Patent Description:
An anti-intrusion security system in accordance with <CIT> comprises fog-generating devices which impairs the sight of an intruder when activated. The devices for generating the fog comprise a heat exchanger for heating and vaporising the fluid with a resistor embedded on a body. When an intruder detection system is activated, an appropriate signal is sent to an anti-intrusion security system that initiates delivery of fog.

<CIT> discloses a fog-generating device comprising a power source and a reservoir containing fog-generating liquid. An external surveillance system may send an alarm signal to the fog-generating device, upon which a switch is controlled in the fog-generating device which closes a circuit containing the ignition energy source (e.g. a capacitor or supercapacitor) and the ignition means, thereby igniting the reagent. The documents <CIT> and <CIT> describe intrusion detection systems with a smoke generation device.

When the appropriate signal is sent to the smoke generator and the smoke generating process has been initiated it is not possible to interrupt or stop the process. Therefore, it is desirable to improve the safety arrangements around the initiating process, so as to reduce the risk for unintentional activation of the smoke generator.

In accordance with the invention there is provided a device for controlling and powering a smoke generator as defined in claim <NUM>. terrThere is a special concern about the possibility of having an accidental activation of the smoke generator. Once the smoke generation is activated, the pyrotechnic nature of the product disables the possibility of stopping the smoke generation.

In various embodiments the device is a peripheral comprising a safety circuit and the smoke generator. The smoke generator comprises a smoke generator component, referred to as a canister. The device will generate smoke in the premises after a burglary or danger situation is verified, for instance from a remote monitoring station. For this purpose, the new device can be integrated in presently available alarm systems as any other peripheral, communicating with at least one control unit, also referred to as a gateway, via a radio frequency, RF, interface.

In various embodiments the device is designed to guarantee a reliable activation during the full life cycle of the device. The device in accordance with the invention will have a very quick and secure action. Emission of smoke starts within seconds of activation and will last at least one minute. The opacity of the smoke is very high.

In order that the manner in which the above recited and other advantages and objects of the invention are obtained will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.

In <FIG> an alarm system is arranged in premises in the form of a building <NUM>. The alarm system comprises at least one control unit <NUM> also referred to as a gateway that, for example, includes a processor and an alarm unit for providing an alarm signal when the alarm is set off.

The alarm system comprises at least one and preferably a plurality of premises perimeter detectors <NUM>, such as a first premises perimeter detector 14a and a second premises perimeter detector 14b. The premises perimeter detectors <NUM> are, for example, detectors sensitive to the presence or passage of persons and objects. For example, presence detectors include motion detectors, such as IR-detectors, and passage detectors include magnetic sensors arranged at windows <NUM> and doors, such as an entrance door <NUM>. Other detectors with similar properties can also be included. The alarm system further comprises at least one and preferably a plurality of premises interior detectors <NUM>, such as a first premises interior detector 20a and a second premises interior detector 20b. The interior detectors may include IR-sensors.

The control unit <NUM> is connected to the premises perimeter detectors <NUM>, the premises interior detectors <NUM> and to input means <NUM>, such as a keypad or similar, for arming and disarming the detectors <NUM>, <NUM> to arm and disarm the alarm system. For example, the control unit <NUM> is activated and controlled by the input means <NUM>. Alternatively, the control unit <NUM> is provided with the input means <NUM>. Alternatively, the input means <NUM> is a remote device, such as a wireless remote device. In the illustrated embodiment, the input means <NUM> is arranged in the vicinity of the entrance door <NUM>. Alternatively, the input means <NUM> is arranged in any suitable location or is a portable device, such as a cell phone. The detectors <NUM>, <NUM> are, for example, provided with wireless communication means for communicating with the control unit <NUM>.

In the embodiment of <FIG> the control unit <NUM> is connected to an alarm receiving centre <NUM>, such as a remote alarm receiving centre, either by wire, such as a telephone line as indicated in <FIG> with a dashed line, or by a wireless telecommunications system such as GSM or other radio frequency systems. The connection also can be through the internet <NUM>. For example, the control unit <NUM> is provided with communication means for communicating with the remote alarm receiving centre <NUM>. Alternatively, the alarm receiving centre <NUM> is located within the premises or within the building <NUM>. In the embodiment shown in <FIG> the remote alarm receiving centre <NUM> comprises a web server <NUM>, a control and communications unit <NUM> and a database <NUM>. The web server <NUM> is an interface for a user to set up and to monitor the alarm system of the building <NUM>. Different settings and information regarding the alarm system and different users of the alarm system are stored in the database <NUM>. Communication between the user, the alarm system and the remote alarm receiving centre <NUM> is processed through the control and communications unit <NUM>.

According to one embodiment at least one premises interior detector <NUM> comprises or is connected to an image capturing means, such as a camera, video camera or any other type of image capturing means, wherein the image capturing means is activated when said detector <NUM> is triggered. For example, at least one premises interior detector <NUM> comprises an image capturing means, which image capturing means is activated by the triggering of the interior detector <NUM> connected to it, so that the image capturing means is switched on when the interior detector <NUM> detects an unauthorized intrusion.

In the building <NUM> there is provided also a smoke generator <NUM> capable of producing and distributing an opaque smoke after being initiated and activated by the alarm system, preferably through the control unit <NUM>. The smoke generator <NUM> can be arranged on a wall by a wall attachment or be designed to be placed on a table or shelf. After being activated the smoke generator <NUM> will emit smoke that eventually will fill the premises in the building.

According to the invention, the smoke generator <NUM> shown in <FIG> comprises a smoke generator component, referred to as a canister <NUM>. The canister is a chemical pyrotechnic component which is available for instance from French company ALSETECH. The smoke generated is completely non-toxic and contains only very small amounts of CO and CO<NUM>.

In various embodiments the smoke generator <NUM> is a stand-alone or self-contained unit where a battery or a set of batteries form a power supply unit <NUM>. Communication between the smoke generator <NUM> and other peripheral units of the alarm system and specifically the control unit <NUM> is handled by a communication unit <NUM>. The smoke generator <NUM> is controlled by a central unit <NUM>, comprising a processor and memory units. The central unit <NUM> will communicate with the control unit <NUM> of the alarm system when an alarm situation occurs and activation of the smoke generator <NUM> is desired. Control signals from the central unit <NUM> are forwarded to a driver circuit <NUM> that is connected to the canister <NUM>.

An embodiment of the driver circuit <NUM> of the smoke generator <NUM> as shown in <FIG> comprises a charging unit <NUM>, a switching unit <NUM> and a connecting unit <NUM>. The charging unit <NUM> comprises charging means, such as capacitors or similar components capable of storing electric energy, and electronic circuits for controlling supply of current from the power supply unit <NUM> to the charging means, c. The charging unit <NUM> is connected to the central unit <NUM> and will receive a Charge signal when a smoke generator activating signal has been received by the central unit <NUM>. The charging process of the charging means will take some time before an appropriate amount of energy has been obtained. In various embodiments a fixed time period is assigned for the charging process. In other embodiments the actual charged amount is measured by the central unit. No activation of the canister is possible during the charging process. A timing process for enabling and activating the smoke generator <NUM> is further explained below with reference to <FIG>.

The canister <NUM> is connected to the connecting unit <NUM> which needs to enter a closing condition to allow the canister <NUM> to be activated properly. The closing condition is entered when a Connect signal is received from the driver circuit <NUM>. The switching unit <NUM> is connected to the charging unit <NUM> and to the canister <NUM>. In a final step for activating the canister <NUM> the switching unit <NUM> receives a trigger signal from the central unit <NUM>. The switching unit <NUM> then switches on and energy stored in the charging unit <NUM> can be passed on to the canister <NUM> on the condition that the connecting unit <NUM> has entered the closing condition.

The driver circuit <NUM> further comprises a testing unit <NUM> which is connected to the canister <NUM>. The testing unit <NUM> has an input Test and an output Vtest. By applying a signal at input Test it is possible to detect presence of the canister <NUM> and also to detect information relating to the physical status of the canister <NUM>. These data can be used to detect tampering attempts and when exchange of the canister is due.

In the embodiment of a driver circuit <NUM> shown in <FIG> the charging unit <NUM> comprises a first active component <NUM>. In the selected arrangement of power voltage, grounding of circuits and canister the first active component <NUM> is a P-channel enhancement mode MOSFET, such as one available from DIODES INCORPORATED as DMP2305U. In other arrangements, for instance with opposite polarities of power supply, other suitable components can be used still providing the same function. The charging unit <NUM> further comprises charging means <NUM>. A suitable implementation of the charging means <NUM> is at least one, or as shown in <FIG> two, capacitors with a total capacity of <NUM>µF. The charging unit <NUM> comprises a restricting resistor RD that will limit charging current from power supply VCC to the charging means <NUM>.

The switching unit <NUM> comprises in the shown embodiment a second active component <NUM>. In the selected arrangement of power voltage, grounding of circuits and canister the second active component <NUM> is a P-channel trench MOSFET, such as one available from NXP SEMICONDUCTORS as PMV27UPE. In other arrangements, for instance with opposite polarities of power supply, other suitable components can be used still providing the same function. An activation signal at input Trigger will connect a first pole <NUM> of the canister <NUM> to the charging means <NUM>. Restricting resistor RD will limit current also in a situation where an activation signal at input Trigger is given in error during a time period where also a signal is provided at Charge input.

The connecting unit <NUM> comprises in the shown embodiment a third active component <NUM>. In the selected arrangement of power voltage, grounding of circuits and canister the third active component <NUM> is an N-channel trench MOSFET, such as one available from NXP SEMICONDUCTORS as PMV30UN2. In other arrangements, for instance with opposite polarities of power supply, other suitable components can be used still providing the same function. A pre-activation signal at input Connect will connect a second pole <NUM> of the canister <NUM> to ground (GND). A current limiting resistor RL, which is always connected between the second pole of the canister <NUM> and ground (GND) will limit the current through the canister below a level where the canister in is activated. In the shown embodiment RL is <NUM> Ohm.

The testing unit <NUM> comprises a fourth active component <NUM>. In the selected arrangement of power voltage, grounding of circuits and canister the fourth active component <NUM> is a P-channel enhancement mode MOSFET, such as one available from DIODES INCORPORATED as DMP2305U. In other arrangements, for instance with opposite polarities of power supply, other suitable components can be used still providing the same function. By applying a test signal at the Test input fourth active component <NUM> will enter an ON state and current will be allowed to flow through a limiting resistor RT to the canister <NUM>. The limiting resistor RT, normally at about <NUM> Ohm, will ensure that the current to the canister <NUM> will be limited to a value below the value required for activation. In the shown embodiment, the current to the canister will be limited to a maximum value of <NUM> mA, even if the connecting unit <NUM> accidently is activated when the testing unit is activated. The current that actually flows through the canister when the test signal is applied will indicate presence of the canister <NUM> and also to some extent the status of content of the canister. A test output signal, Vtest, can be obtained at the fourth active component <NUM>.

In a default mode all active components are in the OFF state. In this mode first pole <NUM> of canister <NUM> is connected to ground through shorting resistor RS and current limiting resistor RL. Second pole <NUM> of canister <NUM> is connected to ground through current limiting resistor RL. In the embodiment shown in <FIG> RS is <NUM> Ohm. As a result, the smoke generator cannot be activated in this mode.

Normal steps for activating the smoke generator to provide smoke include provision of input signal at input Charge. This input signal and also other signals indicated in <FIG> and <FIG> are provided by central unit <NUM> on the basis of signals received from the control unit <NUM> indicating an alarm situation. Below the term HIGH implies supply voltage VCC or a voltage level close to that. Correspondingly, the term LOW implies ground GND or a voltage level close to that. An ON state of all active components corresponds to a closed switch condition, that is a condition where a maximum current flows through the component. An OFF state of all active components corresponds to an open switch condition, that is a condition where practically no current flows through the component. Signals at HIGH level are considered to be of opposite polarities as compared to signals at LOW level.

The type of semiconductor used as first active component <NUM> is put into an ON state by changing from HIGH to a LOW signal at the gate of the P-channel enhancement mode MOSFET. As a result, current will flow from power supply at VCC and start charging the charging means <NUM>. The time required for charging the charging means <NUM> to an appropriate level may vary in dependence on selected components and voltage levels. In the embodiment shown in <FIG> a normal charging time is about <NUM>. Even when charged to an appropriate level no energy is automatically transferred to the canister <NUM> because the second active component <NUM> is maintained at an OFF state in which current is prevented from passing through. Also third active component <NUM> is kept at an OFF state to further prevent activation of canister <NUM>.

First pole <NUM> of canister <NUM> is connected to "positive" units that will provide positive signals for activation of canister <NUM>. These units are charging unit <NUM> and switching unit <NUM>. Also the testing unit <NUM> is connected to first pole <NUM> of canister <NUM>. Second pole <NUM> of canister <NUM> is connected to a "negative" unit that will provide a negative (or grounding) signal. Smoke generation requires that "positive" as well as "negative" units are activated during an overlapping time period. If "positive" charging unit <NUM> or "positive" switching unit <NUM> is activated while "negative" connecting unit <NUM> is not activated the maximum current that can flow through the canister <NUM> is limited by resistor RL. The limited current cannot activate smoke generation.

In a similar manner, if "negative" connecting unit <NUM> is activated while "positive" charging unit <NUM> and "positive" switching unit <NUM> are not activated no current can be supplied from power supply because first active component <NUM> and second active component <NUM> are both in the OFF state. As a result, no smoke generation can be activated. Furthermore, "positive" units and "negative" units in the shown embodiment are controlled with opposite polarities to reduce the probability of an accidental application of control signals in smoke generator <NUM>.

Accidental activation of both control signals CHARGE and TRIGGER at the same time will not activate the smoke generation, as resistor RD will limit current to about 40mA, which is a safe value. The designed charging time of about <NUM> will allow to incorporate easily safety mechanisms in the firmware to prevent undesired activation.

Timing diagram of <FIG> shows how input signals CHARGE, TRIGGER and CONNECT interact to produce output FOG1 during normal conditions. The first step for activation of the smoke generator will be to activate input signal CHARGE by setting first active component <NUM> into ON state. This is done by applying a LOW signal. All other active components being in an OFF state current will flow through first active component <NUM> and through resistor RD to charging means <NUM>. As set out above the time required for the charging means <NUM> to an appropriate level would be about <NUM>. Thus, time period T1 in <FIG> is equal to about <NUM>. After this time period input signal CHARGE is set to HIGH to set first active component <NUM> into OFF state. As a result, charging of charging means <NUM> is stopped.

In the shown embodiment, there is a short delay and then input signal CONNECT is activated by setting it to HIGH. In this state, third active component <NUM> will be set to ON resulting in a very low resistance. In practice this means that second pole <NUM> of canister <NUM> is connected to ground GND. This is a preparation for full activation of the canister which is done by activating input signal TRIGGER. Input signal CONNECT is maintained at HIGH during at least the full length of activated input signal TRIGGER.

Activation of input signal TRIGGER is done by setting it to LOW. As a result, second active component <NUM> is set to ON which in practice connects first pole <NUM> of canister <NUM> to charging means <NUM> and will allow a current at a high level to flow into the canister <NUM>. Depending on the type of canister <NUM> the high level current can be about 1A or more. As a result, smoke is generated during a time period T2. In the embodiment described above T2 is equal to or longer than <NUM>.

Claim 1:
A driver circuit (<NUM>) for controlling and powering a smoke generating canister (<NUM>) to emit smoke, the driver circuit (<NUM>) comprising first and second terminals for respective connection to a first pole (<NUM>) and a second pole (<NUM>) of the smoke generating canister (<NUM>) for activation thereof, characterised by
a charging unit (<NUM>) configured to provide after a charging process of the charging unit (<NUM>), sufficient power to activate the smoke generating canister (<NUM>),
a switching unit (<NUM>) connected to the charging unit (<NUM>) and to the first terminal, wherein the switching unit (<NUM>), upon activation thereof, is configured to release power from the charging unit (<NUM>) to the smoke generating canister (<NUM>) via the first terminal when the smoke generating canister (<NUM>) is connected thereto, and
a connecting unit (<NUM>) connected to the second terminal and to electrical ground (GND), wherein the connecting unit (<NUM>), upon activation thereof, is configured to allow power to flow through the smoke generating canister (<NUM>) when the smoke generating canister (<NUM>) is connected between the first and second terminals,
wherein, when the smoke generating canister (<NUM>) is connected between the first and second terminals, activation of both the connecting unit (<NUM>) and the switching unit (<NUM>) during an overlapping time period is required for activation of the smoke generating canister (<NUM>).