresponds to a second protruding part in the present disclosure. Further, the outermost ultrasonic transmitter  11 A including the fourth vibrating section  314  corresponds to a third ultrasonic transmitter  113  in the present disclosure. The fifth vibrating section  315  and the piezoelectric element  40  disposed in the fifth vibrating section  315  constitute one ultrasonic receiver  12 . The ultrasonic transmitter  11  including the sixth vibrating section  316  corresponds to a fourth ultrasonic transmitter  114  in the present disclosure. 
     Further, in the present embodiment, the protruding part wall width U IO  of the transmission-reception protruding part  52   IO  is made different in dimension from the protruding part wall width U O  of the inter-transmission protruding part  520 . As described above, when the protruding part wall width U O  of the inter-transmission protruding part  520  and the protruding part wall width U IO  of the transmission-reception protruding part  52   IO  are different from each other, when driving the ultrasonic transmitters  11  of the transmission channel CH O , the crosstalk generated in that transmission channel CH O  is reflected by the transmission-reception protruding part  52   IO . Therefore, it is possible to suppress the influence of the crosstalk from the transmission channel CH O  to the reception channel CH I . 
       FIG. 6  is a diagram showing a relationship between the protruding part wall width and the crosstalk ratio. It should be noted that in  FIG. 6 , the protruding part wall length is fixed at 90 μm. Further,  FIG. 7  is a diagram showing the relationship between the protruding part wall width and the crosstalk ratio with respect to each of the cases of setting the protruding part wall length of the protruding part  52  to 50 μm, 70 μm, and 90 μm, respectively. Further, the crosstalk ratio described in the present embodiment is a value representing the amplitude of the crosstalk when varying the protruding part wall width in a range from 10 μm to 100 μm assuming the amplitude of the crosstalk when setting the protruding part wall width to 100 μm, and the protruding part wall length to 90 μm as a reference value “1.” 
     As shown in  FIG. 6 , the relationship between the protruding part wall width and the crosstalk ratio is substantially the same as the relationship between the wall width and the crosstalk ratio, and the crosstalk ratio decreases as the protruding part wall width increases. More specifically, taking the point at which the wall width is 40 μm as a changing point, when the protruding part wall width is smaller than 40 μm, the change in the crosstalk ratio is rapid. In contrast, when the protruding part wall width is no smaller than 40 μm, the change in the crosstalk ratio is gentle with respect to the change in the protruding part wall width. 
     Further, as shown in  FIG. 7 , in the single logarithmic chart setting the axis representing the protruding part wall width of the protruding part  52  as a logarithmic axis, the crosstalk ratio changes substantially linearly with respect to the change in wall width when the protruding part wall length is 90 μm similarly to the relationship between the wall width and the crosstalk ratio shown in  FIG. 5 . This shows the fact that the threshold value of the influence of the protruding part wall length on the crosstalk ratio is 90 μm. In other words, the crosstalk ratio when the protruding part wall length is no smaller than 90 μm becomes substantially the same as when the protruding part wall length is 90 μm. 
     As shown in  FIG. 7 , by setting the wall length no larger than 90 μm, it is possible to further reduce the crosstalk ratio. Incidentally, the crosstalk ratio is reduced only when the protruding part wall width is no smaller than 40 μm, and when the protruding part wall width is smaller than 40 μm, the difference in crosstalk ratio is extremely small even when setting the protruding part wall length no larger than 90 μm. 
     As is understood from  FIG. 6 , when making the protruding part wall width U IO  of the transmission-reception protruding part  52   IO  larger than the protruding part wall width U O  of the inter-transmission protruding part  52   O , the crosstalk ratio from the outermost ultrasonic transmitter  11 A to the ultrasonic receiver  12  of the reception channel CH I  becomes lower than the crosstalk ratio from the outermost ultrasonic transmitter  11 A to the ultrasonic transmitter  11  adjacent to the outermost ultrasonic transmitter  11 A in the transmission channel CH O . In other words, the crosstalk from the outermost ultrasonic transmitter  11 A to the ultrasonic receiver  12  of the reception channel CH I  is reduced. 
     Further, the protruding part wall width U IO  of the transmission-reception protruding part  52   IO  is preferably no smaller than 40 μm. Thus, the crosstalk from the outermost ultrasonic transmitter  11 A to the ultrasonic receiver  12  of the reception channel CH I  can more effectively be reduced. In contrast, when the protruding part wall width U IO  of the transmission-reception protruding part  52   IO  exceeds 90 μm, there is a possibility that the growth in planar size of the ultrasonic device  10  is incurred, and depending on the transmission angle of the ultrasonic wave transmitted from the transmission channel CH O , the reception sensitivity when receiving the ultrasonic wave reflected by the object with the reception channel CH I  reduces. Therefore, it is more preferable to make the protruding part wall width U IO  of the transmission-reception protruding part  52   IO  no smaller than 40 μm and no larger than 90 μm. 
     Moreover, as shown in  FIG. 7 , it is preferable to make the protruding part wall length of the transmission-reception protruding part  52   IO  no larger than 90 μm. Incidentally, when making the protruding part wall length smaller than 20 μm, there is a possibility that the protective member  50  makes contact with the piezoelectric element  40  vibrating together with the vibrating section  31 . Therefore, it is more preferable to make the protruding part wall length of the inter-transmission protruding part  520  no smaller than 20 μm and no larger than 90 μm. 
     In contrast, it is preferable to make the protruding part wall width U O  of the inter-transmission protruding part  520  smaller than 40 μm. Thus, it is possible to increase the crosstalk component from the outermost ultrasonic transmitter  11 A to the ultrasonic transmitter  11  adjacent to the outermost ultrasonic transmitter  11 A in the transmission channel CH O . Therefore, the crosstalk from the outermost ultrasonic transmitter  11 A to the ultrasonic receiver  12  of the reception channel CH I  can more effectively be reduced. Incidentally, when making the protruding part wall width U O  of the inter-transmission protruding part  520  smaller than 30 μm, the mechanical strength of the inter-transmission protruding part  52   O  reduces, and at the same time, the bonding strength between the vibrating plate  30  and the protruding part  52  also reduces. Therefore, it is more preferable to make the protruding part wall width U O  of the inter-transmission protruding part  520  no smaller than 30 μm and smaller than 40 μm. 
     Further, in the protective member  50 , it is preferable to provide the recessed parts  53  to a parallel plate, or to bond the protruding parts  52  to the base part  51  as the parallel plate taking the manufacturing process into consideration. In this case, the inter-transmission protruding part  52   O  and the transmission-reception protruding part  52   IO  become the same in dimension as each other. When making the protruding part wall width U O  of the inter-transmission protruding part  520  smaller than 40 μm, the influence of the crosstalk ratio by the protruding part wall length is extremely small as shown in  FIG. 7 . Therefore, even when the protruding part wall length of the inter-transmission protruding part  52   O  is small, there is no chance for the crosstalk component from the outermost ultrasonic transmitter  11 A toward the reception channel CH I  to increase. 
     It should be noted that it is also possible to make the protruding part wall width U I  of the inter-reception protruding part  521  smaller than the protruding part wall width U IO  and the protruding part wall width U O . As shown in  FIG. 1 , when disposing the eight transmission channels CH O  so as to surround the ±X sides and the ±Y sides of the reception channel CH I , the distance between the transmission channels CH O  becomes the protruding part wall width U O . In this case, since the protruding part wall width U IO  of the transmission-reception protruding part  52   IO  becomes larger than the protruding part wall width U O , the protruding part wall width U I  of the inter-reception protruding part  52   I  is made smaller than the protruding part wall width U O , accordingly. Thus, it is possible to optimize the arrangement of the ultrasonic transmitters  11  and the ultrasonic receiver  12  in the ultrasonic device  10 . 
     Functions and Advantages of Present Embodiment 
     The ultrasonic device  10  of the ultrasonic apparatus  100  according to the present embodiment is provided with the substrate  20  provided with the plurality of opening parts  21  and the walls  22  each disposed between the opening parts  21  adjacent to each other, the vibrating plate  30  closing the opening parts  21 , and the piezoelectric elements  40  (the vibrators) disposed on the vibrating plate  30  at the positions overlapping the opening parts  21  in the plan view viewed from the Z direction. The plurality of opening parts  21  includes the first opening part  211 , the second opening part  212  adjacent to the first opening part  211  via the transmission-reception wall  22   IO  (the first wall), and the third opening part  213  adjacent to the first opening part  211  via the inter-transmission wall  22   O  (the second wall). The first vibrating section  311  closing the first opening part  211  of the vibrating plate  30  and the piezoelectric element  40  disposed in the first vibrating section  311  constitute the first ultrasonic transmitter  111  (the outermost ultrasonic transmitter  11 A) for transmitting the ultrasonic wave. The second vibrating section  312  closing the second opening part  212  of the vibrating plate  30  and the piezoelectric element  40  disposed in the second vibrating section  312  constitute the ultrasonic receiver  12  for receiving the ultrasonic wave. The third vibrating section  313  closing the third opening part  213  of the vibrating plate  30  and the piezoelectric element  40  disposed in the third vibrating section  313  constitute the second ultrasonic transmitter  112  for transmitting the ultrasonic wave. Further, in the present embodiment, the wall width W IO  of the transmission-reception wall  22   IO  is larger than the wall width W O  of the inter-transmission wall  22   O . 
     In such a present embodiment, since the wall width W O  of the inter-transmission wall  22   O  and the wall width W IO  of the transmission-reception wall  22   IO  are different from each other, due to the principle of antiresonance, the crosstalk from the transmission channel CH O  toward the reception channel CH I  is reflected by the transmission-reception wall  22   IO . Further, since the wall width W IO  is larger than the wall width W O , the crosstalk component from the outermost ultrasonic transmitter  11 A to the reception channel CH I  becomes smaller than the crosstalk component from the outermost ultrasonic transmitter  11 A to the transmission channel CH O . Thus, it is possible to suppress the crosstalk from the transmission channel CH O  to the reception channel CH I . Further, in the present embodiment, since there is no need to provide a concave groove or the like to the substrate  20 , strength reduction of the substrate  20  does not occur, and the configuration of the ultrasonic device  10  is not complicated as well. In other words, in the present embodiment, it is possible to suppress the crosstalk while preventing the strength reduction of the substrate  20  with the simple configuration. 
     In the ultrasonic device  10  according to the present embodiment, the wall width W IO  of the transmission-reception wall  22   IO  is no smaller than 40 μm, and the wall width W O  of the inter-transmission wall  22   O  is smaller than 40 μm. 
     As shown in  FIG. 3 , taking the point at which the wall width is 40 μm as a change point, when the wall width is no smaller than 40 μm, the crosstalk ratio is stably maintained to a low value no higher than 10. In contrast, when the wall width is lower than 40 μm, the smaller the wall width becomes, the higher the crosstalk ratio becomes, and at the same time, the change in crosstalk becomes rapid. Therefore, by making the wall width W IO  no smaller than 40 μm, the crosstalk component from the outermost ultrasonic transmitter  11 A toward the reception channel CH I  decreases, and by making the wall width W O  smaller than 40 μm, the crosstalk component from the outermost ultrasonic transmitter  11 A toward another ultrasonic transmitter  11  in the transmission channel CH O  increases. Thus, it is possible to further reduce the crosstalk from the transmission channel CH O  to the reception channel CH I . 
     In the ultrasonic device  10  according to the present embodiment, the wall length of the walls  22  including the inter-transmission wall  22   O , the transmission-reception wall  22   IO , and the inter-reception wall  22   1  is no larger than 90 μm. 
     By making the wall length of the transmission-reception wall  22   IO  no larger than 90 μm, it is possible to reduce the crosstalk ratio, and it is possible to further suppress the crosstalk from the ultrasonic transmitter  11  in the transmission channel CH O  to the reception channel CH I . Further, when the wall width of the wall  22  is smaller than 40 μm, the change in the crosstalk ratio due to the difference in wall length is extremely small. Therefore, there is no chance that the crosstalk component between the ultrasonic transmitters  11  decreases by making the wall width W O  of the inter-transmission wall  22   O  smaller than 40 μm. In other words, the crosstalk component from the outermost ultrasonic transmitter  11 A toward the reception channel CH I  is reduced, and the crosstalk component toward another ultrasonic transmitter  11  in the transmission channel CH O  is increased, and thus, it is possible to further reduce the crosstalk from the transmission channel CH O  to the reception channel CH I . 
     The ultrasonic device  10  according to the present embodiment is provided with the vibrating plate  30 , the protective member  50  provided with the protruding parts  52  which is bonded to the vibrating plate  30  to divide the vibrating plate  30  into the plurality of vibrating sections  31 , and the piezoelectric elements  40  (the vibrators) disposed in the respective vibrating sections  31 . The plurality of vibrating sections  31  includes the fourth vibrating section  314 , the fifth vibrating section  315  adjacent to the fourth vibrating section  314  via the transmission-reception protruding part  52   IO  (the first projecting part), and the sixth vibrating section  316  adjacent to the fourth vibrating section  314  via the inter-transmission protruding part  520  (the second protruding part). The fourth vibrating section  314  and the piezoelectric element  40  disposed in the fourth vibrating section  314  constitute the third ultrasonic transmitter  113  as the outermost ultrasonic transmitter  11 A. The fifth vibrating section  315  and the piezoelectric element  40  disposed in the fifth vibrating section  315  constitute the ultrasonic receiver  12 . The sixth vibrating section  316  and the piezoelectric element  40  disposed in the sixth vibrating section  316  constitute the fourth ultrasonic transmitter  114 . Further, the protruding part wall width U IO  of the transmission-reception protruding part  52   IO  is larger than the protruding part wall width U O  of the inter-transmission protruding part  52   O . 
     In such a present embodiment, since the protruding part wall width U O  of the inter-transmission protruding part  520  and the protruding part wall width U IO  of the transmission-reception protruding part  52   IO  are different from each other, due to the principle of antiresonance, the crosstalk from the transmission channel CH O  to the reception channel CH I  is reflected by the transmission-reception protruding part  52   IO . Further, since the protruding part wall width U IO  is larger than the protruding part wall width U O , the crosstalk component from the outermost ultrasonic transmitter  11 A to the reception channel CH I  becomes smaller than the crosstalk component from the outermost ultrasonic transmitter  11 A to the transmission channel CH O . Thus, it is possible to suppress the crosstalk from the transmission channel CH O  to the reception channel CH I . Further, in the present embodiment, since there is no need to provide a concave groove or the like to the substrate  20 , strength reduction of the substrate  20  does not occur, and the configuration of the ultrasonic device is not complicated as well. Therefore, it is possible to suppress the crosstalk while preventing the strength reduction of the substrate  20  with the simple configuration. 
     In the ultrasonic device  10  according to the present embodiment, the protruding part wall width U IO  of the transmission-reception protruding part  52   IO  is no smaller than 40 μm, and the protruding part wall width U O  of the inter-transmission protruding part  520  is smaller than 40 μm. 
     As shown in  FIG. 6 , taking the point at which the wall width is 40 μm as a change point, when the protruding part wall width is no smaller than 40 μm, the crosstalk ratio is stably maintained to a low value no higher than 10. In contrast, when the protruding part wall width is lower than 40 μm, the smaller the wall width becomes, the more rapidly the crosstalk ratio increases. Therefore, by making the protruding part wall width U IO  no smaller than 40 μm, it is possible to reduce the crosstalk component from the outermost ultrasonic transmitter  11 A toward the reception channel CH I , and by making the protruding part wall width U O  smaller than 40 μm, it is possible to increase the crosstalk component from the outermost ultrasonic transmitter  11 A toward another ultrasonic transmitter  11  in the transmission channel CH O . Thus, it is possible to further reduce the crosstalk from the transmission channel CH O  to the reception channel CH I . 
     In the ultrasonic device  10  according to the present embodiment, the wall length of the protruding parts  52  including the inter-transmission protruding part  52   O , the transmission-reception protruding part  52   IO , and the inter-reception protruding part  521  is no larger than 90 μm. 
     By making the protruding part wall length of the transmission-reception protruding part  52   IO  no larger than 90 μm, it is possible to reduce the crosstalk ratio, and it is possible to further suppress the crosstalk from the ultrasonic transmitter  11  in the transmission channel CH O  to the reception channel CH I . Further, when the protruding part wall width of the protruding part  52  is smaller than 40 μm, the change in the crosstalk ratio due to the difference in the projection part wall length is extremely small. Therefore, there is no chance that the crosstalk component between the ultrasonic transmitters  11  decreases by making the projecting part wall width U O  of the inter-transmission protruding part  52   O  smaller than 40 μm. In other words, the crosstalk component from the outermost ultrasonic transmitter  11 A to the reception channel CH I  is reduced, and the crosstalk component to another ultrasonic transmitter  11  in the transmission channel CH O  is increased, and thus, it is possible to further reduce the crosstalk from the transmission channel CH O  to the reception channel CH I . 
     MODIFIED EXAMPLES 
     It should be noted that the present disclosure is not limited to each of the embodiments described above, but includes modifications and improvements within a range where the advantages of the present disclosure can be achieved, and configurations, which can be obtained by, for example, arbitrarily combining the embodiments. 
     Modified Example 1 
     For example, in the embodiment described above, it is assumed that the vibrating section  31  is the area surrounded by the edges of the opening parts  21  elongated in the X direction, and the edges of the protruding parts  52  elongated in the Y direction out of the vibrating plate  30 . In contrast, it is possible to adopt a configuration in which the substrate is provided with a plurality of opening parts corresponding respectively to the vibrating sections  31 , and a configuration in which the opening parts are arranged in the X direction and the Y direction to form a two-dimensional array structure. In this case, the outer shape of the vibrating section  31  is defined by only the edges (the edges of the wall) of the opening part. 
     When adopting such a configuration, it is sufficient to form each of the opening parts so that the wall width W IO  of the transmission-reception wall  22   IO  becomes larger than the wall width W O  of the inter-transmission wall  22   O  not only in the Y direction but also in the X direction. In this case, it is not required to provide the protective member  50  with the protruding parts  52 . 
     Further, it is also possible to adopt a configuration in which the protective member  50  is provided with a plurality of recessed parts opposed to the respective vibrating sections  31 , and a configuration in which the outer shape of each of the vibrating sections  31  is defined by only the edges of the recessed part. In this case, there is adopted a configuration in which the recessed parts are arranged in the X direction and the Y direction to form a two-dimensional array structure. 
     When adopting such a configuration, it is sufficient to form each of the recessed parts so that the protruding part wall width U IO  of the transmission-reception projecting part  52   IO  becomes larger than the protruding part wall width U O  of the inter-transmission protruding part  520  not only in the X direction but also in the Y direction. In this case, it is not required to provide the substrate  20 . 
     Further, it is also possible to adopt a configuration in which the substrate is provided with a plurality of opening parts corresponding respectively to the vibrating sections  31 , and at the same time, the protective member is provided with a plurality of recessed parts corresponding respectively to the vibrating sections  31 . In this case, it is also possible to make the protruding part wall width of the protruding part  52  the same in dimension as the wall width of the wall  22 . 
     Specifically, there is adopted a configuration in which the wall width W IO  of the transmission-reception wall  22   IO  and the protruding part wall width U IO  of the transmission-reception protruding part  52   IO  are made the same in dimension as each other, the wall width W O  of the inter-transmission wall  22   O  and the protruding part wall width U O  of the inter-transmission protruding part  52   O  are made the same in dimension as each other, and the wall width W IO  and the protruding part wall width U IO  become larger than the wall width W O  and the protruding part wall width U O . In this case, it is preferable to make the wall length of the wall  22  and the protruding part wall length of the protruding part  52  also the same in dimension as each other. 
     Modified Example 2 
     Although in the embodiment described above, there is described the example in which the wall length of the wall  22  is made no larger than 90 μm, and the protruding part wall length of the protruding part  52  is made no larger than 90 μm, this example is not a limitation. 
     For example, the wall length of the wall  22  can be made larger than 90 μm, and the protruding part wall length of the protruding part  52  can be made larger than 90 μm. 
     In this case, even when the value of the wall length of the wall  22  or the protruding part wall length of the protruding part  52  varies in some degree due to a manufacturing error of the ultrasonic device  10 , the crosstalk ratio does not vary. Therefore, it is possible to provide the ultrasonic device  10  in which there is no chance for the influence of the crosstalk from the transmission channel CH O  to the reception channel CH I  to vary due to the manufacturing error, which adopts the robust design, and which has the stable transmission/reception performance. 
     Further, it is also possible to make the wall length and the protruding part wall length different in accordance with the positions of the wall  22  and the protruding part  52 . 
     For example, it is possible for the transmission-reception wall  22   IO  to be smaller in wall length compared to the inter-transmission wall  22   O . Similarly, it is possible for the transmission-reception protruding part  52   IO  to be smaller in protruding part wall length compared to the inter-transmission protruding part  520 . 
     Modified Example 3 
     In the embodiment described above, there is described the example in which the wall width W IO  of the transmission-reception wall  22   IO  is made no smaller than 40 μm and no larger than 90 μm, and the wall width W O  of the inter-transmission wall  22   O  is made no smaller than 30 μm and smaller than 40 μm. Further, there is described the example in which the protruding part wall width U IO  of the transmission-reception protruding part  52   IO  is made no smaller than 40 μm and no larger than 90 μm, and the protruding part wall width U O  of the inter-transmission protruding part  520  is made no smaller than 30 μm and smaller than 40 μm. In contrast, the wall width W IO , the wall width W O , the protruding part wall width U IO , and the protruding part wall width U O  are not limited to the above. 
     For example, it is also possible for the wall width W IO  to be smaller than 40 μm as long as the wall width W IO  of the transmission-reception wall  22   IO  is larger than the wall width W O  of the inter-transmission wall  22   O . Further, it is also possible for the wall width W O  to be no smaller than 40 μm as long as the wall width W IO  of the transmission-reception wall  22   IO  is larger than the wall width W O  of the inter-transmission wall  220 . It should be noted that as shown in  FIG. 4 , when the wall width is no smaller than 40 μm, the crosstalk ratio with respect to the wall width becomes low in change rate. Therefore, when making the wall width W O  and the wall width W IO  no smaller than 40 μm, it is preferable to, for example, decrease the wall length to thereby reduce the crosstalk component to the reception channel CH I . 
     Further, for example, when adopting a configuration capable of controlling the transmission direction of the ultrasonic wave transmitted form the transmission channel CH O , and so on, it is possible for the wall width W IO  to be no smaller than 90 μm. Further, when the strength of the inter-transmission wall  22   O  is sufficiently high due to the modification of the material of the substrate  20  or the like, it is possible to make the wall width W O  smaller than 30 μm. 
     It should be noted that the same applies to the protruding part wall width U IO  of the protruding part  52  and the protruding part wall width U O . 
     Modified Example 4 
     In the embodiment described above, the piezoelectric element  40  is illustrated as the vibrator, but this is not a limitation. 
     For example, as the vibrator, it is possible to adopt a configuration of provided with a first electrode provided to the vibrating section, and a second electrode fixed to the first electrode via a gap. In this case, by applying a periodic drive voltage between the first electrode and the second electrode, an electrostatic attractive force acting between the first electrode and the second electrode varies periodically to vibrate the vibrating section, and thus, it is possible to transmit the ultrasonic wave in accordance with the vibration of the vibrating section from the transmission channel. Further, since the vibrating section vibrates when the ultrasonic wave is received by the reception channel, by detecting a variation in capacitance between the first electrode and the second electrode, it is possible to detect the reception of the ultrasonic wave. 
     CONCLUSION OF PRESENT DISCLOSURE 
     An ultrasonic device according to a first aspect of the present disclosure includes a substrate having a plurality of opening parts, and a wall disposed between the opening parts adjacent to each other, a vibrating plate configured to close the opening parts, and vibrators provided to the vibrating plate at positions overlapping the opening parts when viewed from a stacking direction of the substrate and the vibrating plate, wherein the plurality of opening parts includes a first opening part, a second opening part adjacent to the first opening part via a first wall, and a third opening part adjacent to the first opening part via a second wall, a first vibrating section configured to close the first opening part in the vibrating plate and the vibrator disposed in the first vibrating section constitute a first ultrasonic transmitter configured to transmit an ultrasonic wave, a second vibrating section configured to close the second opening part in the vibrating plate and the vibrator disposed in the second vibrating section constitute an ultrasonic receiver configured to receive an ultrasonic wave, a third vibrating section configured to close the third opening part in the vibrating plate and the vibrator disposed in the third vibrating section constitute a second ultrasonic transmitter configured to transmit an ultrasonic wave, and a width of the first wall from the first opening part to the second opening part is larger than a width of the second wall from the first opening part to the third opening part. 
     In the present aspect, since the wall width of the first wall and the wall width of the second wall are different from each other, due to the principle of antiresonance, the crosstalk component from the first ultrasonic transmitter toward the ultrasonic receiver is reflected by the first wall. Further, since the wall width of the first wall is larger than the wall width of the second wall, the crosstalk component from the first ultrasonic transmitter to the ultrasonic receiver becomes smaller than the crosstalk component from the first ultrasonic transmitter to the second ultrasonic transmitter. Thus, it is possible to suppress the crosstalk from the first ultrasonic transmitter to the ultrasonic receiver. Further, in the present aspect, since there is no need to provide a concave groove or the like to the substrate, the strength reduction of the substrate does not occur, and the configuration of the ultrasonic device is not complicated as well. In other words, in the present aspect, it is possible to suppress the crosstalk while preventing the strength reduction of the substrate with the simple configuration. 
     In the ultrasonic device according to the first aspect, the width of the first wall from the first opening part to the second opening part may be no smaller than 40 μm, and the width of the second wall from the first opening part to the third opening part may be smaller than 40 μm. 
     When transmitting the ultrasonic wave from the ultrasonic transmitter, in the relationship between the wall width of the wall surrounding the ultrasonic transmitter and the crosstalk from the ultrasonic transmitter to another ultrasonic transmitter or the ultrasonic receiver, the amplitude of the crosstalk decreases as the wall width increases. On this occasion, taking the point at which the wall width of the wall is 40 μm as a change point, when the wall width is no smaller than 40 μm, the amplitude of the crosstalk decreases as the wall width increases, but the reduction amount is small. In contrast, when the wall width is lower than 40 μm, the smaller the wall width becomes, the higher the amplitude of the crosstalk becomes, and at the same time, the change in the amplitude becomes rapid. Therefore, by making the wall width of the first wall no smaller than 40 μm, it is possible to reduce the crosstalk component from the first ultrasonic transmitter toward the ultrasonic receiver, and by making the wall width of the second wall smaller than 40 μm, it is possible to increase the crosstalk component from the first ultrasonic transmitter toward the second ultrasonic transmitter. Thus, it is possible to further reduce the crosstalk from the first ultrasonic transmitter to the ultrasonic receiver. 
     In the ultrasonic device according to the first aspect, a dimension of the wall from the vibrating plate to an end surface at an opposite side to the vibrating plate may be no larger than 90 μm. 
     In the present aspect, the wall length, which is the dimension from an end surface on the vibrating plate side of the wall to an end surface at the opposite side to the vibrating plate of the wall, is no larger than 90 μm. When the wall width becomes no smaller than 40 μm, by making the wall length no larger than 90 μm, the smaller the wall length becomes, the more the crosstalk is reduced. Therefore, by making the wall length of the first wall no larger than 90 μm, it is possible to reduce the crosstalk from the first ultrasonic transmitter to the ultrasonic receiver. 
     Further, when the wall width is smaller than 40 μm, the change in the crosstalk ratio due to the difference in wall length is extremely small. Therefore, when making the wall width of the second wall smaller than 40 μm, the crosstalk component from the first ultrasonic transmitter to the ultrasonic receiver is reduced, and the crosstalk component from the first ultrasonic transmitter to the second ultrasonic transmitter is increased. Therefore, it is possible to further reduce the crosstalk from the first ultrasonic transmitter to the ultrasonic receiver. 
     An ultrasonic device according to a second aspect of the present disclosure includes a vibrating plate, a protective member having a protruding part bonded to the vibrating plate and configured to divide the vibrating plate into a plurality of vibrating sections, and vibrators disposed in the respective vibrating sections of the vibrating plate, wherein the plurality of vibrating sections includes a fourth vibrating section, a fifth vibrating section adjacent to the fourth vibrating section via a first protruding part, and a sixth vibrating section adjacent to the fourth vibrating section via a second protruding part, the fourth vibrating section and the vibrator disposed in the fourth vibrating section constitute a third ultrasonic transmitter configured to transmit an ultrasonic wave, the fifth vibrating section and the vibrator disposed in the fifth vibrating section constitute an ultrasonic receiver configured to receive an ultrasonic wave, the sixth vibrating section and the vibrator disposed in the sixth vibrating section constitute a fourth ultrasonic transmitter configured to transmit an ultrasonic wave, and a width of the first protruding part from the fourth vibrating section to the fifth vibrating section is larger than a width of the second protruding part from the fourth vibrating section to the sixth vibrating section. 
     In the present aspect, since the width (the protruding part wall width) of the first protruding part from the fourth vibrating section to the fifth vibrating section, and the protruding part wall width of the second protruding part are different from each other, due to the principle of antiresonance, the crosstalk component from the third ultrasonic transmitter toward the ultrasonic receiver is reflected by the first wall. Further, since the protruding part wall width of the first protruding part is larger than the protruding part wall width of the second protruding part, the crosstalk component from the third ultrasonic transmitter to the ultrasonic receiver becomes smaller than the crosstalk component from the third ultrasonic transmitter to the fourth ultrasonic transmitter. Thus, it is possible to suppress the crosstalk from the third ultrasonic transmitter to the ultrasonic receiver. Further, in the present aspect, since there is no need to provide a concave groove or the like to the substrate, the strength reduction of the substrate does not occur, and the configuration of the ultrasonic device is not complicated as well. In other words, in the present aspect, similarly to the first aspect, it is possible to suppress the crosstalk while preventing the strength reduction of the substrate with the simple configuration. 
     In the ultrasonic device according to the second aspect, the width of the first protruding part from the fourth vibrating section to the fifth vibrating section may be no smaller than 40 μm, and the width of the second protruding part from the fourth vibrating section to the sixth vibrating section may be smaller than 40 μm. 
     When transmitting the ultrasonic wave from the ultrasonic transmitter, in the relationship between the protruding part wall width of the protruding part surrounding the ultrasonic transmitter and the crosstalk from the ultrasonic transmitter to another ultrasonic transmitter or the ultrasonic receiver, the amplitude of the crosstalk decreases as the protruding part wall width increases. On this occasion, taking the point at which the protruding part wall width is 40 μm as a change point, when the protruding part wall width is no smaller than 40 μm, the amplitude of the crosstalk decreases as the protruding part wall width increases, but the reduction amount is small. In contrast, when the protruding part wall width is lower than 40 μm, the smaller the protruding part wall width becomes, the higher the amplitude of the crosstalk becomes, and at the same time, the change in the amplitude becomes rapid. Therefore, by making the protruding part wall width of the first protruding part no smaller than 40 μm, it is possible to reduce the crosstalk component from the third ultrasonic transmitter toward the ultrasonic receiver, and by making the protruding part wall width of the second protruding part smaller than 40 μm, it is possible to increase the crosstalk component from the third ultrasonic transmitter toward the fourth ultrasonic transmitter. Thus, it is possible to further reduce the crosstalk from the third ultrasonic transmitter to the ultrasonic receiver. 
     In the ultrasonic device according to the second aspect, the protective member may include a base part opposed to the vibrating plate, the protruding part may be disposed so as to protrude from the base part toward the vibrating plate, and a dimension of the protruding part from the vibrating plate to the base part may be no larger than 90 μm. 
     In the present aspect, the protruding part wall length as the dimension of the protruding part from the vibrating plate to the base part is no larger than 90 μm. When the protruding part wall width becomes no smaller than 40 μm, by making the protruding part wall length no larger than 90 μm, the smaller the wall length becomes, the more the crosstalk is reduced. Therefore, by making the protruding part wall length of the first protruding part no larger than 90 μm, it is possible to reduce the crosstalk from the third ultrasonic transmitter to the ultrasonic receiver. 
     Further, when the protruding part wall width is smaller than 40 μm, the change in the crosstalk ratio due to the difference in protruding part wall length is extremely small. Therefore, when making the protruding part wall width of the second protruding part smaller than 40 μm, irrespective of the protruding part wall length, the crosstalk component from the third ultrasonic transmitter to the ultrasonic receiver is reduced, and the crosstalk component from the third ultrasonic transmitter to the fourth ultrasonic transmitter is increased. From the reason described hereinabove, it is possible to further reduce the crosstalk from the third ultrasonic transmitter to the ultrasonic receiver.