WO2007064133A1 - Light guiding panel using point lights and fabricating method thereof - Google Patents

Light guiding panel using point lights and fabricating method thereof Download PDF

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Publication number
WO2007064133A1
WO2007064133A1 PCT/KR2006/005062 KR2006005062W WO2007064133A1 WO 2007064133 A1 WO2007064133 A1 WO 2007064133A1 KR 2006005062 W KR2006005062 W KR 2006005062W WO 2007064133 A1 WO2007064133 A1 WO 2007064133A1
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WO
WIPO (PCT)
Prior art keywords
light guiding
guiding panel
light
patterns
point lights
Prior art date
Application number
PCT/KR2006/005062
Other languages
French (fr)
Inventor
Chul Jin Hwang
Jong Sun Kim
Young Bae Ko
Young Moo Heo
Original Assignee
Korea Institute Of Industrial Technology
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Filing date
Publication date
Application filed by Korea Institute Of Industrial Technology filed Critical Korea Institute Of Industrial Technology
Publication of WO2007064133A1 publication Critical patent/WO2007064133A1/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
    • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0036—2-D arrangement of prisms, protrusions, indentations or roughened surfaces
    • 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
    • G02B6/0013—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
    • G02B6/003—Lens or lenticular 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
    • 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
    • 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
    • G02B6/0015—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/002—Means for improving the coupling-in of light from the light source into 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, e.g. with collimating, focussing or diverging surfaces
    • 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
    • G02F1/133354—Arrangements for aligning or assembling substrates

Definitions

  • the present invention relates to a light guiding panel using point lights and a fabricating method thereof, more particularly, to a technology employing an edge light method in which the point lights are disposed at both ends of an edge of the light guiding panel, thereby facilely securing uniformity of luminance, wide viewing angle and high luminance of an LCD (Liquid Crystal Display).
  • LCD Liquid Crystal Display
  • a backlight unit is used as an illuminator to uniformly transmit light over the entire of an LCD panel.
  • the backlight unit comprises a backlight source, a reflecting plate, a light guiding panel, a diffusion plate and the like.
  • the light guiding panel functions to uniformly irradiate light from the backlight source on the entire surface of the LCD.
  • the light guiding panel is an injection molded acrylic part for guiding the light to have the same luminance as the backlight unit and to also uniformly illuminate the LCD panel.
  • the light guiding panel is also formed as a plastic molded lens which functions to uniformly transmit the light from a CCFL (Cold
  • Fig. 1 shows a structure of the light guiding panel using point lights.
  • a plurality of point lights 11, 12 and 13 are disposed at a lower side of a light guiding panel 10 with a desired interval, and an LCD is disposed at a rear side thereof.
  • the plurality of point lights 11, 12 and 13 are disposed at the lower side of the light guiding panel 10
  • the luminance is not uniform due to dark portions formed among the point lights.
  • the reliability of product is deteriorated.
  • an optical pattern is formed at the light guiding panel by mechanical working, there is another problem that it is not free to align the pattern and also it is not facile to adjust an optical path.
  • Korean Laid-Open Patent Publication No. 10-2005-0105962 there is disclosed a conventional technology relevant to the structure of light guiding panel, which is entitled Surface light source device, diffusion plate and LCD .
  • the conventional technology is to decrease the difference between a beam spread angle in a direction with wide directivity and a beam spread angle in a direction with narrow directivity by keeping the directivity of light which is substantially vertically emitted from a surface light source device to be small on the whole and then spreading the light in the direction with narrow directivity in the surface light source device using a point source.
  • the surface light source device comprising a light source, a light guide panel for spreading light introduced from the light source in a plane shape and emitting the light thus spread from a light emission face thereof, and a diffusion plate disposed so as to face the light emission face
  • the means for emitting the light is constructed by an uneven pattern having a light deflecting surface, and an inclination angle of the light deflecting face on the plane which is vertical to the light emission face is set to be substantially fixed in the light guide panel, and the directivity of light transmitted through the diffusion plate with respect to vertical incidence has at least one local maximum value within the angular range of 20 degrees at each of both sides of the direction vertical to the diffusion plate.
  • the conventional technology is characterized by decreasing the difference between the beam spread angle in a direction with wide directivity and the beam spread angle in a direction with narrow directivity, whereby the radial luminance unevenness hardly occurs in the surface light source device.
  • the technology of the present invention employing an edge light method and thus facilely securing uniformity of luminance, wide viewing angle and high luminance of an LCD. Disclosure of Invention Technical Problem
  • An object of the present invention to provide to a technology employing an edge light method in which point lights are disposed to be inclined at both ends of a edge of the light guiding panel, thereby preventing dark portions from being formed among the light sources and thus facilely securing uniformity of luminance, wide viewing angle and high luminance of an LCD.
  • the light guiding panel using point lights for LCD comprises point lights which are disposed to be inclined at both sides of an edge of the light guiding panel; and a plurality of optical patterns which are formed at a lower part of the light guiding panel and concentrically arranged around the point lights.
  • the light guiding panel using point lights for LCD comprises point lights which are disposed to be inclined at both sides of an edge of the light guiding panel; and a plurality of optical patterns which are arranged in a scattering region and a mixing region, wherein the scattering region is formed around the points lights and the mixing region is formed between the scattering regions crossed by two point lights.
  • a method of fabricating a light guiding panel comprises a first step of aligning a mask on a substrate on which photoresist is coated, the mask having a first area through which the light can pass and a plurality of second areas through which the light can not pass, and the second areas forming the optical patterns having various dimensions and shapes; a second step of performing a vertical exposing process in which light is radiated from an upper side of the second area to a lower side thereof to form a micro-lens array; a third step of developing the substrate treated by the vertical exposing process to form a photoresist pillar having various dimensions and shapes; a fourth step of forming micro-lens patterns from the photoresist pillar through a reflow process; a fifth step of fabricating an intagliated stamper to intaglio the micro-lens patterns; and a sixth step of forming the light guiding panel having embossed micro-lens patterns by using the int
  • a photoresist pillar in the form of a boomerang (or a serial micro-lens or cone) which has various dimensions and shapes is formed by using the same exposing process, and then a plurality of micro-lens patterns in the form of a crescent moon (or a serial micro-lens or cone) is formed through a reflow process, thereby fabricating a light guiding panel which can secure uniformity of luminance, wide viewing angle and high luminance.
  • FIG. 1 is a view showing a structure of a conventional light guiding panel for an point light
  • FIG. 2 is a view showing a structure of a light guiding panel using point lights according to an embodiment of the present invention
  • FIG. 3 is a flow chart showing a manufacturing process of the light guiding panel using point lights according to an embodiment of the present invention
  • Figs. 4 to 7 are views showing various optical patterns according to embodiments of the present invention
  • Figs. 8 and 9 are view showing examples of arranging the optical patterns according to embodiments of the present invention
  • Fig. 10 is a view showing a change in optical path by a crescent moon-shaped pattern according to embodiments of the present invention.
  • FIG. 2 is a view showing a structure of a light guiding panel using point lights according to the present invention, wherein an edge light method is applied.
  • point lights 21 and 22 are disposed to be inclined at both ends of an edge of a light guiding panel 20 of an LCD.
  • a plurality of optical patterns 23 which are formed at a lower part of the light guiding panel 20 and concentrically arranged around the point lights 21 and 22, thereby securing uniformity of luminance, wide viewing angle and high luminance.
  • the plurality of optical patterns 23 are formed by a semiconductor reflow process used. [31] That is, since the point lights which are disposed to be inclined at both ends of the edge of the light guiding panel 20 can apply an emission angle (90-130 degrees) which is used in an existing LCD, dark portions like in Fig. 1 are not formed. [32] Fig. 3 is a flow chart showing a manufacturing process of the light guiding panel using point lights according to the present invention. [33] First of all, a mask for forming the optical patterns 23 which are concentrically arranged is formed. Herein, the mask is formed with a first area through which the light can pass and a second area through which the light can not pass.
  • the mask is aligned on a semiconductor substrate on which photoresist PR is coated so that the second areas form the optical patterns 23 having various dimensions and shapes (SlO).
  • the mask includes a film mask or a chrome mask according to precision of the pattern. In case of the chrome mask, it is possible to form the patterns having a precision of level 1.
  • a vertical exposing process in which light is radiated from an upper side of the second area to a lower side thereof is performed to form a micro-lens array (S20).
  • various kinds of photoresist can be used in the vertical exposing process according to a thickness thereof.
  • AZ series 9260 can be used as a thick photoresist PR.
  • the vertical exposing process is performed using a spin coater, and the mask is aligned on the substrate, on which the photoresist PR is coated, by an align key. Then the vertical exposing process is performed for a desired time. [37] After that, the semiconductor substrate treated by the vertical exposing process is developed to form the photoresist pillar having various dimensions and shapes (S30). [38] When performing the developing process after the exposing process, AZ series
  • a hot plate or an oven is used in the reflow process to form the micro- lens pattern.
  • heat is applied to the photoresist pillars so that the photoresist pillar is melted.
  • the reflow process is performed at a temperature of 125? for 2 - 10 minutes while the process conditions are changed. The reason why the time difference is occurred in the reflow process is to adjust a curved surface of the optical pattern by controlling the process time.
  • the process time is short, the photoresist PR having a large angle is formed, and if the process time is long, the photoresist PR having a gentle angle is formed.
  • the micro-lens patterns are selectively intagliated or embossed on the light guiding panel by using the intagliated or embossed stamper as a mold.
  • Figs. 4 to 7 are views showing various optical patterns according to embodiments of the present invention.
  • the optical patterns 23 in Fig. 2 can be replaced with the various optical patterns as shown in Figs. 4 to 7.
  • the optical patterns are lastly formed through the reflow process after exposing the photoresist. [50] That is, referring to Figs.
  • the left views show shapes (a-a, c-c, e-e, g-g) of the photoresist patterns (a-a, c-c, e-e, g-g), and the right views show shapes (b-b, d-d, f-f, h-h) of the optical patterns after the reflow process.
  • the optical patterns in Fig. 4 have a serial cone shape having the same sized curved surfaces
  • the optical patterns in Fig. 5 have a serial hemispherical shape having the same sized curved surfaces
  • the optical patterns in Fig. 6 have a serial hemispherical shape having different sized curved surfaces from each other
  • the optical patterns in Fig. 7 have a crescent shape.
  • FIGs. 8 and 9 are view showing examples of arranging the optical patterns according to embodiments of the present invention.
  • the scattering region may be ousted in outer region. If the optical patterns are arranged like in Fig. 9, it is possible to facilely adjust the optical path by the pattern shape as well as the arrangement of the optical patterns.
  • a reference numeral 23a is a first scattering pattern
  • 23b is a second scattering pattern
  • the second scattering pattern has the crescent shape.
  • the present invention since the present invention has three-dimensional optical patterns instead of the conventional simple patterns (e.g., the hemispherical shape), it is possible to facilely and multiply adjust the optical path comparing with the conventional simple patterns shown in Fig. 10

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Light Guides In General And Applications Therefor (AREA)
  • Planar Illumination Modules (AREA)
  • Optical Elements Other Than Lenses (AREA)

Abstract

Disclosed is a light guiding panel using point lights and a fabricating method thereof, more particularly, to a technology employing an edge light method in which the point lights are disposed at both ends of an edge of the light guiding panel, thereby preventing dark portions from being formed among the light sources and thus facilely securing uniformity of luminance, wide viewing angle and high luminance of an LCD. The light guiding panel using point lights for LCD, comprises point lights which are disposed to be inclined at both sides of an edge of the light guiding panel; and a plurality of optical patterns which are formed at a lower part of the light guiding panel and concentrically arranged around the point lights.

Description

Description
LIGHT GUIDING PANEL USING POINT LIGHTS AND FABRICATING METHOD THEREOF
Technical Field
[1] The present invention relates to a light guiding panel using point lights and a fabricating method thereof, more particularly, to a technology employing an edge light method in which the point lights are disposed at both ends of an edge of the light guiding panel, thereby facilely securing uniformity of luminance, wide viewing angle and high luminance of an LCD (Liquid Crystal Display).
Background Art [2] Generally, unlike a cathode ray tube (CRT), a plasma display panel (PDP) and a field emission display (FED), an LCD itself is non-emissive. Thus, it is impossible to use the LCD without a light source. [3] In order to make up for the disadvantage and make it possible to use the LCD even in a dark place, a backlight unit is used as an illuminator to uniformly transmit light over the entire of an LCD panel. [4] The backlight unit comprises a backlight source, a reflecting plate, a light guiding panel, a diffusion plate and the like. Herein, the light guiding panel functions to uniformly irradiate light from the backlight source on the entire surface of the LCD. [5] In other words, the light guiding panel is an injection molded acrylic part for guiding the light to have the same luminance as the backlight unit and to also uniformly illuminate the LCD panel. The light guiding panel is also formed as a plastic molded lens which functions to uniformly transmit the light from a CCFL (Cold
Cathode Fluorescent Lamp) over the entire of the LCD.
[6] Fig. 1 shows a structure of the light guiding panel using point lights.
[7] As shown in Fig. 1, a plurality of point lights 11, 12 and 13 are disposed at a lower side of a light guiding panel 10 with a desired interval, and an LCD is disposed at a rear side thereof. [8] In case that the plurality of point lights 11, 12 and 13 are disposed at the lower side of the light guiding panel 10, there is a problem that the luminance is not uniform due to dark portions formed among the point lights. As the result, the reliability of product is deteriorated. [9] Further, when an optical pattern is formed at the light guiding panel by mechanical working, there is another problem that it is not free to align the pattern and also it is not facile to adjust an optical path. [10] Meanwhile, in Korean Laid-Open Patent Publication No. 10-2005-0105962, there is disclosed a conventional technology relevant to the structure of light guiding panel, which is entitled Surface light source device, diffusion plate and LCD .
[11] The conventional technology is to decrease the difference between a beam spread angle in a direction with wide directivity and a beam spread angle in a direction with narrow directivity by keeping the directivity of light which is substantially vertically emitted from a surface light source device to be small on the whole and then spreading the light in the direction with narrow directivity in the surface light source device using a point source.
[12] In the construction thereof, the surface light source device comprising a light source, a light guide panel for spreading light introduced from the light source in a plane shape and emitting the light thus spread from a light emission face thereof, and a diffusion plate disposed so as to face the light emission face is characterized in that the means for emitting the light is constructed by an uneven pattern having a light deflecting surface, and an inclination angle of the light deflecting face on the plane which is vertical to the light emission face is set to be substantially fixed in the light guide panel, and the directivity of light transmitted through the diffusion plate with respect to vertical incidence has at least one local maximum value within the angular range of 20 degrees at each of both sides of the direction vertical to the diffusion plate.
[13] As described above, the conventional technology is characterized by decreasing the difference between the beam spread angle in a direction with wide directivity and the beam spread angle in a direction with narrow directivity, whereby the radial luminance unevenness hardly occurs in the surface light source device. However, there is a technical difference from the technology of the present invention employing an edge light method and thus facilely securing uniformity of luminance, wide viewing angle and high luminance of an LCD. Disclosure of Invention Technical Problem
[14] An object of the present invention to provide to a technology employing an edge light method in which point lights are disposed to be inclined at both ends of a edge of the light guiding panel, thereby preventing dark portions from being formed among the light sources and thus facilely securing uniformity of luminance, wide viewing angle and high luminance of an LCD. Technical Solution
[15] The light guiding panel using point lights for LCD according to an aspect of the present invention comprises point lights which are disposed to be inclined at both sides of an edge of the light guiding panel; and a plurality of optical patterns which are formed at a lower part of the light guiding panel and concentrically arranged around the point lights.
[16] Further, the light guiding panel using point lights for LCD according to another aspect of the present invention comprises point lights which are disposed to be inclined at both sides of an edge of the light guiding panel; and a plurality of optical patterns which are arranged in a scattering region and a mixing region, wherein the scattering region is formed around the points lights and the mixing region is formed between the scattering regions crossed by two point lights.
[17] Further, a method of fabricating a light guiding panel according to still another aspect of the present invention comprises a first step of aligning a mask on a substrate on which photoresist is coated, the mask having a first area through which the light can pass and a plurality of second areas through which the light can not pass, and the second areas forming the optical patterns having various dimensions and shapes; a second step of performing a vertical exposing process in which light is radiated from an upper side of the second area to a lower side thereof to form a micro-lens array; a third step of developing the substrate treated by the vertical exposing process to form a photoresist pillar having various dimensions and shapes; a fourth step of forming micro-lens patterns from the photoresist pillar through a reflow process; a fifth step of fabricating an intagliated stamper to intaglio the micro-lens patterns; and a sixth step of forming the light guiding panel having embossed micro-lens patterns by using the intagliated stamper as a mold.
Advantageous Effects
[18] According to the embodiments of the present invention, a photoresist pillar in the form of a boomerang (or a serial micro-lens or cone) which has various dimensions and shapes is formed by using the same exposing process, and then a plurality of micro-lens patterns in the form of a crescent moon (or a serial micro-lens or cone) is formed through a reflow process, thereby fabricating a light guiding panel which can secure uniformity of luminance, wide viewing angle and high luminance. Brief Description of the Drawings
[19] The above and other objects, features and advantages of the present invention will become apparent from the following description of embodiments given in conjunction with the accompanying drawings, in which:
[20] Fig. 1 is a view showing a structure of a conventional light guiding panel for an point light;
[21] Fig. 2 is a view showing a structure of a light guiding panel using point lights according to an embodiment of the present invention;
[22] Fig. 3 is a flow chart showing a manufacturing process of the light guiding panel using point lights according to an embodiment of the present invention; [23] Figs. 4 to 7 are views showing various optical patterns according to embodiments of the present invention; [24] Figs. 8 and 9 are view showing examples of arranging the optical patterns according to embodiments of the present invention; and [25] Fig. 10 is a view showing a change in optical path by a crescent moon-shaped pattern according to embodiments of the present invention.
Mode for the Invention [26] Hereinafter, the embodiments of the present invention will be described in detail with reference to accompanying drawings. [27] Fig. 2 is a view showing a structure of a light guiding panel using point lights according to the present invention, wherein an edge light method is applied. [28] As shown in Fig. 2, point lights 21 and 22 are disposed to be inclined at both ends of an edge of a light guiding panel 20 of an LCD. [29] And a plurality of optical patterns 23 which are formed at a lower part of the light guiding panel 20 and concentrically arranged around the point lights 21 and 22, thereby securing uniformity of luminance, wide viewing angle and high luminance. [30] Further, the plurality of optical patterns 23 are formed by a semiconductor reflow process used. [31] That is, since the point lights which are disposed to be inclined at both ends of the edge of the light guiding panel 20 can apply an emission angle (90-130 degrees) which is used in an existing LCD, dark portions like in Fig. 1 are not formed. [32] Fig. 3 is a flow chart showing a manufacturing process of the light guiding panel using point lights according to the present invention. [33] First of all, a mask for forming the optical patterns 23 which are concentrically arranged is formed. Herein, the mask is formed with a first area through which the light can pass and a second area through which the light can not pass. The mask is aligned on a semiconductor substrate on which photoresist PR is coated so that the second areas form the optical patterns 23 having various dimensions and shapes (SlO). [34] The mask includes a film mask or a chrome mask according to precision of the pattern. In case of the chrome mask, it is possible to form the patterns having a precision of level 1. [35] Then, a vertical exposing process in which light is radiated from an upper side of the second area to a lower side thereof is performed to form a micro-lens array (S20). [36] At this time, various kinds of photoresist can be used in the vertical exposing process according to a thickness thereof. AZ series 9260 can be used as a thick photoresist PR. Of course, the vertical exposing process is performed using a spin coater, and the mask is aligned on the substrate, on which the photoresist PR is coated, by an align key. Then the vertical exposing process is performed for a desired time. [37] After that, the semiconductor substrate treated by the vertical exposing process is developed to form the photoresist pillar having various dimensions and shapes (S30). [38] When performing the developing process after the exposing process, AZ series
400k is used as a developer. A part of the photoresist through which the light passes is dissolved in the developing process, and the other part through which the light does not pass is remained. [39] Then, the photoresist pillars are bent by a reflow process to from micro-lens patterns (S40).
[40] At this time, a hot plate or an oven is used in the reflow process to form the micro- lens pattern. In the reflow process, heat is applied to the photoresist pillars so that the photoresist pillar is melted. [41] Preferably, the reflow process is performed at a temperature of 125? for 2 - 10 minutes while the process conditions are changed. The reason why the time difference is occurred in the reflow process is to adjust a curved surface of the optical pattern by controlling the process time. [42] That is, if the process time is short, the photoresist PR having a large angle is formed, and if the process time is long, the photoresist PR having a gentle angle is formed. [43] Therefore, since the curved surface and the height of the photoresist PR can be adjusted after the reflow process, various-shaped micro-lens and micro-lens array can be designed and fabricated. [44] Then, in order to intaglio or emboss the micro-lens patterns, an intagliated stamper or an embossed stamper is fabricated (S50). [45] At this time, the shape of the photoresist having the concentrically arranged pattern is intagliated or embossed on the stamper. [46] The light guiding panel having the intagliated or embossed micro-lens patterns is molded by using the stamper as a mold (S60), and then the fabricating process is completed. [47] Preferably, in the step S50, the micro-lens patterns are selectively intagliated or embossed on the light guiding panel by using the intagliated or embossed stamper as a mold. [48] Figs. 4 to 7 are views showing various optical patterns according to embodiments of the present invention. The optical patterns 23 in Fig. 2 can be replaced with the various optical patterns as shown in Figs. 4 to 7. [49] As described above, the optical patterns are lastly formed through the reflow process after exposing the photoresist. [50] That is, referring to Figs. 4 to 7, the left views show shapes (a-a, c-c, e-e, g-g) of the photoresist patterns (a-a, c-c, e-e, g-g), and the right views show shapes (b-b, d-d, f-f, h-h) of the optical patterns after the reflow process.
[51] The optical patterns in Fig. 4 have a serial cone shape having the same sized curved surfaces, the optical patterns in Fig. 5 have a serial hemispherical shape having the same sized curved surfaces, the optical patterns in Fig. 6 have a serial hemispherical shape having different sized curved surfaces from each other, and the optical patterns in Fig. 7 have a crescent shape.
[52] Figs. 8 and 9 are view showing examples of arranging the optical patterns according to embodiments of the present invention.
[53] Referring to Figs. 8 and 9, in the conventional optical patterns formed by the mechanical working, it is not facile to arrange the patterns. However, according to the present invention, since the arrangement of the patterns becomes free, it is possible to divide and fabricate a scattering region and a mixing region in which a middle portion crossed by two LEDs is mixed by a light source. These regions may be formed in plural.
[54] Further, in arranging the optical patterns, the scattering region may be ousted in outer region. If the optical patterns are arranged like in Fig. 9, it is possible to facilely adjust the optical path by the pattern shape as well as the arrangement of the optical patterns. In Fig. 9, a reference numeral 23a is a first scattering pattern, 23b is a second scattering pattern and the second scattering pattern has the crescent shape.
[55] As described above, since the present invention has three-dimensional optical patterns instead of the conventional simple patterns (e.g., the hemispherical shape), it is possible to facilely and multiply adjust the optical path comparing with the conventional simple patterns shown in Fig. 10
[56] Those skilled in the art will appreciate that the conceptions and specific embodiments disclosed in the foregoing description may be readily utilized as a basis for modifying or designing other embodiments for carrying out the same purposes of the present invention. Those skilled in the art will also appreciate that such equivalent embodiments do not depart from the spirit and scope of the invention as set forth in the appended claims. Industrial Applicability
[57] According to the light guiding panel using point lights and fabricating method thereof of the present invention, it is possible to obtain uniformity of luminance, wide viewing angle and high luminance, and thus it can be applied to the display field.

Claims

Claims
[1] A light guiding panel using point lights for LCD, comprising: point lights which are disposed to be inclined at both sides of an edge of the light guiding panel; and a plurality of optical patterns which are formed at a lower part of the light guiding panel and concentrically arranged around the point lights.
[2] The light guiding panel according to claim 1, wherein the optical patterns are formed through a reflow process after photoresist patterns having different dimensions and shapes are exposed to light.
[3] The light guiding panel according to claim 1 or 2, wherein the optical patterns have a serial cone shape having the same sized curved surfaces, a serial hemispherical shape having the same sized curved surfaces or a serial hemispherical shape having different sized curved surfaces from each other.
[4] The light guiding panel according to claim 1 or 2, wherein the optical patterns have a crescent shape.
[5] A light guiding panel using point lights for LCD, comprising: point lights which are disposed to be inclined at both sides of an edge of the light guiding panel; and a plurality of optical patterns which are arranged in a scattering region and a mixing region, wherein the scattering region is formed around the points lights and the mixing region is formed between the scattering regions crossed by two point lights.
[6] A method of fabricating a light guiding panel, comprising: a first step of aligning a mask on a substrate on which photoresist is coasted, the mask having a first area through which the light can pass and a plurality of second areas through which the light can not pass, and the second areas forming the optical patterns having various dimensions and shapes; a second step of performing a vertical exposing process in which light is radiated from an upper side of the second area to a lower side thereof to form a micro- lens array; a third step of developing the substrate treated by the vertical exposing process to form a photoresist pillar having various dimensions and shapes; a fourth step of forming micro-lens patterns from the photoresist pillar through a reflow process; a fifth step of fabricating an intagliated stamper to intaglio the micro-lens patterns; and a sixth step of forming the light guiding panel having embossed micro-lens patterns by using the intagliated stamper as a mold. [7] The method according to claim 6, wherein the optical patterns have a crescent shape. [8] The method according to claim 6, wherein the reflow process is performed at a temperature of 125? by changing the processing time from 2 minutes until 10 minutes. [9] The method according to claim 6, wherein an embossed stamper to emboss the micro-lens patterns is fabricated in fifth step. [10] The method according to claim 9, wherein the light guiding panel in which the micro-lens patterns are intagliated is formed by using the embossed stamper as a mold.
PCT/KR2006/005062 2005-11-29 2006-11-28 Light guiding panel using point lights and fabricating method thereof WO2007064133A1 (en)

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