IE80962B1

IE80962B1 - Arming apparatus for a security circuit

Info

Publication number: IE80962B1
Application number: IE940218A
Authority: IE
Inventors: Joseph Oliver Mcbreen; William Francis Clancy; Howard James Morris; Ronan Vincent Kelly; Aidan Heeran
Original assignee: Hi Key Ltd
Priority date: 1994-03-11
Filing date: 1994-03-11
Publication date: 1999-07-14
Also published as: GB2287563B; IE940218A1; GB2287563A; GB9502831D0

Abstract

An arming circuit (1) arms and disarms a car immobiliser (2) on reception of a security code which matches a stored reference security code. The arming circuit (1) is operable in an input mode for enabling inputting and storing of new reference security codes. The reference security codes are stored as reference master security codes and reference secondary security codes. A reference security code may only be inputted after a master security code has been received.

Description

Arming apparatus for a security circuit The present invention relates to arming apparatus for arming and disarming a security circuit, and in particular though not limited to arming apparatus for arming and disarming a vehicle immobiliser, a vehicle alarm, or a combination vehicle immobiliser and alarm.

Vehicle immobilisers and alarms, in particular, car immobilisers and alarms are extensively used because of the high instance of car theft. Arming and disarming of such immobilisers and alarms, may be carried out by a mechanical key operated switch or by the receipt of a security code, which in general, comprises a string of digitised digits. In the latter case, an arming circuit, which comprises suitable control circuitry, generally, operates under the control of software, and reads the received security code, compares the security code with a stored reference security code, and on the two codes matching a signal is outputted for changing r the state of the immobiliser. For example, if the immobiliser is in the armed mode, the outputted signal disarms the immobiliser, and vice versa. The security code for arming and disarming the immobiliser may be received by the arming circuit by either a radio circuit which receives the security code having been transmitted from a remote transmitter. Alternatively, the security code may be delivered to the arming circuit by an electronic key within which the security code is stored and transferred through electrical contacts into the arming circuit. Such electronic keys are known, and a typical electronic key is that supplied by Dallas Semi Conductors of the United States of America under the Trade Mark DALLAS P/W Parts Nos.

DS 1990A-F3 and DS1233A-10T/R.

In general, it is desirable that a number of keys or 10 remote transmitters be provided for operating the same immobiliser. For example, if a number of people are to drive the car, it is convenient that each individual has a key or remote transmitter as the case may be. Indeed, where only one driver is involved, it is desirable that at least one spare key or remote transmitter should be provided.

Where the arming and disarming of an immobiliser is carried out by a key operating a mechanical switch, it r is relatively easy to provide a number of duplicate 20 keys.

However, in the case of electronic keys and remote transmitters, providing a duplicate electronic key or a duplicate remote transmitter is not quite so simple.

In general, for security reasons each electronic key which is produced, and indeed each remote transmitter stores only one security code, and this security code is randomly selected during production of the electronic key or remote transmitter. Thus, the possibility of being able to obtain two electronic keys or two remote transmitters with identical security codes is difficult if not impossible. To overcome this problem, in general, manufacturers of immobiliser make provisions for enabling the owner of the vehicle within which the immobiliser is fitted to introduce or teach the immobiliser a new security code or codes of a new key or keys or remote transmitter which it should recognise. In other words, provision is made to enable the owner of the immobiliser to enter and store new reference security codes. This is conveniently achieved by providing means for operating the arming circuit in an input mode each time a security code is received by the arming circuit which matches an already stored reference security code. In general, on the arming circuit having armed or disarmed the immobiliser the arming circuit is placed in the input mode for a predetermined period of time, generally, not more than ten seconds. This enables another security code to be entered and stored in memory in the arming circuit as a reference security code. In general, there is a limit to the number of security codes which may be stored in memory of the arming circuit. Typically, not more than ten codes .

While this has the advantage that it enables the user to provide a number of electronic keys or remote transmitters for arming and disarming the immobiliser, it does cause a security risk. For example, a third party who has one of the electronic keys or remote transmitters can readily easily teach the arming circuit a new code of an electronic key in their possession unknown to the vehicle owner. Thus, at a later date the third party could if they wished disarm the immobiliser with their own key. This can be a serious problem when one leaves their car into a garage for servicing or repair.

There is therefore a need for an arming apparatus for arming and disarming a security device, such as, for example, but not limited to a vehicle immobiliser and/or alarm which overcomes these problems.

The present invention is directed towards providing such an arming apparatus.

According to the invention there is provided arming apparatus for arming and disarming a security circuit, the arming apparatus comprising a storing means for storing at least two reference master security codes and a plurality of reference secondary security codes, a receiving means for receiving a security code signal, a reading means for reading the received security code signal from the receiving means, a comparing means for comparing the received security code signal with each reference master security code and with each reference secondary security code, an output means responsive to the comparing means determining that the received security code signal is similar to one of the reference master security codes or the reference secondary security codes for outputting an arming or a disarming signal to the security circuit, a transfer means for transferring a received security code signal to the storing means for storing therein as one of a reference master security code or a reference secondary security code, and a control means for controlling the transfer /means, the control means being responsive to the comparing means having determined that a received security code signal is similar to one of the reference master security codes for operating the apparatus in an input mode for enabling the transfer means to transfer the next received security code signal to the storing means as a reference master security code subject to the number of stored reference master security codes not exceeding a predetermined number of reference master security codes, and for transferring the said next received security code signal to the storing means as a reference secondary security code, on the number of stored reference master security codes being equal to the predetermined number of reference master security codes, and for disabling the transfer means for preventing transfer of the said next received security code signal to the storing means on the comparing means determining that the received security code signal is dissimilar to all of the reference master security codes .

Preferably, a security code signal which is received first by the receiving means is read and stored in the storing means as one of the reference master security code. r In one embodiment of the invention the control means controls the transfer means for limiting the number of received security code signals which may be transferred and stored as reference secondary security codes to a predetermined number of reference secondary security codes .

In one embodiment of the invention the predetermined number of master security codes is two. In another embodiment of the invention the predetermined number of secondary security codes is five.

Preferably, the control means controls the apparatus to operate in an input mode for a predetermined period of time after receiving a security code signal which is similar to a reference master security code.

Preferably, the predetermined period of time does not exceed twenty seconds and advantageously, does not exceed fifteen seconds. Preferably, the predetermined period of time does not exceed ten seconds. Advantageously, the predetermined period of time is approximately five seconds .

In one aspect of the invention the receiving means comprises an electrically conductive contact means for receiving a corresponding contact means for relaying a security code signal to the reading means. Preferably, the electrically conductive contact means comprises a socket for co-operating with a corresponding plug. Alternatively, the receiving means comprises a receiving means for receiving a transmitted signal. Preferably, the receiving means is a radio receiver.

In one particular aspect of the invention the apparatus is for arming and disarming a security circuit provided in a vehicle immobiliser.

In another aspect of the invention the apparatus is for arming and disarming a security circuit provided in a vehicle alarm.

Additionally, the invention provides a vehicle immobiliser comprising a security circuit and arming apparatus for arming and disarming the security circuit, wherein the arming apparatus is arming apparatus according to the invention.

Further the invention provides a vehicle alarm comprising a security circuit and arming apparatus for arming and disarming the security circuit, wherein the arming apparatus is arming apparatus according to the invention.

The invention will be more clearly understood from the following description of a preferred embodiment thereof which is given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a block representation of a circuit diagram of an arming apparatus according to the invention, Fig. 2 is a flow chart illustrating a computer programme which controls the arming apparatus of Fig. 1, and Fig. 3 is a flow chart of a sub-routine of the computer programme of Fig. 2.

Referring to the drawings and initially to Fig. 1 there is illustrated a block representation of a circuit indicated generally by the reference numeral 1 of an arming apparatus according to the invention for a vehicle immobiliser 2 also according to the invention. For convenience, vehicle immobilisers, car alarms whether provided separately or combined, and whether comprising means for operating the central locking system of a vehicle are hereinafter referred to as car immobilisers. The circuitry of the vehicle immobiliser is not illustrated, nor will it be described in detail, ( since such vehicle immobilisers will be well known to those skilled in the art. Briefly, the immobiliser comprises one or more relays through which the ignition circuit of the vehicle is connected, an alarm circuit is connected and a central locking system of the vehicle may be connected. On the vehicle immobiliser being armed by the arming circuit 1 the relays operate to disable the ignition circuit, operate the alarm circuit for monitoring the interior of the vehicle, and operate the central locking system to lock the vehicle. Disarming of the immobiliser 2 by the arming circuit 1 reversed the state of the relays.

The arming circuit 1 comprises a microprocessor 3, which in general, will be shared with the immobiliser 2. A read only memory 4 stores a computer programme which will be described in detail below with reference to Figs. 2 and 3 for controlling the microprocessor 3.

A random access memory 5 stores reference security codes, which are described below, against which received codes are compared by the microprocessor 3. A receiving circuit 6 which may be a radio receiving circuit, or as in this case, a receiving circuit for making electrical contact with an electronic key receives a security code from an electronic key. In this embodiment of the invention the receiving circuit /is provided with a receiving socket with complimentary electrical contacts which are suitable for engaging corresponding electrical contacts on an electronic key of the type sold by Dallas Semi Conductors of the United States of America under the Trade Mark DALLAS P/W Parts Nos. DS 1990A-F3 and DS1233A-10T/R. The received security code is read by suitable reading means in the microprocessor 3. The security code read from the receiving circuit 6 by the microprocessor 3 is compared sequentially with the stored reference security codes stored in the random access memory 5, and on the received security code matching a reference security code a signal is outputted on a line 7 from the microprocessor 3 to the immobiliser 2 for changing the state of the immobiliser 2. If the immobiliser 2 is in the arm state, the signal on the line 7 disarms the immobiliser 2 and vice versa.

Provision as will be described below with reference to the computer programme is provided for permitting the storing of reference master security codes and reference secondary security codes in the random access memory 5. The difference between a master security code and a secondary security code is that where the security code read from the receiving circuit 6 is a master security code, the arming circuit is placed in input mode for a predetermined period of time, in this case, five seconds for enabling the inputting of a new secondary security code which is stored in the random access memory 5 as a reference security code. Under certain circumstances, as will be discussed below, while the arming circuit is in the input mode, a new master security code may also be stored in the random access memory 5 as a reference master security code.

In this embodiment of the invention the maximum number of reference master security codes which may be stored is two and the maximum number of reference secondary security codes which may be stored is five, thus giving a total of seven stored reference codes.

Turning now to Fig. 2 the main computer programme for controlling the arming circuit 1 will now be described. Block 11 starts the computer programme. Block 12 sets M equal to zero. M provides a count of the number of reference master security codes which are stored in the random access memory 5. Block 13 sets S equal to zero. S is a count of the number of reference secondary security codes stored in the random access memory 5.

The computer programme then moves to block 14 which reads any signals which have been received by the receiving circuit 6, and the computer programme moves to block 15. Block 15 verifies firstly if a signal has been read and if no signal has been read returns the computer programme to block 14 to again read the receiving circuit 6. Block 15 also verifies if the signal read is a security code signal, and if not, block 15 returns the computer programme to block 14.

If the signal read by block 14 is verified as being a security code signal, the computer programme moves to block 16. Block 16 reads the first reference security code stored in the random access memory 5. If a reference security code is stored in the random access memory 5, the first reference security code read will be a reference master security code. The computer programme then moves to block 17 which checks if block 16 read a reference security code from the random access memory 5, in other words, block 17 checks if any reference security codes have yet been stored in the random access memory 5. If no codes are stored, in other words, the immobiliser is still in the factory in which it is being produced, the computer programme moves to block 18 which stores the security code which has just been read from the receiving circuit 6 as a reference master security code in the random access memory 5. The computer programme then moves to block 19 which increments M by one indicating that one master security code has been stored in the random access memory 5. The computer programme then returns to block 14.

Should block 17 determine that a reference security code has been read from the random access memory 5, the computer programme moves to block 20. Block 20 compares the received security code with the reference security code. If the two codes compared by block 20 do not match, the computer programme moves to block 21 which reads the next stored reference security code in the random access memory 5 and the computer programme moves to block 22. Block 22 checks if block 21 read a reference security code, in other words, block 22 checks if all the reference security codes stored in the random access memory 5 have already been read and compared in block 20 with the received security code.

If block 22 determines that no reference security code was read by block 21 the computer programme returns to block 14. On the other hand, if block 22 determines that a reference security code was read by block 21, the computer programme is returned to block 20 which compares the received security code which was read from the receiving circuit 6 with the reference security code just read by block 21.

On block 20 determining that the security code received by the circuit 6 matches a reference security code the computer programme moves to block 23. Block 23 checks if the reference security code is a master security code. If the reference security code is not a master security code, the computer programme moves to block 24 which causes the microprocessor 3 to output a signal on the line 7 for arming or disarming the immobiliser 2. The computer programme then returns to block 14. It should be noted here that if the reference security code which matches the security code received by the receiving circuit 6 is not a master security code, then it must be a secondary security code, and accordingly, the only action which the microprocessor 3 carries out under the control of the computer programme is to arm or disarm the immobiliser.

However, on the other hand should block 23 determine that the reference security code is a master security code, then the computer programme moves to block 25 which outputs a signal for arming or disarming the immobiliser 2, in similar fashion to block 24. The computer programme then moves to block 26 which determines if M, in other words the count of the number of reference master security codes stored in the random access memory 5 is less than two. In other words, block 26 checks if the maximum number of two reference master security codes have been stored in the random access memory 5. If M is less than two, in other words, two reference master security codes have not yet been stored in the random access memory 5, the computer programme moves to block 27 which enables transfer means in the microprocessor 3 to transfer and store in , the random access memory 5 the next security code which will be received by the receiving circuit 6 as a reference master security code. The computer programme then moves to block 28 which places the microprocessor 3 in an input mode for enabling reading and storing of the next security code to be read by the receiving circuit 6. Block 28 also calls up an input mode subroutine which will be described with reference to Fig. 3..

On the other hand, should block 26 determine that two reference master security codes have already been stored in the random access memory 5, the computer programme moves to block 29 which checks if S is less than five, in other words, if the number of reference secondary codes stored in the random access memory 5 has reached the maximum of five reference secondary security codes. If the maximum number of five reference secondary codes have been stored in the random access memory 5 the computer programme returns to block 14. If block 29 determines that five reference secondary security codes have not yet been stored in the random access memory 5, the computer programme moves to block 30. Block 30 enables the transfer means in the microprocessor 3 to transfer and store in the random access memory 5 the next security code which will be received by the receiving circuit 6 as a reference secondary security code. The computer programme then moves to block 28 which as already described calls up the input mode sub-routine.

Turning now to Fig. 3 the input mode sub-routine will now be described. Block 40 starts the input mode subroutine. Block 41 sets a timer to time the predetermined period T during which the arming circuit is to be in the input mode. As discussed above, in this embodiment of the invention the predetermined time period T is five seconds. On the timer having been started, the computer programme moves to block 42 which reads signals received by the receiving circuit 6 and the computer programme then moves to block 43. Block 43 checks if a signal has been read by block 42. If no signal has been read by block 42 the sub-routine is returned to block 42. If block 43 determines that a signal has been read, the sub-routine moves to block 44 which checks the signal to verify if it is a security code signal. If the signal read by block 42 is not verified as being a security code signal, the computer programme returns to block 42. Otherwise, the computer programme moves to block 45 which checks if the microprocessor 3 is enabled to store a reference master security code. If the microprocessor 3 is enabled to store a reference master security code, then the computer programme moves to block 46 which stores the .· security code received by the receiving circuit 6 as a reference master security code in the random access memory 5. The computer programme then moves to block 47 which checks if block 46 has stored the received code as a reference master security code. If the received code has been stored as a reference master security code the computer programme moves to block 48 which increments M, namely, the count of reference master security codes stored in the random access memory 5 by one. The computer programme then moves to block 49 which returns control of the microprocessor 3 to block 14 of the main computer programme of Fig. 2.

Should block 45 determine that the microprocessor 3 is not enabled for transferring and storing a master security code, then the sub-routine moves to block 50 which stores the security code received by the receiving circuit 6 as a reference secondary security code in the random access memory 5. It should be noted here that once the input mode sub-routine is called up, the microprocessor 3 is enabled to store either a reference master or a secondary securing code, and accordingly, if the microprocessor 3 is not enabled to store a reference master security code then it must be enabled to store a reference secondary security code. After block 50 the computer programme moves to block 51 which checks if block 50 has stored the reference secondary security code. If so, the computer programme .moves to block 52 which increments S which is the count I of reference secondary security codes stored in the random access memory 5 by one and the computer then moves to block 49 which returns control of the microprocessor 3 to block 14 of the main computer programme.

In the event that blocks 47 and 51 determine that the security code has not been stored as a reference master or secondary security code as the case may be, the subroutine moves to block 53 which checks if the timer has timed the predetermined time period T of five seconds.

If the timer has not yet timed the five second period, in other words, if the arming circuit has not been in the input mode for five seconds, then the sub-routine returns to block 42. On the other hand, if block 53 determines that the arming circuit has been in the input mode for five seconds or more, then the subroutine moves to block 54 which returns control of the microprocessor 3 to block 14 of the main computer programme.

Accordingly, from the above, it will be clear that new reference security codes can only be entered and stored in the random access memory 5 if a master security code has been received by the receiving circuit 6.

Accordingly, provided the owner of the vehicle retains /the electronic keys or the remote transmitters which retain the master security codes safely, there can be no danger of a third party entering a new security code into the random access memory 5. In other words, there can be no danger of a third party teaching the arming circuit 1 a new security code. However, since the arming circuit 1 has provisions for enabling one new master security code to be entered and stored as a reference master security in the random access memory 5, it is important that the two master security codes should be entered and stored in the random access memory 5 as soon as possible. Preferably, the storing of the two reference master security codes should be carried out in the factory where the immobiliser is being manufactured.

The advantages of the invention are many, however, the main advantage of the invention is that provision is made to allow an owner of a vehicle to enter one or more secondary security codes which match the stored code in a new electronic key or a remote transmitter which may be given to a third party who requires access to the vehicle, for the purpose of repairing, servicing and the like. With such a secondary electronic key or remote transmitter, there is no danger of the third party entering and storing a new reference security code.

While the arming circuit of the arming apparatus has been described for use with a vehicle immobiliser, the arming circuit may be used for arming any other security device, indeed, it may be used for arming a burglar alarm in a domestic dwelling, office, factory or other building, or any other type of security device. While in the arming circuit of the invention provision is made for storing two reference master security codes and five reference secondary security codes, provision may be made for storing any number of reference master security codes from two upwards and likewise any number of reference secondary security codes from two upwards.

Additionally, while a predetermined period of time T during which the arming circuit is in the input mode has been described as being five seconds, the time period during which the arming circuit is in the input mode may be greater than or less than five seconds.

While the security codes for operating the arming circuit have been described as being stored in an electronic key or a remote radio transmitter, security codes for operating the arming circuit may be stored in any other suitable storing means, and an appropriate receiving circuit would then be provided. t The invention is not limited to the embodiment hereinbefore described which may be varied in construction and detail.

Claims

1. Arming apparatus for arming and disarming a security circuit, the arming apparatus comprising a storing means for storing at least two reference master security codes and a plurality of reference secondary security codes, a receiving means for receiving a security code signal, a reading means for reading the received security code signal from the receiving means, a comparing means for comparing the received security code signal with each reference master security code and with each reference secondary security code, an output means responsive to the comparing means determining that the received security code signal is similar to one of the reference master security codes or the reference secondary security codes for outputting an arming or a disarming signal to the security circuit, a transfer means for transferring a received security code signal to the storing means for storing therein as one of a reference master security code or a reference secondary security code, and a control means for controlling the transfer means, the control means being responsive to the comparing means having determined that a received security code signal is similar to one of the reference master security codes for operating the apparatus in an input mode for enabling the transfer means to transfer the next received security code signal to the storing means as a reference master security code subject to the number of stored reference master security codes not exceeding a predetermined number of reference master security codes, and for transferring the said next received 5 security code signal to the storing means as a reference secondary security code, on the number of stored reference master security codes being equal to the predetermined number of reference master security codes, and for disabling the transfer means for 10 preventing transfer of the said next received security code signal to the storing means on the comparing means determining that the received security code signal is dissimilar to all of the reference master security codes . 15

2. Apparatus as claimed in Claim 1 in which a security code signal which is received first by the receiving means is read and stored in the storing means as one of the reference master security code.

3. Apparatus as claimed in Claim 1 or 2 in which the 20 control means controls the transfer means for limiting the number of received security code signals which may be transferred and stored as reference secondary security codes to a predetermined number of reference secondary security codes . 25

4. Apparatus as claimed in Claim 3 in which the predetermined number of reference secondary security codes is five.

5. Apparatus as claimed in any preceding claim in which the predetermined number of reference master security codes is two.

6. Apparatus as claimed in any preceding claim in 5 which the control means controls the apparatus to operate in the input mode for a predetermined period of time after receiving a security code signal which is similar to one of the reference master security codes.

7. Apparatus as claimed in any preceding claim in 10 which the receiving means comprises an electrically conductive contact means for receiving a corresponding contact means for relaying a security code signal to the reading means .

8. Apparatus as claimed in Claim 7 in which the 15 electrically conductive contact means comprises a socket for co-operating with a corresponding plug.

9. Apparatus as claimed in any of Claims 1 to 6 in which the receiving means comprises a receiving means for receiving a transmitted signal. 20 10. Apparatus as claimed in Claim 9 in which the receiving means is a radio receiver. 11. Apparatus as claimed in any preceding claim in which the apparatus is for arming and disarming a security circuit provided in a vehicle immobiliser. I k 12. Apparatus as claimed in any preceding claim in 5 which the apparatus is for arming and disarming a security circuit provided in a vehicle alarm. 13. An arming apparatus substantially as described herein with reference to and as illustrated in the accompanying drawings.

10. 14. A vehicle immobiliser comprising a security circuit and an arming apparatus for arming and disarming the security circuit, wherein the arming apparatus is an arming apparatus as claimed in any preceding claim.

11. 15 15. A vehicle alarm comprising a security circuit and an arming apparatus for arming and disarming the security circuit, wherein the arming apparatus is an arming apparatus as claimed in any of Claims 1 to 13.

12. 16. A vehicle immobiliser substantially as described

13. 20 herein with reference to and as illustrated in the accompanying drawings .