KR101845170B1 - Light guide plate, manufacturing method of light guide plate, backlight unit comprising the light guide plate and display device comprising the backlight unit - Google Patents

Abstract

The present invention relates to a light guide plate and a backlight unit and a display device including the same capable of realizing an organic light emitting diode or a liquid crystal display device with high color reproducibility with simple processes and low costs without using an expensive quantum dot (QD) film by applying a blue phase liquid crystal film to a light guide plate of a backlight unit to narrow wavelength linewidths of red (R), green (G), and blue (B). The light guide plate comprises a light receiving surface, a reflection surface, and a light exit surface.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide plate, a method of manufacturing a light guide plate, a display unit including a backlight unit including a light guide plate, and a backlight unit. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present application relates to a light guide plate, a method of manufacturing a light guide plate, a backlight unit including a light guide plate, and a display device including the backlight unit.

A liquid crystal display (LCD) has many advantages such as a low production cost, etc. However, when compared with an organic light emitting diode (OLED), the color reproducibility is low, . For example, to increase the color reproducibility of a display that implements colors by three elements of red (R), green (G), and blue (B), each of red (R), green (G), blue The wavelength line width of the red (R), green (G) and blue (B) wavelength of the organic light emitting diode (OLED) is much narrower than that of the liquid crystal display. In order to solve such a problem, by narrowing the wavelength line width of red (R), green (G) and blue (B) by filtering the wavelength line width of light emitted from the backlight with a quantum dot (QD) Attempts have been made to improve the color reproducibility and to improve the color reproducibility of the display by changing the material of the color filter.

However, in the case of the above method of improving the color reproducibility using the QD film, the color reproducibility is still lower than that of the organic light emitting diode (OLED), and when the color reproducibility is improved by using the QD film, Because of the high cost of making very small nano-sized particles in the manufacturing process, the price of one quantum dot film is very high, which increases the cost of the display.

Therefore, in order to solve the above-mentioned problems, it is required to develop a new optical film which is less expensive than the QD film and can produce a wavelength region with a narrower band width.

The present application is based on the idea that a blue phase liquid crystal film is applied to a light guide plate of a backlight unit to narrow the wavelength linewidth of red (R), green (G) and blue (B) A light guide plate capable of realizing an organic light emitting diode or a liquid crystal display device of high color reproducibility at low cost, a backlight unit including the same, and a display device.

This application relates to a light guide plate. According to the exemplary light guide plate of the present application, by narrowing the wavelength line widths of red (R), green (G), and blue (B) without using expensive QD films, the organic light emitting diode or liquid crystal display .

Hereinafter, the light guide plate of the present application will be described with reference to the accompanying drawings, and the attached drawings are illustrative, and the scope of the present application is not limited by the attached drawings.

1 is a diagram schematically showing a cross section of a light guide plate 110 according to an embodiment of the present application.

As shown in Fig. 1, the light guide plate 110 of the present application has at least four surfaces, for example, a light receiving surface 1101, a reflecting surface 1102, and a light output surface 1103.

The light receiving surface 1101 refers to a surface on which light emitted from the light source 160 is incident and the light guiding plate 110 may have at least two light receiving surfaces 1101. In one example, ) May mean a side surface or a surface in the thickness direction of the light guide plate 110.

The reflective surface 1102 includes a first region 1102A and a second region 1102B. The first region 1102A is a region where a reflection pattern for reflecting light incident from the light receiving surface 1101 is formed and the second region 1102B is a region where the reflection pattern is not formed it means.

The reflection pattern may be formed in various patterns known in the art such as a lattice pattern, a prism pattern, or a dot pattern, and is not particularly limited.

2 is a view schematically showing a reflective surface of a light guide plate 110 on which a lattice pattern is formed. As shown in FIG. 2, the reflective surface 1102 may include a first region 1102A having a lattice pattern and a second region 1102B having no lattice pattern.

3 is a diagram schematically showing a reflecting surface 1102 of a light guide plate 110 having a dot pattern formed thereon. 3, the reflective surface 1102 may include a first area 1102A having a dot pattern formed thereon and a second area 1102B having no dot pattern formed thereon.

The reflection pattern may be formed on the reflective surface 1102 in a relief or a relief pattern.

The light emitting surface 1103 may be a surface on which the light reflected by the reflecting surface 1102 is emitted and a surface facing the reflecting surface 1102.

The light guide plate 110 of the present application includes a light reflection portion 120 formed on the reflection surface 1102. [

The light reflection part 120 includes a first liquid crystal, a second liquid crystal, and a third liquid crystal. The first liquid crystal means a liquid crystal having a reflection peak in a wavelength range of 400 to 500 nm and the second liquid crystal means a liquid crystal having a reflection peak in a wavelength range of 500 to 600 nm, Means a liquid crystal having a reflection peak in a wavelength range of from 700 nm to 700 nm.

In one embodiment, the liquid crystal may be a blue phase liquid crystal. The blue phase liquid crystal is a three-dimensional photonic crystal. The photonic band gap is controlled by appropriately doping chiral dopants to adjust the pitch, and a specific The wavelength can be strongly reflected. For example, a liquid crystal capable of selectively and strongly reflecting the wavelength line widths of red (R), green (G), and blue (B) can be produced by properly blending the amount of the chiral dopant in the blue phase liquid crystal. For example, the amount of the chiral dopant varies depending on the selectively reflecting wavelength, and therefore, the amount of the chiral dopant varies depending on the twist strength (HTP) of the chiral dopant and the average refractive index (n _avg ) Can be differently included according to the following general formulas 1 to 3 by using the intensity of the twist and the refractive index of the liquid crystal.

[Formula 1]

λ ₀ = n _avg × P ₀

In the general formula (1),? ₀ represents the central wavelength of reflection, n _avg represents the average refractive index of the liquid crystal, and P ₀ represents the pitch length of the helix appearing in the helical structure of the liquid crystal molecule.

[Formula 2]

The content of the chiral dopant (wt%) = 100 / ( P 0 × HTP)

In the general formula 2, HTP represents the intensity of the twist of the chiral dopant, and P ₀ represents the pitch length of the helix appearing in the helical structure of the liquid crystal molecule.

[Formula 3]

Content of chiral dopant (wt%) = 100 x (content of chiral dopant) / (content of liquid crystal + content of chiral dopant)

In one example, the first liquid crystal, the second liquid crystal, or the third liquid crystal may include 50 to 99 parts by weight of the liquid crystal polymer and 1 to 50 parts by weight of the chiral dopant doped in the liquid crystal polymer, But is not limited to.

The light reflection part 120 may further include a binder resin. The binder resin may be included in the light reflection part 120 in a cured state.

The binder resin may be a photo-curable polymer resin or a thermosetting polymer resin. As the photo-curable polymer resin, various active energy ray-curable resins known in the art can be used. For example, a silicone resin, an acrylic resin, an epoxy resin, a polyether resin, a polyester resin, an alkyd resin, , A polybutadiene resin, a polythiol polyene resin, and a polyurethane resin may be used, but there is no particular limitation. Alternatively, a photo-curing adhesive such as a photo-curable liquid crystal polymer compound such as Reactive Mesogen (RM) from Merk or Norland Optical Adhesive (NOA) from Norland can be used as a binder resin. As used herein, the term " active energy ray " refers to an electron beam such as microwaves, infrared (IR), ultraviolet (UV) A particle beam such as a neutron beam and an electron beam, and may be ultraviolet rays or electron beams. In addition, in the above, "active energy ray curable type" may mean that the above-mentioned curing can be induced by irradiation of active energy rays. In one example, the curing of the resin can be carried out through free radical polymerization or cationic reaction by irradiation of an active energy ray, and preferably free radical polymerization and cationic reaction can proceed simultaneously or sequentially together .

As the thermosetting polymer resin, various thermosetting resins known in the art can be used. For example, epoxy resin, phenol resin, polyimide resin, polyurethane resin, alkyd resin, melamine resin, silicone resin and urea resin At least one selected from the group consisting of the above-mentioned compounds may be used, but it is not particularly limited.

The binder resin may be included in the light reflection part 120 in an amount of 1 to 50 parts by weight based on 100 parts by weight of the liquid crystal. When the content of the binder resin is less than 1 part by weight, cross-linking between the polymers is not sufficient and the liquid crystal can not be fixed. If the content of the binder resin is more than 50 parts by weight, the reflection effect of the liquid crystal may sharply decrease.

1, the light reflection part 120 is formed on the entire surface of the reflection surface 1102, that is, the first area 1102A and the second area 1102B of the reflection surface 1102, As shown in FIG.

1, when the light reflection part 120 is formed on the entire reflection surface 1102 of the light guide plate 110, the light reflection part 120 is formed on the reflection surface 1102, 1 region 1102A and a second region 1102B, and the liquid crystal layer may include a first liquid crystal layer 121 including the first liquid crystal, a second liquid crystal layer including the second liquid crystal And a third liquid crystal layer 123 including the third liquid crystal.

The order of lamination of the first liquid crystal layer 121, the second liquid crystal layer 122 and the third liquid crystal layer 123 is not particularly limited and the order of lamination on the reflective surface 1102 of the light guide plate 110 A second liquid crystal layer 122 directly formed on the third liquid crystal layer 123 and a first liquid crystal layer 121 formed directly on the second liquid crystal layer 122. The third liquid crystal layer 123 is formed directly on the second liquid crystal layer 123, (I) a light guide plate / light reflection portion (third liquid crystal layer / second liquid crystal layer / first liquid crystal layer) in order. Also, although not shown, the light guide plate 110 including the light reflecting portion 120 according to the present application may be formed of a light guide plate / light reflecting portion (a third liquid crystal layer / a first liquid crystal layer / a second liquid crystal layer) (i) a light guide plate / light reflecting portion (second liquid crystal layer / first liquid crystal layer / third liquid crystal layer), (v) a light guide plate / light reflecting portion (second liquid crystal layer / third liquid crystal layer / first liquid crystal layer) (First liquid crystal layer / second liquid crystal layer / third liquid crystal layer) vi) light guide plate / light reflecting portion (first liquid crystal layer / third liquid crystal layer / second liquid crystal layer) Lt; / RTI >

The first liquid crystal layer 121 and the second liquid crystal layer 122 of the light reflection portion 120 and the third liquid crystal layer 122 of the light reflection portion 120 are formed on the entire reflective surface 1102, (123) may be formed by the following method. In one example, a third liquid crystal composition including a third liquid crystal having a reflection spectrum peak in a wavelength range of 600 to 700 nm is coated on a reflective surface 1102 on which a reflective pattern of the light guide plate 110 is formed, And a second liquid crystal composition including a second liquid crystal having a reflection spectrum peak in a wavelength range of 500 to 600 nm is coated on the third liquid crystal layer and cured to form a second liquid crystal layer, Layer 122 is coated with a first liquid crystal composition including a first liquid crystal having a reflection spectrum peak in a wavelength range of 400 to 500 nm on the second liquid crystal layer 122 and cured to form a first liquid crystal layer (121).

The first liquid crystal layer 121, the second liquid crystal layer 122, and the third liquid crystal layer 123 may be formed through various coating methods known in the art. For example, the coating may be performed by one or more methods selected from the group consisting of spin coating, blade coating, bar coating, imprinting and electronic printing, but is not limited thereto.

The curing is also carried out to cure the ultraviolet curable binder resin and the thermosetting binder resin described above and may be carried out through various thermosetting or photocuring methods known in the art.

The light guide plate 110 of the present application may further include a light absorbing layer 130 formed under the light reflecting portion 120.

4 is a diagram schematically showing a cross section of the light guide plate 110 of the present application including the light absorbing layer 130 of the present application.

As shown in FIG. 4, the light absorbing layer 130 may be formed under the light reflecting portion 120. The light absorbing layer 130 may remove unnecessary light transmitted through the light absorbing layer 130, It is possible to improve the color reproducibility.

4, the light guide plate 110 of the present application is formed on the light exit surface 1103 side of the light guide plate 110 and has a phase delay of 1/4 of the wavelength of the light reflected by the reflection surface 1102. [ The phase retardation film 140 may further include a phase retardation film 140. The phase retardation film 140 may increase the light efficiency of the display device.

The light guide plate 110 of the present application may further include a light reflecting layer 150 formed under the light reflecting portion 120. [

5 is a diagram schematically showing a cross section of the light guide plate 110 of the present application including the light reflection layer 150. As shown in FIG.

5, the light reflecting layer 150 may be formed under the light reflecting portion 120. In one example, the light reflecting layer 150 may be formed on the light reflecting portion 120 and the light absorbing layer 120, (Not shown).

The light reflection layer may include a first liquid crystal layer 151 including a first liquid crystal, a second liquid crystal layer 152 including a second liquid crystal, and a third liquid crystal layer 153 including a third liquid crystal. have.

5, the stacking order of the first liquid crystal layer 151, the second liquid crystal layer 152, and the third liquid crystal layer 153 of the light reflection layer is the same as that of the first liquid crystal layer 151 of the light reflection portion 120, The first liquid crystal layer 121, the second liquid crystal layer 122, and the third liquid crystal layer 123 may be formed in a reverse order.

The first liquid crystal layer 151 including the first liquid crystal in the light reflection layer 150, the second liquid crystal layer 152 including the second liquid crystal, and the third liquid crystal are included in the light reflection layer 150 The order of laminating the first liquid crystal layer 151, the second liquid crystal layer 152 and the third liquid crystal layer 153 when the third liquid crystal layer 153 is formed is not particularly limited. However, when a light reflection layer including a plurality of liquid crystal layers is formed so as to face the liquid crystal layer formed in the light reflection portion 120, the first liquid crystal layer 151, the second liquid crystal layer 152, The stacking order of the first liquid crystal layer 121, the second liquid crystal layer 122 and the third liquid crystal layer 123 in the light reflection part 120 formed in advance Do. When the liquid crystal layer and the light reflecting layer 150 of the light reflecting portion 120 are formed in the stacking order as described above, the light reflecting portion 120 reflects the right circularly polarized light and the light reflecting layer 150 reflects left circularly polarized light Or the light reflection part 120 reflects the left circularly polarized light and the light reflection layer 150 can reflect the right circularly polarized light so that the light efficiency of the display device can be increased.

In one example, the first liquid crystal layer 121 of the light reflection portion 120 and the first liquid crystal layer 151 of the light reflection layer 150 are opposed to each other, The third liquid crystal layer 123 of the light reflecting portion 120 and the third liquid crystal layer 152 of the light reflecting layer 150 oppose each other or the third liquid crystal layer 123 of the light reflecting portion 120 and the second liquid crystal layer 152 of the light reflecting layer 150 oppose each other, (153) are opposed to each other. In the above, " positioned to face " means to be formed so as to face each other directly.

5, the light guide plate 110 of the present application including the light reflecting portion 120, the light reflecting layer 150, and the light absorbing layer 130 may be formed of i) a light guide plate / light reflecting portion Layer / the second liquid crystal layer / the first liquid crystal layer) / the light reflection layer (the first liquid crystal layer / the second liquid crystal layer / the third liquid crystal layer) / the light absorption layer. (Ii) a light guide plate / light reflection portion (third liquid crystal layer / first liquid crystal layer / second liquid crystal layer), which is not shown, / Light reflection layer (second liquid crystal layer / first liquid crystal layer / third liquid crystal layer) / light absorption layer iii) light guide plate / light reflection portion (second liquid crystal layer / third liquid crystal layer / first liquid crystal layer) / light reflection layer Light reflection layer (first liquid crystal layer / first liquid crystal layer / third liquid crystal layer) / light reflection layer (third liquid crystal layer / third liquid crystal layer / second liquid crystal layer) / light absorption layer, (First liquid crystal layer / second liquid crystal layer / third liquid crystal layer) / light reflecting layer (third liquid crystal layer / second liquid crystal layer / second liquid crystal layer) / light absorbing layer, Light reflection layer (first liquid crystal layer / third liquid crystal layer / second liquid crystal layer) / light reflection layer (second liquid crystal layer / third liquid crystal layer / first liquid crystal layer) / light absorbing layer Liquid crystal layer) / light absorbing layer or the like.

In another embodiment, the light reflection portion 120 may be formed only in a part of the reflection surface 1102, that is, in the first region 1102A of the reflection surface 1102. [

6 is a schematic view of a section of the light guide plate 110 according to another embodiment of the present application and FIG. 7 is a sectional view of the light guide plate 110 In the figure).

6 and 7, when the light reflection part 120 is formed only on a part of the reflection surface 1102 of the light guide plate 110, the light reflection part 120 may include a plurality of liquid crystal layers, It may have a single-layer liquid crystal layer or a structure formed in a liquid crystal additive Sea-island form instead of a laminated structure. Means a shape in which a plurality of liquid crystal portions are partially distributed in the first region 1102A of the reflection surface 1102. In this case, In one example, the light reflection part 120 includes a first liquid crystal part 121 including a first liquid crystal, a second liquid crystal part 122 including a second liquid crystal, and a third liquid crystal part 122 including a third liquid crystal. And may include a liquid portion 123. 7, the first liquid crystal unit 121 is formed on a part of the first area 1102A of the reflective surface 1102 and the second liquid crystal unit 122 is formed on a part of the reflective surface 1102 Of the first area 1102A of the reflective surface 1102 is formed in a part of the first area 1102A where the first liquid part 121 is not formed and the third liquid part 123 is formed in a part of the first area 1102A of the reflective surface 1102, And may be formed in the remaining part where the first solution part 121 and the second solution part 122 are not formed. 7, it is preferable that the first liquid crystal unit 121, the second liquid crystal unit 122, and the third liquid crystal unit 123 are formed to have the same number. For example, The ratio of the number of the liquid crystal units 121, the second liquid crystal units 122, and the third liquid crystal units 123 may be 1: 1: 1, but the present invention is not limited thereto.

When the light reflection part 120 is formed only on a part of the reflection surface 1102, the order of the liquid crystal part formed in a part of the first area 1102A and the order of the first liquid part 121, The positions of the liquid portion 122 and the third liquid portion 123 are not particularly limited.

When the light reflection part 120 is formed only on a part of the reflection surface 1102 as described above, the first liquid crystal part 121, the second liquid crystal part 122, and the third liquid crystal part 122 of the light reflection part 120, (123) may be formed by the following method. In one example, a part of the reflection pattern of the light guide plate 110 having the reflection surface 1102 on which the reflection pattern is formed is coated with a first liquid crystal having a reflection spectrum peak in a wavelength range of 400 to 500 nm 1 liquid crystal composition is coated and cured to form a first liquid phase portion 121. A second liquid crystal layer is formed on a part of the reflection pattern where no first liquid crystal pattern is formed and a second liquid crystal layer having a reflection spectrum peak in a wavelength range of 500 to 600 nm A second liquid crystal part 122 is formed by coating and curing a second liquid crystal composition containing a liquid crystal, and a first liquid crystal pattern and a second liquid crystal pattern are not formed, And a third liquid crystal composition having a reflection spectrum peak in the wavelength range of the first liquid crystal layer 123 and the third liquid crystal layer 123 to form the third liquid crystal layer 123.

As described above, when the light reflection part 120 is formed only in a part, it is difficult to form the light reflection part 120 as a general coating method, so that the coating can be performed by an electronic printing method.

The curing is also carried out to cure the ultraviolet curable binder resin and the thermosetting binder resin described above and may be carried out through various thermosetting or photocuring methods known in the art.

The present application also relates to a backlight unit 100 including the light guide plate 110 described above.

The presently filed backlight unit includes a light source and the light guide plate 110 described above. The description related to the light guide plate 110 is the same as that described above and thus will be omitted.

The light source is located on the light receiving surface 1101 side of the light guide plate 110 and may be a white LED for emitting white light. However, in order to realize higher color reproducibility, it is preferable to use an RGB LED.

The present application also relates to a display device including the backlight unit 100 described above.

The backlight unit 100 of the present application can be applied to various display devices known in the art such as a liquid crystal display (LCD) or an organic light emitting diode (OLED) display device, and is not particularly limited.

According to the light guide plate of the present application, it is possible to provide an organic light emitting diode or a liquid crystal display device with high color reproducibility by narrowing the wavelength line widths of red (R), green (G) and blue (B) without using expensive QD films .

1 is a diagram schematically showing a cross section of a light guide plate according to an embodiment of the present application.
2 is a diagram schematically showing a reflection surface of a light guide plate having a lattice pattern formed thereon.
Fig. 3 is a diagram schematically showing a reflection surface of a light guide plate having a dot pattern formed thereon.
4 is a diagram schematically showing a cross section of the light guide plate of the present application including the light absorbing layer of the present application.
5 is a diagram schematically showing a cross section of a light guide plate of the present application including a light reflection layer
6 is a diagram schematically showing a cross section of a light guide plate according to another embodiment of the present application.
7 is a diagram schematically showing an upper surface of a light guide plate formed only on a part of the reflection surface of the light reflection portion of the present application.
8 is a graph showing a spectrum of light reflected from a light guide plate manufactured according to Embodiment 1 of the present application.
9 is a graph showing a spectrum of light reflected from a light guide plate according to Comparative Example 1 of the present application.
10 is a graph showing a spectrum of light reflected from a light guide plate according to Comparative Example 2 of the present application.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the scope of the present application is not limited by the following description.

Production Example 1 - Preparation of First Liquid Crystal Composition Having Blue Pitch

, 4.99 parts by weight of an ultraviolet curable polymer resin (RM-257, Merck), 0.11 part by weight of a photo-curing initiator (irgacure-257), 30.95 parts by weight of chiral dopant (S-811, Merck) 5CB LC, Merck) were mixed to prepare a first liquid crystal composition having a reflection peak value at about 450 nm. In the above, parts by weight means percentage by weight (wt%).

Production Example 2 - Preparation of Second Liquid Crystal Composition Having Green Pitch

4.99 parts by weight of an ultraviolet curable polymer resin (RM-257, Merck) as a binder resin, 0.11 part by weight of a photo-curing initiator (irgacure-257), 25.32 parts by weight of chiral dopant (S-811, Merck) 5CB LC, Merck) were mixed to prepare a second liquid crystal composition having a reflection peak value at about 540 nm. In the above, parts by weight means percentage by weight (wt%).

Production Example 3 - Preparation of Third Liquid Crystal Composition Having Red Pitch

4.99 parts by weight of an ultraviolet curable polymer resin (RM-257, Merck) as a binder resin, 0.11 part by weight of a photo-curing initiator (irgacure-257), 21.42 parts by weight of chiral dopant (S-811, Merck) LC, Merck) were mixed to prepare a third liquid crystal composition having a reflection peak value at about 650 nm. In the above, parts by weight means percentage by weight (wt%).

Example 1

The third liquid crystal composition prepared in Production Example 3 was spin-coated on the reflective surface of a light guide plate having a reflective pattern formed thereon, and then cured by irradiating ultraviolet rays with an ultraviolet laser of 200 mW for 10 minutes to form a third liquid crystal layer . Then, the second liquid crystal composition prepared in Production Example 2 was coated on the third liquid crystal layer by the same method and cured to form a second liquid crystal layer having a thickness of about 30 탆. Thereafter, the first liquid crystal composition prepared in Production Example 1 was coated on the second liquid crystal layer by the same method and then cured to form a first liquid crystal layer having a thickness of about 30 탆, Of the blue phase liquid crystal layer was prepared.

After applying the light guide plate to the backlight unit, light was irradiated from the RGB LED, and the reflection spectrum of the reflected light was measured using a spectrometer. The results are shown in FIG.

Example 2

The third liquid crystal composition prepared in Production Example 3 was used in 1/3 of the reflection pattern of the reflection surface of the light guide plate on which the reflection pattern was formed and the second liquid crystal composition produced in Production Example 2 was used in 1/3 of the reflection pattern, The first liquid crystal composition prepared in Production Example 1 was coated on the remaining one-third of the pattern by electronic printing and cured by irradiating ultraviolet rays with an ultraviolet laser of 200 mW for 15 minutes so as to have a thickness of about 50 탆 The first liquid crystal part, the second liquid crystal part and the third liquid crystal part were coated with a single layer.

Comparative Example 1

A light guide plate without a light reflecting portion was prepared.

After the prepared light guide plate was applied to the backlight unit, light was irradiated from the RGB LED, and the reflection spectrum of the reflected light was measured using a spectrometer. The results are shown in FIG.

Comparative Example 2

The reflection spectrum of light reflected in the same manner as in Comparative Example 1 was measured using a spectrometer except that a QD film (Samsung Electronics) was used for the light-exiting surface of the light guide plate of Comparative Example 1, and the result is shown in Fig. . .

Measurement results: Spectral analysis of light

The reflectance spectra of the light emitted from the backlight unit manufactured in Examples and Comparative Examples were analyzed, and the results are shown in Figs. 8 to 11. Fig. As shown in the graph of Fig. 10, it can be seen that the wavelength line widths of R, G and B are very wide in the case of the comparative example 1, and in the case of the comparative example 2, The wavelength linewidths of red (R), green (G) and blue (B) are wider than those of Examples 1 and 2, It can be confirmed that the color reproducibility is poor.

100: Backlight unit
110: light guide plate
1101: Light receiving surface
1102:
1103:
120: light reflection part
121: a first liquid crystal layer of the light reflecting portion,
122: a second liquid crystal layer in the light reflection portion,
123: a third liquid crystal layer of the light reflecting portion,
1102A: first region
1102B: the second area
130: light absorbing layer
140: phase retardation film
150: light reflection layer
151: a first liquid crystal layer
152: a second liquid crystal layer
153: Third liquid crystal layer of the light reflection layer
160: Light source

Claims (19)

A light receiving surface on which light emitted from a light source is incident; A reflection area including a first area where a reflection pattern for reflecting light incident from the light receiving surface is formed and a second area where the reflection pattern is not formed; And a light output surface on which the light reflected from the reflection surface is emitted,
A first liquid crystal having a reflection peak in a wavelength range of 400 to 500 nm; A second liquid crystal having a reflection peak in a wavelength range of 500 to 600 nm; And a third liquid crystal having a reflection peak in a wavelength range of 600 to 700 nm, wherein the first liquid crystal, the second liquid crystal or the third liquid crystal comprises 50 to 99 parts by weight of the liquid crystal polymer and 1 to 50 parts by weight of the liquid crystal polymer A light guide plate comprising a light reflecting portion including a chiral dopant doped in a liquid crystal polymer and formed on part or all of the reflection surface. 2. The light guide plate according to claim 1, wherein the reflection pattern is formed on the reflection surface in a relief or depressed shape. The light-emitting device according to claim 1, wherein the light reflecting portion is formed on all of the reflecting surfaces,
Wherein the light reflection portion includes a liquid crystal layer formed on the first region and the second region of the reflection surface,
Wherein the liquid crystal layer comprises: a first liquid crystal layer including a first liquid crystal; A second liquid crystal layer including a second liquid crystal; And a third liquid crystal layer including a third liquid crystal . The light guide plate according to claim 3, further comprising a light absorbing layer formed under the light reflecting portion. The light emitting device according to claim 3, further comprising a light reflecting layer formed under the light reflecting portion,
Wherein the light reflection layer comprises: a first liquid crystal layer including a first liquid crystal; A second liquid crystal layer including a second liquid crystal; And a third liquid crystal layer including a third liquid crystal,
The stacking order of the first liquid crystal layer, the second liquid crystal layer, and the third liquid crystal layer of the light reflecting layer is the order of stacking the first liquid crystal layer, the second liquid crystal layer, and the third liquid crystal layer of the light reflection portion, . The light-emitting device according to claim 1, wherein the light reflection portion is formed on only a part of the reflection surface,
The light-
A first liquid portion formed on a part of the first region of the reflective surface and including a first liquid crystal; A second liquid portion formed in a portion of the first region where the first liquid crystal part is not formed and including a second liquid crystal; And a third liquid portion formed in a remaining portion of the first region where the first liquid crystal portion and the second liquid crystal portion are not formed, the third liquid crystal portion including a third liquid crystal. The light guide plate according to claim 6, wherein the ratio of the number of the first liquid portion, the second liquid portion, and the third liquid crystal portion is 1: 1: 1. The light guide plate according to claim 1, further comprising a phase retardation film formed on the light exit surface side of the light guide plate and having a phase delay of 1/4 of the wavelength of light reflected from the reflection surface. delete The light guide plate according to claim 1, wherein the light reflecting portion further comprises a binder resin. The light guide plate according to claim 10, wherein the binder resin is a photocurable polymer resin or a thermosetting polymer resin. The light guide plate according to claim 10, wherein the light reflection part comprises 1 to 50 parts by weight of a binder resin based on 100 parts by weight of the liquid crystal. Light source; And
A light guide plate according to any one of claims 1 to 8 and 10 to 12,
Wherein the light source is located on the light-receiving surface side of the light guide plate. A display device comprising the backlight unit of claim 13. A third liquid crystal composition including a third liquid crystal having a reflection spectrum peak in a wavelength range of 600 to 700 nm is coated and cured to form a third liquid crystal layer on the reflective surface of the light guide plate having a reflective surface on which a reflective pattern is formed ;
Coating and curing a second liquid crystal composition including a second liquid crystal having a reflection spectrum peak in a wavelength range of 500 to 600 nm on the third liquid crystal layer to form a second liquid crystal layer; And
Coating a first liquid crystal composition including a first liquid crystal having a reflection spectrum peak in a wavelength range of 400 to 500 nm on the second liquid crystal layer and curing the first liquid crystal composition to form a first liquid crystal layer . A first liquid crystal composition including a first liquid crystal having a reflection spectrum peak in a wavelength range of 400 to 500 nm is coated and cured on a part of the reflection pattern of the light guide plate having a reflection surface on which a reflection pattern is formed, Forming a part;
A second liquid crystal composition including a second liquid crystal having a reflection spectrum peak in a wavelength range of 500 to 600 nm is coated and cured on a pattern in which the first liquid crystal pattern is not formed in the reflection pattern to form a second liquid crystal portion step; And
A third liquid crystal composition including a third liquid crystal having a reflection spectrum peak in a wavelength range of 600 to 700 nm is coated and cured on the remaining part of the reflection pattern in which the first liquid crystal pattern and the second liquid crystal pattern are not formed And forming a third liquid crystal portion,
Wherein the first liquid crystal, the second liquid crystal or the third liquid crystal comprises 50 to 99 parts by weight of a liquid crystal polymer and 1 to 50 parts by weight of a chiral dopant doped in the liquid crystal polymer. 16. The method of manufacturing a light guide plate according to claim 15, wherein the coating is performed by at least one method selected from the group consisting of spin coating, blade coating, bar coating, imprinting and electronic printing. The method of manufacturing a light guide plate according to claim 16, wherein the coating is performed by electronic printing. The method of manufacturing a light guide plate according to claim 15 or 16, wherein the curing is performed by heat curing or photo-curing.

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