JP3557342B2 - Communications system - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is an improvement of a communication system configured such that a slave station receives energy propagation emitted by a master station and communicates with the master station by obtaining power for operating the slave station from the received energy propagation. It is about.
[0002]
[Prior art]
FIG. 6 is a block diagram showing an example of this type of conventional communication system. The IC card read / write device 2 as a master station is a read / write device for the non-contact type IC card 8 as a slave station, and is built in the non-contact type IC card 8 by performing wireless communication with the non-contact type IC card 8. A device that reads and writes the contents of a memory that is connected to a higher-level device 1 such as a personal computer that processes those stored contents, and operates according to instructions from the higher-level device 1. The control circuit 3 includes a transmission circuit 3A and a reception circuit 3B, and also performs transmission and reception of data, respectively. Similarly, the control circuit 7 in the non-contact type IC card 8 also includes a memory, a transmission circuit, and a reception circuit (all not shown).
[0003]
The electric power for operating the non-contact type IC card 8 is received when the non-contact type IC card 8 approaches the IC card read / write device 2 (for example, a distance of several cm) from the IC card read / write device 2, It is configured to operate by receiving power from the received radio wave power.
[0004]
FIG. 7 shows a circuit example of the power supply circuit 6 shown in FIG. In FIG. 7, a radio wave emitted from an antenna coil 4 for power transmission and data transmission / reception of the IC card read / write device 2 is received by a resonance circuit 13 including an antenna coil 5 for power reception and data transmission / reception and a capacitor 14. The obtained voltage is rectified by the diode 9 and stored in the capacitor 10. The voltage of the capacitor 10 is determined by the voltage monitoring circuit 12 to determine whether the voltage is at a voltage level at which the control circuit 7 can operate. When determining that the voltage level is operable, the voltage monitoring circuit 12 switches on the transistor 11 to supply power to the control circuit 7. As a result, the control circuit 7 starts operating and can communicate with the IC card read / write device 2.
[0005]
FIG. 8 is a sectional view showing a reading position of the non-contact type IC card 8. The non-contact type IC card 8 moves to the position 8a, the position 8b, and the position 8c, and passes through the power supply area 15 and its vicinity. The power supply available area 15 indicates an area where power can be supplied to the non-contact type IC card 8 by radio waves emitted from the antenna coil 4 built in the IC card read / write device 2. When the non-contact type IC card 8 moves from the position 8a to the position 8b, the voltage stored in the capacitor 10 increases. When this voltage reaches a specified voltage level, the voltage monitoring circuit 12 turns on the transistor 11, and power is supplied from the capacitor 10 to the control circuit 7 of the non-contact IC card 8. The control circuit 7 starts operating and starts communication with the IC card read / write device 2.
[0006]
In addition, Japanese Patent Application Laid-Open No. 8-69513 has proposed a power supply for a non-contact type IC card that transmits and receives data using radio waves. In this publication, in order to combine the advantages of a card with a built-in battery and a card of a batteryless type, extend the life of the battery and hence the life of the card, and obtain a long communication distance, the received radio wave is strong. In such a case, a capacitor that is charged by obtaining electric power from a received radio wave is used as a power source, and a primary battery is used as a power source when the received radio wave is weak.
[0007]
[Problems to be solved by the invention]
Radio waves emitted from the antenna coil 4 of the IC card reader / writer 2 are emitted in all directions, and a part of the radio waves is received by the antenna coil 5 of the non-contact type IC card 8, so that the power transmission efficiency is very poor. It has become. Further, since it is unknown when the non-contact type IC card 8 can be approached to the IC card read / write device 2, the antenna coil 4 of the IC card read / write device 2 must always output radio waves. There is a problem that the IC card read / write device 2 consumes power even when it is not communicating with the IC card.
[0008]
Further, as shown in FIG. 8, after the non-contact IC card 8 enters the power supply available area 15 and starts communication with the IC card read / write device 2, the non-contact IC card 8 moves to the position 8c. As a result, the voltage of the capacitor 10 in FIG. 7 decreases, and the power supply to the control circuit 7 is cut off by the voltage monitoring circuit 12. Therefore, when the non-contact type IC card 8 passes through the power supply area 15 and its vicinity, if the power supply area 15 is small, the control circuit 7 can operate once but cannot operate immediately. And communication is interrupted on the way. At this time, if the writing operation is being performed on the internal memory of the non-contact type IC card 8, the writing is completed in the middle and there is a serious problem in reliability.
[0009]
Japanese Patent Application Laid-Open No. 8-69513 proposes that a non-contact IC card becomes large due to the use of a primary battery, and the usage of the primary battery must be considered in consideration of the life of the primary battery. There is a problem. .
(Object of the invention)
An object of the present invention is such that a slave station receives energy propagation emitted from a master station, obtains power for operating the slave station from the received energy propagation, and performs communication with the master station for reading and writing data. It is an object of the present invention to provide a communication system capable of suppressing power consumption of a master station and improving communication reliability in the communication system configured as described above.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a slave station that receives energy propagation emitted from a master station, obtains power for operating the slave station from the received energy propagation, and obtains power from the master station and data. In a communication system configured to perform communication for reading and writing, when the master station starts communicating with the slave station, the strength of energy propagation emitted by the master station is set to be greater than before the start of communication. When the master station finishes reading / writing data from / to the slave station, the strength of energy propagation emitted by the master station is made smaller than the strength at the start of communication .
[0011]
In the present invention, "energy propagation" is used as a term including radio waves, electrostatic induction, and electromagnetic induction.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
The entire communication system according to an embodiment of the present invention is the same as the conventional communication system shown in FIG. 6, in which an IC card read / write device 2 is used as a master station and a non-contact IC card 8 is used as a slave station. . As the usage of the non-contact type IC card 8, it is assumed that a person holds the non-contact type IC card 8 over the IC card read / write device 2. Note that radio waves are used as a form of energy propagation.
[0013]
FIG. 1 is a block diagram showing a part of a control circuit 3 of an IC card read / write device 2 according to an embodiment of the present invention, in which power transmission and data transmission are configured by the same antenna.
[0014]
With the data output from the data generation circuit 21, the carrier wave of the oscillation circuit 22 is modulated by the modulation circuit 23 and amplified by the low power amplification circuit 24 or the high power amplification circuit 25, and the low power transmission antenna coil 26, The high power transmission antenna coil 27 emits the radio waves to the outside. The low-power amplifier circuit 24 and the high-power amplifier circuit 25 do not operate at the same time, and one of them is selected and operated by the switching circuit 28 as described later.
[0015]
Radio waves emitted by the non-contact type IC card 8 are received by the receiving antenna coil 29, amplified by the amplifier circuit 30, and demodulated by the demodulation circuit 31. In this manner, the data read from the non-contact type IC card 8 is processed by the data processing circuit 32, and the switching circuit 28 and the data generation circuit 21 are controlled according to the processing result.
[0016]
FIG. 2 is an external view showing an example of the arrangement of the low power transmission antenna coil 26 and the high power transmission antenna coil 27. The high power transmission antenna coil 27 is formed concentrically outside the low power transmission antenna coil 26. Are located. The illustration of the receiving antenna coil 29 is omitted.
[0017]
FIG. 3 is a flowchart showing a switching operation of the low power amplifier circuit 24 and the high power amplifier circuit 25 by the switching circuit 28 and the like. When the power of the IC card reading and writing apparatus 2 at step 1 is turned on, without operating the high power amplifier circuit 25, thereby operating only amplifying circuit 24 for low power. Thereby, as shown in FIG. 4, the power supplyable area 15a is configured. Thereafter, when the non-contact IC card 8 approaches and moves to the position 8b that enters the power supplyable area 15a, the non-contact IC card 8 receives power supply from the IC card read / write device 2 as described above, and Communication with the card read / write device 2 is started. At the start of the communication, the non-contact type IC card 8 emits a radio wave of a control code indicating that the communication is enabled, so that the IC card read / write device 2 receives the radio wave of the control code and performs data processing. The circuit 32 identifies the start of communication and informs the switching circuit 28 of it. The switching circuit 28 determines in step 3 that the non-contact IC card 8 has approached, stops the operation of the low-power amplifier circuit 24 in step 4, and operates the high-power amplifier circuit 25. As a result, as shown in FIG. 4, the power supply area 15a extends to the power supply area 15b, and communication at the position 8c where communication was impossible in the past becomes possible.
[0018]
Step 5 The data processing circuit 32 in the read and write operation of data required with the non-contact type IC card 8, when determining the completion of the write operation in step 6, the process returns to step 2 again, a high power the operation of the amplifier circuit 25 is stopped, to operate the amplifying circuit 24 for low power. This returns to the initial state and prepares for communication with the next non-contact type IC card. Figure 5 is a diagram showing the transition of power consumption when the power consumption W when the communication time T ₁ and the communication time T ₂ are is larger than the power consumption W ₀ when not communicating.
[0019]
As described above, even if the non-contact type IC card 8 moves at a considerable speed, the time for supplying power to the non-contact type IC card 8 can be made relatively long as compared with the related art, so that reading and writing can be performed. Can be reliably performed, and the reliability can be improved. Further, it is possible to reduce the power consumption W ₀ when not communicating, it can be energy saving type.
[0020]
In the present embodiment, an example is described in which the antenna coil for power transmission or power reception and the antenna coil for data transmission and reception are shared, but the antenna coils for power transmission or power reception and data transmission and reception are separately provided. Is also good.
[0021]
Further, although an IC card read / write device is used as a master station and a non-contact IC card is used as a slave station, the present invention is not limited to this.
[0022]
Although transmission and reception of electric power by radio waves has been described as an embodiment, it is apparent that equivalent effects can be obtained by using transmission and reception of electric power by electrostatic induction or electromagnetic induction.
[0023]
As an application of the present invention, an automatic ticket gate and the like are suitable.
[0024]
【The invention's effect】
As described above, according to the present invention, the slave station receives the energy propagation emitted from the master station, obtains power for operating the slave station from the received energy propagation, and obtains power of the master station and data. In a communication system configured to perform communication for reading and writing, when the master station starts communicating with the slave station, the strength of energy propagation emitted by the master station is set to be greater than before the start of communication. Since the strength of energy propagation emitted by the master station when the master station finishes reading and writing data to the slave station is made smaller than the strength at the start of communication , the power consumption of the master station is reduced. It is possible to suppress the communication and improve the reliability of communication.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a part of a control circuit of an IC card read / write device of a communication system according to an embodiment of the present invention.
FIG. 2 is a plan view showing an example of an arrangement of a low-power transmitting antenna coil and a high-power transmitting antenna coil of FIG. 1;
FIG. 3 is a flowchart showing a switching operation and the like by the switching circuit of FIG. 1;
FIG. 4 is a diagram illustrating a change in an area where power can be supplied by an IC card read / write device of a communication system according to an embodiment of the present invention and a movement locus of a non-contact type IC card.
FIG. 5 is a diagram showing a transition of power consumption of the IC card read / write device of the communication system according to the embodiment of the present invention.
FIG. 6 is a block diagram illustrating an outline of a communication system commonly used in a conventional type and one embodiment of the present invention.
FIG. 7 is a circuit diagram illustrating an example of a power supply circuit of FIG. 6;
FIG. 8 is a diagram showing a movement locus of a non-contact type IC card with respect to an IC card reading / writing device of a conventional communication system.
[Explanation of symbols]
2 IC read / write device 3 control circuit 4 antenna coil 5 antenna coil 6 power supply circuit 7 control circuit 8 non-contact type IC card 15a, 15b power supply available area 21 data generation circuit 22 oscillation circuit 24 low power amplification circuit 27 high power amplification Circuit 26 Low power transmission antenna coil 27 High power transmission antenna coil 28 Switching circuit 29 Receiving antenna coil 30 Amplification circuit 31 Demodulation circuit 32 Data processing circuit

Claims (2)

The slave station is configured to receive the energy propagation emitted from the master station, obtain power for operating the slave station from the received energy propagation, and perform communication with the master station for reading and writing data . In the communication system, when the master station starts communication with the slave station, the intensity of energy propagation emitted by the master station is set to be greater than before the start of communication, and the master station reads and writes data from and to the slave station. The communication system, wherein the intensity of energy propagation emitted by the master station when the communication is completed is made smaller than the intensity at the start of communication. 2. The communication system according to claim 1, wherein radio waves are used as energy propagation, the slave station is a non-contact IC card without a battery, and the master station is an IC card reading / writing device.

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