US3716709A - Zero luminance lighting panel - Google Patents

Zero luminance lighting panel Download PDF

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Publication number
US3716709A
US3716709A US00152726A US3716709DA US3716709A US 3716709 A US3716709 A US 3716709A US 00152726 A US00152726 A US 00152726A US 3716709D A US3716709D A US 3716709DA US 3716709 A US3716709 A US 3716709A
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pyramid
arcs
symmetry
circumference
axis
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US00152726A
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English (en)
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I Taltavull
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Individual
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    • 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
    • F21V5/00—Refractors for light sources
    • F21V5/002—Refractors for light sources using microoptical elements for redirecting or diffusing light
    • F21V5/005—Refractors for light sources using microoptical elements for redirecting or diffusing light using microprisms
    • 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
    • F21V5/00—Refractors for light sources
    • F21V5/04—Refractors for light sources of lens shape
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
    • G02B5/021—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures
    • G02B5/0215—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures the surface having a regular structure
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G02B5/0273—Diffusing elements; Afocal elements characterized by the use
    • G02B5/0278—Diffusing elements; Afocal elements characterized by the use used in transmission

Definitions

  • Two conditions which a lighting panel must fulfil are that it must have a high lighting efficiency permitting the passage of the greatest possible number of light rays and that it must have the lowest possible luminance insofar as of the number of rays passing through the panel possible number do so forming with the vertical, at angles between 60 and 90 so as to avoid a glare effect.
  • opal type panels in general give a low lighting output ratio and excessive glare; prismatic type panels, fitted with transparents prisms or pyramids have a good lighting output ratio but suffer from the fact that they also have a very high luminance; and lastly, louver type panels, while having no, or very little luminance, have a very low lighting efficiency.
  • Another object of the invention is to provide a highly efficient optical lighting panel, that has a high output ratio in comparison with other lighting panels.
  • Another object of the invention is to provide a transparent prismatic lighting panel of substantially zero luminance.
  • a transparent plastic lighting panel provided with a plurality of refracting prismatic protrusions on its exterior surface.
  • These protrusions are in the form of pyramids or cones and the lateral surfaces of these cones and pyramids are of such curvature that substantially none of the light rays are refracted through these pyramids and cones at angles between 60 and 90 with respect to the cone or pyramid axis. This results in a substantially zero luminance lighting panel.
  • FIG. 1 is a schematic illustration of a prism of a prior art lighting panel showing the trajectory of an eccentrical beam of light.
  • FIG. 2 is a schematic representation of the profile of a curvilinear pyramid of a panel of the present invention taken along the line 10-10 of FIG. 4, showing the angles which determine said profile.
  • FIG. 3 is a schematic illustration of the profile of the same curvilinear pyramid of FIG. 2, considered along the line 17- 17' of FIG. 4, showing the corresponding angles.
  • FIG. 4 is a fragmentary top plan view of a lighting panel of the invention with hexagonal curvilinear pyramids.
  • FIG. 5 is a fragmentary top plan view similar to that shown in FIG. 4, but showing a modification of the in vention in which the panel is provided with curvilinear cones.
  • FIG. 6 is a diagrammatical view of the profiles of a cone of the panel along lines 32--32' and 35-35 of FIG. 5.
  • FIG. 7 is a schematic illustration of the profile of a curvilinear cone of the panel along line 32-32 of FIG. 5, showing the trajectory of an eccentrical beam of light.
  • FIG. 8 is a schematic illustration of the profile of a curvilinear pyramid of the panel along line l0-l0' of FIG. 4, showing the trajectory of an eccentrical beam of light.
  • the invention comprises a prismatic lighting panel suitable for use in recessed, flush, pendant, or other known lighting fixtures.
  • These panels are provided with prismatic elements designed with a particular curvature which produces a distribution of light (depending on the angle in the vertex of these prismatic elements) such; that a very low luminance (approaching zero) is achieved.
  • FIG. 1 it can be seen that with prior art prisms having flat lateral surfaces three types of rays issue from the panel.
  • the second rays issue at angles of between 60 and and therefore produce glare, and the third rays issue through the upper part of the panel resulting in loss.
  • the panel which closes the fitting and contains the prismatic elements receives rays of light from all directions and on all of the flat surface exposed to the fluorescent tubes.
  • the straight lines CD and CD cut the line ST, which represents the upper plane 24 of the panel, at the points D and D situated between the points ll, 12 and 11, 12'.
  • the radiations which issue from D and D' or any point between these points do not undergo any internal reflection as they have an angle of incidence in the face of the pyramid less than the critical angle and are thus refracted.
  • the radiations issuing from the surface of the panel furthest from the axis of the prism produce rays of light which strike the faces of the pyramid at incidence angles greater than that of the critical angle. This means that they suffer total internal reflection instead of being refracted.
  • there is no internal reflection of the radiations which issue from points between D and D total internal reflection taking place at 16 and 16'.
  • Radiation issuing from point 15' has been selected because said radiation illustrates clearly the behavior of rays 2a, 2b, 2c, 2e, 2f, 23, which are usefully refracted with issuing angles of less than 60, of the rays 4g, 4i, which produce glaring issuing with angles of between 60 and 90, of the ray 4j which on entering the immediate prism and others not represented in the drawing, is refracted and reflected on incidence with these prisms, finally to pass through one of these issuing with an angle of 60, that is, on the border between the rays which produce glare and those which don't; and finally of the rays 3e and 3h which suffer total. internal reflection and pass through the upper part of the panel with the consequent loss oflighting.
  • A marks the zone which produces glaring rays and B marks the zone which produces rays that are lost. The remaining refracted rays are useful. It should be noted that the ray 2-3e which corresponds to the critical angle is subdivided into the rays 2e and 3e, that is, it corresponds to the border of the zone 3,.
  • the invention consists of a prismatic type transparent plastic panel in which refracting prismatic elements have the form of pyramids with square or hexagonal bases.
  • the lateral faces of the elements have curved or more exactly cylindrical surfaces. These are curved in such a way that the profiles of the sections of these pyramids determined by axial planes normal to the lateral faces of the pyramids, are determined by two equal arcs of circumference which meet at in the vertex of the pyramid.
  • angles a and ,8 constitute the basic elements from which the following formulas obtain the values of 8 and 7 which fix the position of the centers of the arcs and their corresponding curvatures.
  • FIG. 3 represents the geometric construction of a section of the same curvilinear pyramid but taken from line l7l7' of FIG. 4.
  • the straight line 8 of FIG. 3 represents the upper part of the panel.
  • FIG. 4 also shows that the distances UP; and UG', are directly related because UF' UG X cos 30 given that the figure is a hexagon. Therefore the arcs 9 and 9' of FIG. 3 are portions of two ellipses with equal semi-axis.
  • the lesser semi-axis E V has the same dimensions as the radii E F' and E F, of the lesser arcs of circumference of FIG. 3. These are also equal to the arcs of circumference of FIG. 2.
  • the greater semi-axis E8, of the ellipse is the result of the distances M F', and M F of FIG. 2 having become the distances M 6 and M G of FIG. 3 according to the relationships:
  • M G M F lCos 30 and These data are sufficient, by means of a well known geometrical construction, to draw the segments of the ellipses, that is, from point G" the triangle F GH is drawn and point H is found which in turn fixes the radius E H which corresponds to the dimension of the greater semi-axis of the ellipse.
  • the triangle KJI is repeated as often as necessary for the construction of the segments of the ellipse.
  • the prismatic refracting elements of the panel take the form having cones of circular bases and in which the generatrix is a non-straight line.
  • the generatrix in general is a curved line of such curvature that the profiles of the sections of these cones determined by planes parallel to the axes of the cones and normal to the bases are determined by two arcs of circumference which are similar to those described in reference to FIG. 2 in the case of prismatic refracting elements in the form of curvilinear pyramids.
  • FIG. 5 represents said variation of the panel which is of zero luminance and in which the prisms are formed by cones instead of pyramids, the generatrix being the profile G 'C of FIG. 6.
  • Such a panel possesses other smaller cones which serve to fill the spaces between the principal cones, as shown in FIG. 5, in such a way that there is practically no space without prisms.
  • the shape of these smaller cones is similar to that of the main cones, the diameter at the base of said smaller cones being 0.155 of the diameter of the main cones.
  • FIG. 6 is a geometric representation of the generation of the curvilinear cone which is a solid of revolution, the axial section showing the curve 0' 6' G';,, G G and C, as the generatrix.
  • the lower half of FIG. 6 below the straight line WW corresponds to the view of the horizontal sections through G' G G G G' G G' G and G' C, while the upper half above the straight line W'WS corresponds to the view through vertical sections by 0,0 and WW of the figure.
  • curve F' C of FIG. 2 represents the axial section of the curvilinear pyramid, having a zero luminance value.
  • the curve F' C of FIG. 2 corresponds to a section of the cone at half the distance of the value r of the radius of the base of the cone.
  • the curve G',C is the generatrix curve of the curvilinear cone in its axial section.
  • the curve then has a straight part 6' 6' 0' tangent to the first part and ends with an arc of circumference G' C with its center at G
  • the curvilinear cone of the instant invention has a zero luminance. This is proved by the graphical calculations corresponding to sections in any axial or nonaxial direction of FIG. 5.
  • the curvilinear pyramid if cuts are made in FIG. 4 in sections parallel to 17-17, such as XX, there is some small amount of luminance in the flat parts marked 34, in FIG. 3.
  • FIG. 7 represents a sectional view of a curvilinear cone having a profile drawn according to the lines G' C of FIG. 6 and corresponding to a cut in the panel according to the line 32--32' of FIG. 5. Radiations corresponding to point 21 and the normals to the surface at the points of incidence of the rays are all shown. It can be seen that the rays 6d, 6e, 6f, and 6j, fall within the zone B of lost rays.
  • the useful rays 5a, Sb, 5c, 5d, 5i, and 5g are refracted with issuing angles lower than 60. There is no zone A in this embodiment as there are no glare rays refracted falling between 60 and 90.
  • this section of the curvilinear cone has zero luminance; The same thing happens at any point of ray emission from the surface of the panel. Except for zone B there are only useful zones of radiation at the points situated between the axis of the prism and the limit points 23 and 23. The same can be shown to be true when the section of the curvilinear cone is made through non-axial planes represented in FIG. 5 by the straight lines 34-34 and 35-35.
  • FIG. 8 corresponds to the section according to the cut l0 10 of FIG. 4 of a curvilinear pyramid and the point of situation of the radiation is marked 29.
  • the beams 6 ⁇ , 6g and 6H are within zone B of lost beams, while 5a, 5b, 5c, 5d, 5e, 5f, 5h, 5i, and Sj, are useful beams with an issuing angle of less than 60.
  • a similar situation is produced in the beams situated between the axis of the prism and the limit points 3H and 31'.
  • the efficiency of the prismatic panels is far higher than that of opal or louver panels.
  • the louver panels have a very low luminance, a quality not possessed by opal panels nor normal prismatic panels.
  • the output ratio of all lighting fixtures with fluorescent light sources depends to a high degree on the efflciency of the baked enamel reflector which forms the upper part of the fixture.
  • the output ratio of fixtures using louver panels in the case of recessed fixtures, where there is a greater proportion of strayed rays, is below 30 percent; in fixtures using opal panels it is about 50 percent and in fixtures with prismatic panels, it is about 60 percent. The losses of the normal prismatic panel and the zero luminance prismatic panel will now be compared.
  • a transparent prismatic lighting panel comprising in its outer surface a plurality of pointed optical prismatic refracting elements having respective axes of symmetry which pass through their vertices, the axial sections of said prismatic elements taken in planes normal to their lateral surfaces being limited by symmetrical curved lines with respect to the said axis of symmetry, the convexity of said curved lines being towards the outside of the panel, said optical prismatic refracting elements consist of pyramids the lateral faces of which are equal cylindrical surfaces and the curvature of the generatrix of said cylindrical surfaces is such that the sections of each pyramid taken according to axial planes normal to two opposite faces of the said lateral faces are limited by two arcs of circumference symmetrical with respect to said axis of symmetry of the pyramid, the center of said arcs of circumference being situated above the base of the pyramid and symmetrically on opposite sides of said axis of symmetry of the pyramid.
  • a transparent prismatic lighting panel which has on its exterior surface a plurality of optical refracting pyramids, each one of which has an axis of symmetry which passes through its vertex and the lateral faces of where:
  • a is the angle in the vertex of the section of the pyramid between the chords of the arcs of circumference
  • B is the angle formed with the base of the pyramid by a straight line normal to a tangent of one of said arcs of circumference at the point at which the arc cuts the base of the pyramid;
  • y is the angle covered by each of the said arcs of circumference
  • a transparent lighting panel comprising in its outer surface a plurality of pointed optical prismatic refracting elements having respective axes of symmetry which pass through their vertices, the axial sections of said prismatic elements taken in planes normal to their lateral surfaces being limited by symmetrical curved lines with respect to the said axis of symmetry, the convexity of said curved lines being towards the outside of the panel, said optical prismatic refracting elements consisting of cones having circular bases, the generatrix of said cones being a curved line of such curvature that the sections of each of said optical cones taken through planes parallel to said axis of symmetry and normal to the base of said cone at the median point of radius are limited by arcs of circumferences symmetrical with respect to a straight line normal to said base at the median point of said radius, the centers of said arcs of circumference being situated above the base of said cone and symmetrically on opposite sides of said straight line.
  • a transparent prismatic light panel according to claim 6 comprising, in its outer surface, a plurality of optical cones similar to, but smaller than, said conical refracting cones, substantially filling the spaces between the bases of said larger optical refracting cones.
  • a transparent prismatic lighting panel comprising, in its outer surface, a plurality of circular based optical refracting cones, each cone having an axis of symmetry which passes through its vertex, the generatrix of said cone being a curved line and sections of each one of said 0 tical cones taken through planes parallel to said axis 0 symmetry and normal to the base of said cone at the median point of a radius are limited by two arcs of circumference symmetrical with respect to a straight line normal to said base at the median point of said radius, the centers of said arcs of circumference being situated above the base of said cone and symmetrically situated on opposite sides of said straight line at points determined by the following formulae:
  • a is the angle in the vertex of the section of the pyramid between the chords of the arcs of circumference
  • B is the angle formed with the base of the pyramid by a straight line normal to a tangent of one of said arcs of circumference at the point at which the arc cuts the base of the pyramid;
  • a transparent prismatic lighting panel in which the profiles of the axial sections of each of the said cones are limited by two lines symmetrical with respect to the axis of symmetry of the cone, each of which comprises a first arc of circumference, the center of which is situated at the other side of said axis of symmetry and above the plane of the base of the cone; a segment of straight line tangental to the first arc of circumference, and a second arc of circumference the center of which is situated at the other side of the axis of symmetry and on the plane of the base of said cone.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Optical Elements Other Than Lenses (AREA)
US00152726A 1971-06-14 1971-06-14 Zero luminance lighting panel Expired - Lifetime US3716709A (en)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4451872A (en) * 1980-11-26 1984-05-29 Kernforschungsanlage Julich Gesellschaft Mit Beschrankter Haftung Process for the most uniform illumination of a surface by a collimated beam of rays and arrangement for laser diagnostic
US4703405A (en) * 1986-07-17 1987-10-27 Ian Lewin Glare reducing lens
US20020114149A1 (en) * 2000-12-13 2002-08-22 Mitsubishi Rayon Co., Ltd. Light source device
US20060203490A1 (en) * 2005-03-10 2006-09-14 Honeywell International Inc. Luminaire with a one-sided diffuser
EP2195574B1 (en) * 2007-10-02 2017-06-28 iGUZZINI ILLUMINAZIONE S.p.A. Optical screen for directing light beams with elements having an optimized geometry
US11346542B2 (en) * 2019-06-13 2022-05-31 Apple Inc. Electronic device with diffusively illuminated housing portions

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4451872A (en) * 1980-11-26 1984-05-29 Kernforschungsanlage Julich Gesellschaft Mit Beschrankter Haftung Process for the most uniform illumination of a surface by a collimated beam of rays and arrangement for laser diagnostic
US4703405A (en) * 1986-07-17 1987-10-27 Ian Lewin Glare reducing lens
EP1348994A4 (en) * 2000-12-13 2006-04-19 Mitsubishi Rayon Co LIGHT SOURCE DEVICE
EP1852736A1 (en) * 2000-12-13 2007-11-07 Mitsubishi Rayon Co. Ltd. Light source device
US20050094384A1 (en) * 2000-12-13 2005-05-05 Mitsubishi Rayon Co., Ltd. Light source device
US20050105283A1 (en) * 2000-12-13 2005-05-19 Mitsubishi Rayon Co., Ltd. Light source device
US6986599B2 (en) * 2000-12-13 2006-01-17 Mitsubishi Rayon Co., Ltd. Light source device
US7008099B2 (en) 2000-12-13 2006-03-07 Mitsubishi Rayon Co., Ltd. Light source device
US20020114149A1 (en) * 2000-12-13 2002-08-22 Mitsubishi Rayon Co., Ltd. Light source device
US6874902B2 (en) * 2000-12-13 2005-04-05 Mitsubishi Rayon Co., Ltd. Light source device
EP1852735A1 (en) * 2000-12-13 2007-11-07 Mitsubishi Rayon Co. Ltd. Light source device
EP1852737A1 (en) * 2000-12-13 2007-11-07 Mitsubishi Rayon Co. Ltd. Light source device
US20060203490A1 (en) * 2005-03-10 2006-09-14 Honeywell International Inc. Luminaire with a one-sided diffuser
US7690814B2 (en) 2005-03-10 2010-04-06 Honeywell International Inc. Luminaire with a one-sided diffuser
EP2195574B1 (en) * 2007-10-02 2017-06-28 iGUZZINI ILLUMINAZIONE S.p.A. Optical screen for directing light beams with elements having an optimized geometry
US11346542B2 (en) * 2019-06-13 2022-05-31 Apple Inc. Electronic device with diffusively illuminated housing portions

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DE2229011A1 (de) 1972-12-28
FR2142446A5 (it) 1973-01-26
IT956518B (it) 1973-10-10

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