JPH0447389A - Contactless ic card - Google Patents

Abstract

PURPOSE:To surely perform communication between an IC card and an external device by providing a detecting circuit which detects an input level and a means which monitors the input level to permit or inhibit the communication with the external device. CONSTITUTION:A detecting circuit 10 consists of a coil antenna, a smoothing circuit consisting of a diode, a capacitor, and a resistance, and a Schmitt trigger circuit; and when an input signal higher than a prescribed level is continuously applied to the coil, the output of the detecting circuit 10 rises from the low level to the high level, and a trigger is applied by this rise to start an IC card. When the fall from the high level to the low level is detected, an interrupt signal is generated to transfer the processing control of a CPU 11 to an interrupt routine; and if it is not returned to the high level within a prescribed time, it is transferred to an error processing routine. Thus, erroneous data is not written to improve the reliability of communication data even in the case of going-away from the communication range during communication or hindrance of communication due to obstacles.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a book related to a contactless IC card that has a built-in battery and performs data communication using radio waves.

l.

8. [Prior Art] FIG. 6 is a block diagram showing the structure of a conventional non-contact IC card. The 0PTJll that controls the entire card is connected via the bus 18i to the program memory RoMlg, the data memory RAM 18, and the input/output circuit 14 that performs parallel/serial conversion and serial/parallel conversion.The battery 17 is connected as an Ot source. Built-in.

The data output from the input/output circuit 14 is transmitted to the modulation/demodulation circuit @15.
The signal is modulated by the transmitting circuit 19, which drives the antenna 16, and outputs it as a radio wave. Further, the signal received by the antenna 16 is amplified by the receiving circuit 2o, converted to a logic level, and then demodulated by the 9 demodulation circuit 15 and input/output circuit 14. It is provided to the CPU II via path 18 for processing.

Next, we will explain the previous version of the contactless IC card. battery 1
Normally, when the non-contact IC card incorporating 7 is not communicating with the sensor, it is in a standby state by stopping the bias current of the receiving circuit 11Q and stopping the oscillating circuit 1 (included in the oscillating circuit C0P011). Here, a trigger signal is input from the sensor side to activate the card, and the card is activated by antenna 1.
When 6 receives this and sends a trigger signal 5・C to 0PUII, (!The oscillation circuit in PUII starts operating, the CPU starts operating, and according to the program, a bias current flows through the receiving circuit to transmit and receive data from the sensor. When communication with the sensor is completed, %C!PUII is ready to receive F!Ilrg
o's bias current is stopped, the oscillation circuit is stopped, and the card is placed in a standby state. Consumption of the battery 17 was suppressed by such a method.

In addition, as a means to ensure that the input radio waves to the card are at an appropriate level, the sensor side transmits the signal reception level to the card, and the card transmits the signal reception level to the card. A method is disclosed in which the level is adjusted, and a method in which the card side notifies the sensor side of the reception level and the sensor adjusts the transmission level.

[Problem to be solved by the invention]

Since the conventional IC card was configured as described above,
When the IC card receives a trigger signal, it starts communicating with the sensor, but the distance between the IC card and the sensor is
cf, there is no guarantee that mutual transmission and reception levels are maintained properly during communication, and there is also a drawback that it is vulnerable to obstacles. As means for ensuring the transmission and reception level, for example, in the method shown in Japanese Patent Application Laid-Open No. 68-284692 and Japanese Patent Application Laid-Open No. 63-199863, the transmission and reception level is appropriate only when the sensor or card sets the transmission level, and the communication There is no guarantee that it will be appropriate throughout the entire time. Also, since it is necessary to control the bias current of the receiving circuit on and off using software, if detailed control is required to reduce battery consumption as much as possible,
I'm afraid there is a problem with the software load increasing.

This invention was made to solve the above-mentioned problems, and it is possible to always ensure that the transmission and reception level between the IC card and the sensor is at an appropriate level, improve the reliability of the transmission and reception data, and reduce the bias current of the reception circuit. Kuraguchi's objective is to obtain a contactless IC card that can perform on/off control using hardware and reduce the software load.

〔assignment? Means to solve]

The contactless IC card according to the present invention is provided with a detection circuit that constantly detects the level of input radio waves as a means to ensure the transmission and reception level, and this detection circuit obtains a trigger signal to activate the IC card, and also generates a transmission permission signal and bias. In addition, if a drop in level is detected during communication, if the level does not return within a predetermined time after all interrupts are applied, it is treated as a communication error and error processing is performed.

[Effect]

The detection circuit in this invention is constituted by a coil antenna, a smoothing circuit consisting of a diode and a capacitor resistor, and a Schmitt trigger circuit. When an input signal of a predetermined value or more is continuously applied to the coil, the output of the detection circuit changes from "L#" to "L".
It rises to 'H'. At this rise, the trigger is applied.
The IC card is activated, the CPU is activated, and when this signal is at the HL level, transmission is permitted, and a bias current is applied to the receiving circuit to enable reception. The XC card will not consume current unless it is close enough to the sensor to be able to communicate completely.
There is no communication.

Also, when a fall from 'H' to 'L' is detected, an interrupt signal is generated and the CPU processing is moved to the interrupt routine, and if it does not return to 6■" within a predetermined time, it will move to the error handling routine. Therefore, even if the user moves away from the communicable range or the communication is obstructed by an obstacle during communication, the reliability of one communication data is significantly improved without writing erroneous data.

[Implementation row]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the structure of a non-contact IC card according to an embodiment of the present invention, which is almost the same as the conventional one except for the detection circuit IO. The difference is the detection circuit 10
In response to the trigger signal of the output 1-c, the oscillation circuit in the CPU 1i starts full operation, and the CPU 11 starts operating.

In addition, the output 1-a of the detection circuit 10 is connected to the bus 18, and can be read by (!PUII) reading a predetermined address (address of the detection circuit register). A bias application signal of 1-(l enters the receiving circuit 20, and this signal controls the bias current of the receiving circuit sO. Also, an interrupt signal of the detection circuit output 1-b enters the receiving circuit 20. Under the control of this signal, CpH1rll moves the processing to the interrupt routine.

Next, details of the detection circuit 10 will be explained using FIGS. 8 through 4. FIG. 2 is a circuit diagram showing a -* embodiment of the detection circuit 10 of FIG. 1. In the figure, Jll and 22ri each constitute an LO resonance circuit with a coil and a capacitor. It is assumed that this resonant frequency is different from that of the data transmitting/receiving antenna 16. The radio wave input from the sensor is this LC
Vibrate the resonant circuit and use it as a diode! 8 performs half-wave rectification, and capacitor 84 smoothes the potential of the signal line MU, but at this time, the resistance! Since power is consumed by the current flowing through l5VCi, unless the LO resonant circuit has an input terminal that is continuously at a predetermined level or higher, the potential at point A will not exceed the threshold voltage of Schmitt circuit g6, so output B will be "L". On the other hand, if there is a continuous input of a predetermined level or higher, the threshold value at point A is exceeded and the output B becomes H". That is, if the input from the sensor is always above a predetermined level, the output B is 1H#, and when it is below the predetermined level, it becomes ゝゝL//. Further, this level can be adjusted by the resistor 25 and the threshold voltage of the Schmitt trigger B6. The side leg signals 1-a-1-c are obtained from output B.

The bias application signal ia is the output B as it is, and this signal applies the bias ti to the receiving circuit to enable reception. Signal 1-a is the output of detection circuit register 28 and is connected to bus 18.

Detection circuit B 8 [This is a 1-bit read-only register. When the CPU II reads a predetermined address, it outputs the value of output B to the bus 18. Trigger signal l・C is C! This is a signal that starts the oscillation of the oscillation circuit in PUI l. When the first output B rises, the trigger circuit s't raises the output to 6". Also, l and C are the oscillation stop signals 2 from CPU l.
- Cleared by aVc. FIG. 3 shows the configuration of the trigger circuit s7. Also, it is the No. 1 1-k) Fi interrupt signal in FIG. 8, and when the falling edge of the output B is detected by the falling edge detection circuit 29, it outputs nH "7" with a length of 7 l pulses of the internal clock of the CPU 11. .Thus, a drop in the input level is detected and the CPU processing t-, II
J Move to the entry routine.

FIG. 4 shows the configuration of the fall detection circuit 89.

The above is the hardware configuration.

Next, regarding the previous IC card sequence, 70 in Figure 5
-Explain using a chart.

If the detection circuit 10 receives an input of a predetermined level or higher in step 41, the trigger signal 1-c rises and starts oscillation in step 48. After this, cpUll begins its preprocessing and enters the data communication and data processing routine of step 48.

At this time, if the input to the detection coil 21 continues to be at a predetermined level or higher, the routine of step 48 is normally terminated, and in step 44, the disbursement is stopped and the process is terminated. However, if the input level decreases during the process, an interrupt routine is executed. (Step 45)
Transfer processing to In the interrupt routine in step 45, the detection circuit register is read out in step 47 a predetermined number of times, and in step 48 it is checked whether the output has returned to SS H" or not.
ia! T.

If the state returns to ``H'', the process proceeds to step 49IC, returns to the original data communication and processing routine, and continues processing. However, if the process does not return even after repeating the predetermined number of times, it branches to step 46 and returns to the error handling routine of step 51. After initializing the data 4° in the IC card to the state before the start of communication and setting an error status, the oscillation is stopped at step 44 and the process ends.

The above is the operation of the IC card.

〔Effect of the invention〕

As described above, according to the present invention, an IC card is provided with a detection circuit for detecting an input level, and furthermore, a means for permitting or searching communication with an external device based on the input level is provided. Device communication is excellent 91. VC can be performed, which has the effect of significantly improving data reliability.

[Brief explanation of drawings]

FIG. 1 shows a contactless IC card, eg, ?, which is an embodiment of the present invention. The block diagram shown in FIG. S is a circuit diagram of the detection circuit 1G in FIG. 1, FIG. 8 is a circuit diagram of the trigger circuit 87 in FIG. 8, and FIG. 5 is a flowchart showing the operation sequence of the non-contact IC card shown in FIG. K1, and FIG. 6 is a block diagram showing the configuration of the conventional IC card. In the figure, 10 is a detection circuit, 11 is a CPU 16 is an antenna, 17 is a battery, 21 is a coil gg, 24 is a capacitor, 28 is a diode, 25Vi resistor, 26 is a Schmint trigger Lcrill path, 27 is a trigger circuit, 28
is the detection circuit register, 29 is the falling detection circuit% 8
1.85.86 indicates a flip 70 ring, 8s indicates an inverter, and 38d NAND gate. In the figure, (b) - symbols indicate the same or equivalent parts.

Claims (1)

[Claims] An IC card equipped with a data processing means and a storage means that has a built-in battery and communicates with an external device using radio waves as a medium, the IC card having a detection circuit that detects that input radio waves from the external device are at an appropriate level; The output of the detection circuit activates the data processing means of the IC card and also includes means for permitting or prohibiting reception by applying or blocking a bias current to the receiving circuit. A non-contact IC card characterized in that when a detection circuit detects a decrease in the input signal, predetermined error processing is performed.