Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/02—Diffusing elements; Afocal elements
  • G02B5/0268—Diffusing elements; Afocal elements characterized by the fabrication or manufacturing method
• • 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
  • G02B6/0081—Mechanical or electrical aspects of the light guide and light source in the lighting device peculiar to the adaptation to planar light guides, e.g. concerning packaging
  • G02B6/0086—Positioning aspects
  • G02B6/0088—Positioning aspects of the light guide or other optical sheets in the package
• • 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
  • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
  • G02B6/0023—Means for improving the coupling-in of light from the light source into the light guide provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
  • G02B6/0031—Reflecting element, sheet or layer
• • 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
  • G02B6/004—Scattering dots or dot-like elements, e.g. microbeads, scattering particles, nanoparticles
  • G02B6/0043—Scattering dots or dot-like elements, e.g. microbeads, scattering particles, nanoparticles provided on the surface 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
  • G02B6/0035—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
  • G02B6/0045—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 by shaping at least a portion of the light guide
  • G02B6/0046—Tapered light guide, e.g. wedge-shaped 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
  • G02B6/0051—Diffusing sheet or layer
• • 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
  • G02B6/0055—Reflecting element, sheet or layer
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
  • G02B6/0033—Means for improving the coupling-out of light from the light guide
  • G02B6/0058—Means for improving the coupling-out of light from the light guide varying in density, size, shape or depth along the light guide
  • G02B6/0061—Means for improving the coupling-out of light from the light guide varying in density, size, shape or depth along the light guide to provide homogeneous light output intensity
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
  • G02B6/0065—Manufacturing aspects; Material aspects
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
  • G02B6/0066—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form characterised by the light source being coupled to the light guide
  • G02B6/0073—Light emitting diode [LED]
• • 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
  • G02B6/0081—Mechanical or electrical aspects of the light guide and light source in the lighting device peculiar to the adaptation to planar light guides, e.g. concerning packaging
  • G02B6/0086—Positioning aspects
  • G02B6/009—Positioning aspects of the light source in the package

Definitions

• the present disclosure relates to a method of fabricating a light guide plate (LGP) , an LGP fabricated thereby, and an illumination device having the same and, more particularly, to a method of fabricating an LGP, an LGP fabricated thereby, and an illumination device having the same, in which a luminous point through which light is extracted can be prevented from being viewed by a front observer, a process can be simplified, and light distribution similar to Lambertian distribution can be obtained.
• LGP light guide plate
• a light guide plate is implemented using a high transparency substrate of, for example, an acrylic or polycarbonate.
• the LGP distributes light therein using total internal reflection that occurs when light travels from a medium having a higher optical refractive index to a medium having a lower optical refractive index.
• the LGP must have a plurality of light extraction points, at which light is extracted outwardly.
• Such light extraction points are generally manufactured by a method of machining V-shaped grooves in the LGP, a method of fabricating lenses using inkjets, and as illustrated in FIG. 10, a method of printing patterned dots 5 on the surface of an LGP 3 by screen printing.
• a diffuser sheet must be additionally provided, due to significant distances between the dots 5.
• Patent Document 1 Korean Patent No. 10-0656896 (December
• Various aspects of the present disclosure provide a method of fabricating a light guide plate (LGP) , an LGP fabricated thereby, and an illumination device having the same, in which a luminous point through which light is extracted can be prevented from being viewed by a front observer, a process can be simplified, and light distribution similar to Lambertian distribution can be obtained.
• LGP light guide plate
• a method of fabricating a light guide plate used in an edge-lit illumination device may include: preparing a light guide plate including a first surface facing a front observer and through which light is irradiated, a second surface opposite to the first surface, and a third surface connected to a peripheral portion of the first surface and a peripheral portion of the second surface to connect the first surface and the second surface, the third surface facing a light- emitting diode; and fabricating a light-scattering layer by printing a printing solution including light-scattering particles on an overall area of the second surface.
• the light scattering layer may be fabricated by at least one of a first method of controlling the printing such that a density of the light-scattering particles gradually increases with increases in a distance from the light-emitting diode facing at least one surface of the third surface and a second method of controlling the printing such that a thickness of the light-scattering layer gradually increases with increases in the distance from the light-emitting diode facing at least one surface of the third surface .
• the method may further include manufacturing the printing solution before fabricating the light-scattering layer.
• the printing solution may be manufactured by adding the light-scattering particles to the printing solution, such that an amount of the light-scattering particles ranges, by weight, from 0.1% to 5% of an amount of the printing solution.
• the printing solution may be manufactured by adding the light-scattering particles to the printing solution, the light scattering particles including at least one selected from among Ti0 2 , Zr0 2 , BaTi03, and Sn0 2 .
• the first method may control the printing such that numbers of the light-scattering particles per unit area vary by at least 1.2 times according to positions.
• the first method may control the printing such that the light-scattering layer is formed to have a uniform thickness on the overall area of the second surface.
• the second method may control the printing such that the thickness of the light-scattering layer according to positions ranges from lpm to 5 pm.
• the method may further include curing the light-scattering layer after fabricating the light-scattering layer.
• a light guide plate may include: a light guide plate body including a first surface facing a front observer and through which light is irradiated, a second surface opposite to the first surface, and a third surface connected to a peripheral portion of the first surface and a peripheral portion of the second surface to connect the first surface and the second surface, the third surface facing a light-emitting diode; and a light-scattering layer fabricated on an overall area of the second surface, the light-scattering layer including a matrix layer and a number of light-scattering particles dispersed in the matrix layer.
• the thickness of the light-scattering layer may gradually increase with increases in a distance from the light-emitting diode facing at least one surface of the third surface.
• a light guide plate may include: a light guide plate body including a first surface facing a front observer and through which light is irradiated, a second surface opposite to the first surface, and a third surface connected to a peripheral portion of the first surface and a peripheral portion of the second surface to connect the first surface and the second surface, the third surface facing a light-emitting diode; and a light-scattering layer fabricated on an overall area of the second surface, the light-scattering layer including a matrix layer and a number of light-scattering particles dispersed in the matrix layer.
• a light-scattering layer fabricated on an overall area of the second surface, the light-scattering layer including a matrix layer and a number of light-scattering particles dispersed in the matrix layer.
• the light-scattering layer may be fabricated at a uniform thickness on an overall area of the second surface.
• the surface of the light-scattering layer may be a flat surface .
• the surface roughness of the light-scattering layer may be 100 nm or less.
• the thickness of the light-scattering layer according to positions ranges from lpm to 5 pm.
• the light-scattering particles may be formed from a material having a higher refractive index than that of the matrix layer .
• the light-scattering particles may be formed from at least one selected from among Ti0 2 , Zr0 2 , BaTi03, and Sn0 2 .
• the light guide plate may have a hazing value of 30% or less and a transmittance of 50% or more.
• an illumination device may include: the above-described light guide plate; at least one light-emitting diode disposed to face at least one surface of the third surface defined as a side surface of the light guide plate; and a frame providing a space in which the light guide plate and the light-emitting diode are disposed.
• the light-emitting diode When the light-emitting diode is on, light may be irradiated through the first surface defined as a front surface of the light guide plate and the second surface defined as a rear surface of the light guide plate. When the light-emitting diode is off, the front observer facing the first surface can observe the second surface through the light guide plate.
• the illumination device may further include a reflector disposed adjacent to the second surface defined as a rear surface of the light guide plate.
• the light-scattering layer including the light-scattering particles is fabricated on the overall area of the rear surface of the LGP, with respect to a front observer, in a single printing process .
• This can accordingly prevent the phenomenon in which luminous points through which light is extracted are visible to a front observer, i.e. the problem in which stains occurring in inkjet printing in the related art, due to pattern mismatch or regularly patterned shapes, are visible to a front observer .
• the light-scattering layer can be fabricated in a single printing process, the diffuser sheet disposed in front of the LGP can be omitted, and an additional layer, such as a low surface energy layer required in the case of fabrication of lenses, may be unnecessary, thereby simplifying the LGP fabrication process.
• the density of the light-scattering particles with respect to the printing solution is controlled to gradually increase with increases in the distance from the LED disposed on the side surface of the LGP or the thickness of the light-scattering particles is controlled to gradually increase with increases in the distance from the LED disposed on the side surface of the LGP. This can consequently prevent the problem of an excessive quantity of light from exiting areas adjacent to the LED and obtain light distribution similar to Lambertian distribution.
• the illumination device may be provided as a transparent illumination device. That is, when the LED is on, light can be irradiated through both the front and rear surfaces of the LGP, and when the LED is off, any object behind the illumination device is visible to a front observer.
• FIG. 1 is a process flowchart illustrating a method of fabricating an LGP according to an exemplary embodiment
• FIG. 2 is a conceptual diagram schematically illustrating an LGP fabricated according to an exemplary embodiment
• FIGS. 3 and 4 are conceptual diagrams schematically illustrating an illumination device including an LGP fabricated according to an exemplary embodiment
• FIG. 5 is an image obtained by observing an LGP fabricated by Comparative Example 1;
• FIG. 6 is a light distribution diagram of an LGP fabricated by Comparative Example 1 of the present disclosure.
• FIG. 7 is a graph illustrating position-specific brightness uniformity depending on the concentration of LGPs fabricated by Comparative Examples 1 and 2 of the present disclosure
• FIG. 8 is a light distribution diagram of an LGP fabricated by Example 1 of the present disclosure.
• FIGS. 9A and 9B are images illustrating an illumination device in which the LGP fabricated by Example 1 of the present disclosure is used.
• FIGS. 10 and 11 are schematic views illustrating LGPs of the related art. DETAILED DESCRIPTION
• the method of fabricating an LGP is a method of fabricating an LGP 100 used in an edge-lit illumination device 10 (see FIGS. 3 and 4) that is lit by light-emitting diodes (LEDs) disposed on an edge thereof.
• LEDs light-emitting diodes
• the method of fabricating a LGP according to an exemplary embodiment includes a LGP preparation step S110 and a light-scattering layer fabrication step S130.
• the method of fabricating a LGP according to an exemplary embodiment may further include a printing solution manufacturing step S120 before the light-scattering layer fabrication step S130.
• an LGP 100 is prepared as a transparent plate.
• the LGP 100 may be implemented using a substrate formed from an acrylic or glass .
• a transparent LED illumination device may be provided, so that an image behind the device is visible.
• the LGP 100 may have a hazing value of 30% or lower and a transmittance of 50% or higher.
• a surface of the LGP 100, facing a front observer, and through which light is irradiated, will be referred to as a "front surface”
• a surface of the LGP 100 opposite to the front surface will be referred to as a “rear surface”
• surfaces of the LGP 100 connected to peripheries of the front surface and peripheries of the rear surface to connect the front surface and the rear surface will be referred to as side surfaces of the LGP 100.
• a printing solution including light-scattering particles 130 is manufactured.
• the content of the light-scattering particles 130 in the printing solution is required to be very small, when compared to a dot pattern printing solution of the related art.
• the light-scattering layer 140 is fabricated in the light scattering layer fabrication step S130, to be described later, the light-scattering layer 140 provides a surface, instead of forming dot shapes of the related art, thereby increasing the overall area. Accordingly, a large quantity of light exits the areas adjacent to the LED 200.
• the content of the light-scattering particles 130 is set to be very small, when compared to the dot pattern printing solution of the related art.
• the light-scattering particles 130 may be added to the printing solution such that the content thereof with respect to the printing solution may range, by weight, from 0.1% to 5%, and preferably, may be 2% or less.
• the light scattering particles 130 may be implemented using a material having a different refractive index from that of the material of the printing solution, and particularly, a higher refractive index than that of the material of the printing solution.
• the light-scattering particles 130 added to the printing solution may be at least one selected from among, but not limited to, Ti0 2 , Zr0 2 , BaTi0 3 , and Sn0 2 .
• the light-scattering particles 130 are not limited to the above-mentioned materials. Rather, the light-scattering particles 130 may be implemented using a variety of other materials having a higher refractive index than that of the material of the printing solution.
• a mixture solution of polysiloxane and dipropylene glycol methyl ether (DPM) may be used as the printing solution.
• DPM dipropylene glycol methyl ether
• a mixture of hexamethylene diacrylate, exo-1, 7, 7-trimethylbicyclo [2.2.1] hept-2-yl acrylate, benzyl acrylate, 2-methoxyethyl acrylate, and diphenyl ( 2 , 4 , 6- trimethylbenzoyl ) phosphine oxide may be used as the printing solution .
• the printing solution is printed on the overall area of the rear surface of the LGP 100, thereby forming a continuous light-scattering layer 140, with the light-scattering particles 130 being dispersed therein.
• the printing solution including the light-scattering particles 130 having a significantly low content, is printed on the overall area of the rear surface of the LGP 100, as described above, the surface of the light-scattering layer 140 forms a flat surface. That is, none of the light-scattering particles 130 protrude from the surface of light-scattering layer 140.
• a surface roughness (Ra) of 100 nm or less was measured from a lOpmXIOpm area of the surface of the light-scattering layer 140 using an atomic force microscope (AFM) , in a luminous condition in which diffuse reflection occurs on the surface of the light-scattering layer 140.
• the light-scattering particles 130 only dispersed within the scattering layer 140, as described above, can prevent the phenomenon in which luminous points through which light is extracted are visible to a front observer, i.e. the problem in which stains occurring in inkjet printing in the related art, due to pattern mismatch or regularly patterned shapes, are visible to a front observer.
• the light-scattering layer 140 is fabricated to form a single surface covering the overall area of the rear surface of the LGP 100, instead of being fabricated as dot-patterned spots of the related art, a diffuser sheet disposed in front of the LGP in the related art can be omitted and an additional layer, such as a low surface energy layer required in the case of fabrication of lenses, may be unnecessary, thereby simplifying an LGP fabrication process.
• the light-scattering layer fabrication step S130 the light-scattering layer 140 can be fabricated in a single printing process, thereby simplifying the fabrication process.
• the light-scattering layer fabrication step S130 uses at least one of a first method of controlling the printing process such that the content of light-scattering particles 130 in the light scattering layer 140 varies in a position-specific manner, depending on the distance from the LED 200 facing at least one surface of the side surfaces of the LGP 100, and a second method of controlling the printing process such that the thickness of the light-scattering layer 140 varies in a position-specific manner, depending on the distance from the LED 200 facing at least one surface of the side surfaces of the LGP 100.
• This feature is intended to adjust the difference of light extraction efficiency depending on the distance from the LED 200 disposed on the side surface of the LGP 100. That is, the printing process is controlled as described above, since it is necessary to decrease the light extraction efficiency in an area closer to the LED 200 while increasing the light extraction efficiency in an area located farthest from the LED 200 in order to realize uniform light distribution across the entirety of areas.
• the first method used in the light scattering layer fabrication step S130 may control the printing process such that the density of the light-scattering particles per unit area, with respect to the printing solution, gradually increases with increases in the distance from the LED 200 facing at least one surface of the side surfaces of the side surfaces of the LGP 100.
• the printing process may be controlled such that the numbers of the light-scattering particles 130 per unit area vary by at least 1.2 times according to positions.
• the printing process may be controlled such that the number of the light-scattering particles 130 dispersed within a portion of the light-scattering layer 140, located adjacently to the LED 200, is 50% while the number of the light scattering particles 130 dispersed within a portion of the light-scattering layer 140, located farthest from the LED 200, is 80%.
• the printing process may be controlled such that the thickness of the light-scattering layer 140 is uniform across the overall area of the rear surface of the LGP 100.
• two solutions including the light-scattering particles formed from BaTi0 3 i.e.
• a solution in which the weight ratio of the light-scattering particles is 0.5% and a solution in which the weight ratio of the light-scattering particles is 1.2% are prepared.
• an inkjet head able to use both of the two solutions, is prepared.
• a light-scattering layer is printed at a uniform thickness using the inkjet head, such that the numbers of the light-scattering particles per unit volume vary according to the positions.
• the light scattering layer having the uniform printing thickness and different numbers of light-scattering particles per unit volume can be printed and fabricated by continuously changing the ratios of injection of the two solutions while maintaining the entire printing density fixed.
• the second method used in the light-scattering layer fabrication step S130 may control the printing process such that the thickness of the light-scattering layer 140 gradually increases with increases in the distance from the LED 200 facing at least one surface of the side surfaces of the LGP 100.
• the printing process may be controlled such that the thickness of the light-scattering layer 140 ranges from lpm to 5 pm according to positions.
• the printing process may be controlled such that the thickness of a portion of the light-scattering layer 140, located adjacently to the LED 200, is 1 pm, while the thickness of a portion of the light-scattering layer 140, located farthest from the LED 200, is 5 pm.
• the printing process may be controlled such that the thickness of the portion of the light-scattering layer 140, located adjacently to the LED 200, is 1 pm, and then the thickness of the light-scattering layer 140 gradually increases, for example, in the form of a Gaussian distribution curve, so that the thickness of the portion of the light-scattering layer 140, located farthest from the LED 200, is finally 5 pm.
• the thickness of the light-scattering layer 140 is less than 1 pm, light distribution similar to similar to Lambertian distribution cannot be obtained.
• the thickness of the light-scattering layer 140 exceeds 5 pm, it is difficult to dry the printed light-scattering layer 140, which is problematic.
• the LED 200 has been described as only being disposed on a single side surface of the LGP 100 according to the exemplary embodiment, the LED 200 may be disposed on opposite side surfaces of the LGP 100.
• the light-scattering layer 140 may be fabricated such that the thickness of a portion thereof, located in a central portion of the LGP 100, is the greatest. That is, the thickest portion of the light-scattering layer 140, the thickness of which is 5 pm, may be provided on the central area of the LGP 100.
• the density of the light-scattering particles 130 with respect to the printing solution may be controlled so as to gradually increase with increases in the distance from the LED 200 facing at least one surface of the side surfaces of the LGP 100
• the thickness of the light scattering particles 130 may be controlled so as to gradually increase in the form of a Gaussian distribution curve
• the thickness of the light-scattering particles 130 may be controlled so as to gradually increase while the density of the light-scattering particles 130 with respect to the printing solution is controlled so as to gradually increase with increases in the distance from the LED 200 facing at least one surface of the side surfaces of the LGP 100. This can consequently prevent the problem of an excessive quantity of light from exiting the areas adjacent to the LED 200, and obtain light distribution (see FIG. 8) similar to Lambertian distribution .
• the method of fabricating a LGP according to the exemplary embodiment may further include a light-scattering layer curing step S140 of curing the light-scattering layer 140 fabricated on the overall area of the rear surface of the LGP 100 in the light-scattering layer fabrication step S130.
• the light-scattering layer curing step S140 the light-scattering layer 140 may be cured using an inline ultraviolet (UV) ray curing device.
• UV inline ultraviolet
• the LGP 100 includes an LGP body 110, with the LED 200 being disposed adjacently a side surface thereof and the light-scattering layer 140 fabricated on the overall area of the rear surface of the LGP body 110.
• the light scattering layer 140 includes a matrix layer 120 and the number of light-scattering particles 130 dispersed in the matrix layer 120.
• the surface of the light-scattering layer 140 forms a flat surface, with a surface roughness (Ra) thereof being, for example, 100 nm or less.
• the thickness of the light-scattering layer 140 gradually increases in the form of a Gaussian distribution curve, with increases in the distance from the side surface of the LGP 100 on which the LED 200 is disposed.
• the thickness of the portion of the light scattering layer 140, most adjacent to the LED 200 may be the smallest thickness of 1 pm, whereas the thickness of the portion of the light-scattering layer 140, located farthest from the LED 200, may be the smallest thickness of 5 pm.
• the dispersion density of the number of light scattering particles 130 may gradually increase, with increases in the distance from the side surface of the LGP 100 on which the LED 200 is disposed.
• the light-scattering particles 130 may be formed from a material, the refractive index of which is higher than that of the material of the light-scattering layer 140.
• the light-scattering particles 130 may be formed from at least one selected from among, but not limited to, T1O2, Zr0 2 , BaTi03, and Sn0 2 .
• the light-scattering layer 140 may be fabricated at a uniform thickness across the overall area of the rear surface of the LGP 100.
• the LGP 100 fabricated by the method of fabricating an LGP according to an exemplary embodiment, as described above, may be used in an illumination device 10.
• the illumination device 10 is an edge-lit illumination device, including the LGP 100 and the LED 200, as described above, and a frame 300.
• the LED 200 is disposed on at least one side surface of the LGP 100. That is, the LED 200 may be disposed on the left side surface, the right side surface, or both the left and right side surfaces of the LGP 100, when viewed in the drawing. Here, at least one LED 200 may be disposed on each side surface.
• the frame 300 provides a space in which the LGP 100 and the LED 200 are disposed. As illustrated in FIG. 3, the frame 300 may be configured to surround entire portions of the LGP 100, except for an area of the LGP 100 through which light is irradiated (i.e. an upper portion in the drawing) .
• a reflector sheet 400 may be disposed between the rear surface of the LGP 100 and the frame 300 to forwardly reflect light that has exited the rear surface of the LGP 100.
• the frame 300 may be configured to expose the front and rear surfaces of the LGP 100. That is, the frame 300 in the shape of a rectangular doorframe may be coupled to the LGP 100.
• the LED 200 when the LED 200 is on, light is irradiated in opposite directions through the exposed front and rear surfaces of the LGP 100.
• the LED 200 When the LED 200 is off, the LGP 100 has a hazing value of 30% or less and a transmittance of 50% or more, so that a front observer can see an image behind the illumination device 10 through the transparent LGP 100.
• a glass LGP having a size of 120mmX120mmX2mm was prepared.
• white ink including, by weight, 12% of Ti0 2 particles, available from Atech innovations GmbH, was prepared.
• the white ink was a mixture of hexamethylene diacrylate, exo-1, 7, 7-trimethylbicyclo [2.2.1] hept-2-yl acrylate, benzyl acrylate, 2-methoxyethyl acrylate, and diphenyl ( 2 , 4 , 6- trimethylbenzoyl ) phosphine oxide.
• a concentration gradient was imparted by performing printing on the LGP such that specific areas of the LGP were unprinted, in a printing density of 400X400 dpi (drops per inch) , and by adjusting the size of liquid drops to be 12 pL .
• the IrisTM Glass plate was cut and then cleaned using an inline ultrasonic cleaner.
• a solution including, by weight, 2% of BaTi0 3 powder was prepared.
• a dipropylene glycol methyl ether (DPM) solution was prepared, and the BaTi0 3 powder, together with a dispersant, was input to and dispersed in the DPM solution.
• the resultant solution was mixed with a polysiloxane , so that a final content of the BaTi0 3 powder was 0.3% by weight.
• DPM dipropylene glycol methyl ether
• the mixture solution was printed on the LGP at different printing densities according to areas, with respect to a printing density of 800X800 dpi, by adjusting the size of liquid drops to be 12 pL.
• a printing map having a printing density in a bitmap format was used. After the printing, the printed layer was cured using an inline curing device.
• the transparent LGP and printed layer allowed objects behind the LGP and the printed layer to be visually recognized, thereby providing a transparent illumination device.
• the transmittance and hazing value of the LGP were 87% and 15% when measured using a BYK-Gardner haze meter, available from BYK-Gardner GmbH.

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• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Planar Illumination Modules (AREA)

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• 2018
  • 2018-11-29 KR KR1020180150797A patent/KR20200037718A/ko active Search and Examination
• 2019
  • 2019-09-30 CN CN201980071887.4A patent/CN113056684A/zh active Pending
  • 2019-09-30 EP EP19868723.8A patent/EP3861382A4/de not_active Withdrawn
  • 2019-09-30 JP JP2021518078A patent/JP2022504070A/ja not_active Abandoned
  • 2019-10-01 TW TW108135416A patent/TW202028792A/zh unknown
• 2021
  • 2021-04-04 IL IL282004A patent/IL282004A/en unknown

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