EP2481064B1

EP2481064B1 - An elongate switch for use in an alarm sytem

Info

Publication number: EP2481064B1
Application number: EP10754363.9A
Authority: EP
Inventors: Christopher M Butler
Original assignee: Cronapress Ltd
Current assignee: Cronapress Ltd
Priority date: 2009-09-24
Filing date: 2010-09-07
Publication date: 2014-01-01
Anticipated expiration: 2030-09-07
Also published as: GB201110067D0; AU2010299656A1; GB2477486A; GB2477486B; AU2010299656B2; WO2011036470A1; EP2481064A1; GB0916756D0

Description

The present invention relates to a switch. In particular, the present invention relates to an elongate switch for use as part of an alarm system.
Switches are used in electric circuits to allow a user to selectively open and close an electric circuit. One type of switch is a continuous strip switch which allows a user to activate the switch by manipulating any part of the length of the switch.
A known continuous strip switch comprises a rubber tubular body, having two sections of copper wire cored conductive rubber and an insulating section of non-conductive rubber. The cross-sectional shape of the first section of copper wire cored conductive rubber is part circular and the cross-sectional shape of the second section of copper wire cored conductive rubber is generally triangular. The first and second sections are configured so that the point of the triangle of the second section extends towards the concave face of the part circular first section. In its inactive state the first and second sections of copper wire cored conducting rubber are held apart by the rubber tubular body. However, the tubular body can be compressed so as to bring the concave face of the first section into contact with the point of the triangular shaped second section of copper wire cored conductive rubber, so as to close the switch. There are difficulties in manufacturing such continuous strip switches. Furthermore, such switches can easily be activated inadvertently.
UK patent application GB-2440594-A (commonly owned by the applicant for the present invention) discloses an improved switch comprising: a substantially tubular body resiliently deformable between a non-deformed state and a deformed state; and a first non-apical electrical contact strip secured to a first internal wall of the substantially tubular body and a second non-apical electrical contact strip secured to a second internal wall of the substantially tubular body so that the first non-apical electrical contact strip and second non-apical electrical contact strip are in a spaced apart relationship in the non-deformed state and are in contact in the deformed state.
The switch of GB-2440594-A secures first and second non-apical electrical contact strips to internal walls of a substantially tubular body thereby providing a reliable switch which is not easily accidentally activated. The use of non-apical electrical contact strips allows an appropriate contact strip separation distance to be achieved which reduces inadvertent activation. Furthermore, the electrical contact strips are protected from the environment by the substantially tubular body.
Referring to figure 1, this shows a schematic perspective view of a switch 2 according to GB-2440594-A . The switch 2 generally comprises a substantially tubular body 4 and first and second metal contact strips 6, 8. The first and second contact strips 6, 8 are substantially planar in configuration.
The tubular body 4 comprises a first body part 10 and a second body part 12. The first body part 10 comprises an elongate, solid member, on a first elongate face of which is mounted the first contact strip 6.
The second body part 12 has an open cross-sectional shape. The second body part 12 has a planar base 14 extending between the first ends of first and second arcuate walls 16, 18 that are opposite one another. Extending from each of the second ends of the arcuate walls 16, 18 are first and second upwardly dependent planar walls 20, 22. The planar walls 20, 22 extend substantially parallel to each other. The second contact strip 8 is mounted on the base 14. The first body part 10 can fit snugly between the first and second planar walls 20, 22. The contact strips 6, 8 comprise strips of copper with a laminated polyester backing.
To assemble the switch 2, the first contact strip 6 is welded to the base of the first body part 10 and the second contact strip 8 is welded to the first elongate face of the second body part 12. Once the contact strips 6, 8 have been welded to their respective body parts 10, 12, the planar walls 20, 22 of the second body part 12 are welded to side faces of the first body part 10. Once assembled the first and second contact strips 6, 8 are held apart by the body 4.
It is known to use a continuous strip switch as part of an alarm system. For instance, a continuous strip switch may be provided extending along a wall of a room or corridor such that in an emergency the strip may be hit or otherwise manipulated by a user at any point along the length of the switch thereby activating the switch. The switch is coupled to an audible or visible alarm, or otherwise arranged to trigger further action, for instance summoning assistance. One exemplary application of such an alarm system is in a police station in order to summon assistance in the event of a violent or non-cooperative prisoner.
A continuous strip generally of the form illustrated in figure 1 may be used as part of such an alarm system. The continuous strip switch may be integrated into a metal or plastic channel to support the switch upon the wall, and an upper surface of the switch may be shaped so as to be readily struck by a user in order to activate the switch.
The alarm signal triggered by striking the continuous strip switch may not be visible or audible to the person striking the switch. For instance, it may trigger an alarm in another part of the building. Furthermore, depending upon the system to which the alarm is connected there may be a time delay in activating the alarm after the switch has been pressed. Consequently, it may not be immediately apparent to the user that the alarm has activated once the switch has been pressed. The person triggering the alarm may therefore press the switch repeatedly until assistance arrives, when ideally they should be concentrating on the situation at hand.
Furthermore, for known continuous strip switches forming part of alarm systems, there may be no way of knowing whether the switch is operating correctly other than to trigger the alarm.
US-5260530-A discloses an illuminated, press-at-any-point switching device which can be actuated by the application of or the removal of pressure at substantially any point along a surface of the switching device. The illuminated, press-at-any point switching device includes a cover, an illuminating member, a switching assembly and a mounting surface. The cover holds the components of the device onto the mounting surface. The device may also include a separate signal indicia to indicate the operation of the device.
It is an object of embodiments of the present invention to obviate or mitigate one or more of the problems of the prior art, whether identified herein or elsewhere.
According to a first aspect of the present invention there is provided a switch according to claim 1.
An advantage of the first aspect of the present invention is that the switch incorporates an elongate light source arranged to illuminate at least part of the switch after the switch has been activated by a user pressing the body so as to provide an immediate indication that the switch has been triggered. This is particularly advantageous when the switch forms part of a personal safety alarm system. The elongate light source may also continuously illuminate the switch so as to provide an indication that it is operating correctly. When a press of the hollow body is detected the illumination of the switch may be varied.
The elongate light source may be further arranged to provide a clear indication that the switch is operating correctly. For instance, in embodiments of the present invention the switch may be continuously illuminated unless a fault in the contact strips is detected. The continuously illuminated switch serves as a guide to indicate to the user where the switch is to be pressed to trigger the alarm. In particular, in embodiments of the present invention, the portion of the switch which is illuminated is the elongate body. That is, the portion of the switch which can be pressed (the body and not, for instance a support channel) is illuminated, and no other portion of the switch.
As well as serving as an indication that the switch is operating correctly, the continuously illumination is intended to reassure potential users that assistance may be summoned, and possible to discourage others from behaviour that may cause a user to want to summon assistance. Furthermore, the change in illumination when the alarm is triggered (for instance flashing lights instead of continuous illumination, and / or a change of colour) may also have a deterrent effect upon an attacker.
Advantageously, embodiments of the present invention also provides a robust switch suitable for use in an alarm system that is easy to install and maintain, not susceptible to damage from impact from objects and easy to clean by presenting a smooth exterior profile.
The first and second electrical contact strips may extend along at least part of the body. The elongate body may be hollow and may be resiliently deformable between a non- deformed state and a deformed state. The first and second electrical contact strips may be secured to first and second internal walls of the hollow body so that the first electrical contact strip and second electrical contact strip are in a spaced apart relationship in a non- deformed state and are in contact in the deformed state.
The elongate light source may comprise an array of discrete light sources.
The channel may be arranged to be secured to a solid object such that the open part of the channel faces outwards from the solid object and extends along the length of the switch.
The first and second contact strips may be substantially diametrically disposed in the hollow body. The first and second contact strips may be aligned with the open part of the channel and the elongate light source is located underneath the contact strips. The hollow body may be deformable manually by pressing in a direction substantially perpendicular to the contact strips.
According to a second aspect of the present invention there is provided an alarm system comprising: a switch according to any one of the preceding claims; and a control unit coupled to the switch; wherein the control unit is arranged to detect when the body is pressed and to control the elongate light source to adjust the illumination of the body according to whether a press of the hollow body is detected.
The contact strips may be coupled at a first end to the control unit such that the contact strips are coupled to an electrical power supply and coupled together at the second end via an impedance, the control unit being arranged to detect when the body is pressed by detecting an increase in electrical current passing through the contact strips or a reduction in the voltage across the contact strips corresponding to the contact strips coming into electrical contact between their first and second ends.
The control unit may be coupled to the elongate light source and arranged to change the illumination of the body between a first state and a second state when a press of the body is detected.
The control unit may further comprise a reset input, the control unit being arranged to change the illumination of the body from the second state to the first state when a reset signal is received.
The control unit may be coupled to an external audible or visible alarm and is arranged to trigger the audible or visible alarm when a press of the body is detected.
The control unit may be arranged to change the illumination of the body to a third state if the control unit detects an open circuit fault across the contact strips. The third state of the illumination of the body may correspond to the elongate light source being turned off.
An embodiment of the invention will now be described by way of example only with reference to the following figures in which:

Figure 1 shows a perspective view of a switch in accordance with the GB-2440594-A ;
Figure 2 shows a perspective view of an alarm switch in accordance with an embodiment of the present invention;
Figure 3 shows a partially disassembled view of the alarm switch of figure 2;
Figure 4 shows an enlarged view of the activating strip of the alarm switch of figure 2;
Figures 5A and 5B show exploded views of the activating strip of figure 4 illustrating a connector for coupling to the contact strips of the activating strip;
Figure 6 shows an enlarged, exploded view of the channel of the alarm switch of figure 2;
Figure 7 shows an enlarged view of a base support for channel corners as illustrated in the partially disassembled view of figure 3;
Figures 8 and 9 respectively show enlarged views of the internal and external channel corners of the alarm switch of figure 2;
Figure 10 shows an enlarged view of the channel end cap of the alarm switch of figure 2;
Figure 11 shows an enlarged view of the lighting strip as illustrated in the partially disassembled view of figure 3; and
Figure 12 shows a system diagram for the alarm switch of figure 2.

Referring first to figure 2, this shows a perspective view of an alarm switch in accordance with an embodiment of the present invention. The alarm switch comprises a channel 30 and an activating strip 32. The channel 30 is formed from first and second channel portions, as illustrated in figure 6 and described in greater detail below. The channel 30 is arranged to support and retain the activating strip 32. The channel 30 generally comprises a back portion to be secured to a wall and retaining tabs arranged to surround and secure the activating strip. The channel 3 may be formed from any suitable material providing the necessary strength to support the activating strip 32 and capable of being formed in the required shape, for instance a metallic or rigid plastics material.
The activating strip 32 comprises a continuous strip switch formed from a deformable tubular body containing first and second elongate electrical contact strips, as will be described in greater detail below in connection with figures 5A and 5B. The activating strip 32 is arranged within the channel 30 such that at least a portion of the activating strip 32 is exposed within the channel 30 and can be hit or otherwise manipulated by a user in order to cause the contact strips to come into contact to activate the switch. The activating strip 32 may be recessed within the channel 30, flush with the sides of the channel or raised up above the sides of the channel in order to vary the ease with which the activating strip 32 may be hit by a user according to the required sensitivity of the application of the alarm. The alarm switch of figure 2 shows the activating strip 32 slightly recessed within the channel 30 so as to ensure that knocks from hard objects do not activate the switch. For instance, the alarm switch of figure 2 may be particularly useful in hospitals where the switch as the recessed activating strip 32 will be less susceptible to being inadvertently triggered when the switch is knocked by a trolley. It will be appreciated that the relative size and shape of the activating strip 32 and the channel 30 may vary.
The channel 30 is arranged to be secured to a wall or other solid object to support the activating strip 32, for instance at waist level running around a room. Figure 2 further illustrates internal and external corners 34, 36 respectively for securing the alarm strip to the corners of a room. The corner pieces are described in greater detail below in connection with figures 7 to 9. Figure 2 further illustrates end caps 38 for terminating the alarm strip at the appropriate point along a wall. The end caps 38 are described in greater detail below in connection with figure 10.
Referring now to figure 3, this illustrates a partially disassembled view of the alarm switch of figure 2. The corners 34, 36 and end caps 38 have been removed. Further more part of the channel 30 has been removed and one section of the activating strip 32 has been removed. It can be seen that the activating strip 32 comprises a generally flattened elongate structure having tab portions 40 arranged to be received within grooves within the channel 30 in order to secure the activating strip in position. Each section of activating strip 32 is terminated with a connector block 42 (illustrated in the exploded views of figure 5A and 5B) arranged to make electrical connection to the contact strips within the activating strip 32. The connector blocks 42 are coupled to wires 44 to connect together adjacent connector blocks 42 (and hence adjacent sections of activating strip 32) or to couple the activating strips of an alarm switch to the external control system (illustrated in figure 12).
The removed corner pieces 34, 36 allow a corner base support 46 to be seen. The corner base supports 46 are common to the internal and external corners 34, 36 (the base supports 46 being rotated through 180° between each type of corner) and couple together the sections of channel 30.
In accordance with the present invention the alarm switch further comprises a lighting strip 48 extending at least partially along the length of the switch. The present inventor has identified a requirement for users to receive an immediate indication that pressing the alarm switch has been successful before assistance arrives and regardless of where along the length of the alarm switch the activating strip is manipulated. In order to provide such an indication, the activating strip 32 is formed from a transparent or a translucent material and the lighting strip 48 is positioned underneath the activating strip 32 along at least part of its length. In one embodiment the lighting strip 48 comprises a flexible transparent rubber or plastic tube comprising an array of LEDs. Alternative light sources, for instance fibre optics, will be readily apparent to the skilled person. Furthermore, the light source may be coupled to the channel or activating strip using any conventional manufacturing techniques.
The lighting strip 48 is arranged to be received within a groove formed in channel 30 and positioned, once assembled, centrally underneath the activating strip 32. In one embodiment the lighting strip 48 may be positioned underneath the contact strips within the activating strip 32 such that the activating strip 32 glows with a diffuse light rather than the lighting strip shining directly through the activating strip 32. However, alternatively or additionally, similar lighting strips 48 may be provided within grooves either side of the midpoint of the activating strip. It will be appreciated that the profile of such additional lighting strips may vary to fit the grooves of the channel 30. In further embodiments of the invention the lighting strip may be positioned within the activating strip 32 Figure 3 further illustrates a lighting strip connector 50 and wires 52 for coupling the lighting strip 48 to the external control system. The lighting strip 48 is shown separately in figure 11.
Figure 4 shows a section of activating strip 32 separated from the channel 30 and fitted with connector blocks 42. It can be clearly seen in figure 4 that the activating strip is generally flat on a reverse side (arranged in use to face into the channel 30) and has a raised central portion 54 running along the front side of the activating strip 32. The raised central portion 54 is arranged to be seated between the retaining tabs of the channel 30, either flush with the tabs, protruding from the tabs or recessed within the channel 30. The activating strip 32 is formed from first and second layers 56, 58 of a rubber or plastics material forming the front and reverse sides respectively. The activating strip 32 is assembled by laminating the contact strips to the first and second layers 56, 58 and welding the layers together along the edges. The construction of the activating strip 32 is generally the same as for the tubular body 4 of the switch of figure 1 and is described in greater detail in GB-2440594-A .
Figure 4 further illustrates the connectors 42 fitted into the ends of the activating strip 32 within the cavity between the first and second layers 56, 58 to make electrical contact to the contact strips. The connectors 42 comprise shaped plastic plugs having tapered insert portion arranged to fit into the activating strip 32 and a flange portion 60 to prevent over insertion. The plastic plugs serve to support wires 44 and the electrical connector tabs.
Figure 5A illustrates a partially exposed view of a connector 42 fitted into an end of an activating strip 32 viewed generally from the front of the activating strip. The front layer 56 of the activating strip 32 has been removed. Also the insert portion of the connector 42 has been removed. A first metal contact strip 62 can be seen laminated to the second, back layer 58 of the activating strip 32. Wires 44 pass through the connector 42 and terminate at sprung electrical contacts 64. A first electrical contact 64 is held by the insert portion against contact strip 62.
Figure 5B illustrates a partially exposed view of a connector 42 fitted into an end of an activating strip 32 viewed generally from the reverse of the activating strip. The reverse layer 58 of the activating strip 32 has been removed. The insert portion 66 of the connector 42 can be seen. A second metal contact strip 68 can be seen laminated to the first, front layer 56 of the activating strip 32. The insert portion 66 is arranged to hold the electrical contacts 64 against the metal contact strips 62, 68 such that one wire connects to a first contact strip and the other wire connects to a second contact strip. The connectors 42 are arranged to automatically make the appropriate connections to the contact strips 62, 68 by inserting the insert portion 66 into the cavity between the layers 56, 58 of the activating strip 32 without requiring any further involvement from the installer.
Referring now to figure 6, this illustrates an exploded view of the channel 30 with the activating strip 32 and the lighting strip 48 removed. The channel 30 is formed from first and second channel portions 70, 72. Channel portion 70 comprises a back portion 74 arranged to be secured to a wall with retaining screws 76 and a first fixed retaining tab 78 arranged to pass over tab 40 of the activating strip 32. The second channel portion 72 comprises a removable retaining tab arranged to couple to the first channel portion 70 after the activating strip 32 has been inserted to secure the other tab 40 of the activating strip 32.
The second channel portion 72 is secured to the first channel portion 70 by engage flexible tab 75 into groove 76 and folding the second channel portion over the first channel portion 70 (and the activating strip 32) until locking tab 78 engages locking groove 80. Flexible tab 75 is coupled to the rest of the second channel portion 72 by a flexible web 82.
The back portion 74 of the first channel portion 70 comprises a central groove 84 running along the length of the channel 30 to receive the lighting strip 48. Side grooves 86 may alternatively or additionally be arranged to receive similar lighting strips. It will be appreciated that in alternative embodiments of the present invention light sources extending along the length of the alarm strip may be directly coupled to the channel, or may be secured in other ways beyond a flexible plastic encased lighting strip. LEDs may typically be used to illuminate the activating strip, however other suitable light sources will be well known to the skilled person. The central groove 84 further comprises a wire port 88 arranged to allow the activating strip connector wires 44 and the lighting strip connector wires 52 to exit the alarm strip through the back of the channel 30 for connection to the external control system.
In an alternative embodiment of the present invention the sides of groove 84 may be raised up higher than the back edge of the retaining tabs such that the activating strip 32 is forced outwards along its central portion to protrude from the channel. Additionally, or alternatively, blocks may be positioned within the groove 84 to force the back layer 58 of the activating strip 32 outwards to reduce the gap between the metal contact strips 62, 68 within the activating strip 32 to increase the sensitivity of the alarm strip by reducing the pressure that needs to be applied to the activating strip to bring the metal contact strips 62, 68 into contact to activate the switch.
Figure 7 illustrates an enlarged view of the corner base support 46. As noted above, the same base support is used for both internal and external corners. The base support 46 comprises a one piece moulded plastic block arranged to be secured to a wall with screws 90. Extending from either side of the corner base support 46 are tabs 92 arranged to be received in the side grooves 86 of the channel 30 to ensure that the channel is correctly aligned with the corner. The tabs 92 need not securely lock to the channel side grooves 86 because the channel is separately secured to the wall as noted above in connection with figure 6. A central portion of both sides of the base corner support 46 comprises a recessed channel 94 arranged to receive the lighting strip 48.
Figures 8 and 9 illustrate enlarged views of the internal and external corner pieces 34, 36 respectively. The corner pieces 34, 36 comprise one piece moulded plastics components arranged to fit over the base corner supports 46 and to be secured to the wall by fixing screws 96 passing through corresponding holes 98 in the base supports 46. Plugs 100 are arranged to cover fixing screws 96 to improve the appearance of the alarm switch. Figure 10 illustrates an end cap 38 arranged to fit over an end of a channel 30 and to be secured to the channel and the wall by a fixing screw 102 passing through a hole in the end of the channel 30 into the wall and covered by plug 104.
Figure 11 illustrates a lighting strip 48 in accordance with an embodiment of the present invention. The lighting strip 48 generally comprises an array of LEDs encased in an extruded tube of transparent or translucent material arranged to fit within groove 84. The LEDs may be evenly spaced apart along the length of the lighting strip 48 or they may be concentrated in portions of the strip. The strip 48 may be flexible along its entire length or it may comprise flexible hinge portions 106 arranged to match up with the corners of the alarm switch and to pass through the recessed channel 94 within the base supports 46.
Referring now to figure 12 this illustrates a system diagram for a control system for the alarm switch of figure 2. The channel 30 is schematically represented as box 108 containing the contact strip formed from metal strips 62, 28 and the LED lighting strip 48. The lighting strip 48 may comprise a number of LEDs arranged in series. Alternatively there may be multiple groups of serial LEDs arranged in parallel for redundancy in the event of the failure of an LED. Alternatively, the LEDs may be connected in parallel. The alarm switch 108 is coupled to an external control unit 110 at a first end, with the metal contact strips connected to an electronic control system 112 within the control unit 110 by wires 44. The other end of the contact strips 62, 68 are coupled together via an end of line resistor 114. The electronic control is arranged to monitor current passing through the end of line resistor 114 or the voltage between the contact strips firstly to confirm that the contact strips are connected correctly and that there is no break in the system, and secondly to detect an increase in current (or a reduction in voltage) due to the activating strip 32 being pressed to bring the contact strips 62, 68 into contact with one another and shorting out the end of line resistor 114.
The alarm system further comprises a power supply unit 116 arranged to supply power to the control unit 110. The power supply unit 116 may in turn be connected to a mains electricity circuit through a conventional plug. The power supply to the electronic control system 112 passes through a protection circuit 118 (for instance a fuse). The protection circuit 118 is arranged to prevent damage to the electronic control system 112 in the event of a spike in the power supply. Furthermore, the protection circuit 118 may be arranged to block the power supply in the event of a reversed polarity supply being connected to the control unit 110. Similarly, the power supply to the LED lighting strip 48 is protected by the protection circuit 118. Power supplied to the lighting strip 48 is controlled by a power switch 120 operated by the electronic control system 112.
In the event that the electronic control system 112 detects that the activating strip 32 has been pressed, the switch 120 is closed causing the lighting strip 48 to be illuminated to provide an immediate indication to the user that the alarm switch is operating. In an alternative embodiment, so long as the electronic control system 112 does not detect an open circuit fault between the metal contact strips 62, 68 then the LED lighting strip 48 may be continuously illuminated to indicate to users that the switch is operational. If the electronic control system 112 then detects that the activating strip 32 has been pushed then the lighting strip 48 may be arranged to flash repetitively to indicate to the user that the press of the activating strip has been detected.
Furthermore, the electronic control system 112 passes a control system to an external alarm system 122 (which may be part of a general building alarm system). The external alarm system 122 triggers the appropriate action, for instance an audible or visible alarm, or summoning assistance. An operator of the external alarm system 122 may send a reset signal to the electronic control system 112 causing the power switch 120 to be opened to turn off the lighting strip 48. Furthermore, the control unit 110 may comprise a local reset button.
The control unit 110 may further comprise one or more status LEDs to indicate whether the alarm switch is operating correctly. For instance if the electronic control system detects an open circuit for the metal contact strips 62, 68 this indicates that the alarm switch is not operative and a warning LED is illuminated. When power is first supplied to the electronic control system 112 when the control unit 110 is connected to the mains electricity supply the or each status LED on the control unit may be initially turned to red. The electronic control system 112 may then perform a continuity check upon the metal contact strips 62, 68 and the status LEDs changed to green if the circuit is closed or remain red if an open circuit fault is detected. If the circuit is closed then the LED lighting strip is switched on to confirm to the users that the system is active and ready to be used. The alarm switch may be tested by striking the activating strip, and then reset using the local or remote reset function. If at any point an open circuit fault between the contact strips 62, 68 (or an internal fault within the control unit 110) the lighting strip 48 is switched off and the status LEDs revert to red. The fault mode may be confirmed to work correctly by removing the end of line resistor (which should turn off the lighting strip and set the status LEDs to red until it is replaced). As a further option, the electronic control system 112 may be arranged to detect whether the lighting strip 48 is operating correctly. If a fault is detected a warning LED may be illuminated or the switch deactivated.
An advantage of embodiments of the present invention is that the LED lighting strip, or other light sources distributed along the length of the activating strip, passes light through the activating strip indicating to a user that the alarm switch is operational or activated. Depending upon the light transmissive properties of the activating strip materials, and the position of the light sources relative to the metal contact strips, the light emitted may be a diffuse glow or a bright, clear source of light direct from the LEDs. In certain embodiments of the invention the light sources may be positioned within the activating strip, either embedded in the first or second layers or a separated component welded between the layers or trapped in position. Advantageously, the portion of the alarm switch that is illuminated is the same portion of the switch which must be pressed by a user to trigger an alarm making it easier for a user to locate the switch, to identify that the switch is operational, to identify how to operate the switch and to identify that the press of the activating switch has been detected.
Alarm switches in accordance with embodiments of the present invention may be 25m long or more. The distributed light sources along the activating strip allow for clear illumination along the whole of the length of the switch. It is the distribution of the light sources along the length of the activating strip which allows for this clear illumination.
In alternative embodiments of the invention the light sources along the activating strip may be arranged to illuminate different colours, flash at different rates or change colour according to whether a fault condition or switch activation has been detected.
The present invention may be particularly beneficial to protect employees in situations where they may be subject to physical attack, for instance in a police station or a hospital. More generally, it may be beneficial wherever there is a need to summon assistance. For instance, the alarm switch may be used to replace or supplement conventional pull cord alarms in disabled toilets. The alarm switch may be positioned wherever required upon a wall, or at multiple levels. Advantageously the alarm switch is less prone to interference or mistaken activation than a pull cord alarm.
As discussed above, the sensitivity of the switch to pressing may be adjusted by changing the degree to which the activating strip protrudes from the channel or varying the profile of the activating strip to adjust the gap between the metal contact strips. In one embodiment a low profile activating strip may be provided to reduce the incidence of accidental pressing by an object striking the channel. However the sensitivity may be kept high by inserting blocks behind the activating strip to reduce the contact gap. Alternatively, in situations where it is essential that a press is quickly detected the activating strip may be arranged to protrude from the channel (by adjusting the shape of the channel or the activating strip or both) to ensure that it is easy to press.
Automatic illumination or flashing of the switch in response to a press may in some situations serve to warn off an attacker. Also, the continuous illumination of the switch before activation may have a deterrent value.
The channel may be formed from a polished or anodised aluminium material. The end caps and corner pieces may be formed from matching or contrasting coloured plastics.
Optionally the plastic components of the alarm switch may be impregnated with an anti-microbial compound and the channel lacquered with an anti-microbial compound to protect against germ build up, which may be of particular benefit in hospital applications. Furthermore, the alarm switch presents a smooth exterior profile allowing for easy cleaning.
It will be appreciated that the form and dimensions of the alarm switch, and the component materials, may vary. In one exemplary embodiment the channel may be approximately 60mm wide and 14mm deep, supplied in standard 2000mm lengths and formed from aluminium. In another embodiment the channel may be 88mm wide and 20mm deep. The activation strip may be 54mm wide, 9mm deep and provide a 34mm impact zone arranged to be exposed between the channel retaining tabs. The LED light strip may be 8mm wide by 2.5mm deep and provide 60 LEDs per metre.
The activating strip of the present invention will now be described in greater detail. The first electrical contact strip and the second electrical contact strip can each be fastened to the substantially tubular body along only a portion of their lengths. Preferably, the first electrical contact strip and second electrical contact strip are fastened to the substantially tubular body along at least 50% of their length, more preferably at least 75% of their length, especially preferably at least 90% of their length. Preferably, the first electrical contact strip and second electrical contact strip are each welded to the substantially tubular body along substantially their entire length.
The activating strip comprises a deformed stated when pressed in which the contact strips touch one another to close the circuit and a non-deformed state in which they are spaced apart. Preferably the contact strips are non-apical, that is they do not form an apex facing one another, rather they are planar or curved. Preferably, in the non-deformed state the first non-apical electrical contact strip and the second non-apical electrical contact strip are spaced apart by 5mm or more. The closer together the first and second non-apical electrical contact strips are the more likely the switch is to be activated accidentally. Preferably, the distance between the first non-apical electrical contact strip and the second non-apical electrical contact strip is not more than 7mm. The further apart the first and second non-apical electrical contact strips are the greater the distance it is required to activate the switch. However, as would be understood, the preferred maximum distance between the first and second non-apical electrical contact strips can vary depending on the application in which the switch is to be used. The first non-apical electrical contact strip and the second non-apical electrical contact strip may be substantially diametrically disposed in the substantially tubular body.
The first, face layer of the activating switch could be made from a material having different mechanical properties to the material of the second, reverse layer. However, it may be that both the first and second layers are made from a resiliently deformable material. At least one the first and second layers needs be made from a resiliently deformable material. This can aid assembly of the substantially tubular body. For instance, at least one of the first and second layers can be made from a resiliently deformable material such as any of vinyl films, polyurethane, polypropylene coated fabric, polyethylene and thermoplastic rubber. Preferably, one of the first and second layers is made from a polyvinyl chloride (PVC) material, for example a PVC Nitrile blend, particularly a PVC Nitrile blend suitable for dynamic gasket applications, such as DNC80. The other of the first and second layers can also be made from a non-deformable material such as a stainless steel, non-flexible PVC material or other suitable polymeric materials, although commonly will be formed also from a flexible PVC material.
Preferably, the first and second layers are welded to each other. This provides for a strong bond between the first and second layers. It also provides for a flexible bond between the first and second layers and therefore improves the reliability and performance of the switch.
Preferably, the first non-apical electrical contact strip and the second non-apical electrical contact strip are made from a metallic material. More preferably the first non-apical electrical contact strip and the second non-apical electrical contact strip are made from copper. Electrical contact strips made from metallic materials, and in particular made from copper, provide better electrical conduction compared to non-metallic electrically conductive materials. Further, there is much less voltage depletion using metallic contact strips in contrast to other non-metallic electrically conductive materials. Accordingly, the switch of the present invention can be manufactured to much greater lengths compared to switches with non-metallic electrically conductive contact strips.
The first non-apical electrical contact strip and the second non-apical electrical contact strip can be secured to the internal walls of the substantially tubular body by mechanical fastenings. The first non-apical electrical contact strip and the second non-apical electrical contact strip can be secured to the internal walls of the substantially tubular body by an adhesive.
Preferably, the first non-apical electrical contact strip and the second non-apical electrical contact strip are welded to the substantially tubular body. Preferably, each of the first non-apical electrical contact strip and the second non-apical electrical contact strip comprises a layer of electrically conductive material laminated to a welding material layer, wherein the welding material layer is welded to the substantially tubular body. Preferably, the layer of electrically conductive material is a metallic material. Preferably, the metallic material is copper.
There are many suitable materials which can be used as the welding material. Preferably, such materials have shrinkage properties similar to that of the metallic material. In many circumstances it can be preferred that the stiffness of the welding material is less than that of the metallic material. In some circumstances it can be preferred that stiffness of the welding material is greater than that of the metallic layer. Preferably, the welding material has a UL rating of approximately 105°C. Preferably, the welding material is a polyester material. More preferably, the welding material is polyethylene terephthalate (PET).
Welding the first non-apical electrical contact strip and the second non-apical electrical contact strip to the substantially tubular body by the welding material layer provides a firm bond between the layer of electrically conductive material and the substantially tubular body. This welded bond is advantageous over other forms of fastening, such as using mechanical grippers, because it provides for a much more secure fixing. Accordingly, the switch feels much more solid and responsive to the user. It is also advantageous because the bond between the layer of electrically conductive material and the substantially tubular body is flexible. This provides for the deformation of the substantially tubular body without breaking the bond between the layer of electrically conductive material and the substantially tubular body, and therefore increases the reliability and durability of the switch.
Preferably, the thickness of the welding material layer is at least 2 microns, more preferably at least 3 microns, for example at least 4 microns. Preferably, the thickness of the welding material layer is not more than 600 microns, more preferably not more than 500 microns. The thickness of the welding material layer affects the quality of the bond between the layer of electrically conductive material and the substantially tubular body. The preferred thickness of the welding material layer can depend on the thickness of the layer of electrically conductive material to which it is laminated. Preferably, the ratio of the thickness of the welding material layer to the thickness of the layer of electrically conductive material is not more than 3, more preferably not more than 2, especially preferably not more than 1. As will be understood, the thickness of the welding material depends on the application in which the switch is to be used.
Further modifications to and applications of the present invention will be readily apparent to the appropriately skilled person from the teaching herein without departing from the scope of the appended claims.

Claims

A switch comprising:
an activating strip (32) comprising a tubular body which is resiliently deformable and contains first an second electrical contact strips (62,68) arranged so that the contact strips (62,68) are brought into contact to close the switch when the tubular body is deformed;

an elongate light source (48) coupled to the activating strip (32) along at least part of its length; and

an elongate channel (30) arranged to support the activating strip (32) and the elongate light source (48) such that the channel (30) partially surrounds the activating strip (32) leaving a portion of the activating strip (32) exposed within an open part of the channel (30) allowing the activating strip (32) to be hit or otherwise manipulated to deform the activating strip (32) within the channel (30);

characterised in that the elongate light source (48) is arranged to shine through at least part of the tubular body to illuminate at least part of the activating strip (32) and the elongate light source (48) is positioned between the channel (30) and the activating strip (32) such that light from the elongate light source (48) can pass through the activating strip (32) and through the open part of the channel (30), the activating strip (32) being formed from a transparent or a translucent material.
A switch according to claim 1, wherein the first and second electrical contact strips (62,68) extend along at least part of the tubular body.
A switch according to claim 1 or claim 2, wherein:
the first and second electrical contact strips (62,68) are secured to first and second internal walls of the tubular body so that the electrical contact strips (62,68) are in a spaced apart relationship when the tubular body is in a non-deformed state.
A switch according to any preceding claim, wherein the elongate light source (48) comprises an array of discrete light sources.
A switch according to claim 1, wherein the first and second electrical contact strips (62,68) are substantially diametrically disposed in the tubular body.
A switch according to claim 5, wherein the first and second contact strips (62,68) are aligned with the open part of the channel (30) and the elongate light source (48) is located underneath the contact strips (62,68).
An alarm system comprising:
a switch according to any one of the preceding claims; and

a control unit (110) coupled to the switch;

wherein the control unit (110) is arranged to detect when the activating strip (32) is pressed and to control the elongate light source (48) to adjust the illumination of the activating strip (32) according to whether a press of the activating strip (32) is detected.
An alarm system according to claim 7, wherein the electrical contact strips (62,68) are coupled at a first end to the control unit (110) such that the contact strips (62,68) are coupled to an electrical power supply (116) and coupled together at the second end via an impedance (114), the control unit (110) being arranged to detect when the activating strip (32) is pressed by detecting an increase in electrical current passing through the contact strips (62,68) or a reduction in the voltage across the contact strips (62,68) corresponding to the contact strips (62,68) coming into electrical contact between their first and second ends.
An alarm system according to claim 7 or claim 8, wherein the control unit (110) is coupled to the elongate light source (48) and arranged to change the illumination of the activating strip (32) between a first state and a second state when a press of the activating strip (32) is detected.
An alarm system according to claim 9, wherein the control unit (110) further comprises a reset input, the control unit being arranged to change the illumination of the activating strip (32) from the second state to the first state when a reset signal is received.
An alarm system according to any one of claims 7 to 10, wherein the control unit (110) is coupled to an external audible or visible alarm (122) and is arranged to trigger the audible or visible alarm when a press of the activating strip (32) is detected.
An alarm system according to any one of claims 8 to 11, wherein the control unit (110) is arranged to change the illumination of the activating strip (32) to a third state if the control unit (110) detects an open circuit fault across the contact strips, wherein the third state of the illumination of the activating strip (32) preferably corresponds to the elongate light source (48) being turned off.