CA2535336A1 - Luminaire having bipartite optical system consisting of a reflector complemented by a deflector to achieve high uniformity and low glare - Google Patents

Abstract

An luminaire having a bipartite optical comprises an upper reflector including reflecting facets, and an opening in the reflector for emitting light from a light source to an area to be illuminated. A primary light source is mounted within the reflector, the primary light source having a diameter and a longitudinal axis which is substantially parallel to the upper reflector. An image of the light source is displayed by each of the facets in a predetermined direction, each the image being parallel and adjacent to edge for each of the facets. An illumination uniforming deflector is disposed below the primary light source to redirect light incident on it to the upper reflector for maximum utilization.

Description

FIEILD OF THE INVENTION

[0001] This invention relates generally to luminaires and more particularly to a luminaire with a bipartite optical system having an illumination uniforming and glare reducing deflector design.
BRIEF DESCRIPTION OF THE DRAWINGS

[0002] The novel features which are believed to be characteristic of the luminaire according to the present invention, as to its structure, organization, use and method of operation, together with further objectives and advantages thereof, will be better understood from the following drawings in which a presently preferred embodiment of the invention will now be illustrated by way of example. It is expressly understood, however, that the drawings are for the purpose of illustration and description only, and are not intended as a definition of the limits of the invention. In the accompanying drawings:

[0003] Figure 1 shows a typical prior art luminaire having a reflector made from segments of highly reflective material showing image of the upper part of the light source, with the bottom part of the light source being visible and causing glare, and contributing all light downwards and directly below the luminaire;

[0004] Figure 2 shows a typical prior art luminaire having a reflector made from one piece hydro-formed shape usually from aluminum sheet finished in specular or semispecular finish showing light source image from one side only;

[0005] Figure 3 is a cut-away end view of a prior art luminaire, showing direct light emitted by the bottom side of the primary light source not captured by this prior art reflector, and also showing the bottom side of the bright light source to be visible from directly below the luminaire, with the reflected light from the upper part of the arc to not shown for the sake of clarity;

[0006] Figure 4 is a cut-away end view of the preferred embodiment luminaire having a bipartite optical system, according to the present invention, showing light captured by the deflector and directed to the upper reflector, and then redirected to the required field, thus reducing light in the field directly below the luminaire and increasing light in the perimeter field;

[0007] Figure 5 is a cut-away end view of the preferred embodiment luminaire of Figure 4, showing that the view of the primary light source is blocked;

[0008] Figure 6 is a perspective view from one end of the preferred embodiment luminaire of Figure 3, showing how the deflector blocks direct light from the light source, and with the upper part acting as a reflector to distribute light downwards based on images of the upper parts of the arc tube of the light source as well as the reflected light from the bottom parts of the arc tube collected from the lower deflector, thus reducing the light coming down directly from the bottom parts of the arc tube;
and, [0009] Figure 7 is a perspective view from the other end of the preferred embodiment luminaire.

BACKGROUND OF THE INVENTION

[00010] Luminaires, for the illumination of large areas, and the things situated thereon, have been available for many years.
Luminaires having specular reflecting facets have been available for about thirty years. Luminaires with hydro formed shaped one piece construction reflectors have been available for over fifty years. Such luminaires are used in interior and exterior areas, pedestrian and vehicular traffic areas, parking areas, malls, plazas, sports fields, etc. Depending on the application, the light emitting side of this type of luminaire may be horizontal, tilted or vertical and may face downward or upward. Luminaires for these applications go by different names such as: floodlight, street light, roadway luminaire, walkway bollards, and area luminaire.

[00011] A luminaire with multiple facets produces relatively high beam strength toward the perimeter of predetermined area zone that the luminaire is designed to light. In this way the illumination is falling on a much larger area lighted by a system of such luminaires, thus allowing wider spacing between luminaires. However wider spacing results into poorer uniformity of illumination across this area. This poor uniformity makes it difficult to meet desired uniformity ratio mandated by various jurisdictions. The high brightness of the primary light source also results in excessive glare in the directions of view from below the luminaire.

[00012] Bipartite optical systems, which consist of the illumination uniforming and glare reducing deflector device overcome the above discussed limitations of prior art reflectors by rearranging light distribution characteristics that sharply reduce the light immediately below the luminaire and reducing glare by blocking the view of the brightest part of the luminaire, which is the primary light source.

[00013] An energy efficient electric lamp with a long life rating and energy efficiency in common use today in such luminaires consists of a high intensity electric arc discharge tube enclosed in a protective clear or translucent glass bulb. Typically, the arc tube is also transparent, and accordingly the electric arc within the tube may be seen (through a welding a mask lens) to have finite length and thickness. The arc itself is the primary light source. These electric lamps available today include high pressure sodium, metal halide, compact fluorescent, and induction lamp technologies.

[00014] Prior art reflectors would reflected light in opposite direction from each facet of reflector depending on the incident angle of the light from the primary light source. Generally the reflector is placed above the light source collecting light above the horizontal plane. The light from the primary source below horizontal plane is not captured by the reflector but gets emitted downwards directly towards the area to be illuminated. This results into large pool of light below the luminaire causing poor uniformity. The lack of deflector below the primary light source enables brightest parts of the light source viz-arc tube to be visible from various viewing angles.

[00015] United States Patent 5,690,422 issued November 25, 1997 to Brass, discloses a luminaire comprising a high intensity arc discharged lamp as its primary light source, and a reflector over the high intensity arc discharge lamp. The reflector includes a plurality of specular reflecting facets with fine-lined geometry.
Each of the fine-lined facets displays a primary light source image that is parallel and adjacent to the cutoff edge of that facet.
However, the illumination immediately below the luminaire is considerably higher than the surrounding illumination, thus resolving in non-uniform illumination, therefore making it difficult to meet uniformity standards.

OBJECTS AND ADVANTAGES

[00016] The objects and advantages of the invention, as compared to prior art luminaires (using the same light source) are:

(a) to allow a luminaire to cover significant increase in the size of the area zone illuminated (due to wider beam angles), with greater uniformity;

(b) for luminaire to provide significantly increased illumination levels around the perimeter of the area zone;

(c) to significantly increase utilization of the light of the primary light source output by deflecting downward coming light to the upper reflector which redirects to the area zone;

(d) to significantly reduce the amount of the primary light source output directly below the luminaire;

(e) to significantly reduce the glare from below the luminaire by providing arc tube view cutoff;

(f) better peripheral light distribution and reduction in light directly below the fixture allow designers to meet minimum uniformity criteria with wider spacings than prior art luminaires (conversely the prior art luminaires would have to be larger in light source size, more expensive and larger energy consumer to allow the design of lighting systems than utilizing this invention that can satisfy or exceed a given minimum illumination requirement);

(g) to realize significant reductions in initial costs and maintenance costs for lighting systems; and (h) to realize significant energy cost reductions.
SUbIlMARY OF THE INVENTION

[00017] In accordance with one aspect of the present invention there is disclosed a novel luminaire having a bipartite optical system. The luminaire comprises an upper reflector including reflecting facets, and a primary light source is mounted within the reflector, the primary light source having a diameter and a longitudinal axis which is substantially parallel to the upper reflector. There is an opening in the reflector for emitting light from a light source to an area to be illuminated. An image of the light source is displayed by each of the facets in a predetermined direction, with each of the images being parallel and adjacent to the edge for each of the facets. An illumination uniforming deflector is situated below the primary light source to redirect light incident on it to the upper reflector for maximum utilization.

[00018] This invention involves the discovery of a bipartite optical device consisting of two components namely, an illumination uniforming deflector device, below a primary light source complementing the main reflector above the primary light source to improve uniformity and reduce glare. The directions of the two components can be variable.

[00019] The key invention described herein of illumination uniforming and glare reducing deflector device overcomes some of above limitations. By placing a complimentary reflector directly below the arc tube of the primary light source, the light emitted downwards is captured and reflected back to the upper reflector in multiple directions. The high reflectivity of over 90% and multiple images formed in this complimentary deflector redirects this downward light from the primary source, thus increasing the overall efficiency in the wider angles while reducing the illumination directly below the luminaire. It further acts as a cutoff device to reduce view of the bright arc tube of the primary source from viewing angles from below to minimize glare.

[00020] An important characteristic of the invention is that the images of the primary light source displayed by the main reflector, at a given main beam angle captures light from deflector device below the primary light source. Prior art designs display partial images of the light source, without capturing the image from below the light source. This characteristic of prior art luminaires limits their main beam intensities, resulting in poor uniformity.

In the prior art designs, the brightness of the primary source caused glare as its view was not sufficiently cut off.

[00021] An optical principle for use in the design of lighting reflectors with an illumination uniforming deflector device is disclosed, and a luminaire embodying this optical principle is described. The luminaire described comprises a high intensity arc discharge lamp, as a primary light source with finite length and thickness, and a current art reflector consisting of facets reflector including a multiple of specular reflecting surfaces with a multiple geometry or a hydro formed shaped reflector. Each of these facets displays a primary light source image in desired direction. However the illumination resulting immediately below the luminaires is considerably higher than illumination away from the luminaire. This results into non uniform illumination making it difficult to meet uniformity standards. In the current art reflector, the primary light source is directly visible from below the luminaire causing excessive glare from the brightness of the primary light source. The name of this invention relates to a current art reflector and a supplementary deflector device below the primary light source which will block direct light going to the area directly below the luminaire. It will also redirect this light to the upper reflector system to the side and above the light source. This enables the maximum utilization of light from the primary source without compromising uniformity as this device reduces direct light going to the field below. It further reduces the glare from the primary light source by blocking the view of this source from below the luminaire.

[00022] Other advantages, features and characteristics of the present invention, as well as methods of operation and functions of the related elements of the structure, and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following detailed description and the appended claims with reference to the accompanying drawings, the latter of which is briefly described herein below.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[00023] Referring to Figures 1 through 7, it will be noted that Figure 1 illustrates a first prior art luminaire, Figure 2 illustrates a second prior art luminaire, Figure 3 illustrates a third prior art luminaire and Figures 4 through 7 illustrate the preferred embodiment of the luminaire of the present invention.
Due to complexity of this multidirectional device, photographs are provided to complement line drawings for greater clarity.

[00024] Reference will now be made to Figures 4 through 7, which show a preferred embodiment of the luminaire of the present invention, as indicated by general reference numeral 20. The luminaire 20 comprises an upper reflector 30 including reflecting facets 32 that may be specular, or semi-specular. The reflecting facets 32 are also disposed in a multi-tiered group, and are substantially contiguous and are of various length.

[00025] A primary light source 40, such as a high intensity arc discharge lamp, is mounted within the upper reflector 30. The primary light source 40 has a diameter and a longitudinal axis "L"
that is substantially parallel to the upper reflector 30. An image of the light source 40 is displayed by each of the reflecting facets 32 in a predetermined direction. Each image is parallel and adjacent to the edge at of the reflecting facets 32.

[00026] An illumination uniforming deflector 50 is mounted on the upper reflector 30 so as to be disposed immediately below the primary light source 40, to thereby redirect light incident on it to the upper reflector 30, for maximum utilization of the light.
The illumination uniforming deflector 50 also blocks the view of the primary light source 40, as can be best seen in Figure 5, thereby reducing glare. Preferably, the illumination uniforming deflector 50 is made from a reflecting material and is mounted parallel to the primary light source 40.

[00027] There is an opening 34 in the upper reflector 30, typically in the bottom of the reflector, for emitting light from the primary light source 40, to an area to be illuminated.

[00028] As can be seen in the Figures, the tiered facet group and the illumination uniforming deflector 50 are attached in one piece.
Further, the multiple-tiered facet groups are arranged substantially side by side, with the illumination uniforming deflector 50 disposed below the primary light source 40, with the multi-tiered facet groups having adjacent side edges that are substantially contiguous and of various lengths, thereby causing the deflector to redirect light to the facets resulting in more uniformed lighting over a larger area, as indicated by arrows "A"
in Figure 4. Further, the direct view of the primary light source 40 is blocked, as indicated by arrows "B" in Figure 5.

[00029] As can be understood from the above description and from the accompanying drawings, the present invention provides luminaire that covers a significantly increased size in the area zone illuminated due to wider beam angles, with greater uniformity, that provides significantly increased illumination levels around the perimeter of the area zone, that significantly increases utilization of the light of the primary light source output by deflecting downward coming light to the upper reflector which redirects to the area zone, that significantly reduces the amount of the primary light source output directly below the luminaire, that significantly reduces the glare from below the luminaire by providing arc tube view cutoff, that provides better peripheral light distribution and reduction in light directly below the fixture to allow designers to meet minimum uniformity criteria with wider spacings than prior art luminaires, that realizes significant reductions in initial costs and maintenance costs for lighting systems, and that realizes significant energy cost reductions, all of which features together are not achievable by the prior art.

[00030] Other variations of the above principles will be apparent to those who are knowledgeable in the field of the invention, and such variations are considered to be within the scope of the present invention. Further, other modifications and alterations may be used in the design and manufacture of the luminaire 20 of the present invention without departing from the spirit and scope of the accompanying claims.

Claims (12)

1. A luminaire having a bipartite optical system, said luminaire comprising:

an upper reflector including reflecting facets;

a primary light source mounted within said reflector, said primary light source having a diameter and a longitudinal axis that is substantially parallel to the upper reflector;

an opening in said reflector for emitting light from primary light source to an area to be illuminated;

wherein an image of said light source is displayed by each of said reflecting facets in a predetermined direction, each said image being parallel and adjacent to edge for each of said facets; and, an illumination uniforming deflector below the primary light source to redirect light incident on it to said upper reflector for maximum utilization.

2. The luminaire of claim 1, wherein said illumination uniforming deflector is made from a reflecting material.

3. The luminaire of claim 2, wherein said illumination uniforming deflector is mounted parallel to the primary light source.

4. The luminaire of claim 1, wherein said reflecting facets are specular.

5. The luminaire of claim 1, wherein said reflecting facets are semi-specular.

6. The luminaire of claim 1, wherein said facets are disposed in a multiple tiered group.

7. The luminaire of claim 1, wherein said facets are substantially contiguous.

8. The luminaire of claim 1, wherein said facets are of various lengths.

9. The luminaire of claim 1, wherein said tiered facet group and illumination uniforming deflector are attached in one piece.

10. The luminaire of claim 6, wherein said multiple tiered facet groups are arranged substantially side by side, with said illumination uniforming deflector disposed below the primary light source.

11. The luminaire of claim 6, wherein said multiple tiered facet groups have adjacent side edges that are substantially contiguous and various lengths, thereby causing said deflector to redirect light to these facets resulting in more uniform lighting over a larger area.

12. The luminaire of claim 1, wherein said illumination uniforming deflector below the primary light source blocks the view of said illumination uniforming deflector, thereby reducing glare.