JP4191702B2 - Transmitter and transceiver - Google Patents

Description

  The present invention relates to a transmitter and a transceiver for inducing an electric field in an electric field transmission medium and receiving information using the induced electric field.

  Due to the miniaturization and high performance of portable terminals, wearable computers that can be attached to living bodies have been attracting attention. Conventionally, as information communication between such wearable computers, a transceiver is connected to a computer to form an integral structure, and an electric field induced by the transceiver is transmitted to the inside of a living body that is an electric field transmission medium, thereby transmitting and receiving information. A method of performing is proposed.

  In such a transceiver for electric field communication floating from the ground, in order to efficiently induce an electric field in the human body, a variable reactance is inserted between the transmission / reception electrode and the transmission circuit, and between the human body or the circuit ground and the ground ground. Resonance with stray capacitance is used. In order to bring the variable reactance into a resonance state, the reactance value is adjusted using an amplitude monitor unit, a control signal generation unit, an electric field detection optical unit, and a signal processing unit.

  In order to strengthen the electric field induced in the electric field communication, a method is adopted in which a variable reactance is inserted into the output of the transceiver to resonate with the living body and the ground capacitance of the transceiver and the stray capacitance of the transceiver ground and the ground ground (for example, Patent Document 1). 2).

  In an actual application, as shown in FIG. 11, a transmitter is constituted by the I / O circuit 100, the transmission circuit 101, the variable reactance unit 102, the reactance control unit 103, the electrode 105, and the insulating layer 106, Electric field communication is performed using the living body 104 as an electric field transmission medium.

  In the configuration of the transmitter shown in FIG. 11, the reactance value of the variable reactance unit 102 shown in FIG. The time when the reactance value becomes the target value from the start of adjustment at this time becomes shorter as the difference between the initial value target values at the start of adjustment is smaller.

The configuration of the conventional variable reactance unit 102 includes a capacitor Q115 to which a transmission signal is input, a buffer 114 to which a control signal is input, a fixed voltage power source 112, an inductor 107, a variable capacitor diode 108, and a capacitor R109. And a resistor L110 and a resistor M111.
JP 2004-153708 A United States Ptent Appplication Publication, Pub.No.:US2004/09226A1 Pub.Date:May13,2004

  However, in the above-described prior art, since the difference between the initial value and the target value is uncertain, the time until the end of the reactance value adjustment may be long. If the reactance value adjustment time is long, the time during which the amplitude monitor unit and the control signal generation unit are operating becomes long, resulting in increased power consumption or radiating unnecessary electromagnetic waves not related to communication. there were.

  The present invention has been made in view of the above-described problems. The object of the present invention is to reduce the difference between the initial value and the target value and adjust the reactance value at high speed, and to emit unnecessary electromagnetic waves. It is to provide a transmitter and a transceiver with low power consumption and low power consumption.

In order to solve the problem, the present invention according to claim 1 is directed to a transmitter for inducing an electric field based on data to be transmitted in an electric field transmission medium and transmitting the data using the induced electric field. The reactance value is changed so that the voltage of the transmission applied to the electric field transmission medium is maximized, and the stray capacitance between the transmitter ground and the ground ground according to the transmission and between the electric field transmission medium and the ground ground A self-adjusting / external control switching variable reactance unit and a reactance control unit for controlling a resonance state with the stray capacitance of the self-adjusting / external control switching variable reactance unit, a switchable variable reactance section, the self-regulating variable reactance section, inductor and indicia for resonating with the signal of the transmission In accordance with a direct current obtained by rectifying the transmission signal input to the resonance circuit with the variable capacitance diode, and a resonance circuit including a variable capacitance diode whose capacitance changes in accordance with the applied voltage. A resistor that generates a potential difference and applies the potential difference between an anode and a cathode of the variable capacitance diode; when a transmission signal is input, the reactance value thereof is changed to a value close to a resonance state, and the reactance control unit Outputs a control signal for setting the reactance value so that the amplitude of the transmission signal applied after the reactance value approaches the resonance state is maximized, and the variable reactance unit is based on the control signal. The reactance value is adjusted to a resonance state.

The present invention according to claim 2 includes the transmitter according to claim 1 and a receiver that receives the electric field based on the data to be received induced in the electric field transmission medium and obtains received data. It is characterized by that.

According to a third aspect of the present invention, in the second aspect, the receiver includes an electric field detection optical unit.

  According to the present invention, it is possible to provide a transmitter and a transceiver that can reduce a difference between an initial value and a target value and adjust a reactance value at high speed, reduce unnecessary electromagnetic wave radiation, and consume less power. Can do.

<First Embodiment>
FIG. 1 is a block diagram of the transmitter according to the first embodiment. This transmitter includes an I / O circuit 4, a transmission circuit 3, a reactance control unit 2, a self-adjusting / external control switching reactance control unit 1, a transmission / reception electrode 6, and an insulator 7. Can be used for electric field communication. In this transmitter, in order to control reactance at high speed, a variable reactance unit 1 is applied to a variable reactance unit.

  The internal configuration of the self-adjusting / external control switching variable reactance unit 1 is shown in FIG. In FIG. 2, a capacitor A16 that receives a transmission signal input, a buffer 18 that receives a control signal input, an inductor 14, a variable capacitance diode 13, a resistor A20, a resistor B21, a capacitor B15, and a fixed voltage power supply 12 A circuit ground 19, a filter 11, and an amplifier 17 are shown.

This self-adjusting / external control switching variable reactance unit 1 is a variable reactance unit that changes a reactance value by a control signal when a1 and c1 are connected by a switch A10 as shown in FIG. On the other hand, in the case of connecting the a1 and b1, V _DC by rectifying action of V _AC of the transmission signal having a voltage input variable capacitance diode _13, occurs I _D, resonant state reactance value of itself is changed It becomes a self-adjusting variable reactance section that approaches.

  The self-adjusting operation shown in FIG. 3 is shown in FIG. FIG. 4 shows changes in each voltage / current signal when it changes with respect to the stray capacitance and converges to a value close to optimum.

First, FIG. 4A shows the relationship of the DC component _ID of the current generated when an AC voltage having an amplitude | V _AC | is applied to the variable capacitance diode 13. I _D for the same V _AC for the period of the reverse bias voltage V _DC is generated across the variable capacitance diode 13 variable-capacitance diode 13 is a short circuit is shortened decreases.

4B is a graph of a potential difference (equivalent to _VDC ) generated when _ID flows through the resistors A20 and B21, and FIG. 4C shows the voltage V of the capacitor _CV of the variable capacitance diode 13. _DC dependency is shown. The FIG. 4 (d) the amplitude of _{V b} | a _{C V} dependent | _{V b.}

Points indicated by “1” to “4” in the graph indicate changes in each current voltage after the AC signal is input to the variable reactance. The initial value of the capacitance _{C V} is a value _{C 1} in the case of _{V DC} = 0. | V _AC | is proportional to | V _b |.

When an AC signal is input, it is rectified by the variable capacitance diode 13 to generate a DC current _ID (point 1 in FIG. 4A). When this flows through the resistor A20 and the resistor B21, a DC voltage _VDC is generated, and the same potential difference is also applied to the variable capacitance diode 13. As a result, the capacitance _CV decreases (point 1 in FIG. 4C), approaches the capacitance value causing resonance, and | _Vb | increases.

Since | V _AC | is proportional to | V _b |, | V _AC | increases, but V _DC also increases. _Therefore , the relationship between | V _AC | and _ID is as shown in FIG. Move to “2”. After this, C _V similarly decreases and | V _AC | increases, but V _DC also increases. Therefore, the amount of change in _ID gradually decreases and converges to zero. When the amount of change in _ID becomes zero, | V _AC | becomes constant and approaches the amplitude in the resonance state. The speed of this change depends on the size of the resistor A20, the resistor B21, the capacitor A16, and the capacitor B15.

  In the case of adjustment by the reactance control unit 2, it is determined whether or not the amplitude applied after setting the reactance value of the self-adjustment / external control switching variable reactance unit 1 is maximum. The operation of setting the reactance value is repeated to adjust to the resonance state.

  In this case, the time required for the amplitude to become constant after setting the reactance value once depends on the size of the resistors A20 and B21, and the capacitors A16 and B15. The reactance value can be adjusted at high speed by changing the reactance value close to the resonance state by the reactance unit that repeats this operation many times, and then adjusting the resonance state to the resonance state by the reactance control unit 2.

  A filter 11 and an amplifier 17 for outputting a reactance monitor signal are added in order to output the reactance value when the self-adjustable variable reactance is set to the reactance control unit 2. With the above configuration, a reactance value can be adjusted at high speed to reduce unnecessary electromagnetic radiation, and a transmitter with low power consumption can be provided.

  In FIG. 2, the switch A10 of the self-adjusting / external control switching variable reactance unit 1 is connected to the anode side of the variable capacitance diode 13, but may be connected to the cathode side as shown in FIG. Further, the same effect can be obtained by inserting the resistor 3 between the resistors A20 and B21 and outputting a monitor signal from a node between the resistors as shown in FIG.

  FIG. 7 shows a block diagram of a configuration of a transceiver to which the transmitter according to the first embodiment is applied. A receiving unit 23 is added to the configuration shown in FIG. 1 to amplify, filter, and demodulate the received signal and output it to the I / O circuit 4.

FIG. 8 shows a block diagram of another transceiver configuration. In this transceiver, a switch B24 for switching between transmission and reception is used. In the case of transmission, a2 and b2 are connected to connect the transmission circuit 3 and the self-adjusting / external control switching variable reactance unit 1. In the case of reception, b2 and c2 are connected and the received signal is input to the receiving unit 23. At this time, the reactance value of the self-adjusting / external control switching variable reactance unit 1 is set to the minimum.

  An electric field detection optical unit that optically detects an electric field may be used for the input stage of the reception unit 23.

<Second Embodiment>
FIG. 9 shows a second embodiment of the self-adjusting / external control switching variable reactance unit 1. In the AC signal, each capacitor is regarded as a short circuit, and a variable capacitance diode A29 and a variable capacitance diode B28 are connected in series. The voltage of the AC signal is divided and applied to each variable capacitance diode A29 and variable capacitance diode B28. The

  Therefore, even if the voltage of the AC signal increases in the resonance state, the voltage applied to each variable capacitance diode is halved, and resonance occurs due to the limitation of the voltage applied to the variable capacitance diode as compared with a single variable capacitance diode. Is less likely to occur.

  In the present embodiment, a total of two variable capacitance diodes, variable capacitance diode A29 and variable capacitance diode B28, are used, but two or more may be used. On the other hand, in the control signal having a low frequency, each capacitor can be regarded as open, and each variable capacitance diode is connected in parallel as viewed from the buffer amplifier 18. Therefore, the voltage of the control signal is applied as it is without being divided. In this embodiment, the circuit configuration prevents the suppression of resonance due to the applied voltage becoming higher than the withstand voltage and does not reduce the variable range of the capacitance.

<Third Embodiment>
FIG. 10 shows a third embodiment of the self-adjusting / external control switching variable reactance unit. The current-voltage characteristics of the variable capacitance diode are asymmetric. When the anode potential is high, a short circuit occurs when the anode potential is higher than a predetermined value determined by the semiconductor characteristics, and the amplitude of the AC signal is suppressed.

  In order to prevent this, the variable capacitance diode A29, the variable capacitance diode B28, the variable capacitance diode C31, and the variable capacitance diode D32 are connected in series and in the reverse direction with respect to the high-frequency AC signal. With this configuration, even if one of the variable capacitance diodes is short-circuited, the reverse-direction variable capacitance diode is not short-circuited, so that the amplitude of the AC signal is not suppressed.

  According to the embodiments described above, the reactance value can be adjusted at high speed by reducing the difference between the initial value and the target value, the emission of unnecessary electromagnetic waves is reduced, and a transmitter with low power consumption and A transceiver can be provided.

The whole block diagram of the transmitter which concerns on embodiment is shown. The block diagram of the self-adjustment / externality control switching variable reactance part which concerns on embodiment is shown. The block diagram of the self-adjustment variable reactance part which concerns on embodiment is shown. An explanatory view of operation of a self-adjustment variable reactance part concerning an embodiment is shown. The block diagram of the modification of the self-adjustment / external control switching variable reactance part which concerns on embodiment is shown. The block diagram of the modification of the self-adjustment / external control switching variable reactance part which concerns on embodiment is shown. The block diagram of the transceiver which concerns on embodiment is shown. The other block diagram of the transceiver which concerns on embodiment is shown. The block diagram of the modification of the self-adjustment / external control switching variable reactance part which concerns on embodiment is shown. The block diagram of the modification of the self-adjustment / external control switching variable reactance part which concerns on embodiment is shown. The block diagram of the transmission circuit by a prior art is shown. The block diagram of the variable reactance part by a prior art is shown.

Explanation of symbols

1 Self-adjustment / external control switching variable reactance part 2 Reactance control part 3 Transmitter circuit 4 I / O circuit 10 Switch A
11 Filter 12 Fixed Power Supply 13 Variable Capacitance Diode 14 Inductor 15 Capacitance B
16 capacity A
17 Amplifier 18 Buffer 20 Resistance A
21 Resistance B

Claims (3)

In a transmitter for inducing an electric field based on data to be transmitted in an electric field transmission medium and transmitting the data using the induced electric field,
The reactance value is changed so that the voltage of the transmission applied to the electric field transmission medium is maximized, and the stray capacitance between the transmitter ground and the ground ground for transmission is between the electric field transmission medium and the ground ground. A self-adjusting / external control switching variable reactance unit and a reactance control unit for controlling the resonance state with the stray capacitance,
The self-adjusting / external control switching variable reactance unit can be switched to a self-adjusting variable reactance unit and a variable reactance unit by a switch,
The self-adjusting variable reactance unit is
A resonance circuit including an inductor for resonating with the transmission signal and a variable capacitance diode whose capacitance changes according to an applied voltage;
A resistor that generates a potential difference according to a direct current obtained by rectifying the transmission signal input to the resonance circuit with the variable capacitance diode, and that applies the potential difference between an anode and a cathode of the variable capacitance diode; When the transmission signal is input, the reactance value of the device is changed to near the resonance state,
The reactance control unit outputs a control signal for setting the reactance value so that an amplitude of a transmission signal applied after the reactance value approaches a resonance state is maximized,
The variable reactance unit adjusts the reactance value to a resonance state based on the control signal . The transmitter of claim 1;
A transceiver comprising: a receiver that receives an electric field based on data to be received induced in an electric field transmission medium to obtain received data. The transceiver according to claim 2, wherein the receiver includes an electric field detection optical unit.

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