WO1996030786A1 - Arrangements de prismes retro reflechissants assurant une distribution lumineuse uniforme - Google Patents

Arrangements de prismes retro reflechissants assurant une distribution lumineuse uniforme Download PDF

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Publication number
WO1996030786A1
WO1996030786A1 PCT/US1996/001974 US9601974W WO9630786A1 WO 1996030786 A1 WO1996030786 A1 WO 1996030786A1 US 9601974 W US9601974 W US 9601974W WO 9630786 A1 WO9630786 A1 WO 9630786A1
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WO
WIPO (PCT)
Prior art keywords
light
sheeting
microprisms
body portion
retroreflected
Prior art date
Application number
PCT/US1996/001974
Other languages
English (en)
Inventor
Robert B. Nilsen
Original Assignee
Reflexite Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Reflexite Corporation filed Critical Reflexite Corporation
Publication of WO1996030786A1 publication Critical patent/WO1996030786A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/12—Reflex reflectors
    • G02B5/122—Reflex reflectors cube corner, trihedral or triple reflector type
    • G02B5/124—Reflex reflectors cube corner, trihedral or triple reflector type plural reflecting elements forming part of a unitary plate or sheet

Definitions

  • uniform distribution of light energy from retroreflective sheeting is achieved by texturing a surface of the sheeting which is in the path of the light energy.
  • the retroreflective sheeting is formed of a base body with microprisms having a window and three side surfaces.
  • the microprisms extend across the body in a plane adjacent the base body surface.
  • the texturing is formed on a base body surface, in which case the base body should have an index of refraction nl which is different than the index of refraction n2 of the retroreflective microprisms.
  • the preferred texture may range from macro-size (peak to valley height (H) in the order of .0002 inch to .0008 inch) undulations on an otherwise smooth or glossy surface (hereinafter macrotexture) to a combination of macrotexture and micro-size grooves having a peak to valley height (h) in the order of 0.00002 inch to 0.00004 inch.
  • macrotexture peak to valley height
  • h peak to valley height
  • the prism facets, per se may be textured using a chemical etching process, with a similar result.
  • FIG. 1 is a plan view of a portion of a back surface of retroreflective sheeting made in accordance with the invention.
  • FIG. 2 is an enlarged sectional view of the sheeting 10 of FIG. 1 taken along lines A-A.
  • FIG. 3 is a schematic drawing of a typical retroreflected energy pattern generated by prior art microprism material when the prisms are about 0.006 inch on centers.
  • FIG. 4 is a schematic drawing of a retroreflected energy pattern generated by the retroreflective sheeting of the present invention.
  • FIG. 5 is an enlarged partial sectional view of a base body 12 having a combination of micro and macro texturing.
  • FIG. 6 is an enlarged view as in FIG. 5 showing only macro-texturing.
  • FIG. 7 is a plot of light intensity versus observation angle for three samples.
  • FIG. 8 is an enlarged sectional view of sheeting of an alternate embodiment.
  • FIG. 9 is a plan view of an alternate embodiment of the invention wherein the texturing is formed on the prism facets.
  • FIG. 10 is an enlarged view of a single prism of FIG. 9. Detailed Description of the Invention
  • FIGS. 1-4 the invention will now be described in detail in connection therewith.
  • FIG. 1 is a plan view of the retroreflective prism sheeting of the present invention taken from the bottom of the sheeting 10.
  • sheeting refers to relatively thin sheet-like structures, as well as thicker members, laminates and the like, which have a substantially planar front face upon which light rays impinge upon a body portion 12 which is substantially transparent to the light rays.
  • microprisms refers to closely packed or spaced prisms extending in a plane spaced from and generally parallel to and opposite the front face 20 of body 12. The microprisms have a spacing between their apices 15 in the order of 0.002- 0.0025 inches and each is formed with three side surfaces or side facets SI, S2 and S3 disposed along three intersecting planes and a window facet W.
  • a mold is formed with closely spaced microprism cavities therein.
  • a synthetic prism forming transparent resin material is formed on the mold to fill the cavities to form microprisms therein and to provide a continuous body across the surface of the mold.
  • a web of body material 10, having an index of refraction nl which differs from the index of refraction n2 of the microprisms 14 is applied to the microprisms in the mold and adheres thereto as the composite structure is removed from the mold.
  • the bottom, or inner portion, of the base body 12 has a matte finish formed of a composite micro and macro surface texture 16 embossed, etched, or otherwise formed thereon.
  • Body 12 is preferably formed of a vinyl film.
  • the outer surface 20 is formed with a smooth glossy finish.
  • the micro/macro texture 16 on the bottom of the film is sufficient to create scattering of the incident and the retroreflected light resulting in a uniform light intensity retroreflected pattern, as shown in FIG. 4. This scattering is very beneficial since it causes a very uniform beam of highly divergent retroreflected light to be created with greatly improved wide observation angle light distribution. This is illustrated by the prior art pattern shown in FIG. 3, which as previously noted, consists of a maximum central lobe of light 36 surrounded by six lobes of first order diffracted light cones 30 with little or no light formed in the areas between the lobes and the central maxima.
  • the shaded area illustrates the light pattern formed by the present invention, which is substantially uniform over the entire area.
  • the previous lobes of FIG. 3 are shown in dotted lines and are substantially indistinct in the pattern as formed.
  • the refractive index of the materials used for the base body 12 and the material used in the microprisms 14 differ.
  • a hard acrylated epoxy material (n2 equal to about 1.49) is used for the prism structure 14.
  • a 0.10 inch thick vinyl clear film (nl equal to about 1.52) with micro and macro surface texture 16 on the inner side may be used for the body material 12.
  • the overall uniform light distribution maintains its uniformity as the sheeting 10 is rotated to increase the angle of incidence between the incoming light beam and a sample surface, as measured using a laser beam operating at a wavelength of 632.8 nanometers.
  • the light pattern is still very uniform but is slightly elliptical in shape as a result of the elliptical shape of the laser beam as it intersects with the rotated sample and the change in shape of the hexagonal effective aperture of the retroreflecting prisms.
  • Film A is formed of textured vinyl with a matte finish embossed on the outer surface during calendering of the vinyl.
  • the film can be purchased from Renolit Corporation (Germany) under the tradename "Renolit Matte 160/2.”
  • the Film A of FIG. 5 has a random or pseudo-random macro texture of about 0.015 to 0.025 inches with a random or pseudo random micro-texture 16 imposed thereon having a peak to valley high (h) in the order of 0.00002 to 0.00004 inches; whereas the peak to valley height HI of the macro ⁇ texture is in the order of 0.0002 to 0.0008 inches.
  • the film B of FIG. 6 is an alternate choice of a textured film for use as the textured body 12 of the invention.
  • Film B is provided with a random or pseudo- random macro-textured surface texture formed of vinyl material and sold by Renolit Corporation under the tradename Orang 4.
  • the macrotexture 16' has a periodicity P2 of about 0.050 inch to 0.070 inch and a peak to valley height H2 in the order of 0.0002 to 0.0008 inch with no microtexture.
  • FIG. 7 Three curves of Brightness (cd/lux/m 2 ) versus Observation Angle (degrees) are plotted in FIG. 7.
  • Curve A shows the results for sheeting made from Film A
  • Curve B shows the results for similar sheeting with the Film B body substituted
  • Curve C shows the results for a similar test using non-textured standard film.
  • the light intensity for the prior art standard film decreases rapidly between 0.33 degrees and 0.5 degrees, whereas the fall off in intensity is more gradual with film B and even less steep with film A.
  • a metallic reflective coating such as a coating of 600 A of aluminum 40 to the facets 22' of the prism structure 14' (as shown in FIG. 8) .
  • the surrounding area still remains very bright and in this alternative embodiment, no visible secondary maxima 30' remain.
  • the micro/macro texture 16 on the body portion 12 creates a greater divergence of the light.
  • the divergence is 1.42° for a sample formed of .0054 inch pitch, 3° tilt prisms made from acrylated epoxy resin applied to the textured side of a .010 inch vinyl body portion 12.
  • a standard .0054 pitch 3° tilt retroreflective sheeting formed with a .010 inch vinyl body portion with an untextured glossy bottom surface has a divergence of 1.12°. Note that it is not necessary to have the textured side of the body portion 12 located at the interface between the body portion and the microprisms 14. The same scattering effect can be produced by having the textured finish 16' on the outside surface 20 of the body portion 12, as shown in FIG. 8. However, the amplitude of the texture must be much lower. An amplitude which is 1% to 8% of the macro texture amplitude in FIGS. 5 and 6 is preferred.
  • the prism facets SI, S2 and S3 are textured instead of the bottom surface of the base body, with a similar result.
  • the texturing of the facets causes light retroreflected from the facets to be deviated slightly resulting in uniform energy distribution of the retroreflected light.
  • Texturing of the facets can be accomplished by chemical etching, in a random fashion, the prism faces of a plastic (i.e., butyrate) mold used to form the prisms.
  • a plastic i.e., butyrate
  • Yet another preferred approach for texturing the prism facets involves applying a spin coat photoresist application to a nickel mold of the retroreflective sheeting.
  • the resist is then exposed to light from a scanning laser beam projected through a diffuse screen to form a speckled pattern in the resist.
  • the resist is then developed, for example, by a UV bake, and then etched in the exposed areas of the photoresist.
  • the remaining resist is removed leaving a speckled imprint on the mold which can be transferred to the prism facets formed in the mold.
  • the depth of the surface texture, so formed is about one millionth of an inch and the "crater" width of the "speckles" is about .0011 inches.
  • Various synthetic resins may be employed for the cube- corner formulations and for the sheet material including polymers of (alk) acrylic acid esters, such as polymethyl methacrylate and polybutyl acrylate; cellulose esters, such as cellulose acetate polymer, cellulose acetate/butyrate copolymer, and cellulose propionate polymer; vinyl halides, such as polyvinyl fluoride; vinylidene halides, such as polyvinylidene chloride; monovinylidene aromatic hydrocarbon polymers, such as polystyrene and styrene/acrylonitrile copoly ers; ethylenically unsaturated nitriles, such as polyacrylonitrile; polycarbonates; polyesters, such as polyethylene terephthalate; polyphenylene oxide; polysulfones; and polyolefins, such as polyethylene and polypropylene.
  • (alk) acrylic acid esters such as polymethyl methacrylate and polybut
  • Interpolymers of various of the several above-mentioned types of monomers e.g., vinyl chloride/vinyl acetate copolymers, may also be employed, as may be mixtures of polymers.
  • the particular resin formulations selected for the components of the composite structure will vary depending upon the application, the thickness desired for the body member, the desire for flexibility, and the need for achieving interadhesion therebetween.
  • materials which are moisture resistant, ultraviolet resistant and abrasion resistant are particularly advantageously employed at least for the body portion, since that portion is generally exposed to the atmosphere and requires good weathering characteristics.
  • body portion 12 may itself be a laminate of films or sheets of two different synthetic resins, and it may be provided with coatings of appropriate materials subject to the requirement that the mean index of refraction, i.e., composite index, of the composition structure should differ from that of the cube corner prism structure.
  • the resins preferably employed for the body portion include polyvinyl halide, polyethylene terephthalate, polyvinylidene chloride, polycarbonates, polysulfones and cellulose ester polymers.
  • the resins preferably employed for the cube-corner formations comprise (alk) acrylic acid ester resins, acrylic-modified vinyl chloride resins, vinyl chloride/vinyl acetate copolymers, ethylenically unsaturated nitrile resins, monovinylidene aromatic hydrocarbon resins, olefin resins, cellulose ester resins, polysulfone resins, polyphenylene oxide resins and polycarbonates.
  • exemplary combinations for the body portion/cube-corner formations include polyvinyl chloride/acrylic modified polyvinyl chloride; polyvinyl fluoride/polyvinyl chloride; polycarbonate/polycarbonate; polyvinyl chloride/polymethyl methacrylate; polysulfone/polymethyl methacrylate; polysulfone/polyvinyl chloride; and polyethylene terphthalate/polymethyl methacrylate.
  • the sheet material may also provide a valuable degree of protection for the resin of the cube-corner formations, which may exhibit relatively poor stability when the cube-corner formations are reflectively coated and further coated with a lacquer and/or adhesive. These coatings also may act as protective layers, since the body portions will, in many applications, serve as a barrier layer for ultraviolet radiation, vapor, gasses, etc.
  • the cube-corner formations 14 in the illustrated embodiment have a uniform orientation within the array, it is possible to employ a pattern in which certain of the cube-corner formations are disposed in such a manner that their faces are not parallel to any of the faces of the adjacent cube-corner formations. Moreover, certain of the cube-corner formations may be disposed with their apices aligned other than vertically over the center of their respective bases.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Elements Other Than Lenses (AREA)

Abstract

La présente invention décrit un revêtement rétro réfléchissant et un procédé de fabrication et d'utilisation d'un tel revêtement dont le corps principal est formé de microprismes séparés par des espaces étroits. Les microprismes comportent des facettes fenêtres s'étendant à travers la portion du corps dans un plan, avec des facettes réfléchissantes s'étendant des facettes fenêtres jusqu'aux sommets. Soit les surfaces du corps principal soit les facettes latérales comportent une texture qui dévie le chemin lumineux entrant et/ou se réfléchissant depuis les prismes afin d'assurer une distribution lumineuse uniforme.
PCT/US1996/001974 1995-03-27 1996-02-14 Arrangements de prismes retro reflechissants assurant une distribution lumineuse uniforme WO1996030786A1 (fr)

Applications Claiming Priority (2)

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US41086495A 1995-03-27 1995-03-27
US08/410,864 1995-03-27

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Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998012581A1 (fr) * 1996-09-23 1998-03-26 Reflexite Corporation Materiau retroreflechissant comprenant des microprismes presentant une courbe concave dans la face de la base
US5763049A (en) * 1996-04-30 1998-06-09 Minnesota Mining And Manufacturing Company Formed ultra-flexible retroreflective cube-corner composite sheeting with target optical properties and method for making same
WO1998059266A1 (fr) * 1997-06-25 1998-12-30 Reflexite Corporation Structures prismatiques retroreflechissantes configurees et moules permettant de les produire
US5898523A (en) * 1997-07-02 1999-04-27 Minnesota Mining & Manufacturing Company Tiled retroreflective sheeting composed of highly canted cube corner elements
WO1999028770A1 (fr) * 1997-12-01 1999-06-10 Reflexite Corporation Feuille retroreflechissante a orientations multiples
US5940212A (en) * 1997-10-30 1999-08-17 3M Innovative Properties Company Cube corner article with altered inactive areas and method of making same
US6120879A (en) * 1997-09-25 2000-09-19 3M Innovative Properties Company Dual use reflective article
WO2002101423A2 (fr) 2001-06-11 2002-12-19 Avery Dennison Corporation Retroreflecteur dote d'une divergence controlee par le procede d'ondulation de rainures
US6575584B1 (en) 1999-05-28 2003-06-10 Universite De Liege Light guiding plate with internal micro-prisms
US6623824B1 (en) 1999-01-29 2003-09-23 3M Innovative Properties Company Method for making a microreplicated article using a substrate comprising a syndiotactic vinyl aromatic polymer
US6896757B2 (en) * 2001-02-09 2005-05-24 Avery Dennison Corporation Rear projection screens and light filters with conformable coatings and methods of making the same
WO2007040725A1 (fr) 2005-09-26 2007-04-12 Avery Dennison Corporation Feuille rétroréfléchissante à couche d’amélioration de divergence
WO2012166448A1 (fr) 2011-05-31 2012-12-06 3M Innovative Properties Company Articles rétroréfléchissants ayant des coins cubiques composites et procédés de fabrication de ceux-ci
US8371703B2 (en) 2008-10-22 2013-02-12 3M Innovative Properties Company Retroreflective sheeting
US9415539B2 (en) 2011-05-31 2016-08-16 3M Innovative Properties Company Method for making microstructured tools having discontinuous topographies, and articles produced therefrom
US9523919B2 (en) 2011-05-31 2016-12-20 3M Innovative Properties Company Methods for making differentially pattern cured microstructured articles
US10082609B2 (en) 2009-11-12 2018-09-25 3M Innovative Properties Company Irradiation marking of retroreflective sheeting
CN113635495A (zh) * 2021-10-15 2021-11-12 福建夜光达科技股份有限公司 具有平顶微棱镜阵列的反光材料模具及其制备方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100864321B1 (ko) * 2007-06-19 2008-10-20 제일모직주식회사 프리즘 계곡부위에 무정형의 돌기형상을 가지는 광확산체를포함하는 디퓨져 프리즘 시트 및 이를 이용한액정표시장치

Citations (2)

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Publication number Priority date Publication date Assignee Title
US5171624A (en) * 1990-06-01 1992-12-15 Reflexite Corporation Retroreflective microprismatic material and method of making same
WO1995003558A1 (fr) * 1993-07-19 1995-02-02 Reflexite Corporation Structure retroreflechissante

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5171624A (en) * 1990-06-01 1992-12-15 Reflexite Corporation Retroreflective microprismatic material and method of making same
WO1995003558A1 (fr) * 1993-07-19 1995-02-02 Reflexite Corporation Structure retroreflechissante

Cited By (33)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6258443B1 (en) 1994-09-28 2001-07-10 Reflexite Corporation Textured retroreflective prism structures and molds for forming same
US6770225B2 (en) 1994-09-28 2004-08-03 Reflexite Corporation Textured retroreflective prism structures and molds for forming same
US5763049A (en) * 1996-04-30 1998-06-09 Minnesota Mining And Manufacturing Company Formed ultra-flexible retroreflective cube-corner composite sheeting with target optical properties and method for making same
WO1998012581A1 (fr) * 1996-09-23 1998-03-26 Reflexite Corporation Materiau retroreflechissant comprenant des microprismes presentant une courbe concave dans la face de la base
WO1998059266A1 (fr) * 1997-06-25 1998-12-30 Reflexite Corporation Structures prismatiques retroreflechissantes configurees et moules permettant de les produire
US5898523A (en) * 1997-07-02 1999-04-27 Minnesota Mining & Manufacturing Company Tiled retroreflective sheeting composed of highly canted cube corner elements
US6120879A (en) * 1997-09-25 2000-09-19 3M Innovative Properties Company Dual use reflective article
US5940212A (en) * 1997-10-30 1999-08-17 3M Innovative Properties Company Cube corner article with altered inactive areas and method of making same
WO1999028770A1 (fr) * 1997-12-01 1999-06-10 Reflexite Corporation Feuille retroreflechissante a orientations multiples
US6457835B1 (en) 1997-12-01 2002-10-01 Reflexite Corporation Multi-orientation retroreflective structure
US6036322A (en) * 1997-12-01 2000-03-14 Reflexite Corporation Multi-orientation retroreflective structure
US6623824B1 (en) 1999-01-29 2003-09-23 3M Innovative Properties Company Method for making a microreplicated article using a substrate comprising a syndiotactic vinyl aromatic polymer
US6575584B1 (en) 1999-05-28 2003-06-10 Universite De Liege Light guiding plate with internal micro-prisms
US6896757B2 (en) * 2001-02-09 2005-05-24 Avery Dennison Corporation Rear projection screens and light filters with conformable coatings and methods of making the same
WO2002101423A2 (fr) 2001-06-11 2002-12-19 Avery Dennison Corporation Retroreflecteur dote d'une divergence controlee par le procede d'ondulation de rainures
EP1423258A2 (fr) * 2001-06-11 2004-06-02 Avery Dennison Corporation Retroreflecteur dote d'une divergence controlee par le procede d'ondulation de rainures
US7427139B2 (en) 2001-06-11 2008-09-23 Avery Dennison Corporation Retroreflector with controlled divergence made by the method of groove undulation
EP1423258A4 (fr) * 2001-06-11 2007-04-18 Avery Dennison Corp Retroreflecteur dote d'une divergence controlee par le procede d'ondulation de rainures
WO2007040725A1 (fr) 2005-09-26 2007-04-12 Avery Dennison Corporation Feuille rétroréfléchissante à couche d’amélioration de divergence
US9878507B2 (en) 2008-10-22 2018-01-30 3M Innovative Properties Company Retroflective sheeting
US8371703B2 (en) 2008-10-22 2013-02-12 3M Innovative Properties Company Retroreflective sheeting
US8783879B2 (en) 2008-10-22 2014-07-22 3M Innovative Properties Company Retroreflective sheeting
US10618234B2 (en) 2008-10-22 2020-04-14 3M Innovative Properties Company Retroreflective sheeting
US10509148B2 (en) 2009-11-12 2019-12-17 3M Innovative Properties Company Irradiation marking of retroreflective sheeting
US10082609B2 (en) 2009-11-12 2018-09-25 3M Innovative Properties Company Irradiation marking of retroreflective sheeting
US9523919B2 (en) 2011-05-31 2016-12-20 3M Innovative Properties Company Methods for making differentially pattern cured microstructured articles
US9415539B2 (en) 2011-05-31 2016-08-16 3M Innovative Properties Company Method for making microstructured tools having discontinuous topographies, and articles produced therefrom
US10401541B2 (en) 2011-05-31 2019-09-03 3M Innovative Properties Company Article having composite lenticular microstructures and method of making
WO2012166448A1 (fr) 2011-05-31 2012-12-06 3M Innovative Properties Company Articles rétroréfléchissants ayant des coins cubiques composites et procédés de fabrication de ceux-ci
US9366790B2 (en) 2011-05-31 2016-06-14 3M Innovative Properties Company Retroreflective articles having composite cube-corners and methods of making
US11292159B2 (en) 2011-05-31 2022-04-05 3M Innovative Properties Company Method for making microstructured tools having discontinuous topographies, and articles produced therefrom
CN113635495A (zh) * 2021-10-15 2021-11-12 福建夜光达科技股份有限公司 具有平顶微棱镜阵列的反光材料模具及其制备方法
CN113635495B (zh) * 2021-10-15 2022-01-04 福建夜光达科技股份有限公司 具有平顶微棱镜阵列的反光材料模具及其制备方法

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