LIGHTING DEVICE

Abstract: A lighting device (10) for use in security and observation lighting systems is described. The device (10) includes a component support surface (12) disposed within a box-shaped polycarbonate housing (14). Removably mounted on the support surface (12) are a fluorescent tube lamp (16), a starter device (18) and a removable and interchangeable control module (20). Various different and interchangeable control modules (20) may be mounted on the support surface (12). When a module (20) is mounted thereon, the lamp (16) is energised in accordance with the function determined by the specific control module (20). Embodiments of the invention are described.

Description: LIGHTING DEVICE The present invention relates to a lighting device and particularly, but not exclusively, to a lighting device for use in security and observation lighting systems. Existing lighting devices for security and observation lighting systems provide a various number of separate modes of operation of these lighting devices. Some of these devices, commonly referred to as passive infra red detectors, switch on when the device senses movement of a heat source in a detection field of the device. Other devices are light sensitive and are arranged to switch on at dusk and switch off at, for example, dawn. When more than one of these modes of operation of the lighting devices are to be provided, separate lighting devices must be used, each of these devices providing an individual function. This can be relatively expensive if a number of such lighting devices have to be purchased. A further disadvantage of such lighting is that the security function of the lighting may be obvious. This can result in vandalism of the device, it is desirable to provide a single lighting device whose security purpose is not immediately obvious and which can provide more than one mode of operation. It is an object of the present invention to provide a lighting device which obviates, or mitigates, at least one of the aforementioned problems. According to the present invention there is provided a lighting device comprising a light source, at least one control device removably coupled to said light source and adapted to be coupled to a power supply, and a sensor coupled to said control device, whereby, in use, said control device is arranged to receive a signal from said sensor for energising said light source. Preferably there is provided a plurality of interchangable control modules mountable in the lighting device to enable provision of different modes of operation for said lighting device. Preferably also said lighting device comprises a housing and a component support member securable therein by means of at least one spring-loaded locking member which is adapted to engage said support member to hold said member in piace within said housing. Preferably also there is provided a cover which is adapted to be connected to said housing in order to provide protection for the components mounted on said support member. The housing is provided with a plurality of upstanding posts, located internally around the periphery of the housing, said posts being arranged in such a manner that when said cover portion is received in a tight fitting relationship between the posts and the housing, the cover is retained in" a position where the cover is spaced from the support member and its electrical components carried thereon. Conveniently also said housing and cover are made of polycarbonate. An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings in which:- Fig. 1 is a perspective and partly broken away view of a lighting device in accordance with an embodiment of the present invention; Fig. 2 is an elevational view of a circuit bridging element for use with the lighting device shown in Fig. 1; Fig. 3 is a perspective view of the base of the housing of the lighting device shown in Fig. 1 drawn to a smaller scale; Fig. 4 is a perspective view of an alternative cover which may be attached to the housing of the device shown in Fig. 1, and Fig. 5 is a perspective and partly broken away view of a second embodiment of a lighting device in accordance with the present invention. Reference is first made to Fig. 1 of the drawings which shows a lighting device generally indicated by reference numeral 10. The lighting device 10 comprises a component support surface 12 disposed within a generally square two piece polycarbonate housing 14 having upstanding peripheral side walls 15. Removably mounted on the support surface 12 are a fluorescent tube lamp 16 and a starter device 18. The lamp 16, starter 18 and a control module 20 can all be simply removed from surface 12 for maintenance or replacement. The control module 20 is a generally box-shaped control device containing the electrical and/or electronic circuitry necessary for operation in its predetermined mode. The module 20 has a number of electrical contacts and a locating pin which are not shown in the interest of clarity. The contacts and locating pin are received in a corresponding socket in the support surface. The control module 20 may be simply plugged into- the socket and held in place on support surface 12 by clips 24 (only one of which is shown) . The control module 20 may then be releasably fixed in place in support surface 12 by a locking pin (not shown) . Different control modules 20 may be removably coupled to support surface.12, each module providing a different mode of operation of the lighting device 10. The control module 20 shown in Fig. 1 acts as a passive infra-red sensor. The control module 20 comprises a multi-facetted lens 28 through which the control module 20 detects movement within a distance, for example, of 15 metres from the lighting device 10. The detection zone of the control module is the emission field of an IR transmitter (not shown) disposed substantially at the centre of lens 28. The emission field of the IR signals has a solid angle of 90° , the centre axis of which is at the position of the IR transmitter. Any movement and associated body heat of a person within this detection zone causes the control module 20 to deliver power to the lighting circuit. A timing device (not shown) causes the lamp 16 to switch off a predetermined time after the last detection of movement in the detection zone. As best shown in Figs. 1 and 3, two spring-loaded locking pins 29 are mounted on housing 14. When support surface 12 is located within housing 14 and forced towards the base 14, the locking pins 29 extend through corresponding slots 30 in support surface 12, as best shown in Fig. 1. Elongated heads of the locking pins 29 are rotatable through 90° into the position shown in Fig. 1, and in this position the surface 12 is firmly but resiliently retained within housing 14. The housing 14 also has an integral cable entry element 32 having a cable entry hole 34 through which a mains cable can be passed in order that power may be supplied to the lighting device 10. The cable (not shown) passes through cable entry hole 34 and passes beneath support surface 12. various electrical control elements and wiring connections (not shown) are located beneath surface 12. The support surface 12 acts as a protective enclosure for these components. Six upstanding L-shaped posts 36 are mounted around the internal periphery of upstanding side walls 15 of housing 14. A generally square polycarbonate cover portion 38 (best shown in Fig. 1) is attachable to housing 14 to cover surface 12 and provides protection for the components mounted thereon. Walls 40 of cover portion 38 are received in a tight-fitting relationship (friction fit) between the posts 36 and upstanding walls 15 of base portion 14. The cover portion 38 does not contact any of the components mounted upon support surface 12 and thus provides protection of these components. An alternative cover portion 41 is shown in Fig. 4, this cover portion 41 includes a translucent detachable screen 42. An IR transparent window 44 is provided in cover portion 41, cover portion 38 also has such a window, however, this is not shown in Fig. 1. The window 44 allows the infra-red sensor of control module 20 to detect movement in the detection field by allowing control module 20 to emit infra-red signals to -.=r ody heat and movement thereof. The control module is designed so that it will not operate in daylight conditions using a standard photocell circuit to detect ambient light levels. When other control modules are mounted on surface 12, as will be described, the window 44 may be replaced by a push button or simply covered by a decorative plastic layer. For this purpose, window 44 can be snap-fitted into cover 38 to allow simple removal and replacement. The passive IR module 20 as described in the foregoing embodiment can be selectively replaced by alternative control modules which can be simply plugged into socket 22, to change the mode of operation of the lighting device 10. A second type of light sensitive control module which may be plugged into socket 22 causes lamp 16 to switch on at dusk and switch off at dawn. The control module comprises a light dependent resistor which limits the switching of an A.C. mains circuit in response to pre-set ambient levels of light. A third type of control module which may be plugged into socket 22 provides a simple push button control. This control module comprises an electrical circuit which has a remotely controlled low voltage reed switch which controls a timed A.C. mains circuit. A non-latching push-button mounted on cover 38 in the place of window 44 presents a small magnet to the reed switch enabling the fixed time circuit. A continuously powered neon indicator provides a visual indication of the position of the push button which is extinguished during the fixed time period. The fourth type of control module which may be plugged into socket 22 causes lamp 16 to switch on at dark and switch off after a predetermined period of time . in this arrangement, the control module embodies a quartz time clock in order to monitor the time and to actuate switch-off at the desired time. in order to determine the selected night switch-off time the module is plugged into the unit 12 hours in advance of the desired switch-off time. Switch-on occurs at dusk under normal preset ambient light levels. When none of the four control modules hereinbefore described are plugged into socket 22, lamp 16 may be energised by utilising a circuit bridging element 45 (best shown in Fig. 2) This element 45 is located in terminals of the socket in a manner similar to that described for control module 20. With bridging element 45 in this position the lamp 16 is constantly energised. When not required, the bridging element 45 must be removed to allow a control module to be operatively mounted in the lighting device. The bridging element 45 may then be clipped to a side wall 15 of housing 14 by a clip (not shown in the interest of clarity. The bridging element 45 is necessary for enabling lamp 16 to be operated without a control module and reinstates the fitting for normal.mains ' control when the control module is removed from the fitting for replacement or repair. Reference is now made to Fig. 5 of the drawings which is a perspective and partly broken away view of a lighting device similar to that shown in Fig. 1 where like numerals refer to like parts with the suffix 'a' added. The device 10a consists of a component surface 12a disposed within a generally rectangular two piece housing 46. Mounted upon the component surface 12a are a fluorescent tube lamp 16a and two control modules 20a and 20b. Both control modules 20a and 20b provide alternative modes of operation of the device 10a. Control module 20a is an infra-red detector and operates as hereinbefore described causing the lamp 16a to switch on when the module 20a detects movement in its detection zone. Module 20b is a push button device similar to the third type of module hereinbefore described. When button 48 is depressed the lamp 16a is turned on for a period of time before automatically switching off under control of module 20b. The control module 20b provides a manual override for module 20a and includes a lamp (not shown) which illuminates when the button 48 is pressed to indicate that the manual override is in use. Various modifications may be made to the embodiment hereinbefore described without departing from the scope of the present invention. For example, the lighting device could be made in any suitable shape or size and in any suitable material such as metal or wood. An- alternative combination of control modules may be used to vary the modes of operation of the lighting device. For example, a combination of control modules could be used to produce a lighting unit which emits light from dusk to a predetermined switch off time and after that, switches on the light when movement is sensed in the detection field. The light could be coupled to an audible alarm which will be switched on when movement is sensed in the detection field. Alternatively, the lighting device could be coupled to a door bell so that the lamp is energised when the door bell is pressed. Fibre-optic cables could be used to couple the control modules and all control modules can be used to control the power supplied to up to 1500 watts of slaved or network lighting . in an alternative form of dusk to dawn module or dusk to predetermined time off module a lens associated with the module is not incorporated in the module itself, in this alternative arrangement, the lens which detects ambient light levels is located remotely from the module. The lens is interconnected in a light-shielded manner by a fibre optic cable which extends between the lens and the control module in order to transmit light from the lens to a light dependent resistor in the remote control module. The cover may be held in place on its housing by any suitable clip, fastener or locking arrangement which holds the cover portion in such a position that the modular components are protected in a substantially sealed condition. An advantage associated with the present invention is that a lighting device is provided whose mode of operation can be altered by simply plugging in any one of a number of selectively interchangeable control modules or combinations of said modules to permit a single lighting device to perform various functions with a high degree of adaptability at a relatively low cost. Other advantages include: each component of the device is easily accessible and can be simply removed and replaced for maintenance; the electrical contacts of the components are touch free and as a result the device is safe to handle, and the control modules are operatively mounted within the lighting device of the invention without the necessity of using tools. The control modules are disposed inside the cover and thus their security function is less obvious. The cover also tends to prevent accidental damage of the lighting device and reduces the temptation to vandalise the lighting device.

Claims: CLAIMS 1. A lighting device comprising a light source, at least one control device removably coupled to said light source and adapted to be coupled to a power supply, and a sensor coupled to said control device, whereby, in use, said control device is arranged to receive a signal from said sensor for energising said light source. 2. A lighting device as claimed in claim 1 wherein a plurality of interchangeable control modules are provided, each module being mountable in the lighting device to enable provision of a different mode of operation for said lighting device. 3. A lighting device as claimed in claim 1 or claim 2 wherein said device further comprises a housing and a component support member securable therein by means of at least one spring-loaded locking member which is adapted to engage said support member to hold said member in place within said housing. 4. A lighting device as claimed in claim 3 wherein there is provided a cover which is adapted to be connected to said housing in order to provide protection for the components mounted on said support member. 5. A lighting device as claimed in claim 4 wherein said housing is provided with a plurality of upstanding posts located internally around the periphery of the housing, said posts being arranged in such a manner that when said cover portion is received in a tight fitting relationship between the posts and the housing, the cover is retained in a position where the cover is spaced from the support member and its electrical components carried thereon. 6. A lighting device as claimed in claim 4 or claim 5 wherein said housing and cover are made of polycarbonate. 7. A lighting device as claimed in any preceding claim wherein said light source is a fluorescent light tube. 8. A lighting device as claimed in claim 7 wherein a starter for said fluorescent light tube is also removably mounted on said component support surface. 9. A lighting device as claimed in any of claims 2 to 6 wherein said sensor is an infra-red sensor for detecting movement within a detection zone of said sensor and for emitting a signal to the installed interchangeable control module when such movement is detected. 10. A lighting device as claimed in any of claims 2 to 6 wherein said sensor is a push button switch, the arrangement being such that when said switch is actuated, the installed interchangeable control module coupled to said switch receives a signal instructing the control module to energise the light source. 11. A lighting device as claimed in claim 9 or claim 10 wherein said sensor is integral with each of said interchangeable control modules. 12. A lighting device as claimed in any preceding claim wherein at least one of said interchangeable control odules includes timer means which switches the light sources on and off in accordance with a preset timing pattern. 13. A lighting device as claimed in any preceding claim wherein at least one of said interchangeable control modules includes ambient light detection means whereby said control module energises said light source when the ambient light falls below a predetermined level. 14 A lighting device as claimed in any preceding claim wherein two interchangeable control modules are coupled to a single light source, said control* modules having different functions and each being removably mounted in said device. 15. A lighting device as claimed in any preceding claim including a circuit bridging means for inserting in said device in place of an interchangeable control module to allow said light source to be energised from said power supply.

Inventors: COUGHTRIE JOHN GILLIES, COUGHTRIE, JOHN, GILLIES
Applicants: J & G COUGHTRIE LIMITED
Application year: 1989
Main classification: F21V23
IPC codes: F21V23