JP2008085918A - Electric-field communication transmitter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress degradation of success rate of transmission because of floating capacitance and improve reliability of communication of a portable electric-field communication transmitter. <P>SOLUTION: In an electric-field communication transmitter 100, there are provided first and second reactance adjusting sections 104a, 104b, the second reactance adjusting section 104b controlling a resonant condition with respect to a floating capacitance Cg and a floating capacitance Cb by causing its reactance value to vary to a greater value than a reactance value of the first reactance adjusting section 104a, and thereby if a resonant condition can not be controlled by the first reactance adjusting section 104a because of fluctuation of the floating capacitances Cg and Cb, then a selector 105 switches from a path via the first reactance adjusting section 104a to a path via the second reactance adjusting section 104b and causes the second reactance adjusting section 104b to control a resonant condition so as to be able to adjust a transmission voltage Vb to be applied to a human body to be maximized. <P>COPYRIGHT: (C)2008,JPO&INPIT

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, attention has been focused on wearable computers that can be attached to living bodies. Conventionally, electric field communication in which information is transmitted and received by connecting a transceiver to a computer and transmitting an electric field induced by the transceiver to a living body, which is an electric field transmission medium, has been proposed as information communication between such wearable computers. ing.

  Since this transceiver is used floating from the earth ground, a variable reactance is inserted between the transmitting and receiving electrodes and the transmitting circuit in order to efficiently induce an electric field in the human body, and the stray capacitance between the human body and the circuit ground and the earth ground. Transmission is performed using the resonance phenomenon. In the conventional transmission, in order to maintain the resonance phenomenon in accordance with the floating stray capacitance, the reactance value of the variable reactance is controlled by monitoring the electric field induced by the person using a part of the receiving unit. .

In recent years, there has been proposed an electric field communication transmitter capable of reducing a circuit scale while maintaining a resonance state corresponding to a variable stray capacitance by transmitting while changing a reactance value (for example, see Patent Document 1). reference).
JP 2006-81114 A

  However, electric field communication is affected by fluctuations in stray capacitance. In particular, portable electric field communication transmitters have a problem in communication reliability because the stray capacitance varies significantly depending on the place where they are carried and the transmission success rate decreases.

  In view of the above problems, an object of the present invention is to suppress a decrease in transmission success rate due to stray capacitance and improve communication reliability in an electric field communication transmitter.

  An electric field communication transmitter according to a first aspect of the present invention 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 is an information storage for storing information. Means for transmitting the information output from the information storage means by modulating with a carrier wave, and changing the reactance value between the transmission means and the electric field transmission medium to change the ground and ground of the transmitter First reactance adjustment means for controlling the stray capacitance between the ground and the resonance state of the stray capacitance between the electric field transmission medium and the ground to adjust the transmission voltage applied to the electric field transmission medium to a maximum; The reactance value is changed to a value larger than the reactance value between the transmission means and the electric field transmission medium to control the resonance state with the stray capacitance so that the transmission voltage is maximized. When the stray capacitance fluctuates with the second reactance adjusting means, the connection between the transmitting means and the electric field transmission medium is switched from the path via the first reactance adjusting means to the path via the second reactance adjusting means. Switching means. The electric field transmission medium in the present invention refers to a medium capable of transmitting an electric field, and includes, for example, a highly conductive member such as metal, a living body, an insulator, and the like.

  In the present invention, the reactance value is changed to a value larger than the reactance value of the first reactance adjusting means, and 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 are The second reactance adjusting means for controlling the resonance state of the first reactance adjusting means is provided. When the stray capacitance fluctuates and the resonance state cannot be controlled by the first reactance adjusting means, the first reactance adjusting means is changed by the switching means. Switching from the route through the route through the second reactance adjusting means, and controlling the resonance state by the second reactance adjusting means so that the transmission voltage applied to the electric field transmission medium is maximized. Is possible.

  The electric field communication transmitter further includes notification means for measuring an elapsed time and notifying that a preset time has elapsed, and the switching means is configured to transmit the transmission means and the electric field transmission medium when notified by the notification means. Is switched from the path via the first variable reactance means to the path via the second variable reactance means.

  In the present invention, by providing the notifying means for measuring the elapsed time and notifying that a preset time has elapsed, the first reactance adjustment is performed by the switching means when notified by the notifying means. Since the path through the means can be switched to the path through the second reactance adjustment means, the resonance state can be automatically controlled by adjusting the reactance value.

  An electric field communication transmitter according to a second aspect of the present invention 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 is an information storage for storing information. Between the transmitter ground and the ground ground by changing the reactance value between the transmitter, the transmission means for modulating the information output from the information storage means with a carrier wave, and the transmission means and the electric field transmission medium. Reactance adjusting means for adjusting the stray capacitance of the antenna and the resonance state of the stray capacitance between the electric field transmission medium and the ground to adjust the transmission voltage applied to the electric field transmission medium to the maximum, and the transmission means and the reactance adjustment Between the transmission means and the reactance adjustment means when the stray capacitance fluctuates, and the amplitude conversion means Characterized in that it and a switching means for switching the route.

  In the present invention, when the stray capacitance fluctuates by providing the amplitude conversion means for increasing the amplitude voltage of the carrier wave of the transmission voltage applied to the electric field transmission medium between the transmission means and the reactance adjustment means. In addition, if the reactance adjustment means cannot change the reactance value to control the resonance state with the stray capacitance so that the transmission voltage applied to the electric field transmission medium can be maximized, the switching means can change the amplitude conversion means. The amplitude voltage of the carrier wave of the transmission voltage can be increased by the amplitude conversion means.

  The electric field communication transmitter further includes notification means for measuring an elapsed time and notifying that a preset time has elapsed, and the switching means is a transmission means and reactance adjustment means when notified by the notification means Is switched to a path via an amplitude converting means.

  In the present invention, by providing a notification means for measuring the elapsed time and notifying that a preset time has elapsed, when the notification means notifies, the switching means passes the amplitude conversion means. Therefore, it is possible to automatically switch between control of the resonance state and adjustment of the amplitude voltage by adjusting the reactance value.

  According to the electric field communication transmitter of the present invention, it is possible to suppress a decrease in transmission success rate due to stray capacitance and improve communication reliability.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a diagram schematically showing a configuration of a gate system using the electric field communication transmitter according to the first embodiment. As shown in the figure, the gate system has a portable electric field communication transmitter 100 for transmitting unique information such as a user's ID and the earth 200 for detecting information via the user's human body. The installed sheet 300, the installed electric field communication receiver 400 for outputting the detected signal to the computer, the gate 500 for controlling the entry and exit of the user, and the signal from the electric field communication receiver 400 are registered in advance. And a computer 600 that opens and closes the gate 500 in comparison with the received information.

  The electric field communication transmitter 100 induces an electric field in an electric field transmission medium and transmits information using the induced electric field. Here, the electric field transmission medium is a human body. On the other hand, the installation type electric field communication receiver 400 detects the electric field induced in the electric field transmission medium and receives the information transmitted by the electric field communication transmitter 100. Here, the electric field transmission medium is a user's human body and an insulating sheet 300. In this manner, information is transmitted and received through the electric field transmission medium in the gate system.

  As shown in the block diagram of FIG. 2, the electric field communication transmitter 100 includes an information storage unit 107 for storing unique information, and a unique information output from the information storage unit 107 for modulating and transmitting with a carrier wave. The reactance value is changed between the transmission circuit 106, the transmission circuit 106, and the transmission electrode 109 as an electric field transmission medium to change the stray capacitance Cg between the circuit ground 130 and the ground ground 103 of the transmitter and between the human body and the ground ground 103. The reactance value is changed to a value larger than the reactance value of the first reactance adjustment unit 104a between the first reactance adjustment unit 104a that controls the resonance state with the stray capacitance Cb, and the transmission circuit 106 and the transmission electrode 109. The second reactance adjustment unit 104b for controlling the resonance state with the stray capacitances Cg and Cb, and the transmission circuit 10 A selector 105 for switching the connection between the transmission electrode 109 and the transmission electrode 109 from the path via the first reactance adjustment unit 104a to the path via the second reactance adjustment unit 104b, a switching button 113 connected to the selector 105, A transmitter control unit 108 for controlling reactance values in the first reactance adjustment unit 104a and the second reactance adjustment unit 104b and for controlling unique information output from the information storage unit 107 is provided.

  Here, a highly conductive metal is used for the transmission electrode 109 connected to the selector 105. The transmission electrode 109 is covered with an insulator 110, which is also an electric field transmission medium, and prevents a current from flowing directly to the human body. In this way, the transmission electrode 109 is in contact with the human body via the insulator 110, and the human body has a potential Vb between the ground electrode 103 and the ground.

  Next, control of the resonance state during normal operation of the electric field communication transmitter 100 will be described using the timing chart of FIG. The electric field communication transmitter 100 transmits the unique information at regular intervals W. The transmission of this information is executed in accordance with the reactance setting signal output from the transmitter control unit 108 by changing the reactance value in the first reactance adjusting unit 104a as shown in the timing chart of FIG. Here, the reactance value is divided into five stages (indicated by (1) to (5) in the figure), and the unique information is transmitted five times. By performing transmission while varying the reactance value in this way, the resonance state with the stray capacitances Cg and Cb is controlled. Therefore, as shown in the timing chart of FIG. The voltage Vb becomes the maximum value at the third reactance value (corresponding to the value indicated by (3) in the figure).

  Next, control of the resonance state when the stray capacitance of the electric field communication transmitter 100 is varied will be described with reference to the system configuration diagram of FIG. 1 and the timing chart of FIG. When the user of the gate system of FIG. 1 moves on the sheet 300 or the stray capacitances Cg and Cb change due to the displacement of the mounting position of the electric field communication transmitter 100, for example, as shown in FIG. Even if the reactance value is changed by one reactance adjustment unit 104a, the resonance state cannot be controlled, the voltage Vb between the human body and the ground 103 is not the maximum value, and the transmission success rate is lowered. The user recognizes this situation by not opening the gate 500.

  At this time, the user presses the switching button 113 of the electric field communication transmitter 100 and operates it by himself. Thus, in the electric field communication transmitter 100, the selector 105 switches the connection between the transmission circuit 106 and the electric field transmission medium from the path via the first reactance adjustment unit 104a to the path via the second reactance adjustment unit 104b. The reactance value is changed to values (6) to (10) larger than the reactance values (1) to (5) of the first reactance adjustment unit 104a by the second reactance adjustment unit 104b to control the resonance state. Thus, the transmission voltage Vb can be adjusted to a maximum. Therefore, since the decrease in the transmission success rate due to stray capacitance is suppressed, the reliability of communication can be improved.

  Therefore, according to the first embodiment, the reactance value is changed to a value larger than the reactance value of the first reactance adjustment unit 104a, and the stray capacitance Cg between the circuit ground 130 of the transmitter and the ground ground 103 and the human body are changed. And the second reactance adjustment unit 104b that controls the resonance state of the stray capacitance Cb between the ground ground 103 and the ground capacitance 103, the stray capacitances Cg and Cb fluctuate and the resonance state is changed by the first reactance adjustment unit 104a. When control is not possible, the selector 105 switches from the path via the first reactance adjustment unit 104a to the path via the second reactance adjustment unit 104b, and the resonance state is controlled by the second reactance adjustment unit 104b. It is possible to adjust so that the transmission voltage Vb applied to the human body is maximized. Therefore, it is possible to suppress a decrease in the transmission success rate due to stray capacitance and improve communication reliability.

In the first embodiment, the selector 105 serving as a switching unit for switching from the path via the first reactance adjustment unit 104a to the path via the second reactance adjustment unit 104b is the first reactance. Although the configuration is such that the adjustment unit 104a and the second reactance adjustment unit 104b are arranged on the output side, the present invention is not limited to this.
As a modification of the first embodiment, as shown in the block diagram of FIG. 5, the selector 105a is provided on the input side of the first reactance adjustment unit 104a and the second reactance adjustment unit 104b, and the output side is provided with a selector 105a. The selector 105b may be arranged. In such a configuration, it is not necessary to operate the second reactance adjustment unit 104b at normal times, so that the power consumption of the entire transmitter can be reduced.

[Second Embodiment]
Hereinafter, a second embodiment will be described. The configuration of the electric field communication transmitter according to the present embodiment is the same as the basic configuration described in the first embodiment. Below, it demonstrates centering on a different point from 1st Embodiment.

  The difference from the first embodiment is that, as shown in the block diagram of FIG. 6, in the electric field communication transmitter 100, a timer circuit is used as a notification means for measuring an elapsed time and notifying that a preset time has elapsed. 112, and selectors 105a and 105b as switching means connect the transmission circuit 106 and the transmission electrode 109 to the second through the route via the first reactance adjustment unit 104a when the timer circuit 112 receives a notification. It is a point which switches to the path | route via the reactance adjustment part 104b.

  For example, the timer circuit 112 starts measuring elapsed time based on the transmission time when the unique information is transmitted by the transmission circuit 106, and transmits a switching signal to the selectors 105a and 105b when a preset time has elapsed. . Here, the measurement time is set to 5 seconds, for example, and a switching signal is periodically transmitted to the selectors 105a and 105b every 5 seconds.

  When the timer circuit 112 receives a notification by a switching signal, the selectors 105a and 105b switch from the path via the first reactance adjustment unit 104a to the path via the second reactance adjustment unit 104b. As described above, the resonance state can be automatically controlled by adjusting the reactance value without requiring any operation by the user.

  Therefore, according to the second embodiment, the electric field communication transmitter 100 further includes the timer circuit 112 that measures the elapsed time and notifies that the preset time has elapsed. When notified by the output switching signal, the selectors 105a and 105b can switch from the path through the first reactance adjustment unit 104a to the path through the second reactance adjustment unit 104b. In addition to the effects according to the embodiment, the resonance state can be automatically controlled by adjusting the reactance value. Therefore, it is possible to suppress a decrease in the transmission success rate due to stray capacitance and improve communication reliability.

  In the second embodiment, the timer circuit 112 is configured to switch from the path via the first reactance adjustment unit 104a to the path via the second reactance adjustment unit 104b. It is not limited to this.

  As a modification of the second embodiment, an electric field communication transceiver 700 having a reception function in the electric field communication transmitter 100 is used. Specifically, as shown in the block diagram of FIG. 7, the electric field communication transceiver 700 detects an electric field induced in the electric field transmission medium and receives information by receiving an electric field detector 120 and a signal processing circuit 121. When the transmission error detection circuit 122 detects a transmission error, and when the transmission error detection circuit 122 detects a transmission error, the path through the first reactance adjustment unit 104a passes through the second reactance adjustment unit 104b. And a switching circuit 123 that transmits a switching signal for switching to the path to the selectors 105a and 105b.

  With such a configuration, the electric field communication transceiver 700 detects the electric field induced and transmitted by the human body as the reception function in addition to the transmission function by the transmission / reception electrode 114 covered with the insulator 110, This electric field is coupled to the electric field detector 120 and converted into an electric signal. The electric signal is subjected to signal processing such as amplification and noise removal in the signal processing circuit 121 and is output to the transmission error detection circuit 122.

  Here, when transmission error information is detected by the transmission error detection circuit 122, the switching circuit 123 transmits a switching signal to the selectors 105a and 105b. The selectors 105a and 105b switch from the path via the first reactance adjustment unit 104a to the path via the second reactance adjustment unit 104b. Even in such a configuration, it is possible to automatically control the resonance state by adjusting the reactance value in accordance with a decrease in the transmission success rate due to the stray capacitance without requiring any operation by the user himself / herself.

  In the second embodiment, the timer circuit 112 is provided as a notification means for measuring the elapsed time and notifying that a preset time has elapsed. However, the present invention is not limited to this. For example, it may be configured such that a preset time is measured by a counter circuit that counts in synchronization with the clock.

  Furthermore, in the second embodiment, the timer circuit 112 sets the measurement time to 5 seconds in advance and periodically sends a switching signal to the selectors 105a and 105b every 5 seconds. For example, the measurement time may be set irregularly as 1 second, 2 seconds, or 3 seconds, and the switching signal may be transmitted to the selectors 105a and 105b at irregular time intervals.

[Third Embodiment]
The third embodiment will be described below. The configuration of the electric field communication transmitter according to the present embodiment is the same as the basic configuration described in the first embodiment. Below, it demonstrates centering on a different point from 1st Embodiment.

  The difference from the first embodiment is that, as shown in the block diagram of FIG. 8, an amplitude conversion circuit 111 for increasing the amplitude voltage of the carrier wave is provided between the transmission circuit 106 and the reactance adjustment unit 104, and the amplitude conversion The selector 105 between the circuit 111 and the reactance adjustment unit 104 is to switch the connection between the transmission circuit 106 and the reactance adjustment unit 104 to a path via the amplitude conversion circuit 111 when the stray capacitance changes.

  The reactance adjustment unit 104 changes the reactance value between the transmission circuit 106 and the transmission electrode 109 to change 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. The resonance state is controlled and adjusted so that the transmission voltage Vb applied to the human body is maximized. The reactance value to be changed here is the same value as that described in FIG. 3 of the first embodiment.

  With this configuration, when the stray capacitance fluctuates and the resonance state is controlled by the reactance adjustment unit 104 and the transmission voltage applied to the human body cannot be adjusted to the maximum, the user himself The switch button 113 of the electric field communication transmitter 100 is pressed. As a result, the selector 105 in the electric field communication transmitter 100 switches to the path via the amplitude conversion circuit 111. At this time, according to the amplitude conversion setting signal output from the transmitter control unit 108, the amplitude conversion circuit 111 increases the amplitude voltage of the carrier wave of the transmission voltage. Here, for example, the amplitude conversion setting signal is set so as to increase the amplitude voltage of the carrier wave from 3V to 6V. As a result, it is possible to suppress a decrease in transmission success rate due to stray capacitance and improve communication reliability.

  Therefore, according to the third embodiment, the amplitude conversion circuit 111 that increases the amplitude voltage of the carrier wave of the transmission voltage Vb applied to the human body is provided between the transmission circuit 106 and the reactance adjustment unit 104. If the stray capacitance fluctuates and the reactance adjustment unit 104 controls the resonance state and cannot adjust the transmission voltage applied to the human body to the maximum, the selector 105 takes the path through the amplitude conversion circuit 111. By switching, the amplitude conversion circuit 111 can increase the amplitude voltage of the carrier wave of the transmission voltage. Therefore, it is possible to suppress a decrease in the transmission success rate due to stray capacitance and improve communication reliability.

  In the third embodiment, the amplitude conversion circuit 111 that increases the amplitude voltage of the carrier wave is provided between the transmission circuit 106 and the reactance adjustment unit 104. However, the configuration is limited to this configuration. Instead, for example, a structure including a reactance adjustment unit capable of changing the reactance value to a value larger than the reactance value of the reactance adjustment unit 104 between the transmission circuit 106 and the reactance adjustment unit 104, and stray capacitance and The resonance state may be controlled so that the transmission voltage is maximized.

[Fourth Embodiment]
Hereinafter, a fourth embodiment will be described. The basic configuration of the electric field communication transmitter according to the present embodiment is the same as that described in the third embodiment. Below, it demonstrates centering on a different point from 3rd Embodiment.

  The difference from the third embodiment is that, as shown in the block diagram of FIG. 9, a timer circuit 112 is further provided as a notification means for measuring the elapsed time and notifying that a preset time has elapsed, and switching The selector 105 as a means is that the connection between the transmission circuit 106 and the reactance adjustment unit 104 is switched to a path via the amplitude conversion circuit 111 when the timer circuit 112 is notified.

  The timer circuit 112 is assumed to have the same function as the timer circuit 112 described in the second embodiment. When the timer circuit 112 receives a notification using a switching signal, the selector 105 switches the connection between the transmission circuit 106 and the reactance adjustment unit 104 to a path via the amplitude conversion circuit 111. In this way, switching between resonance state control and amplitude voltage conversion by adjusting the reactance value can be automatically performed without requiring an operation by the user himself / herself.

  Therefore, according to the fourth embodiment, the timer circuit 112 is notified by measuring the elapsed time and providing the timer circuit 112 as notification means for notifying that a preset time has elapsed. In some cases, the selector 105 can switch the connection between the transmission circuit 106 and the reactance adjustment unit 104 to the path via the amplitude conversion circuit 111, so that in addition to the effect according to the third embodiment, the reactance value It is possible to automatically switch between control of the resonance state by adjustment and conversion of the amplitude voltage. Therefore, it is possible to suppress a decrease in the transmission success rate due to stray capacitance and improve communication reliability.

  In the fourth embodiment, when the timer circuit 112 is notified, the connection between the transmission circuit 106 and the reactance adjustment unit 104 is switched to the path via the amplitude conversion circuit 111. However, it is not limited to this.

  As a modification of the fourth embodiment, an electric field communication transceiver 700 having a reception function in the electric field communication transmitter 100 is used. Specifically, as shown in the block diagram of FIG. 10, the electric field communication transceiver 700 detects the electric field induced in the electric field transmission medium and receives the information as an electric field receiving unit that receives information and the electric field detection unit 120 and the signal processing circuit 121. The packet error rate of the transmitted packet is detected, and when the detected error rate of the transmitted packet is low, the connection between the transmission circuit 106 and the reactance adjustment unit 104 is switched to the path via the amplitude conversion circuit 111. A packet error rate detection circuit 124 that transmits a switching signal to the selector 105 is further provided.

  The packet error rate detection circuit 124 calculates the packet error rate from the total number of transmitted packets and the number of received and received packets, and when the packet error rate is low, the amplitude value to be amplified by the amplitude conversion circuit 111 is calculated. The setting signal shown is transmitted.

  With such a configuration, when the packet error rate detected by the packet error rate detection circuit 124 is low, the selector 105 can switch to a path via the amplitude conversion circuit 111. Even in such a configuration, it is possible to automatically control the resonance state by adjusting the reactance value in accordance with a decrease in the transmission success rate due to the stray capacitance without requiring any operation by the user himself / herself.

  In the gate system of each of the above embodiments, the electric field communication transmitter is a portable type, and the electric field communication receiver to be a communication partner is an installation type. However, the present invention is not limited to such a system configuration. Even when applied to a system in which portable devices communicate with each other, the same effects as in the present embodiment can be achieved.

  In each of the above embodiments, the gate system has been described as an example of a system using an electric field communication transmitter. However, the present invention is not limited to this. For example, a fee payment system in an transportation facility, an ID card, In the security system for use, the electric field communication transmitter according to the present invention may be used.

It is a figure which shows roughly the structure of the gate system using the electric field communication transmitter which concerns on 1st Embodiment. It is a block diagram which shows schematically the structure of the said electric field communication transmitter. It is a timing chart which shows control of the resonant state in the normal time of the said electric field communication transmitter. It is a timing chart which shows control of the resonance state at the time of the stray capacitance fluctuation of the above-mentioned electric field communication transmitter. It is the block diagram shown roughly about the modification of the structure of the said electric field communication transmitter. It is a block diagram which shows roughly the structure of the electric field communication transmitter which concerns on 2nd Embodiment. It is the block diagram shown roughly about the modification (electric field communication transceiver) of the structure of the said electric field communication transmitter. It is the block diagram which showed roughly the structure of the electric field communication transmitter which concerns on 3rd Embodiment. It is the block diagram which showed roughly the structure of the electric field communication transmitter which concerns on 4th Embodiment. It is the block diagram shown roughly about the modification (electric field communication transceiver) of the structure of the said electric field communication transmitter.

Explanation of symbols

100 ... Electric field communication transmitter (portable)
DESCRIPTION OF SYMBOLS 103 ... Earth ground 104 ... Reactance adjustment part 104a ... 1st reactance adjustment part 104b ... 2nd reactance adjustment part 105, 105a, 105b ... Selector 106 ... Transmission circuit 107 ... Information storage part 108 ... Transmitter control part 109 ... Transmission Electrode 110 ... Insulator 111 ... Amplitude conversion circuit 112 ... Timer circuit 113 ... Switch button 114 ... Transmission / reception electrode 120 ... Electric field detection unit 121 ... Signal processing circuit 122 ... Transmission error detection circuit 123 ... Switch circuit 124 ... Packet error rate detection circuit 130 ... Circuit ground 200 ... Earth 300 ... Sheet 400 ... Electric field communication receiver (installation type)
500 ... Gate 600 ... Computer 700 ... Electric field communication transceiver (portable)
Cg: stray capacitance between circuit ground and ground Cb: stray capacitance between human body and ground Vb: voltage between human body and ground

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;
The reactance value is changed between the transmission means and the electric field transmission medium to control the 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. First reactance adjusting means for adjusting the transmission voltage applied to the electric field transmission medium to be maximum;
Between the transmission means and the electric field transmission medium, the reactance value is changed to a value larger than the reactance value, and the resonance state with the stray capacitance is controlled to adjust the transmission voltage to the maximum. A second reactance adjusting means;
Switching means for switching the connection between the transmission means and the electric field transmission medium from the path via the first reactance adjustment means to the path via the second reactance adjustment means when the stray capacitance fluctuates. When,
An electric field communication transmitter comprising: A notification means for measuring the elapsed time and notifying that a preset time has elapsed;
The switching means connects the transmission means and the electric field transmission medium from the path via the first reactance adjusting means to the path via the second reactance adjusting means when notified by the notifying means. The electric field communication transmitter according to claim 1, wherein the electric field communication transmitter is switched 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,
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;
The reactance value is changed between the transmission means and the electric field transmission medium to control the 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. Reactance adjusting means for adjusting the transmission voltage applied to the electric field transmission medium to be maximum;
An amplitude converting means for increasing an amplitude voltage of the carrier wave between the transmitting means and the reactance adjusting means;
A switching means for switching the connection between the transmission means and the reactance adjustment means to a path via the amplitude conversion means when the stray capacitance fluctuates;
An electric field communication transmitter comprising: A notification means for measuring the elapsed time and notifying that a preset time has elapsed;
The electric field according to claim 3, wherein the switching unit switches the connection between the transmission unit and the reactance adjustment unit to a path via the amplitude conversion unit when notified by the notification unit. Communication transmitter.

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