FOREIGN PRIORITY

This application claims priority to European Patent Application No. 19213175.3, filed Dec. 3, 2019, and all the benefits accruing therefrom under 35 U.S.C. § 119, the contents of which in its entirety are herein incorporated by reference.

TECHNICAL FIELD

The present invention relates to a manual call point for a fire alarm system, and to a related method of activating a manual call point for a fire alarm system.

BACKGROUND

In many jurisdictions fire alarm systems are provided with manual call points allowing for manual fire alarm activation via human intervention. Typically some form of electromechanical device is used allowing for a person to sound an alarm, such as an evacuation alarm in a building. Often these manual call points are used in conjunction with automatic fire alarm systems in which there is a possibility for automatic activation using sensors such as heat detectors and smoke detectors. Automated fire suppression systems can be provided within the same system. The manual call points can be wired into the fire alarm system or in some cases may be wirelessly connected.

As the manual call points are an important safety feature then it is typical for regulations to set requirements for their appearance, operation and placement, as well as setting out methods of testing to ensure that call points have the required performance before they are placed on the market. For example, European Standard EN 54 part 11 specifies the requirements and methods of test for manual call points in fire detection and fire alarm systems in and around buildings. This European Standard contains provisions similar to those in other jurisdictions where manual call points are used, defining different required elements of the manual call point as well as how they should function.

Within this document the following terminology is used, which is consistent with the terminology of EN 54-11 for the sake of convenience. It will be appreciated that the terms used should apply in the same way to equivalent structural and functional elements of manual call points intended for operation in other jurisdictions, i.e. meeting alternative regulatory requirements where the terminology may differ.

As referenced herein, an alarm condition is the condition of the manual call point after an operating element thereof has been activated. The operating element is a mechanical and electrical switching element; the part of the manual call point that initiates the alarm signal when operated. Typical manual call points also include a frangible element, which is a component made of glass or having the appearance of glass (e.g. “plastic glass”) and which after receiving a blow or pressure, is physically broken or is visibly displaced by change of position and remains in that condition until replaced or reset. The frangible element gives protection against unintentional operation, i.e. by resisting relatively small forces, and is a deterrent against misuse. The breaking or apparent breaking (e.g. visible displacement) of the frangible element is designed to be necessary in order to activate the operating element, which typically includes a part visible to the user through the frangible element.

Manual call points can be provided with a non-resettable frangible element, i.e. a frangible element that needs to be replaced after the activation of the manual call point, in order for the manual call point to be able to return to a normal condition. Alternatively there may be a resettable frangible element that can be returned to its original position without replacement, in order for the manual call point to be able to return to the normal condition also without replacement of the frangible element. The normal condition is a condition in which the frangible element is undamaged and the manual call point is operating without giving an alarm or fault signal.

Manual call points are divided into two types depending on the method of operation, with EN 54-11 denoting these as type A: direct operation, and type B: indirect operation. A direct operation manual call point is a device in which the change to the alarm condition is automatic (i.e. without the need for further manual action) when the frangible element is broken or displaced. An indirect operation manual call point is a device in which the change to the alarm condition requires a separate manual operation of the operating element by the user after the frangible element is broken or displaced, e.g. where breaking the frangible element gives access to the operating element.

As noted above, the alarm condition is the condition after activation of the operating element. Typically the transfer from the normal condition to the alarm condition is easily recognisable by the change in the appearance of the operating face, such as by the breakage or apparent breakage of the frangible element and/or by movement of the operating element. For indirectly operated call points it is also required by EN 54-11 that in the alarm condition it shall be possible to see that the operating element is in the activated position and it shall not be possible to activate the operating element without breaking or displacing the frangible element (unless with the use of a special tool, e.g. a key used for testing the device).

In existing manual call points the operating element is often an electromechanical switch device such as a micro-switch or other switch device in which physical movement of the operating element brings electrical contacts into or out of engagement.

SUMMARY

Viewed from a first aspect, the present invention provides a manual call point for a fire alarm system, the manual call point comprising: an operating element, wherein a physical movement of the operating element will trigger an alarm condition of the manual call point; and at least two switch devices, with each switch device being for completing or breaking a circuit in response to the physical movement of the operating element; wherein at least one of the switch devices is a contactless device and the corresponding circuit includes an electromagnetic circuit that is completed or broken without mechanical contact from the operating element.

With this manual call point advantages are provided in relation to increased reliability and a reduced requirement for testing of the operation of the call point. The use of a contactless switch using an electromagnetic circuit avoids many failure modes that affect prior art designs relying solely on an electromechanical switch, such as corrosion of the electrical contacts. The contactless switch can be arranged to be normally open or normally closed, with the state of the switch changing in response to activation of the operating element, i.e. in response to the physical movement thereof (but without mechanical contact). Moreover, as discussed in more detail below, a contactless switch can allow for the possibility of self-verification, whereby the call point can confirm the continued operation of the electromagnetic circuit without the need for manual triggering of the operating element to test the functioning of the call point. The activation of the alarm condition of the call point may rely on any one switch changing state, thereby increasing reliability by providing redundancy in the event of a failure of a switch. Also, if an activation of the alarm condition is triggered with fewer than all of the switches changing state then this can be used as an alert indicating a possible failure, so that the manual call point can be inspected and, if needed, repaired or replaced.

In some implementations, the at least two switch elements include the contactless switch and an electromechanical switch. The electromechanical switch may include a micro-switch, for example. In that case the call point will include one electromagnetic circuit with a switch that completes or breaks the circuit without mechanical contact with the operation element and one electromechanical switch that completes or breaks an electrical circuit via mechanical contact with the operating element, such as via forces from the operating element on a physical contact mechanism of the electromechanical switch. This means that the call point has redundancy via two different forms of switch device having quite different failure modes, which increases reliability. Failure modes relating to degradation or interference that have a significant risk to the electromechanical switch, such as corrosion from moisture, are not likely to generate the same level of risk to the electromagnetic switch. Similarly, failure modes relating to degradation or interference that have a significant risk to the electromagnetic switch, such as electromagnetic interference, are not likely to generate the same level of risk to the electromechanical switch. The electromechanical switch can be arranged to be normally open or normally closed, with the state of the switch changing in response to activation of the operating element, i.e. in response to the physical movement thereof.

Alternatively or additionally, the at least two switch elements may include the contactless switch and a further contactless switch. The two contactless switches may operate using the same principles and optionally also may use similar (or identical) components. This can simplify the construction of the call point. For example, the two contactless switches may both be optical switches, or some other type of contactless switch as discussed further below. The two contactless switches may include a contactless switch that is arranged to be normally closed and a contactless switch that is arranged to be normally open. Thus, the alarm condition may be triggered by opening of the normally close contactless switch or by closing of the normally open contactless switch. This acts as a fail-safe arrangement as well as enhancing the capabilities of the call point with respect to self-verification procedures. It will be appreciated that the state of the normally closed and normally open switches can be checked without activation of the operating element, with the ability to confirm that some aspects of the call point are operating effectively simply by checking the status of the two contactless switches and their respective electromagnetic circuits.

In example embodiments the manual call point comprises at least three switches, or only three switches, wherein the switches include first and second contactless switches along with an electromechanical switch. This allows for all of the various advantages discussed above to be combined, with enhanced capabilities for self-verification as well as increased reliability due to the presence of differing failure modes.

Various possible forms of contactless switch may be used for the contactless switch(es) of the at least two switches. For example, the contactless switch(es) may comprise optical switches, magnetic switches, radar devices, proximity sensors and so on. Suitable magnetic switches include switches using hall sensors. The contactless switch(es) may be provided by electromagnetic circuits comprising paired emitter and receiver components, such as optical emitter and receiver components. Photodiodes may be used as optical receiver components. The optical emitters may for example be lasers or lamps. In example embodiments the contactless switch(es) comprise a light emitting diode paired with a photodiode. It will be appreciated that this allows for a reliable low power arrangement for both normally open and normally closed arrangements.

The receiver and emitter components of the contactless switch(es) may be placed either side of a working path for the operating element, i.e. either side of a location occupied by the operating element during the normal condition or the alarm condition. The operating element may hence block the passage of electromagnetic radiation between the receiver and emitter components in order to change the state of the switch. In some example embodiments two or more contactless switches may share a common emitter component. For instance a manual call point may include one emitter component and two receiver components, with electromagnetic radiation passing from the one emitter to both the first and second receiver to form two contactless switches. The receiver components act to complete or break the circuit depending on the electromagnetic radiation received (or not received) from the common emitter. Alternatively, each receiver component may have a dedicated emitter component, such that each switch has both of an emitter component and a receiver component.

In example embodiments using two contactless switches with each having a respective emitter component (and a respective receiver component) an emitter component of one contactless switch may be placed on a first side of the operating element alongside a receiver component of the other contactless switch, with the receiver component of the one contactless switch being placed on a second side of the operating element alongside an emitter component of the other contactless switch. Thus, the respective emitters and receivers are diagonally apart from one another. This can facilitate a self-verification procedure such as that discussed below, since there is a potentially easier route for electromagnetic radiation such as light to pass from the emitter of one switch to the receiver of the other switch.

Advantageously, where two similar contactless switches are used, the call point or an associated external controller may be arranged to assess the interaction between components of the two contactless switches as a part of a self-verification procedure. Thus, the self-verification may include steps for cross-checking the operation of the two contactless switches, such as by using a receiver component of one switch to check the operation of an emitter component of the other switch. Since both the contactless switches will be housed within the same call point device, which generally has a restricted size, such as that defined by EN 54-11, then they will be in relatively close proximity and the underlying electromagnetic principles may allow for the assessment of the effect of adjacent switching components. For example, in the case of optical switches such as the light emitting diode and photodiode combination mentioned above, then the optical receiver component of one contactless switch may detect some of the light emitted by the optical emitter component of the other contactless switch, such as via visible light reflected and/or scattered within the call point. Similar effects may be present for other electromagnetic components, such as magnetic sensing devices.

A self-verification procedure for the call point may include detecting the condition of the normally closed contactless switch by sensing the interaction of the components of that switch via a receiver component of the normally closed contactless switch, and also detecting the condition of an emitter component of the normally open contactless switch via the same receiving component of the normally closed contactless switch. This can hence check that the emitter component of the normally open switch is operating, without the need to activate, i.e. physically move, the operating element. The self-verification procedure may alternatively or additionally comprise sensing the interaction of the components of the normally closed contactless switch via a receiver component of the normally closed contactless switch, and also detecting the condition of an emitter component of the normally closed contactless switch via the receiving component of the normally open contactless switch. This can check that the receiver component of the normally open contactless switch is operating, without the need to close the switch by activating the operating element.

The call point may include a controller, such as a microprocessor, for interaction with the switches during operation of the call point and/or for performing a self-verification procedure, such as a procedure discussed above. Alternatively or additionally the call point may be arranged for communication with an external controller for interaction with the switches during operation of the call point and/or for performing the self-verification procedure for the switches. The call point may be configured for wired and/or wireless communication with an external alarm system, which may comprise the external controller. The controller may be arranged to assess if an activation of the alarm condition is triggered with fewer than all of the switches changing state and, if so, to provide an alert indicating a possible failure. This allows for the manual call point to be inspected and, if needed, repaired or replaced in order to ensure that all of the switches, e.g. the two or three switches as discussed above, are operating correctly.

The operating element may include a mechanical component arranged for physical movement to trigger the alarm condition, wherein the mechanical component includes a section that will open or close the contactless switch(es). Thus, in the case of an optical switch or other line-of-sight electromagnetic switch the mechanical component may include a section that is opaque for the respective wavelength of electromagnetic radiation, e.g. opaque to light from light emitting diodes if used for an optical switch. In the case of other forms of switch the mechanical component may include a section that will trigger operation of the switch, such as a magnetic material to trigger a magnetic sensor.

The manual call point may include a frangible element that is arranged to break or displace during user interaction with the call point to trigger the alarm condition. The frangible element may for example be as discussed in EN 54-11. The frangible element may comprise a transparent element shielding the operating element.

In example embodiments a physical force is required to activate the operating element, such as a force applied by the user to physically move the operating element. Advantageously, the manual call point is able to withstand relatively small forces and/or impacts, with a force and/or impact larger than a threshold being needed to activate the operating element, and optionally also break or displace the frangible element if present. For example, the call point may be arranged to meet the requirements of EN 54-11 with respect to non-activation for a relatively small force. Thus, the call point may be arranged such that it does not activate the alarm condition when tested by a force applied perpendicular to the frangible element increasing at a rate not exceeding 5 Ns−1 until it reaches (22.5±2.5) N, maintained for 5 s then released at a rate not exceeding 5 Ns−1. Further, the call point may be arranged such that after this relatively small force is applied to the frangible element without operation the call point is still able to operate when an appropriate force is applied to the frangible element by the user, such as a force as imparted by the relevant test defined in EN 54-11.

Where a frangible element is used then breaking or displacing the frangible element may directly trigger activation of the operating element, such as by effecting the physical movement thereof. In the alternative, the call point may be arranged for indirect operation, where the frangible element must be broken and or displaced to access the operating element, with a separate manual activation of the operating element being required to trigger the alarm condition.

The manual call point may have a size and shape consistent with the requirements of applicable regulations. For example, the size and shape may be as required by EN 54-11. Thus, the manual call point may have a cuboid housing with a rectangular front face, such as a square front face with the housing comprising an outer wall enclosing all parts of the manual call point. The housing may be arranged to mount to a flat vertical surface, e.g. a wall of a building, with the front face sitting forward of the vertical surface by at least 10 mm or at least 15 mm. The operating element may be accessible and/or visible through the front face, such as through a window that may be provided by the frangible element. The front face may have a height and/or width be in the range 85 mm to 135 mm.

Viewed from a second aspect, the invention provides a method of use of a manual call point as described above in relation to the first aspect. The manual call point may include any other feature as discussed above.

The method may include operating the manual call point, wherein the method comprises triggering an alarm condition by physical movement of the operating element to change the state of at least one of the switches. The alarm condition may be triggered when any one of the switches changes state from its normal condition, such as by changing from normally closed to open or by changing from normally open to closed.

The method may include self-verification by the manual call point, wherein the self-verification includes steps to confirm that at least one of the switches is operational without activation of the operating element. The self-verification procedures, in the case of two contactless switches such as two optical switches, may include cross-checking the operation of the contactless switches via interaction between components of the two switches as discussed above. The method may include repeating the self-verification procedures periodically, for example as a part of a self-checking routine.

Thus, where a normally closed and a normally open contactless switch are used together then the method may include detecting the condition of the normally closed contactless switch by sensing the interaction of the components of that switch via a receiver component of the normally closed contactless switch, and also detecting the condition of an emitter component of the normally open contactless switch via the same receiving component of the normally closed contactless switch. The method may alternatively or additionally comprise sensing the interaction of the components of the normally closed contactless switch via a receiver component of the normally closed contactless switch, and also detecting the condition of an emitter component of the normally closed contactless switch via the receiving component of the normally open contactless switch.

Viewed from a third aspect, the invention provides a manual call point for a fire alarm system, the manual call point comprising: an operating element, wherein a physical movement of the operating element will trigger an alarm condition of the manual call point; and at least two switch devices, with each switch device being for completing or breaking a circuit in response to the physical movement of the operating element; wherein at least one of the switch devices is a contactless switch and the corresponding circuit includes an electromagnetic circuit that is completed or broken without mechanical contact from the operating element; wherein the at least two switch devices include the contactless switch and a further contactless switch, wherein the two contactless switches include a contactless optical switch that is arranged to be normally closed and a contactless optical switch that is arranged to be normally open; wherein an emitter component of one contactless optical switch is placed on a first side of the operating element alongside a receiver component of the other contactless optical switch, with the receiver component of the one contactless optical switch being placed on a second side of the operating element alongside an emitter component of the other contactless optical switch; and wherein the call point or an associated external controller is arranged to assess the interaction between components of the two contactless optical switches as a part of a self-verification procedure, and wherein the self-verification includes steps for cross-checking the operation of the two contactless optical switches, by using a receiver component of one contactless optical switch to check the operation of an emitter component of the other contactless optical switch.

