WO2007064096A1 - Backlight unit - Google Patents

Backlight unit Download PDF

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Publication number
WO2007064096A1
WO2007064096A1 PCT/KR2006/004788 KR2006004788W WO2007064096A1 WO 2007064096 A1 WO2007064096 A1 WO 2007064096A1 KR 2006004788 W KR2006004788 W KR 2006004788W WO 2007064096 A1 WO2007064096 A1 WO 2007064096A1
Authority
WO
WIPO (PCT)
Prior art keywords
light guide
light
film
backlight unit
guide film
Prior art date
Application number
PCT/KR2006/004788
Other languages
French (fr)
Inventor
Yong-Shig Shim
Original Assignee
Lgs Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Lgs Co., Ltd. filed Critical Lgs Co., Ltd.
Publication of WO2007064096A1 publication Critical patent/WO2007064096A1/en

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—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
    • G02F1/133615—Edge-illuminating devices, i.e. illuminating from the side
    • 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
    • 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
    • G02F1/133524—Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2457/00—Electrical equipment
    • B32B2457/20—Displays, e.g. liquid crystal displays, plasma displays
    • B32B2457/202—LCD, i.e. liquid crystal displays
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2115/00—Light-generating elements of semiconductor light sources
    • F21Y2115/10—Light-emitting diodes [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
    • G02B6/0013—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
    • G02B6/0028—Light guide, e.g. taper
    • 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
    • G02B6/0051—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
    • 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
    • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
    • G02F2201/38—Anti-reflection arrangements
    • 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
    • G02F2202/00—Materials and properties
    • G02F2202/28—Adhesive materials or arrangements

Definitions

  • the present invention relates to a backlight unit, and more particularly, to a backlight unit which has an improved configuration so that the thickness and the manufacturing cost thereof can be significantly decreased.
  • One of the technologies which contribute to the slimness of the display devices is a side illumination type backlight unit.
  • the basic configuration of a conventional side illumination type backlight unit 101 and a display device 201 having the same includes a light guide panel 110 which has a light source 121 on one side thereof, and at least one optical film 140 which collects and refracts to a panel 103 the light rays transmitted from the light guide panel 110.
  • the thickness of the light guide panel corresponds to, or is greater than, the size of the light source.
  • the optical films such as the light guide panel 110, the optical film
  • the overall thickness of the backlight unit 101 increases due to the existence of tolerance in assembling the parts. Also, because the assembly process is complicated, the productivity is deteriorated. Moreover, a defect such as damage to an optical structure can occur due to the contact between the respective optical parts.
  • the present invention has been made in an effort to solve the problems occurring in the related art, and an object of the present invention is to provide a backlight unit the thickness of which can be remarkably decreased, the manufacturing cost of which can be reduced, and the productivity of which can be improved, and in which the occurrence of defects is prevented.
  • a backlight unit comprising a light-transmissive light guide film having the shape of a thin film; a light source section arranged to be brought into contact with the surface of at least one region of the light guide film and having a light source and a light guide element for guiding light from the light source to the light guide film; and at least one optical film integrally stacked on the output-side surface of the light guide film by an adhesive material having a refractive index which is different from that of the optical film.
  • the light source comprises an
  • the light source is coupled to a plurality of regions of the light guide element through insertion.
  • the light source section is integrally attached to the light guide film.
  • a plurality of light source sections is arranged on the peripheral region of the light guide film.
  • an optical pattern for collecting and refracting light in a light output direction is formed on the surface of the optical film, which faces the adhesive material and the light guide film.
  • a reflection panel comprising a thin film is attached to at least the surface of the light guide film that is opposite the output-side surface of the light guide film.
  • a diffusion or scattering constituent for diffusing or scattering light is contained in the adhesive material.
  • FIG. 1 is a side view schematically illustrating a conventional backlight unit
  • FIG. 2 is a side view schematically illustrating a backlight unit in accordance with an embodiment of the present invention
  • FIGs. 3 through 6 are side views illustrating backlight units according to variations of the present invention.
  • FIG. 7 is a side view schematically illustrating a display device having the backlight unit according to the present invention.
  • FIG. 2 is a side view schematically illustrating a backlight unit in accordance with an embodiment of the present invention.
  • a backlight unit 1 according to the present invention includes a light guide panel 10, at least one light source section 20 for emitting light into the light guide panel 10, and at least one optical film 40 integrally stacked on the output-side surface of the light guide film 10 by an adhesive material 30.
  • the light guide film 10 is formed in the shape of a thin film using any one of polycarbonate, PVC, PP, PE, PET, and acryl-based polymer as light-transmissive materials.
  • An optical pattern structure 11, a diffusion structure, a scattering structure, etc. can be included in the light guide film 10 so that incident light can be output after undergoing optical actions such as refraction, condensation, diffusion, scattering, and so forth.
  • a reflective sheet 13 is provided on the surface (the lower surface in the drawing) of the light guide film 10 that is opposite the output-side surface of the light guide film 10.
  • the reflective sheet 13 reflects incident light upwards into the light guide film 10 and thereby prevents an optical loss from occurring.
  • the reflective sheet 13 may comprise a thin metal plate which has excellent reflection efficiency, or may be embodied in the shape of a sheet which has a reflective paint applied thereto.
  • the light source section 20 includes a light source 21 for emitting light, and a light guide element 23 for guiding the light emitted from the light source 21 to the light guide film 10.
  • the light source 21 comprises a lamp or an LED depending upon the kind of display device 60, and is coupled to the light guide element 23 through insertion. At this time, it is preferred that the light source 21 comprise an LED in order to save power and realize the miniaturization of the backlight unit 1 and the display device 60. Also, as shown in FIGs. 2 and 3, the light source 21 can be inserted into the side surface or the lower surface of the light guide element 23 depending upon the amount of light that is desired. Alternatively, as shown in FIG. 4, a plurality of light sources 21 can be inserted into the side surface and the lower surface of the light guide element 23.
  • the light guide element 23 is formed of a light-transmissive material and is installed so as to be in contact with the surface of one region of the light guide film 10. While not shown in the drawings, a diffraction grating structure for diffracting light into the light guide film 10 may be formed in the light guide element 23 so that the light rays emitted from the light source 21 can be reliably guided into the light guide film 10, or a guide pattern (not shown), such as one of various refraction patterns, may be formed in the light guide panel 23 so that light can be deflected into the light guide film 10.
  • the light source section 20 is integrally attached to the surface of one region of the light guide film 10 so as to be integrated with the light guide film 10, the miniaturization of the backlight unit 1 and the display device 60 can be facilitated. As shown in FIGs. 2 through 4, only one light source section 20 can be arranged on one region of the light guide film 10, or, depending upon the size of the display device 60, as shown in FIG. 5, a pair of light source sections 20 can be provided to both opposing side regions of the light guide film 10. Further, while not shown in the drawings, a plurality of light source sections 20 can be arranged on the peripheral region of the light guide film 10 at regular intervals or over the entire surface of the peripheral region of the light guide film 10.
  • the optical film 40 is integrally stacked on the output-side surface of the light guide film 10 using an adhesive material 30 such as UV resin, etc. which has a refractive index different from that of the optical film 40.
  • An optical pattern 41 is formed on one surface of the optical film 40 so as to collect and refract the light output from the light guide film 10 in the light output direction.
  • the optical pattern 41 can be formed to have an optical structure capable of effectively collecting and refracting light in the light output direction, such as a configuration in which a plurality of triangular sectional shapes or rounded sectional shapes are arranged in a line or in a configuration such as an array of a plurality of lenses.
  • the optical film 40 can be stacked on the light guide film 10 in an arrangement in which the optical pattern 41 faces the light output direction, it is preferred that the optical film 40 be stacked on the light guide film 10 in the shape in which the optical pattern 41 faces the light guide film 10. This is to ensure that the optical pattern 41 of the optical film 40 is protected by the adhesive material 30, and thereby the optical parts are prevented from being damaged due to contact with each other. At this time, reliable refraction of the light is realized due to the difference in refractive index between the optical film 40 and the adhesive material 30.
  • the thickness of the backlight unit 1 is significantly decreased, as can be readily seen in FIG. 7, the thickness of the display device 60 is also significantly decreased.
  • the optical driving of the display device 60 having the backlight unit 1 is implemented as described below.
  • non-directional light emitted from the light source 21 is incident through the surface of one region of the light guide film 10 and is guided by the light guide element 23.
  • the light, which is incident through the light guide film 10 is transmitted toward the other end of the light guide film 10.
  • the light rays, directed downward with respect to the light guide film 10 are reflected by the reflective sheet 13 toward the output side of the light guide film 10, whereby the loss of light is minimized.
  • the light output through the output-side surface of the light guide film 10 is collected and refracted by the optical film 40 which is stacked on the light guide film 10 by the adhesive material 30, and is transmitted to a panel 63, so that an image can be displayed on the panel 63.
  • FIG. 6 is a side view illustrating a backlight unit according to a variation of the present invention.
  • the backlight unit 1 according to this variation has substantially the same construction as the backlight units of FIGs. 2 through 6, except that a diffusion constituent 51 or a scattering constituent 53 for diffusing or scattering light is contained in the adhesive material 30.
  • the diffusion constituent 51 or the scattering constituent 53 may comprise a predetermined optical diffusion or scattering structure or a diffusion or scattering agent capable of diffusing or scattering light.
  • a light guide film is constructed in the shape of a thin film, the light rays emitted from the light source are transmitted to the light guide film by the light guide element, and the optical film is integrally bonded to and stacked on the output side of the light guide film.
  • the light guide film is formed of a thin film material, the manufacturing cost can be significantly reduced compared to the conventional light guide panel formed using costly molds.

Abstract

A backlight unit comprises a light-transmissive light guide film having the shape of a thin film; a light source section arranged to be brought into contact with the surface of at least one region of the light guide film and having a light source and a light guide element for guiding light from the light source to the light guide film; and at least one optical film integrally stacked on an output-side surface of the light guide film by an adhesive material having a refractive index which is different from that of the optical film.

Description

Description BACKLIGHT UNIT
Technical Field
[1] The present invention relates to a backlight unit, and more particularly, to a backlight unit which has an improved configuration so that the thickness and the manufacturing cost thereof can be significantly decreased.
[2]
Background Art
[3] As is well known in the art, in a display device such as an LCD monitor, a desired image is displayed on a panel by the medium of light transmitted to the panel from a backlight unit. Recently, with the development of technology, display devices have rapidly become slimmer.
[4] One of the technologies which contribute to the slimness of the display devices is a side illumination type backlight unit.
[5] Referring to FIG. 1, the basic configuration of a conventional side illumination type backlight unit 101 and a display device 201 having the same includes a light guide panel 110 which has a light source 121 on one side thereof, and at least one optical film 140 which collects and refracts to a panel 103 the light rays transmitted from the light guide panel 110.
[6] In this conventional backlight unit 101, after the light rays have been emitted from the light source 121 through one end of the light guide panel 110, while traveling toward the other end of the light guide panel 110, the light rays are upwardly output toward the optical film 140. At this time, since the light rays are non-directionally incident on the light guide panel 110, some of the light rays are output in an upward direction. The remainder of the light rays are output in other directions, for example, in a downward direction, they are reflected by the reflective sheet 113 provided under the light guide panel 110, so that most of the light rays are output in the upward direction.
[7] However, in the conventional backlight unit 101, since the light source 121 is located on one side of the light guide panel 110, in order to ensure that the light rays from the light source 121 are incident on the light guide panel 110 without loss, the plane of incidence at the end of the light guide panel 110 that faces the light source 121 must have a relatively large area. In general, in a side illumination type backlight unit, the thickness of the light guide panel corresponds to, or is greater than, the size of the light source.
[8] Due to this fact, since the light guide panel 110 cannot but be formed to have a substantial thickness, limitations exist in reducing the thickness of the backlight unit 101 and the display device 201 having the same, and the manufacturing cost thus increases.
[9] Also, in the conventional side illumination type backlight unit, a problem is caused in that the light guide panel 110 is manufactured through injection molding, which uses costly molds.
[10] Further, because the optical parts, such as the light guide panel 110, the optical film
140, and so on, are separately provided, the overall thickness of the backlight unit 101 increases due to the existence of tolerance in assembling the parts. Also, because the assembly process is complicated, the productivity is deteriorated. Moreover, a defect such as damage to an optical structure can occur due to the contact between the respective optical parts.
[H]
Disclosure of Invention Technical Problem
[12] Accordingly, the present invention has been made in an effort to solve the problems occurring in the related art, and an object of the present invention is to provide a backlight unit the thickness of which can be remarkably decreased, the manufacturing cost of which can be reduced, and the productivity of which can be improved, and in which the occurrence of defects is prevented.
[13]
Technical Solution
[14] In order to achieve the above object, according to one aspect of the present invention, there is provided a backlight unit comprising a light-transmissive light guide film having the shape of a thin film; a light source section arranged to be brought into contact with the surface of at least one region of the light guide film and having a light source and a light guide element for guiding light from the light source to the light guide film; and at least one optical film integrally stacked on the output-side surface of the light guide film by an adhesive material having a refractive index which is different from that of the optical film.
[15] According to another aspect of the present invention, the light source comprises an
LED and is coupled to the light guide element by being inserted therein.
[16] According to another aspect of the present invention, the light source is coupled to a plurality of regions of the light guide element through insertion.
[17] According to another aspect of the present invention, the light source section is integrally attached to the light guide film.
[18] According to another aspect of the present invention, a plurality of light source sections is arranged on the peripheral region of the light guide film. [19] According to another aspect of the present invention, an optical pattern for collecting and refracting light in a light output direction is formed on the surface of the optical film, which faces the adhesive material and the light guide film.
[20] According to still another aspect of the present invention, a reflection panel comprising a thin film is attached to at least the surface of the light guide film that is opposite the output-side surface of the light guide film.
[21] According to a still further aspect of the present invention, a diffusion or scattering constituent for diffusing or scattering light is contained in the adhesive material.
[22]
Advantageous Effects
[23] As is apparent from the above description, in the present invention, it is possible to provide a backlight unit and a display device having the same wherein the thickness thereof can be remarkably decreased, the manufacturing cost can be reduced, productivity is improved, and the occurrence of defects is prevented.
[24]
Brief Description of the Drawings
[25] The above objects and other features and advantages of the present invention will become more apparent after a reading of the following detailed description taken in conjunction with the drawings, in which:
[26] FIG. 1 is a side view schematically illustrating a conventional backlight unit;
[27] FIG. 2 is a side view schematically illustrating a backlight unit in accordance with an embodiment of the present invention;
[28] FIGs. 3 through 6 are side views illustrating backlight units according to variations of the present invention; and
[29] FIG. 7 is a side view schematically illustrating a display device having the backlight unit according to the present invention.
[30]
Best Mode for Carrying Out the Invention
[31] Reference will now be made in greater detail to a preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings and the description to refer to the same or like parts.
[32] FIG. 2 is a side view schematically illustrating a backlight unit in accordance with an embodiment of the present invention. Referring to FIG. 2, a backlight unit 1 according to the present invention includes a light guide panel 10, at least one light source section 20 for emitting light into the light guide panel 10, and at least one optical film 40 integrally stacked on the output-side surface of the light guide film 10 by an adhesive material 30.
[33] The light guide film 10 is formed in the shape of a thin film using any one of polycarbonate, PVC, PP, PE, PET, and acryl-based polymer as light-transmissive materials. An optical pattern structure 11, a diffusion structure, a scattering structure, etc. can be included in the light guide film 10 so that incident light can be output after undergoing optical actions such as refraction, condensation, diffusion, scattering, and so forth.
[34] A reflective sheet 13 is provided on the surface (the lower surface in the drawing) of the light guide film 10 that is opposite the output-side surface of the light guide film 10. The reflective sheet 13 reflects incident light upwards into the light guide film 10 and thereby prevents an optical loss from occurring. The reflective sheet 13 may comprise a thin metal plate which has excellent reflection efficiency, or may be embodied in the shape of a sheet which has a reflective paint applied thereto. Here, it is preferred in the interests of slimness that the reflective sheet 13 be integrally attached by an adhesive material 30 to the surface of the light guide film 10 that is opposite the output-side surface.
[35] The light source section 20 includes a light source 21 for emitting light, and a light guide element 23 for guiding the light emitted from the light source 21 to the light guide film 10.
[36] The light source 21 comprises a lamp or an LED depending upon the kind of display device 60, and is coupled to the light guide element 23 through insertion. At this time, it is preferred that the light source 21 comprise an LED in order to save power and realize the miniaturization of the backlight unit 1 and the display device 60. Also, as shown in FIGs. 2 and 3, the light source 21 can be inserted into the side surface or the lower surface of the light guide element 23 depending upon the amount of light that is desired. Alternatively, as shown in FIG. 4, a plurality of light sources 21 can be inserted into the side surface and the lower surface of the light guide element 23.
[37] The light guide element 23 is formed of a light-transmissive material and is installed so as to be in contact with the surface of one region of the light guide film 10. While not shown in the drawings, a diffraction grating structure for diffracting light into the light guide film 10 may be formed in the light guide element 23 so that the light rays emitted from the light source 21 can be reliably guided into the light guide film 10, or a guide pattern (not shown), such as one of various refraction patterns, may be formed in the light guide panel 23 so that light can be deflected into the light guide film 10.
[38] Because the light source section 20 is integrally attached to the surface of one region of the light guide film 10 so as to be integrated with the light guide film 10, the miniaturization of the backlight unit 1 and the display device 60 can be facilitated. As shown in FIGs. 2 through 4, only one light source section 20 can be arranged on one region of the light guide film 10, or, depending upon the size of the display device 60, as shown in FIG. 5, a pair of light source sections 20 can be provided to both opposing side regions of the light guide film 10. Further, while not shown in the drawings, a plurality of light source sections 20 can be arranged on the peripheral region of the light guide film 10 at regular intervals or over the entire surface of the peripheral region of the light guide film 10.
[39] The optical film 40 is integrally stacked on the output-side surface of the light guide film 10 using an adhesive material 30 such as UV resin, etc. which has a refractive index different from that of the optical film 40. An optical pattern 41 is formed on one surface of the optical film 40 so as to collect and refract the light output from the light guide film 10 in the light output direction. The optical pattern 41 can be formed to have an optical structure capable of effectively collecting and refracting light in the light output direction, such as a configuration in which a plurality of triangular sectional shapes or rounded sectional shapes are arranged in a line or in a configuration such as an array of a plurality of lenses.
[40] Here, while the optical film 40 can be stacked on the light guide film 10 in an arrangement in which the optical pattern 41 faces the light output direction, it is preferred that the optical film 40 be stacked on the light guide film 10 in the shape in which the optical pattern 41 faces the light guide film 10. This is to ensure that the optical pattern 41 of the optical film 40 is protected by the adhesive material 30, and thereby the optical parts are prevented from being damaged due to contact with each other. At this time, reliable refraction of the light is realized due to the difference in refractive index between the optical film 40 and the adhesive material 30.
[41] In the backlight unit 1 according to the present invention, constructed as mentioned above, since the thickness of the backlight unit 1 is significantly decreased, as can be readily seen in FIG. 7, the thickness of the display device 60 is also significantly decreased. The optical driving of the display device 60 having the backlight unit 1 is implemented as described below.
[42] First, non-directional light emitted from the light source 21 is incident through the surface of one region of the light guide film 10 and is guided by the light guide element 23. The light, which is incident through the light guide film 10, is transmitted toward the other end of the light guide film 10. At this time, the light rays, directed downward with respect to the light guide film 10, are reflected by the reflective sheet 13 toward the output side of the light guide film 10, whereby the loss of light is minimized.
[43] Then, the light output through the output-side surface of the light guide film 10 is collected and refracted by the optical film 40 which is stacked on the light guide film 10 by the adhesive material 30, and is transmitted to a panel 63, so that an image can be displayed on the panel 63.
[44] FIG. 6 is a side view illustrating a backlight unit according to a variation of the present invention. Referring to FIG. 6, the backlight unit 1 according to this variation has substantially the same construction as the backlight units of FIGs. 2 through 6, except that a diffusion constituent 51 or a scattering constituent 53 for diffusing or scattering light is contained in the adhesive material 30.
[45] Here, the diffusion constituent 51 or the scattering constituent 53 may comprise a predetermined optical diffusion or scattering structure or a diffusion or scattering agent capable of diffusing or scattering light.
[46] Due to this fact, it is possible to effectively diffuse or scatter light without using an additional part such as a diffusion sheet or a scattering sheet, and thereby, it is possible to prevent the thickness of the backlight unit 1 from being increased due to the addition of the part.
[47] In the backlight unit according to the present invention, a light guide film is constructed in the shape of a thin film, the light rays emitted from the light source are transmitted to the light guide film by the light guide element, and the optical film is integrally bonded to and stacked on the output side of the light guide film. As a consequence, the thicknesses of the backlight unit and the display device having the same are significantly decreased.
[48] Also, since the light guide film is formed of a thin film material, the manufacturing cost can be significantly reduced compared to the conventional light guide panel formed using costly molds.
[49] Further, because the assembly process is simplified, productivity is improved, and because contact between respective optical parts is prevented during the assembly process, defects such as damage to the optical pattern of the optical film can be avoided.
[50]
Industrial Applicability
[51] As is apparent from the above description, in the present invention, it is possible to provide a backlight unit and a display device having the same wherein the thickness thereof can be remarkably decreased, the manufacturing cost can be reduced, p ro- ductivity is improved, and the occurrence of defects is prevented.
[52] Although a preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. [53] [54]

Claims

Claims
[ 1 ] A backlight unit comprising: a light-transmissive light guide film having the shape of a thin film; a light source section arranged to be brought into contact with a surface of at least one region of the light guide film and having a light source and a light guide element for guiding light from the light source to the light guide film; and at least one optical film integrally stacked on an output-side surface of the light guide film by an adhesive material having a refractive index which is different from that of the optical film. [2] The backlight unit according to claim 1, wherein the light source comprises an
LED and is coupled to the light guide element through insertion. [3] The backlight unit according to claim 2, wherein the light source is coupled to a plurality of regions of the light guide element through insertion. [4] The backlight unit according to claim 1, wherein the light source section is integrally attached to the light guide film. [5] The backlight unit according to any one of the preceding claims 1 to 4, wherein a plurality of light source sections is arranged on a peripheral region of the light guide film. [6] The backlight unit according to claim 5, wherein an optical pattern for collecting and refracting light in a light output direction is formed on a surface of the optical film that faces the adhesive material and the light guide film. [7] The backlight unit according to claim 6, wherein a reflection panel comprising a thin film is attached at least to a surface of the light guide film that is opposite the output-side surface of the light guide film. [8] The backlight unit according to claims 6 or 7, wherein a diffusion or scattering constituent for diffusing or scattering light is contained in the adhesive material.
PCT/KR2006/004788 2005-11-29 2006-11-15 Backlight unit WO2007064096A1 (en)

Applications Claiming Priority (2)

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KR10-2005-0114654 2005-11-29
KR1020050114654A KR100613839B1 (en) 2005-11-29 2005-11-29 Back light unit

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