Patent Publication Number: US-2011061466-A1

Title: Wireless ultrasonic diagnostic apparatus and ultrasonic probe

Description:
FIELD OF THE INVENTION 
     The present invention relates to a wireless ultrasonic diagnostic apparatus for transmitting and receiving radio signals between an ultrasonic probe and an ultrasonic observation device, and an ultrasonic probe included in this wireless ultrasonic diagnostic apparatus. 
     BACKGROUND OF THE INVENTION 
     Medical diagnoses using an ultrasonic diagnostic apparatus are prevalent. The ultrasonic diagnostic apparatus is composed of an ultrasonic probe and an ultrasonic observation device. At a tip of the ultrasonic probe, ultrasonic transducers (hereinafter referred to as UTs) are arranged. The UTs emit ultrasonic waves to a human body, and receive reflected waves from an object of interest in the human body. Thereby, detection signals are output. The detection signals are electrically processed in the ultrasonic observation device. Thus, an ultrasonic image is obtained. 
     A wireless ultrasonic diagnostic apparatus is known as one of the examples of the ultrasonic diagnostic apparatus. An ultrasonic probe and an ultrasonic observation device of the wireless ultrasonic diagnostic apparatus have wireless communication function (see Japanese Patent Laid-Open Publications No. 53-108690, No. 55-151952, and No. 2002-085405). In the wireless ultrasonic diagnostic apparatus, detection signals are modulated or converted into radio signals in the ultrasonic probe, and then the radio signals are transmitted to the ultrasonic observation device. The radio signals are demodulated or converted back into the detection signals in the ultrasonic observation device, and thus an ultrasonic image is generated based on the detection signals. A cable for connecting the ultrasonic probe and the ultrasonic observation device is unnecessary, which improves operability of the ultrasonic probe significantly. 
     The wireless ultrasonic diagnostic apparatus, on the other hand, may cause communication failure between the ultrasonic probe and the ultrasonic observation device due to a position of an operator or a layout of an examination room. For example, in the case where an ultrasonic observation device is located behind an operator, he or she may block the radio signals transmitted from the ultrasonic probe. As a result, the ultrasonic observation device fails to receive the radio signals. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a wireless ultrasonic diagnostic apparatus capable of carrying out communication between an ultrasonic probe and an ultrasonic observation device in a good condition, and an ultrasonic probe included in this wireless ultrasonic diagnostic apparatus. 
     In order to achieve the above and other objects, the wireless ultrasonic diagnostic apparatus of the present invention includes multiple ultrasonic probes, an ultrasonic observation device used for the ultrasonic diagnosis, a wireless communication section, and a wireless communication controller. The multiple ultrasonic probes include a first ultrasonic probe being used for ultrasonic diagnosis and one or more second ultrasonic probes not being used for the ultrasonic diagnosis. The wireless communication section is provided in each of the ultrasonic probes and the ultrasonic observation device. The wireless communication section wirelessly transmits and receives a radio signal related the ultrasonic diagnosis. The wireless communication controller is provided in each of the ultrasonic probes to control the wireless communication section. The wireless communication controller of the second ultrasonic probe controls its wireless communication section to relay the radio signal such that the radio signal is communicated between the first ultrasonic probe and the ultrasonic observation device via the one or more second ultrasonic probes. 
     It is preferable that each of the ultrasonic probes and the ultrasonic observation device has a routing controller for constructing a route for wireless communication between the first ultrasonic probe and the ultrasonic observation device. 
     It is preferable that each of the ultrasonic probes and the ultrasonic observation device has a received power detector for detecting magnitude of received power of the radio signal received by the wireless communication section. It is preferable that the routing controller constructs the route based on a detection result of the received power detector. 
     It is preferable that each of the ultrasonic probes and the ultrasonic observation device includes a received power detector and an alarm display section. The received power detector detects received power of the radio signals received by the wireless communication section, and the alarm display section gives an alarm when a detection result of the received power detector is lower than a threshold value. 
     It is preferable that each of the ultrasonic probes has a backup section for temporarily storing backup data of the radio signals received by the wireless communication section. 
     It is preferable that the ultrasonic observation device includes a display section for displaying a usage status of the one or more ultrasonic probes. 
     It is preferable that the radio signal transmitted from the first ultrasonic probe to the ultrasonic observation device via the one or more second ultrasonic probes includes identification information of the first and second ultrasonic probes and probe information indicating the usage status of the first and second ultrasonic probes. It is preferable that the ultrasonic observation device includes a display controller for controlling the display section to display the usage status of the first and second ultrasonic probes in a form of a list based on the identification information and the probe information. 
     It is preferable that the usage status includes a diagnosing status in which the ultrasonic probe is being used for the ultrasonic diagnosis, a relaying status in which the ultrasonic probe is being used for relaying the radio signals, and a status in which the ultrasonic probe is available for one of the ultrasonic diagnosis and the relaying. 
     It is preferable each of the ultrasonic probes is provided with an instruction input section for receiving an instruction input signal for operating the ultrasonic probe or the ultrasonic observation device. In the second ultrasonic probe, the wireless communication controller controls the wireless communication section to wirelessly transmit the instruction input signal, received by the instruction input section, to the wireless communication section of the first ultrasonic probe or to the wireless communication section of the ultrasonic observation device. The first ultrasonic probe or the ultrasonic observation device operates according to the received instruction input signal. 
     It is preferable that the wireless ultrasonic diagnostic apparatus further includes a connection section for connecting the second ultrasonic probe in relay and the ultrasonic observation device via wired connection. The wireless communication section of the connected second ultrasonic probe functions as the wireless communication section of the ultrasonic observation device. 
     It is preferable that each of the ultrasonic probes is provided with a relay status indicator to indicate that the wireless communication section is relaying the radio signal. 
     An ultrasonic probe of the present invention includes a wireless communication section and a wireless communication controller. The wireless communication section transmits and receives a radio signal related to ultrasonic diagnosis. The wireless communication controller controls the wireless communication section to relay the radio signal during standby for the ultrasonic diagnosis between other two ultrasonic probes, or between another ultrasonic probe and an ultrasonic observation device used for the ultrasonic diagnosis. 
     In the present invention, the ultrasonic probe not being used for the ultrasonic diagnosis is used to relay radio signals transmitted and received between the ultrasonic probe being used for the ultrasonic diagnosis and the ultrasonic observation device. Accordingly, even if an operator or an obstruction is located between the ultrasonic probe and the ultrasonic observation device, robust wireless communication network is constructed without being affected by the obstruction. As a result, good communication condition can be kept between the ultrasonic probe and the ultrasonic observation device. 
     Conventionally, in the case where an ultrasonic observation device is provided with multiple ultrasonic probes, the ultrasonic probes not being used for the ultrasonic diagnosis are of no use. In the present invention, on the other hand, such ultrasonic probes can be used for relaying the radio signals. 
     The ultrasonic probes and the ultrasonic observation device give an alarm when the detection result of the received power of the radio signal is lower than a predetermined threshold value. As a result, it becomes possible to notify the operator to remove the obstruction between the ultrasonic probe and the ultrasonic observation device or make the ultrasonic probe and the ultrasonic observation device closer to keep the wireless communication in a good condition. 
     The data of the received radio signal is backed up in the ultrasonic probe for relaying the radio signal. As a result, the radio signal is retransmitted when the ultrasonic probe fails to transmit the radio signal. 
     The ultrasonic observation device displays the usage status of the ultrasonic probe. Accordingly, it becomes easy to distinguish the ultrasonic probe according to its usage status. In addition, the usage status is displayed in a form of a list. Thus, the usage status of each ultrasonic probe is checked at a glance. 
     Instead of inputting an operation to the ultrasonic probe being used for ultrasonic diagnosis, the operation can be input to the ultrasonic probe not being used for the diagnosis. As a result, the ultrasonic probe being used for the diagnosis is prevented from being moved due to the input operation during the diagnosis. 
     During the relaying of the radio signals, the ultrasonic probe displays that it is currently used for the relaying. As a result, the ultrasonic probe is prevented from being used for other purposes during the relaying of the radio signals. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects and advantages of the present invention will be more apparent from the following detailed description of the preferred embodiments when read in connection with the accompanied drawings, wherein: 
         FIG. 1  is an external view showing a configuration of a wireless ultrasonic diagnostic apparatus of the first embodiment; 
         FIG. 2  is a block diagram showing an electrical configuration of an ultrasonic probe; 
         FIG. 3  is a block diagram showing an electrical configuration of an ultrasonic observation device; 
         FIG. 4  is an explanatory view showing coverage of a first ultrasonic probe for ultrasonic diagnosis, coverage of a second ultrasonic probe for relaying radio signals, and coverage of an ultrasonic observation device; 
         FIG. 5  is a functional block diagram of a CPU in each of the first and second ultrasonic probes, and the ultrasonic observation device; 
         FIG. 6A  is an explanatory view of route information showing a source, relay points, and a destination of a radio signal; 
         FIG. 6B  is an explanatory view of route request information that requests to construct a route for wireless communication; 
         FIG. 7  is an explanatory view showing how the route information is generated; 
         FIG. 8  is a flowchart showing steps for displaying an ultrasonic image in the wireless ultrasonic diagnostic apparatus of the first embodiment; 
         FIG. 9  is a block diagram showing an electrical configuration of a wireless ultrasonic diagnostic apparatus of the second embodiment; 
         FIG. 10  is a flowchart showing steps for backup processing in the wireless ultrasonic diagnostic apparatus of the second embodiment; 
         FIG. 11  is an explanatory view showing a failure caused in wireless communication between the second ultrasonic probe and the ultrasonic observation device; 
         FIG. 12  is a block diagram showing an electrical configuration of a wireless ultrasonic diagnostic apparatus of the third embodiment; 
         FIG. 13  is a flowchart showing steps for displaying a warning in the wireless ultrasonic diagnostic apparatus of the third embodiment; 
         FIG. 14  is an external view of a wireless ultrasonic diagnostic apparatus of the fourth embodiment; 
         FIG. 15  is a block diagram showing an electrical configuration of the wireless ultrasonic diagnostic apparatus of the fourth embodiment; 
         FIGS. 16A to 16D  are explanatory views showing how the first route information is generated; 
         FIGS. 17A to 17C  are explanatory views showing second to fourth route information; 
         FIG. 18  is a flowchart showing steps for selecting route information in the wireless ultrasonic diagnostic apparatus of the fourth embodiment; 
         FIG. 19  is a block diagram showing an electrical configuration of a wireless ultrasonic diagnostic apparatus of the fifth embodiment; 
         FIG. 20  is a block diagram showing an electrical configuration of a wireless ultrasonic diagnostic apparatus of the sixth embodiment; 
         FIG. 21  is a block diagram showing an electrical configuration of a wireless ultrasonic diagnostic apparatus of the seventh embodiment; and 
         FIG. 22  is a block diagram showing an electrical configuration of a wireless ultrasonic diagnostic apparatus of the eighth embodiment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In  FIG. 1 , a wireless ultrasonic diagnostic apparatus (hereinafter simply referred to as ultrasonic diagnostic apparatus)  10  is composed of an external first ultrasonic probe  11 , an external second ultrasonic probe  12 , and an ultrasonic observation device  13  or imaging device. The first and second ultrasonic probes  11  and  12  have wireless communication function. The ultrasonic diagnostic apparatus  10  is used for a simplified ultrasonic diagnosis at the bedside of a patient. 
     The first and second ultrasonic probes  11  and  12  have the same configuration. The first ultrasonic probe  11  is used for the ultrasonic diagnosis. The second ultrasonic probe  12  is not currently used for the ultrasonic diagnosis, and is held in a predetermined probe holder  15  as an access point position. Hereinafter, a suffix “a” is added to a numeral of a part or member related to the first ultrasonic probe  11 , and a suffix “b” is added to a numeral of a part or member related to the second ultrasonic probe  12 . 
     The first ultrasonic probe  11  is composed of a scan head  16   a , an ultrasonic transducer array (hereinafter abbreviated as UT array)  17   a  incorporated along a tip of the scan head  16   a , a power switch  18   a  and an operation switch  19   a . The power switch  18   a  and the operation switch  19   a  are provided substantially in the middle of the scan head  16   a . The second ultrasonic probe  12  is composed of a scan head  16   b , an ultrasonic transducer array (hereinafter abbreviated as UT array)  17   b  incorporated along a tip of the scan head  16   b , a power switch  18   b , and an operation switch  19   b . The power switch  18   b  and an operation switch  19   b  are provided substantially in the middle of the scan head  16   b . The scan heads  16   a  and  16   b  are held by an operator and placed on a body surface of a patient. 
     The UT arrays  17   a  and  17   b  emit ultrasonic waves to an object of interest inside the body of the patient, and receive the ultrasonic waves or echo reflected from the object of interest. The power switches  18   a  and  18   b  turn on or off the first and second ultrasonic probes  11  and  12 , respectively. 
     The operation switches  19   a  and  19   b  are used for the operations of the first and second ultrasonic probes  11  and  12 , respectively. In addition, the operation switches  19   a  and  19   b  are used for changing or selecting the operation modes and sending various operation orders or instructions to the ultrasonic observation device  13 . The operation modes of the first and second ultrasonic probes  11  and  12  include an observation mode or imaging mode in which ultrasonic waves are transmitted, and a standby mode in which all functions are disabled except for the wireless communication. 
     The ultrasonic observation device  13  is composed of a body  21  and a cover  22 . On a top face of the body  21 , an operating section  23  is disposed. The operating section  23  is provided with multiple buttons and a trackball for inputting various operating instructions to the ultrasonic observation device  13 . Inside the cover  22 , a monitor  24  is provided. The monitor  24  displays ultrasonic images and various operation screens. 
     The cover  22  is attached to the body  21  through a hinge  25 . The cover  22  is rotatable between an open position and a closed position. In the open position, the operating section  23  and the monitor  24  are exposed. In the closed position, the cover  22  covers the top surface of the body  21  to protect the operating section  23  and the monitor  24 . 
     In  FIG. 2 , the UT arrays  17   a  and  17   b  are provided with ultrasonic transducers (hereinafter referred to as UTs)  27   a  and  27   b  spaced uniformly. The UTs  27   a  and  27   b  are composed of piezoelectric elements and oscillate in response to excitation pulses input from drive signal generating circuits  28   a  and  28   b , respectively, to transmit ultrasonic waves to an object of interest. The UTs  27   a  and  27   b  receive the reflected waves from the object of interest, and outputs detection signals to the reception signal processing circuits  29   a  and  29   b , respectively. 
     Under the control of CPUs  30   a  and  30   b , the drive signal generating circuits  28   a  and  28   b  are driven by transmission control circuits  31   a  and  31   b , respectively. Based on orders from the transmission control circuits  31   a  and  31   b , the drive signal generating circuits  28   a  and  28   b  select the UTs  27   a  and  27   b  to which the excitation pulses are input, respectively. The drive signal generating circuits  28   a  and  28   b  sequentially switch or change the UTs  27   a  and  27   b  to be driven at a predetermined time interval, respectively. For example, in the case where there are 128 UTs  27   a  and 128 UTs  27   b , adjacent 48 UTs  27   a  are selected as a block to be driven, and adjacent 48 UTs  27   b  are selected as a block to be driven. Every time a transmission and reception of ultrasonic waves takes place, the next block of the UTs  27   a , one or several UTs  27   a  away from the previous block, and the next block of the UTs  27   b , one or several UTs  27   b  away from the previous block, are driven. 
     Based on orders from the transmission control circuits  31   a  and  31   b , the drive signal generating circuits  28   a  and  28   b  change timings to input excitation pulses to the UTs  27   a  in one block and to the UTs  27   b  in one block, respectively. Thereby, electronic scan is performed in the transmission directions of the ultrasonic waves, or the ultrasonic waves are electronically focused. Each of the transmission control circuits  31   a  and  31   b  generates delay pattern information every time a transmission and reception of ultrasonic waves takes place. The delay pattern information specifies timings to input the excitation pulses to the UTs  27   a  and  27   b.    
     Each UT  27   a  is provided with one reception signal processing circuit  29   a . Each UT  27   b  is provided with one reception signal processing circuit  29   b . In other words, the number of the reception signal processing circuits  29   a  is the same as that of the UTs  27   a , and the number of the reception signal processing circuits  29   b  is the same as that of the UTs  27   b . Under the control of the CPUs  30   a  and  30   b , the reception signal processing circuits  29   a  and  29   b  are driven by reception control circuits  32   a  and  32   b , respectively. 
     Each of the reception signal processing circuits  29   a  and  29   b  is provided with a reception amplifier, and an A/D converter (hereinafter referred to as A/D). The reception amplifiers amplify the detection signals input from the UTs  27   a  and  27   b , respectively. Then, the A/Ds digitally modulate the detection signals. The reception signal processing circuits  29   a  and  29   b  are connected to parallel/serial conversion circuits (hereinafter referred to as P/S conversion circuits  33   a  and  33   b , respectively. 
     The detection signals from the reception signal processing circuits  29   a  and  29   b  are input in parallel to the P/S conversion circuits  33   a  and  33   b , respectively, every time a transmission and reception of ultrasonic waves takes place. In the case where one block is composed of 48 UTs  27   a , and the other block is composed of 48 UTs  27   b , parallel signals of 48 bits are input to each of the P/S conversion circuits  33   a  and  33   b . Under the control of the CPUs  30   a  and  30   b , the P/S conversion circuits  33   a  and  33   b  synchronize clock signals input from synchronization circuits (not shown), respectively, and each of the P/S conversion circuits  33   a  and  33   b  modulates or converts the parallel signals of 48 bits into serial signals. The P/S conversion circuits  33   a  and  33   b  are connected to wireless communication circuits  34   a  and  34   b , respectively. 
     Under the control of the CPU  30   a  and  30   b , the wireless communication circuits  34   a  and  34   b  transmit and receive radio signals to and from other ultrasonic probes and the ultrasonic observation device  13  through antennas  35   a  and  35   b . The wireless communication circuits  34   a  and  34   b  modulate the serial signals input from the P/S conversion circuits  33   a  and  33   b  and various signals input from the CPUs  30   a  and  30   b  into the radio signals. The radio signals are output to the antennas  35   a  and  35   b . The wireless communication circuits  34   a  and  34   b  demodulate or convert the radio signals, received through the antennas  35   a  and  35   b , back into the serial signals or the like. 
     Based on instruction input signals from the operation switches  19   a  and  19   b , the CPUs  30   a  and  30   b  sequentially execute various programs read from ROM areas of memories  36   a  and  36   b  to control overall operations of the first and second ultrasonic probes  11  and  12 , respectively. RAM areas of the memories  36   a  and  36   b  function as working memories for the CPUs  30   a  and  30   b , respectively. The CPUs  30   a  and  30   b  execute processes or temporarily store various data in the RAM areas. 
     In addition, battery control circuits  37   a  and  37   b  are connected the CPUs  30   a  and  30   b , respectively. To the battery control circuits  37   a  and  37   b  are connected the power switches  18   a  and  18   b , batteries  38   a  and  38   b , and power receivers  39   a  and  39   b , respectively. 
     When the power switches  18   a  and  18   b  are turned on, under the control of the CPUs  30   a  and  30   b , the battery control circuits  37   a  and  37   b  control the batteries  38   a  and  38   b  to supply the power to the first and second ultrasonic probes  11  and  12 , respectively. 
     The power receivers  39   a  and  39   b  receive the power supplied by an external charger (not shown). The battery control circuits  37   a  and  37   b  charge the batteries  38   a  and  38   b  with the power supplied via the power receivers  39   a  and  39   b , respectively. 
     As shown in  FIG. 3 , the ultrasonic observation device  13  is provided with a CPU  40 , a memory  41 , a wireless communication circuit  42 , a serial/parallel conversion circuit (hereinafter referred to as S/P conversion circuit)  43 , an image forming circuit  44 , a display control circuit  45 , and the like, in addition to the operating section  23  and the monitor  24 . Based on the instruction input signals from the operating section  23 , the CPU  40  sequentially executes a program read from the memory  41  to control overall operations of the ultrasonic observation device  13 . 
     The wireless communication circuit  42  of the ultrasonic observation device  13  is basically the same as the above described wireless communication circuits  34   a  and  34   b . The wireless communication circuit  42  communicates with the ultrasonic probes  11  and  12  using radio signals through an antenna  47 . The wireless communication circuit  42  demodulates various signals input from the CPU  40  into radio signals, and outputs the radio signals to the antenna  47 . 
     The wireless communication circuit  42  demodulates the radio signals, received through the antenna  47 , into the above-described serial signals, for example. The wireless communication circuit  42  outputs the demodulated serial signals to the S/P conversion circuit  43 , and other demodulated signals to the CPU  40 . 
     The S/P conversion circuit,  43  synchronizes with clock signals input from a phase synchronization circuit (not shown), and demodulates or converts the serial signals back into the parallel signals, that is, one block of the detection signals. The image forming circuit  44  is connected to the S/P conversion circuit  43 . 
     The image forming circuit  44  is provided with a delay-pattern information storage  48 , a phasing and adding section  49 , and an image processor  50 . The delay-pattern information storage  48  stores the above described delay pattern information which wireless communication circuit  42  wirelessly received from the ultrasonic probes  11  and  12 . 
     The phasing and adding section  49  refers to the delay pattern information stored in the delay-pattern information storage  48 , and performs phasing and adding to the detection signals such that the detection signals are in phase with each other. Specifically, the detection signals input from the S/P conversion circuit  43  are sequentially stored on a block-by-block basis, and then the stored detection signals are subjected to phasing and adding when all the detection signals from the UTs  27   a  and  27   b  are stored. 
     The image processor  50  performs various signal processes such as gain correction, log compression, detection, edge enhancement, and filter processing to the detection signals output from the phasing and adding section  49 , and then modulates or converts the detection signals into TV signals. The display control circuit  45  performs D/A conversion to the TV signals output from the image processor  50  to display an ultrasonic image on the monitor  24 . 
     As shown in  FIG. 4 , the probe holder  15  is placed in an area where coverage A 1  of the first ultrasonic probe  11  and coverage A 2  of the ultrasonic observation device  13  overlap with each other. In other words, the first ultrasonic probe  11  and the ultrasonic observation device  13  are located inside coverage A 3  of the second ultrasonic probe  12 . 
     As shown in  FIG. 5 , the CPUs  30   a  and  30   b  read programs from the memories  36   a  and  36   b , and sequentially execute the read programs, respectively. Thereby, the CPU  30   a  of the first ultrasonic probe  11  functions as a routing controller  52   a  and a communication controller  53   a , and the CPU  30   b  of the second ultrasonic probe  12  functions as a routing controller  52   b  and a communication controller  53   b . Likewise, the CPU  40  of the ultrasonic observation device  13  functions as a routing controller  55  and a communication controller  56 . 
     The routing controllers  52   a ,  52   b , and  55  control the wireless communication circuits  34   a ,  34   b , and  42 , respectively, such that the wireless communication circuits located in the same coverage wirelessly communicate with each other. Thereby, route information  58  is generated or constructed. The route information  58  indicates one or more transmission routes of the radio signals between the first ultrasonic probe  11  and the ultrasonic observation device  13 . The wireless communications among the routing controllers  52   a ,  52   b , and  55  are conducted via the wireless communication circuits and the antennas. However, for the sake of simplification, description on the wireless communication circuits and the antennas are omitted. 
     The routing controller  52   a  wirelessly communicates with the routing controller  52   b . The routing controller  52   b  wirelessly communicates with each of the routing controller  52   a  and the routing controller  55 . Accordingly, the routing controller  52   b  relays data transmitted from one of the routing controller  52   a  and the routing controller  55  to the other. 
     Data transmitted from the routing controller  52   a  includes route request information  59  requesting the generation of the route information  58  destined to the ultrasonic observation device  13 . The route request information  59  is transmitted, for example, when the operation mode of the ultrasonic probe  11  is changed to the observation mode, or when the ultrasonic diagnosis using the ultrasonic probe  11  is started. The route request information  59  may be transmitted at a certain time interval. 
     Data transmitted from the routing controller  55  of the ultrasonic observation device  13  includes the route information  58  responding to the route request information  59 . Every time the routing controller  55  receives the route request information  59 , the routing controller  55  transmits the route information  58 , and stores the route information  58  in the memory  41 . The routing controller  52   a  stores the received route information  58  in the memory  36   a . The routing controller  52   b  stores the received route information  58  in the memory  36   b.    
     A communication controller  53   a  of the first ultrasonic probe  11  controls the wireless communication circuit  34   a  to sequentially perform the wireless transmission of the serial signals, output from the P/S conversion circuit  33   a , on the block-by-block basis to the next recipient in the route information  58 . Hereinafter, radio signals into which the serial signals are modulated may be referred to as radio serial signals. 
     The communication controller  53   b  of the second ultrasonic probe  12  controls the wireless communication circuit  34   b  to sequentially relay the radio serial signals received by the wireless communication circuit  34   b  to next recipient stored in the route information  58 . The communication controller  56  of the ultrasonic observation device  13  controls the reception of the radio serial signals by the wireless communication circuit  42 . 
     As shown in  FIG. 6A , the route information  58  is composed of a box  61  for a route request ID and a route table  62 . In the box  61 , the route request ID assigned to the route request information  59  by the routing controller  52   a  is stored. Every time new route request information  59  is issued, the route request ID is incremented by one. In other words, the larger the number of the route request ID, the newer the route information  58  is. 
     The route table  62  indicates one or more transmission routes of the radio signals. The route table  62  is provided with a box  62   a  for source information, a box  62   b  for relay probe information, and a box  62   c  for destination information. In the box  62   a  for source information, identification information of a sender of the radio signals (hereinafter referred to as a source) is displayed. In the box  62   b  for the relay probe information, identification information of a probe (hereinafter referred to as relay probe) used for relaying the radio signals is displayed. In the box  62   c  for destination information, identification information of a final recipient (hereinafter referred to as destination) is displayed. 
     In the box  62   a  for source information, the identification information of the first ultrasonic probe  11  is stored. In the box  62   b  for the relay probe information, the identification information of the second ultrasonic probe  12  is stored. In the case where there are two or more relay probes or access point devices, identification information of each of the relay probes is stored in the box  62   b  in the order of the relay. In the box  62   c  for destination information, the identification information of the ultrasonic observation device  13  is stored. The identification information includes, for example, IP addresses, ID numbers, or the like of the ultrasonic probes  11 ,  12 , and the ultrasonic observation device  13 . In  FIG. 6A , the ID numbers are shown as an example of the identification information. 
     As shown in  FIG. 6B , the route information  58  is based on the route request information  59 . The route request information  59  is composed of the box  61  for route request ID and the route table  62  in the same way as the route information  58  except that the route request information  59  has the blank box  62   b  for the relay probe information and the blank box  62   c  for destination information when the route request information  59  is generated by the routing controller  52   a.    
     Next, with referring to  FIG. 7 , generation of the route information  58  is described. When the observation mode is selected for the first ultrasonic probe  11 , the routing controller  52   a  generates the route request information  59  as shown in the step ( 1 ). 
     Thereafter, in the first ultrasonic probe  11 , the routing controller  52   a  sends the generated route request information  59  to the wireless communication circuit  34   a , and orders the wireless communication circuit  34   a  to broadcast the generated route request information  59 . Here, “to broadcast” is to transmit the same information simultaneously to any number of the ultrasonic probes and/or the ultrasonic observation device  13 . 
     As shown in the step ( 2 ), in the first ultrasonic probe  11 , upon receiving the order to broadcast, the wireless communication circuit  34   a  modulates the route request information  59  into the radio signals and broadcasts them through the antenna  35   a . The second ultrasonic probe  12  is located within the coverage A 1  of the first ultrasonic probe  11 , and receives the radio signals from the first ultrasonic probe  11  through the antenna  35   b.    
     In the second ultrasonic probe  12 , the radio signals received through the antenna  35   b  are demodulated into the route request information  59  by the wireless communication circuit  34   b , and output to the routing controller  52   b . The routing controller  52   b  refers to the route request information  59  and checks whether the identification information of this second ultrasonic probe  12  has already been stored in the route table  62 . If so, it means that this second ultrasonic probe  12  has received the same route request information  59  for the second time. In this case, the routing controller  52   b  of this second ultrasonic probe  12  cancels or discards the route request information  59 . 
     On the other hand, in the case where the identification information of the second ultrasonic probe  12  has not been stored in the route table  62  of the route request information  59 , it means that the second ultrasonic probe  12  has received the route request information  59  for the first time. In this case, the routing controller  52   b  updates the route request information  59  by storing the identification information of the second ultrasonic probe  12  in the box  62   b  for the relay probe information as shown in the step ( 3 ). The identification information is stored as first relay probe information indicating the first relay probe. 
     In the second ultrasonic probe  12 , the routing controller  52   b  sends the updated route request information  59  to the wireless communication circuit  34   b , and orders the wireless communication circuit  34   b  to broadcast the updated route request information  59 . Thereby, as shown in the step ( 4 ), the radio signals into which the route request information  59  is modulated are broadcasted through the antenna  35   b . In the coverage A 3  of the second ultrasonic probe  12 , the first ultrasonic probe  11  and the ultrasonic observation device  13  are located. The first ultrasonic probe  11  receives the radio signals through the antenna  35   a , and the ultrasonic observation device  13  receives the radio signals through the antenna  47 . 
     In the first ultrasonic probe  11 , the radio signals received through the antenna  35   a  are demodulated into the route request information  59  by the wireless communication circuit  34   a . The route request information  59  is input to the routing controller  52   a . Since the identification information of the first ultrasonic probe  11  has already been stored in the route request information  59 , the routing controller  52   a  cancels or discards this route request information  59 . 
     In the ultrasonic observation device  13 , on the other hand, the radio signals received through the antenna  47  are demodulated into the route request information  59  by the wireless communication circuit  42 . The route request information  59  is input to the routing controller  55 . As shown in the step ( 5 ), the routing controller  55  stores the identification information of the ultrasonic observation device  13  in the box  62   c  for destination information of the route request information  59 , and generates the route information  58 . Thus, the transmission route of the radio signals between the first ultrasonic probe  11  and the ultrasonic observation device  13  is determined. 
     Next, as shown in the step ( 6 ), in the ultrasonic observation device  13 , the replication of the route information  58  is stored in the memory  41 . Thereafter, the routing controller  55  sends the route information  58  to the wireless communication circuit  42 , and orders to unicast the route information  58 . Here, “to unicast” is to send information to a single designated recipient. The routing controller  55  refers to the route information  58 , and designates the immediately preceding sender of the route request information  59 , namely, the second ultrasonic probe  12  as the recipient. 
     As shown in the step ( 7 ), in the ultrasonic observation device  13 , the wireless communication circuit  42  modulates the route information  58  into the radio signals upon receiving the order to unicast the route information  58 , and unicasts the radio signals through the antenna  47 . The unicast radio signals are received by the second ultrasonic probe  12 , designated as the recipient, through the antenna  35   b.    
     In the second ultrasonic probe  12 , the received radio signals are demodulated into the route information  58 , and input to the routing controller  52   b . As shown in the step ( 8 ), the routing controller  52   b  stores the copy or replication of the route information  58  in the memory  36   b.    
     Next, in the second ultrasonic probe  12 , as with the routing controller  55  of the ultrasonic observation device  13 , the routing controller  52   b  refers to the route information  58 , and issues an order to the wireless communication circuit  34   b  to unicast the route information  58  to the first ultrasonic probe  11 , which is the source of the route request information  59 , as the designated recipient. Thereby, as shown in the step ( 9 ), the radio signals into which the route information  58  is modulated are unicast through the antenna  35   b.    
     The first ultrasonic probe  11  and the ultrasonic observation device  13  receive the unicast radio signals through the antennas  35   a  and  47 , respectively. The ultrasonic observation device  13  cancels or discards the received radio signals if the designated recipient of the received radio signals is not the ultrasonic observation device  13 . 
     On the other hand, in the first ultrasonic probe  11  designated as the recipient, the received radio signals are demodulated into the route information  58  and input to the routing controller  52   a . As shown in the step ( 10 ), the routing controller  52   a  stores the route information  58  in the memory  36   a . Thus, the route information  58  generated in the ultrasonic observation device  13  is transmitted to the second ultrasonic probe  12  and then to the first ultrasonic probe  11 , retracing the transmission route of the route request information  59 . 
     As described above, the route information  58  is shared among the first ultrasonic probe  11 , the second ultrasonic probe  12 , and the ultrasonic observation device  13 . The radio signals are transmitted and received among the first ultrasonic probe  11 , the second ultrasonic probe  12 , and the ultrasonic observation device  13  without the use of an external radio base station, namely, a wireless communication network is established among the first ultrasonic probe  11 , the second ultrasonic probe  12 , and the ultrasonic observation device  13 . 
     Next, with referring to  FIG. 8 , an operation of the ultrasonic diagnostic apparatus  10  is described. The second ultrasonic probe  12  is turned on and put into the standby mode, and then held in the probe holder  15  as an access point position while being kept in the standby mode. Thereby, the second ultrasonic probe  12  is in a state of an access point device where all functions are disabled except for wireless communication. 
     When the first ultrasonic probe  11  and the ultrasonic observation device  13  are turned on, the CPUs  30   a  and  40  start to control the operations of the first ultrasonic probe  11  and the ultrasonic observation device  13 , respectively. Then, through the operation switch  19   a , the first ultrasonic probe  11  is put into the observation mode to perform the ultrasonic diagnosis. 
     After the first ultrasonic probe  11  is put into the observation mode, the generation of the route information  58  is executed as described with referring to  FIG. 7 . The route information  58  is stored in the memory  36   a  of the first ultrasonic probe  11 , the memory of  36   b  of the second ultrasonic probe  12 , and the memory  41  of the ultrasonic observation device  13 . Thereby, a wireless communication network is established among the first ultrasonic probe  11 , the second ultrasonic probe  12 , and the ultrasonic observation device  13 . 
     An operator places the scan head  16   a  of the first ultrasonic probe  11  on a surface of the body of a patient. In the first ultrasonic probe  11 , the drive signal generating circuit  28   a  sends excitation pulses to the UTs  27   a  selected by the transmission control circuit  31   a , and the ultrasonic waves are emitted from the UTs  27   a  to the object of interest. Every time a transmission and reception of the ultrasonic waves takes place, the UTs  27   a  selected by the transmission control circuit  31   a  are switched or changed sequentially. Thereby, the object of interest is scanned with the ultrasonic waves. The transmission control circuit  31   a  generates the delay pattern information every time a transmission and reception of ultrasonic waves takes place. 
     The emitted ultrasonic waves are reflected by the object of interest, and the UTs  27   a  receive the reflected waves and outputs the detection signals. The detection signals are amplified and digitally modulated in the reception signal processing circuit  29   a . The digitized detection signals are sent to the P/S conversion circuit  33   a , and then modulated into serial signals. The serial signals are sent to the wireless communication circuit  34   a.    
     The communication controller  53   a  of the CPU  30   a  refers to the route information  58  in the memory  36   a , and determines the second ultrasonic probe  12  as the next recipient of the serial signals, and orders the wireless communication circuit  34   a  to unicast the serial signals to the second ultrasonic probe  12 . Thereby, the first ultrasonic probe  11  unicasts the radio serial signals through the antenna  35   a  and the second ultrasonic probe  12  receives the radio serial signals through the antenna  35   b.    
     In the second ultrasonic probe  12 , the radio serial signals are demodulated into the serial signals in the wireless communication circuit  34   b , and temporarily stored in the memory  36   b . Then, the communication controller  53   b  sends the serial signals, stored in the memory  36   b , to the wireless communication circuit  34   b . The communication controller  53   b  refers to the route information  58 , and issues an order to the wireless communication circuit  34   b  to unicast the serial signals to the ultrasonic observation device  13  designated as the next recipient. Thereby, the radio serial signals are unicast from the second ultrasonic probe  12  through the antenna  35   b.    
     The first ultrasonic probe  11  and the ultrasonic observation device  13  receive the radio serial signals through the antennas  35   a  and  47 , respectively. As with the above described unicast transmission of the route request information  59 , the first ultrasonic probe  11  cancels or discards the radio serial signals received through the antenna  35   a.    
     As described above, the second ultrasonic probe  12  relays the radio serial signals transmitted from the first ultrasonic probe  11  to the ultrasonic observation device  13 . The ultrasonic observation device  13  surely receives the signals transmitted from the first ultrasonic probe  11  even if there is an obstruction between the first ultrasonic probe  11  and the ultrasonic observation device  13 . 
     In the first ultrasonic probe  11 , the delay pattern information generated by the transmission control circuit  31   a  is modulated into radio signals, and the radio signals are transmitted concurrently with or after the transmission of the radio serial signals. The radio signals are also relayed to the ultrasonic observation device  13  through the second ultrasonic probe  12 . 
     In the ultrasonic observation device  13 , the communication controller  56  controls the wireless communication circuit  42  to demodulate various radio signals, received through the antenna  47 , into the serial signals and the delay pattern information. The serial signals are sent to the S/P conversion circuit  43 . The delay pattern information is sent to the delay-pattern information storage  48  through the CPU  40 . The S/P conversion circuit  43  performs parallel conversion to convert the input serial signals back into one block of the detection signals and sends the detection signals to the phasing and adding section  49 . 
     The detection signals of all the UTs  27   a  are accumulated in the phasing and adding section  49 , and the delay pattern information is stored in the delay-pattern information storage  48  on a block basis. The phasing and adding section  49  performs phasing and adding of the detection signals based on the delay pattern information stored in the delay-pattern information storage  48 . Thereafter, the detection signals are subjected to various signal processing in the image processor  50  and then modulated into TV signals. The TV signals are subjected to D/A conversion by the display control circuit  45 , and then displayed as an ultrasonic image on the monitor  24 . 
     In the above embodiment, the second ultrasonic probe  12  not being used for the ultrasonic diagnosis is put in the probe holder  15 . The ultrasonic probe  12  may be placed anywhere in an access point position where the coverage A 1  of the first ultrasonic probe  11  and the coverage A 2  of the ultrasonic observation device  13  overlap, for example, the ultrasonic probe  12  may be placed on a bedside table or a chair, or hung from the ceiling. 
     Next, with referring to  FIG. 9 , an ultrasonic diagnostic apparatus  65  of the second embodiment in the present invention is described. The ultrasonic diagnostic apparatus  65  basically has the same configuration as the ultrasonic diagnostic apparatus  10  of the first embodiment. In the following embodiments, a part or member the same as or similar to that in  FIGS. 2 and 5  of the above first embodiment is designated by the same numeral as the first embodiment, and descriptions thereof are omitted. 
     In the ultrasonic diagnostic apparatus  65 , backup data  66  of the radio signals to be relayed through the second ultrasonic probe  12  is generated and stored in the memory  36   b . The CPU  30   b  of the second ultrasonic probe  12  functions as a backup controller  68  and a communication status checker  69 . 
     The backup controller  68  controls the backup of the various signals received by the wireless communication circuit  34   b . The communication status checker  69  checks whether there is a communication failure between the second ultrasonic probe  12  and the ultrasonic observation device  13 . If a communication failure is detected, the communication status checker  69  issues an order to the communication controller  53   b  to retransmit the previously transmitted signals. 
     In  FIG. 10 , an operation of the ultrasonic diagnostic apparatus  65  having the above configuration is described. In the following embodiments, descriptions already described in the first embodiment are omitted. The second ultrasonic probe  12  receives one block of the radio serial signals through the antenna  35   b . The radio serial signals are modulated into the serial signals in the wireless communication circuit  34   b , and then temporarily stored in the memory  36   b.    
     The backup controller  68  copies the serial signals in the memory  36   b  to create the backup data  66 . Thereafter, the serial signals in the memory  36   b  are demodulated into the radio serial signals in the wireless communication circuit  34   b , and then transmitted to the ultrasonic observation device  13  through the antenna  35   b.    
     When the transmission of the radio serial signals is started using the second ultrasonic probe  12 , the communication status checker  69  checks the communication status between the second ultrasonic probe  12  and the ultrasonic observation device  13 . For example, the communication status checker  69  controls the wireless communication circuit  34   b  to send the ultrasonic observation device  13  a request to check the communication status at regular time intervals, and checks whether a reply signal from the ultrasonic observation device  13  is received. The communication status checker  69  judges the communication status good when it receives the reply signal from the ultrasonic observation device  13 . 
     On the other hand, for example, as shown in  FIG. 11 , in the case where a person H is present between the second ultrasonic probe  12  and the ultrasonic observation device  13 , this person H may block the radio signals transmitted from the second ultrasonic probe  12 . Accordingly, the ultrasonic observation device  13  cannot receive the request to check the communication status, and the reply signal is not transmitted from the ultrasonic observation device  13 . Thereby, the communication status checker  69  judges that a communication failure is occurring between the second ultrasonic probe  12  and the ultrasonic observation device  13 . 
     The communication status checker  69  continues the transmission of the communication status request after the judgment of the communication failure. When the person H moves and no longer blocks the communication between the second ultrasonic probe  12  and the ultrasonic observation device  13 , the ultrasonic observation device  13  receives the communication status request and resumes the transmission of the reply signal. 
     In  FIG. 10 , when the ultrasonic observation device  13  resumes the transmission of the reply signal, the communication status checker  69  determines that the communication failure is resolved, so the communication status checker  69  issues an order to the communication controller  53   b  to retransmit the radio serial signals. The communication controller  53   b  reads the backup data stored in the memory  36   b , and controls the wireless communication circuit  34   b  to retransmit the radio serial signals. 
     As described above, the radio serial signals are surely relayed even if the communication between the second ultrasonic probe  12  and the ultrasonic observation device  13  is temporarily interrupted. The above described processes are repeated until the transmission of one block of the radio serial signals is completed. 
     After the completion of the transmission of one block of the radio serial signals, the backup controller  68  deletes the backup data  66  corresponding to the transmitted radio serial signals from the memory  36   b . The subsequent processes are the same as in the first embodiment, and descriptions thereof are omitted. 
     In the above second embodiment, the backup data  66  is sequentially stored in the memory  36   b . However, if the interruption time of the communication between the second ultrasonic probe  12  and the ultrasonic observation device  13  is long, an amount of the backup data  66  stored in the memory  36   b  increases while a remaining capacity of the memory  36   b  decreases. In this case, the second ultrasonic probe  12  and/or the ultrasonic observation device  13  may provide an alarm or warning, for example, an LED lamp or beep sound, to notify the operator the communication failure. 
     In the above second embodiment, the backup of the serial signals is performed in the second ultrasonic probe  12  as an example. Alternatively or in addition, the backup of the serial signals may be performed in the first ultrasonic probe  11 . Information other than the serial signals may also be backed up. For example, the delay pattern information, the route request information  59  and/or the route information  58  may be backed up in the same manner as the above. In the case that the communication status checker  69  determines that the communication failure is occurring, the first ultrasonic probe  11  may stop the ultrasonic scanning, and resume the scanning when the communication failure is resolved. Thereby, power savings are achieved. 
     Next, with referring to  FIG. 12 , an ultrasonic diagnostic apparatus  70  of the third embodiment of the present invention is described. The ultrasonic diagnostic apparatus  70  basically has the same configuration as the ultrasonic diagnostic apparatus  10  shown in  FIG. 1  of the first embodiment except that in the ultrasonic diagnostic apparatus  70 , wireless communication circuits  71   a ,  71   b , and  72 , different from those in the first embodiment, are provided in the first and second ultrasonic probes  11  and  12 , and the ultrasonic observation device  13 , respectively. 
     In the ultrasonic diagnostic apparatus  70 , the CPUs  30   a ,  30   b , and  40  function as alarm controllers  76   a ,  76   b , and  77 , respectively. In addition, alarm LEDs  78   a  and  78   b  are provided in the first and second ultrasonic probes  11  and  12 , respectively. 
     The wireless communication circuits  71   a ,  71   b , and  72  are basically the same as the wireless communication circuits  34   a ,  34   b , and  42  of the first embodiment except that the each of the wireless communication circuits  71   a ,  71   b , and  72  is provided with a received power measuring section  80 . The received power measuring sections  80  measure magnitudes of the received power of the various radio signals received by the wireless communication circuits  71   a ,  71   b , and  72  through the antenna  35   a ,  35   b , and  47 , respectively. 
     Each of the alarm controllers  76   a  of the first ultrasonic probe  11 ,  76   b  of the second ultrasonic probe  12 , and  77  of the ultrasonic observation device  13  controls an alarm or warning, using the alarm LEDs  78   a  and  78   b , indicating degradation of communication quality due to reduction in received power of the radio signals. The alarm controllers  76   a  and  76   b  perform lighting control of the alarm LEDs  78   a  and  78   b . The alarm controller  77  controls the alarm or warning display on the monitor  24  through the display control circuit  45 . 
     With referring to  FIG. 13 , an operation of the ultrasonic diagnostic apparatus  70  having the above configuration is described. The wireless communication circuits  71   a ,  71   b , and  72  of the first and second ultrasonic probes  11 ,  12 , and the ultrasonic observation device  13  actuate the received power measuring sections  80  when the wireless communication circuits  71   a ,  71   b , and  72  receive various radio signals through the antennas  35   a ,  35   b , and  47 , respectively. Sources of the radio signals are not particularly limited. 
     The received power measuring sections  80  measure the received power of the radio signals input to the wireless communication circuits  71   a ,  71   b  and  72 , and output the measurement results to the CPUs  30   a ,  30   b  and  40 , respectively. Based on the measurement results, the alarm controllers  76   a ,  76   b  and  77  monitor whether the received power drops below a predetermined threshold value. The threshold value is set to a value equal to or above which the degradation of communication quality, e.g. communication interruption, does not occur. 
     Each of the alarm controllers  76   a ,  76   b , and  77  judges that the communication quality is good or normal when the measurement result of the received power is equal to or above the threshold value, and continues monitoring of the measurement input from the received power measuring section  80 . On the other hand, when the measurement result drops below the threshold value in the first ultrasonic probe  11 , the alarm controller  76   a  turns on the alarm LED  78   a . When the measurement result drops below the threshold value in the second ultrasonic probe  12 , the alarm controller  76   b  turns on the alarm LED  78   b . The alarm controller  77  of the ultrasonic observation device  13  displays an alarm message and the like on the monitor  24  through the display control circuit  45 . This directs the attention of the operator to move the first or second ultrasonic probe  11  or  12  closer to a source of the radio signals or remove an obstruction to get the communication status back to normal. Thus, the degradation of communication quality among the first and second ultrasonic probes  11  and  12 , and the ultrasonic observation device  13  is prevented. Alarm displays are not particularly limited to the above. Instead or in addition to the alarm LEDs  78   a  and  78   b , audible sounds may be used as the alarm. 
     Next, an ultrasonic diagnostic apparatus  85  of the fourth embodiment of the present invention is described. As shown in  FIG. 14 , in the ultrasonic diagnostic apparatus  85 , multiple ultrasonic probes relay the radio signals, namely, a third ultrasonic probe  86  is added to the ultrasonic diagnostic apparatus having the configuration of the above first, second, or third embodiment. The third ultrasonic probe  86  has the same configuration as the first and second ultrasonic probes  11  and  12 . Hereinafter, a suffix “c” is added to a numeral of a component or part of the third ultrasonic probe  86 . 
     In the ultrasonic diagnostic apparatus  85 , the coverage of the first to third ultrasonic probes  11 ,  12  and  86 , and that of the ultrasonic observation device  13  overlap with each other. Accordingly, the following four routes (1) to (4) for transmitting and receiving the radio signals are available. An optimum transmission route is selected from the routes (1) to (4).
     Route 1: the first ultrasonic probe  11 →the second ultrasonic probe  12 →the third ultrasonic probe  86 →the ultrasonic observation device  13     Route 2: the first ultrasonic probe  11 →the second ultrasonic probe  12 →the ultrasonic observation device  13     Route 3: the first ultrasonic probe  11 →the third ultrasonic probe  86 →the ultrasonic observation device  13     Route 4: the first ultrasonic probe  11 →the ultrasonic observation device  13     

     As shown in  FIG. 15 , the ultrasonic diagnostic apparatus  85  basically has the same configuration as the ultrasonic diagnostic apparatus  70  of the third embodiment which measures the received power of the radio signals, except that a routing controller  88   a  of the first ultrasonic probe  11  generates route request information  89  different from that in the first embodiment. In this route request information  89 , the measurement results of the received power of the radio signals in the relay probe and those in the destination are stored in addition to the identification information. In the route request information  89 , the routing controllers  88   b ,  88   c , and  91  store the measurement results of the received power of the respective measuring sections  80 . 
     In the ultrasonic diagnostic apparatus  85 , the CPU  40  of the ultrasonic observation device  13  functions as the routing controller  91  different from the third embodiment and as a route information selector  92 . In the case where there are four transmission routes of the radio signals, the routing controller  91  generates the first to the fourth route information  93 -( 1 ) to  93 -( 4 ) corresponding to the four transmission routes. The route information selector  92  compares the first to the fourth route information  93 -( 1 ) to  93 -( 4 ), and selects the optimum transmission route. 
     Generation of the first route information  93 -( 1 ) is described with referring to  FIGS. 16A to 16D . As shown in  FIG. 16A , the route request information  89  generated by the routing controller  88   a  is modulated into radio signals and then broadcasted. The broadcast radio signals are received by the second ultrasonic probe  12 . 
     Thereafter, the radio signals are demodulated into the route request information  89 , and then input to the routing controller  88   b . The received power of the radio signals is measured by the received power measuring section  80 . The measurement results are input to the routing controller  88   b.    
     As shown in  FIG. 16B , the routing controller  88   b  stores the measurement results of the received power in the box  62   b  for the relay probe information in association with the identification information of the second ultrasonic probe  12 . Thereafter, the route request information  89  is modulated into the radio signals and then broadcasted, and received by the third ultrasonic probe  86 . 
     Hereinafter, as shown in  FIG. 16C , in the same manner as the above, the routing controller  88   c  of the third ultrasonic probe  86  stores the identification information and the measurement results of the received power, and the route request information  89  is modulated into the radio signals and then broadcasted. Thereafter, as shown in  FIG. 16D , the routing controller  91  of the ultrasonic observation device  13  stores the identification information and the measurement results of the received power. Thus, the first route information  93 -( 1 ) is generated. 
     As shown in  FIGS. 17A to 17C , the second to fourth route information  93 -( 2 ) to  93 -( 4 ) is generated as with the first route information  93 -( 1 ). The first to fourth route information  93 -( 1 ) to  93 -( 4 ) is input from the routing controller  91  to the route information selector  92 . 
     As shown in  FIG. 18 , the route information selector  92  checks the received power values stored in each of the first to fourth route information  93 -( 1 ) to  93 -( 4 ), and picks up the route information in which all of the received power values exceed the above described threshold value. In other words, the route information selector  92  selects the route information not causing the degradation of communication quality as described in the third embodiment. From among the picked up route information, the route information selector  92  selects the route information having the least number of relay probes, or which transmits the radio signals to the ultrasonic observation device  13  in the shortest time. Instead, the route information with the highest received power may be selected. 
     The route information selected by the route information selector  92  is alternately stored in the memory and unicasted as described in  FIG. 7 , and thus the selected route information is shared by the ultrasonic observation device  13 , the second ultrasonic probe  12  used as the relay probe, and the first ultrasonic probe  11 . Using the selected route information, the serial signals from the first ultrasonic probe  11  are transmitted to the ultrasonic observation device  13  via multiple relay probes as access point devices. The multiple relay probes provide the robust and optimum wireless communication network. 
     In the above fourth embodiment, three ultrasonic probes are used. Alternatively, the route information is generated and selected, and the radio signals are relayed among four or more ultrasonic probes as with the above. 
     Next, an ultrasonic diagnostic apparatus  96  of the fifth embodiment of the present invention is described with referring to  FIG. 19 . The ultrasonic diagnostic apparatus  96  is basically the same as the ultrasonic diagnostic apparatus  85  of the above fourth embodiment except that a list of ultrasonic probes is displayed. It should be noted that the ultrasonic diagnostic apparatus  96  uses four or more ultrasonic probes. 
     In the ultrasonic diagnostic apparatus  96 , route information (probe information)  97  selected by the route information selector  92 , a correspondence table  98 , and multiple unselected route information (probe information)  99  is stored in the memory  41  of the ultrasonic observation device  13 . In the ultrasonic diagnostic apparatus  96 , the CPU  40  of the ultrasonic observation device  13  functions as a probe list display controller  100 . 
     In the correspondence table  98 , identification information and name of each of the ultrasonic probe are associated with each other and stored. The unselected route information  99  refers to the route information which is generated by the routing controller  91  but not selected by the route information selector  92 . 
     The probe list display controller  100  generates a probe list  101  based on the route information  97 , the correspondence table  98 , and the unselected route information  99  stored in the memory  41 , and displays the generated probe list  101  on the monitor  24  via the display control circuit  45 . 
     The probe list  101  is composed of a column indicating names of the ultrasonic probes listed in the correspondence table  98 , and a column indicating the usage status of the ultrasonic probes. The usage status include “observing”, “relaying”, “standby”, and “unusable”. 
     The usage status “observing” indicates that the ultrasonic probe is currently used for the ultrasonic diagnosis. The usage status “relay” indicates that the ultrasonic probe is currently used for relaying. The usage status “standby” indicates that the ultrasonic probe is not currently used for the ultrasonic diagnosis and relaying, but usable for those purposes. The usage status “unusable” indicates that the ultrasonic probe is unusable for the ultrasonic diagnosis and relaying, namely, for example, the ultrasonic probe has been turned off. 
     The probe list display controller  100  retrieves the names of the ultrasonic probes in the observing status and those in the relaying status based on the identification information stored in the box  62   a  for source information and the box  62   b  for the relay probe information in the route information  97 , with referring to the correspondence table  98 . Based on the retrieved names, the probe list display controller  100  enters “observing” or “relaying” in a cell of the status column in the probe list  101 . 
     Then the probe list display controller  100  compares the route information  97  and the unselected route information  99 , and picks up the identification information of the ultrasonic probes not stored in the route information  97 , namely, the ultrasonic probes not being used for observation or relaying. The probe list display controller  100  refers to the correspondence table  98  and enters “standby” in the corresponding cells of the status column in the probe list  101 . 
     The probe list controller  100  enters “unusable” in cells of the status column where none of “observing”, “relaying”, and “standby” is entered. 
     The usage status (observing, relaying, standby, or unusable) of the ultrasonic probes is checked by the operator at a glance at the probe list  101  on the monitor  24 . Alternatively, the usage status of each ultrasonic probe may be displayed individually on the monitor  24 . 
     An ultrasonic diagnostic apparatus  104  of the sixth embodiment of the present invention is described with referring to  FIG. 20 . In the ultrasonic diagnostic apparatuses in the above first to fifth embodiments, an instruction input signal is relayed from the first ultrasonic probe  11  being used in the ultrasonic diagnosis to the ultrasonic observation device  13  as with the serial signal when the operation switch  19   a  of the first ultrasonic probe  11  is operated. Examples of the operations performed by inputting the instruction input signals include freezing of an ultrasonic image displayed on the monitor  24  and adjustments in signal processing such as gain correction performed in the image processor  50  of the ultrasonic observation device  13 . 
     On the other hand, the ultrasonic diagnostic apparatus  104  of the sixth embodiment allows the operator to input an operation instruction from the second ultrasonic probe  12 , being used for relaying the radio signals, to be performed by the first ultrasonic probe  11  or the ultrasonic observation device  13 . The ultrasonic diagnostic apparatus  104  has the same configuration as that in the first embodiment, except that a communication controller  105  of the second ultrasonic probe  12  has a different function. 
     The communication controller  105  determines the destination of an instruction input signal when this instruction input signal is input from the operation switch  19   b  to the CPU  30   b . The destination of the instruction input signal conforms to that of the serial signal. Hereinafter, as with the first embodiment, the communication controller  105  transmits the instruction input signal to the wireless communication circuit  34   b , and issues an order to the wireless communication circuit  34   b  to unicast the instruction input signal to the ultrasonic observation device  13  designated as the destination. Thereby, the ultrasonic observation device  13  receives the instruction input signal, and is controlled based on the received instruction input signal. 
     When the operation switch  19   b  of the second ultrasonic probe  12  is used to control the first ultrasonic probe  11 , for example, to change the operation mode, the communication controller  105  refers to the route information  58  and unicasts the instruction input signal to the first ultrasonic probe  11  designated as the destination. Thus, the instruction input signal is transmitted from the second ultrasonic probe  12  to the first ultrasonic probe  11 , and the first ultrasonic probe  11  is controlled based on the received instruction input signal. In other words, the first ultrasonic probe  11  is controlled using the operation switch  19   b  of the second ultrasonic probe  12  as the operation switch  19   a  of the first ultrasonic probe  11 . The scan head  16   a  of the first ultrasonic probe  11  is held with one hand as shown in  FIG. 1 , enabling an operator to operate the operation switch  19   b  with the other hand. 
     As described above, the first ultrasonic probe  11  or the ultrasonic observation device  13  is operated without operating the operation switch  19   a  of the first ultrasonic probe  11  used for the ultrasonic diagnosis. This prevents a displacement of the first ultrasonic probe  11  from its proper examination position caused by the operation of the operation switch  19   a.    
     An ultrasonic diagnostic apparatus  108  of the seventh embodiment of the present invention is described with referring to  FIG. 21 . The ultrasonic diagnostic apparatus  108  has basically the same configuration as the ultrasonic diagnostic apparatus  85  of the fourth embodiment provided with the first to third ultrasonic probes  11 ,  12 , and  86 , except that the third ultrasonic probe  86  and the ultrasonic observation device  13  are connected via wired connection in the ultrasonic diagnostic apparatus  108 . 
     To be more specific, a connection I/F  109  is provided in each of the ultrasonic probes  11 ,  12 , and  86  (only the ultrasonic  86  is shown), and a connection I/F  110  is provided in the ultrasonic observation device  13 . The connection I/F  109  of the third ultrasonic probe  86  and the connection I/F  110  are connected via a cable  111 . The connection I/F  109  is connected to a wireless communication circuit  71   c.    
     The ultrasonic observation device  13  is provided with a connection switching circuit  112  connected to the CPU  40 , the S/P conversion circuit  43 , the wireless communication circuit  72 , and the connection I/F  110 . Under the control of the CPU  40 , the connection switching circuit  112  connects one of the wireless communication circuit  72  and the connection I/F  110  to the CPU  40  and to the S/P conversion circuit  43 . 
     In the case where the third ultrasonic probe  86  is not connected to the connection I/F  110  via the cable  111 , the connection switching circuit  112  connects the wireless communication circuit  72  to the CPU  40  and to the S/P conversion circuit  43 . On the other hand, in the case where the third ultrasonic probe  86  is connected to the connection I/F  110  via the cable  111 , the connection I/F  110  is connected to the CPU  40  and to the S/P conversion circuit  43 . 
     In the case where the third ultrasonic probe  86  and the ultrasonic observation device  13  are connected via the cable  111 , the radio serial signal received by an antenna  35   c  of the third ultrasonic probe  86  is demodulated into the serial signal by the wireless communication circuit  71   c . The serial signal is input to the S/P conversion circuit  43  through the connection I/F  109 , the cable  111 , the connection I/F  110 , and the connection switching circuit  112 . On the other hand, the route information and the like generated by the CPU  40  follows the same path in reverse and are input to the wireless communication circuit  71   c.    
     As described above, the ultrasonic observation device  13  can use the antenna  35   c  and the wireless communication circuit  71   c  of the third ultrasonic probe  86  instead of the antenna  47  and the wireless communication circuit  72  of its own. Even if the second ultrasonic probe  12  and the ultrasonic observation device  13  are far apart and both of them are out of the coverage of the third ultrasonic probe  86 , a wireless communication network can be established by extending the cable  111  and bringing the third ultrasonic probe  86  close to the second ultrasonic probe  12 . A wireless communication network is established even when the antenna  47  or the wireless communication circuit  72  of the ultrasonic observation device  13  is broken. 
     An ultrasonic diagnostic apparatus  115  of the eighth embodiment of the present invention is described with referring to  FIG. 22 . The configuration of the ultrasonic diagnostic apparatus  115  is basically the same as the ultrasonic diagnostic apparatus  10  in the above first embodiment, except that each of the ultrasonic probes  11  and  12  is provided with a relay status LED  116  (the relay status LED  116  is only shown in the second ultrasonic probe  12 ). The relay status LED  116  indicates whether relaying of radio signals is performed. The CPUs  30   a  and  30   b  of the first and second ultrasonic probes  11  and  12  function as relay status display controllers  118 , respectively (the relay status display controller  118  is only shown in the second ultrasonic probe  12 ). 
     The relay status display controller  118  turns on the relay status LED  116  when the ultrasonic probe  12  is used for relaying various radio signals such as radio serial signals, or when the wireless communication circuit  34   b  performs relaying of the radio signals. Thereby, the second ultrasonic probe  12  currently used for relaying is prevented from being used for other purposes by error. Instead of using the relay status LED  116 , the relaying of the radio signals can be notified by an alarm display or audible sound. 
     When the ultrasonic probe is used for relaying, the functions for the ultrasonic diagnostic use may be disabled. Alternatively or in addition, a message may be displayed to confirm whether this ultrasonic probe is available for the diagnostic use. 
     Two or more of the above described first to the eighth embodiments may be used in combination. 
     In each of the above embodiments, only one ultrasonic observation device  13  is provided. The present invention is also applicable to the case where multiple ultrasonic observation devices  13  are provided. In this case, multiple route information having different destinations is generated, and the route information most quickly responded to the first ultrasonic probe  11  is selected. 
     Various changes and modifications are possible in the present invention and may be understood to be within the present invention.