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WO2008140176A1 - Feuille à prismes et lgp utilisant une structure prismatique polygonale, blu et lcd utilisant lesdites feuilles et lgp - Google Patents

Feuille à prismes et lgp utilisant une structure prismatique polygonale, blu et lcd utilisant lesdites feuilles et lgp Download PDF

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Publication number
WO2008140176A1
WO2008140176A1 PCT/KR2008/000972 KR2008000972W WO2008140176A1 WO 2008140176 A1 WO2008140176 A1 WO 2008140176A1 KR 2008000972 W KR2008000972 W KR 2008000972W WO 2008140176 A1 WO2008140176 A1 WO 2008140176A1
Authority
WO
WIPO (PCT)
Prior art keywords
prism
peak
guide plate
light guide
reversed
Prior art date
Application number
PCT/KR2008/000972
Other languages
English (en)
Inventor
Gyoung Tae No
Sun Mi Shin
Young Rim Lee
Original Assignee
Gyoung Tae No
Sun Mi Shin
Young Rim Lee
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
Priority claimed from KR1020070046050A external-priority patent/KR20080100017A/ko
Priority claimed from KR1020070082693A external-priority patent/KR20090018318A/ko
Application filed by Gyoung Tae No, Sun Mi Shin, Young Rim Lee filed Critical Gyoung Tae No
Publication of WO2008140176A1 publication Critical patent/WO2008140176A1/fr

Links

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
    • G02B6/0053—Prismatic sheet or layer; Brightness enhancement element, sheet or layer
    • 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
    • G02F1/133602—Direct backlight
    • G02F1/133611—Direct backlight including means for improving the brightness uniformity

Definitions

  • the present invention relates to the construction of an optical path modification means by using a polygonal prism structure. More particularly, the present invention relates to a prism sheet and a light guide plate having reversed prism peaks and prism peaks, respectively, based on a polygonal prism structure, as well as a backlight unit and an LCD using the same to improve both brightness and characteristics regarding the field of view.
  • Background Art
  • LCDs are light-receiving devices, i.e. they cannot emit light by themselves, unlike CRTs (Cathode Ray Tubes), and need a backlight device to maintain uniform brightness across the entire screen.
  • CRTs Cathode Ray Tubes
  • the backlight device includes a lamp 1 as a light source, a light guide plate 2 for scattering light incident from the lamp 1 to uniformize it; a reflection sheet 3 positioned below the light guide plate 2 to reflect light incident from the lamp 1 toward the top, on which a liquid crystal panel (not shown) is positioned, to prevent the light from leaking through the bottom of the light guide plate 2 and being lost; a diffusion sheet 4 positioned on a surface of the light guide plate 2 opposite the reflection sheet 3 to increase the uniformity of light; a prism sheet 5 arranged on top of the diffusion sheet 4; and a protection sheet 6 for stabilizing the color coordinate and protecting the prism structure of the prism sheet 5.
  • the prism sheet 5 is used to condense light diffused by the diffusion sheet 4 to obtain a predetermined level of brightness. As shown in FIG. 2, the prism sheet 5 has prism peaks 5a protruding upward from its upper surface to increase the efficiency of condensing light.
  • Such a conventional prism sheet 5 has a problem in that, although light diffused by the diffusion sheet 4 is vertically refracted and condensed toward the top so that the user can watch high-brightness images in front of the liquid crystal panel, the brightness substantially degrades as the field of view increases. In addition, the characteristics of the prism structure cause a loss of light because light is emitted from the lateral surface.
  • the fact that the optical propagation path is limited narrows the field of view, although the brightness may be increased by reflection.
  • the loss of light due to emission of light from the lateral surface persists.
  • the present invention has been made in view of the above-mentioned problems occurring in conventional prism sheets, as well as backlight units and displays using them, and the present invention provides a prism sheet having polygonal reversed prism peaks on its light incident surface based on a polygonal prism structure to improve both brightness and characteristics regarding the field of view.
  • the present invention also provides a backlight unit including a prism sheet having polygonal reversed prism peaks on its light incident surface based on a polygonal prism structure to improve both brightness and characteristics regarding the field of view.
  • the present invention also provides an LCD including a prism sheet having polygonal reversed prism peaks on its light incident surface based on a polygonal prism structure to improve both brightness and characteristics regarding the field of view.
  • the present invention also provides a light guide plate having polygonal prism peaks on its light emission surface based on a polygonal prism structure to improve both brightness and characteristics regarding the field of view.
  • the present invention also provides a backlight unit including a light guide plate having polygonal prism peaks on its light emission surface based on a polygonal prism structure to improve both brightness and characteristics regarding the field of view.
  • the present invention also provides an LCD including a light guide plate having polygonal prism peaks on its light emission surface based on a polygonal prism structure to improve both brightness and characteristics regarding the field of view.
  • the present invention also provides a prism sheet and a light guide plate having polygonal reversed prism peaks and polygonal prism peaks on the light incident surface and the light emission surface, respectively, based on a polygonal prism structure to improve both brightness and characteristics regarding the field of view, as well as a backlight unit and an LCD including the same.
  • a prism sheet for refracting light incident on a lower surface to concentrate the light toward an upper portion by using a polygonal prism structure, the prism sheet including a plurality of reversed prism peaks protruding from a reversed prism peak base region on the lower surface of the prism sheet, wherein each reversed prism peak is configured in a heptagonal cross section symmetric horizontally about a vertical line extending through an apex, and left and right sides of each reversed prism peak are bent to define first, second, and third regions of each reversed prism peak.
  • a prism sheet for refracting light incident on a lower surface to concentrate the light toward an upper portion by using a polygonal prism structure, the prism sheet including a plurality of reversed prism peaks protruding from a reversed prism peak base region on the lower surface of the prism sheet, wherein each reversed prism peak is configured in a heptagonal cross section asymmetric horizontally about a vertical line extending through an apex, and left and right sides of each reversed prism peak are bent to define first, second, and third regions of each reversed prism peak.
  • a backlight unit having a prism sheet using a polygonal prism structure, the backlight unit including a light guide plate for diffusing, reflecting, and refracting light rays from a light source to modify a propagation direction of the light rays so that the light rays are uniformly emitted toward an upper portion; a reflection sheet for reflecting light rays propagating vertically downward; a prism sheet positioned on top of the light guide plate, the prism sheet having reversed prism peaks protruding from a lower surface in a heptagonal cross section symmetric horizontally about a vertical line extending through an apex, left and right sides of each reversed prism peak being bent to define first, second, and third regions of each reversed prism peak; a diffusion sheet positioned on top of the prism sheet to increase uniformity of light; and a protection sheet for stabilizing color coordinates and protecting the sheets.
  • a liquid crystal display having a prism sheet using a polygonal prism structure
  • the liquid crystal display including a backlight unit including a light guide plate for diffusing, reflecting, and refracting light rays from a light source to modify a propagation direction of the light rays so that the light rays are uniformly emitted toward an upper portion, a reflection sheet for reflecting light rays propagating vertically downward, a prism sheet positioned on top of the light guide plate, the prism sheet having reversed prism peaks protruding from a lower surface in a heptagonal cross section symmetric horizontally about a vertical line extending through an apex, left and right sides of each reversed prism peak being bent to define first, second, and third regions of each reversed prism peak, a diffusion sheet positioned on top of the prism sheet to increase uniformity of light, and a protection sheet for stabilizing color coordinates and protecting the sheets; and a liquid crystal panel coupled
  • a light guide plate using a polygonal prism structure including a plurality of prism peaks positioned on an emission surface, wherein each prism peak has a heptagonal cross section symmetric horizontally about a vertical line extending through an apex, and left and right sides of each prism peak of the light guide plate are bent to define first, second, and third regions of each prism peak so that light rays from a light source are emitted toward an upper portion.
  • a light guide plate using a polygonal prism structure including a plurality of prism peaks positioned on an emission surface, wherein each prism peak has a heptagonal cross section asymmetric horizontally about a vertical line extending through an apex, and left and right sides of each prism peak of the light guide plate are bent to define first, second, and third regions of each prism peak so that light rays from a light source are emitted toward an upper portion.
  • a backlight unit having a light guide plate using a polygonal prism structure
  • the backlight unit including a light guide plate having a plurality of prism peaks on an emission surface, each prism peak having a heptagonal cross section symmetric horizontally about a vertical line extending through an apex, left and right sides of each prism peak of the light guide plate being bent to define first, second, and third regions of each prism peak; a reflection sheet positioned below the light guide plate to reflect light rays propagating vertically downward; a prism sheet positioned on top of the light guide plate, the prism sheet having reversed prism peaks protruding from a lower surface in a heptagonal cross section symmetric horizontally about a vertical line extending through an apex, left and right sides of each reversed prism peak being bent to define first, second, and third regions of each reversed prism peak; a diffusion sheet positioned on top of the prism sheet to increase
  • a backlight unit having a light guide plate using a polygonal prism structure
  • the backlight unit including a light guide plate having a plurality of prism peaks on an emission surface, each prism peak having a heptagonal cross section asymmetric horizontally about a vertical line extending through an apex, left and right sides of each prism peak of the light guide plate being bent to define first, second, and third regions of each prism peak; a reflection sheet positioned below the light guide plate to reflect light rays propagating vertically downward; a prism sheet positioned on top of the light guide plate, the prism sheet having reversed prism peaks protruding from a lower surface in a heptagonal cross section asymmetric horizontally about a vertical line extending through an apex, left and right sides of each reversed prism peak being bent to define first, second, and third regions of each reversed prism peak; a diffusion sheet positioned on top of the prism sheet
  • a liquid crystal display having a light guide plate using a polygonal prism structure
  • the liquid crystal display including a backlight unit including a light guide plate having a plurality of prism peaks on an emission surface, each prism peak having a heptagonal cross section symmetric horizontally about a vertical line extending through an apex, left and right sides of each prism peak of the light guide plate being bent to define first, second, and third regions of each prism peak, a reflection sheet positioned below the light guide plate to reflect light rays propagating vertically downward, a prism sheet positioned on top of the light guide plate, the prism sheet having reversed prism peaks protruding from a lower surface in a heptagonal cross section symmetric horizontally about a vertical line extending through an apex, left and right sides of each reversed prism peak being bent to define first, second, and third regions of each reversed prism peak, a diffusion sheet positioned on top of
  • a liquid crystal display having a light guide plate using a polygonal prism structure
  • the liquid crystal display including a backlight unit including a light guide plate having a plurality of prism peaks on an emission surface, each prism peak having a heptagonal cross section asymmetric horizontally about a vertical line extending through an apex, left and right sides of each prism peak of the light guide plate being bent to define first, second, and third regions of each prism peak, a reflection sheet positioned below the light guide plate to reflect light rays propagating vertically downward, a prism sheet positioned on top of the light guide plate, the prism sheet having reversed prism peaks protruding from a lower surface in a heptagonal cross section asymmetric horizontally about a vertical line extending through an apex, left and right sides of each reversed prism peak being bent to define first, second, and third regions of each reversed prism peak, a diffusion sheet positioned on
  • the inventive prism sheet and light guide plate based on a polygonal prism structure, as well as the backlight unit and LCD including the same, have the following advantages.
  • the prism sheet has polygonal reversed prism peaks on its light incident surface to improve both brightness and characteristics regarding the view of view.
  • the polygonal reversed prism peaks direct all light along paths that increase brightness.
  • the second regions of reversed prism peaks of the prism sheet also emit light in a direction that improves characteristics regarding the field of view. This both guarantees a wide field of view and prevents the loss of light due to the conventional prism structure.
  • the first, second, and third regions of polygonal prism peaks of the light guide plate refract, diffuse, and reflect incident light in different directions so that more uniform incident light is directed to the liquid crystal panel.
  • the second regions of prism peaks of the light guide plate emit light in a direction that improves characteristics regarding the field of view. This both guarantees a wide field of view and prevents the loss of light due to the conventional prism structure.
  • FIG. 1 shows the construction of a conventional backlight unit
  • FIG. 2 shows the construction of a prism sheet according to the prior art
  • FIG. 3 shows the construction of a reversed prism sheet according to the prior art
  • FIGs. 4-9 show the construction of light guide plates having polygonal prism peaks according to the present invention
  • FIGs. 10 and 11 show the detailed construction of polygonal prism peaks of a light guide plate according to the present invention
  • FIG. 12 shows the construction of a prism sheet having polygonal reversed prism peaks according to the present invention
  • FIG. 13 shows the path of incident light propagating through a polygonal reversed prism peak of a prism sheet according to the present invention
  • FIGs. 14 and 15 show the detailed construction of polygonal reversed prism peaks of a prism sheet according to the present invention
  • FIGs. 14 and 15 show the detailed construction of polygonal reversed prism peaks of a prism sheet according to the present invention
  • FIG. 16 and 17 show the results of a simulation regarding the path of incident light propagating through a simple reversed prism peak of a prism sheet and through a polygonal reversed prism peak according to the present invention, respectively;
  • FIG. 18 shows the characteristics regarding the path of incident light propagating through polygonal reversed prism peaks of a prism sheet according to the present invention;
  • FIG. 19 shows the coupling between a prism sheet and a light guide plate having polygonal prism peaks according to the present invention;
  • FIG. 20 shows another type of coupling between a prism sheet and a light guide plate having polygonal prism peaks according to the present invention; [46] FIGs.
  • FIG. 21-32 are photographs and graphs showing brightness distributions in relation to the field of view and the path of incident light propagating through simple reversed prism peaks, polygonal reversed prism peaks, and the pattern on the lower surface of the light guide plate;
  • FIG. 33 shows the construction of a backlight unit having polygonal reversed prism peaks according to the present invention.
  • FIG. 34 shows the construction of an LCD having polygonal reversed prism peaks according to the present invention;
  • FIG. 35 shows the construction of a backlight unit including a light guide plate having polygonal prism peaks and a prism sheet having polygonal reversed prism pea ks according to the present invention; [50] FIG.
  • FIG. 36 shows the construction of another backlight unit including a light guide plate having polygonal prism peaks and a prism sheet having polygonal reversed prism peaks according to the present invention
  • FIG. 37 shows the construction of an LCD including a light guide plate having polygonal prism peaks and a prism sheet having polygonal reversed prism peaks according to the present invention
  • FIG. 38 shows the construction of another LCD including a light guide plate having polygonal prism peaks and a prism sheet having polygonal reversed prism peaks according to the present invention.
  • FIGs. 4-9 show the construction of light guide plates having polygonal prism peaks according to the present invention.
  • FIGs. 10 and 11 show the detailed construction of polygonal prism peaks of a light guide plate according to the present invention.
  • the light guide plate 40 is adapted to condense incident light upward by diffusing, reflecting, and refracting it.
  • the light guide plate 40 has a plurality of polygonal prism peaks 41 protruding from the upper emission surface.
  • a plurality of polygonal prism peaks 41 are formed on the emission surface of the light guide plate 40 so that light incident from the light source is uniformly emitted toward the liquid crystal panel (not shown) by means of diffusion, reflection, and refraction.
  • each prism peak 41 of the light guide plate 40 has the shape of a heptagon, which is symmetric horizontally about a vertical line extending through its apex.
  • each prism peak 41 of the light guide plate 40 are bent to define first, second, and third regions 42a, 42b, and 42c of the prism peak 41.
  • each prism peak 41 of the light guide plate 40 has the shape of a heptagon symmetric horizontally about a vertical line extending through the apex
  • the prism peak 41 may have a heptagonal cross section that is asymmetric horizontallyabout the vertical line.
  • the cross section is not limited to the heptagon, and may have more vertices.
  • the first regions 42a of each prism peak 41 have one end extending upward from the lower surface of the light guide plate 40, i.e. the base region of the prism peak 41, at an angle.
  • the second regions 42b of each prism peak 41 are bent inward from the other end of the first regions 42a so that they extend upward at an angle.
  • the third regions 42c of each prism peak 41 are bent outward from the other end of the second regions 42b so that theyextend upward at an angle.
  • the left and right third regions 42c are joined at the apex 45 of the prism peak 41.
  • each prism peak 41 which are constructed as described above, is refracted, diffused, and reflected in different directions.
  • the geometric structure of the light guide plate having polygonal prism peaks according to the present invention will now be described with reference to FIGs. 10 and 11.
  • the interior angle ⁇ between the first and second regions 42a and 42b of each prism peak 41 constitutes a minor angle smaller than 180°
  • the interior angle ⁇ between the second and third regions 42b and 42c of the prism peak 41 constitutes a major angle larger than 180°.
  • first vertex 43 The point of intersection between the first and second regions 42a and 42b of each prism peak 41
  • second vertex 43 The point of intersection between the second and third regions 42b and 42c
  • the first and second vertices 43 and 44 of each prism peak 41 may be rounded to have a predetermined radius r, as shown in FIG. 11.
  • the height hi of the first vertices 43 of each prism peak 41 from its base region is larger than l ⁇ m.
  • the difference between the height h3 of the apex and the height h2 of the second vertices 44 i.e. h3-h2 is larger than l ⁇ m.
  • the height hi of the first vertices 43 of each prism peak 41 from the base region is in the range of l-12 ⁇ m
  • the height h2 of the second vertices44 from the base region is in the range of 13-23 ⁇ m.
  • the height h3 of the apex of each prism peak 41 from the base region is 24 ⁇ m, and the length w of the base region is 50m ⁇ .
  • the heights hi, h2, and h3 and the length w are not limited to the above-mentioned values, and may be varied to construct desired polygonal prism peaks.
  • the length w may be in the range of 20-80 ⁇ m.
  • the length w is 50 ⁇ m, 25 ⁇ m, or 24 ⁇ m.
  • the interior angle ⁇ between the base region of each prism peak 41 and the second regions 42b is calculated to be 0-43.73°.
  • the interior angle ⁇ between the base region and the first regions 42a of each prism peak 41 is 35-55°.
  • the interior angle between the opposite third regions 42c, which are joined at the apex 45, is 80-120°, preferably 110°.
  • the light guide plate having polygonal prism peaks according to the present invention is made of a material having a refractive index of 1.52-1.62, including polymethylmethacrylate (PMMA) and polycarbonate (PC)for injection molding.
  • the material can be selected from substances including mono- or di-acrylate series compounds, such as urethane acrylate and epoxy acrylate, and poly olefin series compounds, such as polyester, polysiloxane, and poly ether, so that UV curing is possible.
  • the light guide plate having polygonal prism peaks according to the present invention has a reflection pattern on its lower surface.
  • the light guide plate has a circular relief pattern formed in a direction parallel with the direction of extension of the prism peaks 41 and spaced from them.
  • the light guide plate has a prism relief pattern formed in a direction parallel with the direction of extension of the prism peaks 41 and spaced from them.
  • the light guide plate has a prism intaglio pattern formed in a direction parallel with the direction of extension of the prism peaks 41 and spaced from them.
  • the light guide plate has a circular relief pattern formed in a direction perpendicular to the direction of extension of the prism peaks 41 and spaced from them.
  • the light guide plate has a prism relief pattern formed in a direction perpendicular to the direction of extension of the prism peaks 41 and spaced from them.
  • the light guide plate has a prism intaglio pattern formed on a direction perpendicular to the direction of extension of the prism peaks 41 and spaced from them.
  • the reflection pattern on the lower surface of the light guide plate is not limited to the above mentioned types, and various types of patterns (e.g. dot pattern) may be used.
  • the interior angle ⁇ between the first and second regions 42a and 42b of each prism peak 41 may constitute a minor angle smaller than 180°
  • the interior angle ⁇ between the second and third regions 42b and 42c of the prism peak 41 may constitute a minor angle smaller than 180°
  • the height hi of the first vertices 43 of each prism peak 41 from the base region is larger than the height h2 of the second vertices 44.
  • the left and right vertices 43 act as additional apexes of the prism peak 41.
  • the height hi of the first vertices 43 from the base region may vary between adjacent prism peaks 41 of the light guide plate, while the height h3 of the central apex 45 remains the same, so that the height of the prism peaks 41 is irregularly repeated.
  • FIG. 12 shows the construction of a prism sheet having polygonal reversed prism peaks according to the present invention.
  • FIG. 13 shows the path of incident light propagating through a polygonal reversed prism peak of a prism sheet according to the present invention.
  • FIGs. 14 and 15 show the detailed construction of polygonal reversed prism peaks of a prism sheet according to the present invention.
  • the prism sheet 61 according to the present invention is adapted to condense light, which is incident on its lower surface, upward by refracting and reflecting it.
  • the prism sheet 61 has a plurality of reversed prism peaks 62 protruding from the lower surface.
  • a plurality of reversed prism peaks 62 are formed on the light incident surface of theprism sheet 61, which faces the emissionsurface of the light guide plate 40, and light incident from the light guide plate 40 is refracted and reflected so that it is uniformly emitted to the liquid crystal panel (not shown).
  • each reversed prism peak 62 of the prism sheet 61 has the shape of a heptagon, which is symmetric horizontally about a vertical line extending through its apex.
  • the left and right sides of each reversed prism peak 62 of the prism sheet have the shape of a heptagon, which is symmetric horizontally about a vertical line extending through its apex.
  • first, second, and third regions 62a, 62b, and 62c of the reversed prism peak 62 are bent to define first, second, and third regions 62a, 62b, and 62c of the reversed prism peak 62.
  • each reversed prism peak 62 of the prism sheet 61 has the shape of a heptagon symmetric horizontally about a vertical line extending through the apex
  • the reversed prism peak 62 may have a heptagonal cross section that is asymmetric horizontally about the vertical line.
  • the cross section is not limited to the heptagon, and may have more vertices.
  • the first regions 62a of each reversed prism peak 62 have one end extending downward from the lower surface of the prism sheet 61, i.e. the base region 65 of the reversed prism peak 62, at an angle.
  • the second regions 62b of each reversed prism peak 62 are bent inward from the other end of the first regions 62a so that they extend downward at an angle.
  • each reversed prism peak 62 is bent outward from the other end of the second regions 62b so that they extend downward at an angle.
  • the left and right third regions 62c are joined at the apex of the reversed prism peak 62.
  • Another portion of light incident on the reversed prism peak 62 is incident on the second region 62b on one side of the reversed prism peak 62 and undergoes primary reflection.
  • the portion of light is reflected secondarily by the base region 65, and is emitted in a direction that improves characteristics regarding the field of view.
  • FIG. 13 which briefly shows the path of light propagating through a reversed prism peak 62 of the prism sheet according to the present invention, that not all light is emitted by the reversed prism peak 62 in the upward direction (brightness improving direction) via the base region 65, but a portion of light is emitted by the second region 62b in a direction for improving characteristics regarding the field of view.
  • first vertex 63 The point of intersection between the first and second regions 62a and 62b of each reversed prism peak 62 will be referred to as a first vertex 63, and the point of intersection between the second and third regions 62b and 62c will be referred to as a second vertex 64.
  • the first and second vertices 63 and 64 of each reversed prism peak 62 may be rounded to have a predetermined radius r, as shown in FIG. 15.
  • the height hi of the first vertices 63 of each reversed prism peak 62 from its base region 65 is larger than l ⁇ m.
  • the difference between the height h3 of the apex and the height h2 of the second vertices 64 i.e. h3-h2 is larger than l ⁇ m.
  • the height hi of the first vertices 63 of each reversed prism peak 62 from the base region 65 is in the range of l-12 ⁇ m, and the height h2 of the second vertices 64 from the base region 65 is in the range of 13-23 ⁇ m.
  • each reversed prism peak 62 from thebase region 65 is 24 ⁇ m, and the length w of the base region 65 is 50 ⁇ m.
  • the heights hi, h2, and h3 and the length w are not limited to the above-mentioned values, and may be varied to construct desired polygonal reversed prism peaks.
  • the length w may be in the range of 20-80 ⁇ m.
  • the length w is 50 ⁇ m, 25 ⁇ m, or 24 ⁇ m.
  • the interior angle ⁇ between the base region 65 of each reversed prism peak 62 and the second regions 62b is calculated to be 0-43.73°.
  • each reversed prism peak 62 lie at a predetermined angle relative to the base region 65.
  • the interior angle ⁇ can be modified accordingly.
  • the interior angle ⁇ between the base region 65 and the first regions 62a of each reversed prism peak 62 is 40-55°.
  • the interior angle between the opposite third regions 62c of each reversed prism peak 62, which are joined at the apex, is 50-80°, preferably 68°.
  • the prism sheet having polygonal reversed prism peaks according to the present invention is made of a material having a refractive index of 1.52-1.62.
  • the material can be selected from substances including mono- or di-acrylate series compounds, such as urethane acrylate and epoxy acrylate, and polyolefin series compounds, such as polyester, polysiloxane, and polyether, so that UV curing is possible.
  • the polygonal reversed prism peaks 62 of the prism sheet 61 do not emit all light in the upward direction (brightness improving direction) via the base region 65, but emit a portion of light by the second regions 62b in a direction for improving characteristics regarding the field of view. This both guarantees a wide field of view and prevents the loss of light due to the conventional prism structure.
  • FIGs. 16 and 17 show the results of a simulation regarding the path of incident light propagating through a simple reversed prism peak of a prism sheet and through a polygonal reversed prism peak according to the present invention, respectively.
  • FIG. 18 shows the characteristics regarding the path of incident light propagating through polygonal reversed prism peaks of a prism sheet according to the present invention.
  • a conventionalprism sheet may be coupled to a light guide plate based on a polygonal prism structure, or a prism sheet having polygonal reversed prism peaks may be coupled to a conventional light guide plate.
  • FIG. 19 shows the coupling between a prism sheet and a light guide plate having polygonal prism peaks according to the present invention.
  • FIG. 20 shows another type of coupling between a prism sheet and a light guide plate having polygonal prism peaks accordingto the present invention.
  • the pattern arrangement direction of the prism peaks 41 of the light guide plate 40 is parallel with that of the reversed prism peaks 62 of the prism sheet 61.
  • the pattern arrangement direction of the prism peaks 41 of the light guide plate 40 is perpendicular to that of the reversed prism peaks 62 of the prism sheet 61.
  • FIGs. 21-32 are photographs and graphs showing brightness distributions in relation to the field of view and the path of incident light propagating through simple reversed prism peaks, polygonal reversed prism peaks, and the pattern on the lower surface of the light guide plate.
  • FIG. 21 is a graph showing a brightness distribution when a light guide plate having a conventional dot pattern is used. It is clear from FIG. 21 that the brightness has the largest value of 1 at an observing angle of 0°, and this value is used as the reference for data.
  • FIG. 22 compares a brightness distribution when a light guide plate having a conventional dot pattern is used with brightness distributions of a simple reversed prism sheet and a polygonal reversed prism sheet, respectively. It is clear from FIG. 22 that the simple reversed prism sheet has a brightness enhancement ratio of about 5.5, while the polygonal reversed prism sheet has a brightness enhancement ratio of about 8.
  • FIG. 23 shows an analysis of brightness of a reversed prism sheet when a light guide plate having a prism shape on theupper surface and a dot pattern on the lower surface is used. Particularly, FIG. 23 shows a brightness comparison based on an assumption that the brightness enhancement ratio of a conventionallight guide plate is 1.
  • the simple reversed prism sheet has a brightness enhancement ratio of 9.7127 at an angle of 4°, while the polygonal reversed prism sheet has a brightness enhancement ratio of 12.417 at an angle of -2°.
  • FIG. 24 shows the result of measuring brightness when a prism light guide plate having a prism shape on the upper surface and a prism pattern on the lower surface is solely used. It is clear from FIG. 24 that the prism pattern shape decreases the brightness at the center, but increases the brightness on the lateral surface.
  • FIG. 25 shows the brightness enhancement ratio when a light guide plate having a prism pattern on the upper and lower surfaces is used. It is clear from FIG. 25 that a sheet of a simple reversed prism structure has a brightness enhancement ratio of about 50, while a sheet ofa polygonal reversed prism structure has a brightness enhancement ratio of about 64.
  • FIG. 26 shows a brightness comparison when a light guide plate having a prism pattern on the upper and lower surfaces is used. It is clear from FIG. 26 that the brightness of a sheet of a simple reversed prism structure is 3.5nit, while the brightness of a sheet of a polygonal reversed prism structure is 4.3nit.
  • FIG. 27 shows a comparison in the orientation angle between a simple prism sheet and a polygonal prism sheet when a light guide plate of a dot pattern is used.
  • the center of the brightness distribution has shifted about 6°.
  • the brightness is highest at the center (ideal characteristics).
  • FIGs. 28 and 29 show light emission types when a light guide plate of a dot pattern is used.
  • a polygonal prism sheet as shown in FIG. 28, light emission is concentrated at the center (i.e. lies at the center of the Y-axis).
  • a simple prism sheet light emission is not concentrated at the center (i.e. lies at a distance from the center of the Y-axis).
  • FIG. 30 shows a comparison in the orientation angle between a simple prism sheet and a polygonal prism sheet when a light guide plate of a prism pattern is used.
  • the center of the brightness distribution has shifted about 9°.
  • the brightness is highest at the center (ideal characteristics).
  • FIGs. 31 and 32 show light emission types when a light guide plate of a prism pattern is used.
  • a polygonal prism sheet as shown in FIG. 31
  • light emission is concentrated at the center (i.e. lies at the center of the Y-axis).
  • a simple prism sheet as shown in FIG. 32
  • light emission is not concentrated at the center (i.e. lies below the center of the Y-axis).
  • the prism sheet accordingto an embodiment of the present invention which has been described above, is not only applicable to a backlight for an LCD, but can also be used to increase the brightness of a backlight using an organic EL display emitting light by itself.
  • FIG. 33 shows the construction of a backlight unit having polygonal reversed prism peaks accordingto the present invention.
  • FIG. 34 shows theconstruction of an LCD having polygonal reversed prism peaks according to the present invention.
  • the backlight unit having polygonal reversed prism peaks includes a light guide plate 100 having an incident surface, on which light rays from a light source are incident and are diffused, reflected, and refracted to change the direction of propagation so that they are uniformly emitted upward; a reflection sheet 400 for reflecting light rays propagating vertically downward a prism sheet 200 positioned on top of the light guide plate 100, the prism sheet 200 having reversed prism peaks protruding from the lower surface to have a heptagonal cross section symmetric horizontally about a vertical line extending through the apex, the left and right sides of each reversed prism peak being bent to define first, second, and third regions of the reversed prism peak; a diffusion sheet 300 positioned on top of the prism sheet 200 to increase the uniformity of light; and a protection sheet 500 for stabilizing the color coordinate and protecting the sheets.
  • the reversed prism peaks may have a heptagonal cross section that is asymmetric horizontally about the vertical line.
  • the cross section is not limited to the heptagon, and the backlight unit may include a prism sheet having reversed prism peaks with more vertices.
  • the LCD having polygonal reversed prism peaks includes a backlight unit and a liquid crystal panel 600.
  • the backlight unit includes a light guide plate 100 having an incident surface, on which light rays from a light source are incident and are diffused, reflected, and refracted to change the direction of propagation so that they are uniformly emitted upward; a reflection sheet 400 for reflecting light rays propagating vertically downward; a prism sheet 200 positioned on top of the light guide plate 100, the prism sheet 200 having reversed prism peaks protruding from the lower surface to have a heptagonal cross section symmetric horizontally about a vertical line extending through theapex, the left and right sides of each reversed prism peak being bent to define first, second, and third regions of the reversed prism peak; a diffusion sheet 300 positioned on top of the prism sheet 200 to increase the uniformity of light; and a protection sheet 500 for stabilizing the color coordinate and protecting the sheets.
  • the liquid having an incident surface, on which light ray
  • the reversed prism peaks may have a heptagonal cross section that is asymmetric horizontally about the vertical line.
  • the cross section is not limited to the heptagon, and a prism sheet having reversed prism peaks with more verticesmay be used for the backlight unit and the LCD.
  • the polygonal reversed prism peaks of the prism sheet, the backlight unit, and the LCD according to an embodiment of the present invention do not emit all light in the upward direction (brightness improving direction) via the base region of the reversed prism peaks, but emit a portion of light by the second regions of the reversed prism peaks in a direction for improving characteristics regarding the field of view. This both guarantees a wide field of view and prevents the loss of light due to the conventional prism structure.
  • FIGs. 33 and 34 also show positionsA and B on the light guide plate 100, in which a light source can be installed.
  • the light source may be installedin position A or B on the lateral surface of the light guide plate 100.
  • a backlight unit using a light guide plate having polygonal prism peaks on its light emission surface and a prism sheet having polygonal reversed prism peaks according to the present invention will now be described.
  • FIG. 35 shows the construction of a backlight unit including a light guide plate having polygonal prism peaks and a prism sheet having polygonal reversed prism peaks according to the present invention.
  • FIG. 36 shows the construction of another backlight unit including a light guide plate having polygonal prism peaks and a prism sheet having polygonal reversed prism peaks according to the present invention.
  • abacklight unit includes a light guide plate 100 having a plurality of prism peaks formed on its emission surface to have a heptagonal cross section symmetric horizontally about a verticalline extending through the apex, the left and right sides of each prism peak being bent to define first, second, and third regions of the prism peak, the light guide plate 100 having an incident surface, on which light rays from a light source are incident and are diffused, reflected, and refracted to change the direction of propagation so that they are uniformly emitted upward; a reflection sheet 400 positioned below the light guide plate 100 to reflect light rays propagating vertically downward; a prism sheet 200 positioned on top of the light guide plate 100, the prism sheet 200 having reversed prism peaks protruding from the lower surface to have a heptagonal cross section symmetric horizontally about a vertical line extending through the apex, the left and right sides of each reversed prism peak being
  • FIG. 35 shows positions A and B on the light guide plate 100, in which a light source can be installed.
  • the light source may be installed in position A or B on the lateral surface of the light guide plate 100.
  • another backlight unit includes a light guide plate 100 having a plurality of prism peaks formed on its emission surface to have a heptagonal cross section symmetric horizontally about a vertical line extending through the apex, the left and right sides of each prism peak being bent to define first, second, and third regions of the prism peak, the light guide plate 100 having an incident surface, on which light rays from a light source are incident and are diffused, reflected, and refracted to change the direction of propagation so that they are uniformly emitted upward; a reflection sheet 400 positioned below the light guide plate 100 to reflect light rays propagating vertically downward; a prism sheet 200 positioned on top of the light guide plate 100, the prism sheet 200 having reversed prism peaks protruding from the lower surface to have a heptagonal cross section symmetric horizontally about a vertical line extending through the apex, the left and right sides of each reversed prism peak being bent
  • FIG. 36 shows positions A and B on the light guide plate 100, in which a light source can be installed.
  • the light source may be installed in position A or B on the lateral surface of the light guide plate 100.
  • the prism peaks of the light guide plate and the reversed prism peaks of the prism sheet may have a heptagonal cross section that is asymmetric horizontally about the vertical line.
  • the cross section is not limited to the heptagon, and prism peaks and reversed prism peaks having more vertices may be used to constitute the backlight unit.
  • the diffusion sheet 300 may be a separate component as mentioned above.
  • the upper surface of the prism sheet 200 may be subjected to diffusion treatment so that no separate diffusion sheet 300 is necessary to constitute the backlight unit.
  • FIG. 37 shows the construction of an LCD including a light guide plate having polygonal prism peaks and a prism sheet having polygonal reversed prism peaks according to the present invention.
  • FIG. 38 shows the construction of another LCD including a light guide plate having polygonal prism peaks and a prism sheet having polygonal reversed prism peaks according to the present invention.
  • an LCD according to the present invention includes a back- lightunit and a liquid crystal panel 600.
  • the backlight unit includes a light guide plate 100 having a plurality of prism peaks formed on its emission surface to have a heptagonal cross section symmetric horizontally about a vertical line extending through the apex, the left and right sides of each prism peak being bent to define first, second, and third regions of the prism peak, the light guide plate 100 having an incident surface, on which light rays from a light source are incident and are diffused, reflected, and refracted to change the direction of propagation so that they are uniformly emitted upward; a reflection sheet 400 positioned below the light guide plate 100 to reflect light rays propagating vertically downward; a prism sheet 200 positioned on top of the light guide plate 100, the prism sheet 200 having reversed prism peaks protrudingfrom the lower surface to have a heptagonal cross section symmetric horizontally about a vertical line extending through the a
  • the liquid crystal panel 600 is coupled to the backlight unit, and has liquid crystal cells arranged in an active matrix type to adjust the degree of transmission of projected light so that images are displayed by the light projected by the backlight unit.
  • the prism peaks of the light guide plate 100 and the reversed prism peaks of the prism sheet 200 are formed in the same direction.
  • FIG. 37 shows positions A and B on the light guide plate 100, in which a light source can be installed.
  • the light source may be installed in position A or B on the lateral surface of the light guide plate 100.
  • another LCD includes a backlightunit and a liquid crystal panel 600.
  • the backlight unit includes a light guide plate 100 having a plurality of prism peaks formed on its emission surface to have a heptagonal cross section symmetric horizontally about a vertical line extending through the apex, the left and right sides of each prism peak being bent to define first, second, and third regions of the prism peak, the light guide plate 100 having an inc ident surface, on which light rays from a light source are incident and are diffused, reflected, and refracted to change the direction of propagation so that they are uniformly emitted upward; a reflection sheet 400 positioned below the light guide plate 100 to reflect light rays propagating vertically downward; a prism sheet 200 positioned on top of the light guide plate 100, the prism sheet 200 having reversed prism peaks protruding from the lower surface to have a heptagonal cross section symmetric horizontally about a vertical line extending through the
  • the liquid crystal panel 600 is coupled to the backlight unit, and has liquid crystal cells arranged in an active matrix type to adjust the degree of transmission of projected light so that images are displayed by the light projected by the backlight unit.
  • the prism peaks of the light guide plate 100 and the reversed prism peaks of the prism sheet 200 are formed in perpendicular directions.
  • FIG. 38 shows positions A and B on the light guide plate 100, in which a light source can be installed.
  • the light source may be installedin position A or B on the lateral surface of the light guide plate 100.
  • the diffusion sheet 300 may be a separate component as mentioned above.
  • the upper surface of the prism sheet 200 may be subjected to diffusion treatment so that no separate diffusion sheet 300 is necessary to constitute the backlight unit.
  • the prism peaks of the light guide plate and the reversed prism peaks of the prism sheet may have a heptagonal cross section that is asymmetric horizontally about the vertical line.
  • the cross section is not limited to the heptagon, and prism peaks and reversed prism peaks having more vertices may be used to constitute the backlight unit and the
  • the inventive prism sheet and light guide plate having reversed prism peaks and prism peaks, respectively, based on a polygonal prism structure, as well as a backlight unit and an LCD using the same improve both brightness and characteristics regarding the field of view.

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

Abstract

L'invention concerne une feuille à prismes et une plaque-guide de lumière comportant des pics prismatiques inversés et des pics prismatiques, respectivement, reposant sur une structure prismatique polygonale, ainsi qu'une unité de rétro-éclairage et un LCD utilisant ces dernières pour améliorer à la fois la luminosité et les caractéristiques liées au champ de vision.
PCT/KR2008/000972 2007-05-11 2008-02-19 Feuille à prismes et lgp utilisant une structure prismatique polygonale, blu et lcd utilisant lesdites feuilles et lgp WO2008140176A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
KR1020070046050A KR20080100017A (ko) 2007-05-11 2007-05-11 다각형의 역 프리즘 시트 그리고 이를 갖는 백라이트 유닛및 액정디스플레이 장치
KR10-2007-0046050 2007-05-11
KR1020070082693A KR20090018318A (ko) 2007-08-17 2007-08-17 다각형의 프리즘 구조를 이용한 도광판과 백라이트 유닛그리고 액정디스플레이 장치
KR10-2007-0082693 2007-08-17

Publications (1)

Publication Number Publication Date
WO2008140176A1 true WO2008140176A1 (fr) 2008-11-20

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ID=40002350

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Application Number Title Priority Date Filing Date
PCT/KR2008/000972 WO2008140176A1 (fr) 2007-05-11 2008-02-19 Feuille à prismes et lgp utilisant une structure prismatique polygonale, blu et lcd utilisant lesdites feuilles et lgp

Country Status (1)

Country Link
WO (1) WO2008140176A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011092250A1 (fr) 2010-01-28 2011-08-04 Total Petrochemicals Research Feluy Procédé pour démarrer d'un procédé pour fabriquer des polymères vinyliques aromatiques expansibles
CN102565916A (zh) * 2011-11-17 2012-07-11 友达光电股份有限公司 导光板、背光模块与显示装置

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000231103A (ja) * 1999-02-09 2000-08-22 Mitsubishi Rayon Co Ltd レンズシートおよびそれを用いたバックライト、液晶表示装置
US20050254259A1 (en) * 2002-06-24 2005-11-17 Tomoyoshi Yamashita Light source device and light polarizing element
KR100624192B1 (ko) * 2005-08-17 2006-09-13 주식회사 나모텍 프리즘시트

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000231103A (ja) * 1999-02-09 2000-08-22 Mitsubishi Rayon Co Ltd レンズシートおよびそれを用いたバックライト、液晶表示装置
US20050254259A1 (en) * 2002-06-24 2005-11-17 Tomoyoshi Yamashita Light source device and light polarizing element
KR100624192B1 (ko) * 2005-08-17 2006-09-13 주식회사 나모텍 프리즘시트

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011092250A1 (fr) 2010-01-28 2011-08-04 Total Petrochemicals Research Feluy Procédé pour démarrer d'un procédé pour fabriquer des polymères vinyliques aromatiques expansibles
CN102565916A (zh) * 2011-11-17 2012-07-11 友达光电股份有限公司 导光板、背光模块与显示装置
CN102565916B (zh) * 2011-11-17 2014-05-28 友达光电股份有限公司 导光板、背光模块与显示装置

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