WO1997031347A1

WO1997031347A1 - Key security system

Info

Publication number: WO1997031347A1
Application number: PCT/GB1997/000513
Authority: WO
Inventors: Richard James Cowell; Michael Peter Hamilton
Original assignee: Volumatic Limited
Priority date: 1996-02-22
Filing date: 1997-02-24
Publication date: 1997-08-28
Also published as: GB9603750D0

Abstract

A key operated security system has a key (16) which carries a microchip containing a security code formed by a number of digits. A control unit (12) has a control circuit (100) and a socket (104) to receive the key to connect the microchip of the key to the control circuit. The control circuit senses the presence of the key and reads the security code in the key microchip and compares this with a security code previously stored in a memory (RAM) of the control circuit. If the two codes are identical then the control circuit generates a disarming signal which disarms an alarm circuit coupled to the control circuit, or alternatively or additionally, which moves a lock of e.g. a safe door into an unlocking attitude. To programme the control circuit with the security code power is removed from the control circuit to clear the RAM. When power is re-applied the control circuit activates the alarm until a key is inserted in the socket. The security code pre-stored in the key microchip is then read into the control circuit RAM and at the same time the alarm is inhibited. With the key then removed, remote sensors (14) attached to the control unit generate a trigger signal in response to a sensed condition such as removal of a garment or forced opening of the safe door and cause activation of the alarm circuit.

Description

KEY SECIIRTTY SYSTEM

The present invention relates to a security system.

Various types of security systems are available for protecting personal valuables, garments and other merchandise from theft. Systems such as those used in shops normally have a central alarm unit which is connected to various security devices which trip the alarm when tampered with. Once the alarm is activated, the system can only be deactivated by use of a key. In the case of, for example, a hotel room safe, a key is required to lock and unlock the safe. However, the keys have to be provided by the manufacturer and, if lost, can cause considerable problems as a result of the delays which would be incurred in obtaining a replacement key.

The present invention seeks to provide an improved security system.

Accordingly, the present invention provides a security system comprising:

key means having electronic key store means, said key store means having stored therein a key security code comprising a plurality of digits;

and a control unit having a control circuitand socket means for receiving said key means;

wherein:

said socket means and said key mean are adapted such that insertion of said key means into said socket means connects said electronic key store means to said control circuit;

said control circuithas:

read means for reading said key security code in said electronic key store means;

control store means for storing said key security code; monitoring means for monitoring the presence or absence of said key means in said socket means;

and comparing means for comparing said security code stored in said control store means with said key security code;

wherein said control circuit is operable in a first, armed mode and a second, learning mode;

wherein, in said learning mode said control store means is empty and said read means is operable to read the key security code of a said key means inserted in said socket means and store said key security code in said control store means, said control circuit thereby switching into said armed mode;

and wherein in said armed mode:

said monitoring means is operable to monitor the presence or absence of a said key meansin said socket means;

and said comparing means is operable to compare the key security code of said key means with the security code previously stored in said control store means in said learning mode and to generate a disarming signal in response to a comparison of said key security code and said security code stored in said control store means indicating the presence of a valid key means.

The present invention is further described hereinafter, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of one preferred form of security system according to the present invention;

Figure 2 is a circuit diagram of a main control circuit ofthe system of Figure 1 ; Figure 3 is a circuit diagram of a trigger circuit for the control circuit of Figure 2;

Figure 4 is a circuit diagram of an alarm circuit for the control circuit of Figure 2;

Figure 5 is a circuit diagram of a power supply unit for the security system;

Figure 6 is a flow chart illustrating the stages of operation ofthe system;

Figure 7 is a diagrammatic view of a second embodiment ofthe invention; and

Figure 8 is a flow chart illustrating the stages of operation ofthe system of Figure 7.

Referring firstly to Figure 1, this is a general view of a first preferred form of security system 10 for use in shops to protect merchandise. The system has a main alarm unit 12, a trigger for the unit in the form of a garment grip 14 and a disarming key 16. The garment grip 14 is advantageously of the type disclosed in the patentee's prior patent GB 2,257,462 and carries a microswitch which is tripped when the grip is removed from a garment. The microswitch is closed by the presence of a garment and is opened when the garment is removed. The microswitch is connected to a plug 18 by way of a suitable flex 20, the plug 18 engaging in one of several sockets 22 in the main alarm unit 12. A respective garment grip 14 can be connected to each ofthe available sockets 22.

Each plug 18 is conveniently a telephone style (FCC) connector which is connected to the gripper 14 by a four-core cable. Two ofthe cores are connected to the microswitch whilst the remaining two cores form a tamper loop which is used to trigger the alarm unit if the flex 20 is tampered with.

The disarming key 16 has a number of pins 24 which may conveniently be formed by printed circuit strips on one or both sides ofthe key. These pins 24 connect with a microchip 17 in the key in which a four digit code is pre-programmed. The numbered digits in the code may of course be varied. In the main control unit 12, each socket 22 has an associated trigger circuit (Figure 3). These are identical and therefore only one is shown in Figure 3 and described here. Socket 22 has four pins 1 to 4. Pins 1 and 2 of socket 22 are connected to respective inputs 25a, 25b of an EXCLUSIVE-NOR gate 25. The output of gate 25 is connected to the base of a transistor 26 connected between rails 28 and 30. The rail 28 is connected to a positive voltage supply (typically 9v) through a resistance in the main control circuit 100 whilst the rail 30 is connected through a normally on transistor 110 of the main control circuit 100 to a zero voltage line 114. The collector of transistor 26 is connected to rail 30 through an LED 32 on the main alarm unit. Each trigger circuit has its own visual indicator or LED 32 to indicate clearly which ofthe garment grips 14 and/or flex 20 has been tampered with. The plug 18 associated with the socket 22 has four pins connecting with pins 1 to 4 of the socket 22. When the plug 18 is engaged in the socket 22 pins one and four of the socket 22 are connected through the tamper loop whilst pins two and three are connected to the microswitch which is closed when the gripper 14 is connected to a garment. In this condition, both inputs ofthe gate 25 are at logic 1 condition and its output is therefore also at logic 1 , maintaining transistor 26 off.

The control circuit 100 of Figure 2 has a microprocessor 102, eight pins of which are connected to a key socket 104 for receiving the pins 24 of key 16.

The microprocessor 102 has means 152 for reading the key security code of a key inserted in the socket 104, a store means (RAM) 154 for storing a key security code, monitoring means 156 for scanning the socket 104 and monitoring the presence or absence of a key in the socket and a comparator 158 for comparing the security code stored in the store 154 with the key security code read from the key inserted in the socket 104.

The microprocessor is also connected through several transistors 106, 108 and 110 to the rails 28, 30 of the trigger circuit 31 of Figure 3. It is also connected via a transistor 112 to one voltage rail of the alarm circuit 200 of Figure 4. The emitter of transistor 112 is in fact connected to a zero volt line 114 whilst the collector is connected to the voltage rail 202 of the alarm circuit 200. The alarm circuit 200 has a triangular wave form generator 204, formed by two operational amplifiers 206, 208, and a voltage controlled oscillator 210 which is driven by the triangular wave form generated by the generator 204. The voltage controlled oscillator 210 in turn drives an audible alarm such as a speaker 212. However, when transistor 1 12 ofthe control circuit 100 is off, the voltage rail 202 is high, disabling the alarm circuit. Under normal conditions, in the absence of an alarm transistor 112 is off.

In operation, as a garment is removed from the grip 14, the microswitch in the grip is opened. This open circuits the input 25b of gate 25, generating a logic 0 signal at the output of gate 25. A latch formed by a feedback diode 29 serves to latch the gate in this state, maintaining the logic 0 output so that if the microswitch were to be closed or the loop reconnected, the gate output would remain at logic 0.

The logic 0 signal at the output of gate 25 turns transistor 26 on, energising the LED 32 on the alarm unit panel to indicate which ofthe garment grips has been tampered with.

The turning on of transistor 26 turns on transistor 108 ofthe control circuit 100 and applies a signal to pin eight ofthe microprocessor to indicate that an alarm condition has occurred. The microprocessor 102 is normally maintained in a "sleep" condition to conserve battery power and is raised to an active condition for a short period of time, e.g. every 2.5 seconds. During its active period LEDs 116 and 118 are flashed at periodic intervals, e.g. every 5 seconds to indicate that the circuit is still operational.

When an alarm condition results in transistor 108 being turned on, as well as applying an alarm signal to pin eight ofthe microprocessor, it also turns on transistor 106 which applies a signal to pin twenty-eight ofthe microprocessor to switch the latter from its normal "sleep" mode into an active mode. If this did not occur then the microprocessor would not activate the alarm until perhaps several seconds later when it switched from its "sleep" condition to its active condition as described above. Once raised into its active condition by the signal from transistor 106, the microprocessor then, as a result of receipt ofthe alarm signal from pin eight, turns transistor 112 on which pulls the voltage rail 202 of the alarm circuit 200 approximately to zero volts, activating the alarm circuit 200 and resulting in the speaker 212 being driven by the voltage controlled oscillator 210 to sound an alarm.

A power supply circuit 300 for the system is shown in Figure 5 and has a socket 302 in a battery compartment for connection to a battery. It also has a socket 304 for connection to a mains driven DC power supply. The power supply for the system may either be battery driven or powered from the mains supply and in the latter case a rechargeable battery may be provided for socket 302 as a back-up supply.

The power supply circuit 300 also has a switch 301 which enables power to be disconnected from the control circuit 100.

The power supply provides 9v and 5v supply rails 302, 305 for the system.

The battery compartment has a tamper switch 120 (Figure 2) which is connected in the control circuit 100 and which is normally open. If the cover ofthe battery compartment is removed then the tamper switch 120 is closed. This connects the collector of transistor 110 to the base of transistor 108, turning the latter on (in the absence ofthe key) and applying an alarm signal to pin eight of the microprocessor 102, activating the alarm circuit 200 as described above.

A low battery voltage detection circuit 400 is also provided. This periodically monitors the voltage on the supply rail 302. If this voltage drops below a reference level set by a zener diode 404 then it trips an operational amplifier 406 which applies a signal to the microprocessor indicating that the battery voltage is low.

Referring now to the key 16, as has been mentioned previously this includes a microchip which is in the form of a ROM which is normally pre-programmed with a four digit code by the manufacturer or supplier ofthe system. The number of digits can, of course, be varied.

Referring now to the system flow chart of Figure 6, when the above-described preferred form of security system is first used a battery is connected to the battery socket 302. It will be appreciated that, equally, DC power could be supplied from a mains adaptor and the following description applies equally where this is the case. When the battery is first connected it activates the main control circuit 100 which immediately goes into an alarm state, energising the alarm circuit 200 to sound an alarm. This is to prompt the user to insert the disarming key 16 in the socket 104 ofthe main control circuit 100. The microprocessor 102 continually tests to see if the key is present and continues to sound the alarm in the absence of the key.

When the key 16 is inserted into the socket 104, this is detected by the microprocessor which immediately turns off transistor 112 to disable the alarm circuit 200. Power is supplied to the microchip in the key via pins 7 and 8 of socket 104. An interrogation signal from the microprocessor 102 is applied periodically to pin 6 of socket 104 and when a key is present this results in the microchip in the key transmitting its four digit code in serial data form to the microprocessor via pin 6 of socket 104. The absence of a key is treated as a zero signal on pin 6. The microprocessor also reads the four digit code which is stored in the memory in the key and itself stores the code so that it will then be able to recognise and distinguish this particular disarming key 16 from any other keys that might be inserted in its place.

With the key 16 inserted in the socket 104, the security system is disarmed and garments can be added to or removed from grips 14 which can be plugged into or disengaged from the various sockets 22.

When the key 16 is removed from the socket 104 the security system becomes armed and operates as described above. If any ofthe grips 14 or flexes 20 are tampered with then an alarm is sounded as described above.

If a condition occurs, for example removal of a garment from a grip 14, which triggers the alarm then the alarm can only be cancelled by inserting the correct disarming key 16 in the socket 104. The microprocessor continually checks the socket 104 to detect the presence or absence of the key. When the key is inserted the microprocessor compares the four digit code in the key with its previously stored four digit code and when the comparison is successful it disarms the system.

The above-described system has the great advantage that if the disarming key 16 is lost or damaged it can easily be replaced and the replacement key does not have to have stored in its memory the same four digit code as the original key. In such an event, the power supply to the system is removed. As a result, the four digit code which was originally stored in the microprocessor 102 is lost. The power supply can then be reconnected with the new key inserted or the new key then inserted in the socket 104. The four digit code in the new key is then read and stored by the microprocessor in the set up procedure as described above. A number of different disarming keys having different codes can therefore be supplied with the system so that, in the event ofthe first-used key being lost or damaged it can be replaced and the system set up and working in a matter of minutes.

A further preferred form of the system is shown diagrammatically in Figure 7. Like parts with those in Figures 1 to 6 are given like reference numbers. Here, the invention is applied to a security lock which has a control circuit 100 and power supply circuit 300. If this is applied, for example, to a safe 504 such as a safe used in a hotel room, the output of transistor 112 ofthe control circuit 100 can be applied to a lock circuit 500 for the safe door 502.

As is explained above, if the power supply to the circuit 100 is removed, any previously stored code in the microprocessor 102 is lost. A new key can then be inserted in the socket 104 and the power supply reconnected. The code in the new key is read and stored by the microprocessor in the procedure previously described.

Power to the control circuit 100 can be controlled by a microswitch 600 actuated by opening and closing the safe door. When a guest first checks into the hotel room, the safe door is open. The micro switch is connected such that with the door open the power supply to the control circuit 100 is disconnected. The guest inserts a key into the socket 104 and closes the door. Closing the door trips the microswitch 600 to connect the power supply to the control circuit 100. The microprocessor 102 then reads the code stored in the key microchip and stores it. The presence or absence ofthe key is monitored by application of an interrogation signal from the microprocessor 102 to pin 6 of socket 104, as also previously described. When the key is removed, the microprocessor 102 senses this removal and generates a signal which activates the lock on the safe. When the key is re-inserted, the microprocessor 102 again detects the presence of a key and provided the four digit code pre-programmed in the key matches the code previously stored by the microprocessor then the latter generates a signal which deactivates the safe lock. The latter can be in the form of a simple solenoid controlled bolt and such types of locks are well known in the art. Figure 8 shows a flow chart illustrating the stages of operation ofthe system of Figure 7.

It is of course possible that the control circuit will be powered by battery but it is expected that with an application such as described above, the power will be supplied from the main supply.

Claims

1. A key operated security system (10) comprising:

key means (16) having electronic key store means(17), said key store means having stored therein a key security code comprising a plurality of digits;

and a control unit (12) having a control circuit (100) and socket means (104) for receiving said key means (16);

wherein:

said socket means (104) and said key means(16) are adapted such that insertion of said key means into said socket means connects said electronic key store means to said control circuit (100);

said control circuit (100) has:

read means (152) for reading said key security code in said electronic key store means;

control store means (154) for storing said key security code;

monitoring means (156) for monitoring the presence or absence of said key means (16) in said socket means;

and comparator means (158) for comparing said security code stored in said control store means (154) with said key security code;

wherein said control circuit (100) is operable in a first, armed mode and a second, learning mode; wherein, in said learning mode said control store means (154) is empty and said read means (152) is operable to read the key security code of a said key means (16) inserted in said socket means (104) and store said key security code in said control store means (154), said control circuit (100) thereby switching into said armed mode;

and wherein in said armed mode:

said monitoring means (156) is operable to monitor the presence or absence of a said key means (16) in said socket means (104);

and said comparator means (158) is operable to compare the key security code of said key means (16) with the security code previously stored in said control store means (154) in said learning mode and to generate a disarming signal in response to a comparison of said key security code and said security code stored in said control store means (154) indicating the presence of a valid key means.

2. A key operated security system as claimed in Claim 1 wherein said control store means (154) is cleared in response to removal of power from said control circuit (100);

and said control circuit (100) enters said learning mode in response to the supply of electrical power to said control circuit.

3. A key operated security system as claimed in Claim 2 wherein said control circuit (100) is coupled to a power supply source by switch means (301).

4. A key operated security system as claimed in Claim 3 further comprising lock means (500) switchable between a first state wherein said lock means is retained in a locking attitude and a second state wherein said lock means is retained in an unlocking attitude;

and wherein said control circuit (100) is coupled to said lock means (500) and said lock means is switchable from said locking attitude to said unlocking attitude in response to receipt of said disarming signal.

5. A key operated security system as claimed in Claim 3 or 4 for controlling a door

(502) wherein said switch means (301) is actuated in response to opening of said door to disconnect power supply to said control circuit (100) thereby to clear said control store means (154) and is actuable in response to closing of said door (502) to connect power to said control circuit (100) thereby to switch said control circuit into said learning mode.

6. A key operated security system as claimed in any ofthe preceding claims wherein said control unit (12) further comprises:

an alarm circuit (200) for generating an alarm signal;

wherein said system further comprises:

sensor means (14) remote from said control unit (12) for triggering an alarm trigger signal in response to changes in a sensed condition;

and wherein said control circuit (100) is operable in the absence of said disarming signal to activate said alarm circuit (200) in response to receipt of said alarm trigger signal.

7. A key operated security system as claimed in Claim 6 wherein sai d sensor means .( 14) is adapted to be attached to a product (90) and said sensed condition is removal of said product from said sensor means.

8. A key operated security system as claimed in Claim 6 or 7 wherein said control circuit has a trigger circuit (31) having an output (28) for applying said alarm trigger signal to said control circuit (100), said trigger circuit having latch means (29) for maintaining said alarm trigger signal at said output regardless ofthe subsequent state of said sensed condition.

9. A key operated security system as claimed in Claim 7 or 8 having a plurality of said sensor means (14), each of which is coupled to a respective said trigger circuit (31).

10. A key operated security system as claimed in any of the preceding claims further comprising a battery operated power supply unit (300) for supplying electrical power to said control circuit (100);

wherein said unit (300) has a compartment for receiving one or more batteries;

said compartment has a cover and switch means actuated by removal of said cover to generate an alarm signal;

and wherein said control circuit is operable in the absence of a disarming signal to activate said alarm circuit (200) in response to receipt of said alarm signal.