FR2636188A1 - RADIO TRANSPONDER APPARATUS FOR TRANSPONDER SYSTEM - Google Patents

Abstract

The invention relates to a radio transponder apparatus in which a rectifier 11 converts the radio energy received into direct current electrical power intended to drive a response logic circuit. According to the invention, a voltage comparator 21 compares the output voltage of the rectifier 11 with a minimum operating voltage. And a control device 20 is actuated by the signal from the voltage comparator 21 so as to actuate the response logic circuit 12 only when the operating conditions are favorable. The invention applies in particular to identification cards used on product manufacturing lines.

Description

The subject of the present invention is a radio transponder apparatus

  part of a transponder system enabling a rectifier to convert a received radio wave into a DC current so as to use the power of the current as a power source

  supply for a logic response circuit.

  In recent years, the following transponder system has been proposed. In this transponder system a radio transponder apparatus is carried by a user or is attached to a moving unit. For example, the own data of the user or the unit that is moving are stored in the radio transponder apparatus. An interrogation signal is transmitted from a fixed radio interrogation apparatus to the radio transponder apparatus using a micrometer wave, and the radio transponder apparatus which receives the interrogation signal transmits a response signal specific to the radio transponder apparatus. the radio interrogation apparatus using the micrometer wave. The radio interrogation apparatus verifies the received response signal by own means, and in this way the moving user or unit can be identified. In accordance with the personal data stored in the radio transponder apparatus, the radio transponder apparatus may be used as an identification card or as a driving license. On the other hand in the case for example of a manufacturing plant producing various types of products in small quantities, a radio transponder apparatus which stores specification data is attached a semi-finished product on a production line. If the specification is interrogated from a fixed radio interrogator interrogating the radio transponder apparatus during each process, and if an operation is performed in accordance with this specification, the radio transponder apparatus may be used as a Instruction of

electronic specification.

  When the radio transponder apparatus is used in the identification cards or in the driving licenses mentioned above, there is a disadvantage if the driving power is supplied from an alternative commercial power source and this in function transportation or movement. If the driving power is provided by a battery, a light and small radio transponder apparatus having

  a long life can not be made.

  A technique for allowing a radio transponder apparatus to receive a micrometer wave transmitted from an external radio interrogation apparatus to the radio transponder apparatus enabling a rectifier to convert the received radio wave into a radio frequency power. direct current, and using energy as a power source for drive or power for a logic circuit is disclosed in Japanese Patent Application Publication (Kokai) No. 56140486 and 63-54023. The conventional system comprising a radio transponder apparatus and a

  radio interrogation device described in the documents

  mentioned above will now be briefly described in making

  reference to the block diagram of Figure 1.

  Referring to FIG. 1, a radio interrogation apparatus 1 comprises a power transmitter 2, and an unmodulated energy wave f1 is transmitted from an antenna 3 to a radio transponder apparatus 4. interrogation apparatus 1 further comprises an interrogation logic 5, and an interrogation signal is sent from the interrogation logic 5 to an interrogation transmitter 6. The interrogation signal is then transmitted to from the interrogation transmitter 6 & the radio transponder apparatus 4 through an antenna 7 as f2 of the interrogation signal. In addition, the radio interrogation apparatus 1 comprises an antenna 8 for receiving a wave f3 forming the response signal transmitted from the radio transponder apparatus 4. The response signal is demodulated from the wave f3 of the received response signal. by the antenna 8 using a response receiver 9, and the demodulated signal is supplied to the interrogation logic circuit 5. In the interrogation logic circuit 5 it is discriminated whether the response signal from the radio transponder apparatus 4 is optimal with respect to the transmitted interrogation signal, and then, if optimal, an operating signal or the like is output to perform a response signal response operation. The radio transponder apparatus 4 comprises an antenna 10 for receiving the wave of energy transmitted from the antenna 3. The wave of energy received by the antenna 10 is converted into a DC power by a rectifier 11, and is provided at a terminal of a power or supply source of a response logic circuit 12, and is used as a driving power source. In addition, an antenna 13 is arranged to receive the wave f2 forming the interrogation signal transmitted from the antenna 7. The interrogation signal is demodulated from the wave f1 of the interrogation signal. received by the antenna 13 by means of an interrogation receiver 14, and the demodulated signal is supplied to the response logic circuit 12. In addition, a response signal transmitted from the response logic circuit 12 is supplied to the transmitter 15 of the response, and it is transmitted from an antenna 16 to the radio interrogation apparatus 1 as wave f3 forming the response signal. The logic response circuit 12 suitably performs an arithmetic operation in accordance with the memory data in response to the interrogation signal so as to provide the response signal, or the memory content is updated to

response to the interrogation signal.

  In the aforementioned radio transponder apparatus 4, when the interrogation distance of the radio apparatus 1 increases, the intensity of the electric field of the energy wave fl that can be received by the radio transponder apparatus 4 weakens. The capacity of the DC power signal from the rectifier 11 also decreases, and a minimum voltage enabling optimal operation of the response logic 12 can not be obtained. Thus, when the voltage required for optimal operation is not provided and the logic response circuit 12 is actuated, an operating error can easily occur. In response to an erroneous arithmetic operation, an erroneous response signal may be delivered, or the contents of the memory may be incorrectly updated. In particular, when the contents of the memory are incorrectly updated, an erroneous response signal is delivered in accordance with the erroneous contents of the memory even though the circuit is

  normally operated after the update operation.

  An object of the invention is therefore to provide a radio transponder apparatus for a transponder system which

  operates correctly in response to a received radio wave.

  Another object of the present invention is to provide a radio transponder apparatus for a transponder system allowing a visual or audible confirmation

  that the device can work or works properly.

  In order to achieve the mentioned objects, in accordance with the present invention, there is provided a radio transponder apparatus enabling a rectifier to convert a received radio wave into a DC current intensity in order to use the supplied power as a power source. drive for a response logic circuit, comprising a voltage comparator for comparing an output voltage from the rectifier with a predetermined minimum operating voltage, and a controlled control device in response to a signal from the voltage comparator, the control device activating one of the components which constitutes the apparatus so as to start a response operation when the output voltage from the rectifier equals the minimum operating voltage or is greater. One of the components is, for example, a response logic circuit. When the output voltage from the rectifier is equal to the minimum operating voltage or is greater, the control device delivers a DC power to the logic response to

  through a switch on the output side of the rectifier.

  Another of these components is a response transmission system. More specifically, the control device may be installed in such a way that the response signal from the response logic is supplied to the response transmitter through the switch when the output voltage from the rectifier is equal to the minimum operating voltage or is higher. The control device may be installed such that an alarm signal from an alarm signal generator is supplied to the response transmitter when the output voltage from the rectifier is less than

the minimum operating voltage.

  The control device may be installed in such a way that the interrogation signal from the interrogation receiver is delivered to the response logic circuit through the switch when the output voltage from the rectifier is equal to the minimum operating voltage or is greater than . In addition, operation display means controlled in response to the signal from the voltage comparator may be installed and driven when the output voltage from the rectifier is equal to the minimum operating voltage or is greater, or conversely is

  less than this minimum value of operating voltage.

  In the accompanying drawings Fig. 1 is a block diagram showing a conventional system comprising a radio transponder apparatus and a radio interrogation apparatus; Fig. 2 is a block diagram showing a radio transponder apparatus according to an embodiment of the present invention; and Figure 3 shows schematically a circuit illustrating a detailed arrangement of a voltage comparator that can be used in Figure 2; Fig. 4 is a block diagram showing a radio transponder apparatus according to another embodiment of the present invention;

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  FIG. 5 is a block diagram showing a radio transponder apparatus according to another embodiment of FIG.

  still carrying out the present invention.

  Embodiments of the present invention will now be described with reference to Figs. 2 and 3. Fig. 2 is a block diagram showing a radio transponder apparatus according to an embodiment of the present invention, and Fig. 3 schematically shows a circuit illustrating a detailed arrangement of a voltage comparator used in FIG. 2. The reference numerals used in FIGS. 2 and 3 correspond to the same elements

circuit than those of Figure 1.

  The radio transponder apparatus illustrated in FIG. 1 comprises an antenna 10 for receiving a wave f1 of energy transmitted from a radio interrogation apparatus. The energy wave fi received by the antenna 10 is converted into a DC current through a rectifier 11. The converted power is supplied to the terminal of the power source or power supply terminal. a logic response circuit 12 through a control device 20 of the switch power source, and is used

  as an electrical power source.

  An output signal from the rectifier 11 is supplied to the voltage comparator 21 and is compared with a predetermined minimum operating voltage. The result of the comparison is provided to operation display means 22. For example, when the apparatus is in operation, a lamp is lit, or an indication

  suitable for visual or audible operation is provided.

  When the signal power from the rectifier 11 is less than the minimum operating voltage, a visual or audible indication of operation whose mode is

  different from that of the above-mentioned

  mentioned can be obtained. Note that the switch used as the power source control device is of a type having a control terminal. The operation display means 22 are constituted for example by a LED (light diode) or by an audible alarm. An antenna 13 for receiving a wave f2 forming the interrogation signal transmitted from the radio interrogation apparatus is provided. The interrogation signal is demodulated from the fl ow of the interrogation signal received by the antenna 13 by means of an interrogation receiver 14, and the signal is supplied to the response logic circuit 12. In addition, a response signal from the response logic circuit 12 is supplied to the response transmitter 15, and is transmitted from an antenna to the radio interrogation apparatus as the waveform f3 forming the response signal. The logic response circuit 12 conveniently performs an arithmetic operation in accordance with the memory data in response to the interrogation signal so as to provide the response signal, or the contents of the memory are updated to

response to the interrogation signal.

  The radio transponder apparatus of FIG. 2 is different from the transponder radio apparatus 4 of FIG. 1 as follows. In FIG. 2 a DC power signal from the rectifier 11 is supplied to the electrical power supply terminal of the response logic circuit 12 and this through the power source of the control device 20, and the signal is supplied to the voltage comparator 21. In the voltage comparator 21, the output voltage from the rectifier 11 is compared with the predetermined minimum operating voltage, and the resulting signal is supplied to the source control device 20.

  power supply and means 22 for displaying the operation.

  The voltage comparator 21 is installed, as shown in FIG. 3. At the output side of the rectifier 11, a series circuit consisting of a resistor R1 and a Zener diode ZD is grounded in parallel with a series circuit of FIG. resistors R2 and R3. In addition, the voltages divided at the connection point between the resistor R1 and the Zener diode ZD and a connection point located between the resistors R2 and R3 are respectively supplied to the input terminals of a differential amplifier COMP, and a signal from of the output terminal of the differential amplifier COMP is supplied to the control device 20 of the power source and to the

  operating display means 22.

  When the divided voltage obtained by dividing the output voltage from the rectifier 11 by the resistors R2 and R3 is smaller than the Zener voltage of the Zener diode ZD, the differential amplifier COMP delivers a voltage at a level "L" (at the low level), and the device 20 for controlling the power supply is decommissioned. When the output voltage of the rectifier 11 increases and the voltage divided by the resistors R2 and R3 becomes greater than the voltage of the Zener diode, the output signal from the differential amplifier COMP is inverted at the "H" level (at high level). The control device 20 of the power source is then put into operation, and a DC signal from the rectifier 11 is supplied to the response logic circuit 12 through the power source control device 20 as a drive power source. The operation display means 22 causes the light diode to be turned on or to supply the alarm signal so as to produce an audible signal in response to a power supply located at the "H" level coming from the differential amplifier. COMP. When the output voltage from the rectifier 11 increases to reach the minimum voltage to properly operate the logic 12 response or is at a higher voltage, the control device 20 of the power source is switched from its state where it was out of service in his condition where he is on duty. The minimum operating voltage as a reference voltage for the switching operation is suitably determined in advance in accordance with the Zener diode voltage ZD and the divider ratio of the

resistors R2 and R3.

  With such an arrangement, since the power supply is supplied from the rectifier 11 to a logic response circuit 12 when the output voltage from the rectifier 11 is equal to the minimum operating voltage or is greater, an operating error due to insufficient supply voltage can not occur. Furthermore, given the display operation performed by the display means 22, it can be easy to determine whether the radio transponder apparatus 4 is located within the electric field intensity range which allows optimal operation in response to a query from

  of the radio interrogation device 1.

  The operation display means 22 may be arranged as follows. When the output voltage from the rectifier 11 is lower than the minimum operating voltage and does not allow optimal operation of the response logic circuit 12, but this voltage is greater than "0", the light-emitting diode is lit or the signal of sound alarm is activated. As a result, it can be determined that the radio transponder apparatus is located beyond the interval in which optimal intensity is produced.

of the electric field.

  Fig. 4 is a block diagram showing a radio transponder apparatus designed according to another embodiment of the invention. The same reference numbers in FIG. 4 designate the same elements as in FIGS.

  and 2, and a repetition of the description will not be

made.

  The radio transponder apparatus of Fig. 4 differs from the transponder radio apparatus 4 shown in Fig. 1 as follows. In Fig. 4 a response signal transmitted from the response logic 12 is provided to a response transmitter 15 through a response signal control device, and an output voltage from the

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  voltage comparator 21 is provided to the response logic circuit 12 and an alarm signal generator 31. In addition, an alarm signal from the alarm signal generator 31 is supplied to the response signal control device 30. The response signal control device 30 is of the two-input type with a control terminal. As functions of the response signal control device, a response signal from the response logic circuit 12 is supplied to a link terminal, the alarm signal from the alarm signal generator 31 is supplied to the other link terminal, and a signal of the common link terminal is provided to the response transmitter. Further, in the response signal control device 30, when a signal from the voltage comparator 21 is set to the "H" level, a link terminal for receiving the response signal is connected to the common terminal, as indicated 4. When the voltage from the voltage comparator 21 is adjusted to "L" level, the other connection terminal, to receive the alarm signal, is connected to the common terminal as indicated. by the dashed line in FIG. 4. The alarm signal generator 31 generates an alarm signal when the signal from the voltage comparator 21 is adjusted to the "L" level. The alarm signal generator 31 and the response transmitter 15 perform an optimal operation even if the operating voltage is lower than the minimum operating voltage of the

circuit 12 response logic.

  With such an arrangement, when the output voltage from the rectifier 11 is less than the minimum operating voltage, and is less than a voltage that allows the optimal operation of the response logic circuit 12, an alarm signal is provided to the transmitter 15 in response to the response signal which may be an erroneous signal, and is transmitted to the radio interrogation apparatus 1 as a response signal waveform f3. The radio interrogation apparatus 1 receives the alarm signal to readily determine that the radio transponder apparatus 4 is located beyond

  the interval of the optimum electric field intensity.

  It should be noted that the alarm signal generator 31 may be omitted so as to transmit neither an alarm signal nor a response signal when an output voltage from the rectifier 11 is below the minimum operating voltage. In this case the radio interrogation apparatus 1 can determine that the radio transponder apparatus 4 is located outside the optimum electric field strength interval since the response signal is not supplied from the radio transponder apparatus 4. Regardless of the presence or absence of the alarm signal generator 31, even if the response signal is not transmitted and the logic response circuit 12 is erroneously operated by following a low drive voltage when the output voltage from the rectifier 11 is lower than the minimum operating voltage, no response signal

wrong can not be transmitted.

  FIG. 5 is a block diagram showing a radio transponder apparatus according to another embodiment of FIG.

  still carrying out the present invention.

  The same reference numerals designate in FIG. 5 the same elements as those of FIGS. 2 and 1, and a

  repetitive description of these elements will not be made.

  The radio transponder apparatus shown in the figure differs from the radio transponder apparatus of Fig. 4 and that shown in Fig. 1 in the following. In Fig. 5 an interrogation signal from the interrogation receiver 14 is provided to a response logic circuit 12 through a polling signal control device 40 serving as a switch with a control terminal. A sub-carrier of a wave f2 of the interrogation signal is converted into direct current by a rectifier 11. The converted power is supplied to the supply terminal of a response logic circuit 12 and is supplied to a voltage comparator 21 . In addition, a control device 40 of the interrogation signal is monitored in response to the output signal from the voltage comparator 21. When the output signal from the voltage comparator 21 is set to a "H" level, the device for controlling the interrogation signal 40 is put into service and provides an interrogation signal to the circuit

response logic 12.

  With such an arrangement, when the signal from the rectifier 40 is less than the minimum operating voltage, the interrogation signal is not supplied to the response logic circuit 12. As a result, an erroneous operation for updating the content of the memory caused by too low a drive voltage can be prevented. The embodiment illustrated in FIG. 5 is suitable for the case where the energy wave fl is not transmitted to the radio interrogation apparatus 1, but it is only the f2 wave of the

  interrogation signal that is transmitted.

  Note that the energy wave f1 is received and converted to DC power in the embodiments illustrated in FIGS. 2 and 4 and in the prior art illustrated in FIG. 1, and that the subcarrier of FIG. The interrogation signal wave f2 obtained by the interrogation receiver 14 through the antenna 13 is converted to DC power and is used as a power supply source for the circuit 12.

  response logic in the embodiment illustrated in FIG. 5.

  However, the received radio wave to be converted to continuous power and used as a drive power source is not limited, of course. Given the above provisions

  described, the effects mentioned below are achieved.

  When an intensity of the electric field of the received radio wave is low, and the output voltage from the rectifier is less than the minimum operating voltage, a DC power supply is not supplied to the response logic circuit. Since the response logic circuit is not actuated, a malfunction due to - 13

  at too low a drive voltage can occur.

  For this reason, in the radio transponder apparatus according to the present invention, the transmission of a response signal and the updating of the contents of a memory are performed only when the apparatus is located within an intensity range of the electric field which allows the optimal operation of the apparatus providing communication

high reliability.

  Assume that the intensity of the electric field of the received radio wave is small and that the output voltage of the rectifier is lower than the minimum operating voltage. If the response signal is not transmitted, the transmission of an erroneous response signal can be prevented, which improves the reliability of the communication. If an alarm signal is transmitted when the response signal is not transmitted, it can be readily determined from the radio interrogation apparatus side that the radio transponder apparatus is located beyond the range of intensity of the electric field that allows a

optimal operation.

  If the transmission of the interrogation signal to the response logic circuit is prevented when the signal from the rectifier is below the required minimum operating voltage, an erroneous update of the contents of the memory in response to a interrogation signal can occur. be

prevented.

  Furthermore, when the operation display means show whether the output voltage of the rectifier reaches the minimum operating voltage or exceeds it, it can be easily determined whether the radio transponder apparatus is located inside or outside. the intensity range of the electric field which allows the optimal operation of the device. If necessary, the radio transponder apparatus may be brought closer to the radio interrogation apparatus.

Claims (8)

  A radio transponder apparatus of a transponder system that allows a rectifier (11) to convert a received radio wave into a direct current so as to use the electrical power as the drive power source for a response logic ( 12), characterized in that it comprises a voltage comparator (21) for comparing an output voltage from said rectifier (11) with a predetermined minimum operating voltage, and a control device (20) controlled in response to a signal from said voltage comparator (21), said control device activating one of the components which constitute said radio transponder apparatus so as to start a response operation when the output voltage from said rectifier (11) is not lower than to the tension minimal operative procedure required.   Apparatus according to claim 1 characterized in that one of said components is a response logic circuit (12), and said control device (20) comprises means for providing a DC power supply which is a signal from said rectifier output to said response logic as a driving power source in response to a signal from said voltage comparator (21) obtained when an output voltage from said rectifier (11) is not   less than said minimum operating voltage.   Apparatus according to claim 1 characterized in that one of said components is a response transmission system, and said control device (20) comprises means for connecting an output side of said response logic circuit to said transmission system response (15) in response to a signal from said voltage comparator obtained when the output voltage from said rectifier   is not less than said minimum operating voltage.   4. Apparatus according to claim 3 characterized in that it further comprises an alarm signal generator (31) characterized in that said control device (30) comprises means for providing an alarm signal from said generator of an alarm signal (31) to said response transmission system (15) when the output voltage from said rectifier (11) is less than the voltage minimal operative procedure.   Apparatus according to claim 1, further comprising an interrogation receiver (14) for receiving an interrogation, characterized in that one of said components is a response logic circuit (12), and said control device (40) receives an interrogation signal from said interrogation receiver towards said response logic when the output voltage from said rectifier is not lower than said operating voltage minimal.   Apparatus according to claim 1 characterized in that one of said components is constituted by operation display means (22), and said control device (20) supplies said operation display means when the voltage of said output from said rectifier is not less than or less than minimal operating voltage.   The apparatus of claim 1 further comprising an interrogation receiver (14) for receiving an interrogation signal wave from said radio interrogation apparatus, characterized in that said rectifier converts a subcarrier of the signal wave interrogation a direct current.   Apparatus according to claim 1 further comprising means for receiving an energy wave from said radio interrogation apparatus, characterized in that said rectifier (11) converts the energy wave into a   DC electrical current.