JP3977830B2 - Electric field communication transmitter - Google Patents

Description

  The present invention relates to an electric field communication transmitter that induces an electric field in an electric field transmission medium and transmits information using the induced electric field.

  Due to the miniaturization and high performance of portable terminals, wearable computers that can be attached to a living body have attracted attention. Conventionally, as information communication between such wearable computers, a transceiver including an electric field communication transmitter is connected to a computer, and an electric field induced by the transceiver is transmitted to the inside of a living body which is an electric field transmission medium. A method for transmitting and receiving information has been proposed (see, for example, Patent Document 1).

  For example, as shown in FIG. 10, the structure of the transceiver 110 includes a stray capacitance Cb127 between the ground ground 113 and a stray capacitance Cg128, a variable reactance unit 118 for causing a resonance phenomenon, and information to be transmitted on a carrier wave. A transmission circuit 115 for modulating and outputting the signal, a transmission / reception electrode 116 for inducing an electric field as a signal in the human body 112 and detecting the induced electric field, and insulating between the transmission / reception electrode 116 and the human body 112 And an insulator 117.

  Furthermore, when controlling the electric field detecting optical unit 125 for detecting the electric field and converting it into an electric signal, the signal processing unit 124, the switch 123 for changing connection between transmission and reception, and the variable reactance unit 118, the human body 112 is controlled. And an amplitude monitor unit 121 for monitoring the electric field amplitude induced by.

  Also, a control signal generator 122 for generating a signal for controlling the variable reactance unit 118 based on the signal of the amplitude monitor unit 121, a demodulation circuit 120 for demodulating the received signal and reproducing information, and a reproduction A waveform shaping unit 119 for adjusting the waveform of the information, and an I / O circuit 114 for transmitting and receiving information between the terminal 111 and the transceiver 110.

  Examples of applications that make use of the technology relating to the above-mentioned electric field communication transmitter include, for example, payment of charges at transportation facilities and ID cards for security.

  For example, as shown in FIG. 9, such a technique includes a transmitter 101 for transmitting unique information such as an ID, a sheet 105 installed on the ground 106 for detecting information via the human body 100, A computer 103 that opens and closes the gate 102 by comparing a signal from the receiver 104 with information registered in advance, a receiver 104 that outputs the detected signal to the computer 103, and a gate that controls the entry and exit of the human body 100 102.

  Conventionally, a non-contact IC card using near field communication technology has been used as an ID card.

  For these ID cards that need to be taken out in front of the ticket gate of a train or in a room door, an electric field communication transmitter is used that induces an electric field on an object or a human body and communicates by detecting the induced electric field. , You can go through the ticket gate and door without having to take out the card.

  Also, in an electric field communication transceiver that floats from the earth ground, a variable reactance is inserted between the transmitting and receiving electrodes and the transmitter circuit to efficiently induce an electric field in the human body, and resonance of stray capacitance between the human body and circuit ground and the earth ground The phenomenon is used.

Conventionally, in order to maintain the resonance phenomenon in accordance with the floating stray capacitance, the electric field induced by the person is monitored to control the reactance value of the variable reactance unit.
JP 2001-352298 A JP 2004-153708 A

  In the above-described conventional electric field communication transmitter, the method of appropriately controlling the variable reactance unit, which requires a part of the receiving unit, has a large circuit scale and it is difficult to reduce the size of the transmitter.

  The present invention has been made in view of the above-described problems, and the object of the present invention is to cope with a floating capacitance that varies by changing a reactance value in a transmitter for transmitting a signal such as information. An object of the present invention is to provide an electric field communication transmitter capable of reducing the circuit scale.

  In order to solve the problem, the present invention according to claim 1 is an electric field communication transmitter that induces an electric field in an electric field transmission medium and transmits information using the induced electric field, and stores the information. Information storage means, transmission means for modulating the information output from the information storage means with a carrier wave, and transmission voltage applied to the electric field transmission medium is maximized Variable reactance means for controlling the resonant state between the stray capacitance between the transmitter ground and the ground ground and the stray capacitance between the electric field transmission medium and the ground ground by changing the reactance value, and the reactance value in the variable reactance means And transmitter control means for controlling the information output from the information storage means.

  According to a second aspect of the present invention, there is provided an electric field communication transmitter for inducing an electric field in an electric field transmission medium and transmitting information using the induced electric field, wherein the information storage stores the information. And the information output from the information storage means are modulated with a carrier wave, and the frequency of the carrier wave is changed so that the voltage of the transmission applied to the electric field transmission medium becomes maximum, and the resonance is controlled and transmitted. Transmitting means for performing, reactance means for inducing the electric field in the electric field transmission medium having a fixed reactance value, control of the frequency of the carrier wave in the transmitting means, and the information output by the information storage means Transmitter control means for performing the above control.

  According to a third aspect of the present invention, there is provided an electric field communication transmitter for inducing an electric field in an electric field transmission medium and transmitting information using the induced electric field, wherein the information storage stores the information. Means for transmitting the information output from the information storage means simultaneously with a plurality of carrier waves, and reactance means for inducing the electric field in the electric field transmission medium having a fixed reactance value And transmitter control means for controlling the information output by the information storage means.

  According to a fourth aspect of the present invention, in the third aspect, the transmission means includes a wide-band AC signal source for generating and transmitting a plurality of the carrier waves.

  According to the present invention, in an oscillator for transmitting a signal such as information, an electric field communication oscillator that can cope with a stray capacitance that varies by transmitting while changing a reactance value and can be reduced in circuit scale. Can be provided.

<First Embodiment>
FIG. 1 shows an overall configuration diagram according to the first embodiment of the electric field communication transmitter of the present invention.

  The transmitter 1 which is an electric field communication transmitter according to the present embodiment includes a transmission circuit 5 for modulating and outputting information with a carrier wave, and an information storage unit 6 for storing fixed information and outputting it to the transmission circuit 5. A transmitter control unit 7 for setting a reactance value of the variable reactance unit 4 and outputting a signal for outputting information to the information storage unit 6, and a transmission electrode 8 connected to the variable reactance unit 4 for transmitting information , And is configured.

The transmitter electrode 8 provided in the transmitter 1 is in contact with the human body 2 via the insulator 9. In addition, the human body 2 has a potential _Vb with the ground 3.

Next, the operation of the transmitter 1 according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 2 shows a timing chart of reactance value control according to the first embodiment of the electric field communication transmitter of the present invention. FIG. 3 is a diagram for explaining the reactance value dependency of the voltage _{Vb according} to the first embodiment of the electric field communication transmitter of the present invention. FIG. 4 shows a flowchart for explaining the operation according to the first embodiment of the electric field communication transmitter of the present invention.

  The transmitter 1 transmits information such as ID data, which is fixed information, from the transmitter control unit 7 at regular intervals W. The transmission of this information is executed by changing the reactance value as shown in the reactance value timing chart 10 referred to in FIG.

  Here, the reactance value is divided into stages, and in the reactance value timing chart 10, the fixed information is transmitted five times. In addition, the reactance value that is executed in the variable reactance unit 4 is variably controlled in accordance with a control signal output from the transmitter control unit 7.

By performing transmission while varying the reactance value, as shown in FIG. 2 and FIG. 3, the voltage V _b between the human body 2 and the ground 3 is the third time as shown in the V _b value timing chart 11. The reactance value (corresponding to the reactance value at the timing (3) shown in the reactance value timing chart 10) indicates the maximum value.

Note that the relationship between the reactance value and the voltage V _{b is} the relationship between the V _b value / reactance value shown in FIG. 3 and (3) the value of the reactance value at the third time, the amplitude of the voltage V _b is the maximum value due to resonance. It becomes. That is, the variable reactance section 4 of the transmitter 1, the voltage V _b applied to the human body 2 if it becomes certain reactance value (e.g. the reactance value illustrated in FIG. 2 (3)) is maximized.

  Here, if it demonstrates with reference to FIG. 4, the setting of the reactance value is performed in the reactance part 4 in step S1. This reactance value is determined based on a setting signal from the transmitter controller 7.

  Next, in step S2, information output is executed. In this information output, fixed information such as ID data stored in the information storage unit 6 is sent to the variable reactance unit 4 via the transmission circuit 5 and finally to the human body 2 via the transmission electrode 8. The output to reach. Information output is executed by an information output command output from the transmitter controller 7.

  Next, in step S3, it is determined whether or not the next set value of the variable reactance is within the variable range. This determination is made by the transmitter control unit 7 in consideration of the range of reactance values that can be varied by the variable reactance unit 4 and the range of set values of reactance values that can be controlled by the transmitter control unit 7.

  If it is determined in step S3 that the next set value of the current reactance value is within the variable range, the process returns to step S1 and variable reactance is set.

  If it is determined in step S3 that the next set value of the current reactance value is outside the variable range, the change of the reactance value ends.

  Next, in step S4, the reactance value is reset to the initial value after the change of the reactance value goes through the settable range.

  Next, in step S5, a standby state (time W wait) is entered during time W. When this standby is completed, the operation is repeated from step S1.

As described above, the reactance value at which resonance occurs varies depending on the circuit ground and the stray capacitance between the human body 2 and the ground 3. Therefore, the change range of the reactance value is set within a variable range, and within this range, a large signal (voltage V _b ) can be applied with the set reactance value.

  In the case of the transmitter 1 applied to a system that only needs to receive the fixed information once, it is not limited to a method in which the reactance value is reliably adjusted and sequentially transmitted. For example, some values in which the reactance value is set in advance are used. Communication is possible even if the fixed information is transmitted after sequentially changing to.

  In this case, since the circuit scale of the transmitter 1 can be reduced, it is possible to cope with the floating capacitance that varies by changing the reactance value, and the entire electric field communication transmitter can be downsized.

  In the first embodiment, the time interval for sequentially changing the reactance value is set to 0 seconds, but this time interval may be arbitrarily set. The order of changing the reactance value is not limited to small to large, but may be reversed or random. Further, the power consumption can be reduced by turning off the power supply of the transmission circuit 5 and the like during the non-transmission time.

<Second Embodiment>
FIG. 5 shows a schematic overall configuration according to the second embodiment of the electric field communication transmitter of the present invention.

  A transmitter 1 shown in FIG. 5 is a second embodiment of the electric field communication transmitter according to the present invention. As a configuration, the transmitter 1 is based on a reactance unit 13 for causing a stray capacitance and a resonance phenomenon, and a setting signal. A transmission circuit 5 for setting a frequency of a carrier wave to be output, modulating and outputting information to be transmitted with the carrier wave, a transmission electrode 8 for inducing an electric field as a signal in the human body, an insulator 9, and a transmission object An information storage unit 6 that stores information and outputs it to the transmission circuit 5, and a transmitter control unit 7 that controls the information storage unit 6 and the transmission circuit 5 are provided.

  The transmitter 1 having such a configuration is provided with a reactance unit 13 instead of the variable reactance unit 4 as compared with the configuration of the first embodiment of the present invention (see FIG. 1) already described. 7 differs in that it is connected to the transmission circuit 5 to provide a setting signal.

  The reactance value set in the reactance unit 13 is not variable but indicates a fixed value. On the other hand, the carrier wave transmitted by the transmission circuit 5 transmits the fixed information in the information storage unit 6 by sequentially changing the frequency of the carrier wave in the transmission circuit 5 to several preset values.

The frequency of the carrier wave transmitted from the transmission circuit 5 is changed in chronological order according to, for example, five types of frequencies (reactance values in the figure are read as frequencies) as shown in FIG. Since the frequency of the carrier wave changes, the voltage _Vb shows the maximum value when the resonance frequency and the carrier wave frequency are matched or close to each other due to the relationship between the reactance value of the reactance unit 13 and the stray capacitance.

<Third Embodiment>
FIG. 6 shows a schematic overall configuration according to the third embodiment of the electric field communication transmitter of the present invention.

  A transmitter 1 shown in FIG. 6 is a third embodiment of the electric field communication transmitter according to the present invention. As a configuration thereof, a reactance unit 13 for causing a stray capacitance and a resonance phenomenon, and a carrier wave having a broadband frequency are provided. A broadband AC signal source 17 for output, a modulation circuit 16 and a transmission circuit 15 for setting the frequency of a carrier to be output based on a setting signal, modulating and outputting information to be transmitted with the carrier, and a human body A transmission electrode 8 for inducing an electric field as a signal, an insulator 9, an information storage unit 6 for storing information to be transmitted and outputting it to the transmission circuit 5, and a transmitter for controlling the information storage unit 6 And a control unit 7.

  In the transmitter 1 having such a configuration, the transmitter control unit 7 controls only the information storage unit 6 as compared with the configuration of the second embodiment of the present invention described above (see FIG. 5). The transmission circuit 15 is different in that a modulation circuit 16 and a broadband AC signal source 17 are provided.

  In the transmitter 1 according to the third embodiment, as shown in FIG. 7, a carrier wave composed of a wideband frequency is output at a time. Since the transmitted carrier wave has a wide band, there is a frequency at which resonance occurs in this band. For example, resonance occurs at a resonance frequency indicated by an arrow in FIG.

  Due to this resonance, as shown in FIG. 8, a frequency component close to the resonance frequency is largely applied to the human body. In this way, a resonance phenomenon can be caused by only one transmission, and a large signal can be applied to the human body, so that it is not necessary to sequentially change the frequency of the carrier wave, and transmission control can be simplified.

1 is a schematic overall configuration diagram according to a first embodiment of an electric field communication transmitter of the present invention. The timing chart of the reactance value control based on 1st Embodiment of the electric field communication transmitter of this invention is shown. The figure for demonstrating the reactance value dependence of the voltage _{Vb based} on 1st Embodiment of the electric field communication transmitter of this invention is shown. The flowchart for demonstrating operation | movement based on 1st Embodiment of the electric field communication transmitter of this invention is shown. The schematic whole structure based on 2nd Embodiment of the electric field communication transmitter of this invention is shown. The schematic whole structure based on 3rd Embodiment of the electric field communication transmitter of this invention is shown. The figure for demonstrating the output of the broadband alternating current signal source based on 3rd Embodiment of the electric field communication transmitter of this invention is shown. The figure for demonstrating the output of the broadband alternating current signal source based on 3rd Embodiment of the electric field communication transmitter of this invention is shown. The schematic block diagram of the electric field communication transmitter by a prior art is shown. An explanatory view for explaining operation of transmission and reception of a transceiver by conventional technology is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmitter 2 Human body 3 Earth ground 4 Variable reactance part 5 Transmission circuit 6 Information storage part 7 Transmitter control part 8 Transmission electrode 10 Reactance value timing chart 11 _Vb value timing chart 12 _Vb value / reactance value relation diagram 13 Reactance Unit 15 Transmission Circuit 16 Modulation Circuit 17 Broadband AC Signal Source 20 Wideband AC Signal Source Output Diagram 21 Wideband AC Signal Source Output Diagram 22 Applied Value

Claims (4)

An electric field communication transmitter that induces an electric field in an electric field transmission medium and transmits information using the induced electric field,
Information storage means for storing the information;
Transmitting means for modulating and transmitting the information output from the information storage means with a carrier wave;
Resonance state between the stray capacitance between the transmitter ground and the ground ground and the stray capacitance between the electric field transmission medium and the ground ground by changing the reactance value so that the transmission voltage applied to the electric field transmission medium is maximized. Variable reactance means for controlling
Transmitter control means for controlling the reactance value in the variable reactance means and controlling the information output by the information storage means;
An electric field communication transmitter comprising: An electric field communication transmitter that induces an electric field in an electric field transmission medium and transmits information using the induced electric field,
Information storage means for storing the information;
Modulating the information output from the information storage means with a carrier wave, changing the frequency of the carrier wave so as to maximize the transmission voltage applied to the electric field transmission medium, and controlling resonance to transmit A transmission means;
Reactance means for inducing the electric field in the electric field transmission medium having a fixed reactance value;
Transmitter control means for controlling the frequency of the carrier wave in the transmission means and controlling the information output by the information storage means;
An electric field communication transmitter comprising: An electric field communication transmitter that induces an electric field in an electric field transmission medium and transmits information using the induced electric field,
Information storage means for storing the information;
Transmitting means for simultaneously modulating and transmitting the information output from the information storage means with a plurality of carrier waves;
Reactance means for inducing the electric field in the electric field transmission medium having a fixed reactance value;
Transmitter control means for controlling the information output by the information storage means;
An electric field communication transmitter comprising: The transmission means includes
The electric field communication transmitter according to claim 3, further comprising a broadband AC signal source for generating and transmitting a plurality of the carrier waves.

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