JPH06216814A - Data carrier system - Google Patents

Abstract

PURPOSE:To prevent the crosstalk of an adjacent fixed equipment with the use of a common synchronizing signal by transmitting this signal to another fixed equipment from a synchronous signal generator means incorporated in a specific fixed equipment via an insulator means which is insulated in terms of DC. CONSTITUTION:An electromagnetic coupling type data carrier 16 having no power supply is provided together with a fixed equipment which performs the bidirectional communication of data to the carrier 16. Then the synchronous signals are transmitted to plural fixed equipments from an oscillator 1 incorporated in a specific fixed equipment via an insulator means 18 which is insulated in terms of DC. So that the same frequency and the same phase are secured among plural fixed equipments in regard of the AC magnetic field that is generated for transmission of the electric power and the data to the carrier 16 from the fixed equipment. Thus, the crosstalk caused by an adjacent fixed equipment can be prevented by a common synchronous signal. Thus it is possible to prevent the electric shock produced at a fixed equipment by the falling of a thunderbolt from affecting other fixed equipments.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data carrier system using a non-powered electromagnetically coupled data carrier, and more particularly to a two-way data communication between a data carrier and a fixed facility. The present invention relates to a technique for preventing mutual interference between a plurality of fixed facilities arranged close to each other and preventing electric shock from hitting another fixed facility when one fixed facility is hit by lightning.

[0002]

2. Description of the Related Art A data carrier system using a non-power-supply electromagnetically coupled data carrier has not been realized which enables bidirectional data communication between a data carrier and a fixed facility. A non-volatile memory called MONOS is mounted on a CMOS / IC that has high power consumption and high performance, and various modifications have been made to develop a rewritable electromagnetic coupling type data carrier and a fixed facility for the electromagnetic coupling type data carrier. Already filed as Japanese Patent Application No. 4-60917.

Conventionally, a system using an electromagnetically coupled data carrier of no power source performs only one-way communication from the data carrier to the fixed facility. In many of these systems, an alternating magnetic field generated by the fixed facility is used. Since it is a non-modulated power signal, it is in a steady state, and the combined field of AC magnetic fields created by a plurality of fixed facilities is also in a steady state, so that fixed facilities do not interfere with each other and data communication does not go wrong. However, as in the invention of the prior application, in the case of a system in which data is sent to a data carrier by modulating an AC magnetic field emitted from a fixed facility, an extremely large fluctuation of the AC magnetic field occurs, so an adjacent fixed facility located at a considerable distance. When the frequency of the AC magnetic field generated by the data carrier is the same as the frequency of the AC magnetic field generated by the fixed facility, the induced electromotive force changes in the antenna coil of the It is very difficult to distinguish it from the change in induced electromotive force due to the AC magnetic field emitted from the carrier, and there is a drawback that it is difficult to read correct data from the data carrier due to interference from the adjacent fixed facility. In order to overcome this problem, the invention of the prior application is provided with a synchronization signal generating means only in a specific fixed facility among a plurality of fixed facilities, and the synchronization signal generating means built in this specific fixed facility is used to transfer to a plurality of other fixed facilities. The interference signal is solved by transmitting and supplying a synchronization signal via a cable and operating all fixed facilities with the same synchronization signal.

[0004]

However, in this technique, since a plurality of fixed facilities are connected by the cable for transmitting and supplying the synchronous signal, all the fixed facilities result in being DC-coupled, There is a problem that when a lightning strikes one fixed facility, the electric shock is transmitted to other fixed facilities and all the fixed facilities are destroyed. Furthermore, if the power supply of a specific fixed facility fails and the power supply is dropped,
There is also a problem that the synchronizing signal generating means stops functioning and all of the plurality of fixed facilities become inoperable.

An object of the present invention is to solve the problems of the above-mentioned prior invention, to prevent interference from an adjacent fixed facility by a common synchronizing signal, and also to prevent electric shock from hitting another fixed facility when a lightning strike strikes another fixed facility. Another object of the present invention is to provide a data carrier system capable of preventing a facility from extending, and yet another object to provide a data carrier system in which the synchronization signal generating means provided in a specific fixed facility does not stop functioning. Especially.

[0006]

In order to solve the above-mentioned problems, an electromagnetically coupled data carrier of a non-power source and a fixed facility for bidirectional data communication between the data carrier are used. In order to make the frequency and phase of the AC magnetic field emitted for transmitting power and data to the carrier the same among multiple fixed facilities, the synchronization signal generating means built in a specific fixed facility can be used to fix other multiple fixed facilities. In a data carrier system for transmitting and supplying a synchronization signal to a facility, the synchronization signal is transmitted and supplied to another fixed facility by an insulating means that is galvanically isolated from the synchronization signal generating means built in the specific fixed facility. Further, the synchronization signal generating means built in a specific fixed facility is driven by at least two or more different power sources.

[0007]

In the above structure, the frequency and phase of the alternating magnetic field emitted from the fixed facility for transmitting electric power and data to the data carrier are the same in a plurality of fixed facilities so that they are the same. Since the synchronizing signal is transmitted from the built-in synchronizing signal generating means to another fixed facility by means of an insulating means that is galvanically insulated, even if a lightning strike occurs in one fixed facility, electric shock will occur only in that fixed facility and The fixed facility will not be reached. Further, since the power supply of the synchronizing means is supplied by two or more means, even if the supply of one is stopped, the operation is ensured by the other power supply, so that the supply of the synchronizing signal is maintained and the plurality of fixed facilities all stop functioning. There is nothing to do.

[0008]

FIG. 3 is a circuit block diagram showing an embodiment of an electromagnetic coupling type data carrier used in the data carrier system of the present invention. The data carrier of this embodiment is called a resonance condition control type and has an LC resonance circuit including a coil 18 and a capacitor 19 which are magnetically coupled to a fixed facility. The rectifier circuit 2 converts the electric power induced in the resonance circuit by the AC magnetic field generated from the fixed facility.
Power supply voltage Vd of the data carrier main circuit 23 after rectified by
d. A data signal superposed on an AC magnetic field and sent out from a fixed facility near the data carrier is demodulated by detecting the terminal voltage of the resonance circuit by a detection circuit 21, and the data carrier main circuit as an input signal Din. Transmitted to. On the other hand, the data carrier main circuit transmits the output data Dout to the modulation circuit 20, and the modulation circuit 2
By changing the impedance of 0 and changing the resonance condition of the resonance circuit, the current flowing through the coil 18 is increased or decreased. The change in the current changes the AC magnetic field around the data carrier, and the change in the AC magnetic field changes the electric power induced in the antenna coil of the fixed facility.

FIG. 2 is a circuit diagram for explaining the phase relation of the alternating current flowing through the antenna coil of the fixed facility in the data carrier system of the present invention in relation to the characteristics of the data carrier. In the drawing, the circuit on the left side represents the antenna coil of the fixed facility and its driving circuit, and the circuit on the right side represents the resonant circuit of the data carrier. In a fixed facility, the output voltage (hereinafter, referred to as drive voltage) v1 of the antenna drive circuit is defined by the following equation. Here, V1 represents voltage amplitude, ω0 represents angular frequency, and t represents time.

[0010]

## EQU00001 ## v1 = V1sin (.omega.0t)

The inductance of the antenna coil is L1,
Let C1 be the capacitance of the resonance capacitor connected in series to the antenna coil and R1 be the resistance of the antenna coil,
Once the electromotive force Δv1 induced in this antenna coil by the AC magnetic field generated by the data carrier is ignored,
The current i1 flowing through the antenna coil is expressed by the following equation.

[0012]

## EQU00002 ## i1 = v1 = V1sin (.omega.0t) Z
1 R1 + jωL1 + 1 jωC1

Here, Z1 is the load impedance of the antenna drive circuit. Now, let the series circuit of the antenna coil and the resonance capacitor resonate at the frequency of the drive voltage v1.
When 1 and C1 are selected, Z1 = R1 is established, and therefore the equation 2 is expressed by the following equation, and it can be seen that the phase of the current i1 of the antenna coil becomes equal to the phase of the drive voltage v1.

[0014]

## EQU00003 ## i1 = V1sin (.omega.0t) R1

Since the strength φ1 of the alternating magnetic field generated by the antenna coil is proportional to the current i1 of the antenna coil, the following equation is obtained, and its phase is equal to the phase of the driving voltage v1. Here, α is a constant determined by the shape of the antenna coil and the distance from the antenna coil, and Φ1 is the amplitude of the AC magnetic field of the antenna coil.

[0016]

## EQU00004 ## .phi.1 = .alpha.V1sin (.omega.0t) =. Phi.1s
in (ω0t) R1

The electromotive force v2 induced in the resonance circuit of the data carrier by the above AC magnetic field is the strength φ1 of the AC magnetic field.
Since it is proportional to the differential value of, the following equation is derived from Equation 4. However, β is a constant determined from the shape of the coil of the data carrier, and V2 is the amplitude of the electromotive force v2.

[0018]

V2 = dφ1 = βd [Φ1sin (ω0
t)] dt dt = V2cos (ω0
t) = V2sin (ω0t + π / 2)

As is clear from the above equation, the phase of the electromotive force v2 induced in the resonance circuit of the data carrier is advanced by 90 ° from the phase of the drive voltage v1 of the fixed facility. Now in the data carrier, the coil inductance is L2, the resonance capacitor capacitance is C2, and the coil resistance is R2.
Further, if L2 and C2 are selected so as to satisfy the resonance condition, the current i2 flowing through the coil is expressed by the following equation.

[0020]

I2 = V2sin (ω0t + π / 2) R
2 + jωL2 + 1 jωC2 = V2sin (ω0t +
π / 2) R2

The strength φ2 of the alternating magnetic field generated by the current flowing through the coil of the data carrier is as follows. However, Φ2
Is the amplitude of the alternating magnetic field generated by the data carrier.

[0022]

(7) φ2 = Φ2sin (ω0t + π / 2)

The electromotive force Δv1 induced in the antenna coil of the fixed facility by this AC magnetic field is given by the following equation with its amplitude being ΔV1.

[0024]

Δv1 = dφ2 = ΔV1cos (ω0t
+ Π / 2) dt = ΔV1sin (ω0t + π) = − ΔV
1 sin (ω0t)

Equation 8 shows that the phase of the electromotive force induced in the antenna coil of the fixed facility by the data carrier is advanced by 180 ° with respect to the phase of the driving voltage of the antenna coil itself. The voltage that drives the antenna coil of the fixed facility is the sum of the drive voltage v1 and the electromotive force represented by the equation (8). Therefore, correctly, in Equations 2 and 3, Δ
v1 must be taken into consideration, but the drive voltage v
Since 1 is much larger than the electromotive force Δv1, it can be practically ignored.

Next, the relationship between the above-mentioned first fixed facility and the adjacent second fixed facility will be considered. In the data carrier system of the present invention, since the reference alternating voltage is supplied by the synchronizing means between the adjacent fixed facilities, its frequency and phase are the same, so the second fixed facility is the first fixed facility. Noise AC magnetic field φn exerted on the facility is expressed by equation 4
Similarly to, it is expressed as the following equation. Here, Φn is the amplitude of the noise AC magnetic field.

[0027]

Φn = Φnsin (ω0t)

The electromotive force vn of the noise induced in the antenna coil of the first fixed facility is obtained by differentiating the equation 9, and is given by the following equation. Here, Vn is the amplitude of the electromotive force of noise.

[0029]

(10) vn = dφn = Vncos (ω0t) d
t = Vnsin (ω0t + π / 2)

As is clear from the equation (10), the phase of the electromotive force of the noise induced by the adjacent fixed facilities is the drive voltage v.
It leads the phase of 1 by 90 degrees. As described above, the driving voltage v1 is applied to the antenna coil of the fixed facility,
The electromotive force Δv1 induced by the data carrier and the electromotive force vn of noise due to a nearby fixed facility are applied in series. Therefore, the total driving voltage v of the antenna coil
Is expressed as follows from the equations 1, 8, and 10.

[0031]

V = V1sin (ω0t) −ΔV1si
n (ω0t) + Vnsin (ω0t + π / 2)

The current i flowing through the antenna coil is expressed as follows.

[0033]

I = v = V1sin (ω0t) R1
R1-ΔV1sin (ω0t) R1 + Vnsin (ω
0t + π / 2) R1

As is clear from the equations 11 and 12, the phases of the first and second terms are the same as the phase of the driving voltage v1 for both the current i and the voltage v, so that the signals in phase with the driving voltage are synchronized. By performing synchronous rectification as a signal, the rectification yield can be made 100%. On the other hand, the yield of the third term is 0
%, The effect of noise can be completely eliminated. }

FIG. 1 is a block diagram showing an embodiment of a fixed facility of the data carrier system of the present invention. Reference numeral 1 denotes an oscillator which is a synchronizing signal generating means and generates a synchronizing signal which is transmitted and supplied to a plurality of other fixed facilities. Reference numeral 2 denotes a changeover switch, which selects an output signal of the oscillator 1 or a signal externally supplied to the ACin terminal, and selects an AC signal A of the fixed facility.
Let be C. Reference numeral 18 denotes an insulating means, which insulates a signal supplied from the outside from the fixed facility in a DC manner. The AC signal AC is transmitted from the signal output terminal ACout to A of another fixed facility in the vicinity.
It is supplied to the Cin terminal. Similarly, the ACin terminal of another fixed facility is also provided with an insulating means so that the AC signal is DC-insulated and supplied. This allows the two fixed installations in question to use the exact same AC signal AC,
Moreover, since the two fixed facilities are galvanically isolated, an abnormal electric shock caused by, for example, a lightning strike in one of the fixed facilities cannot be conducted to the other. In this embodiment, the AC signal AC is generated by the modulation circuit 3, the voltage adjustment circuit 7,
It is distributed to the phase adjustment circuit 11.

The modulation circuit 3 modifies the AC signal AC according to the output data DATAout given from the information processing circuit 17, that is, the data to be sent to the data carrier. The modulation method includes frequency modulation, phase modulation, amplitude modulation and the like, and any of them may be used, but the most effective use of the effect of the present invention is the binary amplitude modulation method. The method was adopted.

The antenna drive circuit 4 power-amplifies the output signal of the modulation circuit 3 and drives the antenna 6 via the current-voltage converter 5. The antenna 6 is composed of a series resonance circuit of an antenna coil and a capacitor, and its resonance frequency matches the frequency of the AC signal AC. As described above, the AC magnetic field φ1 is output from the antenna 6, and the AC magnetic field φ2 is returned from the data carrier 16 that has received the energy. The current of the antenna 6 is converted into a voltage by the current-voltage converter 5 and becomes the first input voltage Vo of the subtraction circuit 8. The first input voltage Vo is equal to
It is obtained by multiplying 1 or equation 12 by a coefficient and is expressed by the following equation.

[0038]

[Equation 13] Vo = kV1sin (ω0t) −kΔV
1 sin (ω0t) + kVn sin (ω0t−π / 2)

The second input voltage of the subtraction circuit 8 is the AC voltage Vs obtained by adjusting the voltage of the AC signal AC by the voltage adjusting circuit 7. If the voltage adjusting circuit 7 is adjusted so that the AC voltage Vs becomes equal to the first term of the equation 13, the output voltage of the subtraction circuit 8 when the data is not transmitted from the fixed facility is the second term of the equation 13. It is expressed only in the third term. That is,
It does not include the voltage corresponding to the current directly driven by the antenna drive circuit 4. Therefore, the voltage amplitude becomes small and can be amplified by the amplifier circuit 9. The output voltage of the amplifier circuit 9 is guided to the synchronous rectification circuit 10 which uses the output voltage Vr of the phase adjustment circuit 11 as a synchronization signal, and is rectified and detected. At this time, the yield of the third term of Expression 13 is 0% in principle, but a phase shift may occur due to an error factor of the circuit such as the amplifier 9. In order to compensate for this phase shift and make the noise term yield 0%, the phase adjustment circuit 11 is adjusted to change the phase of the synchronization signal. This allows the output signal of the synchronous rectifier circuit 10 to contain only the components induced by the data carrier.

If there is no subtraction circuit 8 and the output voltage of the current-voltage converter 5 is directly used as the input of the amplifier circuit 9, the output of the amplifier circuit will be saturated immediately and the amplification factor cannot be increased. Not only that, but there is a slight deviation in the phase accuracy of the synchronization signal in the synchronous rectification.
The yield with respect to the first term of 3 largely changes, and the error generated thereby becomes relatively large. Therefore, the roles of the voltage adjusting circuit 7 and the subtracting circuit 8 are extremely important for improving the reliability in demodulating the data transmitted from the data carrier.

FIG. 4 shows the output signal of the synchronous rectification circuit 10. The detection output has a waveform as shown in FIG. 4 (waveform a), but the carrier component is removed by the low-pass filter 12, and the low frequency component and the rectangular waveform as shown in FIG. 4 (waveform b) are combined waveforms. become. At this stage, information on the distance between the data carrier and the fixed facility is still superimposed on the signal. The information on this distance is specifically the magnitude of the electromotive force Δv1, and the DC voltage having a magnitude proportional thereto is superimposed. This superimposed DC voltage changes as the distance between the data carrier and the fixed facility changes, which causes the input operating point of the waveform shaping comparator circuit to be undefined.

In this embodiment, the output signal of the low-pass filter 12 is differentiated by the differentiating circuit 13 in order to remove the superimposed DC voltage. This removes low frequency signals due to relatively slow changes such as the data carrier moving closer to or further from the fixed facility, but does not produce sharp changes such as bit changes in the digital data sent by the data carrier. It is transmitted without deterioration and becomes a differential waveform as shown in (waveform C) of FIG.

The differentiated waveform is transmitted to the waveform shaping circuit 15 via the gate circuit 14. At this time, the gate circuit 14 outputs the gate control signal MASK output from the information processing circuit 17.
When the fixed facility is transmitting data, that is, when the information processing circuit 17 outputs the output data DATAou.
When transmitting t, the signal is not passed. As a result, the signal input to the waveform shaping circuit 15 is only the signal sent from the data carrier. The waveform shaping circuit 15 raises the signal with the positive pulse of the differential waveform and lowers it with the negative pulse to generate a rectangular wave data signal as shown in (waveform D) of FIG. The data signal is input data DATAin as the information processing circuit 1
Sent to 7.

FIG. 5 shows the embodiment of FIG. 1 in a more specific circuit diagram. The oscillator 1 is composed of a crystal oscillator having a C-MOS inverter as an amplifier and a bandpass filter. The bandpass filter removes the distortion of the waveform included in the oscillation output of the crystal oscillator to generate an extremely coherent AC signal. You can

Reference numeral 2 is a changeover switch for switching between an internal AC signal and an external synchronization signal. Reference numeral 18 denotes an insulating means, which is an embodiment using a transformer. The modulation circuit 3 is realized by an inverting amplifier using an operational amplifier, and a part of the feedback resistor is turned on / off by the transmission gate, and the amplitude of the AC signal is modulated in two steps by changing the amplification degree.
At this time, the control signal of the transmission gate is the output data DATAout.

The antenna drive circuit 4 is composed of a voltage follower circuit of a power operational amplifier.

The current-voltage conversion circuit 5 is realized by a transformer. The number of primary windings of this transformer is not so large and care must be taken not to hinder the power supply to the antenna 6.

The antenna 6 is installed at a location away from the main body of the fixed facility using a coaxial cable, and is composed of a series resonance circuit of an antenna coil and a capacitor. The capacitor is composed of a fixed capacitor and a variable capacitor connected in parallel, and the resonance condition can be adjusted by the variable capacitor.

The voltage adjusting circuit 7 is composed of an inverting amplifier circuit of an operational amplifier, but its feedback resistance is a variable resistance, and the amplitude of the output voltage can be changed by adjusting this.

The subtraction circuit 8 is a high input impedance operational amplifier constructed by using two operational amplifiers. The operational amplifier has the function of the amplifier circuit 9 as well as the subtraction function.

The synchronous rectifier circuit 10 is an operational amplifier circuit that saturates and amplifies the synchronous signal Vr to generate a rectangular synchronous signal, and the synchronous signal is converted into two gate control signals having a good rising characteristic and having a complementary relationship with each other. Two CMs to convert
It is composed of an OS inverter, two transmission gates which are turned on and off by the gate control signal, and an operational amplifier composed of an operational amplifier. The waveform of the output signal of this synchronous rectification circuit is (waveform B) in FIG. 4 described above.
In order to obtain a full-wave rectified waveform as described above, the phases of the two gate control signals must match the phase of the input signal of the synchronous rectification circuit 10. Therefore, a means for adjusting the phase of the synchronization signal Vr is needed.

The phase adjustment circuit 11 is composed of two phase feed circuits composed of operational amplifiers. The first phase feed circuit delays the phase of the AC signal AC by 90 °, and the subsequent phase feed circuit advances the once delayed signal by 90 ° so that there is no phase shift in total. However, by changing the constant of the phase feed circuit in the latter stage,
When the shift amount is near 0 °, it can be adjusted in the plus direction or the minus direction.

The low pass filter 12 is a double feedback type active low pass filter using an operational amplifier.
The differential circuit 13 is configured by directly connecting stages, and includes a capacitor input type differential circuit and a voltage follower circuit of an operational amplifier.

The gate circuit 14 is composed of a transmission gate which is turned on / off by the gate control signal MASK output from the information processing circuit 17, and cuts off the differential waveform by directly connecting the output of the differentiating circuit 13 to the negative power source V-. You can do it.

The waveform shaping circuit 15 is a comparator using an operational amplifier. Since the comparator is provided with a hysteresis characteristic, by the plus pulse and the minus pulse alternately output from the differentiating circuit 13,
Turn the output up or down. Further, when data is being sent from the fixed facility, the gate circuit 14 inputs a negative power supply voltage to the comparator, so that its output voltage is kept at a low level. Therefore, the reception of data from the data carrier always starts from a low level.

FIG. 6 shows a synchronizing signal generating means built in a specific fixed facility, that is, a power supply circuit for driving the oscillator 1. In the figure, reference numeral 19 denotes a DC power supply, which generates a DC voltage for driving an oscillator, which is a synchronizing signal generating means, from an ordinary commercial power supply. Reference numeral 20 denotes a battery, which supplies a DC voltage to the oscillator 1 when the DC power supply 19 stops functioning for some reason. A switch 21 switches the DC power source 19 and the battery 20 manually or automatically.

In FIG. 7, the output signal of the oscillator built in the fixed facility A is taken out from ACout, and the other fixed facility B,
This is a method of allocating to ACin terminals of C and D. In this type of connection method, it is necessary to increase the output power of the oscillator built in the fixed facility A, but the synchronization accuracy of each fixed facility can be increased. On the other hand, in FIG. 8, the output signal of the oscillator built in the fixed facility A is taken out from the ACout terminal and is distributed to the ACin terminal of the fixed facility B.
This is a method of connection using a potato type in which the in terminal is connected to the ACin terminal of the fixed facility C. In this method, a large number of fixed facilities can be used as a series by equipping each fixed facility with a relay amplifier, but there is a drawback that the phase shift due to the relay amplifier is accumulated. It is clear that, in both the systems of FIG. 7 and FIG. 8, if the insulating means is provided immediately after the ACin terminal, the synchronous signal can be insulated in a direct current manner.

Although the embodiment of the present invention has been described in detail with reference to FIG. 5, various other implementation circuits of the present invention can be considered. That is to say, the 18 insulating means may be, for example, an optical coupling method using a light emitting element and a light receiving element, a sound coupling method using ultrasonic waves, a wireless method using radio waves, or the like. Needless to say, the method is not limited to a transformer. The purpose can be achieved even if the battery is replaced with a DC power source obtained from a commercial power source of another system.

[0059]

According to the present invention, in a data carrier system having a plurality of fixed facilities, noise induced by an AC magnetic field generated by another adjacent fixed facility is compressed,
In addition to the above, in the above configuration, the frequency and phase of the AC magnetic field emitted from the fixed facility for transmitting power and data to the data carrier are made the same among a plurality of fixed facilities. A plurality of fixed facilities are provided because the electric power induced in the fixed facility by the AC magnetic field generated by the data carrier is synchronously rectified by the synchronizing signal controlled by the synchronization signal generating unit in the previous period. The AC magnetic fields received from the data carriers are in phase in general, and the induced electromotive force, which is an error component generated between multiple fixed facilities, is also in phase in general, and the phase of the AC field of the former data carrier and the latter Since it is different from the phase of the induced electromotive force of the Only the rear signal can be detected, and the synchronization signal is supplied to the other fixed facilities by the insulation means that is DC-insulated from the synchronization signal generation means built in the specific fixed facility. Even if a lightning strike occurs, the electric shock will occur only in the fixed facility and not in other fixed facilities. Further, since the power supply of the synchronizing signal generation means is supplied by two or more means, even if the supply of one is stopped, the operation is ensured by the other power supply, so that the supply of the synchronizing signal is maintained and all the plurality of fixed facilities are operated. It does not stop functioning. This is extremely useful when installed outdoors, for example.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a voltage-current distribution diagram for explaining the operation principle of the present invention.

FIG. 3 is a circuit block diagram showing an embodiment of an electromagnetic coupling type data carrier used in the data carrier system of the present invention.

FIG. 4 is a waveform diagram for explaining the embodiment shown in FIG.

FIG. 5 is a circuit diagram showing a first more specific embodiment of the present invention.

FIG. 6 is a power supply circuit diagram for driving the synchronizing signal generating means of the present invention.

FIG. 7 is a block diagram showing a method of connecting a plurality of fixed facilities in the data carrier system of the present invention.

FIG. 8 is a block diagram showing a method of connecting a plurality of fixed facilities in the data carrier system of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 oscillator 2 switch 3 modulation circuit 4 antenna drive circuit 5 current-voltage converter 6 antenna 7 voltage adjustment circuit 8 subtraction circuit 9 amplification circuit 10 synchronous rectification circuit 11 phase adjustment circuit 12 low-pass filter 13 differentiating circuit 14 gate circuit 15 waveform shaping circuit 16 Data carrier 17 Information processing circuit 18 Insulation means 19 DC power supply 20 Battery 21 Switch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiaki Moritsuka 2-24 Himonya, Meguro-ku, Tokyo Inside Olivetti Co., Ltd. Japan (72) Hiromitsu Arai 2-24-24 Himonya, Meguro-ku, Tokyo Japan Inside Olivetti Co., Ltd. (72) Inventor Takashi Omura 2-24, Himonya, Meguro-ku, Tokyo Inside Olivetti Co., Ltd. Japan (72) Innovator Yasunobu Nojiri 2-24, Himonya, Meguro-ku, Tokyo Inside Olivetti Co., Ltd. Japan

Claims (2)

[Claims] 1. A non-powered electromagnetically coupled data carrier and a fixed facility for bidirectional data communication between the data carrier, for transmitting power and data from the fixed facility to the data carrier. In order to make the frequency and phase of the generated AC magnetic field the same between multiple fixed facilities, in a data carrier system that supplies the synchronization signal from the synchronization signal generating means built in a specific fixed facility to other fixed facilities. A data carrier system, characterized in that a synchronizing signal is transmitted from a synchronizing signal generating means built in the specific fixed facility to another fixed facility through an insulating means which is galvanically isolated. 2. The data carrier system according to claim 1, wherein the synchronization signal generating means built in the specific fixed facility is driven by at least two or more different power sources.