JP3332748B2 - Key device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a key device having an immobilizer function.

[0002]

2. Description of the Related Art In recent years, due to security requirements, in vehicles such as automobiles, an immobilizer system has been proposed which permits mechanical starting of an ignition key and permits starting of an engine only when electronic identity is confirmed. It has been developed and is widespread in countries and regions where car theft cases occur frequently. In such an immobilizer system, generally, a transponder is embedded in an ignition key for starting an engine by switching an ignition switch of an automobile, modulating a predetermined secret code from the transponder, transmitting and outputting, and transmitting and outputting from the transponder. The PIN code signal is received by the key device installed on the vehicle side to determine the identity of the PIN code, and only when the PIN code is confirmed, the key device outputs a start permission signal to the engine start circuit. The structure is as follows. Thus, the engine can be started only when the shape of the key groove of the used ignition key matches and the identity of the personal identification code is confirmed.

Here, the operation of the immobilizer system for confirming the electronic identity of the ignition key will be described in detail. When the ignition key is inserted into the key hole of the cylinder lock for ignition and the ignition switch is switched to, for example, an ON position, the transmission / reception coil on the key device side is driven at a high frequency for a predetermined time by a high frequency circuit including a modulation / demodulation circuit provided in the key device on the vehicle side. You. Then, the transponder-side transmission / reception coil embedded in the ignition key is magnetically coupled to the key device-side transmission / reception coil, and a current flows to the transponder side by an electromagnetic induction action, and a charge is stored in a capacitor provided in the transponder. The transponder modulates the password by using the charge stored in the
The wave is transmitted and output from its own transmitting / receiving coil as a carrier wave. As a result, the two transmission / reception coils are magnetically coupled again, and the password code signal is transmitted to the high frequency circuit via the transmission / reception coil on the key device side. In the key device, the received security code signal is demodulated by a high frequency circuit, and the security code is decoded by the control circuit. As a result, the control circuit outputs a start permission signal to the engine ECU only when the identity of the personal identification code is determined. This confirms the electronic identity of the ignition key.

[0004]

When the immobilizer system is mounted on an actual automobile, the transmission / reception coil on the key device side is arranged around the ignition cylinder lock installed on the steering column. The circuit portion of the key device including the control circuit is installed in a dead space in a vehicle, for example, under a seat, behind a dashboard, in an engine room, a trunk room, or the like.
That is, since the circuit section of the key device needs to be installed in a place that is invisible to human eyes, the installation place is limited to a specific place. For this reason, in the key device, it is often necessary to arrange the transmitting / receiving coil and the circuit unit at a remote place. However, if the distance from the transmitting / receiving coil to the circuit unit is long, there is a problem that an external electromagnetic field affects signal transmission between the transmitting and receiving coils and a malfunction easily occurs.

Further, in the key device, since the transmitting / receiving coil and the circuit portion are formed separately, there is a problem that various operations and handling are complicated. For example, when the immobilizer system is installed in an automobile, the transmitting and receiving coils are mounted at predetermined locations with the transmitting and receiving coils, the circuit section is mounted at a predetermined location with the circuit section, and furthermore, the transmission lines connecting these are not exposed to human eyes. The work is extremely troublesome. Also, when packing the immobilizer system as a product, the transmitting / receiving coil and the circuit unit are separate, and these are connected by a transmission line, so that the operation is complicated and troublesome.

An object of the present invention is to provide a key device capable of accurately transmitting a signal received by a transmission / reception coil to a circuit section.

Another object of the present invention is to provide a key device capable of facilitating various operations and handling.

[0008]

According to a first aspect of the present invention, there is provided a key device comprising: a transmission / reception coil; a high-frequency drive of the transmission / reception coil to generate a magnetic field; and a demodulation of a signal received from a transponder via the transmission / reception coil. A high-frequency circuit that outputs a security code, a memory that stores the security code, and whether the security code signal received from the high-frequency circuit is appropriate or not based on the security code stored in the memory, and starts the engine according to the determination result. A control circuit that outputs a permission signal, and a coil holding unit that is arranged near a key insertion port of the ignition cylinder lock and holds a transmission / reception coil.
A casing that is integrated with the coil holding portion and houses and holds a high-frequency circuit, a memory, and a control circuit;
The first substrate to be mounted, and the memory and control circuit are mounted
A second substrate, and a first substrate and a second substrate in a casing.
The two substrates are stacked and stored and held.

Such a key device of the present invention constitutes an immobilizer system together with an ignition key having a built-in transponder. That is, when a magnetic field is generated in the transmission / reception coil by high-frequency driving by the high-frequency circuit, power is supplied to the transponder by an electromagnetic induction effect due to magnetic coupling with the transmission / reception coil. Then, when the transponder after power supply transmits and outputs the modulated personal identification code signal, the personal identification code signal transmitted and output from the transponder side is received via the transmitting and receiving coil by the electromagnetic induction effect due to the magnetic coupling. The received password code signal is demodulated by the high-frequency circuit and collated with the password stored in the memory by the control circuit. As a result, when the identity of the personal identification code is confirmed, the control circuit outputs an engine start permission signal. At this time, since the coil holding portion for holding the transmitting and receiving coil and the casing for housing and holding the high-frequency circuit and the control circuit are integrated, the distance between the transmitting and receiving coil, the high-frequency circuit and the control circuit is shortened, and The external electromagnetic field hardly affects the signal transmission. Therefore,
The signal received by the transmitting / receiving coil is accurately transmitted to the high frequency circuit and the control circuit. Further, since the transmitting and receiving coil, the high-frequency circuit, and the control circuit are integrated, various operations and handling are easy. Also, a high frequency circuit that emits high frequency
Path is mounted on a separate board from the control circuit and memory.
Control circuit from the effects of harmful electromagnetic waves generated by high-frequency circuits.
The road is protected and operation is stable. In addition, the substrate becomes two
Due to the division, the casing becomes smaller.

[0010]

[0011]

An embodiment of the present invention will be described with reference to the drawings. The immobilizer system for a vehicle shown in the present embodiment includes a key device 2 attached around an ignition switch 1 and a key unit 4 including a transponder 3 described later. Hereinafter, each will be described in detail.

FIG. 1 is a perspective view showing an external structure of an immobilizer system together with an ignition switch 1.

The ignition switch 1 is basically constituted by a cylinder lock 5 having four contacts for ignition. As shown in FIG. 1, the four contacts are of four types commonly used: OFF, ACC, ON, and ST. The OFF position is the only position that does not supply power to each part and allows the later-described ignition key 7 of the key unit 4 provided to the key insertion opening 6 of the cylinder lock 5 to be attached and detached. The ACC position is a position that allows power supply to accessories such as a radio and a power window. The ON position is a position in which power supply to all electric and electronic components including the control block (ECU) of the engine is permitted. The ST position is a position for driving the starter of the engine to start the engine, and the ignition key 7 located at the ST position is returned to the ON position by the force of a return spring (not shown).

FIG. 2 is a perspective view of the key device 2, FIG. 3 is an exploded perspective view thereof, and FIG. 4 is a simplified block diagram showing a circuit configuration of the immobilizer system.

The key device 2 includes a transmission / reception coil 8, and as a circuit section 9, an RF circuit 10 (R) as a high-frequency circuit.
F: Radio Frequency) and, E ² PROM11 (E ² PROM as a memory for storing a personal identification code: Electric
ally Erasable Programmable Read Only Memory). The RF circuit 10 has a function of driving the transmitting and receiving coil 8 at a high frequency by being supplied with power from a battery (not shown) on the vehicle side, and a control circuit for controlling a personal identification code obtained by demodulating a personal identification code signal received from the transponder 3 via the transmission and reception coil 8. 12 is a high-frequency circuit having a function of outputting to the high-frequency circuit 12. The control circuit 12 includes a CP (not shown).
A microcomputer including a U and a memory is provided. The control circuit 12 is connected to the ECU of the engine via the connector 15 attached to the first board 16, calls up the security code from the E ² PROM 11, and demodulates the called security code and the RF circuit 10. When the two passwords are compared with each other and the two passwords match, a start permission signal is output to the ECU of the engine.

Here, the transmission / reception coil 8 is wound and held by a ring-shaped coil holding portion 13 which is attached near the periphery of the cylinder lock 5 constituting the ignition switch 1. The RF circuit 10, the E ² PROM 11, and the control circuit 12 are housed and held in a casing 14 that is formed integrally with the coil holding unit 13. Here, the RF circuit 10 includes a battery (not shown) of the vehicle and an ECU of the engine.
The E ² PROM 11 and the control circuit 12 are mounted on a second substrate 17 together with a connector 15 connected to the second substrate 17. These two substrates 16, 17
Are stacked in a two-layer structure, and are integrally housed and held in the casing 14. The casing 14 includes a casing body 14a and a cover 14b that is clicked and stopped on the casing body 14a.
The boards 16 and 17 are housed in the casing 14 and the cover 14b is closed, so that the boards 16 and 17 are fixedly housed in the casing 14.

Next, the key unit 4 will be described.
The key unit 4 has an external configuration as an ignition key 7, and the transponder 3 is built in a grip portion 18. The transponder 3 has a built-in transmitting / receiving coil (not shown) magnetically coupled to the transmitting / receiving coil 8 on the side of the key device 2 driven at a high frequency, and stores electric power generated by electromagnetic induction by such magnetic coupling as a charge in a capacitor (not shown). In this structure, a password stored in this capacitor is modulated as an electromotive force to modulate a personal identification code, and an FM wave is transmitted as a carrier wave from a built-in transmitting / receiving coil.

The operation will be described.

First, in order to start the engine of the automobile, the ignition key 7 of the key unit 4 is inserted into the key slot 6 of the cylinder lock 5 of the ignition switch 1.
When the position of the cylinder lock 5 is turned to the ON position, the RF circuit 10 is activated for a predetermined time and the transmission / reception coil 8 is driven at a high frequency. As a result, a magnetic field is generated around the transmission / reception coil 8, and the transmission / reception coil 8 and the transmission / reception coil built in the transponder 3 are magnetically coupled. Then, the transmission / reception coil built in the transponder 3 receives the electromagnetic induction action, and the electric charge is stored in the capacitor of the transponder 3. Here, the predetermined time during which the RF circuit 10 is activated is a time during which sufficient charge is stored in the capacitor of the transponder 3. Therefore, the power supply to the transponder 3 is stopped after the electric charge is sufficiently stored in the capacitor of the transponder 3, thereby slightly lowering the potential of the capacitor.
The transponder 3 detects such a drop in the potential of the capacitor, and uses this as a trigger to modulate the personal identification code signal and to transmit and output the personal identification code signal modulated using the FM wave as a carrier wave. Thus, the transmission / reception coil incorporated in the transponder 3 and the transmission / reception coil 8 on the key device 2 side are magnetically coupled, and the RF circuit 10 of the key device 2 receives the password code signal. Therefore, the RF circuit 10 demodulates the received security code signal and sends it to the control circuit 12. The control circuit 12 decodes the security code signal to obtain a security code, and the E ² PROM 11
Check with the PIN code stored in. As a result of matching,
When it is determined that the two passwords match, the control circuit 12 outputs a start permission signal to the ECU of the engine. Thereby, the start of the engine is permitted.

During the operation of the immobilizer, the coil holding portion 13 for winding and holding the transmitting and receiving coil 8 and the casing 14 for housing and holding the control circuit 12 are integrated, so that the transmitting and receiving coil 8 and the circuit portion 9 are integrated. , And the external electromagnetic field is less likely to affect signal transmission therebetween. Therefore, the signal received by the transmitting / receiving coil 8 is accurately transmitted to the RF circuit 10 and the control circuit 12,
False detection is prevented.

The operating RF circuit 10 generates a high frequency. Since the RF circuit 10 and the control circuit 12 are mounted on separate substrates 16 and 17, the RF circuit 10
The control circuit 12 is protected from the influence of harmful electromagnetic waves generated by the device and the operation is stabilized. Moreover, since the substrates 16 and 17 are divided into two, the casing 14 is also reduced in size.

Further, since the transmission / reception coil 8 and the circuit section 9 are integrated in the key device 2 , various operations and handling, for example, manufacturing and assembling operations, packing operations during distribution, installation operations to automobiles, and the like are performed. Easy.

Here, the control circuit 1 of the key device 2 in FIG.
The switch 19 connected to the switch 2 is a switch for switching the operation mode of the key device 2. That is,
When the switch 19 is in the open state, the mode is the collation mode for performing the above-described security code collating operation, whereas when the switch 19 is in the closed state, the mode is the registration mode. In the registration mode, the signal is transmitted and output from the transponder 3 and the RF circuit 1
The code obtained by demodulation at 0 is the E ² PROM 11
Is stored in Thereby, even if the key unit 4 is lost, for example, the new key unit 4
Thus, the personal identification code can be easily registered on the key device 2 side.

In the present embodiment, the mode in which the RF circuit 10 drives the transmission / reception coil 8 at high frequency when the cylinder lock 5 is turned to the ON position has been described. It is detected that the key is inserted into the key insertion slot 6 or the cylinder lock 5 is detected.
May be configured to detect that the transmission / reception coil 8 has been moved to another position such as ACC, and drive the transmission / reception coil 8 at a high frequency.

[0025]

According to the first aspect of the present invention, there is provided an ignition key including a transponder together with an ignition key, and a component of a key device constituting an immobilizer system, wherein a coil holding portion disposed near a key insertion opening of an ignition cylinder lock. Since the transmitting and receiving coil is held and the high-frequency circuit, the memory and the control circuit are stored and held in the casing, and the casing and the coil holding unit are integrated, the distance between the transmitting and receiving coil, the high-frequency circuit and the control circuit can be shortened. The influence of the external electromagnetic field on signal transmission during that time can be removed, and malfunction can be prevented. Further, since the entire key device is integrally formed by integrating the casing and the coil holding portion, various operations and handling can be facilitated. In addition, a high-frequency circuit is mounted on the first substrate
And the memory and the control circuit are mounted on the second substrate.
So that two substrates are stacked and stored in the casing
The control circuit and the memory emit a high frequency.
Isolated from the circuit, which can
It can protect the control circuit from the effects of harmful electromagnetic waves,
Operation can be stabilized. In addition, two substrates
Since the casing is divided, the casing can be reduced in size.

[0026]

[Brief description of the drawings]

FIG. 1 is a perspective view showing an external configuration of an immobilizer system together with an ignition switch as one embodiment of the present invention.

FIG. 2 is a perspective view of a key device.

FIG. 3 is an exploded perspective view of the key device.

FIG. 4 is a block diagram showing a simplified circuit configuration of the immobilizer system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 3 transponder 5 ignition cylinder lock 6 key insertion port 8 transmission / reception coil 10 high-frequency circuit 11 memory 12 control circuit 13 coil holding unit 14 casing 16 first substrate 17 second substrate

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-8-53048 (JP, A) JP-A-10-1079 (JP, A) JP-A-6-13918 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B60R 25/04 E05B 1/00-75/00

Claims (1)

(57) [Claims] 1. A transmitting / receiving coil, a high-frequency circuit for driving the transmitting / receiving coil at a high frequency to generate a magnetic field, demodulating a signal received from a transponder via the transmitting / receiving coil, and outputting a password, and storing the password. A control circuit that determines whether the password code signal received from the high-frequency circuit is appropriate based on the password stored in the memory, and outputs an engine start permission signal in accordance with the determination result; and an ignition cylinder. is disposed near the key hole of the lock, and the coil holding portion for holding the transmitting and receiving coil is integrated with the coil holding portion, a casing for housing holding the said high frequency circuit and the memory and the control circuit, wherein comprises a first substrate for mounting a high-frequency circuit, a second substrate for mounting the memory and the control circuit, the Wherein said first substrate in said casing second
A key device for storing and holding a plurality of substrates .