GB2328303A - Programmable security device - Google Patents

Abstract

A security device 50 for inhibiting unauthorised tampering with electrical and/or electronic apparatus 40 comprises: sensing means for sensing tampering with the apparatus and/or the device; receiver means 52 for receiving broadcast signals from a remote transmitter 70; and a microprocessor operable to initiate an alarm in accordance with its programming and in response to an indication from the sensing means that tampering has been sensed, and being programmable by means of the broadcast signals. The security device may include vibration detection means and/or relative movement detection means for detecting tampering with the apparatus casing. The security device may be programmed remotely to suit a particular application. Various features directed towards improving the security of the remote programming link are described, and a particular embodiment is adapted for mounting in an expansion port of a computer.

Description

A PROGRAMMABLE SECURITY DEVICE The present invention relates to a security device for inhibiting unauthorised tampering with electrical and/or electronic apparatus, a security device in combination with electrical and/or electronic apparatus, a security device in combination with a programming module, and a security system.

In particular, although not exclusively, the present invention relates to a security device for inhibiting unauthorised tampering with a computer or an associated peripheral device.

Theft of electrical and/or electronic apparatus, in particular the theft of computers, their peripherals, or internal components such as chips, hard disks or other memory is a major problem.

A wide variety of security devices, attempting to solve this problem, are known, incorporating a wide range of tamper sensing means. These tamper sensors include vibration or movement sensors able to detect movement of the protected apparatus and/or the security device attached to it, and case tamper switches incorporating micro switches or photo detectors, activated when the case of the protected apparatus is partially opened or removed, or when an attempt is made to separate the security device from the protected apparatus. Security devices are also known which transmit an alarm signal via a network link or a dedicated hard wired link to an alarm system when the tamper sensor is activated. Typically, these devices are set or switched on by entering a code via a keypad or by operating a keyswitch.

In the Applicant's co-pending International Patent Applications ~~~~~~~~~~ and ~~~~~~~~~~ there are described improved security devices, which overcome some of the problems with the prior art arrangements. These improved devices include arrangements in which vibration detection is enabled only when external power supply to the protected apparatus or security device is disconnected,to prevent inadvertent triggering of the device during the normal times of use of the apparatus, and in which case tamper switches make electrical contact to the case of the protected apparatus, the alarm being triggered not just when this contact is broken, but also when its contact resistance changes. The improved security devices also include arrangements incorporating memory means, which stores data representing a unique address, or identity. This data is encoded and transmitted when tampering is detected, to a remote sensor in order to identify the apparatus being interfered with. Devices are also described incorporating memory means in the form of DIP switches, providing the advantage that the address may be altered. However, a disadvantage with these arrangements is that to alter the address, one needs to open the casing of the apparatus and/or the security device to access the DIP switches. Some of the described arrangements incorporate microprocessors, providing the advantage that the address stored in memory, and the tamper sensing means sensitivity, may be programmed.

However, at some time after attaching such a device to the apparatus it is to protect, it may be desirable to alter the programming of the microprocessor, for example to change the address, or the tamper sensing means sensitivity. If this reprogramming necessitates removal of the device from the protected apparatus, or the opening of the casing of the protected apparatus or the security device, for example to access an internal connector or interface to the microprocessor and its associated circuitry, then, just like the manual setting of DIP switches, it will still be inconvenient and time consuming. This is a problem especially in security systems incorporating large numbers of security devices, protecting a large number of computers and associated peripheral devices, in, for example, a large office block.

It is an object of one aspect of the present invention to provide a security device comprising a microprocessor, which is programmable in a convenient way.

It is an object of embodiments of the present invention to provide a security device incorporating a microprocessor which is programmable in a convenient and secure way, ie. unauthorised programming or reprogramming is inhibited.

According to a first aspect of the present invention there is provided a security device for inhibiting unauthorised tampering with electrical and/or electronic apparatus, comprising: sensing means for sensing tampering with said apparatus and/or said device; receiver means for receiving broadcast signals from a remote transmitter; and a microprocessor connected to said sensing means and said receiver means, said microprocessor being operable to initiate an alarm in accordance with its programming and in response to an indication from said sensing means that tampering has been sensed, said microprocessor being programmable by means of said broadcast signals.

By "remote" it is meant that there is no direct physical contact between the receiver means and the transmitter.

The sensing means may take a wide variety of forms. For example it may comprise a movement or vibration detector able to detect movement of the apparatus or the device, and/or a tamper switch arranged to be activated when the casing of the apparatus is opened or removed, either completely or partially, or when an attempt is made to separate the security device from the apparatus it is arranged to protect. The sensing means could alternatively, or in addition, comprise a passive infrared receiver (PIR) arranged to detect people in the vicinity of the device, or may comprise any other suitable detection device. It will be apparent that the sensing means may comprise a single detector or a plurality of similar or different detectors.

By determining alarm initiation not just in accordance with signals from the tamper sensing means, but also in accordance with the programming of the microprocessor, this first aspect of the present invention provides the advantage that a wide variety of alarm configurations are possible with the same hardware. For example, the microprocessor may be programmed to look at the duration and/or the magnitude of the indicative signal from the tamper sensing means, apply programmed criteria, and so decide whether or not to initiate the alarm. By altering the programming of the microprocessor, the sensitivity of the device to tampering may be altered to suit the particular application. The microprocessor may be programmed to ignore the signal from the tamper sensor during certain periods of time, or for example while the microprocessor is also receiving an indication that power is being supplied to the device or to the apparatus from an external source such as the mains. Thus, all or part of the tamper sensing means may be "disabled" during normal periods of operation of the apparatus. The device may comprise a number of different sensing devices, each connected to the microprocessor which may be programmed to "listen" to different sensing devices at different times or according to current conditions.

The fact that the microprocessor is programmable by means of broadcast signals facilitates programming.

No casing need be opened or removed, and in certain embodiments, the device need not be unattached from the protected apparatus in order to be programmed.

Thus the device can be "factory fitted" to the apparatus before it is sent to the end user, and then conveniently programmed after delivery to suit the particular application.

Re-programming at a later date, for example to change the sensitivity of the device to a particular element of the tamper sensing means, is also facilitated.

An alternative solution to this problem of facilitating programming or re-programming in situ could be to provide an accessible connector on an exposed surface of the security device for direct connection of a programming module/unit to the microprocessor and its associated circuitry.

However, the security device according to the first aspect of the present invention provides the advantage that no such connector need be provided.

This improves case integrity, makes it easier to satisfy EMC testing criteria (any connector/socket into the security device must be tested) and inhibits unauthorised tampering or re-programming of the microprocessor.

No direct access need be provided to the microprocessor and its associated circuitry, giving an unauthorised user no opportunity to try to disable the device, for example, by applying high voltage across the microprocessor circuitry, and providing a very high degree of immunity against unauthorised programming. Providing no direct access makes it more difficult to damage the microprocessor and/or its associated circuitry.

The security device may be adapted to restrict the range of positions of the remote transmitter from which the broadcast signals can be received by the receiver means.

This provides the advantage of further inhibiting unauthorised programming, attempting, for example, to disrupt the operation of the security device or disable the tamper sensing means.

For example, the receiver means may be set in a recess or cup in the casing of the security device so that the transmitter must be within the limited region of direct line of sight to the receiver means defined by the geometry of the recess in order for the broadcast signals to be received.

The receiver means may itself be highly directional, able to receive incoming broadcast signals from only a narrow range of angles.

A programming unit comprising the remote transmitter, and the security device may be cooperatively adapted to inhibit unauthorised transmission of signals to the receiver means. For example, the remote transmitter may be mounted on a protrusion of the programming unit, the protrusion being adapted to be received in a recess in the casing of the security device to bring the remote transmitter into line-of-sight with the receiver means.

The security device may further comprise means for providing an indication of the state of the apparatus, for example, whether the apparatus is switched on or off, is hot or cold, is fully operational or is in an "idle" mode in which it is consuming reduced power. The microprocessor may then be able to monitor the signal from the state indicating means, along with the signal from the tamper sensing means and to initiate an alarm accordingly.

For example, the signal from a vibration detector may be ignored until the protected apparatus is switched off. Alternatively, the microprocessor may be programmed to have a high sensitivity to the vibration detection means while the protected apparatus is switched off, and a reduced, but non zero sensitivity when the apparatus is in use (i.e.

switched on).

The security device may comprise a battery for supplying electrical power to operate the security device circuitry, thus enabling the security device to inhibit tampering with the apparatus when all external power supply has been disconnected. The battery may be rechargeable, and the security device may be arranged to charge the battery while power is being supplied from an external source.

Advantageously, the security device may comprise transmission means for transmitting an alarm signal for reception at a remote sensor in response to the microprocessor initiating an alarm. The remote sensor may be disguised, or alternatively may be highly visible to act as a deterrent to tampering.

Advantageously the alarm signal may be a radio frequency signal, modulated in a suitable manner.

The security device may comprise memory means storing identification data (i.e. an address) and encoding means to encode the transmitted alarm signal according to this data to allow the remote sensor, or a control unit connected to this sensor, to identify the device from which the alarm signal is being sent.

Advantageously, this memory means may be programmable by means of the broadcast signals. Thus, a number of security devices factory fitted" to various pieces of apparatus may be individually programmed after delivery, with ease, to give each device a unique identity or address. A security system incorporating a remote sensor may therefore be able to identify exactly which device is being tampered with when it receives an alarm signal.

Alteratively, groups of security devices protecting similar or related pieces of equipment may be given the same address/identity, for example the same identity may be given to all devices in a particular office, room, or on a particular floor. The security system may keep a log of all security devices under its watch, containing the identity/address of each security device together with its location.

The security device may comprise means for connecting it to an external supply of electrical power to operate the circuitry and/or recharge its internal battery. By "external" it is meant that the power is supplied from means not comprised in the security device. For example, the security device may comprise a transformer and means for connecting it directly to the mains supply, or alternatively may comprise means for connection to an external transformer to receive DC electrical power at a reduced voltage.

The device may further comprise means for connecting it to the apparatus to supply electrical power to operate the apparatus. Thus, the security device may be in- line between the apparatus and an external power supply such as the mains.

Alternatively, the device and apparatus may be powered independently.

In other arrangements, the external supply of electrical power to the security device may be from or via the protected apparatus. This may provide the advantage that when external power supply to the apparatus is switched off or disconnected, the external power supply to the security device is also disconnected.

Advantageously, the security device may comprise external power supply monitoring means, connected to the microprocessor and able to provide a monitoring signal to the microprocessor, indicative of whether external power is being supplied to the security device or not. Thus, for example, when the microprocessor receives a monitoring signal indicative of external power supply being disconnected, it may change its sensitivity to the tamper sensing means, initiate an alarm signal, or log the event.

The microprocessor may only be programmable by means of broadcast signals while the device is connected to an external supply of electrical power, ie. it is not programmable by broadcast signals when the device is being powered by its internal battery.

This provides a high degree of immunity against tampering and unauthorised programming. For example, if the protected apparatus and security device are disconnected from their mains supply at night, and the microprocessor is programmed to respond to this act by switching to high sensitivity vibration detection and to enable a PIR, then it is not possible for a wouldbe intruder to disable or re-program the security device by transmitting a signal from a safe distance away.

One of the ways of achieving this desirable feature is to disable the receiver means while external power supply is not connected. This may provide the further advantage that power consumption of the security device may be reduced, thereby extending battery life.

The security device may also incorporate means for mounting it to the apparatus to be protected. In particular, although not exclusively, for devices intended for attachment to the outside of apparatus, this mounting means may take the form of velcro TM strips, or strips of strong double sided adhesive tape stuck to the security devices casing. Such arrangements facilitate attachment of the security device and are particularly relevant to in-line devices.

Alternatively, the security device may be adapted for mounting in an expansion port of a computer or associated peripheral device. This is particularly, although not exclusively, applicable to embodiments in which the security device receives external power supply from the protected apparatus (ie. in this case the computer or peripheral).

Advantageously the security device may be arranged to be programmed only by broadcast signals in the optical frequency range (approximately 1014 to 1015 Hz), or alternatively in the infrared frequency range (approximately 1011 to 1014 Hz).

Of course, other frequencies could be used, but signals in these frequency ranges (with short wavelengths in the range 3mm to 0.3cm) provide the advantage that reflection from walls and defraction around objects such as office furniture is minimal, thereby further restricting the range of positions from which broadcast signals to program the microprocessor can be transmitted and received by the security device. This further inhibits unauthorised tampering. In general, for security, the shorter the wavelength the better.

Also, unlike the case with ultrasonic signals and radio frequency transmissions, the beam of optical or infrared signals broadcast to the receiving means may easily be kept narrow; stray broadcasts can be minimised, making it difficult for a would be tamperer to "grab" programming signals and so learn the programming structure or protocol.

If programming by radio frequency broadcast signals is to be employed, the security of the system may be improved by employing rolling codes.

Advantageously, the security device may further comprise transmitter means connected to the microprocessor and operable to transmit a verification signal for reception by a remote receiver, and the microprocessor may be arranged to be programmable by means of broadcast signals only after a verification procedure is satisfied, verifying that the broadcast signals received by the receiver means have been correctly encoded in accordance with the verification signal.

This means that the device can only be programmed by a programming unit incorporating or connected to the remote transmitter and remote receiver, where the programming unit "knows" (ie. is itself programmed with) the correct "handshake" protocol, or is arranged to automatically encode the broadcast signal in the correct way. Thus the security device may only be programmed by means of a two-way interaction between the microprocessor and a remote programming unit, the interaction involving the broadcast signals received by the receiver means and the verification signal received by the remote receiver. This arrangement further inhibits unauthorised tampering or reprogramming of the security device.

Advantageously, the verification signal may be a low power, short range signal, so that the device may only be programmed by means of a suitable programming unit in the immediate vicinity of the device, ie, within range of the verification signal. The "short range" may preferably be less than lm, and even more preferably be less than 50cm. Other ranges may of course be used, determined largely by the power of the transmitter means, but in general, the shorter the range the more secure the programming, as it makes the programming signals more difficult to intercept or capture to determine the programming protocol.

The transmitter means may transmit the verification signal in a narrow beam, and the verification signal may, advantageously, be in the optical frequency range, or in the infrared frequency range.

The transmitter means may comprise an infrared LED.

According to a second aspect of the second invention there is provided electrical and/or electronic apparatus in combination with a security device.

According to a third aspect of the present invention there is provided a security device in combination with programming means, wherein the programming means comprises the remote transmitter and is operable to transmit the broadcast signals for programming the microprocessor of the security device.

Advantageously, the remote transmitter may be arranged to operate at a low power to restrict the broadcast signals to short range. Preferably, this short range may be less than lm, and more preferably may be less than 20cm. Other ranges may of course be employed, but in general the shorter the range the more secure the programming link. Short range programming makes interception, "grabbing", or "eavesdropping" on the programming signal more difficult for an unauthorised person.

The remote transmitter may be arranged to transmit the broadcast signal in a narrow beam. The angular beam width may preferably be less than 300, and even more preferably may be less than 20 . Other beam widths may be employed, but again, in general the narrower the beam width the greater the inhibition of unauthorised interception of programming transactions.

The remote transmitter may be operable to transmit broadcast signals in a wide frequency range, but preferably the broadcast signals are in the optical or infrared ranges. The remote transmitter may comprise an infrared LED.

The programming means may also comprise a remote receiver for receiving verification signals from the security device, and may be operable to program the microprocessor only by a process involving a two-way "handshake" between the microprocessor and the programming means involving the broadcast signals and the verification signals.

According to a fourth aspect of the present invention there is provided a security system for inhibiting unauthorised tampering with a plurality of pieces of electrical and/or electronic apparatus, the system comprising a plurality of security devices, each one associated with, or attached to, a respective piece of apparatus. The system may advantageously comprise a control unit, able to identify the origin of received alarm signals from encoded identification data. The control unit may be programmable, for example to log alarm signals received, to ignore signals from certain devices during defined times of the day, for example, while an engineer is working on the device, or in a wide variety of alternative configurations.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig.1 is a schematic diagram of an in-line security device in accordance with a first embodiment of the present invention, attached to a piece of electrical apparatus; Fig. 2 is a schematic diagram of a security device in accordance with a second embodiment; Fig. 3 is a schematic diagram of a third embodiment; Fig. 4 is a schematic diagram of a security device and part of a programming unit in accordance with a fourth embodiment; Fig. 5 is a schematic diagram of a security device and programming unit in accordance with a fifth embodiment; Fig. 6 is a schematic diagram of a sixth embodiment; Fig. 7 is a schematic diagram of a seventh embodiment; Fig. 8 is a perspective view of a security device in accordance with an eighth embodiment, adapted for mounting in an expansion port of a computer or peripheral device; Fig. 9 is a schematic diagram of a security device and programming means in accordance with a ninth embodiment; Fig. 10 is a diagram of the circuit of a security device in accordance with a tenth embodiment of the present invention; Fig. 11 is a diagram of the circuit of a security device in accordance with an eleventh embodiment; Fig. 12 is a schematic diagram of a security device in accordance with the eleventh embodiment, along with its programming unit.

Referring now to Fig. 1 in a first embodiment of the present invention, the security device 50 is attached to the outside of the piece of electrical apparatus 40 by means not shown in the figure. A receiver 52 is mounted on an exposed portion of the casing of the security device 50 to receive broadcast signals from a remote transmitter 70. In this embodiment, the security device 50 is mounted in-line with the external power supply to the apparatus 40. A lead 61 connects the security device 50 to the mains supply 60, and power is supplied to the apparatus 40 from the mains 60 via the security device 50 through lead 62. Although not shown in the figure,the security device 50 comprises a vibration detector, able to detect tampering with the apparatus 40 or the security device 50, and a microprocessor. In response to an indication from the vibration detector that movement has been sensed, the microprocessor can initiate an alarm in the form of an audible signal or a radio signal transmitted to a remote sensor.

Thus, in this first embodiment, the receiver 52 is mounted on an exposed portion of the casing, so that to program or reprogram the microprocessor, the casing need not be opened or the device unattached from the protected apparatus 40. In alternative embodiments, the receiver 52 may be mounted on the "underside" of the device 50 (i.e. the side to be attached to the apparatus). The device may therefore be programmed conveniently by broadcast signals before attachment to the apparatus, and provides the further advantage that, after attachment, the receiver 52 is no longer accessible, greatly inhibiting tampering.

Fig. 2 shows an embodiment of the present invention where the receiver means 52 is located at the bottom of a cup or recess 55 in the casing of the security device 50. This restricts the number of position from which broadcast signals may be received.

Only if the remote transmitter 70 is within the angle i, determined by the geometry of the receiver 52 and the recess 55, will its signal be receivable by the receiver 52. In other embodiments, the depth of the recess may be varied to alter the "field of view", 6, of the receiver 52. Also, a window or cover may be provided, sealing the recess, the window being formed from a material which is transparent to the broadcast signals from the remote transmitter. If the transmitter 70 is in position A, outside the angle 3, then broadcast signals will not be able to programme the security device.

Fig. 3 shows an embodiment employing an alternative arrangement to restrict the number of positions of the transmitter 70 from which the receiver 52 may receive broadcast signals. The receiver 52 is mounted at the outer edge of the security device 50, but screening means 59 are provided.

Fig. 4 shows a security device 50 and part of a programming unit 80 comprising a remote transmitter 70, where the security device 50 and programming unit 80 are co-operatively adapted to inhibit unauthorised transmission of signals to the receiver 52. The receiver 52 is mounted at the bottom of an L-shaped recess 55 in the casing which is adapted to receive part of the programming unit 80 on which the remote transmitter 70 is mounted. Only when the programming unit is fully inserted into the recess (see Fig. 4(b)) is the transmitter 70 brought into direct line of sight with the receiver means 52, enabling the microprocessor to be programmed by means of broadcast signals from the transmitter 70. There is no direct line of sight from the receiver 52 to positions outside the recess 55, and unauthorised programming is significantly inhibited.

Fig. 5 shows an alternative arrangement where the receiver means 52 is mounted at the bottom of a recess 55, the entrance to which is normally closed by a flap 190 resiliently mounted to the casing of the device.

In order to programme the device it is necessary to insert the appropriately adapted programming unit 80 into the recess 55, pushing the flap to one side to allow broadcast signals to reach the receiver means 52. Such an arrangement, as well as shielding the receiver means from unauthorised signals from large distances away, also makes it difficult for any wouldbe tamperer to intercept programming signals and so gain information on the programming protocol.

Referring now to Figure 6, in a further embodiment the security device 50 is adapted to be mounted inside the casing of a piece of electrical apparatus 40. The apparatus 40 comprises a transformer 41, whose primary windings are connected to a mains supply 60. While the apparatus 40 is connected to the mains 60, the security device 50 is supplied with electrical power from the external source (the mains 60) via the transformer 41 and an internal link 150.

In the alternative arrangement shown in Figure 7, the protected apparatus 40 and the security device 50 are independently supplied with electrical power from the mains 60 via respective mains leads.

Figure 8 shows a security device 50 in accordance with an embodiment of the present invention for inhibiting unauthorised tampering with a computer or peripheral device. The device comprises a housing 54 for containing the electrical and electronic circuitry of the device, and a mounting plate 94 allowing the device to be mounted in an expansion port of the computer or peripheral to be protected. Tamper sensing means comprises a resilient electrical conductor 96 attached to the housing 54 so that one send 96a of the conductor will come into contact with the inside metal casing of the computer or peripheral when the device 50 is mounted in position as defined by the mounting plate 94 in the expansion port. The device 50 comprises transmission means including an aerial 90, for transmitting an alarm signal for reception by a remote sensor in the event of the electrical contact of the resilient conductor 96 to the metal casing being broken (eg. when t transmitting verification signals to a remote receiver 71 as part of a programming "handshake" protocol/procedure. The receiver 52 can receive signals from a wide range of angles, but in contrast, the transmitter 53 emits only a narrow beam, of width which may for example be in the region of 150. In addition, the transmitter 53 is low power, and the range of the emitted verification signal is only a distance X, where X is less than 50cm. The programming unit 80 comprises a remote transmitter 70 which is operable to emit a beam of broadcast signals of width b1 which is narrow, and a remote receiver 71 which, like the security device's receiver 52, can also receive signals from a wide range of angles.

The security device and programming unit are arranged such that before the microprocessor in the security device can be programmed, "handshake" between the security device and programming unit is required, involving two way communication. The only way that this can be achieved is if the programming unit is correctly orientated with respect to the security device (ie. with the remote transmitter 70 and remote receiver 71 pointing substantially towards the receiver means 52 and transmitter means 53 of the security device) with the receiver means 52 of the security device within the angular scope of the beam from the programming unit remote transmitter 70, and the remote receiver 71 of the programming unit within the angular scope and also within range of the beam from the security device transmitter means 53. Thus, in Figure 9, the separation of the security device and the programming unit is too great for the security device to be remotely programmed. By necessitating a very short "link" between the security device and programming unit to program the microprocessor, the security of the programming is improved.

Figure 10 shows a circuit diagram of a security device in accordance with a further embodiment of the present invention.

This security device is intended for the protection of computer peripherals and office equipment. It is intended to be attached to the outside of these pieces of equipment and has two sensors: a vibration switch; and a tamper switch to test for unauthorised removal from the protected equipment.

The device may be connected to the mains by its own mains lead, and is intended to be connected inline with the power supply to the protected equipment.

The device may resemble the embodiment shown in Fig.1.

There are two main modes of operation of the device: Mode A. Power is applied via the AC Power lead.

Mode B. The device operates on its own internal rechargeable battery.

Mode A The unit is powered from the AC supply to the protected equipment. A transformer T and bridge rectifier circuit supplies IC10, the 12V regulator.

LED3 illuminates to show power is applied. The 12V output is fed via D1 and D4 to voltage regulators IC1 & IC2. TR1 with associated components D2, D3, R2, C4 & D5 provide a constant current to trickle charge 9V nicad BT1.

There are two micro power voltage regulators IC1 (3V) & IC2 (5V).

With 12V present, IC6 is rebooted via TR3 and C21. TR3 collector keeps port A4 of the microprocessor, IC6, low whilst external power is applied. This ensures that when IC6 reboots port A4 is sampled and if port A4 is a low then the unit must be in external power (daytime) mode. This can be transmitted back to the receiver decoder to log the turning off and on of each individual unit.

Thus, TR3 and associated circuitry acts as a means for indicating to the microprocessor the state of the power supply to the device, ie. whether power is being supplied from an external source or whether the device is running off its own internal battery. In this particular embodiment, the microprocessor is programmed to ignore the vibration detection means (switch VB1) while external power is being applied (ie. while port A4 is low).

With the external 12V applied, TR8 is turned on, enabling the infra-red receiver, IC9. The coding and options of the unit are programmed via the infra-red link, (IC9 & TR4/LED2) with suitable software. The programming feature is only accessible when external power is applied.

If unauthorised removal of the device from the protected apparatus is sensed, SW1 (the case contact) will be opened, and a high will be present on port RB4 of IC6. This will force IC6 to enable the code memory in IC7, read the individual I D, turn on TR2 via port A3 and send the code data via port RB3 where it will be transmitted by IC8. Simultaneously, LED1 will illuminate for the duration of the transmission and BZ1 will be activated generating an alert tone.

Mode B When the computer is switched off the 12V will not be present. The unit will revert to running off the standby battery BT1 via D6. TR8 will turn off, disabling IC9 (the infra-red receiver) reducing the current consumption considerably. Simultaneously, TR3 will b turned off and port A4, IC 6 goes high. The high on port A4 of IC6 is sensed under software control and places IC6 in sleep mode, thereby reducing current consumption.

Ports RB4 to RB7 have the capability to interrupt on change of state.

If the unit is moved, the vibration switch VB1 makes contact and changes the state on port RB5 to a low condition. IC6 senses the change of state and is woken from the sleep condition and the units'; I D read from IC7. TR2 is turned on, data output via RB3 and IC8 transmits the movement signal to the receiver decoder.

If the unit is removed from the protected equipment SW1 goes open circuit, R15 pulls port RB4 to a high condition. IC6 senses the change of state and is woken from the sleep condition and the units' I D read from IC7. TR2 is turned on, data output via RB3 and IC8 transmits the case tamper signal to the receiver decoder.

When a low battery condition is sensed, IC3 being the low battery detector, port RB6 of IC6 is taken high. This change of state is sensed, IC6 is woken from the sleep condition and the units' I D read from IC7. TR2 is turned on, data output via RB3 and IC8 transmits the low battery signal to the receiver decoder.

After any movement, unauthorised removal or low battery condition the processor IC6 will encode the relevant data and then return to a low current consumption sleep condition.

Every 2.5 seconds IC6 is awoken from the sleep condition and LED1 flashed briefly. IC6 then resumes sleep for another 2.5 seconds and the process is repeated. This gives the user a visual indication that the unit is operative.

Figure 11 shows the circuit diagram of a similar security device intended for the protection of computer equipment. This time however, the device is arranged to receive external power from the device it is protecting (the computer) and is adapted to be mounted in an expansion port.

Again, the device has two sensors: a vibration switch VB1; and a contact assembly SW1 to test for computer case removal.

There are two main modes of operation of the device: Mode A: Power is applied via the computer's internal power unit; and Mode B: The device operates on it's own internal rechargeable battery.

In Mode A: 12V is supplied by the computer power supply through F1 & Dl. L1, L2, C1, C2 & C3 filter noise from the computer power supply. ZD1 protects against surges and power spikes above 16V.

TR1 with associated components D2, D3, R2, C4 & D5 provide a constant current to trickle charge 9V nicad BT1.

The operation of the circuit is essentially the same as that of the circuit shown in fig.10. SW1 is now arranged so that it is opened in response to computer case tamper (i.e. partial or complete removal of the case), sending port RB4 of IC6 high.

In mode B: Again the operation of the circuit is substantially the same as that of fig. 10. R15 pulls port RB4 to a high condition if the computer case tamper contact goes open circuit.

After any movement, case tamper, or low battery condition IC6 will encode the relevant data and then return to a low current consumption sleep condition.

In an earlier version of the above device (i.e. a version not in accordance with the present invention) it was necessary to disassemble the unit and set DIP switches for the unit I.D. as well as the option bits before the device was fitted to the protected equipment. This was time consuming and relatively inflexible.

The new device, embodying the present invention, overcomes these limitations by being fully programmable through an infrared interface. The range that the infrared link will operate over is limited to approximately 100mm and has a narrow beam angle of 15 degrees. The device can only be programmed when external power is applied. i.e. the computer is switched on. This ensures a very high degree of immunity against unauthorised tampering.

A software package and interface module is required to communicate with the device.

To reiterate: There are two basic modes of operation of the device: Mode A: When external power is applied; and Mode B: When the unit is operational on its standby nicad battery.

In Mode 1 (which may generally be referred to as daytime mode), when the external 12V is applied (as supplied by the computer power supply), TR3 is turned on. This forces a low pulse to be applied to the MCLR pin of IC6 (pin 4), restarting the processor. When the processor restarts, pin 3 (IC6) is sampled, and if it is a low the processor restarts in "daytime" mode.

Simultaneously, TR8 is turned off, enabling the infrared receiver IC9. The unit can be interrogated or programmed as required.

In Mode 2 (which may generally be referred to as Nighttime mode), when external power is removed (the computer turned off) pin 3 of IC6 is pulled high by R28. This change of state is sensed by the processor, IC6, which then reverts into a micro power configuration to conserve battery power.

Simultaneously, TR8 is turned off, disabling the infrared receiver IC9. With IC9 turned off it is impossible to communicate with the device as the infrared link is inoperative.

Dos programmer operation A software package and interface has been developed to communicate with the device. The interface module plugs into the RS232 port of the PC running the programming utility. See fig. 12.

To interrogate the device 50 the user must ensure that the interface module 80 is aligned with the infrared emitter 53 and receiver 52 on the device's mounting plate 94. It will not be possible to read or program the unit if the distance is greater than 100mm or the infrared receiver/emitters are not in alignment. The beam width tolerance has been deliberately chosen to be narrow at typically 15 degrees.

On the PC being used to run the software, the R key is pushed to display the unit's current I.D. If the link is out of alignment a message will be displayed "Failed last read attempt".

If the I.D. is to be changed, the I key is pressed and a new four digit code entered. If the link is out of alignment a message will be displayed "Failed last write attempt".

The infrared programming interface is protected against unauthorised tampering. If more than three incorrect access verifications are attempted the device will transmit an IRLINK tamper back to the receiver decoder panel (i.e. the control unit monitoring the security system, and comprising a remote sensor for receiving alarm signals).

Features of the Device The above described device, by incorporating a microprocesser may therefore be programmed in a wide variety of configurations. Options include: Fixed serial number and firmware version.

Although the device may be programmed with an address, and transmit data indicative of that address when tamper is detected, it may also have a fixed ie.

non-programmable serial number embedded in its circuitry to enable individual security devices to be uniquely identified at a later date after leaving the factory.

Proarammable unit I.D.

The security device may be programmed with identification data which it transmits with the alarm signal to identify the device being tampered with.

Proarammable confidence LED on/off.

When the tamper sensing means is enabled, the device may be arranged to display a flashing LED to inform the user that the device is armed, and to deter a would-be tamperer.

Proarammable "Case tamper option.

The case tamper detection feature may be enabled or disabled according to the programming of the microprocesser.

Proarammable "Movement sensor" option.

Similarly, although the hardware may include a vibration detection switch, the microprocessor need not pay any attention to it. The movement sensor means is enabled according to the microprocessor's programming.

Proarammable sensitivitv adiustment for movement sensor.

This may be achieved, for example, by programming the microprocessor to look at the duration of the signal from the movement/vibration detector.

Proarammable "buzzer" option.

The device may be programmed to generate an audible alarm when tamper is detected (see for example the loudspeaker BZ1 in Figs. 10 and 11).

Proqrammable option configuration Various configurations may be programmed into the microprocessor (for example, corresponding to daytime mode, nighttime mode, different levels of sensitivity to different tamper sensing means,) and pre-stored configurations (ie. packages of settings) may be selected simply by inputting a code indicative of the particular configuration.

Programmable model number.

The device may have a programmable model number, or configuration bit, indicative of whether it is an in-line or an internal apparatus-powered device. This bit may only be read by the programming module, and is useful for database management. The programming unit can tell which sort of device it is communicating with.

Proarammable number of event transmissions.

The number of times the device transmits an alarm signal, and for how long, after tamper has been detected, may be programmed.

Proarammable code rate.

An option may be to program the baud rate of the encoded alarm signal.

Computer switch on/off verification.

Each time the device is switched on or off the microprocessor may be programmed to send an indicative signal to a remote sensor. A control unit connected to the sensor may therefore be able to log the turning on and off of the equipment under its watch.

Low battery verification.

The device may be programmed to send a signal to a remote sensor when the battery is low.

"Learn mode" activation.

This is a programming feature whereby one can send the device a particular code, the device then sends a signal, which is not an alarm signal, to the control panel which tells the panel to accept future alarm signals from that device, even though the control panel might previously have been unaware of the existence of that particular device. Thus, additional security devices may be introduced into an existing security system, and the system may learn to recognise these new additions without the control panel having to be "told" directly.

"Service mode" verification.

The device may be able to send an indication with the alarm signal that although a tamper has been detected, it has originated from an authorised user, who for example, has input an appropriate code.

Event/fault log interrogation.

The microprocessor may be able to keep its own log of events such as tamper sensing means activation, and the device may be interrogated in order to learn the contents of this log.

Referring once more to Figure 12, in order to program or read the device 50, it must be connected to the Programmer Module's 80 disk drive power connector or fitted in a PC with the PC's power turned on.

The device 50 and/or the Programming Module 80 should be positioned such that the device's infrared LED 53 is facing the Programming module's infrared receiver 71 and vice versa. Ideally, the tip of the devices aerial 90 should just touch the case of the programming module 80. However the distance between the two units should not exceed 100mm (4").

Whilst in the embodiments described above the security devices have been separate entities and distinguishable from the pieces of apparatus they protect, it will be apparent that in alternative embodiments the apparatus and security device may be integral. The "security device" may be built into the apparatus, for example with its components distributed amongst other components of the apparatus. In such arrangements it may be impossible to separate the "security device" from the protected apparatus as an independent entity.

Claims (43)

1. A security device for inhibiting unauthorised tampering with electrical and/or electronic apparatus, comprising: sensing means for sensing tampering with said apparatus and/or said device; receiver means for receiving broadcast signals from a remote transmitter; and a microprocessor connected to said sensing means and said receiver means, said microprocessor being operable to initiate an alarm in accordance with its programming and in response to an indication from said sensing means that tampering has been sensed, and being programmable by means of said broadcast signals.

2. A security device in accordance with claim 1, wherein said sensing means comprises vibration detection means for detecting movement of said device.

3. A security device in accordance with claim 1 or claim 2 wherein said sensing means comprises relative movement detection means arranged to detect relative movement of at least a portion of said apparatus with respect to at least a part of said device.

4. A security device in accordance with any preceding claim wherein said sensing means comprises means for detecting the opening or removal of the casing of said apparatus.

5. A security device in accordance with any preceding claim wherein said sensing means comprises means for detecting attempted separation of said device from said apparatus.

6. A security device in accordance with any preceding claim, adapted to restrict the range of positions of said remote transmitter from which said broadcast signals can be received by said receiver means.

7. A security device in accordance with any preceding claim, further comprising a portion of casing, arranged to be exposed when said security device is attached to said apparatus, wherein said receiver means is positioned in a recess in said portion of casing.

8. A security device in accordance with any preceding claim wherein said receiver means is highly directional.

9. A security device in accordance with any preceding claim, further comprising state indicating means for providing an indication of the state of said apparatus, said state indicating means being connected to said microprocessor.

10. A security device in accordance with any preceding claim further comprising a battery for supplying electrical power to operate said microprocessor.

11. A security device in accordance with any preceding claim further comprising transmission means for transmitting an alarm signal for reception at a remote sensor in response to said microprocessor initiating an alarm.

12. A security device in accordance with claim 11 further comprising memory means for storing identification data, and encoding means for encoding said alarm signal according to said identification data to enable said remote sensor to identify the security device from which said alarm signal is being sent.

13. A security device in accordance with claim 12 wherein said memory means is programmable by means of said broadcast signals.

14. A security device in accordance with any preceding claim, further comprising means for connecting the device to an external supply of electrical power.

15. A security device in accordance with any preceding claim wherein said device comprises means for connecting said device to said apparatus to receive electrical power from said apparatus.

16. A security device in accordance with any one of claims 1 to 14 further comprising means for connecting said device to said apparatus to supply electrical power to said apparatus.

17. A security device in accordance with any one of claims 14 to 16, further comprising monitoring means connected to said microprocessor and operable to provide a monitoring signal indicative of whether power is being supplied to said security device from said external supply or not.

18. A security device in accordance with any one of claims 14 to 17, wherein said microprocessor is programmable by means of said broadcast signals only whilst said device is connected to said external supply of electrical power.

19. A security device in accordance with any one of claims 14 to 18 wherein said receiver means is disabled while said device is not connected to said external supply.

20. A security device in accordance with any preceding claim, further comprising mounting means for mounting the security device to said apparatus.

21. A security device in accordance with any preceding claim further comprising mounting means for mounting the security device in an expansion port of a computer or an associated peripheral device.

22. A security device in accordance with any preceding claim wherein said broadcast signals are optical signals substantially in the frequency range 1014 to 1015 Hz and said receiver means comprises an optical receiver.

23. A security device in accordance with any one of claims 1 to 22 wherein said broadcast signals are infrared signals substantially in the frequency range 1011 to 1014 Hz and said receiver means comprises an infrared receiver.

24. A security device in accordance with any preceding claim further comprising transmitter means, connected to said microprocessor, for transmitting a verification signal for reception at a remote receiver, said microprocessor arranged to be programmable by means of said broadcast signals only if said broadcast signals are correctly encoded in accordance with said verification signal.

25. A security device in accordance with any preceding claim further comprising transmitter means connected to said microprocessor, for transmitting a verification signal for reception by a remote receiver, wherein said microprocessor is programmable only after a "handshake" with a programming unit comprising said remote transmitter and said remote receiver, said "handshake" involving said broadcast signals and said verification signals.

26. A security device in accordance with claim 24 or claim 25 wherein said transmitter means is arranged to transmit said verification signal over only a short range, said short range being less than lm.

27. A security device in accordance with any one of claims 24 to 26 wherein said transmitter means is arranged to transmit said verification signal in a narrow beam of width less than 30 .

28. A security device in accordance with any one of claims 24 to 27 wherein said verification signal is in the optical frequency range 1014 to 1015 Hz.

29. A security device in accordance with any one of claims 24 to 27 wherein said verification signal is in the infrared frequency range 1011 to 1014 Hz.

30. A security device in accordance with claim 29 wherein said transmitter means comprises an infrared LED.

31. The combination of a security device in accordance with any preceding claim with said electrical and/or electronic apparatus.

32. The combination of a security device in accordance with any one of claims 1 to 30 with programming means, wherein said programming means comprises said remote transmitter and is operable to transmit said broadcast signals for programming said microprocessor.

33. A combination in accordance with claim 32 wherein said programming means and said security device are co-operatively adapted to inhibit unauthorised transmission of signals to said receiver means.

34. A combination in accordance with claim 32 or 33 wherein said remote transmitter is arranged to transmit said broadcast signals over a range of less than lm.

35. A combination in accordance with any one of claim 32 to 34 wherein said remote transmitter is operable to emit said broadcast signals in a narrow beam of width less than 300.

36. A combination in accordance with any one of claims 32 to 35 as dependent from claim 24, wherein said programming means further comprises said remote receiver, and is operable to encode said broadcast signals according to said verification signals received by said remote receiver.

37. A combination in accordance with any one of claims 32 to 36, as dependent from claim 25 wherein said programming unit comprises said remote receiver and is operable to program said microprocessor by means of a two way interaction with said microprocessor involving said broadcast signals and said verification signals.

38. A security device substantially as hereinbefore described with reference to the accompanying drawings.

39. The combination of a security device with electrical and/or electronic apparatus substantially as hereinbefore described with reference to the accompanying drawings.

40. The combination of a security device with programming means substantially as hereinbefore described with reference to the accompanying drawings.

41. A security system for inhibiting unauthorised tampering with a plurality of pieces of electrical and/or electronic apparatus, the system comprising: a plurality of security devices in accordance with claim 11, or any one of claims 12 to 30 as dependent from claim 11, each said security device being associated with a respective piece of said apparatus; and at least one remote sensor for receiving said alarm signals.

42. A security system for inhibiting unauthorised tampering with the plurality of pieces of electrical and/or electronic apparatus, the security system comprising: a plurality of security devices in accordance with claim 12, or any one of claims 13 to 30 as dependent from claim 12, each said security device being associated with a respective piece of said apparatus; at least one remote sensor for receiving said alarm signals; and a control unit operable to identify the security device emitting an alarm signal from the received alarm signal.

43. A security system substantially as hereinbefore described with reference to the accompanying drawings.