Data transmission system using a human body as a signal transmission path

CROSS-REFERENCE TO RELATED APPLICATIONS

0001The present patent document is a continuation of U.S. application Ser. No. 09/948,638 filed on Sep. 10, 2001, and in turn claims priority to JP 2001-138479 filed on May 9, 2001, the entire contents of each of which are herein incorporated by reference.

BACKGROUND ART

00021. Field of the Invention

0003The 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.

00042. Description of the Prior Art

0005U.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'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's body to a circuit ground of the signal receiver to complete a signal path through the user'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

0006In 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.

0007Preferably, 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.

0008The 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.

0009In 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.

0010A 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.

0011Instead 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.

0012Preferably, 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.

0013These 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

0014<figref idref="DRAWINGS">FIG. 1</figref> is a schematic view illustrating a basic concept of a data transmission system in accordance with the present invention;

0015<figref idref="DRAWINGS">FIG. 2</figref> is a block diagram of a wearable transmitter utilized in the above system;

0016<figref idref="DRAWINGS">FIG. 3</figref> is a block diagram of an associated receiver utilized in the above system;

0017<figref idref="DRAWINGS">FIGS. 4 and 5</figref> are front and rear views of a garment utilized in the above system to integrate a ground electrode and a signal electrode;

0018<figref idref="DRAWINGS">FIG. 6</figref> is a perspective view showing one typical application of the above system;

0019<figref idref="DRAWINGS">FIG. 7</figref> 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;

0020<figref idref="DRAWINGS">FIG. 8</figref> is a perspective view of the case and a portion of the garment to which the case is attached;

0021<figref idref="DRAWINGS">FIG. 9</figref> is a view showing the nameplate as attached to the garment;

0022<figref idref="DRAWINGS">FIG. 10</figref> is schematic view illustrating another embodiment of the system;

0023<figref idref="DRAWINGS">FIG. 11</figref> is an exploded perspective view showing ground and signal electrodes integrated into a sleeve of the garment and a transmitter case detachable thereto; and

0024<figref idref="DRAWINGS">FIG. 12</figref> is a side view of the transmitter case.

DETAILED DESCRIPTION OF THE EMBODIMENTS

0025Referring first to <figref idref="DRAWINGS">FIG. 1</figref>, 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 <b>10</b> adapted to be worn on the human body, and a receiver <b>40</b> adapted to be connected to an equipment such as a personal computer <b>60</b> which utilizes data transmitted from the transmitter for controlled operation of the computer <b>60</b>, for example, a verified log-in of the user. The transmitter <b>10</b> is connected to a ground electrode <b>31</b> and a signal electrode <b>32</b> which are integrated into a garment <b>30</b> worn by a user in close proximity to the skin of the user. When the user carrying the transmitter <b>10</b> touches a touch electrode <b>41</b> of the receiver <b>40</b>, a signal path is established which extends from the signal electrode <b>32</b> through a portion of the user's body, the touch electrode <b>41</b>, an internal circuit of the receiver <b>40</b>, a circuit ground <b>49</b> of the receiver <b>40</b>, the ground G, the other portion of the user's body, the ground electrode <b>31</b> and an internal circuit of the transmitter <b>10</b>. The signal path extending through the human body is indicated by dotted lines. Thus, a voltage signal applied across the electrodes <b>31</b> and <b>32</b> is transmitted to the receiver <b>40</b> when the user touches the touch electrode <b>41</b>. In <figref idref="DRAWINGS">FIG. 1</figref>, the circuit ground of the receiver <b>40</b> is connected to the ground G through a ground line <b>64</b> common to the computer <b>60</b> 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's body for establishing the signal path.

0026As shown in <figref idref="DRAWINGS">FIG. 2</figref>, the transmitter <b>10</b> includes an electric circuitry and a battery <b>12</b> which are accommodated within a case <b>11</b>. The circuitry includes a data memory <b>13</b> storing data to be transmitted, a controller <b>14</b>, a modulator <b>15</b> modulating the data into a modulated voltage signal, a signal transmitter <b>16</b> applying the modulated voltage signal across the signal electrode <b>32</b> and the ground electrode <b>31</b> on the garment <b>30</b>. Also included in the circuitry is a signal detector <b>20</b> which is connected to detect a start signal transmitted from the receiver <b>40</b> through the signal electrode <b>32</b>. The start signal is received across the signal electrode <b>32</b> and a circuit ground <b>19</b>. The circuit ground <b>19</b> may be connected to the ground electrode <b>31</b>. Only the controller <b>14</b> and the signal detector <b>20</b> are constantly energized by the battery <b>12</b> to be ready for detecting the start signal from the receiver <b>40</b>. In the non-operative condition where the transmitter <b>10</b> is not transmitting the data, the controller <b>14</b> is kept in a sleep mode of consuming less electric current from the battery <b>12</b>. When the start signal is received as a consequence of the user touching the touch electrode <b>41</b>, the signal detector <b>20</b> wakes up the controller <b>14</b> which in turn energizes the data memory <b>13</b>, the modulator <b>15</b>, and the signal transmitter <b>16</b> to apply the modulated voltage signal across the signal electrode <b>32</b> and the ground electrode <b>31</b> for initiating the data transmission. The controller <b>14</b> 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 <b>14</b> responds to deenergize the modulator <b>15</b>, the signal transmitter <b>16</b> and the data memory <b>13</b>. For this purpose, the controller <b>14</b> includes power switches <b>21</b> and <b>22</b> which are actuated by the signal detector <b>20</b> and the timer to selectively energize and deenergize the modulator <b>15</b>, the signal transmitter <b>16</b> and the data memory <b>13</b>. Dotted lines in <figref idref="DRAWINGS">FIG. 2</figref> show power supply lines from the battery <b>12</b>. Thus, after transmitting the data, the controller <b>14</b> 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 <b>10</b> optionally includes a display <b>24</b> for visual indication of the data stored in the data memory <b>15</b>.

0027As shown in <figref idref="DRAWINGS">FIG. 3</figref>, the receiver <b>40</b> includes various circuits connected to the touch electrode <b>41</b> on the exterior of a housing of the receiver. The circuits are energized by a power source <b>61</b> provided in the computer <b>60</b> to which the receiver <b>40</b> is attached. The circuits are commonly connected to a circuit ground <b>49</b> which is in turn connected to a ground terminal <b>69</b> of the computer for connection with the ground. The circuits include a touch sensor <b>42</b> which is connected to the touch electrode <b>41</b> to give a touch signal when the touch electrode <b>41</b> is touched by the user's body. Also included in the circuits are a start signal generator <b>43</b>, a signal detector <b>44</b>, a demodulator <b>45</b>, and a controller <b>46</b> which controls the operations of the circuits. The signal transmitter <b>43</b> applies the start signal to the touch electrode <b>41</b> in response to the touch signal. The signal detector <b>44</b> detects the modulated voltage signal which is transmitted from the transmitter <b>10</b> and received across the touch electrode <b>41</b> and the circuit ground <b>49</b>. The modulated voltage signal thus detected is demodulated at the demodulator <b>45</b> to derive the first data which is then fed to the computer <b>60</b> to be processed thereat. For example, the first data includes a user's identification code which is verified at a processor <b>62</b> of the computer with reference to various codes assigned to different users and stored in a data memory <b>63</b>. When the user's ID is verified as a correct one, the computer completes the log-in sequence to permit the access by the user.

0028Under the non-operating condition where the touch electrode <b>41</b> is not touched by the human body, only the controller <b>46</b> and the touch sensor <b>42</b> are energized to be ready for detection of the touching. Upon the touch electrode <b>41</b> being touched, the touch sensor <b>42</b> gives the touch signal to the controller <b>46</b> which responds to close switches <b>51</b> and <b>52</b> to energize the signal transmitter <b>43</b>, the signal detector <b>44</b>, and the demodulator <b>45</b>, thereby generating the start signal and making the circuits ready for receiving the data from the transmitter <b>10</b>. The controller <b>46</b> 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 <b>10</b> is expected to complete. After the elapse of the predetermined time interval, the controller <b>46</b> responds to open the switches <b>51</b> and <b>52</b>, deenergizing the signal transmitter <b>43</b>, the signal detector <b>44</b>, and the demodulator <b>45</b>. Thus, the receiver <b>40</b> is kept in a sleep mode of consuming less electricity until the touch electrode <b>41</b> is touched. Dotted lines in <figref idref="DRAWINGS">FIG. 3</figref> show power supply lines. The receiver <b>40</b> further includes an interface <b>54</b> in the form of the USB for transferring the data to the computer <b>60</b> as well as for receiving the power from a power supply <b>61</b>.

0029Further, the transmitter <b>10</b> and the receiver <b>40</b> are designed to effect a bilateral data transmission therebetween. For this purpose, the transmitter <b>10</b> additionally includes a demodulator <b>25</b> for demodulating data transmitted from the receiver <b>40</b> and that the receiver <b>40</b> additionally includes a modulator <b>47</b> for modulating the data to be transmitted from the receiver <b>40</b>. The modulator <b>47</b> of gives a modulated voltage signal indicative of the data to be transmitted to the transmitter <b>10</b>. The signal transmitter <b>43</b> of the receiver <b>40</b> is responsible for applying the modulated voltage signal to the touch electrode <b>41</b> for data transmission back to the transmitter <b>10</b>.

0030In operation, when the user touches the touch electrode <b>41</b> of the receiver <b>40</b>, the touch sensor <b>42</b> provides a touch signal in response to which the controller <b>46</b> energizes the modulator <b>47</b>, the signal transmitter <b>43</b>, the demodulator <b>45</b>, and the signal detector <b>44</b>. At first, the controller <b>46</b> retrieves the data from the data memory <b>63</b> of the computer <b>60</b> and instructs to give and apply the modulated voltage signal indicative of the data. In response to the voltage signal from the receiver <b>40</b>, the controller <b>14</b> of the transmitter <b>10</b> activates the data memory <b>13</b> and performs a suitable processing of the data from the data memory <b>13</b> in consideration of the data received from the receiver <b>40</b>. The controller <b>14</b> updates the data of the data memory <b>13</b> depending upon the result of the processing. Thereafter, the controller <b>14</b> activates the modulator <b>15</b> and the signal transmitter <b>16</b> so as to transmit the modulated voltage signal indicative of the updated data to the receiver <b>40</b> through the electrodes <b>31</b> and <b>32</b>. The modulated voltage signal received at the receiver <b>40</b> is converted into the data which is utilized by the controller <b>46</b> 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 <b>13</b> of the transmitter <b>10</b> is modified or updated by the data transmitted from the receiver <b>40</b>.

0031Also, for minimizing energy consumption, the transmitter <b>10</b> is kept in the sleep mode until the modulated voltage signal is received from the receiver <b>40</b>, 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 <b>13</b>, the modulator <b>15</b>, the signal transmitter <b>16</b>, and the demodulator <b>21</b> are energized by closure of the switches <b>21</b> and <b>22</b> 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 <b>41</b> 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 <b>43</b>, the modulator <b>47</b>, the signal detector <b>44</b>, and the demodulator <b>45</b> are energized by closure of switches <b>51</b> and <b>52</b> only for a predetermined time period starting from the touch electrode being touched.

0032As shown in <figref idref="DRAWINGS">FIGS. 1, 4</figref>, and <b>5</b>, the garment <b>30</b> to which the electrodes <b>31</b> and <b>32</b> 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 <b>30</b> 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 <b>31</b> and the signal electrode <b>32</b> is in the form of a fabric made by electrically conductive threads and is sewed on the inner surface of the garment <b>30</b> with the signal electrode <b>32</b> disposed at the shoulders of the garment <b>30</b> and with the ground electrode <b>31</b> disposed around the lower part of the garment corresponding to a hip and buttocks of the user, as shown in <figref idref="DRAWINGS">FIGS. 4 and 5</figref>. 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 <b>31</b> and <b>32</b> is particularly effective when the user access the computer <b>60</b> while sitting on a chair as shown in <figref idref="DRAWINGS">FIG. 6</figref>. In this condition, the ground electrode <b>31</b> receives a counter force from the seat of the chair to be pressed against the buttocks of the user, while the signal electrode <b>32</b> 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 <b>31</b> is located closer to the foot of the user than the signal electrode <b>32</b> along the signal path extending through the human body so that the path extending from the signal electrode <b>32</b> 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 <b>31</b> to the foot of the user for reliable signal transmission between the transmitter <b>10</b> and the receiver <b>40</b>.

0033As shown in <figref idref="DRAWINGS">FIG. 7</figref>, the case <b>11</b> of the transmitter <b>10</b> is formed into a nameplate which is made water-tight and accommodates therein the electric circuitry <b>28</b> forming the various functional circuits and elements as shown in <figref idref="DRAWINGS">FIG. 2</figref>, and the battery <b>12</b> energizing the circuits. The case <b>11</b> is provided with a spring-loaded clip <b>70</b> so as to be detachable to the garment, for example, at a breast pocket. The clip <b>70</b> 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 <b>70</b> includes a pair of conductive terminals <b>71</b> and <b>72</b> which are connected to the electric circuitry, i.e., across the signal transmitter <b>16</b> and which are isolated by a dielectric strip <b>73</b>. As shown in <figref idref="DRAWINGS">FIGS. 8 and 9</figref>, when the case <b>11</b> is attached to the garment, i.e., the breast pocket, the terminals <b>71</b> and <b>72</b> come into engagement respectively with pads <b>35</b> and <b>36</b> provided at one ends of respective leads <b>33</b> and <b>34</b> extending from the individual electrodes <b>31</b> and <b>32</b>. Thus, the electric circuitry of the transmitter is connected to electrodes. In this connection, the leads <b>33</b> and <b>34</b> are also made of electrically conductive threads, more particularly, strands of the conductive threads sewed on or into the garment <b>30</b>.

0034<figref idref="DRAWINGS">FIG. 10</figref> to <b>12</b> show another preferred embodiment of the present invention in which a case <b>11</b>A of the transmitter <b>10</b>A is detachable to a sleeve of the garment <b>30</b> 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 <b>81</b> and a ball <b>82</b>. In this connection, a ground electrode <b>31</b>A and a signal electrode <b>32</b>A are provided at the sleeve of the garment <b>30</b> for direct coupling with the electric circuitry of the transmitter <b>10</b>A. Other structures are identical to the above embodiment and therefore no duplicated explanation is made herein. The case <b>11</b>A is in the form of a water-tight thin plate accommodating the electric circuitry <b>28</b>A of the transmitter <b>10</b>A and the battery <b>12</b>A. The case <b>11</b>A is provided with a pair of the sockets <b>81</b> which are internally connected to the electrical circuitry of the transmitter <b>10</b>A, while the electrodes <b>31</b>A and <b>32</b>A are provided respectively with the balls <b>82</b>. 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 <b>82</b> 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.

0035In the illustrated embodiments, the ground and signal electrodes <b>31</b> and <b>32</b> 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.

0036Further, 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's body, however, it is equally possible that one of the electrodes is in direct facing relation, i.e., electrical connection to the user's body, while the other of the electrodes is arranged to face away from the user's skin for capacitive connection to the receiver through the air.

0037Still further, although the illustrated embodiment is arranged to verify the data, i.e., the user's ID at the computer <b>60</b>, the receiver <b>40</b> 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.