ITMI20071886A1 - LIGHT-REDUCED LIGHTING APPARATUS WITH CONTROL OF PHOTOMETRIC DISTRIBUTION OF LIGHT EFFECTIVE - Google Patents

Description

DESCRIPTION of the industrial invention

The present invention relates to a lighting fixture with reduced overall dimensions with control of the photometric distribution of the effective emitted light.

For the lighting of environments or work areas containing VDTs, it is required, on the basis of predefined vision ergonomics criteria regulated by current regulations, to limit the luminance to the value of 1000cd / m <2> for emission angles greater than 65 °.

There is also the need, for plant engineering as well as aesthetic reasons, that the lighting devices used in such environments have reduced dimensions, in particular in the direction perpendicular to the light emission surface or to the screen of said lighting device.

To this end, the lighting devices used in such environments generally mount tubular fluorescent lamps and are generally provided with a reflector having a maximum height between 50mm and 100mm and preferably having two parabolic profile lobes. Such a configuration allows to contain the overall dimensions of the apparatus in the direction orthogonal to the plane of the front screen, but generally does not allow to effectively collimate the reflected rays.

In fact, the limitation of the transverse dimensions also implies the limitation of the focal distance of the reflector, and consequently the fact that the light sources must be placed at a short distance from the reflector itself.

This distance is of the same order of magnitude with respect to the size of the diameter of the light sources themselves. Therefore, as in the very frequent case in which these light sources are Lambertian emission, it occurs that most of the light rays that affect the reflector do not pass through the focal axis of the paraboloid, therefore they cannot be collimated by it, and are diverted to non-zero angles to the normal to the plane of the luminaire screen.

They therefore present a certain angle of divergence with respect to the direction of propagation of the rays that would be emitted by a hypothetical filiform source superimposed on the focal axis of the paraboloid.

The effect of this divergence is particularly significant in reference to those rays that strike the upper part of the reflector.

Figure 1 schematically shows the path of the light rays reflected in a lighting apparatus 101 belonging to the state of the art. Due to the reduced distance between the light source 102 and the reflector 103, the unfocused rays 104 which strike the upper part of the reflector 103 have a significantly higher divergence angle than the unfocused rays which affect the most extreme areas of the profile.

Due to the high divergence, some rays 104 are reflected from the internal surface of the screen 105 and others from the external surface of the same.

In the case not illustrated, in which the screen 105 has refracting elements emerging from the external surface, some rays may even be deviated incorrectly by these elements, causing undesirable effects of light emission at almost grazing angles.

It is possible to verify that the divergence of the rays 104 coming from the upper part of the reflector 103 has a very negative effect on the effectiveness of the front optical screen 105 in controlling the luminance of the apparatus at high angles.

In other words, the upper part of each lobe 106 of the reflector contributes to generating a large number of rays 104 with high divergence which are not correctly redirected by the transparent optical screen 105 even if provided with refracting elements, and which therefore contribute to generating unwanted effects. glare.

The object of the present invention is to obviate the aforementioned drawbacks and in particular to provide a lighting apparatus with reduced overall dimensions which substantially does not generate unwanted glare effects.

A further object of the present invention is that of realizing a lighting apparatus with reduced dimensions which offers an effective control of the photometric distribution of the light emitted. These and other purposes according to the present invention are achieved by realizing a lighting fixture with reduced overall dimensions as set forth in claim 1.

Further characteristics of the device are the subject of the dependent claims.

The characteristics and advantages of a lighting fixture with reduced overall dimensions according to the present invention will become more evident from the following description, which is exemplary and not limiting, referring to the attached schematic drawings in which:

Figure 1 is a schematic sectional view of a lighting apparatus of the prior art;

Figure 2 is a partial sectional view of a first embodiment of the lighting apparatus according to the present invention;

Figure 3 is a partial perspective view of the lighting apparatus of Figure 2;

Figure 4 is a sectional view of a second embodiment of the lighting apparatus according to the present invention;

Figure 5 is a partial sectional view of a third embodiment of the lighting apparatus according to the present invention;

Figure 6 is a partial perspective view of a fourth embodiment of the lighting apparatus according to the present invention;

Figure 7 is a sectional view of a detail of the embodiment of Figure 6;

Figure 8 is a partial perspective view of a fifth embodiment of the lighting apparatus according to the present invention;

Figure 9 is a schematic view of a protuberance present on an optical screen used in the lighting apparatus of the present invention.

With reference to the figures, a lighting fixture with reduced overall dimensions is shown, indicated as a whole with 10.

This lighting device 10 with reduced bulk is provided with a light source 13 enclosed between a reflector 11 and an optical screen 14.

If the reflector 11 has a longitudinal development, as shown in Figures 2-7, this reflector 11 has at least one cylindrical lobe or concentrator 12, for example with a parabolic profile, which collects the light coming from one or more light sources 13 substantially allocated in correspondence with the focal axis of the same 12.

According to a preferential embodiment of the present invention, the profile of each lobe 12 of the reflector can be defined as the combination of two different branches belonging to two different parabolas, joined at the vertex or at any other point of the profile.

In an alternative embodiment not shown, the two branches of the profile of each lobe 12 are constituted by curves of different nature such as for example a hyperbola, an ellipse or in general all the curves described in Cartesian coordinates by a polynomial of order greater than two.

The configuration with two lobes 12, is able to collimate the reflected rays more effectively, but, above all, allows to contain the overall dimensions of the apparatus 10 in the direction orthogonal to the plane of the optical screen 14.

According to the invention, the lighting apparatus 10 is advantageously provided with at least one divergence limiting element 15a, 15b, 15c, 18.

Depending on the particular embodiment, the divergence limiting elements 15a, 15b, 15c, 18 act as divergence limiters of the reflected light 15a, 15b, 15c, i.e. they act on the light rays 104 coming from the reflector 11, or as divergence limiters of the light direct 18, i.e. they act on the light rays 104 directly coming from the source 13.

A common prerogative of all divergence limiting elements 15a, 15b, 15c, 18 is to reduce the divergence angle of the light rays 104 which propagate towards the internal surface of the optical screen 14.

According to a first embodiment of the invention shown in Figures 2 and 3, limiting elements for divergence of the reflected light are provided on the reflector 11 and consist of a plurality of thin blades 15a or fins having surfaces that partially or totally absorb the light incident on them.

These fins 15a are arranged in such a way as to absorb the light of those rays which propagate towards the screen 14 at angles greater than a maximum divergence angle a defined by the geometry and arrangement of the fins 15a themselves.

The fins 15a are placed on the surface of the reflector 11 facing the light source 13 and extend in a direction substantially parallel to the focal axis A over its entire length.

With respect to any plane of section orthogonal to the focal axis A, these fins 15a are distributed on a portion of each lobe 12 of the reflector 11 having dimensions between 20mm and 100mm and preferably between 30mm and 50mm.

The fins 15a can indifferently have a rectangular, triangular, trapezoidal or curvilinear profile section.

The relative distance between two contiguous fins 15a and their extension h in the direction orthogonal to the surface 26 of the reflector 11 facing the light source 13 determine the maximum angle of divergence a of the light rays 17 reflected by the reflector 11 in each portion of the reflector delimited by two fins 15a.

According to a preferential configuration of the fins 15a, this angle is comprised between 10 ° and 45 °.

According to this preferential configuration, at each point of the profile of the fins 15a, the angle formed between the tangent to the profile itself and the perpendicular to the plane of the optical screen 14 can vary between 0 ° and 45 °.

The distribution of the fins 15a on the surface of the reflector 11 is preferably comprised between 0.2 and 6 fins per cm, and in particular between 1 and 3 fins per cm.

The height h of the fins 15a is preferably between 0.2cm and 5cm, and in particular between 0.5 and 1.5cm.

According to a second embodiment of the invention shown in Figure 4, the light divergence limiting elements 15a, 15b, 15c, 18 are divergence limiting elements of the reflected light consisting of plate elements 15b which cover at least a portion of the surface 26 of the reflector 11 by partially or totally absorbing the light incident thereon.

These plate elements 15b are preferably arranged on the surface portion 26 of the reflector 11 closest to the light sources 13 where the divergence effect of the light rays is very significant, and extend in a direction substantially parallel to the focal axis A over the whole the length of the reflector 11.

With respect to any plane of section orthogonal to the focal axis A, these plate elements 15b are preferably distributed on a portion 26 of the surface of each lobe 12 of the reflector 11 with an amplitude comprised between 20mm and 80mm and in particular between 30mm and 50mm.

These plate elements 15b are preferably constituted by thin films applied in various ways to the surface of the reflector 11. For example, the plate elements 15b are glued by means of adhesives, fixed with screws or interference couplings after having provided suitable housings on the reflector block 11. .

According to advantageous embodiments, the plate elements 15b are integrated directly into the reflector 11, being constituted by a portion of reflector 11 with reduced reflectance.

The reduced reflectance portion 15b can be obtained through suitable painting treatments or in general by suitably modifying the angular distribution profile of the intensity of the reflected rays by means of chemical-physical treatments suitable for modifying in a controlled manner the morphological characteristics of the surface of this portion of reflector 15b.

According to a third embodiment of the invention shown in Figure 5, the light divergence limiting elements 15a, 15b, 15c, 18 are divergence limiting elements of the reflected light made directly on the reflector 11 through suitable modifications of the profile in some areas of the reflector the same.

In particular, in the upper zone of each lobe 12 of the reflector 11, a plurality of grooves 15c are made having profiles such as to divert towards the optical screen 14 the light rays coming from the light source 13 redirecting them so that the maximum angle of divergence a that they form with the normal to the plane of the screen 14 is comprised between 20 ° and 45 °.

This angle a is determined by the shape of the profile and by the position of the individual grooves 15c.

Each groove 15c has a first surface 16 suitable for suitably redirecting the light rays 104 and at least a second surface 17, arranged in such a way as to identify with the first surface 16, in any section plane orthogonal to the focal axis A, a profile substantially triangular or trapezoidal (not shown).

In the case of a substantially triangular profile of the section, the second surface 17 intersects the first surface 16 along a line parallel to the focal axis A.

The trace of the surface of each lobe 12 of the reflector 11 on which said grooves 15c are formed has a length preferably between 20mm and 80mm and in particular between 30mm and 50mm.

For each groove 15c the profile of the first surface 16 suitable for reflecting the light rays 104 can be curvilinear or rectilinear and in each point of the profile the line normal to the surface 16 forms with the line connecting this point to the focal axis A an angle which it can be between -30 ° and 30 °.

In a particular embodiment, the first surfaces 16 of the grooves 15c form contiguous portions belonging to the same continuous curve, similar to the geometry characterizing a Fresnel lens. In alternative embodiments, the grooves 15c are instead characterized by surfaces 16 having the same profile.

Preferably, the grooves 15c closest to the vertex of each lobe 12 of the reflector 11 have first surfaces 16 suitable for redirecting the adjacent and symmetrical light rays, therefore such that their profile identifies a single curvilinear portion, preferably parabolic.

The first surface 16 suitable for redirecting the luminous rays 104 is constituted by the same material as the reflector or alternatively coated with highly reflective coat igs deposited by possible different techniques.

The second surface with a preferably rectilinear profile 17 is preferably covered with coatings capable of totally or partially absorbing the light rays 104 incident thereon.

Alternatively, an absorbent plate (not shown) is applied to each second surface 17 to limit the divergence of the light rays 13 made according to the reduced reflectance portion 15b described above in relation to the second embodiment.

According to a fourth embodiment of the present invention shown in Figures 6 and 7, the light divergence limiting elements 15a, 15b, 15c, 18 are direct light divergence limiting elements 18, i.e. which act on the light rays incident on the screen optical 14 which come directly from the light sources 13.

Such direct light divergence limiting elements 18 comprise at least one collimating lens 18 capable of shielding the light rays emitted at angles greater than a certain divergence angle defined by the geometry of the lenses themselves and by their relative position with respect to the light source 13.

In the embodiment illustrated, the shape of each lens 18 is defined by a solid generated by extruding the profile of the generating curve along a direction substantially parallel to the curve C along which the particular light source 13 develops.

Preferably, elements 18 for divergence limiters of direct light formed by two collimating lenses as illustrated in Figure 6 are associated with each light source 13.

Each lens 18 has a first curved surface 19 for the entry of the light rays facing the light source 13 and a second curved surface 20 for the exit of the light rays.

The generating curve of each lens 18 has a profile with a concavity facing towards the light source 13 corresponding to the trace of the incoming surface of the light rays in any plane of section orthogonal to the curve C along which the light source 13 extends.

The profile of the first surface 19 for the entry of the rays is preferably identified by a portion of the circumference, and more generally by a curve described in Cartesian coordinates by a polynomial of order equal to two or higher.

In the case in which it is identified by a section of circumference, the joining the center of this circumference with the point corresponding to the curve C along which the light source 13 develops forms an angle χ between 0 ° and 60 ° and preferably between 20 ° and 45 °.

The profile of the ray entry surface 19 extends over a section whose length is such that the shielding angle φ, identified by the joining the extreme points of this section with the curve C along which the light source 13 extends, is comprised between 20 ° and 90 °, and preferably between 30 ° and 60 °.

The angle ξ, identified by the joining the lower end of the profile of the surface 19 of entry of the rays with the point corresponding to the curve C along which the light source 13 develops, with respect to the vertical passing through this point, determines the extension of the portion surface of the unshielded source. This angle ξ is preferably comprised between 15 ° and 60 °, and in particular between 25 ° and 45 °.

The surface 19 of entry of the light rays can also present a matrix of protuberances of nanometric dimensions arranged according to the moth's eye pattern, such as to give it the characteristic of transmitting almost all of the incident rays, including those rays that arrive with high angles of incidence.

The profile of the second surface 20 for the emission of the rays can be identified by an arc of circumference, or parabola, or hyperbola or more generally by a curve described in Cartesian coordinates by a polynomial of order equal to two or greater.

The second surface 20 for emitting the light rays is also characterized by the presence of a plurality of micro-prisms 21 which extend along the entire length of the lens 18 on a portion of the profile of the generating curve or on the entire profile.

These prisms 21 preferably have different heights and profiles according to their position along the profile.

Each lens 18 is alternatively made of glass or of transparent thermoplastic material, preferably of polycarbonate or acrylic.

In embodiments not shown, the lighting apparatus 10 according to the present invention is provided with elements 15a, 15b, 15c for limiting the divergence of the reflected light, and with elements 18 for limiting the divergence of direct light.

According to alternative embodiments of the lighting apparatus 10 object of the present invention, the reflector 11 is made in such a way that each lobe has a main axis of inertia perpendicular to the plane of the optical screen 14 and that it has one or more planes of symmetry all passing through the aforementioned main axis of inertia. According to this scheme the luminaire can mount one or more light sources 13 consisting of circular or compact fluorescent lamps, gas discharge lamps or electroluminescent sources in organic or inorganic material.

In accordance with the aforementioned alternative embodiments of the invention, the construction details of the divergence limiting elements 15a, 15b, 15c, 18 are linked to the specific geometry of the reflector 11 and of the light sources 13 mounted on the lighting device 10.

In particular, in the case of the embodiment of Figure 8, the lighting apparatus 10 assumes a configuration with circular symmetry and the reflector 11 has an axis of symmetry B perpendicular to the plane of the optical screen 14.

In the particular embodiment illustrated, the reflector 11 is constituted by a solid of revolution having a substantially parabolic profile section whose axis of symmetry B coincides with the axis of symmetry of the light source 13, which in this embodiment consists of a fluorescent lamp 13 with circular development. In particular, the profile of each lobe 12 of the reflector 11 conforms to the profile already described with reference to the configuration with longitudinal axis.

In each plane of section orthogonal to the screen 14, the point corresponding to the focal axis A of each lobe 12 of the reflector 11 is substantially coincident with the point corresponding to the curve C of circular development of the lamp 13, i.e. being the focal axis A of the reflector 11 substantially superimposed on the circular development curve C of the lamp 13.

In accordance with this embodiment of the invention, the divergence limiting elements 15a, 15b, 15c, 18 have a cross-sectional profile corresponding to that described in relation to the embodiments of the invention described above, but do not extend along a rectilinear axis as in these embodiments, but are preferably configured as solids of revolution with axis coinciding with the axis B of the reflector.

Figure 8 shows an exemplary embodiment in which these divergence limiting elements are made in lamella form 15a.

According to a further aspect of the present invention, the optical screen 14 of the lighting apparatus 10 according to the present invention advantageously has, on its external surface 22 for the emission of the light rays, a plurality of refracting elements 23.

These refracting elements 23 are alternatively constituted by solids with conventional geometry, such as for example pyramids or truncated pyramids, cones or truncated cones, spherical or aspherical lenses, or preferably made in the form of axial-symmetrical protuberances which taper in the direction perpendicular to the plane of the screen. 14. Advantageously, the axial symmetrical protuberances 23 are constituted by solids of revolution whose generatrix is identified by at least a first curvilinear section 24 which has a concavity facing towards the inside of the solid of revolution 23, and at least a second curvilinear section 25 also it has a curvature facing towards the inside of the solid of revolution but a radius of curvature Ri less than or equal to the radius of curvature R2 of the first section 24.

In addition or as an alternative to the second curvilinear portion 25, this generatrix comprises a rectilinear portion 26 terminating at the point of intersection with the base plane of the screen 14. The portions 24 and 25 of the generatrix are preferably joined at a point with a common tangent.

Alternatively, in an embodiment variant not shown, the portions 24 and 25 of the generator are joined in a point which identifies a discontinuity in the first derivative of the function describing the profile of the generator and therefore a point of the cusp.

Each of the curvilinear segments 24,25 consists of one or more curvilinear segments, each of which can be described in Cartesian coordinates by a polynomial of order greater than or equal to two.

The protuberances 23 are preferably arranged to form a hexagonal cell matrix so that each protuberance 23 is identified by the intersection of the solid of revolution and a parallelepiped with a hexagonal base inscribed in the base circle of this solid of revolution 23. all analogous, the protuberances 23 can be arranged to form a matrix with square, pentagonal, octagonal cells and so on.

The particular shape of the profile of the generators of the solids of revolution 23 leads to an even more effective control of the photometric distribution produced by the optical screen 14.

From the above description the characteristics of the device object of the present invention are clear, as are the relative advantages.

Finally, it is clear that the lighting apparatus thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the invention; furthermore, all the details can be replaced by technically equivalent elements. In practice, the materials used, as well as the dimensions, may be any according to the technical requirements.

Claims (24)

CLAIMS 1. Lighting apparatus (10) with reduced overall dimensions comprising at least one light source (13) interposed between a reflector (11) and an optical screen (14) characterized in that it comprises at least one element (15a, 15b, 15c, 18) light divergence limiter adapted to reduce the divergence angle of the light rays directed towards said optical screen (14). 2. Space saving luminaire (10) according to claim 1 characterized in that said divergence limiting element (15a, 15b, 15c, 18) is a diverging light limiting element (15a, 15b, 15c) reflected adapted to reduce the angle of divergence of the light rays reflected by said reflector (11). 3. Lighting apparatus (10) with reduced overall dimensions according to claim 2 characterized in that said at least one element (15a, 15b, 15c) limiting the divergence of the reflected light comprises a plurality of fins (15a) arranged on a portion of the surface (26) of said reflector (11) facing said at least one light source (13), said fins (15a) having surfaces made of a material capable of at least partially absorbing the light rays incident thereon. 4. Lighting apparatus (10) with reduced overall dimensions according to claim 3 characterized in that the angle formed between the tangent to the profile of said fins (15a) and the perpendicular to the plane of said optical screen (14) is between 0 ° and 45 °. 5. Lighting apparatus (10) with reduced overall dimensions according to claim 3 or 4 characterized in that the distribution of said fins (15a) on said surface (26) of the reflector (11) is comprised between 0.2 and 6 fins per cm. 6. Lighting apparatus (10) with reduced overall dimensions according to any one of claims 3 to 5 characterized in that the height (h) of said fins (15a) is comprised between 0.2cm and 5cm. 7. Lighting apparatus (10) with reduced overall dimensions according to claim 2 characterized in that said at least one element (15a, 15b, 15c) limiting the divergence of the reflected light is at least one plate element (15b) which covers at least a portion of a surface (26) of said reflector (11) facing said at least one light source (13), said at least one plate element (15b) being made of a material capable of at least partially absorbing the light rays incident thereon. 8. Lighting apparatus (10) with reduced overall dimensions according to claim 2 characterized in that said at least one element (15a, 15b, 15c) limiting the divergence of the reflected light is at least one plate element (15b) which covers at least a portion of a surface (26) of said reflector (11) facing said at least one light source (13), said at least one plate element (15b) being constituted by a portion of reflector (11) with reduced reflectance. Lighting apparatus (10) with reduced overall dimensions according to claim 2 characterized in that said at least one element (15a, 15b, 15c) limiting the divergence of the reflected light comprises a plurality of grooves (15c) made on at least a portion of a surface (26) of said reflector (11) facing said at least one light source (13). Compact lighting device (10) according to any one of the preceding claims, characterized in that said divergence limiting element (15a, 15b, 15c, 18) is a divergence limiting element (18) for direct light to reduce the angle of divergence of the light rays coming directly from said at least one light source (13). Lighting apparatus (10) with reduced overall dimensions according to claim 10 characterized in that said at least one element (18) limiting the divergence of direct light comprises at least one lens having a first curved surface (19) for the entry of the rays luminous lights facing said at least one light source (13) and a second curved surface (20) for the output of the light rays. Compact lighting apparatus (10) according to claim 11 characterized in that said first curved surface (19) has a concavity facing towards said at least one light source (13). 13. Lighting apparatus (10) with reduced overall dimensions according to claim 11 or 12 characterized in that the profile of said first curved surface (19) is identified by a section of circumference. Lighting apparatus (10) with reduced overall dimensions according to any one of claims 11 to 13 characterized in that said first curved surface (19) has a matrix of protuberances of nanometric dimensions arranged according to the moth's eye pattern. Compact lighting apparatus (10) according to any one of claims 11 to 14 characterized in that said second curved surface (20) has a plurality of prisms (21). Lighting device (10) with reduced overall dimensions according to one of the claims 13 to 15 characterized in that said at least one light source (13) has a development along a curve (C), which joins the center of said circumference with a point corresponding to said curve (C) forming, with respect to the vertical passing through said point, an angle (χ) comprised between 0 ° and 60 °. Compact lighting fixture (10) according to one of claims 13 to 16 characterized in that said profile of said first curved surface (19) extends along a length such that the shielding angle (φ), identified by the joining the extreme points of this section with said development curve (C) of said light source (13) it is comprised between 20 ° and 90 °. 18. Lighting device (10) with reduced overall dimensions according to any one of claims 13 to 17 characterized in that it joining the lower end of the profile of said first curved surface (19) with a point corresponding to said development curve ( C) of said light source (13) forms, with respect to the vertical passing through said point, an angle (ξ) comprised between 15 ° and 60 °. 19. Lighting apparatus (10) with reduced overall dimensions according to any one of the preceding claims, characterized in that said optical screen (14) has a plurality of refracting elements (23) on its surface (22) for emitting light rays. 20. Lighting apparatus (10) with reduced overall dimensions according to the previous claim characterized in that said plurality of refracting elements (23) are constituted by solids of revolution whose generator is identified by at least a first (24) and a second (25 ) curvilinear section with concavity facing towards the inside of said solid of revolution (23), said second curvilinear section (25) having a radius of curvature (R1) less than or equal to the radius of curvature (R2) of said first curvilinear section ( 24). 21. Lighting apparatus (10) with reduced bulk according to claim 19 characterized in that said generator of said protuberances (23) comprises a rectilinear portion (26) terminating at the base plane of said protuberance (23). 22. Lighting device (10) with reduced overall dimensions according to any one of the preceding claims characterized in that said reflector (11) has at least one lobe (12) with a parabolic profile, at least one light source (13) being arranged substantially in correspondence with the 'focal axis (A) of each parabolic lobe (12). 23. Lighting apparatus (10) with reduced overall dimensions according to any one of the preceding claims characterized in that said at least one light source (13) is at least one fluorescent tubular light source (13). Compact luminaire (10) according to any one of the preceding claims characterized in that said at least one light source (13) is at least one circular fluorescent light source (13)