WO2023018111A1 - Optical film and backlight unit including same - Google Patents

Abstract

A backlight unit according to various embodiments of the present disclosure comprises a light source, a color conversion sheet for converting the color of light emitted from the light source, and at least one optical film arranged over the color conversion sheet, wherein the at least one optical film comprises: a first sheet including a first base portion, a first pattern layer including a first pattern on one surface of the first base portion, and a second pattern layer which is arranged on the other surface of the first base portion and includes a second pattern different from the first pattern; and a second sheet including a second base portion, a third pattern layer including the first pattern on one surface of the second base portion, and a fourth pattern layer which is arranged on the other surface of the second base portion and includes the second pattern, and the first sheet and the second sheet of the optical film are laminated.

Description

Optical film and backlight unit including the same

Various embodiments of the present disclosure relate to an optical film and a backlight unit including the same.

In general, a liquid crystal display (LCD) may include a backlight unit that uniformly radiates light to an entire screen of an electronic device. Depending on the position of the light source, the backlight unit is an edge type that requires a light guide plate in which the lamp is located on the side of the substrate including the display surface and converts the linear light of the lamp into surface light, and the backlight unit is located below the substrate including the display surface. It is classified as a direct type that does not require a light guide plate because of its location. Among them, the direct type backlight unit has a high light utilization efficiency, a simple configuration, and is widely used in general liquid crystal display devices because there is no limit on the size of the substrate. A general direct type backlight unit may include an optical film including a light source, a diffusion sheet, and a prism. The light emitted from the light source may be diffused through the diffusion sheet and then transmitted to the liquid crystal panel through an optical film provided thereon.

As a light source, a mini LED (light emitting diode) having advantages such as miniaturization, light weight, and/or low power consumption, and/or a liquid crystal display device using a micro LED has been actively utilized. Each mini LED or micro LED chip can constitute an individual pixel or light source, so restrictions on the size and shape of the display are eliminated, and a clearer picture quality can be realized than in the case of using a conventional light source.

Along with the miniaturization of the LED chip size, research on a backlight unit to complement the LED light characteristics is also actively progressing.

A direct type backlight unit using a mini LED or micro LED as a light source may use a diffusion sheet for converting light from a point light source into a surface light source. Since the direct backlight unit arranges the light source on a flat surface, a thick diffusion sheet is provided or a plurality of diffusion sheets are stacked to prevent the shape of the light source (eg, mini LED or micro LED) from being visible on the liquid crystal panel. can have a single structure.

According to an embodiment, a shielding sheet for shielding a hot spot, which is a phenomenon in which the shape of a light source is visually recognized on a liquid crystal panel, may be additionally or alternatively included with respect to the diffusion sheet.

Since the shielding sheet (and/or the diffusion sheet) needs to be thick to a certain extent in order to have shielding performance that prevents the shape of a light source from being visible on the liquid crystal panel, thinning of the liquid crystal display may be restricted. On the other hand, if the thickness of the shielding sheet is excessively thick, this may cause a problem in that the luminance of the liquid crystal display device is greatly reduced. As described above, in the backlight unit including the shielding sheet, the thickness of the shielding sheet may be related to shielding performance and luminance performance, where the shielding performance and the luminance performance are in a trade-off relationship with each other. There may be.

The present invention, through various embodiments, provides an optical film for a liquid crystal display device having excellent performance in preventing the shape of a light source from being recognized on a liquid crystal panel (hereinafter referred to as 'shielding performance') without using a thick diffusion sheet. want to provide

A backlight unit according to various embodiments of the present disclosure may include a light source; a color conversion sheet for converting the color of the light emitted from the light source; and at least one optical film disposed over the color conversion sheet, wherein the at least one optical film comprises: a first base portion; a first pattern layer including a first pattern on one surface of the first base part; and a second pattern layer disposed on the other surface of the first base portion and including a second pattern different from the first pattern; a first sheet including; and a second base portion; a third pattern layer including the first pattern on one side of the second base part; and a second sheet comprising a fourth pattern layer disposed on the other surface of the second base portion and including the second pattern, wherein the first sheet and the second sheet of the optical film are laminated ( lamination) may include a backlight unit characterized in that.

According to various embodiments of the present disclosure, by providing a shielding sheet in which a plurality of films are laminated, an optical film having excellent shielding performance and a backlight unit including the same may be provided without using a thick sheet.

Effects obtainable in the present disclosure are not limited to the effects mentioned above, and other effects not mentioned may be clearly understood by those skilled in the art from the description below. will be.

1 is a diagram illustrating a liquid crystal display device including a diffusion sheet according to an exemplary embodiment.

2 is a view illustrating a liquid crystal display device including a backlight unit provided with a shielding sheet in which a plurality of films are laminated according to various embodiments of the present disclosure.

3 is a side view illustrating a shielding sheet in which a plurality of films are laminated according to various embodiments of the present disclosure.

4 is a perspective view illustrating a shielding sheet in which a plurality of films are laminated according to various embodiments of the present disclosure.

5 is a diagram illustrating one sheet included in an optical film according to various embodiments of the present disclosure.

6A is a diagram illustrating illuminance, beam width, standard deviation, and luminance values for each prism apex angle, according to various embodiments of the present disclosure.

6B is a graph showing a standard deviation for each prism vertex angle, according to various embodiments of the present disclosure.

7A is a diagram illustrating illuminance, beam width, standard deviation, and luminance values for each prism pitch interval, according to various embodiments of the present disclosure.

7B is a graph showing a standard deviation for each prism pitch interval, according to various embodiments of the present disclosure.

FIG. 8A is a diagram illustrating illuminance, beam width, standard deviation, and luminance values for each vertex angle of a pyramid, according to various embodiments of the present disclosure.

8B is a graph showing standard deviations for each vertex angle of a pyramid, according to various embodiments of the present disclosure.

9A is a diagram illustrating illuminance, beam width, standard deviation, and luminance values for each pyramid pitch interval, according to various embodiments of the present disclosure.

9B is a graph showing a standard deviation for each pyramid pitch interval, according to various embodiments of the present disclosure.

Various embodiments of this document and terms used therein are not intended to limit the technical features described in this document to specific embodiments, but should be understood to include various modifications, equivalents, or substitutes of the embodiments. In connection with the description of the drawings, like reference numbers may be used for like or related elements. The singular form of a noun corresponding to an item may include one item or a plurality of items, unless the relevant context clearly dictates otherwise.

According to various embodiments, each component (eg, film or sheet) of the above-described components may include a single object or a plurality of objects, and some of the plurality of objects may be separately disposed in other components. there is. According to various embodiments, one or more components or operations among the aforementioned corresponding components may be omitted, or one or more other components or operations may be added. Alternatively or additionally, a plurality of components (eg films or sheets) may be integrated into one component. In this case, the integrated component may perform one or more functions of each of the plurality of components identically or similarly to those performed by a corresponding component of the plurality of components prior to the integration. .

An embodiment will be described with reference to the accompanying drawings. In describing the present embodiment, the same name and the same reference numeral are used for the same configuration, and additional description thereof will be omitted. In addition, in describing the embodiments of the present invention, the same names and the same reference numerals are used for components having the same functions, but it is revealed in advance that they are not substantially the same as those of the prior art.

According to various embodiments, terms such as "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or It should be understood that the above does not preclude the possibility of the presence or addition of other features, numbers, steps, operations, components, parts, or combinations thereof.

1 is a diagram illustrating a liquid crystal display device including a diffusion sheet according to an exemplary embodiment.

Referring to FIG. 1 , a liquid crystal display (or liquid crystal display (LCD) device) 1 may include a backlight unit 10 and a liquid crystal panel 20 . According to various embodiments, the backlight unit 10 may be disposed toward the rear surface (the surface facing the -Z direction) of the liquid crystal panel 20 to emit light to the liquid crystal panel 20 . The backlight unit 10 may include a substrate 11 including a light source 11a, a color conversion sheet 13, diffusion sheets 14 and 17, and prism sheets 15 and 16. The backlight unit 10 may further include a reflective polarizing sheet, although not shown in the drawings.

According to various embodiments, the light source 11a is configured to emit light to the rear surface of the liquid crystal panel 20 and may be disposed on one surface of the substrate 11 . The light source 11a may correspond to a light emitting diode (LED, hereinafter referred to as LED). The light source 11a may include, for example, a plurality of LED chips 11a emitting light. Depending on the size of the LED chip, LEDs are classified into large LED (chip size: 1,000 ㎛ or more), middle LED (chip size: 300 - 500 ㎛), and small LED (chip size: 200 μm). -300 μm), mini LED (chip size 100 - 200 μm), and micro LED (chip size: 100 μm or less). Here, the LED may include a material such as InGaN or GaN. Light emitted from the light source 11a may be emitted toward the direction (Z direction) of the liquid crystal panel 20 . Light emitted from the light source 11a may pass through the color conversion sheet 13 and be incident to the diffusion sheet 14 .

According to various embodiments, a reflective sheet 12 may be formed on the surface of the substrate 11 . The reflective sheet 12 may include a material such as BaSo4, TiO2, CaCo3, SiO2, and Ca3(So4)2, or may include a material such as Ag, and may include a substrate 11 between the light sources 11a and the light sources 11a. ) can be applied or coated on. The reflective sheet 12 reflects the light emitted from the light source 11a toward the substrate 11 by interfacial reflection while passing through the color conversion sheet 13, the diffusion sheets 14 and 17, and the prism sheets 15 and 16. It may play a role of reflecting the light back to the divergence direction of the light. Through this, loss of light can be minimized. That is, the reflective sheet 12 may perform light recycling.

According to various embodiments, the color conversion sheet 13 may convert the color of light emitted from the light source 11a. For example, the light of the mini LED or micro LED may be blue light (450 nm). In this case, the blue light needs to be converted to white light. The color conversion sheet 13 transmits the blue light emitted from the light source 11a and simultaneously converts the blue light into white light.

According to various embodiments, the diffusion sheets 14 and 17 may uniformly disperse light incident from the color conversion sheet 13 . The diffusion sheets 14 and 17 include a curable resin (eg, at least one of urethane acrylate, epoxy acrylate, ester acrylate, ester acrylate, and a radical-generating monomer) to which light diffusion agent beads are added. (either alone or mixed) solution may be applied to induce light diffusion by means of optical powder beads. In addition, the diffusion sheets 14 and 17 may have protrusion patterns (or protrusions) of uniform or non-uniform size (eg, spherical shape) to promote light diffusion.

According to various embodiments, the diffusion sheets 14 and 17 may include a lower diffusion sheet 14 and an upper diffusion sheet 17 . The lower diffusion sheet 14 may be disposed between the color conversion sheet 13 and the prism sheet 15, and the upper diffusion sheet 17 may be disposed between the prism sheet 16 and the liquid crystal panel 20. . If the back light unit 10 further includes a reflective polarizing sheet, the image diffusion sheet 17 may be disposed between the prism sheet 16 and the reflective polarizing sheet.

According to various embodiments, the prism sheets 15 and 16 may condense incident light using an optical pattern formed on a surface thereof and then emit the incident light to the liquid crystal panel 20 . The prism sheets 15 and 16 may include a light-transmitting base film and a prism pattern layer formed on an upper surface (a surface facing the +Z-axis direction) of the base film. The prism pattern layer may be formed as an optical pattern layer in the form of a triangular array in which inclined surfaces (eg, 45° inclined surfaces) of a predetermined angle are formed in order to improve luminance in a plane direction. The prism patterns of the prism pattern layer may have a triangular prism shape, and one surface of the triangular prism may face the base film.

According to one embodiment, the prism sheets 15 and 16 may include a first prism sheet 15 and a second prism sheet 16 to form a composite prism sheet structure. Here, the second prism sheet 16 may be disposed to overlap the upper surface of the first prism sheet 15 . In the first prism sheet 15 , a plurality of first prism patterns may be arranged in parallel with each other. Each of the first prism patterns may have a structure extending in one direction. For example, the vertex lines 15a of each of the first prism patterns may extend toward the X-axis direction. Similarly, in the second prism sheet 16, a plurality of second prism patterns may also be arranged parallel to each other. Each of the second prism patterns may have a structure extending in one direction. For example, the vertex lines 16a of each of the second prism patterns may extend in a direction perpendicular to the X-axis and the Z-axis (hereinafter referred to as 'Y-axis'). Here, the extension directions of the first prism patterns and the extension directions of the second prism patterns are illustrated as being directed toward the X axis and the Y axis for convenience of description. However, it is not limited to the illustrated embodiment, and may be directed in directions other than the X axis or the Y axis.

According to various embodiments, a reflective polarizing sheet (not shown) is provided on the prism sheets 15 and 16 and the image diffusion sheet 17 to condense light from the prism sheets 15 and 16 and diffuse by the image diffusion sheet. It can serve to transmit some polarized light and reflect other polarized light downward.

According to various embodiments, the liquid crystal panel 20 may refract light emitted from the light source 11a in a predetermined pattern according to an electrical signal. The refracted light may pass through a color filter and a polarization filter disposed on the front surface of the liquid crystal panel 20 to form a screen.

2 is a view illustrating a liquid crystal display device including a backlight unit provided with a shielding sheet in which a plurality of films are laminated according to various embodiments of the present disclosure.

Referring to FIG. 2 , a liquid crystal display device (or liquid crystal display (LCD) device) 1 according to an embodiment of the present disclosure includes a backlight unit 10 and a liquid crystal panel 20, and a backlight unit ( 10) may include the substrate 11 including the light source 11a, the color conversion sheet 13, the optical film 100, the prism sheets 15 and 16, and the diffusion sheet 17. According to an embodiment, a reflective sheet 12 may be formed on one surface of the light source 11a.

According to an embodiment, in the backlight unit 10, at least one of these components (eg, the diffusion sheet 17) is omitted or one or more other components (eg, a reflective polarizing sheet (not shown)) are added. It can be. Hereinafter, descriptions of portions overlapping those of FIG. 1 will be omitted. The liquid crystal display device 1 of the present disclosure may be characterized by providing at least two optical films. Here, the at least two optical films 100 may replace the lower diffusion sheet 14 or may be provided additionally thereto. Hereinafter, in the description of the drawings of the present disclosure, it is exemplified that at least one optical film is provided on one side in place of the lower diffusion sheet 14 .

In the present disclosure, the term 'optical film' includes two shielding sheets having a first pattern on one side of a light-transmitting base film (hereinafter referred to as 'base part') and further including a second pattern on the other surface of the base part, and lamination with each other. (lamination) form. Also, in the present disclosure, at least one optical film may include two optical films as shown in FIG. 2 . However, it is not necessarily limited thereto, and may include three or more optical films in some cases. In the drawing of FIG. 2, although shown somewhat exaggerated for convenience of description, two different sheets 110 and 120 having very thin thicknesses are laminated to form the first optical film 100, and another two sheets ( 210 and 220 are shown forming the second optical film 200 .

In the present disclosure, 'lamination' may mean bonding by providing an adhesive to at least one sheet among two different sheets. The laminated type of optical film may provide a backlight unit that is thinner and has excellent shielding performance than in the case of simply stacking the optical film without being laminated.

According to various embodiments of the present disclosure, when four different shielding sheets 110, 120, 130, and 140 form two optical films, the first sheet 110 and the second sheet 120 are Each base part has a thickness of 50 μm and is laminated together to form the first optical film 100, and the third sheet 210 and the fourth sheet 220 each have a base part thickness of 75 μm and are laminated together to form the first optical film 100. The film 200 may be configured. The first optical film 100 and the second optical film 200 of the present disclosure may be provided on the color conversion sheet 13 in a laminated state, replacing or additionally to the lower diffusion sheet 14 . The optical films 100 and 200 according to various embodiments of the present disclosure (hereinafter, may be referred to as 'a laminated optical film') include, for example, a first sheet 110 having a thickness of 50 μm and a second Compared to the embodiment in which the sheet 120, the third sheet 210 and the fourth sheet 220 having a thickness of 75 μm are simply laminated (hereinafter, referred to as a “non-laminated optical film”), the thickness is several μm or more While having a shape, it is possible to exhibit high rigidity and excellent shielding performance. For example, according to simulation results conducted by the applicant, the optical film in which the above-described four different shielding sheets 110, 120, 130, and 140 are not laminated has a thickness of 405 μm and a shielding degree of 2.1. Compared to what can be formed, the laminated optical film can have a thinner thickness of 402 μm and a higher shielding degree of 2.3. In addition, even in terms of luminance characteristics, the laminated optical film has 94.8% luminance, compared to 92.0% of the non-laminated optical film, and thus has excellent performance in terms of luminance.

3 is a side view illustrating a shielding sheet in which a plurality of films are laminated according to various embodiments of the present disclosure. 4 is a perspective view illustrating a shielding sheet in which a plurality of films are laminated according to various embodiments of the present disclosure.

In the present disclosure, the at least one optical film may include the first optical film 100 and the second optical film 200 .

Specifically, the first optical film 100 includes a first base portion 112; a first pattern layer 111 including a first pattern on one side of the first base part 112; And a second pattern layer 113 disposed on the other surface of the first base portion 112 and including a second pattern different from the first pattern; base portion 122; a third pattern layer 121 including the first pattern on one side of the second base part 122; and a second sheet 120 including a fourth pattern layer 123 disposed on the other surface of the second base portion and including the second pattern.

The second optical film 200 includes a third base portion 212; a fifth pattern layer 211 including a first pattern on one surface of the third base portion 212; and a sixth pattern layer 213 disposed on the other surface of the third base portion 212 and including a second pattern different from the first pattern; and a third sheet 210 including a fourth base portion. (222); a seventh pattern layer 221 including the first pattern on one side of the fourth base part 222; and a fourth sheet 220 including an eighth pattern layer 223 disposed on the other surface of the fourth base portion 222 and including the second pattern.

Here, the third base part 212 and the fourth base part 222 may be formed to have a thickness different from that of the first base part 112 and the second base part 122 . For example, as described above with reference to FIG. 2 , the third base portion 212 and the fourth base portion 222 have a thickness of 75 μm, and the first base portion 112 and the second base portion 122 have a thickness of 50 μm. may have a thickness of Accordingly, the thickness of the second optical film 200 may be thicker than that of the first optical film 100 as a whole. If the thickness of the base part is thin, it may be damaged by the heat generated from the light source 11a, and a phenomenon in which the sheet bulges unevenly (seat woom phenomenon) may occur. Therefore, according to an embodiment of the present disclosure, the thickness of the second optical film 200 close to the light source 11a is formed to be thicker than the thickness of the first optical film 100 to prevent the sheet from swelling unevenly. and improve product reliability. According to an embodiment, the shielding performance of the first optical film 100 may be improved by using the refractive index of each layer. For example, in the first optical film 100 , the refractive index of the first pattern layer 111 may be smaller than the refractive index of the second pattern layer 113 . Also, the refractive index of the third pattern layer 121 may be greater than that of the fourth pattern layer 123 . Shielding performance can be improved by forming the refractive index of the third pattern layer 121, which is a light exit layer, higher than the refractive index of the fourth pattern layer 123, which is a light incident layer, to increase the bending angle of light. However, the first pattern layer 111, which is the uppermost layer, corresponds to the light emission layer, but the refractive index of the first pattern layer 111 is smaller than that of the second pattern layer 113 in order to prevent a significant decrease in luminance. can do. Specifically, when the refractive indices of the first base portion 112 and the second base portion 122 are formed at approximately 1.60 to 1.70, the refractive index of the first pattern layer 111 is formed at approximately 1.45 to 1.50, respectively. The refractive index of the second pattern layer 113 may be formed to be approximately 1.50 to 1.55 greater than the refractive index of the first pattern layer 113 . Also, the refractive index of the third pattern layer 121 may be approximately 1.65 to 1.70, and the refractive index of the fourth pattern layer 123 may be approximately 1.45 to 1.50.

According to an embodiment, in the case of including the first optical film 100 and the second optical film 200 as at least one optical film, the first optical film 100 and the second optical film 100 are separated by using the refractive index of each layer. 2 The shielding performance of the optical film 200 can be improved. For example, in the first optical film 100 , the refractive index of the first pattern layer 111 may be smaller than the refractive index of the second pattern layer 113 . Also, the refractive index of the third pattern layer 121 may be greater than that of the fourth pattern layer 123 . In the second optical film 200, the refractive index of the fifth pattern layer 211 is greater than that of the sixth pattern layer 213, and the refractive index of the seventh pattern layer 221 is that of the eighth pattern layer 223. It may be formed larger than the refractive index. The refractive indices of the third pattern layer 121, the fifth pattern layer 211, and the seventh pattern layer 221 as the light exiting layer are measured in the fourth pattern layer 123, the sixth pattern layer 213, and Shielding performance can be improved by forming the refractive index higher than the refractive index of the eighth pattern layer 223 to increase the bending angle of light. However, the first pattern layer 111, which is the uppermost layer, corresponds to the light emission layer, but the refractive index of the first pattern layer 111 is smaller than that of the second pattern layer 113 in order to prevent a significant decrease in luminance. can do. For example, when the refractive indices of the first base portion 112 and the second base portion 122 of the first optical film 100 are approximately 1.60 to 1.70, the refractive indices of the first pattern layer 111 are respectively It is formed to be about 1.45 to 1.50, and the refractive index of the second pattern layer 113 may be formed to be about 1.50 to 1.55 greater than the refractive index of the first pattern layer 113 . Also, the refractive index of the third pattern layer 121 may be approximately 1.65 to 1.70, and the refractive index of the fourth pattern layer 123 may be approximately 1.45 to 1.50. The second optical film 200 has a refractive index of about 1.65 to 1.70 when the refractive index of the third base part 212 and the fourth base part 222 is about 1.60 to about 1.70. , and the refractive index of the sixth pattern layer 213 may be formed to be approximately 1.50 to 1.55. The seventh pattern layer 221 may have a refractive index of about 1.65 to 1.70, and the eighth pattern layer 223 may have a refractive index of about 1.45 to 1.50. Except for the sheet including the light exit layer (eg, the first pattern layer 111) forming the uppermost layer, the remaining sheet portions are formed such that the light exit layer has a higher refractive index than the light entry layer, thereby improving shielding performance.

5 is a diagram illustrating one sheet included in an optical film according to various embodiments of the present disclosure.

According to an embodiment, as one shielding sheet included in the optical film, the first sheet 110 of the first optical film 100 may be taken as an example, and the description of the first sheet 110 is the rest. It may also apply to other sheets (the second sheet 120, the third sheet 210, and the fourth sheet 220).

According to various embodiments, one shielding sheet 110 includes a first base portion 112, a first pattern layer 111 including a first pattern disposed on one surface of the base portion 112, and a base It may be composed of a second pattern layer 113 including a second pattern disposed on the other surface of the portion 112 . A first pattern layer 111 may be disposed on the surface of the base portion 112 facing the +Z-axis direction, and a second pattern layer 113 may be disposed on the surface of the base portion 112 facing the -Z-axis direction. there is.

According to one embodiment, the base portion 112 may be configured to support the first pattern layer 111 and/or the second pattern layer 113 . For example, the base portion 112 may be made of a transparent material capable of transmitting light, such as polycarbonate, polysulfone, polyacrylate, or polystyrene. )-based, polyvinyl chloride-based, polyvinyl alcohol-based, polynorbornene-based, and polyester-based materials. For example, the base part 112 may be made of at least one of polyethylene terephthalate and polyethylene naphthalate.

According to various embodiments, the first pattern layer 111 may include a plurality of prism patterns having a pattern direction parallel to a first direction (eg, A direction). A cross section of each of the plurality of prism patterns may be a triangle. Each of the plurality of prism patterns may be designed to have a gradually decreasing size toward the +Z axis.

According to various embodiments, the second pattern layer 113 has a plurality of rows in a second direction (eg, B direction), and a plurality of rows in a third direction (eg, B' direction) perpendicular to the second direction. A plurality of pyramid patterns having columns may be included. A cross section of each of the plurality of pyramid patterns may have a triangular or trapezoidal shape. The plurality of pyramid patterns may be designed as intaglio patterns when viewed from below the second pattern layer 113 (when viewed along the +Z axis). According to an embodiment, the second direction (eg, B direction) may be directed in a different direction from the first direction (eg, A direction). According to an embodiment, an angle φ formed between the second direction (eg, B direction) and the first direction (eg, A direction) may be formed to have -5˚ to +5˚. It is possible to prevent moire from occurring by making the second direction (eg, B direction) form -5˚ to +5˚ with the first direction (eg, A direction). Each of the plurality of pyramid patterns is formed in a negative shape and may be designed to gradually increase in size toward the -Z axis.

According to one embodiment, the thickness of the base portion 112 may be, for example, about 50 μm to about 75 μm. However, the thickness of the base film 112 is not limited to the above example, and may be variously designed and changed to a thickness suitable for supporting the first pattern layer 111 and the second pattern layer 113 .

The first shielding sheet 110 according to the present disclosure includes pattern layers (first pattern layer 111 and second pattern layer 113) on one side and the other side, that is, on both sides of the base portion 112, respectively. , it is possible to increase the effect of reducing light interference and color non-uniformity together with the light diffusion effect. According to one embodiment, the first pattern layer 111 and the second pattern layer 113 are coated with a UV (ultra violet) curable resin solution on one surface (or other surface) of the base portion 112 and irradiated with light. By curing, micropatterning can be implemented.

According to various embodiments, in relation to the light diffusion effect, light incident on the second pattern layer 113 may be diffused through a plurality of pyramid patterns formed on the second pattern layer 113 . The second pattern layer 113 may transmit light in a divergence direction (Z direction) of light emitted from the light source 11a. In this process, loss of light and decrease in luminance can be minimized due to refracted light refracted on the interface of the pyramid pattern and reflected light due to interface reflection. The pyramid patterns formed on the second pattern layer 1413 may include a plurality of (for example, M Х N) pyramids, and have M rows and N pyramids overlapping at least partially with the light source 11a formed on the substrate 11. A pyramid pattern having eight columns may be formed.

According to various embodiments, the shielding sheet 110 includes a first pattern layer 111 formed with a prism pattern having a predetermined height (or thickness) (a) and a pitch (b), and a predetermined height (or thickness) (c). ) and a second pattern layer 113 on which a pyramid pattern having a pitch d is formed.

According to one embodiment, in the first pattern layer 111, the height (a) and pitch (b) of the prism pattern may be defined based on the first vertex angle (θ1). Here, the first vertex angle θ1 may be defined as an angle between two facing surfaces among three surfaces forming a prism pattern having a triangular cross section. For example, the first vertex angle θ1 may be defined within a range of 70° to 120°. Also, the height (a) and pitch (b) of the prism pattern having a triangular cross section may be defined according to a ratio based on the first vertex angle (θ1). For example, when the first apex angle θ1 is 90°, the ratio of the height a and the pitch b of the prism pattern may be defined as 1:2. For example, the height (a) of the prism pattern may be about 5 to about 35 μm, and the pitch (b) of the prism pattern may be about 10 to about 70 μm. More specifically, it may be preferable that the height (a) of the prism pattern is approximately 25 μm and the pitch (b) of the prism pattern is approximately 50 μm.

According to another embodiment, in the second pattern layer 113, the height (c) and pitch (d) of the pyramid pattern may be defined based on the second vertex angle (θ2). Here, the second apex angle θ2 may be defined as an angle between two facing surfaces among four surfaces forming a pyramid pattern having a trapezoidal cross section. For example, the second vertex angle θ2 may be defined within a range of 90° to 150°. Within a specified range, as the apex angle of the pyramid pattern increases, the diffusivity of light incident on the shielding sheet 110 may further decrease. When the apex angle decreases, the diffusivity of light increases and luminance loss may increase. In addition, the height (c) and pitch (d) of the pyramid pattern having a trapezoidal cross section may be defined according to a ratio based on the second apex angle (θ2). For example, when the apex angle is 130°, the ratio of the height c to the pitch d of the pyramid pattern may be defined as 1:4. For example, the pyramid pattern may have a height (c) of about 5 μm to about 15 μm, and a pyramid pattern pitch (d) of about 20 μm to 60 μm. More specifically, it is preferable that the height (a) of the pyramid pattern is approximately 10 μm and the pitch (b) of the prism pattern is approximately 40 μm. A plurality of pyramid patterns having such a height (c) and pitch (d) may be regularly arranged in the lower portion of the shielding sheet 110 . The plurality of pyramid patterns correspond 1:1 to the light source (eg, the light source 11a of FIG. 3) formed on the substrate (eg, the substrate 11 of FIG. 3), or are arranged in an overlapping manner at least partially, so that the light source Since the emitted point light source is diffused into a surface light source, and the light of the light source 11a is light-separated (or light-diffused) by the diffusion action of the optical film 100, hot spot visibility (HSV) due to light concentration this may be reduced.

6A is a diagram illustrating illuminance, beam width, standard deviation, and luminance values for each prism apex angle, according to various embodiments of the present disclosure. 6B is a graph showing a standard deviation for each prism vertex angle, according to various embodiments of the present disclosure.

6A and 6B, the second vertex angle θ2 of the pyramid pattern of the second pattern layer 113 is fixed, and the first vertex angle θ1 of the prism pattern of the first pattern layer 111 is In case of variable, it is possible to check the values of illuminance, beam width, standard deviation and luminance. In drawings according to various embodiments of the present disclosure including FIG. 6A , the beam width may mean a spread area of light passing through a shielding sheet based on the light source LED. Since light is light-separated (or light-diffused) as the beam width increases, hot spot visibility (HSV) due to light concentration is improved, and thus, it can be said that optical characteristics are excellent. In drawings according to various embodiments of the present disclosure, including FIG. 6A , the standard deviation is an index representing uniformity of light distribution, and a higher value indicates a greater deviation of light distribution. If the deviation of the light distribution (hereinafter, referred to as 'standard deviation') is large, it can be said that the degree of shielding is reduced as the difference between a bright place and a dark place becomes clear, and thus the light characteristics are deteriorated.

According to various embodiments, the second vertex angle θ2 of the pyramid pattern of the second pattern layer 113 is fixed to about 130° and the first vertex angle θ1 of the prism pattern of the first pattern layer 111 is The beam width and standard deviation were measured when it varied from about 70° to about 120°.

6a and 6b together, when the first apex angle θ1 of the prism pattern is 70°, the beam width is 2.77 mm, 80°, 3.85 mm, and 90°, respectively, the beam width is 3.92 mm. , at 100 °, the beam width is 2.83 mm, at 110 °, the beam width is 2.41 mm, at 120 °, the beam width is 2.71 mm, and it can be seen that the beam width shows the maximum value at 90 °. In addition, it can be seen that the shielding performance deteriorates when the apex angle is larger based on 90 °.

On the other hand, when the first apex angle (θ1) of the prism pattern is 70°, the standard deviation is 4256.8, when it is 80°, the standard deviation is 3593.2, when it is 90°, the standard deviation is 2660.8, and when it is 100°, the standard deviation is 3293.0, 110 In the case of °, the standard deviation is 4385.2, in the case of 120 °, the standard deviation is 5220.0, and it can be seen that the standard deviation value represents the minimum value at 90 °. In addition, it can be seen that when the apex angle is larger based on 90 °, the standard deviation value becomes larger and the shielding performance deteriorates.

Referring to FIGS. 6A and 6B , it can be seen that the case where the apex angle of the prism is 90° while the apex angle of the pyramid pattern is fixed at 130° has the best optical performance in terms of shielding performance and standard deviation. According to various embodiments of the present disclosure, it is possible to set the apex angle of a preferred prism pattern based on the crossing of the diagram for the beam width and the diagram for the standard deviation. Accordingly, referring to FIG. 6B, various embodiments of the present disclosure According to examples, the prism pattern may be formed to have an apex angle of 80° to 100°, which is a range including the 90° apex angle of the prism having the best optical performance.

7A is a diagram showing illuminance, beam width, standard deviation, and luminance values for each prism pitch interval, according to various embodiments of the present disclosure; FIG. 7B is a standard deviation for each prism pitch interval, according to various embodiments of the present disclosure; is a graph that represents

Referring to FIGS. 7A and 7B , in a state where the second apex angle θ2 of the pyramid pattern of the second pattern layer 113 and the first apex angle θ1 of the prism pattern of the first pattern layer 111 are fixed, In the case of varying the pitch of the prism pattern of the first pattern layer 111, the illuminance, beam width, standard deviation, and luminance values may be checked.

According to various embodiments, the second vertex angle θ2 of the pyramid pattern of the second pattern layer 113 is fixed to about 130° and the first vertex angle θ1 of the prism pattern of the first pattern layer 111 is The beam width and standard deviation were measured when the pitch interval of the prism pattern was varied from 10 μm to 90 μm while the angle was fixed at about 90°.

Referring to FIGS. 7A and 7B together, when the pitch interval of the prism pattern is 10 μm, the beam width is 4.19 mm, when the pitch interval is 30 μm, the beam width is 4.14 mm, and when the pitch interval is 50 μm, the beam width is 3.92 mm. mm, the beam width is 4.18 mm when the pitch interval is 70 μm, and the beam width is 3.96 mm when the pitch interval is 90 μm, and it can be seen that the beam width shows the minimum value at 50 μm. In addition, it can be seen that the shielding performance can be reduced when the pitch interval is larger on the basis of 30 μm.

On the other hand, when the pitch interval of the prism pattern is 10 μm, the standard deviation is 2476.2, when the pitch interval is 30 μm, the standard deviation is 2570.5, when the pitch interval is 50 μm, the standard deviation is 2660.8, and when the pitch interval is 70 μm, the standard deviation is is 2653.5 and the standard deviation is 2677.0 when the pitch interval is 90 μm.

Referring to FIGS. 7A and 7B, in a state where the apex angle of the pyramid pattern is fixed to 130° and the apex angle of the prism is fixed to 90°, the smaller the pitch interval of the prism pattern, the more excellent the shielding performance and standard deviation are. It can be confirmed that it has optical performance. According to various embodiments of the present disclosure, it is possible to set a preferred pitch interval of a prism pattern based on the intersection of a diagram for beam width and a diagram for standard deviation. Referring to FIG. 7B, various embodiments of the present disclosure According to examples, it may be preferable that the prism pattern is formed to have a pitch interval of 10 μm to 30 μm.

FIG. 8A is a diagram illustrating illuminance, beam width, standard deviation, and luminance values for each vertex angle of a pyramid, according to various embodiments of the present disclosure. 8B is a graph showing standard deviations for each vertex angle of a pyramid, according to various embodiments of the present disclosure.

8A and 8B, when the first vertex angle θ1 of the first pattern layer 111 is fixed and the second vertex angle θ2 of the pyramid pattern of the second pattern layer 113 is variable. In, it is possible to check the illuminance, beam width, standard deviation and luminance values.

According to various embodiments, the first vertex angle θ1 of the prism pattern of the first pattern layer 111 is fixed to 90°, and the second vertex angle θ2 of the pyramid pattern of the second pattern layer 113 is The beam width and standard deviation when varying from about 90° to about 150° were measured.

Referring to FIGS. 8A and 8B together, when the second vertex angle θ2 of the pyramid pattern is 90°, the beam width is 3.00 mm, 100°, 3.17 mm, and 110°, the beam width is 3.48 mm. , for 120° the beam width is 4.25 mm, for 130° the beam width is 4.33 mm, for 140° the beam width is 4.50 mm. In the case of 150 °, the beam width is 3.75 mm, and it can be seen that the beam width shows the maximum value at 140 °. In addition, it can be seen that the shielding performance deteriorates when the apex angle is larger based on 140 °.

On the other hand, when the second apex angle (θ2) of the pyramid pattern is 90°, the standard deviation is 5870.9, 100°, the standard deviation is 5183.7, 110°, the standard deviation is 4382.3, and 120°, the standard deviation is 3191.0, 130 In the case of °, the standard deviation is 2420.2, in the case of 140 °, the standard deviation is 2199.5, and in the case of 150 °, the standard deviation is 2177.5.

Referring to FIGS. 8A and 8B , it can be seen that the case where the apex angle of the pyramid pattern is 140° while the apex angle of the prism pattern is fixed at 90° has the best optical performance in terms of shielding performance and standard deviation. there is. According to various embodiments of the present disclosure, a preferred apex angle of a pyramid pattern may be set based on a cross between a diagram for beam width and a diagram for standard deviation. However, referring again to FIGS. 8A and 8B, since the beam width rapidly decreases at the apex angle of the pyramid pattern greater than 140 °, 120 ° to 140 ° can be set as the preferred apex angle range of the pyramid pattern. .

9A is a diagram illustrating illuminance, beam width, standard deviation, and luminance values for each pyramid pitch interval, according to various embodiments of the present disclosure. 9B is a graph showing a standard deviation for each pyramid pitch interval, according to various embodiments of the present disclosure.

9A and 9B, in a state in which the second vertex angle θ2 of the pyramid pattern of the second pattern layer 113 and the first vertex angle θ1 of the prism pattern of the first pattern layer 111 are fixed In the case of varying the pitch of the pyramid pattern of the second pattern layer 113, the illuminance, beam width, standard deviation, and luminance values can be checked.

According to various embodiments, the second vertex angle θ2 of the pyramid pattern of the second pattern layer 113 is fixed to about 130° and the first vertex angle θ1 of the prism pattern of the first pattern layer 111 is The beam width and standard deviation were measured when the pitch interval of the pyramid pattern was varied from 40 μm to 100 μm with the angle fixed at about 90°.

Referring to FIGS. 9A and 9B together, when the pitch interval of the pyramid pattern is 40 μm, the beam width is 3.77 mm, when the pitch interval is 60 μm, the beam width is 3.60 mm, and when the pitch interval is 80 μm, the beam width is 3.49 mm. mm, when the pitch interval is 100 μm, the beam width is 3.23 mm, and it can be seen that the shielding performance may deteriorate as the pitch interval of the pyramid pattern widens.

On the other hand, when the pitch interval of the prism pattern is 40 μm, the standard deviation is 2870.8, when the pitch interval is 60 μm, the standard deviation is 2875.1, when the pitch interval is 80 μm, the standard deviation is 2973.1, and when the pitch interval is 100 μm, the standard deviation is is 3362.2, it can be seen that the standard deviation value gradually increases as the pitch interval increases, and the maximum value appears from around 100 μm.

Referring to FIGS. 9A and 9B, in a state in which the apex angle of the pyramid pattern is fixed at 130° and the apex angle of the prism is fixed at 90°, the smaller the pitch interval of the pyramid pattern, the better the shielding performance and standard deviation. It can be confirmed that it has optical performance. According to various embodiments of the present disclosure, it is possible to set a preferred pitch interval of a pyramid pattern based on the intersection of a diagram for beam width and a diagram for standard deviation. Accordingly, referring to FIG. 9B, various embodiments of the present disclosure According to examples, the pyramid pattern may be formed to have a pitch interval of 40 μm to 80 μm.

The optical film of various embodiments of the present disclosure described above and the backlight unit including the same are not limited to the above-described embodiments and drawings, and various substitutions, modifications, and changes are possible within the technical scope of the present disclosure. It will be clear to those skilled in the art to which it pertains.

Claims (15)

In the backlight unit, light source; a color conversion sheet for converting the color of the light emitted from the light source; and at least one optical film disposed over the color conversion sheet; The at least one optical film, a first base portion; a first pattern layer including a first pattern on one surface of the first base part; and a second pattern layer disposed on the other surface of the first base portion and including a second pattern different from the first pattern; and a second base part; a third pattern layer including the first pattern on one side of the second base part; and a second sheet including a fourth pattern layer disposed on the other side of the second base portion and including the second pattern, The backlight unit, characterized in that the first sheet and the second sheet of the optical film are laminated (lamination). According to claim 1, The backlight unit of claim 1 , wherein the first pattern includes a prism pattern disposed parallel to a first direction. According to claim 2, The second pattern includes a pyramid pattern having a plurality of rows in a second direction and a plurality of columns in a third direction perpendicular to the second direction. According to claim 3, The second pattern is a concave pyramid pattern formed by etching the other surfaces of the first base part and the second base part. According to claim 3, The backlight unit of claim 1 , wherein the second direction has an angle of -5° to +5° with the first direction. According to claim 3, The prism pattern forms a first vertex angle defined by an angle between two facing surfaces among three surfaces of a triangular cross-sectional shape, The backlight unit of claim 1 , wherein the first apex angle is 80° to 100°. According to claim 1, The thickness of the first pattern is 5 μm to 35 μm, The pitch interval of the first pattern is 10 μm to 70 μm. According to claim 1, The second pattern is a pyramid pattern, forming a second vertex angle defined by an angle between two facing surfaces among the four faces of the pyramid shape, The second vertex angle is 120˚ to 140˚. According to claim 1, The thickness of the second pattern is 5 μm to 15 μm, and the pitch interval of the second pattern is 20 μm to 60 μm. According to claim 1, The refractive index of the first pattern layer is smaller than the refractive index of the second pattern layer, The refractive index of the third pattern layer is greater than the refractive index of the fourth pattern layer backlight unit. According to claim 1, The optical film, a first base portion; a first pattern layer including a first pattern on one surface of the first base part; and a second pattern layer disposed on the other surface of the first base portion and including a second pattern different from the first pattern; a first sheet including; and a second base portion; a third pattern layer including the first pattern on one side of the second base part; and a fourth pattern layer disposed on the other surface of the second base portion and including the second pattern; a second sheet including a first optical film; and a third base part; a fifth pattern layer including a first pattern on one side of the third base part; and a sixth pattern layer disposed on the other surface of the third base portion and including a second pattern different from the first pattern; a third sheet including; and a fourth base portion; a seventh pattern layer including the first pattern on one surface of the fourth base part; and a fourth sheet including an eighth pattern layer disposed on the other side of the fourth base portion and including the second pattern, and including a second optical film stacked with the first optical film. unit. According to claim 11, The backlight unit of claim 1 , wherein the third base part and the fourth base part have different thicknesses from those of the first base part and the second base part. According to claim 12, The backlight unit of claim 1 , wherein the third base part and the fourth base part have a greater thickness than the first base part and the second base part. According to claim 11, Further comprising a prism sheet disposed on the optical film, The backlight unit of claim 1 , wherein the prism sheet includes a first prism sheet and a second prism sheet having prism patterns arranged in different directions. According to claim 11, The refractive index of the first pattern layer is smaller than the refractive index of the second pattern layer, The refractive index of the third pattern layer is greater than the refractive index of the fourth pattern layer, The refractive index of the fifth pattern layer is greater than the refractive index of the sixth pattern layer, The refractive index of the seventh pattern layer is greater than the refractive index of the eighth pattern layer backlight unit.

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