Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V7/00—Reflectors for light sources
  • F21V7/04—Optical design
  • F21V7/08—Optical design with elliptical curvature
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V13/00—Producing particular characteristics or distribution of the light emitted by means of a combination of elements specified in two or more of main groups F21V1/00 - F21V11/00
  • F21V13/02—Combinations of only two kinds of elements
  • F21V13/10—Combinations of only two kinds of elements the elements being reflectors and screens
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B19/00—Condensers, e.g. light collectors or similar non-imaging optics
  • G02B19/0004—Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed
  • G02B19/0019—Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed having reflective surfaces only (e.g. louvre systems, systems with multiple planar reflectors)
  • G02B19/0023—Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed having reflective surfaces only (e.g. louvre systems, systems with multiple planar reflectors) at least one surface having optical power
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B19/00—Condensers, e.g. light collectors or similar non-imaging optics
  • G02B19/0033—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use
  • G02B19/0047—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use for use with a light source
  • G02B19/0061—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use for use with a light source the light source comprising a LED
  • G02B19/0066—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use for use with a light source the light source comprising a LED in the form of an LED array
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V7/00—Reflectors for light sources
  • F21V7/0008—Reflectors for light sources providing for indirect lighting
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
  • F21Y2103/00—Elongate light sources, e.g. fluorescent tubes
  • F21Y2103/10—Elongate light sources, e.g. fluorescent tubes comprising a linear array of point-like light-generating elements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
  • F21Y2115/00—Light-generating elements of semiconductor light sources
  • F21Y2115/10—Light-emitting diodes [LED]

Definitions

• the present invention fits in the field of the illuminating engineering, and in particular relates to an optical system for uniform distribution of light emitted by punctiform light sources, particularly Light- Emitting Diodes (LEDs).
• LEDs Light- Emitting Diodes
• the invention concerns an apparatus for indoor lighting, which takes advantage of the use of punctiform light sources, such as LEDs, and ensures a homogeneous light distribution, while keeping a high efficiency of the apparatus.
• LEDs have demonstrated a high application potential in the field of architecture, having numberless advantages.
• EN 12464-1 analyzes the usual visual tasks, highlighting the needs of visual comfort and giving indications about the lighting levels, uniformity and maximum dazzling degree necessary for the various visual performances that involve the use of display terminals.
• mirror-like reflectors are used, which partly deflect the radiation of the LED.
• These devices have the drawback of however presenting an excessive luminance, since the radiation seems to come from the LED itself for the direct light, or from the virtual LED source (mirror-like reflector) for the reflected light.
• Another solution, used in some devices shown in figure 1c, is to take sets of LED, shielded from diffusing filters.
• Purpose of the present invention is therefore to overcome the drawbacks of the prior art, creating an optical system for uniform distribution of light emitted by punctiform light sources.
• primary purpose of the present invention is to design an optical system for limiting dazzling caused by direct or indirect light of LEDs, without for this reason losing the efficiency of the lighting body obtained.
• Further purpose of the invention is to provide an optical system for uniform distribution of light emitted by punctiform light sources, in which the radiations coming from these sources undergo only one reflection, in order to avoid the efficiency losses that usually occur with the multiple reflections.
• Purpose of the invention is to provide an optical system for uniform distribution of light emitted by punctiform light sources, in which these sources are not visible either directly or indirectly, reflected on a reflector.
• Yet another purpose of the present invention is to indicate an optical system for uniform distribution of light emitted by punctiform light sources, which ensures sufficiently high and rationally distributed luminance, in connection with the lighting deriving from ambient or external light, in order to allow the perception of the important areas, as well as of the details, and minimize any form of dazzling.
• purpose of the present invention is to carry out an efficient optical system of simple and economic construction, so as it can be put into the market at a competitive price, offering an advantageous energy saving.
• the present invention fits in, aimed at achieving elegance, efficiency and reliability features in an optical system for uniform distribution of light emitted by punctiform light sources, whose structure, in this way, presents aesthetic and functional advantages.
• FIG. 1a shows schematically a first optical system for the diffusion of the light emitted by a punctiform light source according to a first known solution
• FIG. 1b shows schematically a second optical system for the diffusion of the light emitted by a punctiform light source according to a second known solution
• FIG. 1c shows schematically a third optical system for the diffusion of the light emitted by a punctiform light source according to a third known solution
• FIG. 1d shows schematically a fourth optical system for the diffusion of the light emitted by a punctiform light source according to a fourth known solution
• FIG. 2 is a perspective view from the bottom of an optical system according to the invention.
• FIG. 3 is an assonometric cross-section of the optical system of figure 2, in which the screening element is not present;
• figure 4 is a sectional view of half of the primary optical system of figure 3, in which the schematic rays tracing is shown, in the ideal case of punctiform light source and totally mirror-like reflector;
• figure 5 shows the rays tracing in the optical system of figure 2 with diffusing primary optics and screening element.
• optical system, object of the invention which can be partly or fully used, in one or more units, in the design of a reflector for lighting apparatuses, is defined as follows.
• the optical system consists of a primary optics 2 and a screening element 3.
• the primary optics 2 is formed by one or more sets of LEDs 4 and one or more diffusing reflective surfaces 5.
• the screening element 3 consists of an anti-dazzling grid with one or more reeds 6.
• the particularity of the primary optics 2 consists in that the radiation 7, coming out of it, is not the direct radiation 8 of the LEDs 4.
• the LEDs 4 are not directly visible and their radiation 8 is conveyed outside the apparatus is conveyed by the diffusing reflective surfaces 5.
• the direct radiations 8 of the LEDs 4 are thus distributed on an area larger than those ones of emission, namely those one of the LED 4 themselves.
• the luminance resulting from such a primary optics 2, then, is lower than that one which would arise in case of direct light emission by the same group of LEDs 4.
• the primary optics 2 is designed so that the radiations 8 coming from the LEDs undergo a single reflection, thus avoiding efficiency loss which would arise with multiple reflections.
• highly reflective materials are used to produce the diffusing reflective surfaces 5.
• the material used is satiny aluminium with high reflectance; alternatively, plastic or metallic materials, painted with a diffusing white paint with high reflectance, can be used, obtaining in this second case a better comfort, although at the expense of efficiency.
• the primary optics 2 consists of two parts 9 symmetrical with respect to a central plane 10.
• the reflector is obtained by extruding an elliptical profile in each part 9.
• the LEDs 4 are arranged along a row 11 coincident with the axis perpendicular to the plane of the ellipse, passing through one of the focus F1 of the ellipse itself.
• the tracing of rays 7, 8 is shown in section, in the simplified case of only one punctiform light source with bidimensional emission on the drawing plane and in case of a mirror-like reflector.
• the radiation 7 is directed from the reflective surface 5 towards the outside of the primary optics 2, after giving undergone a single reflection on it.
• the second focus F2 of the ellipse where most of the rays 7 concentrate, coming from the ideal punctiform source 12, after having been reflected by the reflecting surface 5, can be placed in a different position compared to that one illustrated, provided that the abovementioned requirements are met, of minimizing the number of interactions with the reflective surfaces 5.
• the inner surface of primary optics 2 is obtained by using a diffusing instead of mirror-like material. This also allows to increase the emitting surface thereby reducing the dazzling coming from the apparatus.
• the LEDs 4 are oriented so as to maximize the flow coming out from the apparatus.
• the screening element 3 is a CPC (Compound Parabolic Concentrator) anti- dazzling grid, which reduces the angle of emission of the radiation by the primary optics 2.
• CPC Compound Parabolic Concentrator
• the reeds 6 of the grid are designed with an angle having a cut-off value of 60 degrees. With angles greater than 65° with respect to the vertical direction, a luminance lower than 200 cd/m 2 is reached.
• the use of a CPC grid for the screening element must not be intended as restrictive.
• the screening element could also consist for instance of reeds obtained from extruded circumference arcs or planes.
• the primary optics 2 and the screening element 3 form together a single complete optical system 1 (or cell) that can be repeated depending on the overall output flow required for the lighting apparatus to which it is desired to applied it.
• two cells 1 symmetric with respect to a plan, constitute a basic form.
• an elementary module may consist of a single cell 1 or any number of cells 1 arranged according to various symmetry criteria, or even one of the two parts 9 of the primary optics 2, with an appropriate screening element, if necessary.
• optical unit according to the invention by applying the optical unit according to the invention to a lighting body, it is possible to light very wide areas, still ensuring a substantially uniform lighting on the work top.
• Another advantage of the current invention is to provide a smaller number of light sources in order to get the lighting level required by the regulations, thanks to the high efficiency of LED light sources and thanks to the high efficiency of the optical system described.

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Cited By (3)

Citations (6)

• 2010
  • 2010-07-30 IT ITVI2010A000214A patent/IT1402274B1/it active
• 2011
  • 2011-06-17 WO PCT/IT2011/000208 patent/WO2012014239A1/en active Application Filing

Patent Citations (6)

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