WO2016043988A1 - Réflecteurs à trous micro-perforés dans des plaques de guidage de lumière - Google Patents

Réflecteurs à trous micro-perforés dans des plaques de guidage de lumière Download PDF

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Publication number
WO2016043988A1
WO2016043988A1 PCT/US2015/048473 US2015048473W WO2016043988A1 WO 2016043988 A1 WO2016043988 A1 WO 2016043988A1 US 2015048473 W US2015048473 W US 2015048473W WO 2016043988 A1 WO2016043988 A1 WO 2016043988A1
Authority
WO
WIPO (PCT)
Prior art keywords
light
holes
substrate
article
coupled
Prior art date
Application number
PCT/US2015/048473
Other languages
English (en)
Inventor
Jacques Gollier
Kristopher Allen WIELAND
Original Assignee
Corning Incorporated
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 Corning Incorporated filed Critical Corning Incorporated
Publication of WO2016043988A1 publication Critical patent/WO2016043988A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0038—Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0058—Means for improving the coupling-out of light from the light guide varying in density, size, shape or depth along the light guide
    • G02B6/0061—Means for improving the coupling-out of light from the light guide varying in density, size, shape or depth along the light guide to provide homogeneous light output intensity
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0066—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form characterised by the light source being coupled to the light guide

Definitions

  • Described herein are articles and methods for improving illumination and light propagation in transparent materials.
  • the articles and methods described herein are useful in the design of light guide plates used in electronics devices, such as televisions and monitors.
  • LGP light guide plate
  • the LED light is coupled into the LGP from at least one edge of the LGP (the coupling edge) and light is extracted as it propagates by diffusing structures, typically white paint or surface scattering components, on the LGP.
  • the edge- lit LGP present significant advantages over direct illumination, where a square array of LEDs is used to directly illuminate the panel, because the panel can be made extremely thin.
  • direct illumination has over edge-lit displays is that every single LED of the array can be driven separately so that dimmer areas into images can be illuminated with less light by dimming some of the LED's.
  • local dimming This is referred to as "local dimming" which provides savings in energy consumption and also improves image contrast, especially in the black regions of a picture. While local dimming has also been introduced into edge-lit LGPs, the efficiency is relatively low and the improvement in image contrast is less effective since the light emitted by individual LED's rapidly expands into the LGP as light propagates, providing less discrimination between the pixels. Simply put, the current methods of local dimming fail to satisfy the needs of the manufacturers and customers in the display industry.
  • a first aspect comprises an article comprising a light transmittive substrate that has two approximately parallel major surfaces; at least one light element coupled to the substrate and introducing light into the substrate; and a series of holes in the substrate that are approximately orthogonal to the parallel major surfaces and are aligned in such a way as to act as a light guide for light from the coupled light element.
  • the holes have a diameter from about 200 nm to about 200 ⁇ .
  • the holes have a diameter from about 500 nm to about 100 ⁇ .
  • the series of holes comprises two or more structure lines.
  • the holes comprising each structure line are on or scattered in an ordered or random fashion around a demarcation line.
  • the holes have a face that is defined by the shape of the hole on one or both of the approximately parallel major surfaces of the light transmittive substrate and a cross section defined by the shape of the hole when viewed orthogonal to the approximately parallel major surfaces of the light transmittive substrate.
  • the face of the hole is approximately circular.
  • the cross section of the hole is cylindrical, cone-shaped, or waisted.
  • Embodiments of the first aspect may further comprise one or more light extraction features.
  • the one or more light extraction features may comprise one or more of spherical holes, laser formed waveguides, internal damage spots, internal structures with indices of refraction different than the glass sheet, surface modifications, bumps, pits, or nanoparticles or quantum dots.
  • Another embodiment further comprises a second light element coupled to the substrate and introducing light into the substrate, wherein the second light element is coupled orthogonally to the first light element; and a second series of holes in the substrate that are approximately orthogonal to the parallel major surfaces and are aligned in such a way as to act as a light guide for light from the second coupled light element.
  • Another embodiment comprises a backlight unit comprising any of the articles above or alternatively, a display comprising any of the articles above.
  • a second aspect comprises a lightguide plate comprising a light transmittive substrate that has two approximately parallel major surfaces; at least one light element coupled to the substrate and introducing light into the substrate; and a series of holes in the substrate that are approximately orthogonal to the parallel major surfaces and are aligned around the periphery of the edges of the substrate no coupled to the light element and wherein the holes are aligned in such a way as to act as a light guide for light for the coupled light element.
  • Embodiments of this aspect comprise backlight units or displays that comprise the aspect.
  • FIG. 1 is a simulation of the non-collimated expansion of light from a LED as it travels through a waveguide.
  • FIG. 2 is a simulation of the non-collimated light from an LED in a waveguide, where the light is guided by a prism array that has been laminated to the light guide on one of the major planes.
  • FIG. 3 shows the effect of a hole simulated as a cylinder of air inside the glass substrate.
  • the ray simulation shows that the hole act like light scattering center which angularly re-distribute the light in the plane of the LGP.
  • FIG. 4A shows cross-sections of the holes that may be incorporated into the LGP.
  • Fig. 4B shows additional features that may be incorporated with embodiments.
  • FIG. 5 is a simulation of a light guide where a light "channel" is created by lines of micro-holes 510 and 511 in the waveguide (orthogonal to the major planes). As can be seen, light emitted by a single LED remains confined. Two lines of two rows (520 and 521) of holes were created, where the lines were 50 mm apart and the rows were 1 mm apart. The holes were 60 ⁇ in diameter and placed 125 ⁇ apart (center-to-center (also referred to as "pitch”)).
  • FIG. 6 is another simulation of a light guide where a light "channel" is created by lines of micro-holes in the waveguide where two sets of lines are running orthogonal to each other (610 and 620) and intersect at square 630.
  • FIG. 7A is a diagram showing the experimental setup for the picture of FIG. 7B.
  • FIG. 7A and FIG. 7B show light from an LED being coupled into a glass light guide plate having two single lines (50 mm apart) of 1 ⁇ holes drilled orthogonally into the plate and spaced 5 ⁇ apart center-to-center. At 600 mm from the LED, the back of the light guide plate was painted with a white ink to allow for light extraction.
  • Fig. 8 shows an alternative embodiment where the holes in the LGP are drilled along the periphery of three sides of the LGP - the side nearest the edge-lit LED side not having holes - to scatter the light within the LGP and act as substitutes for diffusing reflectors.
  • Fig. 9 shows an alternative embodiment where the holes are placed randomly about a line of demarcation (910) rather than in a more exact line (920). Such an embodiment may avoid issues of weakening the LGP or creating visible light lines in the LGP.
  • Ranges may be expressed herein as from “about” one particular value, and/or to "about” another particular value. When such a range is expressed, another aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.
  • edge-lit LCD backlights offer significant advantages in making displays thinner. However, they have traditionally suffered from issues of image contract and energy usage because local dimming has been unavailable or less effective than in directly illuminated LCD displays.
  • An example of an edge-lit LGP with a single LED is shown in FIG. 1. As can be seen in the figure, light from the LED rapidly expands over 400 mm to light most of the far side of the LGP - in fact, spreading to a width greater than the length. Therefore, in the case of an edge-lit display, simply individually manipulating the light output of the LEDs will not give same the local dimming effect shown in direct-lit displays.
  • FIG. 2 again shows a single LED coupled to a LGP.
  • the light propagation is confined through the use of prism arrays that are laminated to one or both of the top and bottom surfaces of the LGP.
  • the light remains more confined, having a width of about 150 mm at 400 mm distance, but still shows significant divergence.
  • such an approach may be somewhat expensive for glass light guides since this will require to laminate large size films on the LGP and lamination is a relatively expensive process.
  • a first aspect described herein relates to alternative designs and technologies that provide improved local dimming in edge-lit displays.
  • a number of technologies have been developed to drill high precision micro-holes into glass. Hole diameters range from a 1 ⁇ when glass is only laser exposed to over 100 ⁇ when the glass is both laser exposed and etched.
  • FIG. 3 shows the effect of a hole, simulated as a cylinder of air, inside a glass waveguide where the blue lines simulate light impinging on the cylinder.
  • Fig. 3 shows that the holes act like light scattering centers and angularly redistribute the light in the plane of the LGP.
  • the major advantage of cylindrical geometry is that the angular scattering function is highly nonsymmetric as opposed, for instance, to a spherical configuration - meaning that light is only scattered in the plane of the LGP and the scattering centers do not add additional scattering components in the direction of the LGP thickness (i.e., scattering light out of the glass plane as a spherical scattering center would).
  • the consequence is that, although light gets scattered at very high angle (in the plane of the LGP), it is still guided in the LGP. In other words, holes do not significantly extract light.
  • the cylindrical holes do not add a light extraction element, it is possible to and advantageous to use other shaped holes.
  • 4A shows example cross-sections of alternative hole designs that are contemplated.
  • 410 is a cylindrical hole
  • 420 shows a tapering cylinder
  • 430 is a hour glass, or waisted-type cylinder
  • 440 provides an exponentially decaying-type structure.
  • the different types of hole structures may be used alone or in combination.
  • the advantages of non-cylindrical structures is that they may be useful in targeted scattering of the light out of the LGP at certain angles or at certain locations, especially when used in combination with cylindrical scattering holes.
  • the hole structures can be used in combination with other scattering features used in LGP and backlights, such as those examples shown in FIG.
  • 4B - spherical holes laser formed waveguides, internal damage spots, or other internal structures with indices of refraction different than the glass sheet (450), surface modifications, such as bumps (460) or pits (470), or nanoparticles or quantum dots (480), either in the glass or on one or more surfaces.
  • the holes act as strong scattering centers, they act and can be used as reflectors inside glass. In other words, if a region of the LGP has a high enough hole density, light will not penetrate past that region, but instead will be backscattered. This allows for controlling and confining the in some regions of the LGP and provides for a local dimming function. According to optical modeling and experiments, the minimum condition for obtaining reflectivity is:
  • N is the amount of holes per meter in the direction of light propagation
  • FIG. 5 shows a simulation of a light guide where a light channel is created by lines of micro-holes.
  • a single LED 501
  • lines 510 and 511 comprise two rows of holes, rows 520 and 521, 1 mm apart, that are made up of 60 ⁇ holes spaced 125 ⁇ apart, center-to-center. While shown as being the same size, holes can optionally have different diameters and densities which can change as a function of proximity to the LED or due to other parameters known to one of skill in the art.
  • This concept can also be extended to two dimensional "light channels" in the case where the display has LED's on more than one edge.
  • the local dimming can be done in two dimensions orthogonal to each other.
  • Lines 620 show the scattering holes in the horizontal direction, while lines 610 highlight the scattering holes in the vertical.
  • LEDs (601 and 602) are placed inside lines 610 and 620, respectively, and square 630 is the overlap of the two LEDs on the substrate.
  • FIG. 8 Another aspect described herein, shown in FIG. 8, is the use of holes in the LGP that are drilled along the periphery of three sides of the LGP (shown as dotted lines in FIG. 8) - the side nearest the edge-lit LED side not having holes - to scatter the light within the LGP and act as substitutes for diffusing reflectors.
  • Light guide designs often consist in using a transparent light guiding sheet illuminated from one side.
  • a diffusing paper like diffusing tape is often attached to the 3 other edges of the LGP to minimize light leakage from those edges.
  • those reflectors are usually of relatively poor efficiency since they are generally Lambertian-like diffusers and will scatter a significant amount of light out of the light guide.
  • optimization may be related to any number of criteria that are important in the LGP, backlight unit, or the display itself.
  • the holes may be placed to optimize light guiding, LGP strength, light extraction, color shift, etc.
  • placing the holes in a line (920) may pose an issue for LGP strength and potentially lead to cracking of the substrate upon stress or repeated thermal cycles. Plus, a line of holes will encourage any crack formed to propagate meaning that this can generate reliability issues.
  • the holes may not be perfect cylinders, they can partly scatter the light in the direction perpendicular to the light guide which can create light lines or other artifacts in the image.
  • lines 910 are termed “demarcation lines,” and describe the center or average line formed by the linear or scattered holes that form a waveguide.
  • a “structure line,” as used herein, is described by the line shape defined by the dotted lines 940 and 941 and is a description of the rough "line” of holes that form a waveguide feature.
  • FIG. 7A is a schematic diagram showing the experimental setup shown FIG. 7B.
  • FIG. 7A and FIG. 7B show light from an LED being coupled into a glass light guide plate having two single lines (50 mm apart) of 1 ⁇ holes drilled orthogonally into the plate and spaced 5 ⁇ apart center-to-center.
  • the back of the light guide plate was painted with a white ink to allow for light extraction.
  • the white paint clearly shows the intensity increase in the center section where the LED is being guided by the cylindrical holes. The effectiveness of the holes could be increased by optimizing the hole size, spacing and placing multiple rows of holes along each line.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Planar Illumination Modules (AREA)
  • Light Guides In General And Applications Therefor (AREA)

Abstract

La présente invention concerne des articles et des procédés pour améliorer l'éclairage et la propagation de la lumière dans des matériaux transparents. En particulier, les articles et les procédés décrits sont utiles dans la conception de plaques de guidage de la lumière utilisées dans des dispositifs électroniques, tels que des télévisions et des moniteurs. Le guidage de la lumière est effectué par l'intermédiaire de l'incorporation de séries de trous dans le guide de lumière pour commander et diriger la lumière à l'intérieur de la structure.
PCT/US2015/048473 2014-09-15 2015-09-04 Réflecteurs à trous micro-perforés dans des plaques de guidage de lumière WO2016043988A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201462050313P 2014-09-15 2014-09-15
US62/050,313 2014-09-15

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Publication Number Publication Date
WO2016043988A1 true WO2016043988A1 (fr) 2016-03-24

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI566016B (zh) * 2016-05-20 2017-01-11 恆顥科技股份有限公司 直下式背光模組
EP3267247A1 (fr) * 2016-07-06 2018-01-10 LG Electronics Inc. Unité de rétroéclairage pour afficheur
WO2018152300A1 (fr) * 2017-02-16 2018-08-23 Corning Incorporated Procédés de fabrication d'un article en verre à surface structurée
WO2018152295A1 (fr) * 2017-02-16 2018-08-23 Corning Incorporated Unité de rétroéclairage à gradation unidimensionnelle
US11186518B2 (en) 2017-02-16 2021-11-30 Corning Incorporated Methods of making a glass article with a structured surface

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090190070A1 (en) * 2006-07-24 2009-07-30 Takayuki Nagata Planar illumination device and liquid crystal display device adopting the same
US20110013416A1 (en) * 2009-07-20 2011-01-20 Kim Youngchan Light guide plate and display apparatus having the same
US20120105503A1 (en) * 2010-11-02 2012-05-03 Kabushiki Kaisha Toshiba Illumination device and liquid crystal display device
US20120162576A1 (en) * 2010-10-28 2012-06-28 Norihiro Sakamoto Surface light source device and lcd unit

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090190070A1 (en) * 2006-07-24 2009-07-30 Takayuki Nagata Planar illumination device and liquid crystal display device adopting the same
US20110013416A1 (en) * 2009-07-20 2011-01-20 Kim Youngchan Light guide plate and display apparatus having the same
US20120162576A1 (en) * 2010-10-28 2012-06-28 Norihiro Sakamoto Surface light source device and lcd unit
US20120105503A1 (en) * 2010-11-02 2012-05-03 Kabushiki Kaisha Toshiba Illumination device and liquid crystal display device

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI566016B (zh) * 2016-05-20 2017-01-11 恆顥科技股份有限公司 直下式背光模組
EP3267247A1 (fr) * 2016-07-06 2018-01-10 LG Electronics Inc. Unité de rétroéclairage pour afficheur
CN107589483A (zh) * 2016-07-06 2018-01-16 Lg 电子株式会社 背光单元和包括背光单元的显示装置
US10551667B2 (en) 2016-07-06 2020-02-04 Lg Electronics Inc. Backlight unit and display device including the same
WO2018152300A1 (fr) * 2017-02-16 2018-08-23 Corning Incorporated Procédés de fabrication d'un article en verre à surface structurée
WO2018152295A1 (fr) * 2017-02-16 2018-08-23 Corning Incorporated Unité de rétroéclairage à gradation unidimensionnelle
US11186518B2 (en) 2017-02-16 2021-11-30 Corning Incorporated Methods of making a glass article with a structured surface
US11287560B2 (en) 2017-02-16 2022-03-29 Corning Incorporated Backlight unit with one dimensional dimming

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Publication number Publication date
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