KR20140037447A - Light guide panel - Google Patents

Light guide panel Download PDF

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Publication number
KR20140037447A
KR20140037447A KR1020120103497A KR20120103497A KR20140037447A KR 20140037447 A KR20140037447 A KR 20140037447A KR 1020120103497 A KR1020120103497 A KR 1020120103497A KR 20120103497 A KR20120103497 A KR 20120103497A KR 20140037447 A KR20140037447 A KR 20140037447A
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KR
South Korea
Prior art keywords
light
light incident
guide plate
light guide
incident surface
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KR1020120103497A
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Korean (ko)
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KR102009855B1 (en
Inventor
박화서
김동율
이진영
Original Assignee
엘지디스플레이 주식회사
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Priority to KR1020120103497A priority Critical patent/KR102009855B1/en
Publication of KR20140037447A publication Critical patent/KR20140037447A/en
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    • 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
    • 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
    • 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
    • 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

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

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide plate, and in particular, a pattern is not formed on the bottom surface of the light guide plate. And it is a technical problem to provide a liquid crystal display device using the same. To this end, the light guide plate according to the present invention includes a light incident surface on which light is incident; A lower surface inclined in a curved shape to reflect light incident through the light incident surface; A light incident surface facing the light incident surface with the lower surface interposed therebetween; And an upper surface in the form of a plate facing the lower surface with the light incident surface and the incoming light incident surface therebetween.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a light guide plate, and more particularly, to a light guide plate applied to a liquid crystal display device.

The liquid crystal display device displays an image using a thin film transistor. The liquid crystal display device is applied not only to display devices in portable information devices, office equipment, computers, etc., but also to televisions.

Since the liquid crystal display is not a self-luminous element, a backlight unit is provided under the liquid crystal panel to display an image using light emitted from the backlight unit.

The backlight unit may be classified into an edge type and a direct type according to the arrangement of light sources.

1 is an exemplary view showing a conventional photometric backlight unit. 2 and 3 are exemplary views showing various forms of a light guide plate applied to a conventional photometric backlight unit, and FIG. 2 shows a flat light guide plate formed in a flat plate shape, and FIG. 3 shows an inferior bottom surface thereof. The inclined light guide plate is shown.

As shown in FIG. 1, in the photometric backlight unit, a light source 12 is disposed on a side surface of a light guide plate 11 provided below a panel (not shown), and the photometric light emitted from the light source through the light guide plate is converted into surface light. By irradiating the panel, there is an advantage that the liquid crystal display device can be made slim.

Various types of optical sheets 13 may be disposed on the top of the light guide plate.

As the light source 12 of the backlight unit, an external electrode fluorescent lamp (EEFL), a cold cathode fluorescent lamp (CCFL), a light emitting diode (LED), and the like may be used. Recently, a light emitting diode (LED) has been widely used.

The light guide plate 11 converts the point light generated from the light source 12, in particular, LED into surface light and transmits the light to the panel. As shown in FIG. 2, the light guide plate 11 may be formed in a flat plate shape. It may be formed in an inclined form.

As shown in (b) of FIG. 2, the flat light guide plate modifies the angle of refraction of light incident into the light guide plate by using a plurality of patterns formed on the lower surface of the light guide plate and outputs the light to the outside of the light guide plate.

In this case, a total reflection principle (Snell's law) using a difference in refractive index between PMMA (polymethylmethacrylate) and air, which forms the light guide plate, is used.

In particular, the flat light guide plate controls the distribution of light output in the panel direction by adjusting the density ratio of the pattern as described above.

A flat light guide plate having a plurality of patterns formed thereon is manufactured by adjusting the density ratio of the patterns based on simulation results.

However, the flat light guide plate as shown in FIG. 2 has the following problems.

First, a pattern is formed based on simulation. However, since the size of the pattern is not constant, the mold is first processed to check the light distribution, and the mold is scraped off and then subjected to the second process to confirm the light distribution, and then the light guide plate is manufactured using the same. Therefore, the cost and time for manufacturing the light guide plate are high.

Second, due to the nature of the flat structure, as shown in FIG. Because light is incident at a greater angle, it is continuously refracted at the top and bottom surfaces and eventually counts toward the incoming light plane. Therefore, light loss of the light guide plate is generated and the efficiency of the light guide plate is lowered.

Third, the intervals or densities of the patterns are regularly arranged according to the thickness of the light guide plate. Accordingly, as shown in FIG. 2C, dot reflection and moire may be generated.

That is, since the light guide plate is made thin and the number of refractions of the light incident on the light guide plate is increased, light distribution is required to be adjusted, so that the pitch between patterns regularly arranged in the light guide plate is getting farther away or the density is reduced. At this time, dot reflection and moire are generated due to the difference in pitch and density of the regular pattern.

Also in the case of the inclined light guide plate, as shown in FIG. 3, light is reflected in the direction of the liquid crystal panel using a plurality of patterns and reflecting plates formed on the lower surface of the light guide plate. Therefore, the inclined light guide plate also has the same problems as the flat light guide plate described above.

That is, the inclined light guide plate also takes a lot of manufacturing cost and time, and causes a loss due to the light 16 that is counted toward the incoming light receiving surface, and dot reflection and moiré may be generated. In addition, since the inclined light guide plate becomes thinner in the light incident surface direction, it is difficult to form a pattern in the light incident surface direction. Therefore, the inclined light guide plate is more difficult to control the refraction and reflection of light by the pattern than the flat light guide plate.

The present invention has been proposed to solve the above-mentioned problems, and the pattern is not formed on the lower surface, and the lower surface is formed as a curved inclined surface to reflect light emitted below a critical angle with respect to the light incident surface to emit light. It is an object of the present invention to provide a light guide plate and a liquid crystal display device using the same.

The light guide plate according to the present invention for achieving the above technical problem, the light incident surface is incident light; A lower surface inclined in a curved shape to reflect light incident through the light incident surface; A light incident surface facing the light incident surface with the lower surface interposed therebetween; And an upper surface in the form of a plate facing the lower surface with the light incident surface and the incoming light incident surface therebetween.

According to an aspect of the present invention, a liquid crystal display device includes: a guide panel; The light guide plate disposed on the guide panel; A liquid crystal panel disposed on an upper end of the light guide plate to output an image; And a light source unit disposed at a side surface of the light guide plate to allow light to enter the light incident surface of the light guide plate.

According to the present invention, a pattern is not formed on the lower surface, and the lower surface is formed as a curved inclined surface, so that light incident at a critical angle or less with respect to the incident surface can be reflected and emitted to the outside. That is, the present invention is advantageous in a thin structure because it can maximize the efficiency by emitting most of the light received from the light source.

In addition, the present invention can remove the pattern of the lower surface of the light guide plate, while easily distributing the light source, it is possible to reduce the time and cost to reduce the material cost.

1 is an exemplary view showing a conventional photometric backlight unit.
2 and 3 are exemplary views showing various forms of a light guide plate applied to a conventional photometric type backlight unit.
5 is an exemplary view showing the overall shape of a light guide plate according to the present invention.
6 is an exemplary view for explaining a phenomenon that the light is refracted and reflected in the light guide plate according to the present invention.
7 is an exemplary view comparing light distribution states of a light guide plate according to the present invention and a conventional light guide plate.
8 is an exemplary view showing a state in which a pattern is formed on the upper surface of the light guide plate according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is an exemplary view showing a cross section of a liquid crystal display according to the present invention.

As shown in FIG. 4, the liquid crystal display according to the present invention includes a cover bottom 110, a light guide plate 120 disposed on the cover bottom, and a liquid crystal panel 150 disposed on the top of the light guide plate to output an image. ), A light source unit 170 disposed on the side of the light guide plate on the cover bottom to guide the light to the side of the light guide plate, a guide panel 140 for guiding the light guide plate and supporting the panel, and surrounding the upper edge of the upper surface of the liquid crystal panel. A case top 160 fastened to the bottom, an optical sheet 130 composed of a plurality of optical films, and a reflecting plate inserted between the light guide plate and the cover bottom to reflect light traveling to the lower end of the light guide plate to the upper end of the light guide plate ( 121).

First, the cover bottom 110 is fastened to the case top 160 to embed the liquid crystal panel 150 and the above components between the case top 160 and the cover bottom 110. Do this.

The reflecting plate 121 is stacked at the bottom end of the cover bottom 110, and the light guide plate 120, the optical sheet unit 130, and the liquid crystal panel 150 according to the present invention are sequentially disposed on the reflecting plate. Are stacked.

In particular, the present invention relates to a metering type liquid crystal display device, wherein the light source unit 170 on which the light source 171 is mounted is mounted on one side surface of the cover bottom 110.

That is, the light source unit 170 may include any one of four side surfaces except for an upper surface and a lower surface of the light guide plate 120 adjacent to the optical sheet unit 130 and the reflecting plate 121, and the cover bottom. It is mounted between the sides of the 110.

As described above, the cover bottom 110 is engaged with the case top 160 to perform the function of embedding the components as described above.

Next, the liquid crystal panel 150 drives the liquid crystal injected between the array substrate and the color filter substrate to a voltage applied to the array substrate, thereby controlling the light emitted from the light source 171 mounted on the light source unit 170. The video is output by controlling the amount of transmission.

Next, the light source unit 170 is for receiving light into the liquid crystal panel 150 through the light guide plate 120. As a light source that emits light, an external electrode fluorescent lamp (EEFL) and a cold cathode fluorescent lamp are used. (CCFL), a light emitting diode (LED), and the like may be used. Hereinafter, a light emitting diode (LED) is described as an example of the light source 171 for convenience of description.

That is, the light source unit 170 includes an LED 171 used as a light source, a substrate 172 supporting a LED and a circuit for driving the LED, and a support 173 on which the substrate is mounted. Can be. Here, the substrate 172 may be formed to perform the function of the support 173.

Next, the guide panel 140 guides the light guide plate 120 and supports the liquid crystal panel 150.

That is, the guide panel 140 is formed in a rectangular frame, so that the reflecting plate 121, the light guide plate 120, and the optical sheet unit 130 disposed therein are formed on side surfaces of the guide panel 140. Guided and fixed to a fixed position.

Next, the case top 160 is fastened to the cover bottom to perform the function of embedding the liquid crystal panel and the above components between the case top and the cover bottom.

The case top 160 surrounds a flat outer surface of the liquid crystal panel, and light emitted from the liquid crystal panel is output to the outside through an open central portion of the case top.

In recent years, a liquid crystal display equipped with a borderless type case top is developed and sold in order to satisfy the consumer's desire in terms of design. In the borderless liquid crystal display device, there may be a form manufactured such that there is no step in the plane of the liquid crystal panel and the case top 160, or the width of the case top exposed to the plane of the liquid crystal panel is very large. There may be a narrowly formed form.

Next, the optical sheet unit 130 is for diffusing light passing through the light guide plate 120 or allowing light passing through the light guide plate 120 to be incident on the liquid crystal panel. It may be variously formed, including a sheet (diffuser sheet), a prism sheet (prism sheet) and the like. In addition, although not shown in the drawings, a polarizing film may be attached to the plane and the bottom of the liquid crystal panel 150. That is, the polarizing film is attached to the plane or the bottom of the liquid crystal panel and performs a function of passing only components in a specific direction among the components of the light transmitted through the light guide plate.

Next, the reflecting plate 121 is attached to the lower surface of the light guide plate 120, and performs a function of reflecting light emitted from the LED to the lower direction of the light guide plate in the direction of the liquid crystal panel of the upper light guide plate 120. do. That is, the light emitted from the LED mounted on the light source unit 170 and introduced into the light guide plate 120 is refracted by the light guide plate and reflected in the direction of the liquid crystal panel, but the bottom surface of the light guide plate 120 is not reflected. There may also be light leaking to the outside through the bar, the reflector 121 performs the function of reflecting the light back to the direction of the liquid crystal panel.

Finally, the LGP 120 according to the present invention performs a function of scattering and reflecting light emitted from the LED and transmitting the light guide panel to the liquid crystal panel 150 disposed on the top of the LGP. do.

The light guide plate 120 may be formed of a material such as plastic or resin, such as polymethylmethacrylate (PMMA).

The upper surface of the light guide plate 120 that is in contact with the liquid crystal panel is formed in a plane parallel to the plane of the liquid crystal panel, and the lower surface opposite to the upper surface is formed in a curved shape inclined with respect to the upper surface.

In addition, a pattern is not formed on the bottom surface of the light guide plate 120.

The structure and function of the light guide plate 120 according to the present invention will be described in detail with reference to FIGS. 5 to 8 below.

5 is an exemplary view showing the overall shape of the light guide plate according to the present invention, Figure 6 is an exemplary view for explaining the phenomenon that the light is refracted and reflected in the light guide plate according to the present invention, Figure 7 is a light guide plate according to the present invention and FIG. 8 is an exemplary view comparing light distribution states of a conventional light guide plate, and FIG. 8 is an exemplary view showing a state in which a pattern is formed on an upper surface of the light guide plate according to the present invention.

The light guide plate according to the present invention has a feature that the light distribution is controlled by removing a pattern on the lower surface of the light guide plate and adjusting only the slope angle of the lower surface.

That is, in the light guide plate according to the present invention, a pattern is not formed on the lower surface, and the lower surface is formed as a curved inclined surface so that light emitted at a critical angle or less with respect to the incident surface can be reflected and emitted to the outside.

Conventionally, a light guide plate in the form of a flat plate having a pattern formed on its surface has been used by using an extrusion method for passing a material of the light guide plate between rollers or an injection method for injecting the mold into a mold. However, as described above, the conventional light guide plate takes a long time to form a pattern that distributes the light evenly, resulting in a large amount of economic loss, and a pattern or a dot due to the pattern is reflected on the screen or moire. Due to the nature of the flat structure, the light incident from the light source is counted more than a predetermined portion toward the incident light surface, which has a problem in terms of light efficiency.

SUMMARY OF THE INVENTION The present invention is to solve these problems, and a curved slope is formed on the lower surface of the light guide plate to modify the angle of refraction of light, thereby controlling light distribution by refraction of light.

In particular, the present invention increases the inclination of the lower surface of the portion of the light guide plate close to the light source, and decreases the inclination toward the light incident surface, thereby receiving light that is incident parallel to the light incident surface of the light guide plate and directed toward the light incident surface. The liquid crystal panel may be reflected toward the liquid crystal panel in a portion adjacent to the light source.

That is, according to the present invention, since the refraction of the light gradually increases due to the slope toward the light incident surface, the light received from the light source is mostly emitted to the upper surface, which is excellent in terms of efficiency.

The features of the present invention as described above will be briefly summarized as follows.

As illustrated in FIG. 5, the light guide plate according to the present invention is inclined in a curved shape so as to reflect light incident through the light incident surface S1 and through which the light is incident through the light incident surface S1. , Facing the light incident surface S1 with the lower surface S4 interposed therebetween and facing the lower surface S4 with the light incident surface S1 and the light incident surface S2 interposed therebetween. It includes an upper surface S3 of the planar shape as viewed.

The lower surface S4 is formed in a convex shape toward the upper surface S3. In particular, the height of the light incident surface S2 is smaller than the height of the light incident surface S1. Accordingly, the lower surface S4 is formed in a convex shape toward the upper surface S3 between the light incident surface S1 and the carry-in light surface S2, as shown in FIG. 5. It is formed in such a manner that the inclination is lowered toward the light incident surface S2 from S1).

The upper surface S3 is an active area AA through which light incident through the light incident surface S1 is output to the outside, and is close to the light incident surface, so that light incident through the light incident surface cannot be output to the outside. And a light incident region NA.

In the lower surface S4, the inclination angle of the curve of the light incident region lower surface X corresponding to the light incident region NA is incident in parallel to the light incident surface S1, and the upper surface is incident on the light incident surface S1. After refracting at a critical angle in the S3 direction, the light reflected from the upper surface S3 is reflected at the upper surface S3 to be emitted to the outside.

In particular, the inclination angle of the curve of the bottom surface X of the light incident region is formed at any one of angles larger than 2.34 ° and smaller than 3 ° based on the horizontal line H1 parallel to the upper surface S1.

In the lower surface S4, the inclination angle of the curve of the active area lower surfaces Y and Z corresponding to the active area AA has an angle smaller than the inclination angle of the curve of the light incident area lower surface X.

The active area lower surfaces Y and Z are again the first active region lower surface Y adjacent to the light incident surface S1 and the second active region lower surface Z adjacent to the light incident surface S2. It can be divided into. The inclination angle of the curve of the lower surface Y of the first active region may be greater than the inclination angle of the curve of the lower surface Z of the second active region. The inclination angle of the curve of the lower surface V of the first active region may be the same as the inclination of the curve of the lower surface Z of the second active region.

As described above, the height of the incident light surface S2 may be smaller than the height of the incident light surface, and in particular, the height of the incident light surface S2 may have a value of 0 mm to 0.05 mm. That is, the height of the light incident surface S2 may be variously set according to the area or size of the light guide plate 120, but may be formed to be 0.05 mm or less.

Some of the light incident on the light incident surface S1 may proceed to the light incident surface S2 and may exit. Therefore, by minimizing the height of the light incident surface, the light is counted by minimizing the cross-sectional area of the light incident surface S2. Can be adjusted.

In the following, the above contents are summarized with reference to the drawings.

First, referring to FIG. 5, the light guide plate 120 according to the present invention has a height of the light incident surface S1 facing the light source 171 and to which light output from the light source 171 is received. It is formed higher than the height of the said light incident surface S2 formed in the opposite side to S1.

In particular, the height of the incident light surface (S2) may be formed small to have a maximum of 0.05mm. In the related art, since the pattern closer to the light incident surface S2 had to be formed on the lower surface, the height of the light incident surface S2 could not be reduced. However, in the case of the present invention, the pattern is not formed on the lower surface S4. Therefore, the height of the incoming light incident surface S2 can be minimized.

Therefore, the amount of light leaking out of the light guide plate 120 through the incoming light incident surface S2 can be reduced.

When the height of the light incident surface S1 is greater than the height of the light incident surface S2 when the upper surface S3 of the light guide plate 120 is a reference, the bottom surface S4 of the light guide plate is the light incident surface S1. ) Is inclined in the direction of the incoming light incident surface S2.

Further, the inclination of the lower surface of the portion of the light guide plate that is close to the light source, that is, the lower surface of the light incident region X is increased, and the light incident plate S2 is closer to the light incident surface S2, that is, the lower surface of the active region Y and Z. By reducing the inclination, the light K that is incident in parallel to the light incident surface S1 of the light guide plate and directed toward the light incident surface S2 can be reflected in the liquid crystal panel direction in a state adjacent to the light source.

Next, referring to FIG. 6, the inclination angle of the bottom surface X of the light incident region is formed larger than the inclination angles of the bottom surfaces Y and Z of the active region of the light guide plate S4.

That is, in order to output the light K incident in the light guide plate parallel to the light incident surface S1 to the upper surface S3 of the light guide plate through only minimal reflection inside the light guide plate, the active light is emitted from the light incident surface S1 of the light guide plate. The inclination angle of the lower surface to the area AA, that is, the light incident region lower surface X should be 2.34 ° or more. The reason why the inclination angle of the light incident region lower surface X should be 2.34 ° or more is as follows.

For example, the light K incident in parallel to the light incident surface S1 of the light guide plate is, as illustrated in FIG. 6, a line perpendicular to the light incident surface S1 or parallel to an upper surface of the light guide plate. It is refracted at an angle of 42.16 ° with respect to the line (hereinafter, simply referred to as 'first horizontal line') H1 and transmitted to the upper surface of the light guide plate.

The light K transmitted to the upper surface S3 of the light guide plate is, in the upper surface S3, a surface perpendicular to the upper surface S3 or a surface parallel to the light incident surface (hereinafter, simply referred to as 'first vertical line'). (Referred to herein as simply 'first angle c1') to the lower surface of the light guide plate.

In other words, in Snell's law, if the angle of incidence is less than the critical angle, refraction occurs between the two media, and if the angle of incidence is greater than the critical angle, reflection occurs between the two media.

Therefore, when the critical angle between the light guide plate and the air is 42.16 °, the light incident in parallel to the light incident surface S1 of the light guide plate is refracted by the critical angle 42.16 ° to the upper surface S3. The light transmitted to the upper surface is incident on the upper surface S3 in a state of forming 47.84 ° (first angle c2) with the first vertical line V1.

Since the first angle c1 (47.84 °) is greater than the critical angle (42.16 °), the light K does not pass through the upper surface S3 to go outside of the light guide plate, and in particular, the lower surface S4 of the lower surface S4. The light incident region is reflected in the lower surface (X) direction.

Since the tangent (hereinafter, simply referred to as 'second horizontal line') H2 of the light incident region lower surface X is inclined at 2.34 ° with respect to the first horizontal line H1, the light reflected from the upper surface S3 is reflected. Is on the bottom surface X of the light incident region at an angle of c1-2.34 ° (hereinafter, simply referred to as a 'second angle c2') with respect to the first vertical line V1 perpendicular to the first horizontal line H1. After being incident, the light is reflected back toward the upper surface S3. That is, the light reflected on the bottom surface X of the light incident region maintains a second angle c2 at a vertical line perpendicular to the second horizontal line H2 (hereinafter, simply referred to as a “second vertical line”) V2. In one state, the light is reflected toward the upper surface S3.

The light reflected in the direction of the upper surface S3 is incident on the upper surface S3 in a state inclined by a third angle c3 with respect to the first vertical line V1.

It can be seen that the third angle c3 formed by the light incident on the upper surface S3 with the first vertical line V1 is 42.16 ° according to Equation 1 below.

Figure pat00001

Since the third angle C3 is equal to the critical angle, the light incident on the upper surface S3 in the third angle is not passed through the upper surface S3 and is not output to the outside of the light guide plate.

In order for the light to pass through the upper surface S3, that is, to be refracted and output to the outside of the light guide plate, the third angle C3 must be smaller than a critical angle.

The third angle C3 is changed according to the inclination (2.34 °) of the first angle C1 and the bottom surface X of the light incident region. However, the first angle C1 is a refractive angle of light incident and refracted by the light entering the light guide plate through the incident surface when the light K is incident in parallel to the light incident surface S1. Has a value.

Therefore, in order for the third angle C3 to be smaller than the critical angle, the inclination angle formed by the bottom surface X of the light incident region should be greater than 2.34 °.

However, when the inclination angle becomes too large, light incident from the light incident surface S1 and traveling toward the light incident surface S2 may be disturbed. As a result of various simulations, the inclination angle is preferably smaller than 3 °.

That is, light incident on the light incident surface S1 and reflected on the upper surface S3 and then reflected again on the lower surface X of the light incident region and directed toward the upper surface S3 passes through the upper surface S3. In order to be refracted to the outside, the angle between the light reaching the upper surface S3 and the first vertical line V1 should be smaller than the grain boundary angle. In order to satisfy this, the angle with respect to the first horizontal line H1 of the bottom surface X of the incident region should be 2.34 ° or more.

Simulation results of the present invention as described above are shown in FIG. 7. That is, FIG. 7A illustrates a light distribution simulation result of a conventional light guide plate in which a lower surface is inclined in a straight line instead of a curve, and a light incident region NA in which light is not output to the outside is spaced far from the light incident surface. It can be seen that a lot of light is distributed in the region close to the incoming light incident surface S2.

However, Figure 7 (b) shows the light distribution simulation results for the light guide plate according to the present invention, the light receiving region (NA) in which light is not output to the outside is less spaced from the light receiving surface, the center portion of the light guide plate It can be seen that many lights are distributed.

In the case of the light guide plate using the conventional pattern, the size of the pattern is not constant, and there is a difference in the light distribution characteristics of the simulation light guide and the actual light guide plate. In addition, less errors occur in the simulation results and the light distribution characteristics of the actual light guide plate. Therefore, the present invention has the feature that the design and manufacture of the light guide plate can be simplified more.

Next, referring to FIG. 8, by forming the pattern 129 in the center portion of the light guide plate, a circularly bright part may be generated in the center portion of the light guide plate.

That is, as shown in (b) of FIG. 7, the light guide plate according to the present invention reduces the light incident region NA in which light is not output, and is an intermediate portion between the light incident surface S1 and the light incident surface S2. Since light can be collected, the efficiency of the light guide plate can be improved.

Such light is distributed evenly up and down at the middle of the light incident surface S1 and the light incident surface S2. However, when the light output from the light guide plate is concentrated in a circular state at the center portion of the light guide plate, the light efficiency may be maximized when the light is directed toward the liquid crystal panel.

To this end, the present invention, as shown in Figure 8, to form a pattern in a circular portion in the center portion of the upper surface (S3).

Briefly summarized the present invention as described above is as follows.

Conventional light guide plates are generally formed in a flat plate-like structure, and fine patterns have been processed on the lower surface of the light guide plate. However, instead of forming a pattern on the lower surface of the light guide plate according to the present invention, the lower surface is configured to be inclined in a curved shape. Conventionally, there has been an inclined light guide plate, but the lower surface of the conventional inclined light guide plate is inclined in a straight line shape, and the inclination angle of the lower surface is formed by the first equation. On the other hand, the lower surface of the light guide plate according to the present invention controls the reflection and refraction of light by adjusting the inclination of the lower surface by a quadratic or cubic equation.

In addition, the conventional light guide plate generates moire because the regular arrangement of the pattern and the pattern pixel spacing overlap, but the light guide plate according to the present invention does not have a pattern formed on the lower surface thereof, so that the moire due to the pattern ( Moire and dot reflection do not occur.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

110: cover bottom 120: light guide plate
130: optical sheet portion 140: guide panel
150: liquid crystal panel 160: case top
170: light source unit 121: reflector
120: light guide plate

Claims (10)

A light incident surface on which light is incident;
A lower surface inclined in a curved shape to reflect light incident through the light incident surface;
A light incident surface facing the light incident surface with the lower surface interposed therebetween; And
A light guide plate comprising a top surface facing the bottom surface with the light incident surface and the incoming light incident surface therebetween. The method of claim 1,
The lower surface is formed in a convex shape toward the upper surface. 3. The method of claim 2,
The upper surface includes an active region in which light incident through the light incident surface is output to the outside, and a light incident region in which light incident through the light incident surface is not output to the outside because it is close to the light incident surface,
Among the lower surfaces, the inclination angle of the curve of the lower surface of the light incident region corresponding to the light incident region is incident in parallel to the light incident surface, is refracted at a critical angle from the light incident surface to the upper surface direction, and then reflects light reflected from the upper surface. And a light guide plate formed at an angle capable of reflecting in the upper surface direction to be emitted to the outside. The method of claim 3, wherein
The inclination angle of the curve of the lower surface of the active region corresponding to the active region of the lower surface has an angle smaller than the inclination angle of the curve of the lower surface of the light incident region. 5. The method of claim 4,
A lower surface of the active region includes a lower surface of a first active region proximate to the light incident surface and a lower surface of a second active region proximate to the incoming light incident surface,
The inclination angle of the curve of the lower surface of the first active region is greater than the inclination angle of the curve of the lower surface of the second active region. The method of claim 3, wherein
A lower surface of the active region includes a lower surface of a first active region proximate to the light incident surface and a lower surface of a second active region proximate to the incoming light incident surface,
The inclination angle of the curve of the lower surface of the first active region is the same as the inclination of the curve of the lower surface of the second active region. The method of claim 3, wherein
The inclination angle of the curve of the lower surface of the light incident region corresponding to the light incident region of the lower surface may be formed at any one of angles larger than 2.34 ° and smaller than 3 ° based on a horizontal line parallel to the upper surface. Light guide plate. The method of claim 3, wherein
The height of the said incoming light incident surface is smaller than the height of the said light incident surface, The light guide plate characterized by the above-mentioned. The method of claim 3, wherein
The height of the light incident surface has a light guide plate, characterized in that any one of 0mm to 0.05mm. Guide panel;
The light guide plate according to any one of claims 1 to 9 disposed on the guide panel;
A liquid crystal panel disposed on an upper end of the light guide plate to output an image; And
And a light source unit disposed on a side of the light guide plate to inject light into the light incident surface of the light guide plate.
KR1020120103497A 2012-09-18 2012-09-18 Light guide panel KR102009855B1 (en)

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Application Number Priority Date Filing Date Title
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10260315A (en) * 1997-03-17 1998-09-29 Dainippon Printing Co Ltd Lens light guide plate and surface light source unit using the same
KR20040012393A (en) * 2002-08-03 2004-02-11 삼성전자주식회사 Back light assembly and liquid crystal display
KR100559966B1 (en) * 1999-03-04 2006-03-13 삼성전자주식회사 LCD module having a light guide plate provided with a space for accommodating PCB
KR20080036204A (en) * 2005-08-26 2008-04-25 고쿠리츠다이가쿠호진 도호쿠다이가쿠 Liquid crystal display and light guide plate

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10260315A (en) * 1997-03-17 1998-09-29 Dainippon Printing Co Ltd Lens light guide plate and surface light source unit using the same
KR100559966B1 (en) * 1999-03-04 2006-03-13 삼성전자주식회사 LCD module having a light guide plate provided with a space for accommodating PCB
KR20040012393A (en) * 2002-08-03 2004-02-11 삼성전자주식회사 Back light assembly and liquid crystal display
KR20080036204A (en) * 2005-08-26 2008-04-25 고쿠리츠다이가쿠호진 도호쿠다이가쿠 Liquid crystal display and light guide plate

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