Call point for an alarm system

Abstract

 A call point for use in fire or intruder alarm systems, said call point comprising a displaceable or frangible element 4;40, at least a portion of which is manually displaceable in order to actuate a switch 8 to indicate an alarm condition, the element 4;40 being displaceable between a first position and a second position, the switch 8 being actuated when the element 4;40 moves from its first position to its second position, a spring 9 biasing the element from its first to its second position, the call point further comprising a latch 11 having an abutment 12 engageable against the element 4;40 to maintain the element 4;40 in its first position against the action of the spring 9, the latch 12 being rotatable by a key 6 from an active position wherein the abutment 12 engages the element 4;40 to an inactive position wherein the element 4;40 is free to move to its second position under the action of the spring 9, in order to actuate the switch 8 and thus test the alarm system.

Description

[0001] The present invention relates to a call point for an alarm system such as a fire alarm system or an intruder alarm system more particularly to a manually operable call point which can be actuated and subsequently reset to test the alarm system to which it is connected.

[0002] Fire alarm systems frequently incorporate one or more manually operable call points which can be actuated by a person who discovers a fire in order to activate a fire alarm. Such call points have traditionally incorporated a glass plate or element accessible through a window, a spring loaded switch resting on an edge of the glass plate. In order to actuate the alarm system a person strikes the glass plate through the window, breaking the plate such that the switch is released. The status of the call point can be easily visually determined by a simple visual assessment of the condition of the glass plate.

[0003] A problem with such existing frangible type or break glass call points is that the call point cannot normally be actuated in order to test the alarm system without requiring the replacement of the glass plate which must be broken in order to actuate the call point. In view of this problem call points have been developed using resettable non-frangible actuating means which can be activated and reset repeatedly without requiring replacement of a frangible element. An example of such a resettable call point is shown in GB 2024521. The construction of the call point is essentially similar to that of the traditional frangible type. However, the frangible glass plate is replaced by a resilient plate 16 which can be deformed to release the switch 15 and activate the alarm system. A tool can be used to reset the switch whereupon the plate 16 restores itself to its initial configuration. A problem with this type of non-frangible call point is that the status of the call point cannot be easily determined by a cursory visual inspection.

[0004] According to the present invention there is provided a call point for use in fire or intruder alarm systems, said call point comprising a displaceable or frangible element, at least a portion of which is manually displaceable in order to actuate a switch to indicate an alarm condition.

[0005] In a preferred aspect said displaceable element is displaceable between a first position and a second position, the switch being actuatable when the displaceable element moves from its first position to its second position, first biasing means biasing the displaceable element from its first to its second position, the call point further comprising a latch having an abutment engageable against a portion of the displaceable element to maintain the displaceable element in its first position against the action of the first biasing means, the latch being manually moveable from an active position wherein the abutment engages said portion of the displaceable element to an inactive position wherein the displaceable element is free to move to its second position under the action of the first biasing means, in order to actuate the switch and thus test the alarm system.

[0006] In a preferred embodiment the latch comprises an elongate hollow cylindrical body rotatably mounted within a housing of the call point for rotation about a longitudinal axis of the cylindrical body, said axis of rotation of the latch being arranged substantially parallel with the direction of movement of the displaceable element from its first to its second position, the abutment comprising a segment of an end of the latch adjacent said portion of the displaceable element, said segment having an axial extension greater than that of the remainder of said end of the latch, whereby the latch is rotatable between its active position, wherein a portion of the displaceable element engages the abutment to maintain the displaceable element in its first position, and its inactive position, wherein the abutment is displaced out of alignment with said portion of the displaceable element such that the displaceable element can move past the abutment, under the action of the first biasing means, to its second position.

[0007] Preferably the latch is operable by means of a key insertable through an aperture in the housing into the hollow centre of the of the latch, said key having one or more radially extending protrusions engaging corresponding slots or apertures in the inner surface of the latch such that the latch can be moved from its active to its inactive position by rotation of the key once inserted into the latch to a depth wherein said protrusions thereof engage said slots of the latch, whereby the abutment is moved out of alignment with said portion of the displaceable element such that the element moves from its first to its second position to actuate the switch in order to test the alarm system.

[0008] In order to reset the call point the key may be inserted further through the hollow centre of the latch until the end thereof engages said portion of the displaceable element, whereby further inward movement of the key urges the displaceable member from its second to its first position against the action of the first biasing means. The latch may be moved from its inactive position to its active position by further rotation of the key, with the key remaining fully inserted such that the displaceable element is held in its first position. However, in a preferred embodiment a second biasing means is provided biasing the latch from its inactive to its active position, the protrusions of the key being arranged such that said protrusions disengage said corresponding slots or apertures in the inner surface of the latch to permit free rotation of the latch relative to the key when the key is fully inserted to push the displaceable member to its first position such the latch rotates from its inactive position to its active position under the action of the second biasing means when the key is pushed fully in so as to reset the call point.

[0009] According to a further preferred aspect of the invention the call point further includes an indicating means viewable through a viewing window, the indicating means being obscured by the displaceable element when the displaceable element is in its first position, the indicating means being visible through the viewing window when the displaceable element is in its second position in order to provide a visible indication of the actuation of the call point. Preferably the indicating means comprises a label applied to an inner wall of a housing of the call point behind at least a portion of the viewing window.

[0010] The present invention will be described further, by way of example, with reference to the accompanying drawings, in which:-

Fig. 1 is a perspective view of a call point according to the invention;

Fig. 2 is a perspective view of the call point of Fig. 1 with the front cover removed;

Fig. 3 is a plan view of a section of the call point of Fig. 2 with the plate in its first position;

Fig. 4 is plan view of the call point of Fig. 2 with the plate in its second position;

Fig. 5 is a perspective view of a section of the call point of Fig. 2 showing operation of the test mechanism;

Fig. 6 is a perspective view of a section of the call point of Fig. 2 showing operation of the resetting mechanism;

Fig. 7 is a perspective view of a call point according to the invention of the frangible or break glass type;

Fig. 8 is a plan view of the call point of Fig. 1 showing the displaceable plate in its first position; and

Fig. 9 is a plan view of the call point of Fig. 1 showing the plate in its second position.

[0011] As shown in Fig. 1, a call point according to the invention comprises a housing 1 fitted with a removable cover 2, the cover 2 having a viewing window 3 in a front surface thereof. A displaceable element or plate 4 is movably mounted inside the housing 1, the plate 4 being visible and accessible through the viewing window 3. An aperture 5 is provided in a lower side of the housing 2 though which is insertable a test and resetting key 6 as will be described below.

[0012] Figs. 2, 3 and 4 show the call point of Fig. 1 with the cover 2 removed to enable the internal components of the call point to be viewed. The plate 4 comprises a rectangular planar member formed from a resilient material, said plate 4 being moveably mounted in the housing 1 such that the plate 4 is displaceable between a first position, shown in Fig. 3, wherein the upper edge of the plate 4 engages a spring loaded trigger 7 of a switch 8 to hold the switch 8 in an open position whereby the alarm is deactivated, and a second position, shown in Fig. 4, wherein the trigger 7 of the switch 8 is released, causing the switch 8 to close thus activating the alarm. A compression spring 9 is mounted in the housing 1 acting between a wall of the housing 1 and an extension 10 of the plate 4, whereby the plate is biased towards its second position. A latch 11 having an abutment 12 engageable against the lower edge the plate 4 is rotatably mounted in a lower part of the housing 1 of the call point to maintain the plate 4 in its first position against the action of the spring 9, the latch 11 being manually rotatable from an active position wherein the abutment 12 is aligned with and engages the lower edge of the plate 4 to an inactive or test position, wherein the plate 4 is free to move past the abutment 12 to its second position under the action of the spring 9 in order to actuate the switch and thus test the alarm system.

[0013] As can be seen from Figs. 5 and 6, the latch 11 comprises an elongate hollow cylindrical body rotatably mounted in the housing 1 of the call point for rotation about the longitudinal axis of the cylindrical body, said axis of rotation of the latch 11 being arranged substantially parallel with the direction of movement of the plate 4 from its first to its second position, the abutment 12 comprising a segment of an end of the latch 11 adjacent the lower edge of the plate 4, said segment having an axial extension greater than that of the remainder of said end of the latch 11, whereby the latch 11 is rotatable between its active position, wherein the lower edge of the plate 4 engages the abutment 12 to maintain the plate 4 in its first position, and its inactive or test position, wherein the abutment 12 is displaced out of alignment with said portion of the plate 4 such that the plate 4 can move past the abutment 12, under the action of the spring 9, to its second position. A spring 13 is mounted on the latch 11 to bias the latch 11 towards its active position.

[0014] In normal operation, in order to activate the call point in the event of a fire being discovered, the user presses the centre of the plate 4 visible through the viewing window 3. The plate 4 is supported on its rear face adjacent its side edges by means of support members 14 (see Fig. 2) provided on the housing. Accordingly, manual pressure applied to the centre of the plate 4 causes the centre of the plate 4 to resiliently deflect inwardly such that the lower edge of the plate 4 is moved out of alignment with the abutment 12 provided on the latch 11, thereby releasing the plate 4 from the abutment 12 and allowing the plate 4 to move to its second position under the action of the spring 9, thus releasing the trigger 7 of the switch 8 and actuating the alarm.

[0015] Once actuated, the call point can be reset by inserting the key 6 into the aperture 5 in the housing 2 and through the latch 11 so that the end of the key 6 engages the lower edge of the plate 4 and pushes the plate 4 past the abutment 12 of the latch 11 and back into its first position. The resilience of the plate 4 causes the plate to move back into engagement with the abutment 12 of the latch 11 once the plate 4 has been pushed back up into its first position by means of the key 6.

[0016] In order to test the call point, the key 6 is partially inserted into the aperture 5 in the housing 2 into the hollow centre of the of the latch 11 to the position shown in Fig. 5, said key 6 having opposed radially extending protrusions 15 engaging corresponding slots 16 in the inner surface of the latch 11 such that the latch 11 can be rotated from its active to its inactive or test position by rotation of the key 6 after insertion of the key 6 into the latch 11 to a depth wherein said protrusions 15 thereof engage said slots 16 of the latch 11, whereby the abutment 12 is moved out of alignment with the lower edge of the plate 4 such that the edge of the plate 4 can move past the abutment 12 allowing the plate 4 to move from its first to its second position under the action of the spring 9 to actuate the switch 8 in order to test the alarm system.

[0017] In order to reset the call point following such a test operation the key 6 is inserted further through the hollow centre of the latch 11 until the end thereof engages the lower edge of the plate 4, whereby further inward movement of the key pushes the plate 4 back into its first position against the action of the spring 9, as shown in Fig. 6. The protrusions 15 of the key 6 are arranged such that said protrusions 15 disengage said corresponding slots 16 in the inner surface of the latch 11 to permit free rotation of the latch 11 relative to the key 6 when the key 6 is fully inserted to push the lower edge of the plate 4 clear of the abutment 12 of the latch 11 such that the latch 11 is free to rotate from its inactive position to its active position under the action of the spring 13.

[0018] Fig. 7. shows the call point according to the invention using a frangible glass plate 40 in place of the resilient plate 4 shown described above. As discussed previously, the frangible type of call point may be specified where it is necessary to quickly establish the status of the call point by a quick visual inspection. A shown in Fig. 7, when the glass plate 40 is broken by applying pressure thereto the central region of the plate 40 moves inwardly such that the upper edge of the plate releases the trigger 7 of the switch 8 actuating the alarm. In order to test the call point without breaking the glass plate the test and resetting key 6 can be used in exactly the same way as described above with reference to Figs. 5 and 6, the plate 40 being displaceable between its first and second positions by use of the key 6 in order to test and subsequently reset the call point as described above.

[0019] As described above, a problem associated with the resettable type of call point using a resilient plate 4 as shown in Figs. 1 to 6, is that it can be difficult to establish the status of the call point by a brief visual inspection since the plate 4 is not broken during operation of the call point. This problem is addressed in the present invention as shown in Figs. 8 and 9 by providing a brightly coloured label 17 on the rear face of the housing 1 behind the plate 4, said label 17 being obscured by the plate 4 when the plate 4 is in its first position as shown in Fig. 8, the body of the plate 4 being opaque or non-transparent, the label 17 being visible through the viewing window 3 when the plate 4 is in its second position as shown in Fig. 9, by virtue of the extension 10 of the plate 4, against which the spring 9 acts, being formed from a transparent material or having a viewing aperture therein, such that the label 17 is visible through the extension 10 of the plate 4 to provide a visual indication of the actuation of the call point.

Claims

1. A call point for use in fire or intruder alarm systems, said call point comprising a displaceable or frangible element, at least a portion of which is manually displaceable in order to actuate a switch to indicate an alarm condition.

2. A call point as claimed in claim 1, wherein said displaceable element is displaceable between a first position and a second position, the switch being actuatable when the displaceable element moves from its first position to its second position, first biasing means biasing the displaceable element from its first to its second position, the call point further comprising a latch having an abutment engageable against a portion of the displaceable element to maintain the displaceable element in its first position against the action of the first biasing means, the latch being manually moveable from an active position wherein the abutment engages said portion of the displaceable element to an inactive position wherein the displaceable element is free to move to its second position under the action of the first biasing means, in order to actuate the switch and thus test the alarm system.

3. A call point as claimed in claim 2, wherein the latch comprises an elongate hollow cylindrical body rotatably mounted within a housing of the call point for rotation about a longitudinal axis of the cylindrical body, said axis of rotation of the latch being arranged substantially parallel with the direction of movement of the displaceable element from its first to its second position, the abutment comprising a segment of an end of the latch adjacent said portion of the displaceable element, said segment having an axial extension greater than that of the remainder of said end of the latch, whereby the latch is rotatable between its active position, wherein a portion of the displaceable element engages the abutment to maintain the displaceable element in its first position, and its inactive position, wherein the abutment is displaced out of alignment with said portion of the displaceable element such that the displaceable element can move past the abutment, under the action of the first biasing means, to its second position.

4. A call point as claimed in claim 3, wherein the latch is operable by means of a key insertable through an aperture in the housing into the hollow centre of the of the latch, said key having one or more radially extending protrusions engaging corresponding slots or apertures in the inner surface of the latch such that the latch can be moved from its active to its inactive position by rotation of the key once inserted into the latch to a depth wherein said protrusions thereof engage said slots of the latch, whereby the abutment is moved out of alignment with said portion of the displaceable element such that the element moves from its first to its second position to actuate the switch in order to test the alarm system.

5. A call point as claimed in claim 4, wherein, in use, in order to reset the call point the key is inserted further through the hollow centre of the latch until the end thereof engages said portion of the displaceable element, whereby further inward movement of the key urges the displaceable member from its second to its first position against the action of the first biasing means.

6. A call point as claimed in claim 5, wherein the latch is moved from its inactive position to its active position by further rotation of the key, with the key remaining fully inserted such that the displaceable element is held in its first position.

7. A call point as claimed in any preceding claim, wherein the call point further includes an indicating means viewable through a viewing window, the indicating means being obscured by the displaceable element when the displaceable element is in its first position, the indicating means being visible through the viewing window when the displaceable element is in its second position in order to provide a visible indication of the actuation of the call point.

8. A call point as claimed in claim 7, wherein the indicating means comprises a label applied to an inner wall of a housing of the call point behind at least a portion of the viewing window.

Drawing