5 LIGHT ASSEMBLY FOR DOMESTIC AND INDUSTRIAL ENVIRONMENTS 10 COMMONWEALTH OF AUSTRALIA 15 PATENTS ACT 1990 20 'The invention is described in the following statement: 25 30 35 5 LIGHT ASSEMBLY FOR DOMESTIC AND [NDUSTRIAL ENVIRONMENTS 10 BACKGROUND The present invention relates to appliances and apparatuses and more particularly relates to lighting apparatuses for use in domestic, commercial and industrial environments. The invention further relates to a lighting apparatus 15 having improved heat dissipation and a capacity for flow through ventilation. The invention further relates to a light assembly which includes ventilation passages which enable heat to adopt a natural flow away from the light to reduce unwanted heating of light fittings. The invention further provides a light assembly which incorporates a dedicated exhaust on the back of a light fitting 20 to provide a toriodal heat dissipation chamber and means to enable cool air to flow through the centre of the fitting. The invention further relates to an alternative lighting assembly for industrial and domestic lighting which is environmentally friendly, increases heat flow away from the light using a simple geometry and construction. 25 PRIOR ART There are in existence a wide variety of lighting apparatuses used in a wide variety of applications. It is known in the art for lighting to be provided by 30 various light bulbs including the well known incandescent light bulb, the halogen bulb and the light emitting diode ( known as LED's) and metal halide lamp. An incandescent light bulb is made up of a thin, glass envelope. Inside the glass is a gas such as argon and/or nitrogen. At the center of the lamp is a 35 2 tungsten filament. Electricity heats this filament up to about 4,500 degrees F (2,500 degrees Celsius). The tungsten gets white hot at that temperature and emits visible light and generates intense heat in the fitting A normal light bulb in the process of radiating light, also radiates a huge 5 amount of infrared heat and in fact far more heat than light. Since the purpose of a light bulb is to generate light, the heat is wasted energy. A halogen lamp also uses a tungsten filament, but it is encased inside a much smaller quartz envelope. Because the envelope is so close to the filament, it would melt if it were made from glass. The gas inside the envelope is also 10 different since it consists of a halogen gas. Halogen gas combines with tungsten vapor. If the temperature is high enough, the halogen gas will combine with tungsten atoms as they evaporate and redeposit them on the filament. Because the quartz envelope is so close to the filament, it is extremely hot compared to a normal light bulb. 15 Halogen lights usually comprise a housing which supports a halogen lamp. The housing has an inner surface which allows reflection of light to the location at which the light is required. However, conventional halogen light fittings suffer from light losses due to back reflection away from the location light is required and light reabsorbed back into the quartz capsule.. Light housings are usually 20 parabolic as that shape usually provides optimal reflection of available lights. Another well known form of lighting is provided using light emitting diodes. Light emitting diodes (LED's) are used in a variety of applications. LED's do dozens of di fferent jobs and are found in all kinds of devices. 25 LEDs are tiny light bulbs that fit easily into an electrical circuit. But unlike ordinary incandescent bulbs, they don't have a filament that will burn out and they do not become as hot as incandescent lights. LED's are illuminated solely by the movement of electrons in a semiconductor material, and they last just as long as a standard transistor, and typically have a life of about 40000-100,000. 30 Light is a form of energy that can be released by an atom. It is made up of many 3 small particle-like packets that have energy and momentum but no mass. These particles, called photons, are the most basic units of light. Photons are released as a result of moving electrons. Electrons in different orbitals have different amounts of energy. 5 LED's were considered a decorative light source until recently. Technological advances have now allowed them to be used as a general light source, however, not all LED's are the sarne. By way of practical example, a form of LED lights is disclosed in US Patent No 68577561. 10 Many of the current LED fittings employ ribs which are used to dissipate heat energy . The ribs are usually spaced apart about the heat generating core of the fitting to allow them to present a large surface area which also provides a large total heat exchange surface. The more fins that are used the more heat is dissipated. Another currently known LED comprises a closed unit which 15 includes heat dissipating ribs and a concealed fan which drives the heat out of the light fitting. Fittings employing a large number of moving parts are undesirable as there exist more opportunities for failure. Heat naturally rises but the known LED lights are configured to force heat out of the fitting in a direction away from a direction of natural convection. Natural convection is up 20 but the known light fittings designs ignore this natural tendency and rely on a heat sink. In the known closed light heat can be trapped leading to unwanted heat levels which can shorten the life of the fitting. In a general sense the prior art teaches sealed LED's which includes concealed fins and those that use more exposed peripheral fins. Some of the current Led lights are vented to the side or 25 to the bottom of the light. An outer shell is connected to fins but this connection allows a heat bridge which enables heat from the fins to migrate to the outer body which results in a hot light. Another known LED fitting employs external fins which have a curved body which increases their surface area and therefore an increased heat dissipation area. If the heat of a light reaches 90 degrees the 30 light can ignite, Ideally the temperature of alight should be no more than 60 -80 degrees and preferably no more than 70 degrees. 4 One of the known Led lights comprises a generally parabolic housing which defines an internal space which houses the LED light centre. The housing has external ribs which are intended to receive heat generated from the light core. This housing is closed so considerable heat is trapped inside the housing 5 requiring conduction to the ribs. The closed LED's are prone to degrade from overheating so are not ideal for the purpose. A disadvantage of this type of light is that the heat is dissipated sideways and by conduction and only after it has been transmitted from the inner housing to the ribs. 10 Another of the known Led lights comprises an inner housing which defines ani internal space which houses the LED light centre. The housing has connected to it an array of external ribs which are intended to receive heat generated from the light core and transmitted to the housing. This housing is closed so considerable heat is trapped inside the housing requiring conduction to the ribs. 15 in this light the ribs are curved to provide a high surface area for heat exchange. Also the ribs define a generally parabolic outer surface terminating in a skirt. A space between the skirt and the light housing enables air to flow through the ribs to dissipate heat. A disadvantage of this type of light is that the heat is dissipated sideways and only after it has been transmitted from the inner 20 housing to the ribs. The closed LED's are prone to degrade from overheating so are not ideal for the purpose. Another of the known Led lights comprises an inner housing which defines an internal space which houses the LED light centre. The housing has connected to it an outer parabolic secondary housing. This creates an air gap between the 25 inner housing and outer housing. Concealed in the inner housing is a sealed fan which drives heat away form the heat generating centre in a down ward direction. A disadvantage of this light is that the direction of heat dissipation is downwards and the opposite to the natural tendency for heat to rise. This housing is arranged so considerable heat is trapped inside the housing requiring 30 conduction by the fan. A disadvantage of this type of light is that the heat is 5 dissipated down and laterally after it has been transmitted from the inner housing. Another of the known LED lights comprises an inner housing which defines an internal space which houses the LED light centre. The housing has, connected 5 to it an array of parabolic external ribs which are intended to receive and dissipate heat generated from the light core and transmitted to the ribs. This housing is closed so considerable heat is trapped inside the housing requiring conduction to the ribs. In this light the ribs terminate in a skirt which receives a detachable cover. The ribs in this light enables air to flow through the ribs to 10 dissipate heat. A disadvantage of this type of light is that the heat is dissipated sideways and only after it has been transmitted from the inner housing to the ribs. Air dissipated sideways retards cooling due to the sideways component. There is an ongoing need to provide improvements in lighting assemblies in 15 which heat is kept to a minimum and dissipated efficiently to avoid unwanted overheating of the light fitting. There is also a need to provide low cost, robust, longer life and minimal maintenance illumination of work and domestic environments with improved heat dissipation efficiency. 20 INVENTION The present invention provides a lighting apparatus having improved heat dissipation and a capacity for flow through ventilation. The invention further provides a light assembly which includes ventilation 25 passages which enable heat to adopt a natural flow away from the light to reduce unwanted heating of light fittings. The invention further provides a light assembly which incorporates a dedicated exhaust on the back of a light fitting to provide a toriodal heat dissipation chamber and means to enable cool air to flow through the centre of the fitting. using a simple geometry and construction. 30 6 The present invention provides a lighting apparatus for use in domestic or industrial environments which provides increased dissipation of heat. 5 In one broad form the present invention comprises: a light assembly for use in domestic and industrial environments, the assembly comprising: an inner housing which retains at least one LED, the inner housing including a first end having electrical connectors and second 10 end terminating in a skirt which retains a reflecting surface; the inner housing also including a flared region having an area extending beyond the area of the first end; an outer housing including a wall having an outer generally convex surface; a through passage between the inner housing and the outer housing; 15 at least one bridge member joining an inner wall of the outer housing to the skirt of the inner housing; the passage extending from the second end of the inner housing to the flared region of the inner housing there by forming a gap between the inner housing and the outer housing; wherein the location of the gap allows heat generated from the at least one LED to rise in the direction of 20 the first end of the inner housing to dissipate heat generated from said inner housing. According to one embodiment an outer surface of the outer housing includes a plurality of peripherally disposed ribs which provide a high surface area to 25 facilitate heat dissipation. According to one embodiment the outer housing comprises a parabolic shell and a plurality of bridging fins which extend inwardly from said inner surface of the outer housing and engage an outer surface of the inner housing. 30 Preferably the gap is peripheral and extends circumferentially about the flared region of the inner housing. The bridging members which join the inner surface 7 of the outer housing to the outer surface of the inner housing extend radially from the inner housing. Preferably the gap about the flared region of the inner housing is annular and allows the heat generated from the LED to be dissipated by adiabatic cooling.. 5 The inner housing further comprises a light reflective surface which is arranged to reflect all available light emitted from said at least one LED. In another broad form the present invention comprises: 10 a light assembly -for use in domestic and industrial environments, the assembly comprising: a housing having a first end including an electrical contact and a second end including a recess in which is disposed at least one LED; a skirt at least partially surrounding the housing and connected to the housing I5 via at least one radial rib; the skirt having a distal circumference defining an opening of a first radial extent and a proximal circumference defining an opening of a second radial extent; the proximal circumference defining an opening which receives said housing; 20 wherein a widest dimension of the housing is less that a widest dimension of tle opening defined by the proximal circumference, thereby forming an annular gap which receives air heated by the at least one LED. According to a preferred embodiment the widest dimension of the housing 25 occurs at an annular flared region such that a circumference of the flared region is concentric with the proximal circumference of the skirt. It is one object of the invention to meet the requirements for providing high levels of heat dispersion by adopting a ventilation geometry in the light to 30 Facilitate the natural ascending convection of heat. 8 It is a further object of the invention to provide a lighting assembly which uses efficient heat dispersion to minimise overheating of LED light fittings. It is a further object of the invention to provide a lighting assembly which uses 5 conductive materials and a geometry which increases efficiency of heat dissipation. It is a further objection of the invention to provide a lighting assembly which meets classification requirements for industrial and domestic areas. 10 The present invention provides an alternative to the known prior art and the shortcomings identified. The foregoing and other objects and advantages will appear from the description to follow. In the description reference is made to the accompanying representations, which forms a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may 15 be practiced. These embodiments will be described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the invention. In the accompanying illustrations, like reference characters designate the same or similar parts 20 throughout the several views. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims. BRIEF DESCRIPTION OF DRAWINGS 25 Figure 1 shows an elevation view of an LED light assembly according to a preferred embodiment. Figure 2 shows with corresponding numbering a long sectional elevation view 30 of the light assembly of figure 1 constructed in accordance with the present invention. 9 Figure 3 shows with corresponding numbering a cross sectional view of the LED light assembly of figure 1. 5 Figure 4 shows a top view of the LED light assembly of figure 1. DETAILED DESCRIPTION 10 The examples referred to herein are illustrative and are not to be regarded as limiting the scope of the invention. While various embodiments of the invention have been described herein, it will be appreciated that these are capable of modification, and therefore the disclosures herein are not to be construed as limiting of the precise details set forth, but to avail such changes and alterations 15 as fall within the purview of the description . Figure 1 shows an elevation view of an LED light assembly 1 according to a preferred embodiment. Figure 2 shows with corresponding numbering a cross sectional plan view of a light assembly 1 constructed in accordance with the 20 present invention Light assembly I comprises an inner housing 2 which retains at least one LED 3. Inner housing 2 includes a first end 4 having electrical connectors 5 and second end 6 terminating in a generally parabolic skirt 7 which retains a reflecting surface 8. Inner housing 2 also includes a flared region 9 having an edge 10 area extending beyond the area defined by the first end 4 of 25 housing 2. Assembly I further comprises a shell I I including a wall 12 having ai outer surface 13. Assembly I also comprises an array of peripheral ribs 14 which assist in the dissipation of heat generated by L) 3. Ribs 14 provide a high surface area to facilitate heat dissipation. Shell 11 terminates at a distal end 15 in an annular circumference 16 ( see figure 30 4) and at end 17 in an annular circumference 18. Between annular circumference 16 and annular circumference 18 is an annular gap 19. Between 10 wall 12 and skirt 7 is a through passage 20 which extends from distal end 15 to gap 1.9. Parabolic shell II is connected to skirt 7 via radial bridges or fins 14 which join inner surface 23 of wall 12 to outer surface 24 ( see figure 3) of skirt 7. Fins 14 transfer heat by conduction from skirt 7 to shell I I and then via gap 5 19 to the outside air. Through passage 20 allows heat generated from the LED 3 to rise in the direction of the first end of gap 19 to dissipate heat from housing 2. Heat generated form the LED is dissipated by both conduction via fins 14 and also via adiabatic cooling. 10 Shell 7 comprises a light reflective Surface 8 which is arranged to reflect available light emitted from the LED, Gap 19 is in apposition to flared region 9. Its proximity to edge 10 places ventilation gap 19 in a position for optimal heat dissipation as generated heat can rise vertically which is a natural passage for heated air. The widest dimension of the housing occurs at an annular flared 15 region such that a circumference of the flared region is concentric with the proximal circumference of the shell. From this view it can be seen that annular ventilation gap 19 is in communication with passage 20 to allow heated air to rise from the region of 20 the housing and skirt 7 to a location outside and above the assembly 1 so that cooling air takes the natural course without obstruction or change of direction thereby enabling optimal heat dissipation. Figure 3 shows with corresponding numbering a cross sectional view of the 25 LED light assembly of figure . This shows the radial ribs 14 which assist in dissipating heat generated in the LED module 3. Figure 4 shows with corresponding numbering a top view of the LED light assembly of figure 1. Heat generated around parabolic reflector 8 is removed by conduction along radial ribs 14 and natural convection which causes heated air to rise up through 30 gap 19.
It will be recognised by persons skilled in the art that numerous variations and modifications may be made to the invention broadly described herein without departing from the overall spirit and scope of the invention. Specifically the geometry of the inner and outer housings can be altered in appearance while 5 retaining the air passage between an LED reflector skirt and an outer housing which defines a gap through which air travels to dissipate heat energy generated by an LED. 10 15 20 25 30 12