Patent Publication Number: US-2020294692-A1

Title: Cable and ultrasonic device

Description:
The present application is based on, and claims priority from JP Application Serial Number 2019-043909, filed Mar. 11, 2019, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a cable and an ultrasonic device. 
     2. Related Art 
     JP-A-2014-241209 discloses a cable having a plurality of inner cables and a braided shield provided at an outer circumference of the inner cables and formed of wires braided together. 
     In the cable of JP-A-2014-241209, the braided shield covers the inner cables and thus provides a shielding effect in which the influence of an external noise is reduced. 
     However, for example, when the cable described in JP-A-2014-241209 is bent, the wires forming the braided shield may be broken, posing the risk of reducing the shielding effect. 
     SUMMARY 
     A cable according to a first application example of the present disclosure includes a core line. The core line includes a signal line transmitting a signal, a ground line having a ground potential, and a shield line covering the signal line and the ground line. The ground line and the shield line are electrically coupled together. 
     In the cable according to the application example, the shield line may be formed of a plurality of wires formed of a conductor and braided together. 
     In the cable according to the application example, the shield line may be formed of a wire formed of a conductor and helically wrapped. 
     In the cable according to the application example, the shield line may include a signal shield line covering the signal line, and a ground shield line covering the ground line. The signal shield line and the ground shield line may be electrically coupled to the ground line. 
     In the cable according to the application example, the signal line may include a transmission signal line transmitting a drive signal between a first piezoelectric element transmitting an ultrasonic wave and a transmitting circuit controlling transmission of an ultrasonic wave, and a reception signal line transmitting a reception signal between a second piezoelectric element receiving an ultrasonic wave and a receiving circuit controlling reception of an ultrasonic wave. The signal shield line may include a transmission shield line covering the transmission signal line, and a reception shield line covering the reception signal line. The transmission shield line and the reception shield line may be electrically coupled to the ground line. 
     In the cable according to the application example, the ground line may include a first ground line and a second ground line. The transmission shield line may be electrically coupled to the first ground line. The reception shield line may be electrically coupled to the second ground line. 
     In the cable according to the application example, the ground line may include a first ground line and a second ground line. The transmission shield line and the reception shield line may be electrically coupled to the first ground line and the second ground line. 
     In the cable according to the application example, the ground line and the shield line may be electrically coupled together at both ends. 
     An ultrasonic device according to a second application example includes: the cable according to the first application example; an ultrasonic sensor coupled to one end of the cable; and a control unit coupled to the other end of the cable and controlling the ultrasonic sensor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing a schematic configuration of an ultrasonic device according to a first embodiment. 
         FIG. 2  is a partly broken perspective view showing essential parts at an end of the cable according to the first embodiment. 
         FIG. 3  is a partly broken perspective view showing essential parts at an end of a cable according to a second embodiment. 
         FIG. 4  is a partly broken perspective view showing essential parts at an end of a cable according to a third embodiment. 
         FIG. 5  is a partly broken perspective view showing essential parts at an end of a cable according to a fourth embodiment. 
         FIG. 6  is a block diagram showing essential parts of an ultrasonic device according to a modification example. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     First Embodiment 
     An ultrasonic device  100  according to a first embodiment of the present disclosure will now be described with reference to the drawings. 
     Schematic Configuration of Ultrasonic Device  100   
       FIG. 1  is a block diagram showing a schematic configuration of the ultrasonic device  100  according to this embodiment. 
     As shown in  FIG. 1 , the ultrasonic device  100  has a cable  1 , an ultrasonic sensor  2 , and a control device  3 . 
     The ultrasonic device  100  according to this embodiment transmits an ultrasonic wave to a target object from the ultrasonic sensor  2  and receives the ultrasonic wave reflected off the target object. The ultrasonic device  100  is configured as a distance measuring device calculating the distance from the ultrasonic sensor  2  to the target object, based on the time from the timing of transmitting the ultrasonic wave to the timing of receiving the ultrasonic wave. 
     Ultrasonic Sensor  2   
     The ultrasonic sensor  2  has a probe casing  21 , a transmitting element  22 , and a receiving element  23 . 
     The probe casing  21  accommodates the transmitting element  22  and the receiving element  23 . The probe casing  21  is provided with a sensor window  211  at a position corresponding to the transmitting element  22  and the receiving element  23 . 
     The probe casing  21  is also provided with a passage hole  212 . The cable  1  is inserted in the probe casing  21  via the passage hole  212 . Thus, the ultrasonic sensor  2  is coupled to one end of the cable  1 . 
     The probe casing  21  is also provided with a probe frame ground  213  to which an outer circumferential shield line  14  of the cable  1 , described later, is electrically coupled. 
     The transmitting element  22  has a piezoelectric film, not illustrated. The transmitting element  22  is configured to be able to send out an ultrasonic wave as the piezoelectric film vibrates when a drive signal is applied thereto. The transmitting element  22  is an example of the first piezoelectric element according to the present disclosure. 
     A transmission signal line  111  and a ground line  131  of the cable  1 , described later, are electrically coupled to the transmitting element  22 . 
     The receiving element  23  has a piezoelectric film, not illustrated, similarly to the transmitting element  22 . When the piezoelectric film vibrates due to the ultrasonic wave sent out from the transmitting element  22  and reflected off the target object, a potential difference is generated between above and below the piezoelectric film. Thus, the receiving element  23  is configured to be able to output a reception signal corresponding to the ultrasonic wave by detecting the potential difference. The receiving element  23  is an example of the second piezoelectric element according to the present disclosure. 
     A reception signal line  121  and the ground line  131  of the cable  1 , described later, are electrically coupled to the receiving element  23 . 
     Control Device  3   
     The control device  3  has a control device casing  31  and a circuit board  32 . The control device  3  is an example of the control unit according to the present disclosure. 
     The control device casing  31  accommodates the circuit board  32 . The control device casing  31  is provided with a passage hole  311 . The cable  1  is inserted in the control device casing  31  via the passage hole  311 . Thus, the control device  3  is coupled to the other end of the cable  1 . 
     The control device casing  31  is also provided with a control device frame ground  312  to which the outer circumferential shield line  14  of the cable  1 , described later, is electrically coupled. 
     The circuit board  32  has a transmitting circuit  321 , a receiving circuit  322 , and a control circuit  323 . 
     The transmitting circuit  321  is a signal output unit controlled by the control circuit  323  and outputting a drive signal. The transmitting circuit  321  is electrically coupled to the transmitting element  22  via the cable  1 . Thus, the transmitting circuit  321  outputs the drive signal to the transmitting element  22  via the cable  1 . 
     The receiving circuit  322  takes in and processes a reception signal outputted from the receiving element  23  via the cable  1 . Specifically, the receiving circuit  322  includes, for example, a low-noise amplifier circuit, voltage-controlled attenuator, programmable gain amplifier, low-pass filter, A/D converter or the like. The receiving circuit  322  performs various kinds of signal processing such as converting the reception signal to a digital signal, eliminating a noise component, and amplifying the reception signal to a desired signal level, and subsequently outputs the processed reception signal to the control circuit  323 . 
     The control circuit  323  is formed of, for example, a computing circuit such as a CPU, and a storage circuit such as a memory. The control circuit  323  controls the transmitting circuit  321  and the receiving circuit  322 . The control circuit  323  calculates the distance from the ultrasonic sensor  2  to the target object by a ToF (time-of-flight) technique, using the time from when the ultrasonic sensor  2  transmits the ultrasonic wave to when the reception signal is detected, and the speed of sound in the air. 
     Cable  1   
       FIG. 2  is a partly broken perspective view showing essential parts at an end of the able  1 . 
     As shown in  FIGS. 1 and 2 , the cable  1  is a coaxial cable extending between the ultrasonic sensor  2  and the control device  3  and electrically coupling these together. 
     The cable  1  has a transmission signal core line  11 , a reception signal core line  12 , a ground core line  13 , an outer circumferential shield line  14 , an outer cover  15 , and a connector unit  16 . The transmission signal core line  11 , the reception signal core line  12 , and the ground core line  13  form the core line according to the present disclosure. 
     Transmission Signal Core Line  11   
     As shown in  FIG. 2 , the transmission signal core line  11  has a transmission signal line  111 , a transmission shield line  112 , and a transmission shield cover  113 . 
     The transmission signal line  111  electrically couples the transmitting element  22  of the ultrasonic sensor  2  and the transmitting circuit  321  of the control device  3  to each other. Thus, the transmission signal line  111  transmits a drive signal outputted from the transmitting circuit  321  to the transmitting element  22 . The transmission signal line  111  forms the signal line according to the present disclosure. 
     The transmission signal line  111  has a transmission conductor  1111  and a transmission conductor cover  1112 . 
     The transmission conductor  1111  is formed of a copper wire and transmits a drive signal. However, the transmission conductor  1111  is not limited to being formed of a copper wire and may be formed of a conductor of a metal material such as a copper alloy or aluminum. 
     The transmission conductor cover  1112  is formed of a polyethylene member and covers the transmission conductor  1111 . This can prevent a short circuit between the transmission conductor  1111  and the transmission shield line  112 . The transmission conductor cover  1112  is not limited to being formed of a polyethylene member and may be formed of any insulating material. 
     The transmission shield line  112  is formed as a braided shield formed of a plurality of wires  1121  braided together, and covers the transmission signal line  111 . In this embodiment, the wire  1121  is formed of a copper foil thread. The transmission shield line  112  has, at its both ends, a transmission shield lead wire  1122  formed of a plurality of wires  1121  stranded together. 
     The wire  1121  is not limited to being formed of a copper foil thread and may be formed of a conductor of a metal material such as a copper alloy or aluminum. 
     The transmission shield line  112  forms the shield line according to the present disclosure. The transmission shield line  112  also forms the signal shield line according to the present disclosure. 
     The transmission shield cover  113  is formed of a polyethylene member and covers the transmission shield line  112 . This can prevent a short circuit between the transmission shield line  112 , and the reception signal core line  12  and the ground core line  13 . The transmission shield cover  113  is not limited to being formed of a polyethylene member and may be formed of any insulating material. 
     Reception Signal Core Line  12   
     The reception signal core line  12  has a reception signal line  121 , a reception shield line  122 , and a reception shield cover  123 . 
     The reception signal line  121  electrically couples the receiving element  23  of the ultrasonic sensor  2  and the receiving circuit  322  of the control device  3  to each other. Thus, the reception signal line  121  transmits a reception signal outputted from the receiving element  23  to the receiving circuit  322 . The reception signal line  121  forms the signal line according to the present disclosure. 
     The reception signal line  121  has a reception conductor  1211  and a reception conductor cover  1212 . 
     The reception conductor  1211  is formed of a copper wire and transmits a reception signal. However, the reception conductor  1211  is not limited to being formed of a copper wire and may be formed of a conductor of a metal material such as a copper alloy or aluminum. 
     The reception conductor cover  1212  is formed of a polyethylene member and covers the circumference of the reception conductor  1211 . This can prevent a short circuit between the reception conductor  1211  and the reception shield line  122 . The reception conductor cover  1212  is not limited to being formed of a polyethylene member and may be formed of any insulating material. 
     The reception shield line  122  is formed as a braided shield formed of a plurality of wires  1221  braided together, and covers the reception signal line  121 . In this embodiment, the wire  1221  is formed of a copper foil thread. The reception shield line  122  has, at its both ends, a reception shield lead wire  1222  formed of a plurality of wires  1221  stranded together. 
     The wire  1221  is not limited to being formed of a copper foil thread and may be formed of a conductor of a metal material such as a copper alloy or aluminum. 
     The reception shield line  122  forms the shield line according to the present disclosure. The reception shield line  122  also forms the signal shield line according to the present disclosure. 
     The reception shield cover  123  is formed of a polyethylene member and covers the reception shield line  122 . This can prevent a short circuit between the reception shield line  122 , and the transmission signal core line  11  and the ground core line  13 . The reception shield cover  123  is not limited to being formed of a polyethylene member and may be formed of any insulating material. 
     Ground Core Line  13   
     The ground core line  13  has a ground line  131 , aground shield line  132 , and a ground shield cover  133 . 
     The ground line  131  electrically couples a ground terminal of the transmitting element  22  of the ultrasonic sensor  2  and a ground terminal of the transmitting circuit  321  of the control device  3  to each other. Thus, the ground terminal of the transmitting element  22  has the same ground potential as the transmitting circuit  321 . 
     The ground line  131  also electrically couples a ground terminal of the receiving element  23  of the ultrasonic sensor  2  and a ground terminal of the receiving circuit  322  of the control device  3  to each other. Thus, the ground terminal of the receiving element  23  has the same ground potential as the receiving circuit  322 . 
     The ground line  131  has a ground conductor  1311  and a ground conductor cover  1312  and bifurcates at its both ends. 
     The ground conductor  1311  is formed of a copper wire and has a ground potential. However, the ground conductor  1311  is not limited to being formed of a copper wire and may be formed of a conductor of a metal material such as a copper alloy or aluminum. 
     The ground conductor cover  1312  is formed of a polyethylene member and covers the ground conductor  1311 . This can prevent a short circuit between the ground conductor  1311  and the ground shield line  132 . The ground conductor cover  1312  is not limited to being formed of a polyethylene member and may be formed of any insulating material. 
     The ground shield line  132  is formed as a braided shield formed of a plurality of wires  1321  braided together, and covers the ground line  131 . In this embodiment, the wire  1321  is formed of a copper foil thread. The ground shield line  132  has, at its both ends, a ground shield lead wire  1322  formed of a plurality of wires  1321  stranded together. 
     The wire  1321  is not limited to being formed of a copper foil thread and may be formed of a conductor of a metal material such as a copper alloy or aluminum. 
     The ground shield line  132  forms the shield line according to the present disclosure. 
     The ground shield cover  133  is formed of a polyethylene member and covers the ground shield line  132 . This can prevent a short circuit between the ground shield line  132 , and the transmission signal core line  11  and the reception signal core line  12 . The ground shield cover  133  is not limited to being formed of a polyethylene member and may be formed of any insulating material. 
     The transmission signal core line  11 , the reception signal core line  12 , and the ground core line  13  form the core line according to the present disclosure. 
     Outer Circumferential Shield Line  14   
     The outer circumferential shield line  14  is formed as a braided shield formed of a plurality of wires  141  braided together, and covers the transmission signal core line  11 , the reception signal core line  12 , and the ground core line  13 . In this embodiment, the wire  141  is formed of a copper foil thread. The outer circumferential shield line  14  has, at its both ends, an outer circumferential shield lead wire  142 . In this embodiment, the outer circumferential shield lead wire  142  is coupled to the outer circumferential shield line  14  by a solder part  51 . 
     The outer circumferential shield lead wire  142  coupled to the end on the side of the ultrasonic sensor  2  is electrically coupled to the probe frame ground  213  of the probe casing  21  via the connector unit  16 . The outer circumferential shield lead wire  142  coupled to the end on the side of the control device  3  is electrically coupled to the control device frame ground  312  of the control device casing  31  via the connector unit  16 . 
     Outer Cover  15   
     The outer cover  15  is formed of a polyethylene member and covers the outer circumferential shield line  14 . This can prevent a short circuit between the outer circumferential shield line  14  and another external wiring and can also prevent damage to the outer circumferential shield line  14 . The outer cover  15  is not limited to being formed of a polyethylene member and may be formed of an insulating material having weather resistance, wear resistance, and the like. 
     Connector Unit  16   
     The connector unit  16  is a coupling member provided at both ends of the cable  1  and electrically coupling the ultrasonic sensor  2  and the control device  3  to each other. Specifically, the connector unit  16  provided at one end of the cable  1  is configured to be able to be coupled to a connector, not illustrated, provided in the ultrasonic sensor  2 . The connector unit  16  provided at the other end of the cable  1  is configured to be able to be coupled to a connector, not illustrated, provided in the control device  3 . 
       FIG. 2  shows only the connector unit  16  provided at the one end of the cable  1 , that is, coupled to the connector of the ultrasonic sensor  2 . The connector unit  16  provided at the other end of the cable  1 , that is, coupled to the connector of the control device  3 , is similar to the connector unit  16  shown in  FIG. 2  and therefore will not be described. 
     The connector unit  16  has a connector housing  161  and a connector crimp terminal  162 . The connector housing  161  is formed of a polyamide resin and configured to be able to engage with a housing of the connector, not illustrated, of the ultrasonic sensor  2 . The connector housing  161  accommodates the connector crimp terminal  162 . The connector housing  161  is not limited to being formed of a polyamide resin and may be formed of, for example, a phenol resin. 
     The connector crimp terminal  162  is formed of an oxygen-free copper tube and has a transmitting terminal  1621 , a first common ground terminal  1622 , a second common ground terminal  1623 , a frame ground terminal  1624 , and a receiving terminal  1625 . Terminals corresponding to these terminals  1621  to  1625  are provided in the connector, not illustrated, provided in the ultrasonic sensor  2 . 
     To the transmitting terminal  1621 , the transmission conductor  1111  of the transmission signal line  111  is coupled. Thus, the transmission signal line  111  is electrically coupled to the transmitting element  22  via the transmitting terminal  1621 . 
     To the first common ground terminal  1622 , one of the bifurcated parts of the ground conductor  1311  is coupled. Thus, the ground line  131  is electrically coupled to the transmitting element  22  via the first common ground terminal  1622 . 
     To the second common ground terminal  1623 , the other one of the bifurcated parts of the ground conductor  1311  is coupled. Thus, the ground line  131  is electrically coupled to the receiving element  23  via the second common ground terminal  1623 . 
     To the frame ground terminal  1624 , the outer circumferential shield lead wire  142  of the outer circumferential shield line  14  is coupled. Thus, the outer circumferential shield line  14  is electrically coupled to the probe frame ground  213  via the frame ground terminal  1624 . 
     To the receiving terminal  1625 , the reception conductor  1211  of the reception signal line  121  is coupled. Thus, the reception signal line  121  is electrically coupled to the receiving element  23  via the receiving terminal  1625 . 
     The shielding effect of the outer circumferential shield line  14  drops at the part where the outer circumferential shield lead wire  142  is pulled around. Therefore, a shielded connector having the connector crimp terminal  162  surrounded by a metal may be used as the connector unit  16 . 
     Coupling between Ground Line  131  and Respective Shield Lines  112 ,  122 ,  132   
     The coupling between the ground line  131  and the respective shield lines  112 ,  122 ,  132  will now be described. 
     As shown in  FIG. 2 , at the one end of the cable  1 , the ground conductor  1311  of the ground line  131  and the transmission shield lead wire  1122  of the transmission shield line  112  are coupled together by a solder part  52 . Also, the ground conductor  1311  and the reception shield lead wire  1222  of the reception shield line  122  are coupled together by the solder part  52 . Moreover, the ground conductor  1311  and the ground shield lead wire  1322  of the ground shield line  132  are coupled together by the solder part  52 . That is, the transmission shield lead wire  1122 , the reception shield lead wire  1222 , and the ground shield lead wire  1322 , and the ground conductor  1311  are coupled together by the solder part  52 . Thus, the transmission shield line  112 , the reception shield line  122 , and the ground shield line  132  are electrically coupled to the ground line  131 . 
     At the other end of the cable  1 , the transmission shield line  112 , the reception shield line  122 , and the ground shield line  132  are electrically coupled to the ground line  131 , similarly to the above. 
     Thus, the transmission shield line  112 , the reception shield line  122 , the ground shield line  132  and the ground line  131  are electrically coupled together at both ends. 
     Advantageous Effects of First Embodiment 
     The first embodiment as described above can achieve the following effects. 
     In this embodiment, the ultrasonic device  100  has the cable  1 , the ultrasonic sensor  2 , and the control device  3 . 
     The transmission shield line  112 , the reception shield line  122 , the ground shield line  132 , and the ground line  131  of the cable  1  are electrically coupled together at both ends. 
     Thus, for example, even when the wires  1121 ,  1221 ,  1321  are broken as the cable  1  is bent, the respective shield lines  112 ,  122 ,  132  can release a noise such as an electromagnetic wave via the ground line  131 . Therefore, the shielding effect can be maintained even when the wires  1121 ,  1221 ,  1321  are broken. 
     In this embodiment, each of the shield lines  112 ,  122 ,  132  is formed as a braided shield formed of a plurality of wires  1121 ,  1221 ,  1321  formed of conductive copper foil threads and braided together. 
     Thus, since the braided shield is very flexible, the wires  1121 ,  1221 ,  1321  can be made less likely to be broken when the cable  1  is bent. Therefore, a reduction in the shielding effect can be restrained in the respective shield lines  112 ,  122 ,  132 . 
     In this embodiment, the cable  1  has the transmission signal line  111  transmitting a drive signal between the transmitting element  22  and the transmitting circuit  321 , and the reception signal line  121  transmitting a reception signal between the receiving element  23  and the receiving circuit  322 . 
     Thus, in the ultrasonic device  100 , the influence of a noise such as an electromagnetic wave on the drive signal and the reception signal can be restrained. 
     Second Embodiment 
     A second embodiment of the present disclosure will now be described with reference to  FIG. 3 . The second embodiment is different from the first embodiment in that a transmission signal line  111 A and a first ground line  134 A are formed as a twisted pair cable. The second embodiment is also different from the first embodiment in that a reception signal line  121 A and a second ground line  135 A are formed as a twisted pair cable. 
     In the second embodiment, a component identical or similar to that in the first embodiment is denoted by the same reference sign and its description is omitted or simplified. 
       FIG. 3  is a partly broken cross-sectional view showing essential parts at an end of a cable  1 A according to the second embodiment. 
     As shown in  FIG. 3 , the cable  1 A has a transmission signal core line  11 A and a reception signal core line  12 A. 
     Transmission Signal Core Line  11 A 
     The transmission signal core line  11 A has a transmission signal line  111 A, a first ground line  134 A, a transmission shield line  112 A, and a transmission shield cover  113 . 
     The transmission signal core line  11 A transmits a drive signal outputted from the transmitting circuit  321  to the transmitting element  22 , as in the first embodiment. 
     The transmission signal line  111 A has a transmission conductor  1111 A and a transmission conductor cover  1112 A. In this embodiment, the transmission conductor  1111 A and the transmission conductor cover  1112 A are formed similarly to the transmission conductor  1111  and the transmission conductor cover  1112  in the first embodiment. 
     The first ground line  134 A electrically couples the ground terminal of the transmitting element  22  of the ultrasonic sensor  2  and the ground terminal of the transmitting circuit  321  of the control device  3  to each other. Thus, the ground terminal of the transmitting element  22  has the same ground potential as the ground terminal of the transmitting circuit  321 . 
     The first ground line  134 A has a first ground conductor  1341 A and a first ground conductor cover  1342 A. In this embodiment, the first ground conductor  1341 A and the first ground conductor cover  1342 A are formed similarly to the ground conductor  1311  and the ground conductor cover  1312  in the first embodiment. 
     In this embodiment, the transmission signal line  111 A and the first ground line  134 A are stranded together and formed as a twisted pair cable. 
     The transmission shield line  112 A is formed as a braided shield formed of a plurality of wires  1121 A braided together, as in the first embodiment. 
     In this embodiment, the transmission shield line  112 A covers the transmission signal line  111 A and the first ground line  134 A stranded together. 
     The transmission shield line  112 A has, at its both ends, a transmission shield lead wire  1122 A formed of a plurality of wires  1121 A stranded together. The transmission shield lead wire  1122 A is coupled to the first ground line  134 A. Thus, the transmission shield line  112 A and the first ground line  134 A are electrically coupled together at both ends. 
     Reception Signal Core Line  12 A 
     The reception signal core line  12 A has a reception signal line  121 A, a second ground line  135 A, a reception shield line  122 A, and a reception shield cover  123 . 
     The reception signal line  121 A outputs a reception signal outputted from the receiving element  23  to the receiving circuit  322 , as in the first embodiment. 
     The reception signal line  121 A has a reception conductor  1211 A and a reception conductor cover  1212 A. In this embodiment, the reception conductor  1211 A and the reception conductor cover  1212 A are formed similarly to the reception conductor  1211  and the reception conductor cover  1212  in the first embodiment. 
     The second ground line  135 A electrically couples the ground terminal of the receiving element  23  of the ultrasonic sensor  2  and the ground terminal of the receiving circuit  322  of the control device  3  to each other. Thus, the ground terminal of the receiving element  23  has the same ground potential as the ground terminal of the receiving circuit  322 . 
     The second ground line  135 A has a second ground conductor  1351 A and a second ground conductor cover  1352 A. In this embodiment, the second ground conductor  1351 A and the second ground conductor cover  1352 A are formed similarly to the ground conductor  1311  and the ground conductor cover  1312  in the first embodiment. 
     In this embodiment, the reception signal line  121 A and the second ground line  135 A are stranded together and formed as a twisted pair cable. 
     The reception shield line  122 A is formed as a braided shield formed of a plurality of wires  1221 A braided together, as in the first embodiment. 
     In this embodiment, the reception shield line  122 A covers the reception signal line  121 A and the second ground line  135 A stranded together. 
     The reception shield line  122 A has, at its both ends, a reception shield lead wire  1222 A formed of a plurality of wires  1221 A stranded together. The reception shield lead wire  1222 A is coupled to the second ground line  135 A. Thus, the reception shield line  122 A and the second ground line  135 A are electrically coupled together at both ends. 
     Advantageous Effects of Second Embodiment 
     The second embodiment as described above can achieve the following effects. 
     In this embodiment, the transmission shield line  112 A and the first ground line  134 A are electrically coupled together. 
     Thus, even when the wire  1121 A is broken, the transmission shield line  112 A can release a noise such as an electromagnetic wave via the first ground line  134 A. Therefore, the shielding effect can be maintained even when the wire  1121 A is broken. 
     The transmission signal line  111 A and the first ground line  134 A are stranded together and formed as a twisted pair cable. 
     Therefore, the influence of a noise such as an electromagnetic wave on the drive signal transmitted through the transmission signal line  111 A can be restrained. 
     In this embodiment, the reception shield line  122 A and the second ground line  135 A are electrically coupled together. 
     Thus, even when the wire  1221 A is broken, the reception shield line  122 A can release a noise such as an electromagnetic wave via the second ground line  135 A. Therefore, the shielding effect can be maintained even when the wire  1221 A is broken. 
     The reception signal line  121 A and the second ground line  135 A are stranded together and formed as a twisted pair cable. 
     Therefore, the influence of a noise such as an electromagnetic wave on the reception signal transmitted through the reception signal line  121 A can be restrained. 
     Third Embodiment 
     A third embodiment of the present disclosure will now be described with reference to  FIG. 4 . The third embodiment is different from the second embodiment in that a transmission shield line  112 B and a reception shield line  122 B are electrically coupled to a first ground line  134 B and a second ground line  135 B. 
     In the third embodiment, a component identical or similar to that in the first and second embodiments is denoted by the same reference sign and its description is omitted or simplified. 
       FIG. 4  is a partly broken cross-sectional view showing essential parts at an end of a cable  1 B according to the third embodiment. 
     As shown in  FIG. 4 , the cable  1 B has a transmission signal core line  11 B and a reception signal core line  12 B. 
     Transmission Signal Core Line  11 B 
     The transmission signal core line  11 B has a transmission signal line  111 B, a first ground line  134 B, a transmission shield line  112 B, and a transmission shield cover  113 . 
     The transmission signal line  111 B has a transmission conductor  1111 B and a transmission conductor cover  1112 B. 
     The first ground line  134 B has a first ground conductor  1341 B and a first ground conductor cover  1342 B. 
     In this embodiment, the transmission signal line  111 B and the first ground line  134 B are stranded together and formed as a twisted pair cable, as in the second embodiment. 
     The transmission shield line  112 B is formed as a braided shield formed of a plurality of wires  1121 B braided together, as in the first and second embodiments. 
     The transmission shield line  112 B has, at its both ends, a transmission shield lead wire  1122 B formed of a plurality of wires  1121 B stranded together. The transmission shield lead wire  1122 B is coupled to the first ground line  134 B, as in the second embodiment. Thus, the transmission shield line  112 B and the first ground line  134 B are electrically coupled together at both ends. 
     Reception Signal Core Line  12 B 
     The reception signal core line  12 B has a reception signal line  121 B, a second ground line  135 B, a reception shield line  122 B, and a reception shield cover  123 . 
     The reception signal line  121 B has a reception conductor  1211 B and a reception conductor cover  1212 B. 
     The second ground line  135 B has a second ground conductor  1351 B and a second ground conductor cover  1352 B. 
     In this embodiment, the reception signal line  121 B and the second ground line  135 B are stranded together and formed as a twisted pair cable, as in the second embodiment. 
     The reception shield line  122 B is formed as a braided shield formed of a plurality of wires  1221 B braided together, as in the first and second embodiments. 
     The reception shield line  122 B has, at its both ends, a reception shield lead wire  1222 B formed of a plurality of wires  1221 B stranded together. The reception shield lead wire  1222 B is coupled to the second ground line  135 B, as in the second embodiment. Thus, the reception shield line  122 B and the second ground line  135 B are electrically coupled together at both ends. 
     In this embodiment, a shield lead wire  17 B is coupled to the transmission shield line  112 B and the reception shield line  122 B. Thus, the transmission shield line  112 B and the reception shield line  122 B are electrically coupled together via the shield lead wire  17 B. That is, the transmission shield line  112 B, the reception shield line  122 B, the first ground line  134 B, and the second ground line  135 B are electrically coupled together at both ends. 
     Advantageous Effects of Third Embodiment 
     The third embodiment as described above can achieve the following effects. 
     In this embodiment, the transmission shield line  112 B and the reception shield line  122 B are electrically coupled to the first ground line  134 B and the second ground line  135 B. 
     Thus, even when the wires  1121 B,  1221 B are broken, the transmission shield line  112 B and the reception shield line  122 B can release a noise such as an electromagnetic wave via the first ground line  134 B and the second ground line  135 B. Therefore, the shielding effect can be maintained more securely. 
     Fourth Embodiment 
     A fourth embodiment of the present disclosure will now be described with reference to  FIG. 5 . The fourth embodiment is different from the first to third embodiments in that a transmission shield line  112 C, a reception shield line  122 C, a ground shield line  132 C, and an outer circumferential shield line  14 C are formed as helically wrapped shields helically wrapped with wires  1121 C,  1221 C,  1321 C,  141 C, respectively. 
     In the fourth embodiment, a component identical or similar to that in the first to third embodiments is denoted by the same reference sign and its description is omitted or simplified. 
       FIG. 5  is a partly broken cross-sectional view showing essential parts at an end of a cable  1 C according to the fourth embodiment. 
     As shown in  FIG. 5 , the cable  1 C has a transmission signal core line  11 C, a reception signal core line  12 C, and a ground core line  13 C. 
     Transmission Signal Core Line  11 C 
     The transmission signal core line  11 C has a transmission signal line  111 C, a transmission shield line  112 C, and a transmission shield cover  113 . 
     The transmission signal line  111 C has a transmission conductor  1111 C and a transmission conductor cover  1112 C. 
     In this embodiment, the transmission shield line  112 C is formed as a helically wrapped shield helically wrapped with a wire  1121 C. The transmission shield line  112 C has, at its both ends, a transmission shield lead wire  1122 C formed as an extension of the wire  1121 C. 
     Reception Signal Core Line  12 C 
     The reception signal core line  12 C has a reception signal line  121 C, a reception shield line  122 C, and a reception shield cover  123 . 
     The reception signal line  121 C has a reception conductor  1211 C and a reception conductor cover  1212 C. 
     In this embodiment, the reception shield line  122 C is formed as a helically wrapped shield helically wrapped with a wire  1221 C. The reception shield line  122 C has, at its both ends, a reception shield lead wire  1222 C formed as an extension of the wire  1221 C. 
     Ground Core Line  13 C 
     The ground core line  13 C has a ground line  131 C, a ground shield line  132 C, and a ground shield cover  133 . 
     The ground line  131 C has a ground conductor  1311 C and a ground conductor over  1312 C. 
     In this embodiment, the ground shield line  132 C is formed as a helically wrapped shield helically wrapped with a wire  1321 C. The ground shield line  132 C has, at its both ends, a ground shield lead wire  1322 C formed as an extension of the wire  1321 C. 
     Outer Circumferential Shield Line  14 C 
     The outer circumferential shield line  14 C covers the transmission signal core line  11 C, the reception signal core line  12 C, and the ground core line  13 C. 
     In this embodiment, the outer circumferential shield line  14 C is formed as a helically wrapped shield helically wrapped with a wire  141 C. The outer circumferential shield line  14 C has, at its both ends, an outer circumferential shield lead wire  142 C formed as an extension of the wire  141 C. 
     In this embodiment, the outer circumferential shield lead wire  142 C is electrically coupled to the probe frame ground  213  of the probe casing  21  and the control device frame ground  312  of the control device casing  31 , as in the first to third embodiments. 
     Coupling between Ground Line  131 C and Respective Shield Lines  112 C,  122 C,  132 C 
     As shown in  FIG. 5 , at the one end of the cable  1 C, the transmission shield lead wire  1122 C, the reception shield lead wire  1222 C, and the ground shield lead wire  1322 C, and the ground conductor  1311 C are coupled together, as in the first embodiment. Thus, the transmission shield line  112 C, the reception shield line  122 C, and the ground shield line  132 C are electrically coupled to the ground line  131 C. 
     At the other end of the cable  1 C, the transmission shield line  112 C, the reception shield line  122 C, and the ground shield line  132 C are electrically coupled to the ground line  131 C, similarly to the above. 
     Thus, the transmission shield line  112 C, the reception shield line  122 C, the ground shield line  132 C, and the ground line  131 C are electrically coupled together at both ends. 
     Advantageous Effects of Fourth Embodiment 
     The fourth embodiment as described above can achieve the following effects. 
     In this embodiment, the transmission shield line  112 C, the reception shield line  122 C, the ground shield line  132 C, and the ground line  131 C are electrically coupled together at both ends. 
     Therefore, even when the wires  1121 C,  1221 C,  1321 C are broken, the shielding effect can be maintained, as in the first embodiment. Also, the transmission shield line  112 C, the reception shield line  122 C, the ground shield line  132 C, and the outer circumferential shield line  14 C are formed as helically wrapped shields helically wrapped with the wires  1121 C,  1221 C,  1321 C,  141 C, respectively, and therefore even more flexible than when formed as braided shields. Thus, the wires  1121 C,  1221 C,  1321 C,  141 C can be made less likely to be broken when the cable  1 C is bent. This can restrain a reduction in the shielding effect. 
     Modification Examples 
     The present disclosure is not limited to the above embodiments and includes modifications, improvements and the like within a range that can achieve the object of the present disclosure. 
     In the embodiments, the connector unit  16  is provided with the first common ground terminal  1622  and the second common ground terminal  1623 . However, this is not limiting. 
       FIG. 6  is a block diagram showing essential parts of an ultrasonic device  100 D according to a modification example. As shown in  FIG. 6 , a connector unit  16 D provided at both ends of a cable  1 D may be provided with only one common ground terminal  1622 D coupled to a ground line of a ground core line  13 D. In this case, the ground line is electrically coupled to the transmitting element  22  and the receiving element  23  via the common ground terminal  1622 D. 
     In the first and fourth embodiment, the transmission shield line  112 ,  112 C, the reception shield line  122 ,  122 C, the ground shield line  132 ,  132 C, and the ground line  131 ,  131 C are electrically coupled together at both ends. However, this is not limiting. For example, the transmission shield line  112 ,  112 C, the reception shield line  122 ,  122 C, the ground shield line  132 ,  132 C, and the ground line  131 ,  131 C may be electrically coupled together at the connector unit  16 . In this case, the transmission shield line  112 ,  112 C, the reception shield line  122 ,  122 C, the ground shield line  132 ,  132 C, and the ground line  131 ,  131 C may be coupled to a common coupling terminal and thus electrically coupled together. 
     In the second embodiment, the transmission shield line  112 A and the first ground line  134 A are electrically coupled together at both ends. However, this is not limiting. For example, the transmission shield line  112 A and the first ground line  134 A may be electrically coupled together at the connector unit  16 . In this case, the transmission shield line  112 A and the first ground line  134 A may be coupled to a common coupling terminal and thus electrically coupled together. 
     Similarly, the reception shield line  122 A and the second ground line  135 A are electrically coupled together at both ends. However, this is not limiting. For example, the reception shield line  122 A and the second ground line  135 A may be electrically coupled together at the connector unit  16 . In this case, the reception shield line  122 A and the second ground line  135 A may be coupled to a common coupling terminal and thus electrically coupled together. 
     In the third embodiment, the transmission shield line  112 B, the reception shield line  122 B, the first ground line  134 B, and the second ground line  135 B are electrically coupled together at both ends. However, this is not limiting. For example, the transmission shield line  112 B, the reception shield line  122 B, the first ground line  134 B, and the second ground line  135 B may be electrically coupled together at the connector unit  16 . In this case, the transmission shield line  112 B, the reception shield line  122 B, the first ground line  134 B, and the second ground line  135 B maybe coupled to a common coupling terminal and thus electrically coupled together. 
     In the first embodiment, the transmission shield line  112 , the reception shield line  122 , the ground shield line  132 , and the outer circumferential shield line  14  are formed as braided shields. However, this is not limiting. For example, the transmission shield line  112 , the reception shield line  122 , and the ground shield line  132  may be formed as helically wrapped shields, and the outer circumferential shield line  14  may be formed as a braided shield. Each of the shield lines  112 ,  122 ,  132 ,  14  may be formed either as a braided shield or as a helically wrapped shield. 
     In the second embodiment, the transmission shield line  112 A, the reception shield line  122 A, and the outer circumferential shield line  14  are formed as braided shields. However, this is not limiting. For example, the transmission shield line  112 A and the reception shield line  122 A may be formed as helically wrapped shields, and the outer circumferential shield line  14  maybe formed as a braided shield. Each of the shield lines  112 A,  122 A,  14  may be formed either as a braided shield or as a helically wrapped shield. 
     In the third embodiment, the transmission shield line  112 B, the reception shield line  122 B, and the outer circumferential shield line  14  are formed as braided shields. However, this is not limiting. For example, the transmission shield line  112 B and the reception shield line  122 B may be formed as helically wrapped shields, and the outer circumferential shield line  14  maybe formed as a braided shield. Each of the shield lines  112 B,  122 B,  14  may be formed either as a braided shield or as a helically wrapped shield. 
     In the embodiments, the transmitting circuit  321  and the receiving circuit  322  are provided at the circuit board  32  in the control device  3 . However, this is not limiting. For example, a circuit board may be provided in the ultrasonic sensor  2 , and a transmitting circuit and a receiving circuit may be provided at this circuit board. 
     In the embodiments, the transmitting element  22  and the receiving element  23  are provided in the ultrasonic sensor  2 . However, this is not limiting. For example, a transmitting/receiving element that can transmit and receive an ultrasonic wave may be provided in the ultrasonic sensor  2 , and the transmitting/receiving element may be configured to be able to switch between transmission and reception of an ultrasonic wave. 
     In the embodiments, the ultrasonic device  100  is formed as a distance measuring device. However, this is not limiting. For example, the ultrasonic device  100  may be applied to an ultrasonic measuring device measuring an interior tomographic image of a structure according to a result of transmission/reception of an ultrasonic wave. 
     In the embodiments, the cable  1 , LA,  1 B,  1 C,  1 D electrically couples the ultrasonic sensor  2  and the control device  3  to each other. However, this is not limiting. The cable may be used as a cable electrically coupling various devices together. 
     Also, a specific structure for embodying the present disclosure may be formed by an appropriate combination of the embodiments and modification examples within a range that can achieve the object of the present disclosure, or may be properly changed to another structure.