A light source, for example for lighting surfaces Technical field

The present description relates to light sources.

Various embodiments may relate to light sources, of the LED type for example, which can be used for lighting surfaces.

Prior art

A solution known in the field of lighting technology, called "wall washing", is provided by the method shown schematically in Figure 1, namely by arranging for the surface S of a wall W (this term also covering a floor or a ceiling) to be lit by a source of light radiation RS which irradiates the surface S with a beam of light, thereby lighting it.

This solution may suffer from two fundamental drawbacks.

In the first place, unless accessories such as brackets, shelves, and the like are used, the light source RS can, in practice, be mounted only on a wall other than the wall W which is to be lit: for example, if the wall W is a side wall of a room, then in practice the light source RS can only be mounted on the ceiling or on the floor. Secondly, only a limited fraction of the light radiation emitted by the light source RS (indicated by UL and corresponding to the portion of the solid angle of emission of the source RS which includes the surface S) is used to light the surface S ; the remainder of the radiation, indicated by WL in Figure 1, is not used to light the surface S, and is wasted as far as this application is concerned.

The inventors have discovered that, as regards the first as- pect, it is possible to use shelves or brackets to support the light source RS : however, these would be additional elements which it would often be preferable to avoid, for reasons of cost and complexity of installation, and also because they may be intrusive in the environment in which they are installed.

The inventors have also observed that the fact that much of the radiation emitted by the light source RS does not reach the surface S can be remedied to some extent by mounting the light source RS on an orientable support such that the beam of light radiation from the source RS can be directed more satisfactorily onto the surface S: however, this solution leads to a non-uniform distribution of lighting on the surface S, whereas the desired wall washing effect usually re- quires lighting to be as uniform as possible.

Object and summary

The object of the invention is to overcome the aforesaid dis- advantages.

According to the invention, this object is achieved by means of a light source having the characteristics claimed in the claims below.

The claims form an integral part of the technical teachings provided herein in relation to the invention. Various embodiments can be used to obtain various advantages, in terms of the optical and mechanical aspects, and also in terms of simplicity and economy of manufacture. Regarding the optical aspects, various embodiments enable at least one of the following advantages to be obtained:

- uniformity of distribution of lighting on the lit surface, - optimization of the use of the light radiation: the light radiation produced by the radiation source is mostly used to irradiate the surface to be lit, thus making it possible to reduce the power, and therefore the absorption, of the light radiation source,

- flexibility in the design process, making it possible to obtain different results in terms of configuration of the radiation, for example by modifying one of the optical modules or stages included in various embodiments, and

- flexibility which is advantageous for the end user, in that the user can regulate the depth of irradiation of the lit surface according to his preferences and requirements. Regarding the mechanical aspects, possible advantages which can be obtained in various embodiments are as follows:

- the lighting device can be mounted at any height with respect to the surface to be lit, and it is possible to mount the source on the surface itself;

- it is possible to change selectively one or more of the stages included in the embodiments according to the desired lighting effects. Finally, regarding the simplicity and costs of production, various embodiments enable a plurality of functions to be integrated into a simple and compact optical system, making it possible to use, for example, optical components made of low- cost plastic material by a molding process.

Brief description of the drawings The invention will now be described, purely by way of non- limiting example, with reference to the appended drawings, of which :

- Figure 1 has been described above,

- Figure 2 is a perspective view of an embodiment,

- Figures 3 to 5 show various details of some embodiments, and

- Figure 6 shows the methods of operation of some embodiments .

Detailed description

The following description illustrates various specific details intended to provide a deeper understanding of the embodiments. The embodiments may be produced without one or more of the specific details, or may use other methods, com- ponents, materials, etc. In other cases, known structures, materials or operations are not shown or described in detail, in order to avoid obscuring various aspects of the embodiments . The reference to "an embodiment" in this description is intended to indicate that a particular configuration, structure or characteristic described in relation to the embodiment is included in at least one embodiment. Therefore, phrases such as "in an embodiment", which may be present in various parts of this description, do not necessarily refer to the same embodiment. Furthermore, specific formations, structures or characteristics may be combined in a suitable way in one or more embodiments.

The references used herein are purely for convenience and therefore do not define the scope of protection or the extent of the embodiments. In Figures 2 to 6, the reference numeral 10 indicates a lighting device which can be used to light a surface S according to the solution known as "wall washing" to which reference has already been made in the introductory part of the present description.

The device 10 can be used, for example, according to the principles illustrated schematically with reference to the light source RS in Figure 1, while overcoming the intrinsic drawbacks of this solution (such as the limitations regarding mounting, and the dispersion of much of the light radiation produced by the source and not used for the desired effect) .

In various embodiments, the device 10 can include, in addition to a light radiation source 12 (which can be formed, for example, by an LED light radiation source) , an optical system having three stages which can substantially be identified as follows : - a first optical stage 14, acting as a collimator of the radiation produced by the source 12,

- a second optical stage 16, having the function of deflect- ing the collimated radiation beam produced by the first stage

14 so as to direct it toward the surface S, and

- a third optical stage 18, which receives the beam deflected by the second optical stage 16 and distributes it spatially, for example in order to achieve an effect of uniform lighting of the surface S .

In various embodiments, the first stage (collimator stage) 14 can be constructed as shown schematically in Figure 3.

In various embodiments, the stage 14 can allow for the fact that the light radiation produced by a source such as an LED light source 12 is distributed with a light radiation pattern which can include: an "inner" (or central) portion concentrated about the principal axis of radiation X12 of the source 12, and

- an "outer" (or peripheral) portion distributed about the aforesaid principal axis X12.

In various embodiments, the stage 14 can have the function of concentrating the light radiation produced by the source 12, by collimating it along the axis X12.

Numerous possible embodiments of optical systems capable of providing this function are known: see, for example, the following documents: EP 2 180 232 Al , US 2008/198604 Al , WO 2006/131501 Al , US 2007/114551 Al , JP 2005 216 782 A, US 2006/050530 Al , US 5 939 996 and US 2008/074896 Al .

In various embodiments, the stage 14 can include:

- a portion 14a operating by refraction (in practice, a lens which can be produced in a wide range of possible known morphologies) , which acts on the inner portion of the emission beam of the source 12 to direct this inner portion of radia- tion along the axis X12, and/or

- a portion 14b operating by reflection (for example, a deflector produced in a wide range of possible known morphologies, such as a parabolic reflector), which is struck by the outer portion of the radiation beam emitted by the source 12 and acts by redirecting this outer portion of radiation along the axis X12.

The overall effect is to generate, from the radiation gener- ated by the source 12, a beam of light radiation which is completely collimated, or has a reduced residual divergence, this beam being indicated as a whole by LC .

The collimated beam LC is sent toward the second optical stage 16 which includes, for example, a reflective surface. In various embodiments, the reflective surface in question can be formed by one of the faces of a prism structure 20, for example a prism of transparent material such as a transparent thermoplastic material, which has (see, in particular, Figure 4) :

- an input surface 20a through which the collimated radiation beam LC enters the prism structure 20 and is then reflected from the reflective surface 16; - a face 20b of the prism 20 which forms the reflective surface 16 and which, when acting as the second optical stage, can receive the collimated beam LC entering through the input surface 20a and deflect it, in the form of a deflected beam LD, toward a third face of the prism, indicated by 20c,·

- the aforesaid third face 20c of the prism 20 forming the third optical stage 18 which, acting on the beam LD deflected by the second optical stage 16, distributes or "spreads" the deflected beam, thus creating a spread beam (indicated by LS in Figures 4 and 6) which is intended to strike the surface S . In various embodiments, advantages in terms of overall compactness can be gained by incorporating the second optical stage 16 and the third optical stage 18 into a single structure . In various embodiments, the prism 20 can be made either as a solid structure or as a hollow structure, for example in the form of a bowl-shaped body in which the surface 20a is the input aperture and the walls 20b and 20c are two side walls. Regarding the formation of the surface 16 intended to deflect the collimated beam LC in order to create the beam LD sent toward the third optical stage, it is possible either to use a surface which is made reflective by a coating treatment, for example an aluminum coating treatment, or to use (in the case in which the prism 20 is a solid structure of transparent material, for example) a method which can impart TIR (Total Internal Reflection) characteristics to the surface 16, without the need to use a reflective coating such as an aluminum coating. In various embodiments, the deflection geometry described by way of example herein with reference to the stage 16 can have different characteristics from those described herein, for example characteristics such that deflection can be provided at an angle other than the angle of 90° illustrated by way of example in the drawings .

In particular, it is possible to obtain deflection angles such that the collimated beam LC and the deflected beam LD form an acute angle (in other words, an angle of less than 90°) between them, thereby enabling the device 10 to be mounted on the surface S which is to be lit. Figure 2 (together with Figure 5, which can be seen substantially as a view from above of the solution shown in Figure 2) clearly shows that, in various embodiments, the third optical stage 18, which is intended to diffuse or spread the deflected beam LD so as to create the spread beam LS, can use bar-like lenses 180 adjacent to each other in an array of lens elements which extend in a direction approximately orthogonal to the input surface 20a of the structure 20.

The output surface 20c of said third optical stage 18 has a rectangular shape which is helpful if a rectangular area is to be lit.

In some embodiments (as shown more fully in Figures 2 and 4) , the aforesaid bar-like lenses 180 can have a curved configu- ration in order to provide not only a modeling or shaping which is "horizontal" (in other words, in a first direction), as shown schematically in Figure 6, but also a modeling effect in a "vertical" direction (in other words, in a second direction) . ₁

In various embodiments, the first modeling effect can be spreading for the purpose of distributing the beam LS along the sides of the device 10.

In various embodiments, the second modeling effect can be intended for modeling the beam LS (by narrowing it if necessary, as shown schematically in Figure 4), in order to obtain a substantially uniform intensity not only on the parts of the surface S closer to the device 10, but also on the parts of the surface S which are more remote from the device 10.

Various embodiments can also offer a wide range of possibilities for varying the characteristics of the stage 18 in order to modify the effect of spreading and/or narrowing the beam LS according to the user's requirements.

For example, although the introductory part of the present description refers to the aim of achieving an effect of irra- diation or "washing" of the surface S which is as uniform as possible in terms of lighting intensity, various embodiments allow the distribution of the lighting to be varied. In all cases, these arrangements overcome the intrinsic limitations of the solutions referred to in the introductory part of the present description, which in practice are constrained by an intrinsically non-uniform distribution of the lighting, wherein the portions of the surface S closer to the source RS are inevitably lit in a less intense manner than the more remote portions.

Various embodiments allow the distribution of the lighting of the surface S to be modified as desired, making it possible to change, for example, from a uniform distribution to a lighting distribution in which the parts of the surface S more remote from the device 10 are lit less intensely than the closer portions, with a wide range of possible intermediate solutions. The aforesaid modification methods for the purpose of obtaining possible desired effects of focusing the light radiation beam can be carried out not only at the third stage 18 but also at the other two optical stages 14 and 16, thus considerably enhancing the flexibility of the device.

An additional degree of flexibility can be achieved by modifying not only the optical systems described herein (the lenses and/or reflectors, in other words the active parts of the optical system) but also the supports of these parts, thus enabling the active parts to be made interchangeable if necessary within a single support structure, in such a way that different lighting effects can be achieved while using the same support structure, according to the user's requirements .

Naturally, the principle of the invention remaining the same, the details of construction and the forms of embodiment may be varied, to a greater or lesser degree, with respect to those illustrated, which have been given purely by way of non-limiting example, without thereby departing from the scope of protection of the invention or the scope of production as defined in the attached claims.