WO2012059790A1

WO2012059790A1 - Projector with solid state light sources for street lighting or the like

Info

Publication number: WO2012059790A1
Application number: PCT/IB2010/055023
Authority: WO
Inventors: Moreno Vittorio Rodighiero
Original assignee: Nanto Srl
Priority date: 2010-11-05
Filing date: 2010-11-05
Publication date: 2012-05-10

Abstract

A projector (1) with solid-state light sources (6) for street lighting or the like, comprises a case (2) that defines a main extension plane (Σ), a longitudinal axis (L) and a transverse axis (W) in mutually orthogonal relationship. The case (2) houses a plurality of LED light sources (6', 6", 6'") and a cap (3). Each of the LED light sources (6', 6", 6'") has a predetermined FWHM value and a main axis of the FWHM parameter (H, H', H", H'"). The cap (3) comprises a plurality of reflective surfaces (7', 7") for reflecting at least part of the emission of the LED sources (6', 6", 6'"). The LED sources (61, 6", 6'") are in such an arrangement relative to the reflective surfaces (71, 7") that none of them is subjected to at least one total reflection of the whole light emission within its optical FWHM parameter, at least one of the LED sources (6', 6", 6'") having its main optical axis (H', H", H'") oriented toward a target (T) without impinging upon none of said reflective surfaces (7', 7"). Advantage: reflections of the light emission within the optical FWHM parameter are reduced and the performance of the projector (1) is maximized.

Description

PROJECTOR WITH SOLID STATE LIGHT SOURCES FOR STREET LIGHTING OR THE LIKE

Field of the invention

The present invention generally finds application in the field of lighting technology and namely relates to a projector with solid-state light sources for street lighting, namely for the lighting of streets, squares, gardens, parking lots, large open or closed spaces, such as arenas, theaters, hangars, industrial plants and the like.

Background art

Most street lighting systems heretofore has mainly used halogen sodium- vapor or metal-iodide light sources.

The use of these light sources that have a luminous efficiency of 40-60 Im/W and more has afforded a considerable reduction of power consumption as compared with incandescent lamps in which the luminous efficiency of the illuminating body is about 13 Im W. Nevertheless, this type of light sources still has the drawback of emitting a colored light, mainly tending to yellow, having an insufficient power, and a light emission that is not evenly distributed or appropriately oriented toward the target to be illuminated. In order to obviate this drawback, Light Emitting Diode (LED) sources have been developed, which can emit a white light and whose light source can achieve an efficiency of more than 100 Im W.

Examples of such LED projectors have been disclosed in documents JP 20010248020, JP20010248019, EP 20040008529, U200501645, WO2008/100124. A further drawback of prior art LED projectors for street lighting and with power LEDs in general is glare, occurring when an observer is exposed to a beam having excessive luminance in his/her field of view, which can cause sight-impairing or disturbing effects.

WO2010/070565 discloses a LED-based street lighting device, in which most of the light beam emitted from the sources and comprised within the optical PWHM parameter is entirely reflected by the reflective surfaces before being directed to the target. This solution tends to avoid dispersion of the light beam and to improve luminous efficiency as compared with prior art lighting devices.

Nevertheless, part of the luminous energy emitted from the reflective surfaces is transformed into heat and is absorbed by the projector, which causes an energy loss and hence reduced luminous efficiency.

Optimization of the device would require a reduction of light source reflections within their FWHM parameter, while maintaining an optimal distribution of light emission and ensuring a relatively uniform light beam on the target.

Furthermore, while this prior art street lighting device reduces glare to acceptable limits, under certain sight conditions this phenomenon is not completely eliminated and still causes some uncomfort.

Disclosure of the invention

A main object of the present invention is to obviate the above drawbacks by providing a LED projector that affords optimized operation and uniform light distribution namely in streets, public spaces and outdoor sites, and/or over large indoor spaces for public, industrial and private use. A further object is to conceive a projector for a LED-based lighting device that provides a further reduction of light losses caused by radiation reflection on reflective surfaces, as compared with prior art lighting devices. Another object is to provide a projector that can increase the overall luminous efficiency by compensating for any insufficient optical performance area.

Yet another object is to almost entirely eliminating glare from all angles of view.

These and other objects, as better explained hereafter, are fulfilled by a projector with solid-state light sources for street lighting or the like, as defined in claim 1. The projector of the invention comprises an outer supporting case that defines a main extension plane, having a longitudinal axis and a transverse axis in mutually orthogonal relation, said case housing a plurality of LED sources and a cap with reflective surfaces, wherein each of said LED sources has a predetermined FWHM value and a main axis of said FWHM, and wherein said cap comprises a plurality of reflective surfaces for reflecting at least part of the emission of said LED light sources. The projector is characterized in that said LED sources are in such an arrangement relative to said reflective surfaces of said cap that none of them is exposed to at least one total reflection of the whole light emission within its optical FWHM parameter, at least one of said LED sources being oriented with its main optical axis directed toward a target without impinging upon none of said reflective surfaces.

With this configuration, the projector can reduce the number of reflections in the light emission that falls within its optical FWHM parameter and maximize its luminous efficiency due to a lower dispersion of energy in the form of heat. Conveniently, light sources comprise at least one first series of LEDs with respective axes of symmetry of the FWHM parameter reflected at least once by the reflective surfaces of the cap, to mainly illuminate areas of the target that are closer to the projector.

Furthermore, the LEDs of the first series are mounted to at least one pair of electronic boards located in the proximity of the opposed longitudinal edges of the case in substantially symmetrical positions with respect to a longitudinal plane of symmetry substantially orthogonal to the main extension plane.

The light sources also comprise at least one second series of LEDs which are in such an arrangement and orientation that at least one of them has its main axis of symmetry unreflected by the reflective surface of the cap.

The reflective surface comprises at least one first series of primary reflective surfaces whose profile is substantially symmetrical with respect to a plane of symmetry substantially perpendicular to the main extension plane and passing through the longitudinal axis.

Advantageously, the primary reflective surfaces of the first series are mainly located in a first area of the cap, substantially facing the first series of LEDs, and have such an orientation as to reflect the light emitted from the first series of LEDs to an area of the target that is closer to the projector.

Conveniently, the reflective surface comprises at least one second series of primary reflective surfaces mainly located in a second area of the projector and having such an orientation as to reflect light into an area of the target that is farther from the projector, and are mainly located in a second area of the projector with a profile substantially asymmetrical with respect to a plane orthogonal to the main extension axis that passes through the transverse axis.

The reflective surface comprises at least one additional series of reflective surfaces and/or secondary refractive surfaces, located over the cap in longitudinally offset positions relative to the first two series, to distribute the light beam to insufficiently illuminated areas for a more uniform lighting profile.

Conveniently, the projector has cooling means for dissipating the heat generated by said LED sources, wherein the cooling means include pairs of parallel and outwardly radially directed cooling fins, which are integral with the case and thermally connected to the LEDs for improved heat exchange.

Brief description of the figures

Further features and advantages of the invention will be more apparent from the detailed description of several preferred but non-exclusive embodiments of a street lighting projector or the like according to the invention, which are described as non-limiting examples with the aid of the annexed drawings, in which:

FIG. 1 is a three-dimensional diagram of the light emission from a LED source, with respect to a Cartesian system;

FIG. 2 shows two graphs representing the energy efficiency of the emission of FIG. 1 projected on two mutually orthogonal planes;

FIG. 3 is a top perspective view of a first embodiment of the projector of the invention;

Fig. 4 is a bottom perspective view of the projector of the invention as shown in FIG. 3;

FIG. 5 is a partially suctioned view of the projector of FIGS. 3 and 4, along a plane IV-IV;

FIG. 6 is a partially suctioned view of the projector of FIGS. 3 and 4, along a plane V-V;

FIG. 7 is a view of a detail of the projector shown in FIG. 5;

FIG. 8 is a view of a detail of the projector shown in FIG. 6;

FIG. 9 is a bottom plan view of a second embodiment of the projector of the invention;

FIG. 10 is a bottom plan view of a third embodiment of the projector of the invention;

FIG. 11 is a general perspective view of a projector of the invention, when mounted to a post to provide a street lamp;

FIG. 12 is plan view of the projector and lamp of FIG. 11.

Detailed description of a preferred embodiment

Referring to the above figures, a projector of the invention is described, which is generally referenced 1.

The projector 1 is namely designed for the lighting of streets, parking lots, squares, arenas and outdoor or indoor spaces in general, but may be also used for the lighting of indoor or partially indoor sites, such as industrial plants, hangars, gyms, sports halls, theaters, meeting, entertainment, worship sites and in general wherever optimal and uniform lighting and minimized glare are required.

The projector 1 is equipped with solid-state LED sources, characterized by a predetermined "optical FWHM parameter" (Full Width at Half Maximum), as accurately defined below.

FIG. 1 shows a Cartesian axes system O, x, y, z with a general LED source at the origin O, and with z axis coinciding with the main axis of symmetry H of light emission and having a positive direction in the upper half-space of the surface S from which the light beam is emitted. R designates a vector that represents a general light ray emitted from the surface S, which is centered at O and is characterized by a unit vector r. The angles $_x and 9y that the unit vector r forms with the x, y axes respectively define an ordered pair $ = ($_x, 9y) that uniquely identifies the angular vector of the ray R.

Assume now that E_max is the maximum value of the amount of energy emitted from the LED in the various directions and E is the total amount of light energy emitted from the LED in the direction of the angular vector

FIG. 2 shows two normalized graphs of the relative angular emission of luminous energy from the LED 6, i.e. the E/E_max ratio, as a function of the angular quantities 9-_x, $_y respectively. The two graphs represent the E/E_max curve in the plane defined by the axes x, z and the E/E_max curve in the plane defined by the axes y, z respectively, corresponding to two distinct profiles of the E/E_max scalar ratio as a function of $_x, 9

The optical FWHM parameter is defined as FWHM = (FWHIv _x, FWHM$_Y), i.e. the pair of scalar entities corresponding to the values of the angular ranges subtended by the portions of the two curves from 0,5 to 1 of the

E/E_max ratio, along the axes of the angular values , $_y respectively.

As used herein, the conventional term "target" will designate a limited area R of the street or space which is illuminated by the projector 1 , and may be combined with other adjacent and similar areas T that form the target of other projectors so that a street or a similar space may be entirely and uniformly illuminated.

Referring to FIGS. 3 - 11 , the projector 1 comprises a generally concave outer support case 2 having an inner cavity with one open side, and having a longitudinal axis of symmetry L and a transverse axis W in mutually orthogonal relationship. The axes L and W define a main extension plane∑, that may be conveniently assumed to be horizontal, and a pair of geometrical planes, i.e. longitudinal Ω and transverse Ψ planes, in orthogonal relationship to each other and to∑, that may be conveniently assumed to be vertical. The support case 2 is preferably made of a relatively rigid material, to protect the various parts of the projector and houses a lighting cap, generally referenced 3, in its inner cavity.

Preferably, the case 2 has conventional anchoring means 4, for mechanical and electrical connection of the projector 1 to a post P, a wall or to a movable or stationary support. Such anchoring means 4 may include, for instance, a tubular sleeve through which a cable 5 extends, for connection to a power supply line. A plurality of solid-state light sources, generally referenced 6, preferably consisting of power LEDs, are held in the case 2. Furthermore a surface, generally referenced 7, is formed on the inner surface of the cap 3, which is also partially concave and held within the outer support case 2. The LEDs that form the light sources 6 are generally sold as packages, each composed of a thin layer of doped semiconductor material (diode) based on GaAs (Gallium Arsenide), GaP (Gallium Phosphide), GaAsP (Gallium Arsenide Phosphide), SiC (Silicon Carbide) and GalnN (Gallium Indium Nitride), embedded in an enclosure made of a clear polymer- or glass-based material, with a hemispherical or lenticular shape to promote the concentration of the light flux. Non limiting examples of these LEDs are the XP-G model, manufactured and sold by Cree®, with a light flux to 493 Im and an output of 92 Im/Watt at a test current of 1 ,5 A, and the Rebel-ES model, manufactured and sold by Lumileds® (Philips) with a light flux to 310 Im at a test current of 1 A.

Apart from the lenticular enclosures in which the emissive material is embedded, the LED-based light sources 6 are preferably mounted to the projector with no additional refractive system, i.e. with no lenses or meniscus elements of any shape or material, physically coupled to the unit to change its light projection, in terms of both the FWHM parameter of the emissive profile and the spectral emissive profile (wavelength and color).

In the embodiments shown in the figures, the LED sources 6 are located in the case 2 in different positions to emit light beams toward various areas of the target T.

Particularly, the light sources 6 include a first series of LEDs 6', located in such positions that their light beams have the axis of symmetry H' of the FWHM parameter reflected at least once by the reflective surfaces of the cap 3.

According to the invention, the light sources 6 also comprise at least one second series of LEDs 6" which are located in the case 2 in such positions that at least one of them has its main axis of symmetry H" unreflected by any one of the reflective surfaces of the cap 3.

Both LEDs 6' and LEDs 6" have such orientations relative to the reflective surface 7 of the cap 3 that none of these light sources is subjected to at least one total reflection of the whole light emission within its optical FWHM parameter. Thus, the overall light emission generated by both series of LEDs 6' and 6" is very poorly subjected to dispersion of luminous energy, and maximizes the luminous efficacy of the projector 1 to above 80%. In a first embodiment, depicted in FIGS. 3, 4, the series 6' of LEDs are fixed, in array arrangements, to at least one pair of boards 8', placed in the proximity of the opposite edges of the cap 3 in mutually facing and substantially symmetrical positions relative to the longitudinal plane Ω. This function of the first series 6' of LEDs is mainly to illuminate the areas T of the target that are closer to the projector 1 , as schematically shown in FIGS. 11 and 12.

Conveniently, the boards 8' are inclined at an angle a' ranging from 90° to 180° with respect to the main extension plane∑ and the longitudinal plane Ω so that the axis of optical symmetry of the FWHM of the LEDs faces upwards, i.e. toward the surface of the cap 3.

Particularly, each board 8' advantageously comprised of a substrate of high thermal conductivity and low thermal resistivity heat conducting material. A layer of insulating material is laid on such substrate, and acts as an anchor base for circuits, LEDs and auxiliary electronic components, such as by-pass diodes and connectors, not shown and typical for this components. The LEDs of 6" type are arranged in clusters on a single board 8" of the same type as the boards 8'. The board 8" is secured to the case 2 and located next to one end of the cap 3. Such board 8" is inclined to the transverse plane Ψ, at an angle a" from 0° to 90° so that the axis of optical symmetry of the FWHM of the LEDs faces downwards, i.e. away from the cap 3. Thus, the function of the light sources 6" is to mainly illuminate the areas T" of the target that are farther from the projector 1 , as schematically shown in FIGS. 9 and 10. The inner surface 7 of the cap 3 is differentiated according to the reflection area on the target T, as clearly shown in FIGS. 4-8.

Particularly, the inner surface 7 comprises at least one first series of primary reflective surfaces 7', which are mainly located on a first limited area A of the cap 3 and have a profile that is substantially symmetrical to the longitudinal vertical plane Ω, as clearly shown in FIGS. 5 and 7.

Conveniently, the primary reflective surfaces T are located in a position that substantially faces toward the first series 6' of LEDs, and have such an orientation as to reflect the light emitted from said series 6' of LEDs to the area T of the target that is closer to the projector 1.

The inner surface 7 further comprises at least one second series of primary reflective surfaces 7", which are mainly located on a second limited area B of the projector 1 and have a profile that is asymmetrical to the transverse plane Ψ, as clearly shown in FIGS. 6 and 8.

Conveniently, the primary reflective surfaces 7" are located next to a longitudinal end of the case 2 in a substantially central position along the longitudinal axis L.

Particularly, the primary reflective surfaces 7" are located in a position that substantially faces toward the second series 6" of LEDs, and have such an orientation as to reflect light to an area T" of the target that is farther from the projector 1 , as schematically shown in FIGS. 9 and 10. At least one additional series of secondary reflective and/or refractive surfaces 7"' may be provided, on an area C of the cap 3, that is longitudinally offset to the first and second series 7', 7" of primary reflective surfaces and the corresponding areas A and B of the cap 3.

Conveniently, the secondary reflective and/or refrective surfaces 7"' may have a flat, conical or aspherical shape, that can be based on parametric or irregular functions and have a function that is complementary to that of the first two series to distribute light to areas of the target that are not sufficiently illuminated, thereby achieving a more uniform light emission from the projector 1.

FIG. 9 shows a second embodiment of the projector of the invention, which is similar to the first one, and basically differs therefrom in the arrangement of the light sources 6', 6".

In this case, the LEDs 6"' are of the same type as the series 6" of LEDs, namely they are located in the case 2 in such positions that at least one of the LEDs 6"' has its main axis of symmetry H'" unreflected by any one of the reflective surfaces of the cap 3.

The LEDs 6"' are arranged in arrays on pairs of boards 8"' along the opposite longitudinal edges of the cap 3 in longitudinally offset positions relative to the boards 8' with the light sources 6' thereon.

FIG. 10 shows a third embodiment of the projector, which is similar to the previous ones and basically differs therefrom in the shape and position of the secondary refractive surfaces 7"', here having a transverse extension and orientation to separate the light emissions of the series 6', 6"' of LEDs, thereby minimizing losses and optimizing the combination of their respective light beams. Generally, the reflective surfaces 7', 7" and the reflective and/or refractive surfaces 7"' are formed on or applied to the outer surface of the cap 3, preferably using plastic materials such as PMMA or polycarbonate type, with one or more layers of highly reflective metal materials laid thereon under high vacuum. Alternatively, the cap 3 may be formed with a metallic material selected from the group comprising pure aluminum (Al), alloys thereof (Alx), pre-treated steel and other highly reflective metal materials.

If plastic materials are used, the cap may be formed by injection of liquid- state material into a mold having a highly finished, low-roughness inner surface, with an average size of irregularities preferably but not necessarily falling in a range from 1 pm to 500 pm.

This roughness shall result from an optimal compromise between the needs for maximum light reflection and minimum heterogeneity of the projection on the target T. Then, high vacuum deposition of one or more layers of pure aluminum (Al), alloys thereof or other reflective metals, such as silver (Ag), is performed. Preferably, the amount of metal required for a single deposition is from 10^ to 10 grams. Possibly, high vacuum deposition of protection materials, such as quartz (SiO2) or magnesium difluoride (MgF₂), may be carried out.

If metallic materials are used, plates of such materials are used whose surface is treated to meet the most stringent optical requirements, such as the total percentage of reflected energy and predetermined values of Gaussian and Lambertian light diffusion.

Examples of such materials are, for instance, aluminum alloys (Alx), or stainless steel, or galvanized or chromated sheets. The cap 3 may be formed from metal materials by any method, such as cold molding, bending, thermoforming or other technologies, including die casting or injection molding. Preferably but not necessarily, bending and shearing techniques are used, with separate parts being assembled, which avoids the use of the known die casting or injection techniques which might affect the optical properties of the pre-treated material.

The pre-treated metal material may have either isotropic or anisotropic optical properties. Aluminum typically has a total reflectivity from 70% to 99%. Reflectivity is composed of a part of diffuse reflection, from 1 % to 98% of total reflectivity, and a part of specular reflection, from 1 % to 98% of total reflectivity.

The LEDs 6', 6", 6"' are powered by electric and/or electronic power and control units, not shown and easily available on the market.

An important aspect of the projector is the temperature at which the LEDs 6', 6", 6"' operate. Luminous efficiency of LEDs is known to decrease as the junction temperature T_j increases in the photoemissive materials of the LEDs at the p-n junction of the solid substrate.

For this purpose, heat sink means 9 are provided, which are used for heat dissipation, and preferably consist of sets of parallel cooling fins 10, which are thermally connected to the LEDs. For this purpose, the fins are integrally formed on or applied to the outer loadbearing case 2 and are directed radially outwards to be lapped by an air flow adapted to increase heat transfer by both conduction and convection.

Conveniently, the cooling fins 10 are designed to contact the electronic boards 8', 8", 8"' on which the LEDs are installed, to assist cooling thereof. Advantageously, the cooling fins 10 are formed from thermally conductive and low thermal resistivity materials, such as aluminum alloys (Alx) or steel, which may be die cast, and are thermally connected to the electronic boards, either directly or through thermal interface layers 11.

The material that forms the thermal interface layers 11 is selected from high conductivity, low thermal resistivity heat conducting materials, possibly having adhesive properties. Examples of such materials are the gap-pad material designated as "thin" 3000S30 or "ultra-thin" T-Gon 805-AO, both manufactured and sold by Bergquist or the mastic ThermalSeal^® sold by Excel Scientific Inc. and commonly used in the aeronautical and aerospace industries. The heat dissipation ability of the heat sink means 9 is obtained considering their ability to dissipate the heat produced in the device by the LED sources into the outside environment.

This ability is assessed by on-site measurements using thermocouples, complex thermal probes or Peltier cells at various locations of the surface of the electronic boards, which are placed at a distance of 0,5 to 5 mm from the solders of the LEDs or above such solders at least at 20 mm therefrom. If possible, temperature is sensed at various locations of the interface surfaces. However, the value T_j may be directly sensed on the junction surface.

Therefore, the junction temperature value T_j might be estimated using the relation of this temperature to the forward voltage V_f. Nevertheless, considering the difficulty of directly or indirectly detecting the voltage V_f at the ends of the LED in very short times, i.e. within the first 25 msec, the use of this relation is actually impossible. Alternatively, the temperature value T_j may be estimated with a good approximation and a mean error of about 5%, by using an indirect method that involves the determination of a ratio η = Er/En of the detected luminous efficiency to the nominal efficiency.

Once such value η has been obtained, it can be introduced into the y axis of the thermal decay curve delivered by the LED manufacturer, thereby obtaining the T_j value for the steady state device on the x axis.

If the T_j value of the projector is too high and unacceptably reduces the light flux, the heat sink-interface system may be modified, for instance by replacing one or more component materials or changing the thickness of the interface materials to reduce the heat resistance of the interfaces or the heat sink fins.

For sake of completeness, it should be noted that the front opening of the cap 3 may be covered with a substantially flat or appropriately shaped plate 12 of an optically transparent material, such as glass or PMMA, which is designed to protect the parts within the cap and to provide weather insulation (from water, moisture, wind, salt) and accidental impacts (stones, grail, etc.).

It should be noted that, although the plate 12 is formed from a base material whose maximum reflectivity is never greater than 0,1 , its inner surface is not deemed to be a reflective surface comparable with the reflective or reflecting and/or refractive surfaces 7', 7", 7"'. Therefore, the energy reflected from this inner surface shall be deemed to be irrelevant to the optical function of the projector 1 and will not substantially affect its operation and final optical properties. Possibly, the projector 1 may be equipped with additional refractive elements, not shown, such as lenses or meniscus elements for changing or adapting the optical performances of the reflective or reflecting and/or refractive surfaces 7', 7", T".

Possibly, these refractive elements may be interposed between at least one LED and at least one of said reflective or reflecting and/or refractive surfaces T, 7", 7"'.

Otherwise, the refractive optical elements are placed at the end of the optical path of the light emissions of the LED sources in the case 2.

The projector with LED sources of this invention is susceptible to a number of changes and variants, within the inventive concept disclosed in the appended claims. All the details thereof may be replaced by other technically equivalent parts, and the materials may vary depending on different needs, without departure from the scope of the invention.

While the projector has been described with particular reference to the accompanying figures, the numerals referred to in the disclosure and claims are only used for the sake of a better intelligibility of the invention and shall not be intended to limit the claimed scope in any manner.

Claims

1. A projector (1) with solid-state light sources (6) for street lighting or the like, comprising:

- an outer supporting case (2) having a longitudinal axis (L) and a transverse axis (W) in mutual orthogonal relationship, and defining a main extension plane (∑) and a pair of respectively longitudinal(Q)and transverse ( ^planes;

- a plurality of LED light sources (6', 6", 6"') and

- a cap (3) having an inner surface (7);

wherein each of said LED sources (6', 6", 6"') has a predetermined FWHM value and a main axis of said FWHM parameter (Η', H", H'"); and wherein said inner surface (7) of said cap (3) comprises a plurality of reflective surfaces (7', 7") for reflecting and/or refracting at least part of the emission of said LED sources (6', 6", 6"').

characterized in that said LED sources (6', 6", 6"') are in such an arrangement relative to said reflective surfaces (7', 7") that none of them is subjected to at least one total reflection of the whole light emission within its optical FWHM parameter, at least one of said LED sources (6") being oriented in such a manner that its main optical axis (H") is directed toward a target (T) without impinging upon none of said reflective surfaces (7', 7"), thereby reducing the number of reflections in the light emission that is comprised in the range of its optical FWHM parameter and maximizing the luminous efficacy of the projector (1).

2. Projector (1) as claimed in claim 1 , characterized in that said light sources (6) comprise at least one first series (6') of LEDs with respective axes of symmetry (Η') of the FWHM parameter reflected at least once by the reflective surfaces (7') of the cap (3), to mainly illuminate areas (T) of the target that are closer to the projector.

3. Projector (1) as claimed in claim 2, characterized in that the LEDs of said first series (6') are mounted to at least one pair of electronic boards (8') located in the proximity of the opposed longitudinal edges of said case (2) in positions substantially symmetrical with respect to said longitudinal vertical plane (Ω).

4. Projector (1) as claimed in claim 2, characterized in that said light sources (6) also comprise at least one second series (6") of LEDs which are so positioned and orientated that at least one of them has its main axis of symmetry (H") unreflected by the inner surface (7) of said cap (3).

5. Projector (1) as claimed in claim 2, characterized in that said inner surface (7) of said cap (3) comprises at least one first series of primary reflective surfaces (7') whose profile is substantially symmetrical with respect to a plane of symmetry (Ω) substantially perpendicular to said main extension plane (∑).

6. Projector (1) as claimed in claim 5, characterized in that the primary reflective surfaces (7') of said first series are mainly located in a first area (A) of said cap (3) substantially facing said first series (6') of LEDs.

7. Projector (1) as claimed in claim 6, characterized in that said primary reflective surfaces (7') of said first series have such orientation as to reflect the light emitted by said first series (6') of LEDs to an area (T) of the target that is closer to the projector.

8. Projector (1) as claimed in claim 2, characterized in that said inner surface (7) of said cap (3) comprises at least one second series (7") of primary reflective surfaces, which are mainly located in a second area (B) of the projector (1) and have such an orientation as to reflect light to an area (T") of the target that is farther from the projector.

9. Projector (1) as claimed in claim 7, characterized in that the primary surfaces (7") of said second series are mainly formed in a second area (B) of the projector (1) and have a shipe that is substantially asymmetrical with respect to said transverse vertical plane (Ψ).

10. Projector (1) as claimed in claims from 2 to 8, characterized in that said inner surface (7) of said cap (3) comprises at least one third series of secondary reflective and/or refractive surfaces (7"'), which are located on the cap (3) in an area (C) that is longitudinally offset to the first two areas (A, B), and to said first and second primary reflective surfaces (7', 7"), to distribute the light beam over insufficiently illuminated areas of the target and to ensure a uniform lighting profile.

11. Projector (1) as claimed in claims from 2 to 4, characterized in that it has heat sink means (9) for dissipating the heat generated by said

LEDs (6\ 6", 6"'), wherein said heat sink means comprise sets of parallel cooling fins (10) which extend radially outwards.

12. Projector (1) as claimed in claim 11 , characterized in that said cooling fins (19) are integral with said case (2) and are thermally connected to said LED for improved heat exchange.

13. Projector (1) as claimed in claim 11 , characterized in that said cooling fins (10) are placed in contact with the electronic boards (8', 8", 8"') on which the LEDs are installed, directly or with at least one thermal interface layer (11) interposed therebetween.

14. Projector (1) as claimed in claim 11 , characterized in that said cooling fins (10) are made of thermally conductive and low thermal resistivity materials, such as aluminum alloys (Alx), steel, ceramic materials.

15. Projector (1) as claimed in claim 11 , characterized in that said at least one thermal interface layer (11) is of high conductivity, low thermal resistivity materials, possibly having adhesive properties.

16. Projector (1) as claimed in one or more of claims from 5 to 10, characterized in that said reflective and/or refractive surfaces (7', 7", 7"') comprise at least one substrate of plastic materials selected from the group comprising PMMA and polycarbonate, or metal materials selected from the group comprising pure aluminum (Al), alloys thereof (Alx), isotropic or anisotropic pre-treated steel, and other highly reflective materials.

17. Projector (1) as claimed in claim 16, characterized in that one or more layers of highly reflective and/or refractive metal materials, selected from the group comprising pure aluminum (Al), silver (Ag) or alloys thereof, and possibly a final protective layer of materials selected from the group comprising quartz (Si02) and magnesium difluoride (MgF2) are deposited under high vacuum on said substrate.

18. Projector (1) as claimed in claim 16, characterized in that said cap (3) made of metal materials is obtained with a shaping method selected from the group comprising cold molding, bending, thermoforming, injection or die casting, or by assembly of separate parts obtained by bending and/or shearing.