FR2753428A1 - Protection of vehicle against theft - Google Patents

Abstract

The vehicle key (1) carries a calculating unit (9), memory (10) and infra-red emitter (5). On pressing a switch (4) an authorising code is transmitted (5,11), repeatedly, from memory to the on-board calculator (12). Turning the key to ''Start'' powers up (15,16) the on-board circuits. If correspondence with a code held in on-board memory (13) is not established, e.g. due to signal noise, a time-delayed alarm unit (17) re-submits the signal to the calculator (12). The result of the verification process is passed to a holding circuit (18) to confirm the signal voltage exceeds a specific level. When the authenticity of the signal is established, an output unit (14) permits engine starting. Optionally the communication link is by radio.

Description

Vehicle anti-theft device
The present invention relates to an anti-theft device for a vehicle, which allows an entry engine to start when an electronic code has been verified.

 It is conventionally known to provide a code transmission means and a transmission switch on an engine starting key, and an ignition control unit on the side of the vehicle, which can receive and verify a code signal transmitted by the key. For example, when starting the engine, the key is inserted into a pump lock, a transmission switch is operated at an appropriate temperature, so as to transmit a unique code signal for the key from the signal transmission means of code incorporated in the key, and the validity of the code signal received is determined by a computer provided in the ignition control device of the vehicle, so as to allow the operation of the ignition device only when the correct code signal is received.

 In such an engine starting system, as a provision preventing the execution of a computer error state attributable to electromagnetic noises occurring during engine operation, an alarm sequence controller timing circuit, designed to monitor the state of the computer, can be provided so that the CPU can be reset as soon as the abnormal state, if any, of the output of the warning sequence controller delay circuit resulting from the error computer execution was detected.

However, once the computer is reset, the code signal verification process is also initiated. Consequently, even when the computer is immediately reset to the initial state following an execution error attributable to noises, since the verification process of the code signal is reinitialized and therefore the result of the verification of code is no longer possible at all, the engine stops.

 To avoid these problems attributable to instantaneous noises, it is possible to provide a circuit for preserving the result of code verification placed outside the computer in order to keep the result of code verification for a prescribed period of time, so that the computer, upon resetting to the initial state, can check the state of the preserved result of the verification of the code and, if a successful result of verification of the code has been found and is considered to be retained, allow the ignition control to be reset without being able to repeat the code verification process.

 However, there may be an attempt by an unauthorized person to put the engine control system into operation by skipping the power line on the key switch with intent, and it may also be possible to force the computer of the vehicle equipped with such a code verification device to go into execution error state by using an electromagnetic noise generator and to transmit in a wrong way a successful code verification signal to the conservation circuit of the code verification result. In such a case, even when the computer is reset to the initial state by the warning sequence controller timing circuit, when a computer execution error state is detected, the computer, which has resumed operation after a short period of system downtime due to noise has elapsed, may erroneously conclude that a successful code verification result has been retained, and allow the engine to be started.

 In view of these problems of the prior art, a main object of the present invention is to provide an anti-theft device for a vehicle which allows the vehicle to be put into operation not only when a coincidence of successful crown code has been observed. , but also when the operation of the computer must be resumed immediately after an instantaneous shutdown of the system, while ensuring sufficient protection against any effort made to operate the vehicle illegally.

 A second object of the present invention is to provide an anti-theft device for a vehicle which is secure against an attempted theft, without having the disadvantage of requiring a code coincidence verification process, which takes a long time, when in fact it is not necessary.

 According to the present invention, these objects as well as other objects of the present invention can be achieved by proposing an anti-theft device for a vehicle, designed to allow the operation of a vehicle when a coincidence of electronic code has been observed, comprising: a vehicle control circuit necessary for the operation of said vehicle; code signal transmission means provided on a member separate from said bodywork of said vehicle; code receiving means provided on said vehicle body for receiving said code signal; a computer for verifying the authenticity of said code signal and allowing the operation of said vehicle control circuit when a successful code coincidence has been observed; and means for storing the verification result adapted to keep a successful result of coincidence of code; wherein said computer authorizes operation of said vehicle control unit also when a successful code coincidence result has been stored in said verification result storage means, and said verification result storage means being adapted so that a certain period of time must elapse between a coincidence of success crown code and an effective conservation of said coincidence of code by said means of conservation of the verification result.

 Thus, the fact of providing the means of conservation of the verification result which, for example, may consist of a capacitor, allows the computer to resume operation of the vehicle without having to repeat the code verification process, even when the the computer is reset, for example, by the computer monitoring means, such as a warning sequence controller timing circuit. In addition to the fact that a certain period of time must elapse between a crowned code coincidence and an effective conservation of the code coincidence indication by the means of conservation of the verification result, even if the computer is forced to go into a runtime error, for example by having intentionally produced electromagnetic noises and an accidental code coincidence signal being produced, the means of conservation of the verification result would not immediately retain a code coincidence result successful, so that the computer is prevented from allowing the vehicle control system to be put into operation in a wrong way Typically, the vehicle control circuit consists of an ignition circuit intended for a internal combustion.

 The computer is preferably programmed so as to access the means of conservation of the verification result, before observing a coincidence of code during the start-up and restoration to the initial state. Therefore, the computer performs the code match search process only when a successful code match has not been detected in the means for retaining the verification result, so that the computer or the driver of the vehicle is not bothered by the unnecessary step of finding code coincidence.

 The code signal can be transmitted in a number of possible ways. For example, the code transmission means can include a means for transmitting radiation energy, such as an infrared beam transmission unit which, for example, can be mounted in an ignition key and the reception means code may include means for receiving radiation energy such as an infrared beam receiving unit which, for example, may be provided at a position adjacent to the cylinder of the ignition key lock. Alternatively, the transmission means may include a transponder adapted to generate radiation energy such as a radio wave and the code reception means may include a radiation energy reception unit for receiving radiation energy as well as to activate the transponder.

The present invention will now be described below with reference to the accompanying drawings, in which
Figure 1 is a simplified view of the general structure of an engine starting system to which the present invention is applied;
Figure 2 is a block diagram showing an essential part of the circuit of this system;
Figure 3 is a control flowchart according to the present invention;
FIG. 4 is a flowchart showing the operating mode of the present invention, under normal conditions;
Figure 5 is a flowchart showing the mode of operation of the present invention when an unlawful attempt has been made; and
Figure 6 is a view similar to Figure 2 showing an alternative embodiment of the present invention.

 FIG. 1 is a simplified view of the structure of the key device according to the present invention, which represents an engine starting key 1 mounted in a pump lock 3 provided in a dashboard 2 of the bodywork, for example of a motorcycle.

As shown in FIG. 1, in a handle TA of the key 1 are integrated into a transmission switch 4 used for signal transmission, an infrared beam emission unit 5 used to transmit an infrared signal by commissioning of the transmission switch 4, and an indication light-emitting diode (LED) 6, used to indicate that a signal is being transmitted. The dashboard 2 located on the side of the vehicle body is provided with an infrared beam reception unit 7 intended to receive an infrared beam signal from the infrared beam emission unit 5, when the key 1 is inserted in the pump lock 3 and brought to the ON position of the engine. A Discharge Ignition unit has
Capacitor 8, also called CDI (in English Capacitor
Discharge Ignition), which is connected to the infrared beam receiving unit 7, is fixed to a support, not shown in the drawing, inside the dashboard 2.

Referring to FIG. 2, the key 1 is provided with a computer (p) 9 in order to control the transmission of the code signal and with an identification storage unit (ID) 10 storing a user ID as a code signal. When an ON signal from the transmission switch 4 is received, the computer 9 reads the user ID from the ID storage unit 10 and transmits a corresponding code signal from the unit transmitting infrared beams 5 as an infrared signal and indicates transmission by the
LED 6.

The CDI unit 8 is provided with a computer 12 (p), with a storage unit dID 13 storing the same
User ID as key 1, of a basic circuit unit CDI 14 used to control the ignition of the engine and of a power circuit unit 15 The computer 12 adapts the signal of code user ID on the side of the key 1, which is received by the infrared beam receiving unit 7, at the user ID code signal on the side of the vehicle, which is stored in the storage unit dID 13 and, d after the determination process has been completed, performs a digital ignition command.

 The power source circuit 15 serving to supply electric power to the CDI unit 8 is connected to a LV battery and an alternating current generator (ACG 16), serving as an electric generator operated by a motor not shown on the drawing, in parallel relation. Therefore, when the LV battery is sufficiently charged, the electrical power is supplied by the LV battery. When the LV battery is not sufficiently charged or almost discharged, the ACG 16 produces electrical power for the electrical source.

The computer 12 of the CDI unit 8 is connected to a warning sequence controller timer circuit 17 in order to detect any abnormality of the computer which may be caused by electromagnetic noise, and to reset the
UC 12 when such an anomaly is detected The computer 12 is also connected to a code signal verification result conservation circuit 18 according to the present invention More specifically an RI delay resistor is connected in series with a diode D1 normally connected , to an output terminal OUT of the computer 12 and a capacitor for conserving the verification result C1 is connected between the other end of the resistor R1 and the ground. The node existing between the capacitor C1 and the resistor R1 is connected to an input terminal IN of the computer 12 via a resistor R2 and to a regulated voltage terminal Vcc via a diode D2 with reverse connection. The CDI unit 8 may be provided with a visible light transmitter to indicate that there has been a successful verification of the user ID.

 Based on this retention circuit of the code signal verification result 18, once the code signal has been received and the user ID thus transported has been verified and it has been found to be authentic, a high level signal is produced from the OUT terminal as a successful verification result.

This causes the capacitor C1 to be charged with the conservation of the verification result. The charged voltage is detected from the IN input terminal and if the detected voltage (charged voltage) is equal to or greater than a threshold value, the verification result is considered to be kept.

According to this engine ignition system, when the key 1 is inserted into the pump lock 3 and brought to the ON position of the engine, the code signal is transmitted from the emission unit from the infrared beams 5, and if the LV battery is sufficiently charged, turning the key to the position
ON causes the power circuit 15 to be activated, resulting in the CDI unit receiving electrical power and becoming ready to receive the code signal. When the transmission switch 4 is turned on in this state, the code signal is transmitted a number of times according to a prescribed time interval, and the computer 12 determines whether the code signal is authentic or not. When it is checked that the code signal is authentic, the ignition command is validated via the basic function unit CDI 14, by a normal, authentic manual operation.

 Now, the command made by the computer 12 in this engine starting system will be described below with reference to the flowchart of Figure 3. When the key 1 is mounted in the lock 3, and brought to the position ON the engine, the switching state in service is reached when the CDI unit 8 is supplied and the computer 12 is ready to operate. As soon as the computer becomes operational, a reset step is executed as indicated in step ST1 in FIG. 3.

It is determined in step ST2 whether or not there has already been kept a successful verification result of a code. This is accomplished by the computer 12 accessing the means for preserving the result of code verification or the capacitor C1. In this embodiment, the determining step is carried out by checking that the charged voltage of the capacitor for conserving the result of code verification C1 is not less than the threshold value.

After switching on, if the code signal has not been received, because the capacitor for preserving the code verification result C1 is not charged, the detected voltage is lower than the threshold voltage. Therefore, in step ST2, it is determined that the code signal verification result is not retained and the program proceeds to step ST3. The code signal is received in step ST3, and the code signal is checked in step ST4. It is then determined whether the received code signal coincides with the authentic code signal stored in the storage unit ID 13 or not. If there is a good (perfect) coincidence, the program goes to step
ST5. In step ST5, because the code signal has been verified as authentic, a high level signal is produced from the OUT terminal as a signal indicating that a crown code verification result has been obtained of success.

In step ST6, as indicated by the fifth and sixth graphs of FIG. 4, starting from the top, the capacitor for preserving the verification result Cl begins to be charged by the signal from the verification result of successful code A step ST7, the computer 12 allows the ignition command to the basic function unit CDI 14 and the program goes to step ST8. In step ST8, 1 the computer 12 is the subject of a diagnosis. Any anomalies of the computer 12 include an anomaly in the signal of the timing circuit controller of the alert sequence controller coming from the computer 12 following electromagnetic noises and a system shutdown of the computer 12 following a power fault. If no anomaly is detected, the program returns to step ST7 to resume the ignition command
When an anomaly condition is detected in step ST8, the program returns to step ST1 to reset the computer 12 and to step ST2 to determine the state of the signal verification result code If the engine is normally started and has been running for a duration equal to or greater than a prescribed charging time period Tc, as shown in Figure 4, because the charging voltage of the result storage capacitor C1 verification is equal to the threshold value Vth or higher, a successful code verification result is confirmed and the program goes to stamp ST5 without having to execute the code signal reception process.

 Such a situation can occur for example when the computer 12 is shut down for an extremely short period of time due to noises after the code check has been successfully executed at the time when the engine was the object of the first start, while the result is still kept. In such a case, since the normal code check result has been successfully executed, there is no need to waste time by repeating the code check process. Thus, it is possible to quickly restore the normal being when the computer is shut down for a short period of time.

It is described below, with reference to the flow chart of Figure 5, the operation of the present invention when an attempt is made to produce a successful code verification result by placing the computer 12 in a state of runtime error, using electromagnetic noises by an illicit intention to start the engine *
First, for example, the computer 12 is activated by skipping the power line on the switch. The computer 12 then checks whether the code check has been kept. In this case, the fact that the capacitor for preserving the verification result C1 is not charged and that a successful code verification result has not been preserved, the system is in a state in which it must wait for a code signal.

 In this state, if it is assumed that the electromagnetic noises are generated according to an appropriate timing so as to force the computer 12 to return to an error state. This causes an abnormal signal from the alert sequence controller timing circuit and is detected by the alert sequence controller timing circuit, which resets the computer 12 in response to this. However, during the time that the computer 12 is in a state of execution error, it is possible for the computer 12 to execute a process similar to a verification of successful code, playing luck, and to produce a successful code verification result.

 When a code verification signal is produced as indicated in the fourth graph from the top of FIG. 5, even if there has in fact been no coincidence of a successful code, a high level signal is produced, a high level signal is produced from the terminal OUT of the computer 12, which is shown in FIG. 2, and the capacitor C1 is charged However, according to the present invention, due to the fact that the delay or delay resistor R1 is provided on the line going from the OUT terminal intended to charge the capacitor C1, as mentioned above, the capacitor C1 is not charged instantaneously, but is gradually charged as indicated by the fifth graph starting from the top of FIG. 5 The time constant of the charging circuit is defined by virtue of the existence of the delay resistance R1, so that the charging voltage of the capacitor C1 does not reach the threshold voltage Vth from from the moment when the execution error of the computer 12 was detected by the warning sequence controller timing circuit 17 at the time when the computer 12 is reset.

 Consequently, when the computer 12 has resumed operation after having been reset, the output of the code verification result continues to be in the out-of-service state following the resetting of the computer 12 and the capacitor Ct is in the discharged state When the computer 12 is put back into operation, the state conserved from the result of the code verification is checked. At this time, since the charge voltage of the capacitor C1 is lower than the threshold voltage Vth, and this means that the result of successful code verification is not retained, the signal intended to allow the command ignition is not produced.

 Thus, even if an attempt is made to intentionally cause a runtime error in the computer 12, to obtain a result of code verification successful by accident, by an illicit attempt to start the engine because the charging voltage of the storage capacitor of the code verification result does not reach the threshold voltage Vth, an erroneous judgment of the code verification result can be avoided.

 Figure 6 shows a second embodiment of the present invention. The parts corresponding to those of the previous embodiment are designated by the same reference numbers * The CDI unit 8 comprises a radio transmitter 22 which receives electrical power from the unit from power circuit 15 and is controlled by the computer 12, a radio wave detection circuit 23 having an output end connected to the computer 12 and an antenna coil 21 intended to radiate the radio drone output from the radio transmitter 22 and to receive a radio wave coming from the radio wave detection 23, instead of the infrared beam receiver TT of the first embodiment The key 1 is provided with a transponder 24. The antenna coil 21 is provided on a part of the dashboard which is immediately adjacent of the key housed in the pump lock 3.

 In this embodiment, the computer 12 is put into operation when the key 1 housed in the pump lock 3 is turned to the ON position.

Once the computer 12 begins to operate, the radio power transmitter 22 is actuated by the power circuit unit 15 and radiates radio waves from the antenna coil 21. This radio wave is received by the transponder 24 which in turn transmits a radio wave signal carrying within it a dID code. The radio wave signal coming from the transponder 24 is received by the antenna coil 21 and the dID code is separated by the detection circuit 23. This ID code is compared by the computer 12 with the ID code stored in the storage unit ID 13, and the basic function unit CDI 14 is authorized to operate when a coincidence of successful code has been observed. The operation of this embodiment is also similar to that of the previous embodiment.

Thus, according to the present invention, even when a runtime error has been caused from the computer by accident, because the retained state of the successful code verification result is produced only after a certain period has elapsed time elapsed from the time the verification result was produced, it is possible to prevent the retained state from being produced during the process of resetting the
CPU which follows a computer execution error, so that an illicit attempt to start the engine can be avoided,
Although the present invention has been described in terms of preferred embodiments thereof, it is obvious to those skilled in the art that various changes and modifications are possible without departing from the scope of the present invention.

Claims (7)

 1. Anti-theft device for a vehicle, designed to allow the operation of a vehicle when a coincidence of electronic code has been observed, comprising  a vehicle control circuit (14) necessary for the operation of said vehicle;  code signal transmission means (5) provided on a member separate from said body of said vehicle;  code receiving means (7) provided on said vehicle body for receiving said code signal;  a computer (12) for verifying the authenticity of said code signal and allowing operation of said vehicle control circuit when a successful code match has been observed; and  means for storing the verification result (18) adapted to keep a result of coincidence of successful code;  wherein said computer allows the operation of said vehicle control unit also when a successful code coincidence result has been stored in said verification result storage means (18), and said verification result storage means ( 18) being adapted so that a certain period of time must elapse between a successful coincidence of code and an effective conservation of said coincidence of code by said means for preserving the verification result (18).  2. Anti-theft device for a vehicle according to claim 1, in which the vehicle control circuit comprises an ignition circuit provided for an internal combustion engine.  3. Anti-theft device for a vehicle according to claim 1, further comprising means for monitoring the computers designed to reset said computer when an abnormal condition of said computer is detected.  4. Anti-theft device for a vehicle according to claim 3, in which said computer monitoring means comprise an alert sequence controller timer circuit (17).  5. Anti-theft device for a vehicle according to claim 1, in which said computer is adapted to access said means of conservation of the verification result (18) before establishing the coincidence of code during the putting into service and the restoration to the initial state.  The anti-theft device for a vehicle according to claim 1, wherein said code transmission means comprises a radiation energy transmission unit (5) and said code reception means comprises a radiation energy reception unit (7 ).  The anti-theft device for a vehicle according to claim 1 wherein said code transmission means (5) comprises a transponder adapted to produce radiation energy, and said reception means comprises a radiation energy reception unit (7) designed to receive said radiation energy.