WO2017154031A2

WO2017154031A2 - Optical system for led lighting equipment

Info

Publication number: WO2017154031A2
Application number: PCT/IT2017/000038
Authority: WO
Inventors: Gian Pietro Beghelli
Original assignee: Beghelli S.P.A.
Priority date: 2016-03-11
Filing date: 2017-02-27
Publication date: 2017-09-14
Also published as: WO2017154031A3; ITUA20161518A1

Abstract

A LED (12) lighting appliance (15), comprising an optical system with refracted and diffused light, characterized in that said optical system includes at least one refractive element (10), made of transparent material and constitute of one or more lenses (11) positioned in correspondence to the respective LEDs (12), and at least one diffusive element, constituted by a superficial portion (20, 30) made of a diffusing material preferably at high reflectance, said superficial portion (20, 30) being placed in close proximity to said refractive element, in a way to obtain a photometric emission output at high visual comfort for the user, together at a high efficiency.

Description

7 000038

OPTICAL SYSTEM FOR LED LIGHTING EQUIPMENT

The present invention refers generally to an optical system for LED lighting appliances and, in specific, to a refracted and diffused light optical system for lighting appliances and luminous sources of LED type.

More in particular, the invention relates to the relation in an optical system of a refractive element (lens or system composed of multiple lenses) and of a diffusive element (flat or concave or convex surface) which allows to obtain, with luminous sources substantially point (preferably LED), the photometric emission (i.e. the light intensity distribution output) necessary for the illumination of work places with a high visual comfort for the user, in such a way that it illuminates the surface completely of the appliance, with the consequent secondary component diffused in the photometric emission, and avoiding the presence of dark zone environment in the vicinity of areas of high luminosity, potential cause of glare.

This result is achieved in the present invention without significantly reducing the efficiency of the appliance, as normally happens in devices that want to achieve similar results.

The most frequent installation of the lighting appliance, which is the object of the present invention, include, but not in an exclusive form, installations to "recessed" in modular ceilings and installations in suspended ceiling or mounted (with varying heights but mainly about 3 meters above the ground).

In the lighting sector, large number of constructive solutions for the planning and to the realization of refractive and / or reflective systems and / or diffusive adapted to be coupled to light sources of LED type, with the intent to obtain a comfortable lighting are already been proposed.

In particular, diffusive panels are often used, which provide a wide and homogeneous emitting surface in a substantial Lambertian distribution; these hide the direct vision of the LEDs and thus avoid the presence on the product surface of circumscribed areas (in correspondence of the single LEDs) from which originates a high luminance.

These solutions, however, are inevitably inefficient since the use of diffusive materials, do not allow to optimize the ratio of lighting performance / consumption.

The object of the present invention is, therefore, to provide one or more illuminating apparatus for emission controlled photometric and specifically addressed in space, so as to allow the realization of installations with high visual comfort together with a high efficiency, in compliance with the requirements of the service (with particular reference to regulations in force) for the illumination of work places.

Another object of the invention is to develop a lighting appliance for the emission of controlled photometric with easy and cheap to produce, without the use of complex and / or expensive technologies.

These and other objects, which will become apparent in more detail below, are achieved by a LED lighting appliance according to claim 1 attached hereto; more detailed characteristics of the lighting appliance according to the invention are reported in the corresponding dependent claims.

In an advantageous way, the LED lighting appliance according to the invention includes an optical system equipped with a refractive element (lens or system of more lenses) and of a diffusive element (diffusing plane or concave or convex diffusing surface), suitable to obtain a photometric emission, that is, a light intensity distribution in the space, necessary for the illumination of the places with a high visual comfort for the user together with a high efficiency.

The LED lighting appliance of the present invention can be flush-mounted in the ceiling, as well as in suspension or in mounted ceiling (about 3 meters in height).

Further characteristics and advantages of the invention will become apparent from the description of a preferred, but not exclusive, of the appliance of LED lighting, according to the present invention, illustrated only by way of non-limiting example, and from the accompanying drawings, in wherein:

- Figures 1 , 2 and 3 represent the same set of perspective views of three examples of embodiment of a LED lighting appliance with an optical system, according to the present invention;

- Figure 4 shows a perspective view of an enlarged portion of the optical system employed in the LED lighting appliance, according to the present invention;

- Figure 5 shows a top view of an enlarged detail of the optical system employed in the LED lighting appliance, according to the present invention;

- Figure 6 shows a cross section of one of the lenses used in the optical system of the lighting appliance of Figure 2, according to the present invention.

- Figure 7 shows a cross section of a single lens, according to the present invention, with two-dimensional ray-tracing in the section.

With reference to the mentioned figures, the lighting appliance 15 according to the present invention consists of a refractive element 10 made of a transparent material, that allows to obtain the photometric emission desired and its neighboring surfaces, of a form horizontally flat 20 or inclined 30, which represents the secondary illumination source.

The refractive element 10 is constituted by the composition of a right number of elementary lenses 11 , positioned in correspondence with an equal number of LEDs 12; the lenses 11 are arranged in one or more rows (two rows in the case of the particular application shown in Figures 1 and 2 attached, three rows in the case of the application shown in Figure 3 attached).

Each of the lenses 11 present a central zone 111 , corresponding to the emission of the LED 12 in the axis up to angles of approximately 60° and dedicated to formation of primary photometric emission of the appliance, that provides the desired luminance on the useful surface and in the area of the visual test, and an external lateral zone 112, corresponding to the emission of the LED 12 at large angles (>60°), useful to voluntarily directing residual part of the LED 12 flux corresponding, so as to contribute to the luminance, preferably uniform, of a superficial portion 20, 30 of the lighting appliance 15, more or less broad and level (horizontal or inclined), of diffusing material preferably at high reflectance.

The external lateral zone 112 of each lens 11 allows to illuminate the superficial portion 20, 30 of the lighting appliance 15 not interested from the obstruction of the lens 11 and more or less extends depending on the size of the lighting appliance 15; in this way, the effect is double.

Firstly, the illuminated area in the appliance 15 is not only that of the refractive optical component, but extends to the entire surface of the appliance 15, comprising the secondary emission surface formed from the group peripheral of lenses 11.

The light radiant of this area allows to reduce the effect of direct glare due to high luminance contrasts.

Secondly, the ulterior effect of the external lateral zone 112 of lenses 11 is to create in the distribution of outgoing radiation from the appliance, in addition to the component for the effective lighting of the visual test (generated by the central parts 111 of the lenses 11 ), also a secondary component of diffused light that improves visual comfort, always in compliance with current regulations.

The shape of the lenses 11 and the distance between the one and the other are designed in order to obtain on the portion 20, 30 of the lighting appliance a uniform illuminance along the longitudinal axis X of the optical system (compared to the development of rows of lens 11).

In the case in which the external surface to the optical system is plain and designed to reduce at most the overall thickness of the appliance 15 (also below 20 mm, including the dimensions of the lens 11), can also be necessary that the illuminance on the plain part 20 decreases from the center to the edges of the appliance 15, along the Y axis, which results perpendicular to the X axis and the rows of lenses 11 of the optical system; this uneven progress may be needed to comply with the limits prescribed by the regulations on the average luminance over 65°.

In case there are no requirement on minimum thickness and it's possible to embed the optical system in the lighting appliance 15 and shaping the remaining surface with a certain concavity, with an appropriate design of the external lateral zone 112 of the lenses 11 is possible to uniformly illuminate the external zone to the refractive optical system also along the Y-axis, counting, for the respect of limits of luminance, on the shield at large angles by the appliance 15 itself.

The superficial portion 20, 30 of the appliance 15 illuminated from the lateral zone 112 of the lenses 11 and of the form, preferably, but not exclusively, flat, and also concave or convex, with diffusing characteristics due to the surface finish (preferably white with high reflectance); in this way, it creates a diffused secondary photometric emission that contributes to visual comfort.

The refractive element 10 has an external lateral part 112 of the lenses 1 that compose it, which is studied to refract the radiation of the LEDs, incident on it, on the superficial portion 20, 30; the lenses 11 are placed side by side to each other in the central zone of the lighting appliance on one or more rows, as in the particular embodiment described herein, or they can be arranged according to other possible geometries.

In the particular embodiment described here the central zone 111 of each lens 11 has been segmented as a Fresnel lens and also the lateral zone 12 of the lenses 11 have been fragmented with the same criteria of Fresnel to reduce the thickness of the refractive component and maintain the variation of the thickness within the necessary limits for the realization of the mold of the refractive component.

In figure 6 attached, a schematic section of each lens 11 is shown with the indication of the useful Fresnel surfaces 13, 14 respectively to the central zone 111 and to the lateral or external zone 112 of the lens 11 ; the origin of the rays can be viewed in the optical center 110.

Some surfaces of the optical system not optically useful, that is not employed in the formation of the primary optical beam (central) nor of the secondary (diffuse), can be satin to scatter light and appear illuminated, so that it creates an illuminance in the background of surface of the optical system between lens and lens and the luminance is as possible as much uniformly distributed over the entire surface of the lighting appliance 15, avoiding dark zones and further improving comfort.

One of the advantages of a solution such as that described in the present invention is to obtain a high efficiency of the lighting appliance 15, since the central part or zone 111 of the lenses 11 , which affects the major part of LEDs 12 emission and that it is responsible for illuminance, is constituted by only two refractive interfaces; also the remaining light of the LEDs 12, conveyed on the diffusing surface of the appliance 15, can be diffused with a high reflectance with the use of appropriate diffusing material, maintaining high efficiency.

The radiation generated by reflections at refractive interfaces, which can not be controlled, is also partly recovered; in fact, it is guided by the refractive optical element in its internal due to the total internal reflection and / or is diffused by the diffusing surface which also extends also below the refractive optical element with the effect to contribute also to render more uniform the distribution of the luminance in the lighting appliance 15. The invention thus conceived is susceptible to numerous modifications and variants, all falling within the protective scope of the appended claims. Moreover, all the details may be replaced with other technically equivalent elements. In practice, the materials employed, as well as the shapes and the dimensions, may be varied depending on the contingent requirements and state of the art.

Where the constructional characteristics and techniques mentioned in the following claims are followed by reference signs or numbers, such signs and reference numbers have been applied with the sole purpose of increasing the intelligibility of the claims and consequently, they do not constitute in any way limiting the interpretation of each element identified, purely by way of example, by such signs and reference numbers.

Claims

1. A LED (12) lighting appliance (15), comprising an optical system with refracted and diffused light, characterized in that said optical system includes at least one refractive element (10), made of transparent material and constitute of one or more lenses (11) positioned in correspondence to the respective LEDs (12), and at least one diffusive element, constituted by a superficial portion (20, 30) made of a diffusing material preferably at high reflectance, said superficial portion (20, 30) being placed in close proximity to said refractive element, in a way to obtain a photometric emission output at high visual comfort for the user, together at a high efficiency.

2. A LED (12) lighting appliance (15) as claimed in claim 1 , characterized in that said superficial portion (20, 30) is flat and horizontal or inclined, or concave or convex.

3. A LED (12) lighting appliance (15) as claimed in at least one of the preceding claims, characterized in that said appliance (15) is recessed into modular ceilings, as well as in ceiling or suspended ceiling.

4. A LED (12) lighting appliance (15) as claimed in at least one of the preceding claims, characterized in that each of said lenses (11) has a central zone (111), corresponding to the luminous emission of said respective LED (12) in axis and up to emission angles of about 60°, which forms the primary component of the photometric emission of said appliance, and an external lateral zone (112), corresponding to the luminous emission of said respective LED (12) at emission angles greater than about 60°, that deflects the light on said superficial portion (20,30), contributing to the formation of the diffused secondary component of the photometric emission of the appliance.

5. A LED (12) lighting appliance (15) as claimed in claim 4, characterized in that said lenses (11) are arranged in one or more rows, adjacent or spaced apart.

6. A LED (12) lighting appliance (15) as claimed in claim 5, characterized in that said external lateral zone (112) allows to obtain an uniform illuminance along a first longitudinal axis (X), with respect to the development of said rows of lenses (11), of said superficial portion (20, 30) made of diffusing material, thus becoming a surface of secondary emission.

7. A LED (12) lighting appliance (15) as claimed in claim 5, characterized in that said superficial portion (20, 30) made of diffusing material has a uniform illuminance or decreases from the center to the edges of the lighting appliance (15) along a second axis (Y) which is perpendicular with respect to said first longitudinal axis (X).

8. A LED (12) lighting appliance (15) as claimed in claim 4, characterized in that said central zone (111) and said external lateral zone (112) of each lens (11) have segmented surfaces (13, 14) like a Fresnel lens, with respect to an origin of the light rays viewable in an optical center (110).

9. A LED (12) lighting appliance (15) as claimed in at least one of the preceding claims, characterized in that one or more surfaces of said refractive element (10), which are not designed specifically for an optical function, have a satin finish.