WO2001002772A1 - Ensemble d'affichage dote d'un guide optique frontal - Google Patents

Ensemble d'affichage dote d'un guide optique frontal Download PDF

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Publication number
WO2001002772A1
WO2001002772A1 PCT/US1999/026078 US9926078W WO0102772A1 WO 2001002772 A1 WO2001002772 A1 WO 2001002772A1 US 9926078 W US9926078 W US 9926078W WO 0102772 A1 WO0102772 A1 WO 0102772A1
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WO
WIPO (PCT)
Prior art keywords
light guide
light
extractors
display
display assembly
Prior art date
Application number
PCT/US1999/026078
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English (en)
Inventor
Theodore W. Hodapp
Original Assignee
3M Innovative Properties Company
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 3M Innovative Properties Company filed Critical 3M Innovative Properties Company
Priority to AU14682/00A priority Critical patent/AU1468200A/en
Publication of WO2001002772A1 publication Critical patent/WO2001002772A1/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
    • G02B6/0036—2-D arrangement of prisms, protrusions, indentations or roughened surfaces

Definitions

  • the present invention pertains to front-lit display assemblies that have front light guides with edge-mounted light sources.
  • Display systems that illuminate the display from the viewing side are known as front-lit displays. These displays commonly utilize ambient light from the surroundings to light reflective or transflective liquid crystal displays (LCDs). As disclosed, for example, in U.S. Pat. Nos. 5,477,239; 5,608,550; and 4,373,282, and in Japanese Laid-Open Patent Application 6-324331, displays can also be lit from the front by using an internal or supplemental light source mounted at an edge of the display.
  • LCDs liquid crystal displays
  • Front-lit displays that utilize edge-mounted internal lighting typically include a light guide that distributes light across the display panel and redirects the light toward the display for illumination.
  • internally lit front-lit displays often appear hazy or washed-out relative to back-lit transmissive displays.
  • the hazy, low contrast appearance of front-lit displays can generally be attributed, at least in part, to light guides that inefficiently extract light and/or scatter or redirect light in undesired directions. For example, light injected into a light guide of a front-lit display might be scattered toward the viewer without first illuminating the display panel. Undesired light scattering can greatly reduce display contrast, for example, by making dark areas appear brighter than they otherwise would appear if the light guide was not present.
  • a display assembly utilizes a front light guide that includes light extractors that can have spacings, aspect ratios, shapes, and orientations selected to improve display performance characteristics such as contrast modulation, light extraction efficiency, and extraction ratio. By improving these performance characteristics, haze can be reduced while display contrast and clarity are increased.
  • the present invention provides a display assembly that includes: (a) a display panel that has a viewable surface, (b) a light guide that has a substantially planar front surface oriented away from the display panel, a back surface that has a plurality of extractors extending toward the display panel, and a light input surface located on an edge of the light guide positioned between the front and back surfaces, and (c) a light source optically coupled to the light input surface for injecting light into the light guide, wherein the light guide exhibits a contrast modulation that is at least about 0.5 for an at least 90% diffusely reflective white surface and an at most 10% diffusely reflective black surface, the contrast modulation being substantially uniform for viewing angles up to about 60°.
  • the present invention provides a display assembly that includes: (a) a display panel that has a viewable surface, (b) a light guide that has a substantially planar front surface oriented away from the display panel, a back surface that has a plurality of extractors extending toward the display panel, and a light input surface located on an edge of the light guide positioned between the front and back surfaces, and (c) a light source optically coupled to the light input surface for injecting light into the light guide, wherein the extractors have height-to-width aspect ratios that are at least about
  • FIG. 1 is a schematic cross-sectional view of a display assembly having a front light guide
  • FIG. 2 is a schematic cross-sectional view of a front light guide
  • FIG. 3 is a horizontal cross-sectional view of extractors on a front light guide.
  • FIG. 1 shows a front lit display assembly 100 that has a front light guide 10.
  • Front light guide 10 has an optically-coupled light source 12 mounted near an edge 11. Under conditions of sufficient ambient light, light from an external source 22 can pass through light guide 10 and illuminate display panel 20. Under conditions where more than ambient light is desired to illuminate the display panel, light from edge-mounted light source 12 can be used. Light emitted from the edge-mounted light source 12 can be injected into light guide 10 and can propagate though the light guide via total internal reflection. Preferably, the light from light source 12 is injected into light guide 10 within a cone of angles that satisfy the conditions for total internal reflection inside the light guide.
  • Light guide 10 can be made of a material that is substantially transmissive of light in a desired wavelength range (e.g., visible light). Suitable materials include glass and substantially transparent polymeric materials such as acrylate-based polymers, polycarbonates, or other substantially transparent materials. For example, some polyurethanes can be used that are substantially transparent to visible light, as disclosed in co-pending, commonly assigned U.S. Patent Application 09/026,836 entitled "Method and Apparatus for Seamless Microreplication Using an Expandable Mold". Light guide 10 can be rigid or flexible, depending on the material that is used. Light guide 10 can have dimensions that vary widely depending on the application, and often depending on the size of the display panel.
  • the lateral dimensions of the light guide are roughly equal to the lateral dimensions of the display panel, although light guides that are larger or smaller than the display panel can be used (e.g., when only a specific portion or portions of the display panel are to be illuminated).
  • Light guides of the present invention can have lateral dimensions that range from a few centimeters or less to one or more meters. Because thin display assemblies are generally desirable, the thickness of the light guide (i.e., the dimension of the light guide perpendicular to the lateral dimensions) is preferably much smaller than the lateral dimensions of the display and yet large enough to provide the light guide with sufficient physical integrity. Light guide thicknesses typically vary from tenths of millimeters or less to one or more centimeters.
  • Light guides of the present invention can be substantially plate-like (i.e., the front and back surfaces are substantially parallel resulting in a substantially uniform thickness, as in FIG. 1), or the light guides can vary in thickness.
  • a light guide can be wedge-shaped.
  • FIG. 2 shows an example of a generally wedge-shaped light guide 10' where the thickness of the light guide decreases with distance from light input surface 11. Examples of wedge-shaped light guides are disclosed in U.S. Pat. Nos. 5,499,165 and 5,237,641. Other configurations in which the thickness of the light guide varies are also possible. For example, the thickness of the light guide can decrease from all edges toward the center of the light guide.
  • Another example includes a pseudo-wedge configuration where one surface of the light guide is shaped to have a repeating pattern that first slopes toward the opposing surface of the light guide at a shallow angle and then abruptly steps up.
  • the profile of the light guide is locally wedge- shaped while the overall shape of the light guide can remain generally plate-like or can also be wedge-shaped.
  • Light guides of the present invention can include one or more light input surfaces located on one or more edges of the light guide.
  • Light input surfaces can be used for optical coupling of the light guide with edge-mounted light sources.
  • mirrors or other wholly or partially reflective (diffusely or specularly) films or coatings can be disposed on light input surfaces of the light guide. Reflective edges can help to recycle light that might otherwise escape from the edges of the light guide.
  • wedge-shaped configurations commonly have a light source 12 coupled to an edge 11 of the light guide 10' where the thickness is greater.
  • extractors 14 can be provided that extend from back surface 8 of front light guide 10. Extractors 14 enable extraction of light from inside light guide 10 toward a display panel 20 placed adjacent the back surface 8 of the light guide 10. Extractors 14 have side surfaces 18 which extend from the back surface 8 of light guide 10 to a termination surface 16. The termination surface 16 of each extractor is preferably substantially parallel to back surface 8 of the light guide. Side surfaces 18 of extractors 14 can be substantially perpendicular to back surface 8 of the light guide, or side surfaces 18 can make wall angles of up to 15° with an axis normal to back surface 8 of the light guide. The angularity of the side surfaces can also affect properties such as extraction efficiency and extraction ratio in the display, as discussed in more detail hereinafter.
  • Extractors 14 can be column-like, post-like, and/or rib-like protuberances that extend from the back surface 8 of light guide 10.
  • the sizes of extractors 14 compared to light guide 10 in FIG. 1 have been greatly exaggerated for illustration.
  • Light extraction from light guide 10 can occur when light propagated in the light guide becomes incident on a side surface 18 of an extractor 14 and is at least partially refracted out of the light guide toward display panel 20. Extracted light that illuminates display panel 20 can be directed back through the light guide toward an observer.
  • extractors 14 preferably have heights, h, (measured perpendicular to the back surface of the light guide) and widths, w, (measured parallel to the back surface of the light guide at the back surface of the light guide) that can range from about 5 ⁇ m to 1000 ⁇ m for small to mid-sized displays (e.g., lateral display dimensions up to several tens of centimeters) or from about 5 ⁇ m to 10 mm or more for large display (e.g., lateral display dimensions of 1 meter or more). In general, smaller extractors are preferred for smaller pixel sizes and higher resolutions.
  • the shapes of the extractor columns can vary depending on the application.
  • the extractors can have any of a variety of shapes including circles, regular polygons, and elongated shapes such as ellipses, rhombi, elongated rectangular shapes, and others.
  • the shape, position, and orientation of extractors on the light guide can affect the direction and efficiency of light extraction.
  • the height-to- width aspect ratio of the extractors can also be an important property in determining light guide performance. Extractor heights are preferably large enough as compared to extractor widths so that internally reflected light rays that enter extractors can be extracted from extractor side surfaces without significantly interacting with extractor termination surfaces.
  • the aspect ratio of the extractors should be greater than l/tan( ⁇ c ) (where ⁇ c is the critical angle for total internal reflection) so that light rays entering extractors will be incident on extractor side surfaces.
  • FIG. 3 shows a horizontal cross-section of an array of rhombus- shaped extractors 14' arranged in a generally hexagonal array.
  • the maximum effective width of the extractors is W LI -
  • the maximum effective width of the extractors is W L2
  • Effective widths of extractors can also be measured relative to other directions of interest, such as along a spacing direction (a direction along which the distance between neighboring extractors is measured).
  • a spacing direction a direction along which the distance between neighboring extractors is measured.
  • FIG. 3 indicates the center-to-center spacing S between two adjacent extractors.
  • the spacing S is about three times the effective width s of the extractors measured along the spacing direction.
  • the term "effective width” as used herein refers to a width of an extractor measured in a direction of interest (e.g., a net direction of light propagation in the plane of the light guide, a spacing direction, etc.).
  • the concept of effective width and, analogously, effective aspect ratio are general and can be extended to any particular direction of interest along the light guide and to extractors that have any particular horizontal cross-section and/or arrangement.
  • the extractors on the light guide can be of the same material as the light guide or of a different material.
  • the extractors are made of a transparent material that has an index of refraction at least as high as the index of refraction of the material of the light guide.
  • the extractors can be fabricated along with the light guide by conventional techniques such as molding, embossing, cast and cure methods, etching, or direct diamond turning of the light guide material.
  • the extractors can also be fabricated separately, either as individual elements or together on a thin layer, and subsequently adhered to the light guide.
  • Extractors out of a different material than the light guide can offer advantages. For example, extractors that have an index of refraction higher than that of the light guide can refract light from the extractor side surfaces at an angle closer to perpendicular with the display panel than for extractors that have lower indices of refraction. This can cause more light to reach the viewer, resulting in a brighter display.
  • extractors made of a material different from the body of the light guide adds an interface between the light guide and the extractors, which can cause scattering of light and Fresnel reflections, resulting in decreased efficiency.
  • Display panel 20 can be any suitable object that has a viewable surface capable of being illuminated from the front.
  • Exemplary display panels include: reflective or transflective electronic displays such as LCDs and other reflective displays; diffusely reflective passive objects such as pictures, maps, billboards, and the like; diffusely reflective active objects or changeable displays such as electronic paper or similar displays such as those described in U.S. Pat. Nos. 5,777,782; 5,808,783; 5,892,497; and 5,894,367, and other reflective and/or diffusely reflective displays.
  • the display panel can also include other components such as absorbing or reflecting polarizers, retarder films, diffusers, reflectors, beam splitters, brightness enhancement films, lenses or lens arrays, antireflective coatings, or other such light management films, coatings, and optical components as desired.
  • Added light management films, coatings, and optical components can be positioned behind the object to be illuminated, between the object to be illuminated and the light guide, or in front of the light guide.
  • Light source 22 can be any light source suitable for optical coupling with light input surfaces located on one or more edges of the light guide.
  • Exemplary light sources include cold-cathode fluorescent tubes, one or more light emitting diodes, large core optical fibers, preferably with light extraction systems or structures, or other light extracting conduits that pipe light from one or more internal or external light sources, and other suitable light sources.
  • Exemplary light sources also include one or more point light sources coupled to a linear light guide such as disclosed in U.S. Pat. Nos. 5,894,539 and 5,506,929.
  • the light source is optically coupled to the light guide such that a substantial proportion of the light emitted by the light source is injected into the light guide.
  • the light guides 10 and 10' shown in FIGs. 1 and 2, respectively, are shown to have a single light source, it is contemplated that light guides of the present invention can include more than one light source coupled to one or more light input surfaces on one or more edges of the light guide.
  • the present invention includes front light guides that have extractors extending toward the display panel that have dimensions and characteristics selected to improve various display performance factors.
  • Rough surfaces can cause scattering at surfaces.
  • a diffuse scattering event at a rough surface can cause light to be scattered equally in all directions.
  • Haze can be reduced with smoother surface finishes.
  • the smoothness of the surface finish typically depends greatly on the fabrication method. For example, when molding extractors, the surface finish of the mold or the tool is at least partially transferred to the surfaces of the extractors and the light guide (if the light guide is molded along with the extractors).
  • a preferred method of making optically smooth tools and molds is by diamond turning.
  • diamond turning As disclosed in the article E. Ray McClure, "Manufacturers Turn Precision Optics with Diamond,” Laser Focus World. (February, 1991) (McClure article), diamond turning has the capability of producing surfaces with root mean square (RMS) roughnesses of less than 1 nm.
  • RMS root mean square
  • a surface finish less than 20 nm RMS roughness is generally preferred, and 10 nm RMS roughness is more preferred.
  • light guides and extractors that have relatively rough surfaces might be desirable depending on the application.
  • Another factor that can affect display performance is the radius of curvature of the co er between the side walls of the extractors and the back surface of the light guide.
  • the radius of curvature of the comer is small compared to the height or width of the extractors, then there is a higher areal density of extractor side surfaces from which light can be extracted toward the display panel than there is areal density of curved comers from which light can be reflected toward the observer.
  • the radius of curvature of the extractor corners is less than about 5% the height of the extractors, more preferably less than about 3%, and even more preferably less than about 1%.
  • diamond turning has the capability of producing comers with radii of curvature on the order of tens of nanometers. This is sufficient to make sharp comers for extractors having heights measured in micrometers.
  • extractor spacing Another factor that can affect display performance is extractor spacing. Closely- spaced extractors generally increase the extraction efficiency due to an increased density of extractors. However, extractors that are too closely spaced might not leave room enough between adjacent extractors for extracted light to "clear" an adjacent extractor and reach the display panel. The effects of extractor spacing on contrast modulation, extraction efficiency, and extraction ratio are discussed in more detail hereinafter.
  • the spacing between extractors can be uniform or be varied across the light guide. For example, extractors can be spaced according to a variable pitch resulting in an extractor density that increases with increasing distance from an edge of the light guide where a light source is mounted. Varying extractor spacing can increase the uniformity of light extraction across the light guide, especially for larger displays. For smaller displays (on the order of 10 cm or less), uniform light extraction might be achieved without extractor density variations.
  • the aspect ratio of an extractor is best defined as the height of the extractor (measured from the back surface of the light guide to the termination surface of the extractor) divided by the effective width of the extractor in the main direction of light propagation (measured at the base of the extractor adjacent the back surface of the light guide). The lower the aspect ratio, the shorter the extractor compared to its width. Because the effective width of an extractor can vary depending on extractor shape and orientation and on the direction of light propagation, the aspect ratio that a particular ray of light "sees" when it encounters an extractor can likewise vary.
  • the orientation of the extractors with respect to the main direction of light propagation can be a factor in display performance.
  • each extractor is completely symmetric in the plane of the light guide.
  • the orientation of the extractors with respect to the net direction of light propagation can affect light extraction. This is due to at least two primary mechanisms.
  • the angle of the extractor side surfaces with respect to the light propagation depends on the orientation of the extractors.
  • This angle generally affects the overall direction of light extraction toward the display panel.
  • the performance of a front light guide may be measured in terms of various performance factors.
  • One such performance factor is light extraction efficiency, which measures the amount of light extracted from the light guide toward the viewable surface of the display panel as a fraction of the amount of light injected into the light guide.
  • Another performance factor is contrast modulation, which measures the ability of a viewer to discern between lighter and darker areas of the display.
  • a related performance factor is the angular dependence of the contrast modulation. Less sensitive angular dependence of contrast modulation with viewing angle results in display contrast that remains more uniform as the display is tilted relative to the viewer. Additionally, the contrast modulation preferably remains relatively high over a wide range of angles.
  • extraction ratio Another performance factor is the extraction ratio, which measures the percentage of light extracted from the light guide toward the viewer without illuminating the display versus the light extracted from the light guide toward the display panel.
  • Low extraction ratios lead to degraded display appearance, usually from a loss of display contrast and an overall hazy appearance.
  • Extraction ratio and contrast modulation are closely related in that both performance factors measure the amount of contrast observable in a front lit display. The actual contrast will, of course, also be affected by the properties of the surface (or object) to be illuminated.
  • the performance factors indicated above namely contrast modulation, angular dependence of contrast modulation, extraction efficiency, and extraction ratio, can be affected by various physical characteristics of the extractors on the front light guide.
  • front light guide performance can be correspondingly enhanced.
  • Physical characteristics of the front light guide and extractors that can contribute to performance include: the index of refraction of the front light guide and of the extractors; the spacing between adjacent extractors; the aspect ratio of the extractors; the overall shapes of the extractors; the orientation of the extractors relative to the main direction of light propagation through the light guide; the side wall angle of the extractors; and the surface finish of the extractors and the light guide.
  • the present invention provides a front light guide that includes extractors that have spacings, aspect ratios, shapes, orientations, sizes, and wall angles selected to enhance the performance of the front light guide in a front lit display assembly. Accordingly, the various characteristics that contribute to front light guide performance can be individually or interdependently controlled and selected based on the light guide material, extractor material, preferred application of the front light guide, and other such concerns.
  • Contrast modulation provides a measure of how well a viewer can discern between light and dark (or blocked and unblocked) portions of a display. Contrast modulation can be defined by:
  • W is the amount of light that reaches a viewer apparently from a white area of the display (or from a pixel in a "non-blocking" or “on” state in the case of an LCD)
  • B is the amount of light that reaches a viewer apparently from a black area of the display (or from a pixel in a "blocking" or “off' state in the case of an LCD or other light valve).
  • the contrast modulation exhibited by a particular front light guide depends on the characteristics of the surface being illuminated. For example, light guides illuminating diffusely reflective surfaces can exhibit very different contrast modulation numbers than the same light guides illuminating specularly reflective surfaces.
  • a test for comparing contrast modulation performance of front light guides is to determine the contrast modulation exhibited by the light guides when illuminating an at least 90% diffusely reflective white surface and an at most 10% diffusely reflective black surface.
  • the diffusely reflective surfaces used for this test specularly reflect 10% or less of the total light reflected off the surfaces. Accordingly, when contrast modulation values are given in this document, the values refer to the contrast modulation values obtained when illuminating an at least 90% diffusely reflective white surface and an at most 10% diffusely reflective black surface. Contrast modulation can also vary depending on the viewing angle, with the viewing angle defined by the angle between the viewer and an axis perpendicular to the display panel. Enhanced display performance results when contrast modulation remains high over a relatively wide range of viewing angles.
  • a front light guide according to the present invention has extractors selected to improve contrast modulation over a selected range of viewing angles.
  • the front light guides of the present invention exhibit a contrast modulation that is relatively high (preferably at least about 0.5, more preferably at least about 0.7, and even more preferably at least about 0.8) and remains substantially uniform (15% or less variance) throughout a relatively large range of viewing angles (preferably up to about 30°, more preferably up to about 45°, and even more preferably up to about 60°).
  • the contrast modulation can be symmetric or asymmetric with respect to viewing angle. For example, the contrast modulation can remain high within a relatively large range of viewing angles along one axis while remaining high within a narrower range of viewing angles along another axis.
  • the center-to-center spacing and aspect ratio of extractors on front light guides can be selected according to the present invention to enhance contrast modulation over a range of viewing angles. Contrast modulation tends to increase as the spacing between adjacent extractors increases and as the aspect ratio of the extractors increases.
  • the average center-to-center spacing between adjacent extractors is preferably at least about 2 times the width of the extractors and more preferably at least about 3 times the width of the extractors. For extractor spacings less than about 2 times the width of the extractors, contrast modulation can decrease. Contrast modulation also tends to increase with increasing height-to-width aspect ratio of the extractors.
  • the aspect ratio of the extractors is preferably at least about 1, more preferably at least about 1.2, and even more preferably at least about 1.5.
  • Extraction Efficiency is the amount of light extracted from the light guide toward the display panel. Higher extraction efficiency corresponds to higher display panel illumination for the same amount of light input, and thus results in a brighter display.
  • the extraction efficiency increases due to a higher density of extractors on the light guide.
  • the extraction efficiency generally increases as the extractor aspect ratio increases due to the increase in extractor wall surface area.
  • the extraction efficiency decreases as extractor aspect ratios increase above about 1. The mechanism for this decrease in extraction efficiency is most likely re-entry of extracted light rays into adjacent extractors due to the close spacing of the extractors and the relatively large heights of the extractors.
  • extractor spacings become small and/or aspect ratios become very large, a significant amount of the light extracted from the extractor side surfaces re-enters the light guide at the side surfaces of neighboring extractors.
  • light guides according to the present invention preferably include extractors that have aspect ratios of about 1 to 2, more preferably about 1 to 1.5, and even more preferably about 1.2 to 1.5 where the center-to-center spacing between extractors is preferably at least about 2 times the width of the extractors, and more preferably at least about 3 times the width of the extractors.
  • the center-to-center spacing between extractors is preferably at least about 2 times the width of the extractors, and more preferably at least about 3 times the width of the extractors.
  • gains in contrast modulation tend to be counteracted by losses in extraction efficiency.
  • Some of the loss of extraction efficiency due to large spacings can be counteracted, for example, by placing mirrors at the edges of the light guide and/or forming the light guide into a wedge shape.
  • Wedge-shaped light guides can affect the angle of light output and can contribute to increased light escape through the front surface of the light guide.
  • Extraction ratio measures the amount of light extracted toward the display panel versus the amount of light that escapes toward the viewer and can be defined by:
  • Display + Viewer where Display is the amount of light extracted from the light guide toward the display (out the extractor side, or back side, of the light guide) and Viewer is the amount of light escaping from the light guide toward the viewer (out the front surface of the light guide). Extraction ratio is preferably maximized to reduce the appearance of haze in the display and to increase the contrast and clarity of the display.
  • light guides according to the present invention preferably have extractors with center-to-center spacings that are preferably at least about 2 times the width of the extractors, more preferably at least about 3 times the width of the extractors, and with aspect ratios that are preferably at least about 1, more preferably about 1.2 or greater, and even more preferably about 1.5 or greater.

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  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Planar Illumination Modules (AREA)

Abstract

L'invention concerne un ensemble d'affichage (100) comprenant un panneau d'affichage (20) possédant une surface visible, un guide optique (10) doté de plusieurs extracteurs (14) s'étendant jusqu'au panneau d'affichage (20), et une source de lumière (12) couplée au plan optique au guide optique (10), de manière que de la lumière soit injectée dans le guide optique (10). Les extracteurs (14) sur le guide optique (10) présentent un rapport de forme, des espacements, des formes et des orientations choisies, de manière que le guide optique présente une modulation de contraste d'au moins environ 0,5 pour une surface blanche à réflexion diffuse d'au moins 90 % et d'au plus 10 % pour une surface noire à réflexion diffuse, la modulation de contraste étant sensiblement homogène pour la visualisation d'angles pouvant atteindre 60°.
PCT/US1999/026078 1999-07-01 1999-11-05 Ensemble d'affichage dote d'un guide optique frontal WO2001002772A1 (fr)

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AU14682/00A AU1468200A (en) 1999-07-01 1999-11-05 Display assembly having a front light guide

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US34024799A 1999-07-01 1999-07-01
US09/340,247 1999-07-01

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WO2016156562A1 (fr) * 2015-04-02 2016-10-06 Philips Lighting Holding B.V. Système d'éclairage utilisant un guide de lumière et procédé d'éclairage
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WO2019072938A1 (fr) 2017-10-10 2019-04-18 Katholieke Universiteit Leuven Plaque-guide de lumière
US20190263023A1 (en) * 2018-02-26 2019-08-29 Carpe Diem Technologies, Inc. System and method for constructing a roller-type nanoimprint lithography (rnil) master
US10416377B2 (en) 2016-05-06 2019-09-17 Cree, Inc. Luminaire with controllable light emission
WO2020046386A1 (fr) * 2018-08-31 2020-03-05 Hewlett-Packard Development Company, L.P. Unités d'affichage
IT201900004217A1 (it) * 2019-03-22 2020-09-22 Pel Plastic S R L Pannello di finitura
US11719882B2 (en) 2016-05-06 2023-08-08 Ideal Industries Lighting Llc Waveguide-based light sources with dynamic beam shaping

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