Abstract:
A data transmission system using a human body as a signal transmission path includes a transmitter and a receiver. The transmitter uses a pair of electrodes which are held in close proximity to the skin of the human body. The transmitter transmits data to the receiver through the signal transmission path partly extending through the human body when a user carrying the transmitter touches a touch electrode of the receiver. The electrodes are integrated into a garment worn by the user in such a manner that the electrodes are kept in a closely facing relation to the skin of the user, thereby establishing the electrical path extending through the human body. With the integration of the two electrodes into the garment, the user wearing the garment as an everyday clothes or uniform can be easy and convenient to carry the transmitter for successful transmission of the data.

Description:
BACKGROUND ART  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a data transmission system using a human body as a signal path, and more particularly to a system composed of a wearable transmitter, a receiver adapted to be connected to an associated equipment which utilize data transmitted from the transmitter, and a garment integrally holding two electrodes for passing the data through the human body.  
           [0003]    2. Description of the Prior Art  
           [0004]    U.S. patent application Ser. No. 09/605,357 discloses a data transmission system using the human body as a signal path. The system includes a portable transmitter in the form of a wrist watch to be worn on a user, and a signal receiver. The transmitter has a pair of electrodes on the back of the wrist watch for direct contact with the skin of the user. One electrode acts as a signal electrode which is connected through a portion of the user&#39;s body to a touch electrode of the signal receiver, while the other electrode acts as a ground electrode which is coupled through the other portion of the user&#39;s body to a circuit ground of the signal receiver to complete a signal path through the user&#39;s body for data transmission from the wrist watch to the signal receiver. When using this system used for a verified access to a place or database, however, the user is always required to keep in mind to carry the dedicated wrist watch having the electrodes. This may be sometimes inconvenient and even troublesome for the user who has his own wrist watch.  
         SUMMARY OF THE INVENTION  
         [0005]    In view of the above inconvenience, the present invention has been achieved to provide a data transmission system which is capable of assuring successful data transmission without requiring a special attention to the user. The system in accordance with the present invention comprises a transmitter adapted to be carried by the user and a receiver adapted to be connected to an associated equipment which utilizes data transmitted from the transmitter. The transmitter has a ground electrode to be placed in close proximity to the human body, a signal electrode to be placed also in close proximity to the human body in a spatially spaced relation from the ground electrode, a data memory storing first data, a first modulator for converting the first data into a first modulated voltage signal, and a first signal transmitter which applies the first modulated voltage signal across the signal electrode and the ground electrode. The receiver includes a circuit ground adapted to be connected to the ground, a touch electrode adapted for direct contact with a portion of the human body carrying the transmitter, a signal detector connected across the signal electrode and the circuit ground to detect the first modulated voltage signal, and a demodulator which converts the first modulated voltage signal back into the first data. The characterizing feature of the present invention resides in that the system includes a garment which is adapted to be worn by a user and integrates the ground and signal electrodes in such a manner that at least one of the electrodes is kept in a closely facing relation to the skin of the user, thereby establishing an electrical path extending through a portion of the human body for signal transmission from the transmitter to the receiver. With the integration of the two electrodes into the garment, the user wearing the garment as an everyday clothes or uniform such as a white gown can be easy and convenient to carry the transmitter for successful transmission of the data to the receiver.  
           [0006]    Preferably, each of the ground and signal electrodes is formed by a plurality of electrically conductive threads and is sewed to be integrated into the garment. Thus, the electrodes can be easily integrated into the garment and cannot sacrifice comfortableness of the garment. Each electrode made of the electrically conductive threads can be woven into a fabric so as to be lined on the garment. Alternatively, the electrode of the conductive threads can be woven into an indispensable part of the garment. With the use of the electrical conductive threads, the garment provided with the resulting electrodes can be washed like ordinary clothes, which enhances availability of the system.  
           [0007]    The ground electrode is preferred to be located on the garment closer to the foot of the user than the signal electrode for establishing a consistent electrical path through the human body. That is, the electrical path is composed of a first fraction path extending from the ground electrode down to the foot of the user and through the ground to the circuit ground of the receiver, and a second fraction path extending from the signal electrode towards and through a finger of the user to the touch electrode of the receiver without interfering the first fraction path, thereby assuring efficient and reliable data transmission.  
           [0008]    In a preferred embodiment where both of the ground and signal electrodes are held on the garment so as to come into a closely facing relation with the skin of the user, the transmitter has a case which accommodates an electrical circuitry realizing the first modulator and the first signal transmitter, and which is formed as a separate article from the electrodes. The case is provided with terminals for electrically connecting the circuitry with the ground and signal electrodes. In this connection, the garment is additionally provided with a ground lead and a signal lead which extend respectively from the ground and signal electrodes for connection with the terminals of the case. Both of the ground and signal leads are formed by a strand of the electrically conductive threads and are sewed on the garment. Thus, the leads can be also easily and consistently integrated into the garment to retain comfortableness of the garment.  
           [0009]    A coupling member is included in the system to make the case detachable from the garment and at the same time make the electrical circuitry detachable from the electrodes, i.e., the corresponding leads. The coupling member may be realized by a spring-loaded clip which is pivotally supported to the case so as to be movable between a pinching position and a release position. The clip is formed with the terminals which are electrically isolated from each other for connection respectively with the ground and signal leads at the pinching position.  
           [0010]    Instead of the clip, the coupling member may comprise a pair of first fasteners each composed of one of a socket and a ball forming a snap button for mounting the case to the garment, and a pair of second fasteners each composed of the other of the socket and the ball. The first fasteners are fixed on the case and connected across the first signal transmitter of the circuitry, while the second fasteners are fixed on the garment and are permanently connected to respectively to the ground and signal electrodes. When using the snap button to make the case detachable from the garment, the second fasteners are preferably held in direct contact with the ground and signal electrodes, respectively formed of the electrically conductive threads, thereby substantially eliminating the leads from the garment. In this connection, the ground and signal electrodes may be in the form of annular bands provided inside of a sleeve of the garment in a spaced relation from each other along the length of the sleeve.  
           [0011]    Preferably, the case is made water-tight for sealing the electric circuitry so that the garment can be washed like ordinal clothes even with the case. Further, the case may be in the form of a plate which encapsulate the circuitry and a battery energizing the circuitry. Thus, the plate can be utilized also as a nameplate as is usual with the white gown worn by a physician, nurse, and a laboratory worker.  
           [0012]    These and still other objects and advantageous features will become more apparent from the following description of the preferred embodiments when taken in conjunction with the attached drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a schematic view illustrating a basic concept of a data transmission system in accordance with the present invention;  
         [0014]    [0014]FIG. 2 is a block diagram of a wearable transmitter utilized in the above system;  
         [0015]    [0015]FIG. 3 is a block diagram of an associated receiver utilized in the above system;  
         [0016]    [0016]FIGS. 4 and 5 are front and rear views of a garment utilized in the above system to integrate a ground electrode and a signal electrode;  
         [0017]    [0017]FIG. 6 is a perspective view showing one typical application of the above system;  
         [0018]    [0018]FIG. 7 is a rear perspective view of a case in the form of a nameplate accommodating an electric circuitry of the transmitter and detachable to the garment;  
         [0019]    [0019]FIG. 8 is a perspective view of the case and a portion of the garment to which the case is attached;  
         [0020]    [0020]FIG. 9 is a view showing the nameplate as attached to the garment;  
         [0021]    [0021]FIG. 10 is schematic view illustrating another embodiment of the system;  
         [0022]    [0022]FIG. 11 is an exploded perspective view showing ground and signal electrodes integrated into a sleeve of the garment and a transmitter case detachable thereto; and  
         [0023]    [0023]FIG. 12 is a side view of the transmitter case. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0024]    Referring first to FIG. 1, there is shown a principle of a data transmission system using a human body as a signal transmission path. The system includes a wearable transmitter  10  adapted to be worn on the human body, and a receiver  40  adapted to be connected to an equipment such as a personal computer  60  which utilizes data transmitted from the transmitter for controlled operation of the computer  60 , for example, a verified log-in of the user. The transmitter  10  is connected to a ground electrode  31  and a signal electrode  32  which are integrated into a garment  30  worn by a user in close proximity to the skin of the user. When the user carrying the transmitter  10  touches a touch electrode  41  of the receiver  40 , a signal path is established which extends from the signal electrode  32  through a portion of the user&#39;s body, the touch electrode  41 , an internal circuit of the receiver  40 , a circuit ground  49  of the receiver  40 , the ground G, the other portion of the user&#39;s body, the ground electrode  31  and an internal circuit of the transmitter  10 . The signal path extending through the human body is indicated by dotted lines. Thus, a voltage signal applied across the electrodes  31  and  32  is transmitted to the receiver  40  when the user touches the touch electrode  41 . In FIG. 1, the circuit ground of the receiver  40  is connected to the ground G through a ground line  64  common to the computer  60  for the sake of simplicity. However, the circuit ground may be capacitively connected to the ground G or even capacitively connected directly to the major portion of the user&#39;s body for establishing the signal path.  
         [0025]    As shown in FIG. 2, the transmitter  10  includes an electric circuitry and a battery  12  which are accommodated within a case  11 . The circuitry includes a data memory  13  storing data to be transmitted, a controller  14 , a modulator  15  modulating the data into a modulated voltage signal, a signal transmitter  16  applying the modulated voltage signal across the signal electrode  32  and the ground electrode  31  on the garment  30 . Also included in the circuitry is a signal detector  20  which is connected to detect a start signal transmitted from the receiver  40  through the signal electrode  32 . The start signal is received across the signal electrode  32  and a circuit ground  19 . The circuit ground  19  may be connected to the ground electrode  31 . Only the controller  14  and the signal detector  20  are constantly energized by the battery  12  to be ready for detecting the start signal from the receiver  40 . In the non-operative condition where the transmitter  10  is not transmitting the data, the controller  14  is kept in a sleep mode of consuming less electric current from the battery  12 . When the start signal is received as a consequence of the user touching the touch electrode  41 , the signal detector  20  wakes up the controller  14  which in turn energizes the data memory  13 , the modulator  15 , and the signal transmitter  16  to apply the modulated voltage signal across the signal electrode  32  and the ground electrode  31  for initiating the data transmission. The controller  14  incorporates a timer which starts upon detection of the start signal to provide a predetermined time during which the data is transmitted. After the elapse of the predetermined time, the controller  14  responds to deenergize the modulator  15 , the signal transmitter  16  and the data memory  13 . For this purpose, the controller  14  includes power switches  21  and  22  which are actuated by the signal detector  20  and the timer to selectively energize and deenergize the modulator  15 , the signal transmitter  16  and the data memory  13 . Dotted lines in FIG. 2 show power supply lines from the battery  12 . Thus, after transmitting the data, the controller  14  goes back into the sleep mode of consuming less current or energy but being kept ready to detect of the start signal for another data transmission. The transmitter  10  optionally includes a display  24  for visual indication of the data stored in the data memory  15 .  
         [0026]    As shown in FIG. 3, the receiver  40  includes various circuits connected to the touch electrode  41  on the exterior of a housing of the receiver. The circuits are energized by a power source  61  provided in the computer  60  to which the receiver  40  is attached. The circuits are commonly connected to a circuit ground  49  which is in turn connected to a ground terminal  69  of the computer for connection with the ground. The circuits include a touch sensor  42  which is connected to the touch electrode  41  to give a touch signal when the touch electrode  41  is touched by the user&#39;s body. Also included in the circuits are a start signal generator  43 , a signal detector  44 , a demodulator  45 , and a controller  46  which controls the operations of the circuits. The signal transmitter  43  applies the start signal to the touch electrode  41  in response to the touch signal. The signal detector  44  detects the modulated voltage signal which is transmitted from the transmitter  10  and received across the touch electrode  41  and the circuit ground  49 . The modulated voltage signal thus detected is demodulated at the demodulator  45  to derive the first data which is then fed to the computer  60  to be processed thereat. For example, the first data includes a user&#39;s identification code which is verified at a processor  62  of the computer with reference to various codes assigned to different users and stored in a data memory  63 . When the user&#39;s ID is verified as a correct one, the computer completes the log-in sequence to permit the access by the user.  
         [0027]    Under the non-operating condition where the touch electrode  41  is not touched by the human body, only the controller  46  and the touch sensor  42  are energized to be ready for detection of the touching. Upon the touch electrode  41  being touched, the touch sensor  42  gives the touch signal to the controller  46  which responds to close switches  51  and  52  to energize the signal transmitter  43 , the signal detector  44 , and the demodulator  45 , thereby generating the start signal and making the circuits ready for receiving the data from the transmitter  10 . The controller  46  also includes a timer which starts, upon receiving the touch signal, to provide a predetermined time interval during which the data transmission from the first transceiver  10  is expected to complete. After the elapse of the predetermined time interval, the controller  46  responds to open the switches  51  and  52 , deenergizing the signal transmitter  43 , the signal detector  44 , and the demodulator  45 . Thus, the receiver  40  is kept in a sleep mode of consuming less electricity until the touch electrode  41  is touched. Dotted lines in FIG. 3 show power supply lines. The receiver  40  further includes an interface  54  in the form of the USB for transferring the data to the computer  60  as well as for receiving the power from a power supply  61 .  
         [0028]    Further, the transmitter  10  and the receiver  40  are designed to effect a bilateral data transmission therebetween. For this purpose, the transmitter  10  additionally includes a demodulator  25  for demodulating data transmitted from the receiver  40  and that the receiver  40  additionally includes a modulator  47  for modulating the data to be transmitted from the receiver  40 . The modulator  47  of gives a modulated voltage signal indicative of the data to be transmitted to the transmitter  10 . The signal transmitter  43  of the receiver  40  is responsible for applying the modulated voltage signal to the touch electrode  41  for data transmission back to the transmitter  10 .  
         [0029]    In operation, when the user touches the touch electrode  41  of the receiver  40 , the touch sensor  42  provides a touch signal in response to which the controller  46  energizes the modulator  47 , the signal transmitter  43 , the demodulator  45 , and the signal detector  44 . At first, the controller  46  retrieves the data from the data memory  63  of the computer  60  and instructs to give and apply the modulated voltage signal indicative of the data. In response to the voltage signal from the receiver  40 , the controller  14  of the transmitter  10  activates the data memory  13  and performs a suitable processing of the data from the data memory  13  in consideration of the data received from the receiver  40 . The controller  14  updates the data of the data memory  13  depending upon the result of the processing. Thereafter, the controller  14  activates the modulator  15  and the signal transmitter  16  so as to transmit the modulated voltage signal indicative of the updated data to the receiver  40  through the electrodes  31  and  32 . The modulated voltage signal received at the receiver  40  is converted into the data which is utilized by the controller  46  for a controlled operation of the computer or passed to another equipment to be processed thereat for a specific operation of the equipment. In this manner, the two-way data transmission is made between the transmitter and the receiver in a half-duplex manner. Depending upon a specific application to which the system is applied, the system may be designed to have more than one data transmission cycles in which the one-way data transmission from either of the transmitter and the receiver repeats twice or more. In such case, the data in the data memory  13  of the transmitter  10  is modified or updated by the data transmitted from the receiver  40 .  
         [0030]    Also, for minimizing energy consumption, the transmitter  10  is kept in the sleep mode until the modulated voltage signal is received from the receiver  40 , and comes back again in the sleep mode after the data transmission between the transmitter and the receiver is completed. In other words, the data memory  13 , the modulator  15 , the signal transmitter  16 , and the demodulator  21  are energized by closure of the switches  21  and  22  only for a predetermined time period starting from receiving the modulated voltage signal from the receiver. It is within the predetermined time period that the data transmission between the transmitter and the receiver is completed. Likewise, the receiver is kept in the sleep mode until the touch electrode  41  is touched by the human body, and come back to the sleep mode after the data transmission between the first and second transceivers are completed. Thus, the signal transmitter  43 , the modulator  47 , the signal detector  44 , and the demodulator  45  are energized by closure of switches  51  and  52  only for a predetermined time period starting from the touch electrode being touched.  
         [0031]    As shown in FIGS. 1, 4, and  5 , the garment  30  to which the electrodes  31  and  32  are attached is selected, for example, as a white gown that is always worn by a particular user like a physician, nurse, and laboratory worker while engaging a job requiring a verification of the user. As a matter of course, the garment  30  is not limited to the white gown and may take various types of the clothes such as a uniform for an office, factory, school, and the like organization or group. Each of the ground electrode  31  and the signal electrode  32  is in the form of a fabric made by electrically conductive threads and is sewed on the inner surface of the garment  30  with the signal electrode  32  disposed at the shoulders of the garment  30  and with the ground electrode  31  disposed around the lower part of the garment corresponding to a hip and buttocks of the user, as shown in FIGS. 4 and 5. Instead of being lined on the garment, the electrodes may be woven into the garment as indispensable parts thereof. The above selected location of the electrodes  31  and  32  is particularly effective when the user access the computer  60  while sitting on a chair as shown in FIG. 6. In this condition, the ground electrode  31  receives a counter force from the seat of the chair to be pressed against the buttocks of the user, while the signal electrode  32  is pressed against the shoulders of the user with the help of weight of the garment for reliable electrical connection of the electrodes to the human body. It is noted in this connection that the ground electrode  31  is located closer to the foot of the user than the signal electrode  32  along the signal path extending through the human body so that the path extending from the signal electrode  32  toward the finger of the user can be substantially free from, i.e., cannot be substantially interfered with the path extending from the ground electrode  31  to the foot of the user for reliable signal transmission between the transmitter  10  and the receiver  40 .  
         [0032]    As shown in FIG. 7, the case  11  of the transmitter  10  is formed into a nameplate which is made water-tight and accommodates therein the electric circuitry  28  forming the various functional circuits and elements as shown in FIG. 2, and the battery  12  energizing the circuits. The case  11  is provided with a spring-loaded clip  70  so as to be detachable to the garment, for example, at a breast pocket. The clip  70  is pivotally supported at its one end to the case so as to be movable between a pinching position and a release position. The clip  70  includes a pair of conductive terminals  71  and  72  which are connected to the electric circuitry, i.e., across the signal transmitter  16  and which are isolated by a dielectric strip  73 . As shown in FIGS. 8 and 9, when the case  11  is attached to the garment, i.e., the breast pocket, the terminals  71  and  72  come into engagement respectively with pads  35  and  36  provided at one ends of respective leads  33  and  34  extending from the individual electrodes  31  and  32 . Thus, the electric circuitry of the transmitter is connected to electrodes. In this connection, the leads  33  and  34  are also made of electrically conductive threads, more particularly, strands of the conductive threads sewed on or into the garment  30 .  
         [0033]    FIGS.  10  to  12  show another preferred embodiment of the present invention in which a case  11 A of the transmitter  10 A is detachable to a sleeve of the garment  30  by means of snap buttons which are normally utilized in association with clothing. That is, the snap button is made of conductive material and composed of a socket  81  and a ball  82 . In this connection, a ground electrode  31 A and a signal electrode  32 A are provided at the sleeve of the garment  30  for direct coupling with the electric circuitry of the transmitter  10 A. Other structures are identical to the above embodiment and therefore no duplicated explanation is made herein. The case  11 A is in the form of a water-tight thin plate accommodating the electric circuitry  28 A of the transmitter  10 A and the battery  12 A. The case  11 A is provided with a pair of the sockets  81  which are internally connected to the electrical circuitry of the transmitter  10 A, while the electrodes  31 A and  32 A are provided respectively with the balls  82 . As in the previous embodiment, each electrode is made of conductive threads woven and sewed on or into the sleeve to form an annular band surrounding the sleeve in close proximity to the skin of the user wearing the garment for establishing a reliable electrical connection to the human body. In this embodiment, the balls  82  are sewed directly on the electrodes by use of the conductive threads or press-fitted into the electrode, thereby eliminating the leads extending otherwise by a certain distance along the garment from the electrodes. Alternatively, the balls may be provided on the case, or a mixed pair of the ball and socket is provide on the case.  
         [0034]    In the illustrated embodiments, the ground and signal electrodes  31  and  32  are explained to be formed by the electrically conductive threads, however, the each electrode may be formed as a metal plating deposited on the surface of the garment or deposited on a fabric which is sewed on the garment. Also, it is noted that the garment into which the electrodes are integrated is not limited to the garment like the white gown and may be any other kinds of the clothing that is constantly worn by the user who is in access to the verified system. Therefore, the clothing may include an armband and wristband integrating the electrodes to which the case of the transmitter can be made electrically and physically detachable by use of the above described snap buttons.  
         [0035]    Further, the illustrated embodiments show only one application where both of the electrodes are kept in close facing relation with the skin of the user so that both of the electrodes are in direct electrical connection to the user&#39;s body, however, it is equally possible that one of the electrodes is in direct facing relation, i.e., electrical connection to the user&#39;s body, while the other of the electrodes is arranged to face away from the user&#39;s skin for capacitive connection to the receiver through the air.  
         [0036]    Still further, although the illustrated embodiment is arranged to verify the data, i.e., the user&#39;s ID at the computer  60 , the receiver  40  may be arranged to equip the processor and the data memory so as to have a function of verifying the data from the transmitter, and providing a verified output to an associated device for permitting the access or a required control of the device, for example, permitting an entry of the user into a restricted area.