EP4592983A1

EP4592983A1 - Fire alarm call point based on conductive paint and method thereof

Info

Publication number: EP4592983A1
Application number: EP24153834.7A
Authority: EP
Inventors: Thomas Hanses; Luis Marques; Luis Moutinho
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2024-01-25
Filing date: 2024-01-25
Publication date: 2025-07-30

Abstract

The present disclosure relates to a fire alarm call point and a method for manual actuation to generate a fire alarm signal, comprising: an activation element for manual actuation; two electrical contacts; a conductive layer arranged on a face of the activation element; wherein the activation element is displaceable between an actuated state and an unactuated state, a resilient element to provide a return force to the activation element for returning the activation element to the unactuated state; wherein the conductive layer is arranged to connect the two electrical contacts in the actuated state of the activation element for generating a fire alarm signal upon actuation of the activation element.

Description

TECHNICAL FIELD

The present disclosure belongs to the technical field of a fire alarm call point.

BACKGROUND

The Manual alarm Call Point (MCP) is an essential component of fire detection alarm systems for largescale buildings and sites. Its main operation principle is based on the breakage or visible displacement of a frangible element by users to manually trigger a signal and alert the central controller about the existence of a nearby fire. The frangible element is a forming part of the MCP's front face and typically is made of glass or has the appearance of glass. After being physically broken or visibly displaced by change of position, it remains in that condition until replaced (non-resettable frangible element) or reset (resettable frangible element).
The European norms for MCP devices define two operation methods:

Type A - direct operation. Requires a single action to trigger the alarm signal, i.e., the alarm condition is automatic when the frangible element is broken or displaced;
Type B - indirect operation. Requires an additional manual operation by the user after breaking/displacing the frangible element. Here, users interact with an operating element, for example, a button, to perform the required additional action and trigger an alarm.

Figure 1 and Figure 2 highlight the principal components commonly found in existing commercial Type A and Type B MCPs. Commercial examples for both types include the Bosch FMC-210-XX family.
The operation principle of a non-resettable Type B MCP Figure 1 is simple. First, the user must break a glass pane 1 to gain access to the operating element that is typically a pressable button 2. The user then activates it (e.g., presses the button) to trigger the alarm event. A mechanism then holds the operating element in its active state. An openable enclosure 3 allows the responsible actors to replace the glass pane and reset the device. The operation principle of non-resettable Type A MCPs Figure 1 is very similar. However, the operating element is now automatically activated upon the glass pane breaking, without any additional user action. This operation is typically implemented by having a button held pressed by the glass pane itself. The button springs up automatically when the glass is broken, triggering an alarm.
The structure and operation principle of resettable Type A MCPs Figure 2 is slightly more complex with respect to its aforementioned counterparts. In these devices, the glass pane 5 is kept pushed against a push/limit switch 4 by some mechanical means 6, typically a spring-based device and many other auxiliary parts. When pressed by the user, the pane is displaced and the push/limit switch is no longer pressed, thus triggering an alarm event. A special tool is used by the responsible actors to reset and rearm the pane.
Document GB2439408A discloses a break pane of plastics material for an alarm call point device with at least two sub-regions and with at least one predetermined separating point is disclosed. The predetermined separating point extends at least in portions between the at least two sub-regions. The predetermined separating point is formed so that the at least two sub-regions are separated from one another upon application of a predetermined force, such that the predetermined separating point is formed so as to be only irreversibly separable. Also disclosed is an alarm call point housing comprising a break pane in which the break pane can be inserted into the closed call point housing from the outside and a method of forming a break pane comprising two different regions, each of a different material, wherein the two different regions are joined in a common injection mould.
Document US7414499B2 discloses a ground fault circuit interrupter device having a single actuator for sequentially activating a circuit interrupting portion when the device is in a reset condition and a reset portion when the device is in a tripped condition. The circuit interrupting portion breaks a conductive path between a line terminal and load terminal upon the occurrence of a predetermined condition thereby placing the device in the tripped condition and the reset portion reestablishes the conductive path between the line terminal and the load terminal thereby placing the device in the reset condition.
These facts are disclosed in order to illustrate the technical problem addressed by the present disclosure.

GENERAL DESCRIPTION

Due to its operation principles, commercially available MCPs rely on a significant number of mechanical components, including switches, springs, and other small parts. Besides being less reliable than electronic based circuitry, these components demand higher assembly and maintenance complexity, create bulkier devices (depth-wise), and significantly increase the number of plastic parts and raw materials (potential higher production costs).
The present disclosure proposes the use of conductive paint as an enabler for possible new operation methods and designs for all types of MCP devices, simplifying assembly and maintenance, increasing reliability, and reducing the number of parts, raw materials, and (potentially) device footprint. To the best of our knowledge, this is a novel approach, not yet found in competitors' commercial solutions.
Conductive paint (also known as electrical paint or ink) could be used in many industrial applications as an economical way to lay down conductive traces and build flexible electrical printed circuit boards. Windshield defrosters, 3-D printed antennas, ship-side wave and fatigue crack sensors, "Do It Yourself" (DYI) electric wires, capacitive sensors, and light switches, smart infrastructure, are just some examples of existing applications of conductive paint. The present disclosure proposes to use it to implement one or more operation elements used by Type A and Type B MCPs. In particular, it is proposed to enhance frangible elements with sensing capabilities and replace mechanical-bases operating elements with capacitive ones.
The present disclosure discloses a fire alarm call point for manual actuation, especially by a user, to generate a fire alarm signal, comprising: an activation element for manual actuation, especially by the user; two electrical contacts; a conductive layer arranged on a face of the activation element; wherein the activation element is displaceable between an actuated state and an unactuated state, preferably a resilient element to provide a return force to the activation element for returning the activation element to the unactuated state; wherein the conductive layer is arranged to connect the two electrical contacts in the actuated state of the activation element for generating a fire alarm signal upon actuation of the activation element and/or the conductive layer is arranged to disconnect the two electrical contacts in the actuated state of the activation element for generating a fire alarm signal upon actuation of the activation element.
In an embodiment, the conductive layer is arranged on a portion of the face of the activation element to connect the two electrical contacts in the actuated state of the activation element.
In an embodiment, the conductive layer is arranged as a line on the face of the activation element to connect the two electrical contacts in the actuated state of the activation element.
In an embodiment, the conductive paint layer overlaps the metallic contacts.
In an embodiment, the conductive layer is a conductive-paint layer.
In an embodiment, the actuated state is a pressed state of the activation element by the user.
In an embodiment, the conductive layer is arranged on a back face of the activation element.
In an embodiment, the two electrical contacts are oppositely positioned relative to the activation element.
In an embodiment, the fire alarm call point further comprises a housing comprising a front face and a back face.
In an embodiment, the activation element is exposed on the front face of the housing for manual actuation.
In an embodiment, the conductive layer is arranged to disconnect the two electrical contacts in the unactuated state of the activation element.
In an embodiment, the fire alarm call point further comprises a breakable glass or protective cover at least partially covering the activation element.
In an embodiment, the fire alarm call point further comprises a data processor configured to initiate communication with a central monitoring system upon actuation.
In an embodiment, the resilient element is an elastic element, in particular a spring.
It is also disclosed a computer-based method for providing a fire alarm warning of a manual actuation by a user of a fire alarm call point, said fire alarm call point comprising an activation element for manual actuation by the user; two electrical contacts; a conductive layer arranged on a face of the activation element, preferably a resilient element and an electronic data processor, said method comprising the steps of: actuating the activation element; generating a fire alarm signal.

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures provide preferred embodiments for illustrating the disclosure and should not be seen as limiting the scope of invention.

Figure 1 : Schematic representation of main components of non-resettable Type A/Type B MCPs.
Figure 2 : Schematic representation of an embodiment of main components of resettable Type A MCPs B MCPs.
Figure 3 : Schematic representation of an embodiment of principle operation of an electrical circuit based on conductive paint.
Figure 4 : Schematic representation of an embodiment MCP based on a frangible element with painted electrical wire.
Figure 5 : Schematic representation of an embodiment of frangible element with redundant painted wires. Enclosure concealing wires.
Figure 6 : Schematic representation of an embodiment of operating element based on conductive paint.
Figure 7 : Schematic representation of an embodiment of pressable button commonly found in Type B MCP devices.
Figure 8 : Schematic representation of an embodiment of a MCP with capacitive interface as operating element.

DETAILED DESCRIPTION

The present disclosure relates to a fire alarm call point for manual actuation by a user to generate a fire alarm signal.
Figure 3 shows by applying a layer of conductive paint on a surface, it is possible to create a "wire" across it that can be used to "close" a powered electrical circuit and enable an electrical current flow. If the continuity of the "wire" is destroyed (e.g., a segment of the surface is cut or broken), the electrical circuit loop is interrupted, and no electrical current exists. Thus, a device can ascertain if the surface has been destroyed by sensing the current across the painted wire extremities.
As illustrated by Figure 4 , one of the main ideas are to paint such a wire 2 over the MCPs' frangible element. The paint can be applied on the top or bottom surface, or using a sandwiched approach (i.e., in between two surfaces comprising the frangible element). Additionally, the wire can take multiple shapes and forms (e.g., as a logo, message, etc.), and multiple wires could be painted, for example, for redundancy purposes Figure 5 . Finally, in case transparent frangible elements are desired, wires can be painted along their extremities and concealed by the MCPs' enclosure.
The extremities of the painted wired connect to an electric circuitry via metallic contacts 3. The wire extremities and contacts must not be soldered or attached using connectors to allow easy replacement during maintenance and, more importantly, to allow the frangible element to be physically dislodged (the use-case for this is explained later on). Instead, these must be kept in contact only by the MCP's enclosure (e.g., via mechanical pressure). The electric circuitry is responsible for sensing the electrical current and reporting its status to a fire detection system's controller node. This circuitry can have many implementations, from a simple 4-20mA current loop connected to a sensing module of the controller node, to an embedded microcontroller within the MCP that communicates with the controller via a wired fieldbus or wireless communication.
For non-resettable, Type A MCPs, the "sensing" frangible element replaces the standard frangible element, the mechanical button, and other associated auxiliary parts. The operation principle is simple: the user breaks the frangible element, destroying the painted wire(s) during the process. The connected electrical circuit will then detect the lack of current across the wire(s) and notify the central controller to trigger a fire alarm. Broken frangible elements can be replaced using the same approaches found in traditional MCPS, that is, using an openable enclosure (door). This openable door can also be exploited to execute periodic maintenance tests as required by the EN-54 norms: a mechanical design can be made in which the contact between painted wires and metallic contacts is broken upon opening the door. For example, the design could be as simple as placing the metallic contacts on the inside of the door in such a way that they rest on top of the wire(s) painted on the top face of the frangible element. Alternatively, a design where a special external key can be used to break the contact can be exploited.
For resettable, Type A MCPs, the "sensing" frangible element also replaces the standard element and the mechanical button. However, the operation principle now relies on the physical displacement of the frangible element so it is possible to disconnect one or both extremities of the painted wire(s) from the metallic contacts. For this purpose, the traditional spring-based approaches can be used. Alternatively, the wire(s) could be painted on the top surface of the frangible element and the metallic contacts placed on the inside of the top face of the MCP's enclosure so they are both in contact. Here, an appropriate mechanical design should allow users to dislodge the frangible element on the z-axis when pressed, breaking the contact between the wire(s) and contacts, thus triggering an alarm. For rearm and periodic maintenance purposes, an openable enclosure or other traditional approaches can be used.
Type B MCPs require two user actions before triggering an alarm. Therefore, the use of a single "sensing" frangible element alone is not sufficient, being still required an operating element such as, for example, a pressable button as in traditional devices. Accordingly, it is disclosed two aspects to replace and realize this operating element: (i) replace the pressable button with a capacitive interface using conductive paint , (ii) use a second "sensing" frangible element as operating element. In the latter, an aspect is to implement a mechanical design that allows pushing the operating element across the z-axis so that the painted wire(s) make contact with metallic contacts on the back face of the enclosure Figure 6 . The operating element can take many sizes and shapes, from simple rectangles as in the example of Figure 6 , to small button-like pieces; the operation principle should still be identical.
Additionally, the "sensing" capabilities of the primary frangible element can be used to enhance the functionalities of Type B MCPs. For example, it can be used for diagnostic/maintenance purposes by allowing the central controller to know the physical status (broken or intact) of the element without any visual inspection, to remotely assess if the device has been tampered (e.g., enclosure opened), or to trigger fire pre-alarms (e.g., the user broke the frangible element but failed to act on the operating element or the operating element itself didn't work as intended).
Conductive paint can also be used to replace existing mechanical operating elements, namely the pressable buttons commonly found in Type B MCPs Figure 7 . An aspect is to use conductive paint to create a capacitive interface as in which users can interact with (e.g., touch it with a finger) to trigger an alarm. This interface could be designed, for example, as a simple capacitive surface in the shape of a button. The activate position indication required by the norms can be signalled by a visual cue, for example, by switching a colored LED placed in the center of the capacitive interface "ON" Figure 7 .
""""-""The term "comprising" whenever used in this document is intended to indicate the presence of stated features, integers, steps, components, but not to preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof.
The disclosure should not be seen in any way restricted to the embodiments described and a person with ordinary skill in the art will foresee many possibilities to modifications thereof. The above-described embodiments are combinable. The following claims further set out particular embodiments of the disclosure.

Claims

Fire alarm call point for manual actuation to generate a fire alarm signal, comprising:
an activation element for manual actuation;

two electrical contacts;

a conductive layer arranged on a face of the activation element;

wherein the activation element is displaceable between an actuated state and

an unactuated state,

wherein the conductive layer is arranged to connect the two electrical contacts in the actuated state of the activation element for generating a fire alarm signal upon actuation of the activation element and/or the conductive layer is arranged to disconnect the two electrical contacts in the actuated state of the activation element for generating a fire alarm signal upon actuation of the activation element.
Fire alarm call point according to the previous claim wherein the conductive layer is arranged on a portion of the face of the activation element to connect the two electrical contacts in the actuated state of the activation element.
Fire alarm call point according to any of the previous claims wherein the conductive layer is arranged as a line on the face of the activation element to connect the two electrical contacts in the actuated state of the activation element.
Fire alarm call point according to any of the previous claims wherein the conductive paint layer overlaps the metallic contacts.
Fire alarm call point according to any of the previous claims wherein the conductive layer is a conductive-paint layer.
Fire alarm call point according to any of the previous claims wherein the actuated state is a pressed state of the activation element by a user.
Fire alarm call point according to any of the previous claims wherein the conductive layer is arranged on a back face of the activation element.
Fire alarm call point according to any of the previous claims wherein the two electrical contacts are oppositely positioned relative to the activation element.
Fire alarm call point according to any of the previous claims further comprising a housing comprising a front face and a back face.
Fire alarm call point according to the previous claim wherein the activation element is exposed on the front face of the housing for manual actuation.
Fire alarm call point according to any of the previous claims wherein the conductive layer is arranged to disconnect the two electrical contacts in the unactuated state of the activation element.
Fire alarm call point according to any of the previous claims further comprising a breakable glass or protective cover at least partially covering the activation element.
Fire alarm call point according to any of the previous claims further comprising a data processor configured to initiate communication with a central monitoring system upon actuation.
Fire alarm call point according to any of the previous claims, wherein the resilient element is an elastic element, in particular a spring.
Method for providing a fire alarm warning of a manual actuation by a user of a fire alarm call point, said fire alarm call point comprising an activation element for manual actuation by the user; two electrical contacts; a conductive layer arranged on a face of the activation element and an electronic data processor, said method comprising the steps of:
actuating the activation element; generating a fire alarm signal.