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WO2019217365A1 - Microstructures optiques modifiées pour une extraction de lumière améliorée - Google Patents

Microstructures optiques modifiées pour une extraction de lumière améliorée Download PDF

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Publication number
WO2019217365A1
WO2019217365A1 PCT/US2019/031037 US2019031037W WO2019217365A1 WO 2019217365 A1 WO2019217365 A1 WO 2019217365A1 US 2019031037 W US2019031037 W US 2019031037W WO 2019217365 A1 WO2019217365 A1 WO 2019217365A1
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WIPO (PCT)
Prior art keywords
optical
transparent
planar surface
mol
edge
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PCT/US2019/031037
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English (en)
Inventor
Byung Yun Joo
Steven S Rosenblum
James Andrew West
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Corning Inc
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Corning Inc
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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
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133615—Edge-illuminating devices, i.e. illuminating from the side

Definitions

  • the present disclosure relates to backlighting for LCD panels.
  • Conventional backlight configurations comprise a flat glass lightguide plate (LGP) between 0.5 and 3 mm in thickness with a row of white light-emitting diodes (LEDs) along one or both long edges of the respective display or monitor.
  • LGP flat glass lightguide plate
  • LEDs white light-emitting diodes
  • Light is uniformly extracted from the display using a pattern various scattering or refractive light extraction features that are incorporated into the LGP using screen printing, inkjet printing, laser patterning, etching or various other processes.
  • This light extraction pattern is generally selected so that output light has a spatial luminance output that is typically peaked in the middle of the display and decreases to 60-90% of the peak luminance at the edges.
  • a back reflector (diffusive or specular) is typically placed behind the LGP and various optical films are placed between the LGP and the liquid-crystal module (LCM). These optical films consist of diffusers, brightness enhancement films (BEFs) and reflective polarizers (DBEFs).
  • BEFs brightness enhancement films
  • DBEFs reflective polarizers
  • the combination of reflector, LGP and optical films is known as the BLU.
  • the optical films and the back reflector form an optical cavity that recycles and scatters light that has the wrong polarization or angular direction. Eventually the light will escape from this optical cavity when it has the correct polarization and when its angular direction falls within a desired cone of angular emission.
  • Recent BLUs designs also include local-dimming functionality.
  • the LED light fans out at approximately ⁇ 42° from the input LED location, thereby lighting a significant portion of the width of the LGP.
  • optical microstructures having lenticular surfaces i.e., curved surfaces
  • Local dimming enables spatial control of contrast enhancement by modulating the intensity of individual LEDs or groups of LEDs. Local dimming also has the effect of increasing brightness by more efficiently extracting light from the LGP.
  • BLUs can employ blue LEDs and quantum dots (QD) to improve the color gamut of the TV.
  • QDs are encapsulated in a film placed within the BLU, above the LGP. After the blue light has been extracted from the LGP, recycling of the light within the optical cavity allows for repeated interactions of the blue light with the red and green QDs thereby enhancing wavelength conversion.
  • the BLU has many optical components. Typically, these are independent and stand-alone components, but there can be advantages in integrating some of these components into a BLU with fewer independent layers. The advantages include reduced cost, fewer SKUs (stock keeping units), improved reliability, improved optical performance, ease of assembly, and increased stiffness.
  • optical contact means that the adjacent surfaces of two optical elements are conformal and are in physical contact with no separation by intervening materials (such as air).
  • optical contact can be achieved by using a liquid or film adhesive or resin as one of the layers. This class of material will wet the surface of the second element forming a complete physical contact. If the material is a liquid- based resin, it will be cured to a solid state by optical and/or thermal curing. This is the lamination that is described in the following paragraph
  • an approach to such integration involves laminating the optical components as optical films to the LGP.
  • laminating optical films to the LGP while providing the integration advantages mentioned above, results in some undesirable effects.
  • the LGPs rely on total internal reflection at the air interfaces on the top and bottom main surfaces of the LGPs. But, because most optical materials have refractive indices near 1.5 across the visible wavelength range, which is similar to the refractive index of the typical glass or plastic materials used in LGPs, if such materials are used in lamination, the light in the LGPs quickly escape into these added layers and light extraction can no longer be controlled to deliver uniform luminance in the BLU.
  • a manifestation of this problem in conventional displays and monitors is a bright band of light near the LED input edge.
  • Advantages of exemplary embodiments include an improvement to LCD performance by eliminating image degradation caused by the presence of the bright band and production of a brighter image by increasing the overall luminance of the display. Further advantages of exemplary embodiments eliminate the need for a large bezel to cover the bright band.
  • Some embodiments of the present disclosure relate to an optical assembly comprising a transparent LGP, a low-index optical layer, and an optical lenticular layer.
  • the optical lenticular layer includes an array of elongated lenticular lens structures whose cross-sections are trapezoidal or substantially rectangular with a side-wall angle approaching 90°.
  • the elongated lenticular lens structures comprise a height that tapers to zero as they near the light input edge of the LGP.
  • the optical lenticular layer can be offset near the light input edge of the LGP so the lenticular lens structures do not exist within the offset distance along the light input edge of the LGP.
  • the lenticular structures can comprise a fixed height over their elongated length without tapering, thus having a rectangular profile over their length. The rectangular profile lenticular structures can also be offset from the light input edge of the LGP.
  • FIG. 1 A is a cross-sectional view of an exemplary display device comprising a BLU.
  • FIG. 1B is an illustration of an exemplary FGP showing some of the basic structures.
  • FIG. 2A is an illustration of the exemplary FGP viewed from the light input surface of the FGP showing the azimuthal angle f notation for the input light rays in the FGP system.
  • FIG. 2B is an illustration of the exemplary FGP system of FIG. 2 A viewed from the side showing the relationship between the light input cone angle 0air and
  • FIG. 3 is an illustration of the exemplary FGP system of FIGS. 2A and 2B viewed from an oblique angle showing the azimuthal angle ()>LGP and the light cone angle 0air for the input light rays in the FGP system.
  • the dashed line illustrates the limiting angle of the rays of light from a Lambertian LED coupled into the input surface.
  • the angles above the dashed line and below the solid line represent light leakage due to the loss of total internal reflection.
  • the new angle will depend on the azimuthal angle around the input cone.
  • no angles 0’LGP drop below the critical angle of the air/glass interface (shaded region ⁇ 42°) where the ray will no longer be subject to total internal reflection and some light will be lost.
  • the extreme high -angle rays from the light source i.e. 0LGP ⁇ 42°
  • FIG. 7 is a depiction of some exemplary prism lenticular features.
  • FIG. 8 is a graphical illustration of a comparison of modeled bright band illuminance versus prism side-wall angle, A.
  • FIG. 9 is a plot of the normalized illuminance of the bright band near the FEDs as a function of the position along the FGP away from the light input surface.
  • FIG. 10 is a depiction of the definition of local dimming index (EDI).
  • EDI is local dimming index defined in S. Jung, M. Kim, D. Kim, J. Fee, "Focal dimming design and optimization for edge-type FED backlight unit,” SID Symp. Dig. Tech. Papers (2011) pp. 1430- 1432.
  • FIG. 1 1 is a depiction of positive relief and negative relief lenticular arrays showing tapering.
  • FIG. 12A shows a cross-sectional view of the mathematical taper function g(z) for an embodiment of the tapered lenticular structure of the present disclosure.
  • FIG. 12B shows a cross-sectional view of the mathematical taper function g(z) for another embodiment of the tapered lenticular structure of the present disclosure.
  • FIG. 12C shows a cross-sectional view of the mathematical taper function g(z) for another embodiment of the tapered lenticular structure of the present disclosure.
  • FIG. 13A shows a cross-sectional view of circular lenticular structures according to some embodiments viewed from the light input surface of the LGP.
  • FIG. 13B shows a cross-sectional view of triangular lenticular structures according to some embodiments viewed from the light input surface of the LGP.
  • FIG. 13C shows a cross-sectional view of trapezoidal lenticular structures with angle A ⁇ 90° according to some embodiments viewed from the light input surface of the LGP.
  • Ranges can be expressed herein as from“about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment 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 embodiment. 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.
  • Some embodiments include a display having an edge-lit LCD BLU with an LGP. Light from an array of LEDs is coupled into the bottom edge of the transparent LGP and then this light is extracted from the LGP at a uniform rate as it is guided towards the top of the LGP.
  • LGP For the LGP to function correctly it should be highly transparent to minimize light absorption, have smooth edges and sufficient thickness to enable efficient coupling of the light from the LED array, enable total internal reflection (TIR) at all of the non-extraction surface locations in order to maintain light guiding, and have a variable light extraction pattern on the back surface that can extract light at an approximately uniform rate.
  • some embodiments are directed to an optical assembly which is an LCD display device 10 comprising an LCD display panel 12 and a BLU 24 arranged to illuminate the LCD panel 12 from behind, i.e., from the backplane side of the LCD panel, using an array of LED light source 50 positioned along one edge of the BLU 24.
  • the LCD display panel 12 comprises a first substance 14 and a second substrate 16 joined by an adhesive material 18 positioned between and around a peripheral edge portion of the first and second substrates.
  • the first and second substrates 14, 16 and adhesive material 18 form a gap 20 therebetween containing liquid crystal material. Spacers (not shown) may also be used at various locations within the gap to maintain consistent spacing of the gap.
  • the first substrate 14 may include color filter material.
  • second substrate 16 includes thin film transistors (TFTs) for controlling the polarization state of the liquid crystal material, and may be referred to as the backplane.
  • LCD panel 12 further includes two polarizing filters 22 disposed on opposite sides of the gap 20 containing the liquid crystal material.
  • the BLU 24 may be spaced apart from the LCD panel 12, although in further embodiments, the BLU may be in contact with or coupled to the LCD panel, such as with a transparent adhesive. Additional optical films (not shown in FIG. 1 A) such as diffusers, BEFs, and DBEFs are commonly placed between the LCD panel 12 and the BLU 24.
  • BLU 24 comprises a glass light guide plate LGP 26 formed with a glass sheet 28 as the light guide, glass sheet 28 including a first major surface 30, a second major surface 32, and a plurality of edge surfaces extending between the first and second major surfaces.
  • glass sheet 28 may be a parallelogram, for example a square or a rectangle comprising four edge surfaces 34a, 34b, 34c, and 34d as shown in FIGS. 1 A and 1B extending between the first and second major surfaces defining an X-Y plane of the glass sheet 28, as shown by the X-Y-Z coordinates.
  • edge surface 34a may be opposite edge surface 34c
  • edge surface 34b may be positioned opposite edge surface 34d.
  • Edge surface 34a may be parallel with opposing edge surface 34c
  • edge surface 34b may be parallel with opposing edge surface 34d.
  • Edge surfaces 34a and 34c may be orthogonal to edge surfaces 34b and 34d.
  • the edge surfaces 34a-34d may be planar and orthogonal to, or substantially orthogonal (e.g., 90 +/- 1 degree, for example 90 +/- 0.1 degree) to major surfaces 30, 32, although in further embodiments, the edge surfaces may include chamfers, for example a planar center portion orthogonal to, or substantially orthogonal to major surfaces 30, 32 and joined to the first and second major surfaces by two adjacent angled surface portions.
  • the BLU 24 comprises the transparent substrate 28 having an index of refraction n0>l, the transparent substrate 28 having a thickness tO separating an upper planar surface 30 and a lower planar surface 32 parallel to the upper planar surface.
  • the transparent substrate 28 comprises an optical input surface 34a perpendicular to the upper and lower planar surfaces.
  • the transparent substrate 28 also comprises an optical output surface 34c parallel to the optical input surface 34a.
  • the optical assembly also comprises a first transparent coating layer 36 having an index of refraction nl where l ⁇ nl ⁇ n0, and has a thickness tl separating an upper planar surface and a lower planar surface of the first transparent coating layer 36.
  • the upper planar surface of the first transparent coating layer 36 is in optical contact with the lower planar surface of the transparent substrate 28.
  • the optical assembly further comprises a second transparent layer 40 having an index of refraction n2 where
  • the lower planar surface of the second transparent layer 40 is in optical contact with the upper planar surface of the transparent substrate 28.
  • L2 and z2 are chosen to minimize the variance in output intensity and color from the optical assembly.
  • an array of elongated optical structures 42 also referred to as lenticular structures, (see FIG. 1B) are disposed on the upper surface of the second transparent layer 40.
  • the array of the lenticular structures 42 have an index of refraction n3 substantially equal to index of refraction n2.
  • the lenticular structures 42 are disposed in an array of substantially parallel rows where the elongation direction is in an alignment direction along the axis z.
  • the array of lenticular structures 42 are substantially periodic, in the direction x that is perpendicular to the axis z, with a period of P (see FIG. 13C, for example).
  • the first edge at z3 represents where the lenticular structures 42 begins near the light input surface 34a.
  • L3 and z3 are chosen to minimize the variance in output intensity and color from the optical assembly. z3 > z2 and in some
  • z3 z2.
  • the lenticular structures 42 can start at the first edge of the second transparent layer 40 or offset some distance from the first edge of the second transparent layer 40.
  • the individual lenticular structure 42 preferably comprises a trapezoidal cross-sectional shape with a side-wall angle A, where 80° ⁇ A ⁇ 90°, a width W along a direction x perpendicular to the axis z and parallel to the plane of the lower surface of the second transparent layer 40.
  • the width W is ⁇ P
  • the lenticular structures 42 have a constant height H3 in a direction y perpendicular to the plane of the upper and lower surfaces of the second transparent layer 40 (i.e., perpendicular to both the z axis and x axis).
  • z3>0 which means that the lenticular structures 42 are offset from the edge of the optical input surface 34a of the LGP.
  • the choice of LI, L2, L3, and zl, z2, z3 depend on the details of the illumination source incident on the light input surface 34a, bezel thickness, and any optical reflectors on surfaces 34b, 34c, or 34d.
  • the width W of the individual lenticular structure 42 is ⁇ P and the individual lenticular structures 42 comprise a height H3 that can vary along a direction parallel to axis z.
  • L3’ can be ⁇ L3
  • the height H3 can start from no height. In some other embodiments, the height H3 can start from a fixed value as a step. In some embodiments, the tapering profile over the length L3’ is such that the height H3 reaches the maximum value H3max by increasing monotonically over the length L3’, meaning that it will not decrease at any point over the length L3’. In some embodiments, the height H3 reaches the maximum value H3max by increasing with a constant slope over the length L3’, i.e., in a straight line as shown in FIG. 12A.
  • the tapering profile over the length L3’ can be determined according to a mathematical taper function g(z).
  • FIGS. 12A-12C show examples of mathematical taper functions g(z).
  • the taper function g(z) should be continuous and monotonically increasing but it need not be smooth in its derivative dg(z)/dz.
  • width W is substantially equal to the period P.
  • Some embodiments include a ratio 0.l ⁇ W/P ⁇ l .
  • Some embodiments include a slope of the mathematical function being monotonically increasing and continuous as show in FIGS. 12A-12C.
  • the elongated lenticular structures have a circular or elliptical segment, a triangular, a trapezoidal, or a rectangular cross-sectional profile when sectioned along the direction x, as show in FIGS. 13A-13D, respectively.
  • Some embodiments include a glass transparent substrate.
  • TIR at all of the non-extraction surface locations is required to maintain light guiding.
  • the angular output of the light from LEDs is substantially described as a Lambertian distribution which according to Lambert’s law means that the radiant intensity observed from the LED is directly proportional to the cosine of the angle Q between the direction of the incident light and the surface normal of the LED. This means that the LED emits light into the entire half sphere away from its emission surface.
  • FIG. 1B is an illustration of an exemplary LGP 28 showing the basic structures.
  • An LGP 28 with a first transparent coating layer 36, a low refractive index layer, is deposed on a bottom surface and a second transparent layer, an array of lenticular structures 40 disposed on a top surface.
  • FIG. 2A is an illustration of the exemplary LGP viewed from the light input surface of the LGP showing the azimuthal angle f notation for the input light rays in the LGP system.
  • FIG. 2B is an illustration of the exemplary LGP system of FIG. 2A viewed from the side showing the relationship between the light input cone angle 0air and
  • FIG. 2C is an illustration of the exemplary LGP system of FIIGs. 2A and 2B viewed from an oblique angle showing the azimuthal angle f and the input light cone angle 0 air for the input light rays in an input light cone in the context of the LGP system.
  • FIG. 3 is an illustration of the exemplary LGP system of FIIGs. 2A and 2B viewed from an oblique angle showing the azimuthal angle f and the light cone angle 0 air for the input light rays in the LGP system.
  • the dashed line illustrates the limiting angle of the rays of light from a Lambertian LED coupled into the input surface.
  • the angles above the dashed line and below the solid line represent light leakage due to the loss of total internal reflection.
  • the new angle after each reflection will depend on the azimuthal angle ()>LGP around the input cone.
  • no angles 0’LGP drop below the critical angle of the air/glass interface (shaded region ⁇ 42°) where the ray will no longer be subject to total internal reflection and some light will be lost.
  • the extreme high-angle rays from the light source i.e. 0LGP ⁇ 42°
  • ⁇ 4l .8° we find that
  • the light rays remain on the input cone defined by their angle 0LGP with respect to the input normal. Moreover, the light rays maintain their azimuthal angle ()>LGP around the input cone, except for a symmetric flip each time they reflect on one of the planar sides.
  • Some embodiments provide a solution to problems that are encountered when the design of the BLU comprises two conditions where two of our basic assumptions for an ideal LGP are simultaneously broken, the two conditions being: (1) that at least one of the non-input faces of the LGP is no longer an air/LGP interface because a coating material other than air is present, and (2) at least one of the non-input faces of the LGP (not necessarily the same interface) is non-planar.
  • the low-index region scatters or absorbs the light, or the low-index layer is in optical contact with another scattering (for example, the back reflector of the BLU) or absorbing material, light will be lost from the LGP.
  • another scattering for example, the back reflector of the BLU
  • All currently available optical coating materials have scattering and absorption that are greater than that of the commonly used glass and polymer LGP materials.
  • the impact of the second broken assumption occurs when lenticulars or other non- planar optical features are placed on one of the non-input faces.
  • the lenticulars are aligned perpendicular to the input face and may contain light extraction features. If all of the interfaces are air/glass, there is no extraction of light by the smooth lenticulars. However, these non-planar interfaces cause the internal ray angles to be constantly redirected. The rays will remain on the same input cone (i.e., GLGP will stay constant), but their azimuthal angle about the input cone will be constantly changing as they encounter the curved lenticular surfaces. Although individual rays are being redirected, the average angular distribution of rays within the LGP will remain unchanged and will be indistinguishable from the non-lenticular case.
  • This mixing time determines the width of the excess bright band along the z axis, so the ideal lenticulars either mix the light quickly to produce a narrow but intense bright band, or the lenticulars do not mix the light at all and produce a much weaker and narrow bright band.
  • Preferred lenticulars should be those with substantially vertical side walls and flat tops. This should behave identically to the planar LPG and have the expect light extraction due to the failure of TIR as shown in FIG. 6. Deviations from vertical side walls can be tolerated and the side-wall angle A is preferably >80°. In some embodiments, the side-wall angle A is 80°. In some embodiments, the side-wall angle A is 85°. In some embodiments, the side- wall angle A is preferably 87°. In some embodiments, the side-wall angle A is more preferably 89°. Some corner rounding can be tolerated.
  • FIG. 7 shows a schematic illustration of a cross-section of an exemplary prism lenticular feature.
  • A is the side- wall angle of the prismatic lenticular structure
  • P is the period of the prism lenticular features
  • W is the width of the prism structures
  • H3 is the height of the prism structures.
  • a prism side-wall angle A of 0° represents a flat LGP without any lenticular structures.
  • FIG. 9 is a graphical illustration of modeled luminance of the bright bands seen near the LED light sources.
  • the X-axis represents the distance (in mm) from the optical input surface 34a (i.e., near the LEDs) and the Y-axis representing the normalized illuminance.
  • a luminance curve for a theoretically ideal case where there is a uniform illuminance throughout the LGP without any bright band effect would be a straight line representing a constant illuminance over the distance.
  • conventional lenticular structures 42 are provided on the top surface of the LGP 28 to enhance light extraction, however, undesired bright bands near the optical input surface 34a is observed.
  • This bright band effect is illustrated by the dashed line plot in FIG. 9 which is the illuminance for the standard circular cross-section lenticular structure case.
  • the peak illuminance is very nearly the same for all four cases but the width of the bright band is very different.
  • the circular lenticular case exhibits a wide bright band, which is not desired.
  • the A 90° prism lenticular structure, however, exhibits a very narrow bright band similar to the no lenticular (i.e. flat LGP) reference case.
  • the A 80° prism lenticular structure also exhibit similarly narrow bright band.
  • the Y-axis in the plot in FIG. 8 is the integrated signal under the curves in FIG. 9.
  • the two lowest points in FIG. 8 represent the no lenticular case 0° side-wall angle and 90° side-wall angle prism lenticular structure.
  • modifying the elongated lenticular structures by shaping them to have a prismatic cross-sectional shape having a straight side-wall with a side-wall angle A that is 90° or close to 90°, such as > 80° will reduce the bright band effect. Examples of such prismatic lenticular structures are illustrated in FIGS. 7, 13B, 13C, and 13D.
  • the improved lenticular structures of the present disclosure will not affect the local dimming functionality provided by the conventional lenticular structures already known by those skilled in the BLU art.
  • the local dimming effects can be measured in local dimming index (LDI) defined in S. Jung, M. Kim, I). Kim, J. Lee, "Local dimming design and optimization for edge- type LED backlight unit,” SID Symp. Dig. Tech. Papers (2011) pp. 1430-1432.
  • FIG. 10 is a graphical illustration of LDI.
  • FIG. 1 1 shows generic schematic illustrations of two types of tapered lenticular structures that are within the scope of the present disclosure.
  • “Type A: Flat-positive lenti” illustrates an array of protruding lenticular lens structure whose variable height tapers to 0 at or near the light input surface 34a of the LGP.
  • “Type B: Flat-Negative lenti” illustrates what is essentially a negative relief of the lenticular structure“Type A: Flat-positive lenti.”
  • the illustrations in FIG. 11 show the lenticular structures as having circular cross-sectional shape but those are just simplified generic illustrations.
  • the lenticular structure according to the present disclosure have a cross-section like the one exemplified in FIG.
  • Some embodiments described and depicted herein comprise lenticular features that have smooth or angular cross sections. Some embodiments include a lenticular array having flat sections between individual lenticular optical elements. Some embodiments include a lenticular array that can be offset from the edge of the LGP. Some embodiments include a lenticular array having integrated light extraction features. The dimensions (height, width and cross-sectional shape) of the lenticular array elements can vary along the length of the lenticular element in some embodiments. Asymmetry in the lenticular shape in some embodiments can increase the excess bright band by causing more mixing; however, exemplary embodiments reduce the total flux extracted into the bright band and reduce the width of the bright band.
  • Exemplary glass compositions in a LGP comprise between about 65.79 mol % to about 78.17 mol% SiCh, between about 2.94 mol% to about 12.12 mol% AI2O3, between about 0 mol% to about 11.16 mol% B2O3, between about 0 mol% to about 2.06 mol% LEO, between about 3.52 mol% to about 13.25 mol% Na 2 0, between about 0 mol% to about 4.83 mol% K2O, between about 0 mol% to about 3.01 mol% ZnO, between about 0 mol% to about 8.72 mol% MgO, between about 0 mol% to about 4.24 mol% CaO, between about 0 mol% to about 6.17 mol% SrO, between about 0 mol% to about 4.3 mol% BaO, and between about 0.07 mol% to about 0.11 mol% SnCh.
  • exemplary glass compositions comprise between about 66 mol % to about 78 mol% S1O2, between about 4 mol% to about 11 mol% AI2O3, between about 4 mol% to about 11 mol% B2O3, between about 0 mol% to about 2 mol% LEO, between about 4 mol% to about 12 mol% Na 2 0, between about 0 mol% to about 2 mol% K2O, between about 0 mol% to about 2 mol% ZnO, between about 0 mol% to about 5 mol% MgO, between about 0 mol% to about 2 mol% CaO, between about 0 mol% to about 5 mol% SrO, between about 0 mol% to about 2 mol% BaO, and between about 0 mol% to about 2 mol% Sn0 2 .
  • a respective glass article comprises a color shift ⁇ 0.008 or ⁇ 0.005.
  • Color shift as described herein can be characterized by measuring the variation in y chromaticity coordinate of the extracted light along a length L using the CIE 1931 standard for color measurements.
  • where Lf and Li are the positions along the z axis of the panel or substrate direction away from the light source launch at the optical input surface 34a and where Lf-Li 0.5 meters.
  • Exemplary light- guide plates have Dy ⁇ 0.01, and preferably Dy ⁇ 0.005, Dy ⁇ 0.003, or Dy ⁇ 0.001.
  • exemplary glass compositions comprise between about 72 mol % to about 80 mol% SiCh, between about 3 mol% to about 7 mol% AI2O3, between about 0 mol% to about 2 mol% B2O3, between about 0 mol% to about 2 mol% LEO, between about 6 mol% to about 15 mol% Na 2 0, between about 0 mol% to about 2 mol% K2O, between about 0 mol% to about 2 mol% ZnO, between about 2 mol% to about 10 mol% MgO, between about 0 mol% to about 2 mol% CaO, between about 0 mol% to about 2 mol% SrO, between about 0 mol% to about 2 mol% BaO, and between about 0 mol% to about 2 mol% Sn0 2 .
  • exemplary glass compositions comprise between about 60 mol % to about 80 mol% S1O2, between about 0 mol% to about 15 mol% AI2O3, between about 0 mol% to about 15 mol% B2O3, and about 2 mol% to about 50 mol% R x O, wherein R is any one or more of Li, Na, K, Rb, Cs and x is 2, or Zn, Mg, Ca, Sr or Ba and x is 1 , and wherein Le + 30Cr + 35Ni ⁇ about 60 ppm.
  • exemplary glass compositions comprise between about 0 mol% to about 15 mol% AI2O3, between about 0 mol% to about 15 mol% B2O3, and about 2 mol% to about 50 mol% R x O, wherein R is any one or more of Li, Na, K, Rb, Cs and x is 2, or Zn, Mg, Ca, Sr or Ba and x is 1, and wherein the glass has a color shift ⁇ 0.008.
  • exemplary glass compositions comprise between about 65.79 mol % to about 78.17 mol% S1O2, between about 2.94 mol% to about 12.12 mol% AI2O3, between about 0 mol% to about 11.16 mol% B2O3, and about 3.52 mol% to about 42.39 mol% R x O, wherein R is any one or more of Li, Na, K, Rb, Cs and x is 2, or Zn, Mg, Ca, Sr or Ba and x is 1, and wherein the glass has a color shift ⁇ 0.008.
  • exemplary glass compositions comprise between about 60 mol % to about 81 mol% S1O2, between about 0 mol% to about 2 mol% AI2O3, between about 0 mol% to about 15 mol% MgO, between about 0 mol% to about 2 mol% LEO, between about 9 mol% to about 15 mol% Na 2 0, between about 0 mol% to about 1.5 mol% K2O, between about 7 mol% to about 14 mol% CaO, between about 0 mol% to about 2 mol% SrO, and wherein Le + 30Cr + 35Ni ⁇ about 60 ppm.
  • exemplary glass compositions comprise between about 60 mol % to about 81 mol% S1O2, between about 0 mol% to about 2 mol% AI2O3, between about 0 mol% to about 15 mol% MgO, between about 0 mol% to about 2 mol% Li 2 0, between about 9 mol% to about 15 mol% Na 2 0, between about 0 mol% to about 1.5 mol% K 2 0, between about 7 mol% to about 14 mol% CaO, and between about 0 mol% to about 2 mol% SrO, wherein the glass has a color shift ⁇ 0.008.
  • a respective glass article comprises a color shift ⁇ 0.008 or ⁇ 0.005.
  • the glass comprises an R x 0/Al 2 0 3 between 0.95 and 3.23, wherein R is any one or more of Li, Na, K, Rb, Cs and x is 2.
  • the glass comprises an R x 0/Al 2 0 3 between 1.18 and 5.68, wherein R is any one or more of Li, Na, K, Rb, Cs and x is 2, or Zn, Mg, Ca, Sr or Ba and x is 1.
  • the glass article comprises an R x O - Al 2 C> 3 - MgO between -4.25 and 4.0, wherein R is any one or more of Li, Na, K, Rb, Cs and x is 2.
  • the glass comprises less than 1 ppm each of Co, Ni, and Cr.
  • the concentration of Fe is ⁇ about 50 ppm, ⁇ about 20 ppm, or ⁇ about 10 ppm.
  • the transmittance at 450 nm with at least 500 mm in length is greater than or equal to 85%
  • the transmittance at 550 nm with at least 500 mm in length is greater than or equal to 90%
  • the transmittance at 630 nm with at least 500 mm in length is greater than or equal to 85%, and combinations thereof.
  • the glass sheet is chemically strengthened.
  • the glass comprises from about 0.1 mol % to about 3.0 mol % ZnO, from about 0.1 mol % to about 1.0 mol % Ti0 2, from about 0.1 mol % to about 1.0 mol % V 2 0 3, from about 0.1 mol % to about 1.0 mol % Nb 2 Os , from about 0.1 mol % to about 1.0 mol % MnO, from about 0.1 mol % to about 1.0 mol % Zr0 2, from about 0.1 mol % to about 1.0 mol % As 2 C> 3 , from about 0.1 mol % to about 1.0 mol % Sn0 2 , from about 0.1 mol % to about 1.0 mol % M0O3, from about 0.1 mol % to about 1.0 mol % Sb 2 C> 3 , or from about 0.1 mol % to about 1.0 mol % Ce0 2 .
  • the glass comprises between 0.1 mol% to no more than about 3.0 mol% of one or combination of any of ZnO, Ti0 2 , V 2 0 3 , Nb 2 0 5 , MnO, Zr0 2 , As 2 03, Sn0 2 , M0O3, Sb 2 03, and Ce0 2
  • exemplary glass compositions comprise between about 50-80 mol% Si0 2 , between 0-20 mol% Al 2 0 3, and between 0-25 mol% B 2 0 3 , and less than 50 ppm iron (Fe) concentration.
  • exemplary glass compositions comprise between about 70 mol % to about 85 mol% Si0 2 , between about 0 mol% to about 5 mol% AhCb, between about 0 mol% to about 5 mol% B2O3, between about 0 mol% to about 10 mol% Na 2 0, between about 0 mol% to about 12 mol% K 2 0, between about 0 mol% to about 4 mol% ZnO, between about 3 mol% to about 12 mol% MgO, between about 0 mol% to about 5 mol% CaO, between about 0 mol% to about 3 mol% SrO, between about 0 mol% to about 3 mol% BaO, and between about 0.01 mol% to about 0.5 mol% Sn02.
  • exemplary glass compositions comprise between about 80 mol % S1O2, between about 0 mol% to about 0.5 mol% AI2O3, between about 0 mol% to about 0.5 mol% B2O3, between about 0 mol% to about 0.5 mol% Na 2 0, between about 8 mol% to about 11 mol% K2O, between about 0.01 mol% to about 4 mol% ZnO, between about 6 mol% to about 10 mol% MgO, between about 0 mol% to about 0.5 mol% CaO, between about 0 mol% to about 0.5 mol% SrO, between about 0 mol% to about 0.5 mol% BaO, and between about 0.01 mol% to about 0.11 mol% Sn0 2 .
  • exemplary glass compositions are substantially free of AI2O3 and B2O3 and comprises greater than about 80 mol % S1O2, between about 0 mol% to about 0.5 mol% Na 2 0, between about 8 mol% to about 11 mol% K2O, between about 0.01 mol% to about 4 mol% ZnO, between about 6 mol% to about 10 mol% MgO, and between about 0.01 mol% to about 0.11 mol% Sn0 2 .
  • the glass sheet is substantially free of B2O3, Na 2 0, CaO, SrO, or BaO, and combinations thereof.
  • exemplary glass compositions is an alumina free, potassium silicate composition comprising greater than about 80 mol % S1O2, between about 8 mol% to about 11 mol% K2O, between about 0.01 mol% to about 4 mol% ZnO, between about 6 mol% to about 10 mol% MgO, and between about 0.01 mol% to about 0.11 mol% Sn0 2 .
  • the glass sheet is substantially free of B2O3, Na 2 0, CaO, SrO, or BaO, and combinations thereof.
  • exemplary glass compositions comprise between about 72.82 mol % to about 82.03 mol% S1O2, between about 0 mol% to about 4.8 mol% AI2O3, between about 0 mol% to about 2.77 mol% B2O3, between about 0 mol% to about 9.28 mol% Na 2 0, between about 0.58 mol% to about 10.58 mol% K2O, between about 0 mol% to about 2.93 mol% ZnO, between about 3.1 mol% to about 10.58 mol% MgO, between about 0 mol% to about 4.82 mol% CaO, between about 0 mol% to about 1.59 mol% SrO, between about 0 mol% to about 3 mol% BaO, and between about 0.08 mol% to about 0.15 mol% Sn0 2 .
  • the glass sheet is substantially free of AI 2 O 3 , B 2 O 3 , Na 2 0, CaO, SrO, or BaO, and
  • exemplary glass compositions are substantially free of AI2O3 and B2O3 and comprises greater than about 80 mol % S1O2, and wherein the glass has a color shift ⁇ 0.005.
  • the glass sheet comprises between about 8 mol% to about 11 mol% K2O, between about 0.01 mol% to about 4 mol% ZnO, between about 6 mol% to about 10 mol% MgO, and between about 0.01 mol% to about 0.11 mol% SnC .
  • exemplary glass compositions are substantially free of AI2O3, B2O3, Na 2 0, CaO, SrO, and BaO, and wherein the glass has a color shift ⁇ 0.005.
  • the glass sheet comprises greater than about 80 mol % S1O2 .
  • the glass sheet comprises between about 8 mol% to about 11 mol% K2O, between about 0.01 mol% to about 4 mol% ZnO, between about 6 mol% to about 10 mol% MgO, and between about 0.01 mol% to about 0.11 mol% Sn0 2 .

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Planar Illumination Modules (AREA)

Abstract

L'invention concerne un ensemble optique comprenant une plaque de guidage de lumière transparente, une couche optique à faible indice et une couche lenticulaire optique, la couche lenticulaire optique comprenant un réseau de lentilles lenticulaires dont la section transversale est sensiblement rectangulaire avec un angle de paroi latérale s'approchant de 90°.
PCT/US2019/031037 2018-05-07 2019-05-07 Microstructures optiques modifiées pour une extraction de lumière améliorée Ceased WO2019217365A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070279551A1 (en) * 2006-05-30 2007-12-06 Hitachi Maxell, Ltd. Backlight unit and liquid crystal display apparatus
US7431491B2 (en) * 2006-03-25 2008-10-07 Hon Hai Precision Industry Co., Ltd. Light guide plate and backlight module using the same
US20080304282A1 (en) * 2007-06-11 2008-12-11 Xiang-Dong Mi Backlight containing formed birefringence reflective polarizer
US20130070480A1 (en) * 2010-03-26 2013-03-21 Iti Scotland Limited Encapsulated led array and edge light guide device comprising such an led array
US20130329452A1 (en) * 2012-06-12 2013-12-12 Skc Haas Display Films Co., Ltd. Method for reducing hot spots in light guide plates

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7431491B2 (en) * 2006-03-25 2008-10-07 Hon Hai Precision Industry Co., Ltd. Light guide plate and backlight module using the same
US20070279551A1 (en) * 2006-05-30 2007-12-06 Hitachi Maxell, Ltd. Backlight unit and liquid crystal display apparatus
US20080304282A1 (en) * 2007-06-11 2008-12-11 Xiang-Dong Mi Backlight containing formed birefringence reflective polarizer
US20130070480A1 (en) * 2010-03-26 2013-03-21 Iti Scotland Limited Encapsulated led array and edge light guide device comprising such an led array
US20130329452A1 (en) * 2012-06-12 2013-12-12 Skc Haas Display Films Co., Ltd. Method for reducing hot spots in light guide plates

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