The present invention relates to a modular reflective optical lighting system, and a lighting device equipped therewith, in particular a vehicle light or headlight, wherein the desired brightness distribution is achieved, among other things, by juxtaposing inside a single body two or more modular optical systems comprising the same "basic" components, the latter being more or less identical to one another.

It is known that the lighting devices used in vehicles, especially motor vehicles, are required to perform increasingly complex and demanding functions, for example daytime lighting, or DRL (the Daytime Running Light function) and progressive illumination of bends (cornering) while at the same time they must be smaller in size, in order to reduce their overall dimensions and weight. One solution offered by modern technology consists for example of using solid-state light sources or LEDs, which reduce both the amount of energy that is used and the amount of heat that is generated during their use, which is one of the greatest limits of traditional incandescent light sources (bulbs).

WO2007069123 for example relates to a vehicle dipped-beam headlight that is provided with a solid-state light source (LED).

Here and in the following description, the term "light source" refers to any light source (LED, incandescent lamp, discharge lamp, etc.) in which the light rays that are emitted can be approximated as ideally radiating from a single point, for example, in case of incandescent lamps, from the middle of the filament. This definition therefore excludes light sources such as neon tubes, in which the light rays are radiated from a plurality of adjacent points arranged along an axis.

The headlight described in WO2007069123, while using a LED as the light source, is relatively large and complex, due to the need to overcome a series of practical design problems associated with the use of a single solid-state light source that is sufficiently powerful to achieve the brightness distribution required by a headlight.

DE19820267 describes a reflective optical lighting system that uses a LED light source and achieves uniform distribution of the emitted light in a system with limited overall dimensions; said optical system is based on the connection of the light source with a reflector consisting of a convex element the convexity of which lies in the main direction of emission of the light source; the convex element can consist of a curved surface or of two reflecting surfaces of any shape (flat, concave or convex) joined together at an angle. This type of optical system, conceived for the rear illumination of a display, for example a liquid crystal display, can in theory also be used for vehicle lighting devices, but in that case its use would clearly be limited to lamps only.

The purpose of the present invention is therefore to provide a reflective optical lighting system with reduced overall dimensions that is suitable to use light sources consisting of LEDs, as in the case of the optical system described in DE19820267, but which is more versatile and in particular can be used indifferently to produce lamps and headlights and can therefore be used in the manufacture of indicator and lighting devices for vehicles that are cheap to produce, light in weight, have reduced overall dimensions and low electricity consumption, possibly with a single device incorporating a multitude of different optical functions, thus overcoming the limits of the prior art. DE102004025699 does not solve this problem.

According to the present invention a reflective optical system is provided as set forth in claim 1.

In particular, the reflective optical lighting system according to the invention comprises at least one light source having a first optical axis defining a main direction of radiation of light rays emitted by said source and at least a first and a second reflecting surface operationally associated with the light source to intercept the light rays and arranged so as to form between them a first pre-defined angle of a size other than 180°; unlike in DE19820267, however, the first and second reflecting surfaces delimit, between them, a concavity oriented towards the light source and are shaped so that, when in use, said concavity receives a substantial portion of said light rays emitted by the source to reflect them in a direction forming with the first optical axis a second angle of a pre-defined size, so that the reflected rays present a main direction of radiation defined by a second optical axis essentially perpendicular to the first.

The light source that is used is a Lambertian light source and in that case the concavity defined between the first and the second reflecting surfaces and oriented towards the light source occupies a solid angle greater than π steradians, i.e. greater than a quarter of the solid spherical angle, and in any case such that at least 30% of the light rays emitted by the source are intercepted by the first and second reflecting surfaces.

The optical system according to the invention can also comprise at least one bright, clear or coloured secondary optical element, operationally associated with the first and second reflecting surfaces in the direction defined by the second optical axis and consisting of at least a lens or a matrix of micro-optics arranged transversely to the second optical axis.

Lastly, the optical system according to the invention can comprise a plurality of light sources, each operationally associated with a first and second reflecting surface to form therewith a single lighting module so that said system consists of a plurality of lighting modules mutually juxtaposed in a one-dimensional or two-dimensional matrix arrangement.

The invention also relates to a lighting device comprising a cup-shaped element, preferably made of plastic or metal and fixable to the body of a vehicle, and at least a transparent fluid-tight sealing element to close an opening in the cup-shaped element in which said optical system is arranged and housed in a position oriented towards the opening and such that the second optical axis intercepts the transparent closing element and when used is directly parallel to a direction in which the vehicle is travelling.

Thus, a similar process can be used to produce both headlights (in particular those intrinsically incorporating a bright-dark or cut-off line such as main-beam headlights or fog lights, in which the light source, in particular a LED light source, is assembled face-down - hereinafter referred to as DLA, for "Down LED Assembly" - so that the parasite rays illuminate the road and are not dispersed upwards), and indicator lights (position or direction indicators, etc.)

It is also possible to produce lighting devices that consist of a single "basic" optical module, comprising a light source and the two reflecting surfaces associated therewith joined at an angle of approximately 90° depending on the desired brightness distribution (symmetric or asymmetric). A "basic" module can be connected vertically or horizontally to one or more identical or similar modules, in order to obtain a complex system, which allows the use of particular types of activation logic, for example to activate the different modules gradually as a function of the steering angle of the vehicle (the "Static Bend Lighting" function).

The light sources can be incandescent lamps or solid-state sources (LEDs). The LEDs can be SMDs (Surface Mounted Devices) or dies (semiconductors only), possibly in a matrix arrangement. If several chips are used in the same basic module for example, different coloured lights can be obtained, using the same pair of angled reflecting surfaces for different functions, by appropriately mixing the contributions deriving from different monochromatic LED sources. For example, using RGB (Red Green Blue) LEDs, the same function can be used for the direction indicator, DRL and particular sectors of the dipped-beam / main-beam functions.

Possible fields of application for the present invention are therefore headlights or lamps for cars, both to implement indicator functions (direction indicators, DRL, position indicators, side markers) and lighting functions (dipped-beam, main-beam, fog lights, SBL).

Further characteristics and advantages of the present invention will become clear from the following description of the non-limiting embodiments thereof, with reference to the drawings attached hereto, in which:

• figure 1a schematically illustrates a front three-quarter perspective view of the structure of a "basic" optical system according to the present invention;
• figure 1b shows the same view as figure 1a, but in case of a complex optical system, consisting of several juxtaposed modules each consisting of a "basic" system;
• figure 2 shows the same view as figure 1a in case of a "basic" indirect or "remote" lighting system;
• figures 3a and 3b schematically illustrate possible alternative configurations of the "basic" system in figure 1a and the relative symmetric or asymmetric brightness distribution that can be obtained on a screen 10 m away in the standard photometric test;
• figures 4a and 4b are schematic orthogonal elevations of two alternative embodiments of the luminous source of the optical system according to the invention;
• figure 5 is an elevation and longitudinal section view along the optical axis of the basic optical system in figure 1a; and
• figure 6 illustrates a front three-quarter perspective view of a vehicle headlight incorporating an optical lighting system according to the invention.

With reference to figure 1a, reference number 1 indicates a reflective optical lighting system comprising at least one light source 2 and at least a first reflecting surface 3 and a second reflecting surface 4 operationally associated with the light source 2 and arranged obliquely in relation to one another; in particular, the light source 2 has a first optical axis A defining a main direction of radiation of light rays R emitted by said source 2 and the reflecting surfaces 3 and 4, which may be flat, concave or convex and can be defined by a single equation or by a complex series of equations, are oriented with respect to the axis A to intercept the light rays R and are in particular arranged to form between them a preset first angle β of a size other than 180°.

According to a first and fundamental aspect of the invention, the reflecting surfaces 3 and 4 between them delimit a concavity 5 oriented towards the light source 2 and are shaped so that when in use said concavity 5 receives a substantial portion of the light rays R emitted by the source 2 to reflect them in a direction forming with the optical axis A an angle α (figure 5) of a preset size, so that the reflected rays r present a main direction of radiation defined by a second optical axis B, essentially perpendicular to the optical axis A.

According to the invention, the angle β between the two reflecting surfaces 3,4 arranged obliquely in relation to one another is 90° or in the region of 90°, for example (figures 3a and 3b) said angle is respectively less than 90° (figure 3b) or more than 90° (figure 3a), thus achieving a respectively asymmetric and symmetric brightness distribution of the reflected rays r with respect to the optical axis B.

With reference to figure 5, the size of the angle α can be between 50° and 150° and, more preferably, it is between the values α1 of 85° and α2 of 100°. Moreover, the reflective optical system 1 described herein preferably comprises, for each first and second reflecting surface 3 and 4, associated with a single light source 2, at least a third reflecting surface 10 (figure 5) and/or 11 (figure 1a) oriented towards the concavity 5 and in any case arranged essentially perpendicularly to the optical axis A, in order to also produce in the direction defined by the optical axis B reflected rays r' (figure 5) which have undergone a double reflection, for example so as to send almost all of the light rays R emitted by the source 2 below a bright-dark cut-off mark L (figure 3).

The light source 2 is a Lambertian light source and the concavity 5 defined between the reflecting surfaces 3 and 4 and oriented towards the light source 2 occupies a solid angle greater than π steradians, i.e. greater than a quarter of the solid spherical angle, and in any case such that at least 30% of the light rays R emitted by the source 2 are intercepted by the reflecting surfaces 3,4 and re-directed as rays r (or r').

Lastly, the optical system 1 described herein can also comprise (figure 1a) at least one bright, clear or coloured secondary optical element 20, operationally associated with the reflecting surfaces 3,4 in the direction defined by the second optical axis B and consisting of at least a lens or a matrix of micro-optics 21 arranged transversely to the axis B.

According to the possible and preferred embodiment illustrated in figure 1b, a reflective optical system 100 according to the invention can be achieved by combining several "elementary" optical systems 1, which can be identical or not to one another.

In particular, figure 1b shows a reflective optical system 100 of the "complex" type comprising a plurality of light sources 2a,2b,2c, each operationally associated with a first reflecting surface, respectively 3a,3b,3c and with a second reflecting surface 4a,4b,4c, to form therewith a single lighting "module" 1a,1b,1c, so that the optical system 100 is made up of a plurality of lighting modules 1a,1b,1c, mutually juxtaposed in a mono-dimensional matrix arrangement (i.e. along an axis X or an axis Y only of a three-dimensional orthogonal reference system X,Y,Z, in which the axis Z is oriented so as to be parallel to the optical axis B - pairs 1a,1c or 1a,1b, respectively), or even a two-dimensional matrix arrangement (i.e. along both the axes X and Y - matrix 1a,1b,1c).

Clearly, in that case, the reflecting surfaces 3a,b,c, and 4a,b,c can be identical or, generally, not identical but with different equations and shapes, depending on the desired brightness distribution, and, likewise, the angles β1 and β2 can be identical or different.

In all cases, the sources 2 that are used comprise photoemitting means 30 selected from the group comprising: incandescent lamps; gas discharge lamps; monochromatic LEDs; polychromatic LEDs; and preferably consist of LEDs 30 suitable to emit a luminous flux of at least 10 lumens for a white light LED and 3 lumens for a red or orange light LED, mounted on at least one printed circuit board 31.

According to a further alternative embodiment of the invention, instead of consisting of one or more "basic" modules 1 possibly connected in a matrix arrangement, as illustrated in figure 1b, it can consist of one or more "basic" modules 200 (figure 2), in which the reflecting surfaces 3 and 4 which are arranged obliquely in relation to one another at an angle (3 such as to subtend a concavity 5 delimited between said surfaces 3 and 4, are associated with a light source 202 comprising photoemitting means such as a LED 30 borne by a relative printed circuit board 31 and a light guide 203 (for example consisting of a fiber optic or a fiber optic bundle), of which a first end 204 is arranged on a axis with the optical axis A and of which a second end 205 is arranged remotely in relation to the first and is connected to the photoemitting means 30.

The "basic modules" or systems 200 can of course also be connected to one another (or to basic modules 1) to form complex systems of the type of system 100 in figure 1b.

With reference to figure 6, one or more reflective optical systems 1, 100 and/or 200 can be incorporated into a lighting device 400 generally comprising an element 401 made of a synthetic plastic material or metal and fixable in a known way to the body of a vehicle (or to the inside of the body of a headlight), for example a motor vehicle which is not illustrated for the sake of simplicity, and at least one transparent fluid-tight sealing element 402 to close an opening 404 of the cup-shaped element 401, in which the optical system 1 and/or 100 and/or 200 is arranged and housed inside the cup-shaped element 401 in a position oriented towards the opening 404 and such that the optical axis B intercepts the transparent closing element 402 and when in use is directly parallel to a direction in which the vehicle is travelling.

Depending on the type of optical system 1, 100, or 200 that is used, the printed circuit board 31 is provided, on-board, with a single LED 30 (figure 4a) or with a plurality of LEDs 30b,30c,30d (figure 4b) which are possibly selectively activatable; in any case the printed circuit board 31 is attached to a mounting surface 405 of the cup-shaped element 401, which is generally obtained on a side wall, preferably an upper wall 406 of said cup-shaped element 401 and so that the first optical axis A is arranged perpendicularly to the mounting surface 405 (clearly, in case of the system 200, an optical axis C of the LED 30 is perpendicular to the mounting surface 405).

Moreover, according to an alternative and preferred embodiment, (figure 4) the generic light source 2 (or 202) also comprises electronic control means 500, preferably mounted directly on-board the printed circuit board 31, suitable to selectively activate/deactivate the single LED 30 (in case of the source 2 - figure 4a) or one LED 30b,30c,30d at a time (in case of a source 2' - figure 4b) of said plurality of selectively activatable LEDs 30.

In particular, the light source 2,2',202 is produced in such a way that said first and second surfaces 3,4 of a "basic module" 1 or 200 can be operationally associated, selectively, with different LEDs, for example 30b,30c,30d; and in such a way that, in case of a lighting device 400 such as that illustrated in figure 6, in which a single cup-shaped element 401 contains a plurality of first and second surfaces, respectively 3a,3b and 4a,4b, each operationally associated with a different LED 30a,30b, each LED 30 can be selectively activated according to a previously defined sequence. In the example illustrated in figure 6, the device 400 is a headlight and, in this case, the association of a pair of basic optical systems 1a,1b in a single element 401 with suitable electronic control means 500 is used to progressively illuminate different angular sectors (for example of a bend in the road) in relation to the direction in which the vehicle is travelling (SBL function).

The gradual activation or deactivation of the lighting element and the possibility of obtaining different brightness levels can also be achieved by using a PWM signal to modulate the current absorbed by the lighting module.

Clearly, on the basis of the description herein, it is possible to produce lighting devices of the type of the device 400, but which are multifunction devices, capable of being used indifferently as headlights or lamps (for example rear lights), depending on the shape and position of the pairs of reflecting surfaces arranged at an oblique angle in relation to one another that are used each time in association with a single LED (or a plurality or battery of LEDs mounted adjacently on a single printed circuit board, as in figure 4b).

According to a final but equally important characteristic of the invention, the printed circuit board 31 is in all versions of the system 1, 100, 200 associated with heat dissipation means 550 (figure 6), preferably mounted on the outside, for example above and to the rear, of the cup-shaped element 401.

In particular the LEDs 30 are preferably mounted "face-down" or in a DLA arrangement, as schematically illustrated in figures 4a and 4b, in which the printed circuit board 31 is mounted on an upper side surface 406 of the cup-shaped element 401, with the single LED 30 or battery of LEDs 30b,30c,30d face-down and so as in any case to distribute brightness with a bright-dark cut-off line L, as illustrated in figure 3; in this way the optical system according to the invention is used to perform functions that require a well-defined cut-off line, such as dipped-beam headlights or fog lights, or with a dual function (dipped-beam and fog lights).

Said "face-down" or DLA arrangement of the LEDs 30 also means that the optical system according to the invention can be used with the printed circuit board 31 mounted on the upper side surface 406 of the cup-shaped element 401, with the single LED 30 or battery of LEDs 30b,30c,30d face-down and associated with heat dissipation means 550 arranged on the rear of the cup-shaped element 401 and directly connected to at least one component element 560 (figure 4) of the printed circuit board 31 made of a material with relatively high thermal conductivity.

In particular, the "face-down" or DLA arrangement of the LEDs 30 makes it possible to obtain a better thermal coupling between the printed circuit board 31 and the passive dissipation element 550, when the printed circuit board 31 is produced with an appropriate layout (single face), said thermal coupling comprising conductive tracks 562 on which the dissipation part of the LEDs 30 is mounted and which are attached to an aluminium base 565, with an intermediate heat conducting layer 566 in the form of tape or liquid adhesive, whether the passive dissipation element 550 is arranged close to (figure 4b) or at a distance from (figure 4a) the tracks 562; the dissipation element 550 can be a specific, finned element, as in figure 6, or (alternatively or in addition) it can be said reflector 600 (figure 6) consisting of a single piece (or several pieces assembled together).

A lighting device according to the invention, such as the device 400, is thus characterized by the presence of at least one reflector the whole of which is oriented towards a transparent closing element 402, which may or may not have optical functions and is possibly provided with an intermediate auxiliary optical element 20, divided along at least a meridian thereof and by means of at least one edge in at least a pair of adjacent reflecting surfaces arranged at an oblique angle in relation to one another so as to between them delimit a dihedral angle and having a structure such as to define an optical axis B of the reflector arranged essentially perpendicularly to a plane through which the optical axis (A) of the light source used each time passes.

On the basis of the description herein, there is no need to use printed circuit boards with high thermal properties even for the electronic power components, in particular LEDs. Any control electronics (such as the control means 500) can be mounted on the printed circuit board 31 on which the LEDs are mounted, in order to implement a highly compact plug&play system.

In conclusion, the system according to the invention is characterized by the following elements:

• the optical axis A of the sources used is perpendicular to the mounting surface 405 of the printed circuit board 31, which forms an angle of between α1 (50°) and α2 (150°), in particular between 85° and 100°, in relation to the main direction (B) of emission of the reflector;
• the coupling between the passive heat dissipation element 550 and the weld side of the printed circuit board 31, on which the LED sources are mounted, which allows low-cost power LEDs and printed circuit boards to be used (such as the single-face type in FR4, CEM, etc,).