TW201537247A - Light guiding plate and backlight unit comprising the same - Google Patents

Abstract

Disclosed a light guiding plate including a prism pattern, which has a top apex part of an arc shape in a vertical section, on a top surface thereof, wherein the prism pattern satisfies Equation 1, thereby having excellent straightness and brightness of the light emitted therefrom, and a backlight unit including the same.

Description

Light guide plate and backlight unit therewith

The present invention relates to a light guide plate and a backlight unit including the same, and more particularly to a light guide plate having excellent effects in realizing a screen split drive and a backlight unit including the same.

Due to the technology of image display devices, the largest part of which is the traditional CRT screen, has been greatly developed in recent years, becoming wider, lighter and even flexible to allow curved image display devices such as LCD, OLED, electronic paper and the like. Has been introduced in large numbers. In addition, due to the active search for such image display devices, image display devices having large areas have now been developed competitively.

The development of the image display device extends the display screen of the device. However, it has recently been shown that the screen has been extended beyond the human field of view, thus reaching its limits. For this reason, this research has focused on improving image quality, ie resolution, contrast ratio, color reproduction or the like.

Regarding the improvement of image quality, among the recently introduced technologies, there is a screen division driving method (local dimming) which divides the backlight unit into a plurality of sections and connects the luminance of the light source with the image signal to reduce the dark portion of the image. Brightness increases the brightness of the bright part, so the contrast ratio is greatly increased and the sharpness is increased at the same time.

In order to efficiently perform such a screen split driving, there is a need for a light guide plate that emits light of a light source uniformly at a high brightness with straightness.

In this regard, Korean Patent Laid-Open Publication No. 2011-50270 proposes a laser concave pattern having a pattern formed at the bottom of a light guiding plate and a stencil type light guiding plate formed at the top, however, it is still not suitable for improvement. The straightness of the surface source.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a light guide plate having excellent straight forward characteristics (hereinafter simply referred to as "straightness") and lightness, and thus usefully applied to realize screen split driving.

Another object of the present invention is to provide a backlight unit including the above-described light guiding plate.

The above objects of the present invention will be achieved by the following characteristics:

(1) A light guide plate comprising a 稜鏡 pattern having a curved apex portion in a vertical portion on a top surface thereof, wherein the 稜鏡 pattern satisfies the following formula 1: [Formula 1] 0.350 (mm/radian ² ) < {H/ ((radian (A)) * (radian (B))} / (n*100) < 1.400 (mm/radian ² ) (where H (mm) is the height of the 垂直 in the vertical part, A ( °) is the angle between the base and the bevel of the middle of the vertical portion, B (°) is the angle between the connecting line and the base, which is connected from the center of the base to the top arc of the middle of the vertical portion. One point, and n is the reflectivity of the material forming the 稜鏡 pattern.

(2) The light guide plate according to (1) above, the height H is 20 to 50 mm.

(3) The light guiding plate according to (1) above, the angle A is 25° to 50°.

(4) The light guide plate according to (1) above, wherein the angle B is 10° to 75°.

(5) The light guide plate according to (1) above, wherein the pattern is composed of a group consisting of (meth)acrylic resin, carbonate resin, styrene resin, hydrocarbon resin, ester resin, and copolymer thereof The material of at least one selected from the group is formed.

(6) The light guiding plate according to (1) above, further comprising a light scattering pattern formed on a bottom thereof.

(7) The light guiding plate according to (6) above, wherein the light scattering pattern is a concave or convex pattern.

(8) A backlight unit comprising the light guiding plate according to any one of (1) to (7) above.

(9) An image display device comprising the backlight unit according to (8) above.

The light guide of the present invention has improved straightness of the light emitted therefrom, and thus is usefully applied to achieve screen split driving, that is, local dimming.

An image display device having an inventive light guide plate can uniformly emit light without a hot spot.

In addition, the image display device including the creative light guide plate has an excellent effect in realizing the screen split driving, thereby making the screen display excellent in contrast ratio and sharpness.

The invention discloses a light guiding plate comprising a 稜鏡 pattern and a backlight unit comprising the same, wherein on the top surface of the light guiding plate, there is an arc-shaped apex portion in the vertical portion, wherein the 稜鏡 pattern satisfies the formula 1, thereby having Excellent straightness and brightness of the light emitted from it.

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

The light guide plate of the present invention includes a 稜鏡 (hereinafter referred to as "circle") pattern having an arcuate apex portion in the vertical portion on the top surface thereof.

The circle satisfies the following formula 1, so that the straightness and brightness of the light emitted therefrom can be remarkably improved, and thereby the screen split driving ("local dimming") can be effectively realized.

[Formula 1] 0.350 (mm/radian ² ) < {H/ ((radian (A)) * (radian (B))} / (n*100) < 1.400 (mm/radian ² ) (where H (mm) ) is the height of the ridge in the vertical part, A (°) is the angle between the base and the bevel of the ridge in the vertical part, and B (°) is the angle between the connection line and the base, which is from the center of the base Beginning to connect a point in the top arc of the ridge in the vertical portion, and n is the reflectivity of the material forming the 稜鏡 pattern.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates a schematic shape of a vertical section of a file according to an embodiment of the present invention. The vertical portion of the circular ridge illustrated in Fig. 1 has a bilaterally symmetrical shape in which the apex portion of the ridge has an arc shape.

In the present invention, the height H of the round ridge in the vertical portion may be 20 to 50 mm, and preferably 25 to 50 mm. When the height H is within the above range, the straightness and brightness of light emitted from the light guiding plate can be further improved.

In the present invention, the angle A between the base and the bevel of the round ridge in the vertical portion may be 25 to 50, and preferably 30 to 50. When the angle A is within the above range, the straightness and brightness of light emitted from the light guiding plate can be further improved.

In the present invention, the angle B between the connecting line and the base may be 10° to 75.0°, and preferably 10° to 70°, and the connecting line connects the top curved portion of the vertical portion from the center of the base. One point in the middle. When the angle B is within the above range, the straightness and brightness of light emitted from the light guiding plate can be further improved.

In the present invention, the reflectance n of the material forming the 稜鏡 pattern of the circle may be from 1.41 to 1.61, and preferably from 1.45 to 1.59. When the reflectance n is within the above range, the straightness and brightness of light emitted from the light guiding plate can be further improved.

In the present invention, the base length P of the round ridge in the vertical portion may be 100 to 250 mm, and preferably 130 to 210 mm. When the base length P is within the above range, the straightness and brightness of light emitted from the light guiding plate can be further improved.

According to the present invention, the height H of the round ridge in the vertical portion, the angle A between the base portion and the oblique side, the connecting line connecting the point of the top arc from the center of the base, and the angle B between the base portions, and The base length P thereof satisfies the above range, and the straightness and brightness of light emitted from the light guiding plate can be synergistically increased, and thereby the screen split driving ("local dimming") can be further effectively realized.

Referring to Fig. 1, there is illustrated an embodiment of the present invention, wherein the above four parameters have a value within each of the above specific ranges, including the center of the upper curved circle of the round file according to the present invention (origin O) It can be located above the base of the lower end or outside the round file. Therefore, the sector radius R including the upper arc of the circle may have different values.

In the present invention, the circular pattern can be formed of a material including a light-transmitting resin.

The light-transmitting resin is not particularly limited as long as it is used in the related art, but may include, for example, (meth)acrylic resin, carbonate resin, styrene resin, olefin resin, lipid resin, and copolymer thereof, and preferably, used (Meth)acrylic resin or (meth)acrylic-styrene copolymer resin.

Preferably, the olefin resin is a cycloolefin resin, and preferably, the lipid resin is an amorphous polyester resin.

The (meth)acrylic resin may include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (methyl) Acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, phenyl (meth) acrylate, chlorophenyl (meth) acrylate, and the like. Among these, a methyl (meth) acrylate resin having high transmittance is preferably used.

More preferably, the (meth)acrylic resin is a resin obtained by copolymerization with a monofunctional unsaturated monomer. In the copolymerization, preferably, the (meth)acrylic resin is included in the range of 60 wt.% or less of the total weight of the copolymer resin, and more preferably, about 50 wt.% or less.

The monofunctional unsaturated monomer copolymerized with the (meth)acrylic resin may include an unsaturated acid compound including (meth)acrylic acid, acrylic acid, and the like, and styrene, acrylonitrile, maleic anhydride, Aniline, cyclohexylm-butyleneimine, etc., and preferably styrene. These can be used alone or in combination of two or more of them.

Copolymerization of the (meth)acrylic resin with the monofunctional unsaturated monomer can be readily carried out by those of ordinary skill in the art to which the present invention pertains.

The light guiding plate of the present invention may further comprise a light scattering pattern formed on the bottom thereof. With such a light scattering pattern, light emitted through the top surface of the light guide plate can have a further enhanced uniformity of light emitted therefrom.

The shape of the light scattering pattern may include any one of light scattering patterns used in the related art, and is not particularly limited. For example, the light scattering pattern can have a concave or convex pattern applied to the bottom of the light guide. In particular, the shape of the pattern may include a lens, a convex lens, a meander or a polygon, and the like. The convex lens shape may have a cross section such as a semicircle or a semi-ellipse. The light scattering patterns may be arranged continuously or at predetermined intervals from each other. Alternatively, the density of the scatter pattern may increase as the pattern is placed away from the source, or the density may remain fixed regardless of the distance.

The substrate of the light guiding plate of the present invention may comprise a light-transmitting resin, and its form is not particularly limited, but the same light-transmitting resin as that of the above-described circular pattern resin may be used. The substrate may further comprise at least one of a UV-absorber, a blowing agent, an antioxidant, or a release agent.

Like a conventional light guide plate, the light guide plate of the present invention may further include a functional layer provided on the bottom or top surface, or may be formed as a functional light guide plate. The substrate of the functional layer may use the same resin of the above-mentioned resin exemplified as the substrate of the light guiding plate or the same resin which may use a substrate such as a light guiding plate. In addition, other resins different from the matrix may also be used. The functional layer may further include at least one of a UV-absorber, a heat stabilizer, an antioxidant, an antistatic agent, a fluorescent whitening agent, and a releasing agent, and alternatively, these functional materials may be added to the substrate.

A method of preparing a light guiding plate is not particularly limited, however, various procedures such as extrusion molding, vacuum molding, hot press molding, film lamination, solvent bonding, surface coating, UV curing, heat curing, or the like may be included. However, in view of ease of manufacture, extrusion or UV curing coating is preferably used. In view of manufacturing cost and productivity, extrusion molding is preferably used.

In the backlight unit according to the present invention, as illustrated in FIG. 2, when the light source 200 is located at the side of the light guiding plate 100, the round figure pattern 130 may be disposed on the top surface of the light guiding plate 100 such that the light source 200 is The light source 200 is installed at both ends in the longitudinal direction of the circular pattern 130, or the light source 200 is installed in a lateral direction orthogonal to the above direction.

Preferably, as schematically illustrated in FIG. 3, in view of reducing the hot spot and improving the uniformity of light emitted therefrom, it is preferred that the direction of the circle pattern 130 is such that the light source 200 is mounted thereon. Set the two ends of the longitudinal direction. Further, the light guiding plate 100 may also be provided with a reflection sheet 300 on the bottom thereof. The reflection sheet 300 can be used to reflect light emitted toward the bottom of the light guiding plate 100, and then re-inject the reflected light onto the light guiding plate 100, and any conventional reflection sheet used in the related art can be employed for the reflection sheet 300 without particular limitation. .

Meanwhile, the light guiding plate 100 may further include a diffusion sheet, a microlens sheet, a cymbal sheet, a reflective polarizing brightness enhancing film (DBEF) or a protective sheet or the like on the top surface thereof.

The light guide panel 100 of the present invention can be included as an element of an image display device. The image display device is not particularly limited as long as the device requires an alternative surface light source to display an image, and may include, for example, a liquid crystal display (LCD). Furthermore, the light guide plate 100 described above can also be used as an element for providing a surface light source to a general illumination device.

Hereinafter, the preferred embodiments are presented to more specifically describe the present invention. However, the following examples are provided to illustrate the invention, and it is obvious to those skilled in the art that various alternatives and modifications may be made within the scope and spirit of the invention. These substitutions and modifications are suitably included in the scope of the appended claims.

Examples and comparative examples

A light guiding plate was prepared using MMA-styrene (reflectance: 1.55), and a circular pattern having the elements and shapes described in Table 1 below was formed on the top surface of the prepared light guiding plate. Herein, the base length of the pattern in the vertical portion is 150 μm. The light scattering pattern formed on the bottom of the light guide plate is a concave ellipsoid with a depth of 70 μm, a longitudinal length of 250 μm, and a lateral length of 20 μm. Furthermore, in order to determine the uniformity of light emitted therefrom, the distribution density of the pattern increases as the pattern becomes farther away from the light source to be densely formed.

example 1 to 8 And comparative examples 1 to 4: height H The change

Experimental example 1

The LED light source was disposed on the side of the light guide plate prepared above, and the straightness and relative brightness of the light emitted from the light guide plate were measured under the condition that the LED light emission angle was 120° and the LED light intensity was 35 lumens.

The straightness is evaluated by the relative ratio of the brightness of the light emitted from the straight line portion to the brightness of the light emitted from the other straight line portion, the straight line portion connecting the light source in the N+3 block of the light guiding plate, the other straight line portion connecting the light guiding plate The light source in the Nth block, when the LED light sources in the Nth block (each block includes 8 to 12 LED light sources) are turned on, the light sources in the other blocks are turned off. When the above ratio is lowered, the straightness of the light is improved. The brightness was measured using a luminance meter (model name: BM-7, TOPCON, Japan).

The measurement results are shown in Table 2 below.

Examples 9 and 10 and Comparative Examples 5 and 6: Variations in the angle A between the base and the bevel [Table 3]

Experimental example 2

The LED light source was mounted on one side of the light guide plate prepared above, and the straightness and relative brightness of the light emitted from the light guide plate were measured under the conditions of an LED light emission angle of 120° and an LED light intensity of 35 lumens.

The measurement results are shown in Table 4 below.

example 11 to 13 And comparative examples 7 and 8: Angle between the connecting line and the base B Change

Experimental example 3

The LED light source was mounted on one side of the light guide plate prepared above, and the straightness and relative brightness of the light emitted from the light guide plate were measured under the conditions of an LED light emission angle of 120° and an LED light intensity of 35 lumens.

The measurement results are shown in Table 6 below.

example 14 to 16 And comparative examples 9 and 10 : Changes in graphic components ( Reflectivity n)

Experimental example 4

The LED light source was mounted on one side of the light guide plate prepared above, and the straightness and relative brightness of the light emitted from the light guide plate were measured under the conditions of an LED light emission angle of 120° and an LED light intensity of 35 lumens.

The measurement results are shown in Table 8 below. [Table 8]

Referring to Tables 2, 4, 6, and 8 above, it can be seen that the light guide plate prepared in the example exhibits significantly improved brightness and straightness of light emitted therefrom, and thus is usefully applied to achieve screen split driving.

However, it can be seen that the light guide plate prepared in the comparative example having parameters exceeding the scope of the present invention exhibits a significantly reduced straightness and average brightness of the light emitted therefrom as compared with the example.

100‧‧‧Light guide
130‧‧‧稜鏡图
200‧‧‧radial light source
300‧‧‧reflector
A, B‧‧‧ angle
H‧‧‧ Height

The above and other objects, features and other advantages of the present invention will become more apparent from the aspects of the accompanying claims < 2 is a perspective view schematically illustrating a backlight unit according to an embodiment of the present invention; and FIG. 3 is a vertical sectional view schematically illustrating a backlight unit according to an embodiment of the present invention.

A, B‧‧‧ angle

H‧‧‧ Height

Claims (9)

A light guide plate comprising a 稜鏡 pattern, wherein a vertical portion on a top surface has an arc-shaped apex portion, wherein the 稜鏡 pattern satisfies the following formula 1: [Formula 1] 0.350 (mm/radian) ² ) < {H/ (radian (A)) * (radian (B))} / (n*100) < 1.400 (mm/radian ² ) (where H (mm) is the 稜鏡 in the vertical part a height, A (°) is an angle between a base portion and a hypotenuse of the ridge in the vertical portion, and B (°) is a angle between a connecting line and the base portion, the connecting line A center of the base begins to join a point in the top arc of the crucible in the vertical portion, and n is a reflectivity of a material forming the pattern. The light guide plate as described in claim 1, wherein the height H is 20 to 50 mm. The light guide plate as recited in claim 1, wherein the angle A is 25° to 50°. The light guide plate as described in claim 1, wherein the angle B is 10° to 75°. The light guide plate according to claim 1, wherein the pattern is composed of a (meth)acrylic resin, a carbonate resin, a styrene resin, an olefin resin, a resin, and A material of at least one selected from the group consisting of copolymers is formed. The light guide plate as described in claim 1 further includes a light scattering pattern formed on a bottom portion thereof. The light guide plate of claim 6, wherein the light scattering pattern is a concave pattern or a convex pattern. A backlight unit comprising the light guiding plate according to any one of claims 1 to 7. An image display device comprising the backlight unit of claim 8 of the patent application.