JPH09139985A - Transmitter-receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the rapid improvement of secret talk performance not accomapnied by complication of hardware constitution and a rise of manufactur ing cost, and to flexibly cope with the ciphering method for a transmission signal and the change of the format of cipher code, etc. SOLUTION: In the transmitter-receiver 2 incorporated into the key grip of an ignition key, a microcomputer 3 is switched to its active state by the output of a power source circuit 12 smoothing/rectifying the carrier wave signal from the transmission-reception ECU on the side of an automobile in a state that a resonance circuit part 7 receives the carrier wave signal. A detection circuit 13 discriminates the question signal imparted with the carrier wave signal through the resonance circuit part 7 and imparts the signal to the microcomputer 3. When the microcomputer 3 switched to the active state receives the question signal, the microcomputer 3 perform the control of returning the response signal of a ciphered state to the side of a transmission-reception ECU by preparing the cipher code by the function calculation based on the discrimination code, the code for calculation and the function expression in an EEPROM 4 and performing the on/off control of the FET 6a within a modulation circuit 6 by the mode corresponding to the cipher code.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transceiver having a transponder function of returning a response signal when a power signal and an inquiry signal are given.

[0002]

2. Description of the Related Art For example, in an automobile, a function as an electronic key using an electric identification code is added to an ignition key in order to improve security performance against theft. . In this case, it is general that a transmitter / receiver is built in the key grip of the ignition key, and the transmitter / receiver has an identification code stored in advance when a power signal and an inquiry signal are given from the outside. It has a transponder function of returning a response signal including a.

In this case, because of the electronic key function, the electric power signal and the inquiry signal are transmitted to the automobile side in a state where the ignition key configured as described above is inserted into the key hole for starting the engine. Then, the response signal is received from the transmission / reception device on the side of the ignition key, and the immobilizer function of permitting the engine start by the ignition key only when the identification code in the response signal matches the preset identification code is provided. A transmission / reception ECU provided is provided.

[0004]

The transponder function of the conventional transmitter / receiver is generally composed of hard logic. For this reason, the identification code is usually fixed, and there is a circumstance in which its duplication becomes relatively easy. As a result, the confidentiality performance and thus the security performance against theft cannot be sufficiently improved. There was a point.

In order to deal with such a problem, it is effective to encrypt the identification code or the like. However, in the conventional transmission / reception apparatus, even if such a means is adopted, complicated encryption is required. Since it is difficult, it is not possible to expect a dramatic improvement in the confidential communication performance, and a new problem arises in that the hardware configuration becomes complicated and the cost increases. Moreover, in the transmitter / receiver described above, it is difficult to change the hardware configuration once the key grip is built into the key grip.
Since the encryption method and its code format cannot be changed, and the encryption processing method is uniquely determined, when different encryption is performed for each automobile manufacturer or destination, each transmission / reception There is also a problem that the manufacturing workability deteriorates because it is necessary to prepare a different hardware configuration for each device.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to realize a dramatic improvement in confidential communication performance without complicating the hardware configuration and increasing the manufacturing cost and transmitting the data. It is an object of the present invention to provide a transmission / reception device capable of flexibly coping with a change in a signal encryption method and a format of its encryption code.

[0007]

In order to achieve the above object, a transmitting / receiving apparatus according to the present invention includes an identification code stored in advance in response to an inquiry signal when receiving a power signal and an inquiry signal from the outside. In a transmission / reception device having a transponder function for returning a response signal, a resonance circuit section composed of a transponder coil and a resonance capacitor, and the resonance circuit section being electromagnetically coupled to an external antenna coil, the resonance coil is used to resonate with the resonance circuit section. A power supply circuit for rectifying and smoothing a power signal given through a circuit section, a microcomputer operated by an output of the power supply circuit, and a resonance circuit set to a time constant smaller than a time constant of a smoothing function part by the power supply circuit. Part is electromagnetically coupled to an external antenna coil, Detection circuit for discriminating an interrogation signal given together with the power signal to give to the microcomputer, storage means for storing a unique identification code, and transmitting the response signal by changing the impedance of the resonance circuit section. And a modulation circuit for performing an operation, and when the microcomputer receives an inquiry signal through the detection circuit, creates an encryption code by performing an operation using the identification code read from the storage means. By controlling the modulation circuit to operate in a mode corresponding to the encryption code, transmission control of a response signal through the resonance circuit section is performed.

According to this structure, since the response signal to the inquiry signal is transmitted in the encrypted state, the confidential communication performance is improved. In this case, since the response signal is encrypted based on the calculation by the microcomputer, any encryption can be performed without complicating the hardware configuration. Performance can be dramatically improved. Further, since the encryption method and the like can be easily changed only by changing the storage contents on the microcomputer side, various encryption processing methods can be set, and different hardware can be used for each transmission / reception device. It is not necessary to prepare a wear structure, and as a result, it is possible to improve the manufacturing workability and reduce the cost (claim 1).

In this case, the identification code may be changeable by using a data rewritable nonvolatile memory as the storage means.
With this configuration, it is possible to easily set and change the format of the identification code, improve the confidentiality performance and the degree of freedom in design, and use the storage means for storing other useful data. This makes it convenient for practical use (claim 2).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to an automobile load control system will be described below with reference to the drawings. FIG. 1 shows a key grip of an automobile ignition key (shown by reference numeral 1 in FIG. 2).
The electrical configuration of the built-in transceiver 2 in the unitized state is shown.

The transmitter / receiver 2 is mainly composed of a microcomputer 3 and includes a preset identification code ΔB in response to the inquiry signal when receiving a power signal and an inquiry signal from the outside. A transponder function for returning a response signal is set, and its specific configuration will be described below.

That is, the microcomputer 3 internally has an EEPROM 4 (corresponding to a storage means and a non-volatile memory in the present invention), a resistor 5a for a power-on reset circuit 5 described later, and an n-channel FET 6a for a modulation circuit 6 described later.
In particular, the above EEPROM
Reference numeral 4 stores an identification code ΔB and a calculation code ΔC unique to the corresponding ignition key 1, and also stores a functional expression f as described later for generating the encryption code.

The resonance circuit section 7 is constituted by connecting a transponder coil 8 and a resonance capacitor 9 in parallel between the signal line SL and the ground terminal, and the resonance frequency of the resonance circuit section 7 is set on the automobile side. It is set to be equal to the frequency band of the carrier signal (corresponding to the power signal in the present invention) transmitted from the ECU (denoted by reference numeral 10 in FIG. 2).

The power supply circuit 12 connected to the signal line SL via the resistor 11 is for supplying an output obtained by rectifying and smoothing the carrier wave signal received by the resonance circuit section 7 to the power supply terminal VDD of the microcomputer 3. Rectifying diode 12a, smoothing capacitor 12b, constant voltage diode 1
2c and the resistor 12d are connected as shown in the figure.

The detection circuit 13 connected to the signal line SL via the resistor 11 discriminates an inquiry signal given together with the carrier signal through the resonance circuit section 7 and gives it to the input port PI of the microcomputer 3. , A detection diode 13a, a capacitor 13b, and resistors 13c and 13d are connected as shown in the figure.

In this case, the time constant of the detection circuit 13 is
It is set to a value sufficiently smaller than the charging time constant of the smoothing function portion by the power supply circuit 12, whereby the inquiry signal can be discriminated.

The modulation circuit 6 including the FET 6a has a configuration in which a series circuit between the modulation capacitor 6b and the source / drain of the FET 6a is connected in parallel with the resonance capacitor 9 of the resonance circuit section 7. , Its FET6
The impedance of the resonance circuit portion 7 can be changed according to the on / off state of a.

The reset circuit 5 puts the microcomputer 3 in a reset state until the voltage level applied to the power supply terminal VDD of the microcomputer 3 (the output voltage level of the power supply circuit 12) rises above a predetermined level. This is for the power-on reset function of holding, and has a configuration in which the diode 5b, the capacitor 5c and the resistor 5a are connected as shown in the figure. Also,
Oscillation circuit 14 including resistor 14a and capacitor 14b
Are provided to determine the clock frequency of the microcomputer 3.

Therefore, in the following, the function of the transmitting / receiving apparatus 2 configured as described above will be described together with the control content of the microcomputer 3. That is, when the inquiry signal including a carrier signal (power signal) and a predetermined random number code ΔA, which will be described later, transmitted from the transmission / reception ECU 10 side is received through the resonance circuit section 7, the power supply circuit 1
2, when the received carrier wave signal is rectified / smoothed and applied to the power supply terminal VDD of the microcomputer 3, and its output voltage rises above a predetermined level,
When the reset hold state by the reset circuit 5 is released,
The microcomputer 3 is switched to the active state. Further, the detection circuit 13 discriminates the received inquiry signal and supplies it to the input port PI of the microcomputer 3.

The microcomputer 3 in the active state as described above operates the modulation circuit 6 in response to the interrogation signal being given through the detection circuit 13,
The transponder has a function of transmitting (returning) the encrypted response signal including the identification code ΔB stored in the EEPROM 4 through the resonance circuit section 7.

In this case, the microcomputer 3 is configured to encrypt the response signal as follows, for example. That is, when the inquiry signal is received, the EEP
The identification code ΔB, the calculation code ΔC, and the functional expression f are read from the ROM 4, and the random number code ΔA in the interrogation signal and the identification code ΔB are read based on the functional expression f.
And a calculation code ΔC are used as variables, that is, a calculation of f (ΔA, ΔB, ΔC) is performed, and the calculation result is obtained as an encryption code ΔD.

In the microcomputer 3, the FET 6a in the modulation circuit 6 is on / off controlled in a mode according to the code code ΔD to change the impedance of the resonance circuit portion 7 to receive the carrier wave. The signal is amplitude-modulated in a mode according to the encryption code ΔD, and the impedance change state of the resonance circuit portion 7 by the modulation circuit 6 is transmitted / received by the transmission / reception ECU 1
By detecting on the 0 side, the encrypted response signal is returned to the transmitting / receiving ECU 10 side.

On the other hand, FIG. 2 schematically shows the configuration of the entire system by combining functional blocks.
In FIG. 2, an antenna coil 16 is provided around an ignition key cylinder 15 for an automobile, and when the ignition key 1 is inserted into the key cylinder 15, the antenna coil 1 is
6 and the transponder coil 8 (see FIG. 1) incorporated in the ignition key 1 are electromagnetically coupled.

The transmission / reception ECU 1 provided on the automobile side
Reference numeral 0 indicates a microcomputer 17 as a main component, and the microcomputer 17 is turned on by an IG switch 18 and a key remind switch 19 having a well-known structure provided corresponding to the ignition key cylinder 15. Signals are input via the switch interface 20. In this case, for the microcomputer 17, the antenna coil 16
The received signal is input via the receiving circuit 21.

The microcomputer 17 is so constructed as to control the transmission through the antenna coil 16 by the output of the power amplifier 22. The specific control contents will be described later. In addition, the microcomputer 17 is configured to send and receive signals to and from the engine control ECU 23 through the serial interface 24, and as described later, an immobilizer function capable of selectively prohibiting an engine starting operation by the engine control ECU 23. Is set.

Further, the microcomputer 17 has an E
Data is transmitted and received to and from the EPROM 25. The EEPROM 25 includes an EEPROM 4 on the side of the ignition key 1 prepared for the vehicle.
The identification code ΔB, the operation code ΔC, and the operation code ΔB that are the same as the function code f stored in
C and the functional expression f are stored in advance.

Now, in the following, the transmission / reception ECU 10
The control contents of the microcomputer 17 included in will be described together with the operation of related parts. That is, when the microcomputer 17 receives an ON signal from the key reminding switch 19 and the IG switch 18, that is, when the ignition key 1 is inserted into the ignition key cylinder 15 and operated to the ON position (in this state, The antenna coil 16 and the transponder coil 8 on the side of the ignition key 1 are electromagnetically coupled), for example, a new random number code ΔA is generated by a predetermined function operation, and the random number code ΔA is stored in an internal memory (not shown). While storing, while generating a pulse train interrogation signal including the random number code ΔA and operating the power amplifier 22, the antenna coil 16 is operated.
Then, the interrogation signal including the carrier wave signal of the predetermined frequency and the random number code ΔA superimposed on the carrier wave signal is transmitted.

As a result, the antenna coil 16 is connected to the transmitter / receiver 2 (see FIG. 1) on the ignition key 1 side.
The carrier wave signal and the interrogation signal are transmitted via the carrier wave signal. In the transmitter / receiver 2, the CPU 3 is switched to the active state by the carrier wave signal as described above. Random code ΔA, the identification code ΔB stored in the EEPROM 4, the operation code ΔC, and the cryptographic code ΔD by the functional operation using the functional expression f, and the response signal encrypted by the cryptographic code ΔD is returned. The transponder function comes to be exhibited.

The microcomputer 17 uses the random number codes ΔA and EEPRO read from an internal memory (not shown).
Identification code ΔB read from M25, calculation code Δ
The cryptographic code ΔD is obtained by calculating f (ΔA, ΔB, ΔC) based on C and the functional expression f, and the cryptographic code ΔD and the cryptographic code included in the response signal returned from the transmitter / receiver 2 side. The decoding operation of comparing with the code ΔD is performed, and when the two do not match, the engine control ECU 23 prohibits the starting of the automobile engine.

Therefore, when the IG switch 18 is turned on by the improper ignition key 1 whose identification code does not match, the automobile engine is not started, and the security against theft is improved. .

On the other hand, when the code code ΔD obtained by the calculation and the code code ΔD included in the returned response signal match by the decoding operation, the engine control E
The starting of the automobile engine by the CU 23 is permitted.

Therefore, in the state where the proper ignition key 1 with which the encryption code ΔD generated based on the identification code ΔB and the like matches is inserted into the ignition key cylinder 15, the starting of the vehicle engine through the engine control ECU 23 is permitted. The immobilizer function is exhibited as described above.

In short, according to the configuration of this embodiment described above, the following effects can be obtained. Since the transmission / reception device 2 has a configuration in which the response signal to the inquiry signal transmitted from the transmission / reception ECU 10 is returned in an encrypted state, the confidential communication performance, and thus the security performance against theft of the car, is improved. . In this case, since the encryption of the response signal is performed based on the function calculation in the microcomputer 3, the hardware configuration becomes complicated and the cost increases accordingly as in the conventional configuration. In addition to the possibility of inviting it, complicated encryption can be arbitrarily performed, and the confidential communication performance can be dramatically improved.

Further, since the encryption method and the like can be easily changed only by changing the software of the microcomputer 3 or the stored contents, the encryption processing method can be set in various ways. It is not necessary to prepare a different hardware configuration for each transmitter / receiver 2, and as a result, manufacturing workability can be improved and cost can be reduced. Moreover, since the control of the transponder function can be performed by the program of the microcomputer 3, the communication protocol between the transmission / reception device 2 and the transmission / reception ECU 10 is not fixed to one, and the degree of freedom in design is increased. Get higher

Further, since the identification code ΔB, the operation code ΔC and the function formula f necessary for encrypting the response signal are stored in the EEPROM 4 in which the data can be rewritten, the format setting of the identification code ΔB and The encryption method including the change and the change of the function expression f can be easily changed, and the confidentiality performance and the degree of freedom in design can be significantly improved, and the EEPROM 4 can be used for storing other useful data. Being able to do this will be convenient in actual use.

The present invention is not limited to the above-mentioned embodiments, but can be expanded or modified as described below. Although the engine control ECU 23 is given as an example of the control target, other loads may be controlled. At least one of the identification code ΔB and the functional expression f may be stored in the EEPROM 4, and one of the identification code ΔB and the functional expression may be fixed. Further, it goes without saying that the encryption method of the response signal is not limited to the above embodiment.

[0037]

As is apparent from the above description, according to the transmitting / receiving apparatus of the present invention, the response signal for the transponder function is encrypted based on the function calculation in the microcomputer. Therefore, it is possible to accelerate the dramatic improvement of confidential communication performance only by changing the software, and it is possible to suppress the rise in manufacturing cost, as well as the encryption method of the transmission signal and the format of the encryption code. This has the beneficial effect of being able to flexibly respond to changes in.

[Brief description of the drawings]

FIG. 1 is an electrical configuration diagram of a transmitter / receiver showing an embodiment of the present invention.

FIG. 2 is a functional block diagram showing the configuration of the entire system.

[Explanation of symbols]

In the drawing, 1 is an ignition key, 2 is a transmitter / receiver, and 3
Is a microcomputer, 4 is an EEPROM (storage means, non-volatile memory), 6 is a modulation circuit, 7 is a resonance circuit section, 8 is a transponder coil, 9 is a resonance capacitor, 10 is a transmission / reception ECU, 12 is a power supply circuit, and 13 is A detection circuit, 15 is an ignition key cylinder, 16 is an antenna coil, and 23 is an engine control ECU.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sadao Kokubun No. 1 Noda, Toyoda, Oguchi-machi, Niwa-gun, Aichi Prefecture Tokai Rika Electric Co., Ltd.

Claims (2)

[Claims] 1. A transmitter / receiver having a transponder function for returning a response signal including an identification code stored in advance in response to an inquiry signal when receiving a power signal and an inquiry signal from the outside, wherein a transponder coil and a resonance are provided. A resonance circuit section composed of a capacitor; a power supply circuit for rectifying and smoothing a power signal applied from the antenna coil through the resonance circuit section in a state where the resonance circuit section is electromagnetically coupled to an external antenna coil; And a microcomputer operated by the output of the power supply circuit, the time constant being set to a time constant smaller than the time constant of the smoothing function part, and the resonance circuit part being electromagnetically coupled to an external antenna coil, The interrogation signal provided together with the power signal is discriminated through the resonance circuit part to discriminate the my (B) a detection circuit to be given to the computer, storage means for storing a unique identification code, and a modulation circuit for performing the operation of transmitting the response signal by changing the impedance of the resonance circuit section, wherein the microcomputer is When an inquiry signal is received through the detection circuit, an encryption code is created by performing an operation using the identification code read from the storage means, and the modulation circuit is operated in a mode according to the encryption code. The transmitting / receiving device is configured to control transmission of a response signal through the resonance circuit section. 2. The storage means is configured to change the identification code by using a non-volatile memory in which data can be rewritten.
The transmitting / receiving device according to any one of the preceding claims.