TECHNICAL FIELD The present invention relates to a connection structure of twisted pair wires and a near magnetic field non-contact communication device using the connection structure.

BACKGROUND ART In a vehicle, a wire harness is usually used for electrically connecting electronic control units (ECU).

Fig. 10 is a view showing an example of the electric connection structure for connecting ECUs. ECUs 51,61, 71,81 are electrically connected with each other by the mixed wire harness 100 having an electric power supply wire and a signal wire mixed with each other. The mixed wire harness 100 branches to connect the ECUs 51,61, 71,81.

In some cases, a twisted pair wire is used for transmitting signals between ECUs. When the twisted pair wire is used, it is possible to reduce an influence given from the outside noise. In the case where the twisted pair wire is used for signal transmission between ECUs and further it is necessary

to transmit a signal to another ECU, the twisted pair wire is branched so that the branched line can be connected with another ECU.

Fig. 11 is a view showing a first related connection structure of twisted pair wires. In Fig. 11, a main twisted pair wire 101 for transmitting a signal from ECU 51 to ECU 71 is connected to a branch twisted pair wire 102 for transmitting the signal from ECU 51 to ECU 61 as a branch structure. In this connection structure, core wires 102a of the branch twisted pair wire 102, end portions of which are exposed when only the sheath is cut off and removed, are connected with core wires 101 a of the main twisted pair wire 101, which are exposed at the intermediate portions of the main twisted pair wire 101 when only the sheath is cut off and removed in the same manner. the core wires 102a of the branch twisted pair wire 102 and the core sires 101 a of the main twisted pair wire 101 are crimped by an intermediate joint terminal 103 so that the main twisted pair wire 101 is branch-connected with the brunch twisted pair wire 102.

In this case, a procedure in which the branch twisted pair wire branched from the main twisted pair wire will be explained below. First, a twist of the main twisted pair wire 101 to be connected is partially loosened at an intermediate position. Then, the insulating sheath in the loosened portion of the main twisted pair wire 101 is removed. The respective exposed core wires 101 a, 102a of the main twisted pair wire 101 and the branch twisted pair wire 102 are crimp-connected with each other by the intermediate joint terminal 103. Then an insulating tape (not shown) is wound round the connecting portion for insulation and protection. After that, the loosened twists of the twisted pair wires are back to a normal twisted state. In this way, the

connection is completed. This connection structure is disclosed, for example, in JP-A-2002-151169 (page 2, Fig. 15).

Next, Fig. 12 is a view showing a second related connection structure of twisted pair wires. In Fig. 12, a main twisted pair wire 101 for transmitting a signal from ECU 51 is connected with a branch twisted pair wire 102 for transmitting the signal to ECU 71 by the joint connector 104. In this connection structure, first of all, twist at the end portions of the main twisted pair wire 101 is loosened by a predetermined length L1 (for example, 80 to 100 mm), and then the insulating sheath at the end portions is removed. In the same manner, twist at the end portions of the branch twisted pair wire 102 is loosened by a predetermined length L1, and then the insulating sheath at the end portions is removed. The end portions of the main twisted pair wire 101 and the branch twisted pair wire 102 are electrically connected with each other by the joint connector 104. An adhesive tape 105 is wound round a boundary between the loosened portion of twist and the non loosened portion of twist in each of the main twisted pair wire 101 and the branch twisted pair wire 102.

Length L2 is a sum of the lengths L1 when the length of the loosened portion of the main twisted pair wire 101 and the length of the loosened portion of the branch twisted pair wire 102 are added to each other. The length L2 is twice as long as predetermined length L1, that is, length L2 is 160 to 200 mm.

Fig. 13 is a view showing a third related connection structure of twisted pair wires. In Fig. 13, the main twisted pair wire 101 for transmitting a signal from ECU 51 are connected with three sets of twisted pair wires 102 for respectively transmitting the signal to ECU 61,71, 81 by the joint connector 104. In the same manner as that of Fig. 12, in the case of this connecting

structure, twist at the end portions of the main twisted pair wire 101 is loosened by a predetermined length L1 (for example, 80 to 100 mm), and then the insulating sheath at the end portions is removed. In the same manner, twist at the end portions of the branch twisted pair wire 102 is loosened by a predetermined length L1, and then the insulating sheath at the end portion is removed. End portions of the main twisted pair wire 101 and the branch twisted pair wire 102 are electrically connected with each other by the joint connector 104. The adhesive tape 105 is wound round a boundary between the loosened portion of twist and the non loosened portion of twist in each of the main twisted pair wire 101 and the branch twisted pair wire 102.

However, in the above related connection structures of twisted pair wires, the following problems may be encountered. It is necessary to remove the insulating sheath from the twisted pair wires to be connected with the intermediate joint terminal and also to be connected with the joint connector.

Further, there is a possibility that moisture intrudes into the core wires from the intermediate joint terminal and the joint connector.

Further, the following problems may be encountered. A portion in which twist of the twisted pair wires are loosened (for example, shown in Figs.

12 and 13) is left as it is for the reasons of manufacture, and the effect of twist of the twisted pair wires can not be provided in the portion.

DISCLOSURE OF THE INVENTION It is therefore a first object of the present invention to provide a highly reliable connection structure of twisted pair wires which can be used without

being machined such as removing process of insulating sheaths of the twisted pair wires, and moisture intruding into the core wires of the twisted pair wires is prevented.

Also, a second object of the present invention is to provide an inexpensive and highly reliable near magnetic field non-contact communication device capable of realizing to send and receive communication data by using the connection structure of twisted pair wires of the present invention.

In order to achieve the above object, according to the present invention, there is provided a connection structure of twisted pair wires, comprising: a first twisted pair wire, having a first loop portion; a second twisted pair wire, having a second loop portion; and a fixing member, fixing the first loop portion and the second loop portion in a state that the first loop portion and the second loop portion are disposed close to each other, wherein an electromagnetic induction coupling is generated between the first loop portion and the second loop portion when a signal flows in the first twisted pair wire, so that the signal is transmitted from the first twisted pair wire to the second twisted pair wire in a state of non-contact.

In the above configuration, in the connection structure of twisted pair wires, a portion of the first twisted pair wire is expanded to form the first loop portion, and a portion of the second twisted pair wires is expanded to form the second loop portion, and the first and the second loop portions are made to come close to each other and fixed by the fixing member. Due to the above structure, when a signal flows in the first twisted pair wires, an electromagnetic

induction coupling is generated between the first and the second loop portions.

Therefore, the signal is transmitted from the first twisted pair wire to the second twisted pair wire in a state of non-contact. Accordingly, it is possible to realize a highly reliable connection structure of twisted pair wires which can be used without being machined, in which there is no possibility that moisture gets into the core wires.

Preferably, a diameter of the first loop portion is substantially identical to a diameter of the second loop portion.

In the above configuration, a diameter of the first loop portion and a diameter of the second loop portion are formed being substantially equal to each other. Therefore, the fixing work can be easily performed and the working property can be enhanced.

Preferably, the fixing member is an adhesive tape.

In the above configuration, the manufacturing cost can be reduced.

Preferably, the fixing member is a coil bobbin.

In the above configuration, the fixing work can be easily performed and the working property can be enhanced.

According to the present invention, there is also provided near magnetic field non-contact communication device using the connection structure of twisted pair wires, comprising: a first communicator, having the first twisted pair wire in which the first loop portion thereof is used as a first antenna; and a second communicator, having the second twisted pair wire in which the second loop portion thereof is used as a second antenna, wherein data is communicated between the first communicator and

the second communicator through the electromagnetic induction coupling generated between the first loop portion and the second loop portion.

In the above configuration, it is possible to realize to send and receive communication data with high reliability at low cost.

Preferably, the first communicator include a first transformer adjusting impedance. The second communicator include a second transformer adjusting impedance.

In the above configuration, it is possible to enhance the receiving efficiency and realize an electromagnetic coupling communication conducted by a weak signal.

Preferably, the first transformer is connected to the first antenna.

The second transformer is connected to the second antenna.

Preferably, the first communicator is a master ECU and the second communicator is a slave ECU.

In the above configuration, it is possible to realize an electromagnetic coupling communication conducted by a weak signal in the master-slave communication system.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing the connection structure of the twisted pair wires according to a first embodiment of the present invention.

Fig. 2 is a view showing the connection structure of the twisted pair wires according the second embodiment of the present invention.

Fig. 3 is a view showing the structure of the near magnetic field

non-contact communication device according the third embodiment of the present invention.

Fig. 4 is a block diagram showing the structure of master ECU in the near magnetic field non-contact communication device shown in Fig. 3.

Fig. 5 is a block diagram showing the structure of slave ECU in the near magnetic field non-contact communication device shown in Fig. 3.

Fig. 6 is a signal wave-form diagram of each portion in the near magnetic field non-contact communication device shown in Fig. 3.

Fig. 7 is a partial circuit diagram showing the near magnetic field non-contact communication device according the fourth embodiment of the present invention.

Fig. 8 is a view showing the near magnetic field non-contact communication device according the fifth embodiment of the present invention.

Fig. 9 is a view showing the near magnetic field non-contact communication device according the sixth embodiment of the present invention.

Fig. 10 is a view showing the related electric connection structure between ECUs.

Fig. 11 is a view showing the first related the connection structure of twisted pair wires.

Fig. 12 is a view showing the second related connection structure of twisted pair wires.

Fig. 13 is a view showing the third related connection structure of twisted pair wires.

BEST MODE FOR CARRYING OUT THE INVENTION Referring to the drawings, embodiments of the present invention will be explained below.

Fig. 1 is a view showing the connection structure of the twisted pair wires according to the first embodiment of the present invention. In the connection structure of the twisted pair wires, a loop-shaped portion la as a first loop-shaped portion is formed in a portion of a main twisted pair wire 1.

Also, a loop-shaped portion 2a as a second loop-shaped portion is formed in a portion of the branch twisted pair wire 2. The loop-shaped portion 1 a and the loop-shaped portion 2a are positioned so as to close to each other and fixed with the adhesive tape 3 as a fixing member. Due to this structure, the main twisted pair wire 1 and the branch twisted pair wire 2 are connected with each other by the electromagnetic induction coupling in a state of non-contact in physically.

A procedure of this connecting work will be explained below. First, at an arbitrary point on the main twisted pair wire 1, twist of the wire is expanded into a loop-shape to form the loop-shaped portion 1a, the diameter of which is a predetermined value (for example, 20 to 30 mm). Next, twist of a portion of the branch twisted pair wire 2, for example, twist of a forward end portion of the branch twisted pair wire 2 is expanded into a loop-shape to form the loop-shaped portion 2a, the diameter of which is substantially the same as that of the loop-shaped portion 1a. Next, the loop-shaped portion 1 a and the loop-shaped portion 2a are positioned so as to close to each other by stacking the loop-shaped portions 1a, 2a. Then, several portions (two portions in the

case shown in Fig. 1) of the loop-shaped portion 1 a and those of the loop-shaped portion 2a are fixed to each other with the adhesive tape 3.

Due to the above structure, when a signal flows through the main twisted pair wire 1, electromagnetic induction coupling portion EMC for generating an electromagnetic induction coupling between the loop-shaped portion 1a and the loop-shaped portion 2a can be formed. Therefore, the signal flowing through the main twisted pair wire 1 is transmitted from the loop-shaped portion 1a to the loop-shaped portion 2a of the branch twisted pair wire 2 by the electromagnetic induction coupling.

As described above, according to the first embodiment, when the loop-shaped portion 1a of the main twisted pair wire 1 and the loop-shaped portion 2a of the branch twisted pair wire 2 are made to come close to each other and fixed by the adhesive tape 3, the main twisted pair wire 1 and the branch twisted pair wire 2 are connected with each other in a state of non-contact by the electromagnetic induction coupling between the loop-shaped portions 1a, 2a. Accordingly, it is possible to realize a highly reliable connection structure of twisted pair wires at a low manufacturing cost which can be used without being machined, and further there is no possibility that moisture intrudes into the core wires from the calked portion or the connecting portion. Since the diameter of the loop-shaped portion 1a and that of the loop-shaped portion 2a are substantially the same, the fixing work can be easily performed and the working property can be enhanced. Since the fixing member is composed of an adhesive tape, the manufacturing cost can be reduced.

Fig. 2 is a view showing the connection structure of the twisted pair

wires according to a second embodiment of the present invention. In the connection structure shown in Fig. 2, the loop-shaped portion 1 a is formed in a portion of the main twisted pair wire 1, and the loop-shaped portion 2a is formed in a portion of the branch twisted pair wire 2. The loop-shaped portion 1a and the loop-shaped portion 2a are wound round the bobbin coil 4 as a fixing member so as to be close to each other. Due to this structure, the main twisted pair wire 1 and the branch twisted pair wire 2 are connected with each other by the electromagnetic induction coupling in a state of non-contact. The coil bobbin 4 has two winding portions 4a, 4b, which are arranged on both sides of the intermediate partition 4c, the diameters of which are predetermined (for example, 20 to 30 mm). The loop-shaped portion 1a is wound round the winding portion 4a, and the loop-shaped portion 2a is wound round the winding portion 4b.

A procedure of this connecting work will be explained below. First, at the forward end portion of the main twisted pair wire 1, twist is expanded into a loop shape to form the loop-shaped portion 1a. Next, the coil bobbin 4 is prepared, and the loop-shaped portion 1a is fixed to the winding portion 4a of the coil bobbin 4. Next, at the forward end portion of the branch twisted pair wire 2, twist is expanded into a loop shape to form the loop-shaped portion 2a. Next, the loop-shaped portion 2a is fixed to the winding portion 4b of the coil bobbin 4.

In the structure described above, the loop-shaped portion 1a of the main twisted pair wire 1 and the loop-shaped portion 2a of the branch twisted pair wire 2 are positioned so as to be close to each other and fixed by the coil bobbin 4. When a signal flows through the main twisted pair wire 1, an

electromagnetic induction coupling portion EMC for generating an electromagnetic induction coupling between the loop-shaped portion 1a and the loop-shaped portion 2a can be formed. Therefore, the signal flowing through the main twisted pair wire 1 is transmitted from the loop-shaped portion 1a to the loop-shaped portion 2a of the branch twisted pair wire 2 by the electromagnetic induction coupling described above.

As described above, according to the second embodiment, when the loop-shaped portion 1 a of the main twisted pair wire 1 and the loop-shaped portion 2a of the branch twisted pair wire 2 are positioned so as to be close to each other and fixed by the coil bobbin 4, the main twisted pair wire 1 and the branch twisted pair wire 2 are connected with each other in a state of non-contact by the electromagnetic induction coupling between the loop-shaped portions 1a, 2a. Accordingly, it is possible to realize a highly reliable connection structure of twisted pair wires at a low manufacturing cost which can be used without being machined, and further there is no possibility that moisture gets into the core wires. Since the fixing member is a coil bobbin, the fixing work can be easily performed and the working property can be enhanced.

Next, referring to Fig. 3, explanations will be made into the structure of the near magnetic field non-contact communication device according to a third embodiment of the present invention. The near magnetic field non-contact communication device is used in the connection structure of the twisted pair wires of the present invention. As shown in Fig. 3, in the near magnetic field non-contact communication device, the master-slave communication between master ECU 31 as a first correspondence unit, and a

plurality of slave ECUs as second correspondence units, for example, three slave ECUs 41 a, 41 b, 41 c, is conducted while the connection structure of the main twisted pair wire 1 and the branch twisted pair wire 2 is being used as an antenna.

Master ECU 31 is connected with the main twisted pair wire 1 having two loop-shaped portion 1a at the intermediate portions thereof and one loop-shaped portion 1a at the forward end portion thereof. Slave ECUs 41 a, 41 b, 41 c are respectively connected with the branch twisted pair wires 2 having the loop-shaped portions 2a at the forward end portions thereof respectively. In each loop-shaped portion 1a and loop-shaped portion 2a, electromagnetic induction coupling portion EMC for generating an electromagnetic induction coupling is formed by the connection structure of twisted pair wires shown in Figs. 1 and 2.

Next, Fig. 4 is a block diagram showing the structure of master ECU 31 shown in Fig. 3. The master ECU 31 includes a data communication circuit 33 and a microcomputer (CPU) 34. The data communication circuit 33 is supplied an electric power from a battery of +12 V. The data communication circuit 33 is connected with the main twisted pair wire 1 having the loop-shaped portion 1a. The main twisted pair wire 1 is used as an antenna. The data communication circuit 33 includes a sending portion 33A and a receiving portion 33B which are controlled by CPU 34 so that master-slave communication can be performed. CPU 34 is connected with an indicator 36 including various types of switches 35 and LED (light emitting diodes).

The data communication circuit 33 includes a sending portion 33A, a

receiving portion 33B and a power supply portion 33C. The sending portion 33A includes a modulation circuit 33a, a wave-form shaping filter 33b, a sending driver 33c and a control portion 33d. The modulation circuit 33a ON-OFF modulates the sending data (Tx) supplied from CPU 34 based on a clock pulse (for example, 125 kHz) supplied from CPU 34 while the clock pulse is used as a base signal. The wave-form shaping filter 33b shapes a wave-form of the modulated wave pulse sent from the modulation circuit 33a to a sine wave. The sending driver 33c drives the twisted pair wires 1 when an output of the wave-form shaping filter 33b is supplied. The control portion 33d controls the data communication circuit 33 according to sending-receiving switching signal TRch sent from CPU 34 so that the data communication circuit 33 is switched between the sending permission state and the receiving permission state. The control portion 33d also controls the data communication circuit 33 according to the electric power control signal (Pcnt) sent from CPU 34 so that the data communication circuit 33 is switched to a low electric power consumption mode.

The receiving portion 33B includes a tuning circuit 33e and a demodulation circuit 33f. The tuning circuit 33e is connected with the twisted pair wire 1, and tunes with the clock pulse frequency (125 kHz) of CPU 34.

The demodulation circuit 33f demodulates an output of the tuning circuit 33e so as to obtain data, and supplies the data to CPU 34.

The electric power supply 33C connects with a battery of +12 V and supplies an appropriate power source voltage to each portion of the data communication circuit 33 and further supplies an electric power supply voltage of +5 V to CPU 34.

Next, Fig. 5 is a block diagram showing the constitution of slave ECU 41 a. Slave ECU 41 a includes a data communication circuit 43 and a micro computer (CPU) 44. The data communication circuit 43 is supplied electric power from the battery of +12 V. The data communication circuit 43 is connected with the branch twisted pair wire 2 having the loop-shaped portion 2a. The branch twisted pair wire 2 is used as an antenna. The data communication circuit 43 includes a sending portion 43A and a receiving portion 43B which are controlled by CPU 44 so that master-slave communication can be performed. CPU 44 is connected with an indicator 46 having various switches 45 and LED (light emitting diodes).

The data communication circuit 43 includes a sending portion 43A a receiving portion 43B and an electric power supply portion 43C. The sending portion 43A includes a modulation circuit 43a, a wave-form shaping filter 43b, a sending driver 43c and a control portion 43d. The modulation circuit 43a ON-OFF modulates the sending data (Tx) supplied from CPU 44 based on a clock pulse (for example, 125 kHz) supplied from CPU 44 while the clock pulse is used as a base signal. The wave-form shaping filter 43b shapes a wave-form of the modulated wave pulse sent from the modulation circuit 43a to a sine wave. The sending driver 43c drives the branch twisted pair wires 2 when an output of the wave-form shaping filter 43b is supplied. The control portion 43d controls the data communication circuit 43 according to sending-receiving switching signal TRch sent from CPU 44 so that the data communication circuit 43 is switched between the sending permission state and the receiving permission state. The control portion 43d also controls the data communication circuit 43 according to the electric power control signal

(Pcnt) sent from CPU 44 so that the data communication circuit 43 is switched to a low electric power consumption mode.

The receiving portion 43B includes a tuning circuit 43e connected with the branch twisted pair wire 2, tuning with the clock pulse frequency (125 kHz) of CPU 44, and a demodulating circuit 43f for demodulating an output of the tuning circuit 43e and acquiring data in the system of the serial correspondence so as to supply the data to CPU 44.

The electric power supply portion 43C connects with a battery of +12 V and supplies an appropriate electric power source voltage to each portion of the data communication circuit 43 and further supplies an electric power supply voltage of +5 V to CPU 44.

In this connection, the structures of slave ECUs 41 b, 41 c are the same as that of slave ECU 41 a described above. Therefore, the explanations are omitted here.

Next, referring to the signal wave-form diagram shown in Fig. 6, behavior of master ECU 31 and slave ECUs 41 a, 41 b, 41 c will be explained below.

As illustrated in Fig. 6, master ECU 31 and slave ECUs 41 a, 41 b, 41 c operate as follows. When master ECU 31 is set in the sending permission state by sending-receiving switching signal TRch, the slave ECUs 41 a, 41 b, 41 c are set in the receiving permission state. When slave ECUs 41 a, 41 b, 41 c are set in the sending permission state, the master ECU 31 is set in the receiving permission state. In this way, sending and receiving can be alternately conducted.

When data is sent from the master ECU 31 to the slave ECUs 41 a,

41 b, 41 c, CPU 34 of the master ECU 31 supplies a clock pulse of 125 kHz to the modulation circuit 33a in the case of the sending permission state by sending-receiving switching signal TRch, and also CPU 34 of the master ECU 31 receives data which is based on the direction signal supplied from various switches 35, in the serial communication system to supply the data to the modulation circuit 33a as sending data (Tx). The modulation circuit 33a conducts ON-OFF modulation on the sending data while the clock pulse of 125 kHz is used as a base signal. The pulse output of the wave to be modulated is supplied to the wave-form shaping filter 33b. The wave-form shaping filter 33b shapes the wave-form of the pulse output of the modulated wave, and supplies a sine-wave-shaped output of the modulated wave to the sending driver 33c. The sending driver 33c amplifies the sine-wave-shaped output of the modulated wave sent from the wave-form shaping filter 33b and supplies the amplified output to the main twisted pair wire 1 so as to drive the loop-shaped portion 1a.

When the master ECU 31 is in the sending permission state, the slave ECU 41 a is in the receiving permission state. Therefore, a sine-wave-shaped modulated wave is transmitted from the loop-shaped portion 1 a to the loop-shaped portion 2a of the branch twisted pair wire 2 of the slave ECU 41 a by the electromagnetic induction coupling. The sine-wave-shaped modulated wave transmitted to the loop-shaped portion 2a is demodulated by the demodulation circuit 43f via the tuning circuit 43e, and data (Rx (= Tx)) is acquired and supplied to CPU 44. According to the content of the data (Rx) supplied, CPU 44 controls various switches 45 and turns on the corresponding indicator 46.

Next, the master ECU 31 is set in the receiving permission state by sending and receiving switching signal TRch, and the slave ECU 41 a is set in the sending permission state by the sending and receiving switching signal TRch. In the sending permission state permitted by the sending and receiving switching signal TRch, CPU 44 of the slave ECU 41 a supplies a clock pulse of 125 kHz to the modulation circuit 33a and receives data, which is based on the direction signal supplied from various switches 45, in the system of serial communication and supplies the data to the modulation circuit 43a as sending data (Tx). While the clock pulse of 125 kHz is used as a base signal, the modulation circuit 43a conducts ON-OFF modulation on the sending data and supplies an output of the pulse of the modulated wave to the wave-form shaping filter 33b. The wave-form shaping filter 33b shapes a wave-form of the output of the pulse of the modulated wave and supplies an output of the sine-wave-shaped modulated wave to the sending driver 33c. The sending driver 33c amplifies the output of the sine-wave-shaped modulated wave sent from the wave-form shaping filter 33b and supplies it to the main twisted pair wire 1 to drive the loop-shaped portion 2a.

The sine-wave-shaped modulated wave is transmitted from the loop-shaped portion 2a to the loop-shaped portion 1a of the main twisted pair wire 1 of the master ECU 31 by the electromagnetic induction coupling action in electromagnetic induction coupling portion EMC. The sine-wave-shaped modulated wave transmitted to the loop-shaped portion 1a is demodulated by the demodulation circuit 33f through the tuning circuit 33e, and data (Rx (= Tx)) is acquired and supplied to CPU 34. According to the content of the data (Rx) supplied, CPU 34 controls various switches 35 and turns on the corresponding

indicator 36.

Next, the master ECU 31 is set in the sending permission state again by the sending and receiving switching signal TRch. At this time, the slave ECU 41 b is set in the receiving permission state by the sending and receiving switching signal TRch. In the same manner as that of the slave ECU 41 a, the slave ECU 41 b receives data sent from the master ECU 31, via the electromagnetic induction coupling of the loop-shaped portion 1a and the loop-shaped portion 2a. Next, the master ECU 31 is set in the receiving permission state again by the sending and receiving switching signal TRch, and the slave ECU 41 b is set in the sending permission state by the sending and receiving switching signal TRch. In the same manner as that of the slave ECU 41 a, the slave ECU 41 b sends data to the master ECU 31 via the electromagnetic induction coupling of the loop-shaped portion 1 a and the loop-shaped portion 2a.

Next, the master ECU 31 is set again in a sending permission state by the sending and receiving switching signal TRch, and the slave ECU 41 c is set in a receiving permission state by the sending and receiving switching signal TRch. In the same manner as that of the slave ECU 41 b, the slave ECU 41 c receives data sent from the master ECU 31 via the electromagnetic induction coupling of the loop-shaped portion 1a and the loop-shaped portion 2a. Next, the master ECU 31 is switched to the receiving permission state, and the slave ECU 41 c is switched to the sending permission state, and data sent from the slave ECU 41 c is sent to the master ECU 31 via the electromagnetic coupling of the loop-shaped portion 1a and the loop-shaped portion 2a.

Sending and receiving of data between the master ECU 31 and the slave ECUs 41 a, 41 b, 41 c are conducted by the master-slave communication system in the order described above.

As described above, in the near magnetic field non-contact communication device, the master ECU 31 in which the antenna is formed by the loop-shaped portion 1 a of the main twisted pair wire 1, and the slave ECUs 41 a, 41 b, 41 c in which each antenna is formed by the loop-shaped portion 2a of the branch twisted pair wire 2. Data is sent and received by the electromagnetic induction coupling between the loop-shaped portion 1a and the loop-shaped portions 2a. Therefore, in the master-slave communication system, a signal can be simply made to branch and sent from the correspondence line of the master ECU to each slave ECU by the electromagnetic coupling communication with a weak signal. Accordingly, communication data can be highly reliably sent and received at low cost.

In the case of near magnetic field non-contact communication in which electromagnetic induction coupling is used, the antenna is very important. It is necessary to conduct matching of the antenna with the communication circuit, and the antenna must be positively fixed at a position close to the opponent correspondence ECU antenna so that the antenna and the opponent correspondence ECU antenna can be opposed to each other, that is, it is necessary to maintain a predetermined positional relation between the antenna and the opponent correspondence ECU antenna. Unless these conditions are satisfied, it becomes impossible to realize communication and enhance reliability of the communication technique in which consideration is given to a method of fixing the antenna and a positional shift of the antenna

from the opponent antenna. When the connection structure of the twisted pair wires shown in Fig. 1 or 2 is used, the above near magnetic field non-contact communication device can overcome the above problems and a highly reliable near magnetic field non-contact communication can be performed.

Embodiments of the present invention are explained above.

However, it should be noted that the present invention is not limited to the above specific embodiments, and various modifications and applications can be made without departing from the spirit and scope of the invention.

For example, when the twist pair wires are used as an antenna, the antenna impedance is greatly lowered. Therefore, as shown in the fourth embodiment shown in Fig. 7, on both sides of the master ECU 31 and the slave ECU 41 a (41 b, 41 c), small transformers IRT used for adjusting impedance may be connected between the main twisted pair wire 1 and the data communication circuit 33 and also between the branch twisted pair wire 2 and the data communication circuit 43.

In these transformers IRT used for adjusting impedance, for example, a ratio of the number of windings on the side connected with the data communication circuit 33 to the number of windings on the side connected with the twisted pair wires 1,2 is set at 4: 1. Therefore, the impedance is increased higher than the impedance in the case where the twisted pair wires 1,2 are directly connected with the data communication circuits 33,43.

Therefore, the receiving efficiency of the receiving portions 33B, 43B in the data communication circuits 33,43 can be improved higher than that of the circuit structure shown in Figs. 4 and 5. Accordingly, it is possible to realize

an electromagnetic coupling communication with a weak signal.

Further, as the fifth embodiment, it is possible to adopt the following structure. As shown in Fig. 8, electric power is supplied among ECUs 51,61, 71,81 by the electric power supply line 110 composed of the wire harness, and signals are transmitted via electromagnetic induction coupling portion EMC of the main twisted pair wire 1 and the branch twisted pair wire 2.

Further, as the sixth embodiment, the following structure may be adopted. As shown in Fig. 9, in the case of supplying electric power from a battery (not shown) to the equipment arranged on the instrument panel 93 of a vehicle and transmitting a signal to the equipment, electric power is supplied by the electric power supply line 110 via the junction box (J/B) 92 for electric power supply use, and signal transmission is conducted via electromagnetic induction coupling portion EMC of the main twisted pair wire 1 and the branch twisted pair wire 2.

In the structure shown in Fig. 9, electric power is supplied from the vehicle body side to the instrument panel 91 side via J/B 92, however, signals are transmitted from the vehicle body side to the instrument panel 91 side via not J/B 92 but electromagnetic induction coupling portion EMC of the main twisted pair wire 1 and the branch twisted pair wire 2. Further, signals are transmitted to the navigation device 91, which is arranged on the left of the steering wheel 94 on the instrument panel 92, via electromagnetic induction coupling portion EMC of the main twisted pair wire 1 and the branch twisted pair wire 2.

INDUSTRIAL APPLICABILITY

In view of the above, a highly reliable connection structure of twisted pair wires which can be used without being machined such as removing process of insulating sheaths of the twisted pair wires is obtained. Also, the connection structure of twisted pair wires in which moisture intruding into the core wires of the twisted pair wires is prevented is obtained.

Further, an inexpensive and highly reliable near magnetic field non-contact communication device capable of realizing to send and receive communication data used in the connection structure of twisted pair wires is obtained.