A CEILING-MOUNTED LUMINAIRE FOR AMBIENT LIGHTING Technical Field

This invention relates to a sealed overhead luminaire, for ambient lighting, with powerful LED lamps arranged in a line.

This invention will be described in particular with reference to lighting engineering for interiors in civil and/or industrial environments. However, it shall be understood that this in no way limits the scope of the invention, since the invention may also be advantageously used in different contexts, such as lighting for shop windows, exhibition halls, road tunnels or even for lighting exteriors, whether public or private. Background Art

The use of LEDs as lamps is rapidly spreading as an alternative to more conventional lighting systems which consist, for example, of incandescent lamps, with a lighting filament, or fluorescent lamps such as tubes using neon or similar gases.

LEDs, that is to say, light emitting diodes, are used in prior art overhead luminaires, their arrangements in line requiring the use of sets of low-powered LEDs which are separated from each other by a suitable distance, and which are mounted in such a way as to produce direct lighting in the environment where they are fitted.

Such prior art luminaires have intrinsic functional limitations which greatly limit their possibilities for use in lighting engineering. Indeed, the use of direct- lighting LEDs is only tolerated when the LED lamps are very low-powered, since in general LED lamps produce intense luminance or brightness and may cause glare, reduced visual capacity, and can even damage eyes.

For the above-mentioned reasons, where it is necessary to achieve light intensity suitable for various needs, since the rated emission power of individual LEDs cannot be increased, currently the only way allowed by prior art lighting is that of using increasing numbers of LEDs so as to obtain the required level of lighting.

Moreover, the low power of such types of LEDs makes such prior art luminaires suitably usable in applications in which the surface used is relatively close to the lamp, as is the case, for example, with table lamps. If the surface used is the floor of a room, or the ground when lighting exteriors, such luminaires are completely unsuitable for providing adequate lighting.

Attempts to overcome such limitations were made by using high-powered

LEDs.

However, they did not achieve appreciable success due to a series of disadvantages mainly represented by the fact that the lighting obtainable with LEDs in a line in general is not uniform, being accompanied by the formation of clear areas of shadow which, in the case of high-powered LEDs, are even more accentuated and obvious. These areas of shadow - even in the presence of an acceptable average theoretical lighting condition - force the eye to perform continuous adaptive work - tiring people and greatly penalising the environmental wellbeing.

In addition, the high power of the LEDs also enhanced all of the disadvantages linked to glare referred to above and its hazardousness in terms of accidents. As a result of all of these disadvantages, up to now there are no prior art overhead luminaires with high-powered LEDs in line which give fully satisfactory results in terms of the various above-mentioned situations.

Disclosure of the Invention

The main aim of this invention is to overcome such disadvantages by providing an overhead luminaire of the type equipped with high-powered LEDs in line, with which it is possible to obtain good lighting in large volume civil and/or industrial environments and, more particularly, in environments which are even several metres high.

The second aim of the invention is to allow the production of an overhead luminaire in which the level of glare is zero, or in any case its extent is absolutely negligible and well below the albeit minimum threshold for hazard or visual distress.

The third aim of the invention is to allow the production of a sealed overhead luminaire which, as such, is able to house both the LEDs and the service components, dissipating the heat emitted during its operation without compromising the functionality and reliability of the luminaire and the safety of people in terms of the electric risk.

A fourth aim of the invention is that of obtaining an overhead luminaire in which the luminaire casing is substantially not used for heat dissipation, thus allowing the use of the most diverse materials and in particular plastic materials. This is an advantage in terms of the cost of construction and the widest freedom of choice for the aesthetic forms of the overhead luminaire.

Accordingly, this invention achieves said aims with an overhead luminaire comprising the technical features described in one or more of the appended claims. Brief Description of the Drawings

The technical features of the invention, with reference to the above aims, are clearly described in the claims below, and its advantages are more apparent from the detailed description which follows, with reference to the accompanying drawings which illustrate a preferred embodiment of the invention provided merely by way of example without restricting the scope of the inventive concept, and in which:

Figure 1 is a perspective assembly view of an overhead luminaire according to the invention, shown in an operating configuration, with some parts cut away to better illustrate others;

Figure 2 is a perspective rear assembly view of the overhead luminaire of Figure 1;

Figure 3 is a top plan view of the overhead luminaire of Figure 2;

Figure 4 is a longitudinal section of the overhead luminaire according to the line rv - rV in Figure 2;

Figure 5 is an enlarged partial view of the section of Figure 4;

Figure 6 is a cross-section of the overhead luminaire according to the line VI - VI of Figure 3.

Detailed Description of the Preferred Embodiments of the Invention

With reference to the accompanying drawings, the numeral 1 denotes in its entirely an overhead luminaire for ambient lighting.

The overhead luminaire 1 basically comprises high-powered LEDs 2 having optical axes 2a arranged along a line 3, preferably a straight line, and the same number of reflectors 4 which are associated with each LED 2.

The reflectors 4 have a tubular shape diverging from a narrow, apical first end 5, where a respective LED 2 is substantially located, to a widened, distal second end 6, where the reflectors 4 have outlines 7 which are closely adjacent to each other longitudinally to the line 3 of the LEDs 2.

The set of LEDs 2 and the respective reflectors 4 form a kind of lighting strip which is substantially continuous along the entire line 3.

The reflectors 4 preferably have the shape of a truncated cone, with vertex angles 30 which are substantially between 90° and 140°.

However, the reflectors 4 may have different geometric shapes, provided that they are diverging. For example, the shape of a truncated pyramid, with a polygonal outline of its base surface.

As shown in Figures 1, 4, 5 and 6, the reflectors 4 are structurally integrated in a box-shaped first single body 8, basically having the shape of a parallelepiped, with elongate lateral walls 27 parallel with the line 3 of the LEDs 2.

The lateral walls 27 of the box-shaped body 8 and the exterior surfaces 28 of the reflectors 4 between them form an inner compartment 9 in the box-shaped body 8 which is designed to house the service components of the LEDs 2 which comprise, amongst other things, one or more power supply units 10 for supplying electricity to the overhead luminaire 1.

The positioning of the LEDs 2 in a position retracted towards the inside of the reflectors 4 and the geometric proportions of the reflectors 4 themselves contribute to obtaining conditions suitable for preventing the eye of the observer present in the space opposite the overhead luminaire 1 from seeing the LED or LEDs 2 in a way that causes the eye to be dazzled by them, the LEDs having a rather high intensity brightness.

The overhead luminaire 1 also comprises diffusers 11 for the light emitted by the LEDs 2. The diffusers respectively face the second end 6 of the reflectors 4.

The diffusers 11 comprise lenses 12 with biconvex profiles, which, in a longitudinal plane x, y containing the line 3 of the LEDs 2 and in a plane x, z transversal to said line 3, have convex profiles orientated in opposite directions.

It should be noticed, in particular by comparing Figures 5 and 6, that in the longitudinal plane x, y containing the line 3 of the LEDs 2 [Figure 5], the convexity of the lenses 12 is towards the apex of the reflector 4, but at the plane x, z transversal to the line 3 of the LEDs 2 it is orientated in the opposite direction [Figure 6].

The lenses 12 are shaped in such a way that they have focal points positioned substantially at the LEDs 2. This allows the light cones with uniform brightness to be obtained and such that they allow the lighting of surfaces used which are even several metres away from the LEDs 2. In that way, the overhead luminaire 1 may advantageously be used for interior lighting in large volume environments such as industrial warehouses, with the overhead luminaire 1 on the ceiling or in any case at a height of several metres above the floor.

Even the diffusers 11 are structured integral with a shell-shaped element forming a second single body 13 whose shape surrounds and at least partly contains the first single body 8. Coupling means positioned between the two bodies allow them to be anchored to each other in an operating condition in which the bodies act as one piece.

The overhead luminaire 1 also comprises a heat dissipator 14, preferably made of aluminium alloy, which abuts the first end 5 of the respective reflectors 4, that is to say, it is placed in contact with the LEDs 2 in the space outside the reflectors 4. The dissipator 14 is provided with long heat exchange fins 15 projecting parallel with each other away from the LEDs 2.

The dissipator 14 is housed in a cavity 17 made in the geometric shape of a shell-shaped third single body 16 which can be associated with brackets 29 provided for fixing the overhead luminaire 1 to the supporting structures.

Although during use the high-powered LEDs 2 generate a rather high level of heat power, the dissipator 14 is able to keep the overhead luminaire 1 in a range of temperature values which is well below the critical values for damage to the LEDs 2 and/or all of the accessory components, including the structural elements of the overhead luminaire 1.

Due to the high heat exchange efficiency of the dissipator 14, not even the overhead luminaire structural elements (for example the first, second and third single bodies 8, 13, 16) are subjected to temperatures that are too high. Advantageously, this allows said bodies to be made of plastic material, without them being subjected to excessive tensions and deformations in the material of which they are made, or even the smallest external modifications, which would change their good appearance.

Again observing Figures 5 and 6, it is possible to see how the overhead luminaire 1 also comprises - within the shell-shaped third single body 16 - sealing means 19 which make the overhead luminaire 1 hermetically impermeable to infiltration by the weather. More specifically, the means 19 are interposed between at least the first and third single bodies 8, 16 and comprise elements which are shaped to match each other and which can be associated in a snap-on fashion, represented by a U-shaped groove 22 made in the first body 8 and a tab 23 supported on the third body 16 which can be inserted frontally into the groove 22.

An annular seal 24 is housed in, and in contact with, the U-shaped groove 22, and is pressed into place by the thrust from the tab 23.

A further contribution to the hermetic seal is provided by the interaction of the edges 20 and 21 of the first and third bodies 8, 16 which can be associated with each other, which, as well as helping to create the mechanical interconnection between the first and third bodies 8, 16, also operate in conjunction with each other to form labyrinthine paths which present a first obstacle to infiltrations before such infiltrations can reach the elastic annular seal 24.

Due to the high degree of watertight seal of the overhead luminaire 1, the latter is able to satisfy the minimum requirements of the strictest international standards, making it usable advantageously and without distinction both indoors and outdoors, even without protection from the weather.

In addition to fulfilling the aims indicated, the invention provides the further advantage of an energy saving of around 50% compared with conventional lighting systems which use neon tubes and, even more, compared with incandescent lamps. Further advantages are the fact that only minimal maintenance is required due to the very reliable operation of more than 50,000 hours of continuous use.

Yet another advantage is the fact that the invention provides a high level of safety against the risk of electrical accidents since the overhead luminaires 1 are powered by the internal power supply units with low direct voltage of 12/24/48 V, as required by the strictest safety standards.

The invention described above is susceptible of industrial application and may be modified and adapted in several ways without thereby departing from the scope of the inventive concept. Moreover, all details of the invention may be substituted by technically equivalent elements.