Patent ID: 12222597

DETAILED DESCRIPTION

Various embodiments and terms used in the specification are not intended to limit the technical features described in the specification to specific embodiments, but it should be understood to include various modifications, equivalents, or substitutions of the embodiments. In connection with the description of the drawings, similar reference numerals may be used for similar or related components. The singular form of the noun corresponding to the item may include one or more of the elements unless the relevant context clearly dictates otherwise.

According to various embodiments, each component (e.g., a module or a program) of the above-described components may include a singular or a plurality of entities, and some of the plurality of entities may be separately disposed in other components. According to various embodiments, one or more components or operations among the above-described corresponding components may be omitted, or one or more other components or operations may be added. Alternatively, or additionally, a plurality of components (e.g., a module or a program) may be integrated into one component. In this case, the integrated component may perform one or more functions of each component of the plurality of components identically or similarly to those performed by the corresponding component among the plurality of components prior to the integration. According to various embodiments, the function performed by a module, program, or other component are executed sequentially, in parallel, iteratively, or heuristically, or one or more of the actions are executed in a different order or are omitted, or one or more other actions may be added.

Embodiments will be described with reference to the associating drawings. In describing the present embodiment, the same names and the same reference numerals are used for the same components, and an additional description thereof will be omitted. In addition, in describing the embodiment of the present invention, the same names and reference numerals are used for components having the same functions, and it is substantially not completely the same as in the prior art.

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

FIG.1is an exploded perspective view of a backlight unit according to an exemplary embodiment of the present invention.

In general, a liquid crystal display device includes a backlight unit200that provides uniform light to the entire screen unlike a conventional cathode ray tube (CRT). The backlight unit200may be provided behind the liquid crystal panel to radiate light to the liquid crystal panel. The backlight unit200may include a light source210, a reflector220, a light guide plate230, a diffusion sheet240and/or an optical film100.

According to various embodiments, the light source210may emit light. The light source210may include a light emitting unit that emits light. The light source210may emit light from a side of the light guide plate230(e.g., an X-axis direction and/or a Y-axis direction) and transmit light toward the light guide plate230. As the light emitted from the light source210is irradiated to the rear surface of the liquid crystal panel, an identifiable image may be implemented.

According to an embodiment, the light source210may contain one of a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (external electrode fluorescent lamp), and a light emitting diode (LED, hereinafter referred to as LED). According to an embodiment, the light source210is divided into an edge type and a direct type according to the arrangement configuration. The direct type is capable of split driving compared to the edge type, and thus it can implement more delicate images than the edge type.

According to an embodiment, the reflector220is disposed at the rear of the light guide plate230, and thus it reflects the light emitted from the rear of the light guide plate230and then the reflected light is incident to the light guide plate230to reduce light loss.

According to an embodiment, the light guide plate230may transform light incident from the light source210into a surface light source.

According to one embodiment, the diffusion sheet240can uniformly disperse the light incident from the light guide plate230. For example, the diffusion sheet240may cause light diffusion by light diffusion beads created by depositing a solution made of a curable resin (e.g., one or combination of at least one or more selected from urethane acrylate, epoxy acrylate, ester acrylate, and a radical generating monomer) with light diffusing agent beads added. For another example, the diffusion sheet240may have uniform or non-uniformly sized (e.g., spherical) protrusion patterns (or protrusions) to promote light diffusion.

According to an embodiment, the optical film100may include a matte layer110including a plurality of protrusions111, a first base film120disposed under the matte layer110and a light blocking pattern layer130disposed under the first base film120and including a plurality of light absorption patterns140, an adhesive layer150disposed under the light blocking pattern layer130, and a second base film160disposed under the adhesive layer150, a prism structure170disposed under the second base film160and including a plurality of prisms171.

According to an embodiment, the optical film100may include a mat layer110including a plurality of protrusions111, a first base film120disposed under the mat layer110and a light blocking pattern layer130disposed under the first base film120and including a plurality of light absorption patterns140, an adhesive layer150disposed under the light blocking pattern layer130, and a second base film160disposed under the adhesive layer150, a prism structure170disposed under the second base film160and including a plurality of prisms171.

According to an embodiment, the optical film100may condense at least a portion of light generated from the light source210. For example, the optical film100may reduce the viewing angle of the display device by condensing light heading in left and right directions (e.g., X-Y plane directions) toward a central direction (e.g., +Z direction). According to one embodiment, the optical film100may be referred to as a light control film.

A plurality of components included in the above-described backlight unit200may be combined in various ways. For example, in the backlight unit200, some of the light source210, the reflector220, the light guide plate230, and the diffusion sheet240may be omitted, the arrangement order of the components may be different, or additional components may be further included. For example, a diffusion sheet may be further included between the optical film100of the backlight unit200and the reflective polarizing sheet16. For another example, some components (e.g., the diffusion sheet240) of the backlight unit200may be excluded.

According to one embodiment, the backlight unit200may be assembled with an LCD panel (not shown) and provided for a display device.

FIG.2is a side view of a backlight unit according to an embodiment of the present invention.FIG.3is a front view of a backlight unit according to an embodiment of the present invention.

Referring toFIGS.2and3, a backlight unit200may include an optical film100, a light source210and a light guide plate230. The optical film100may include a matte layer110, a first base film120, a light blocking pattern layer130, an adhesive layer150, a second base film160, and a prism structure170. The configurations of the optical film100and the backlight unit200ofFIGS.2and3may be the same as entire or part of the configurations of the optical film100and the backlight unit200ofFIG.1.

According to various embodiments, the matte layer110may reduce a viewing angle of light passing through the matte layer110. For example, the matte layer110may include a plurality of protrusions111directed in the third direction (+Z-axis direction) to form a narrow viewing angle. According to one embodiment, the matte layer110may be disposed on the first base film120. According to one embodiment, the plurality of protrusions111of the matte layer110may enhance external shielding of the optical film100and reduce moiré visibility.

According to various embodiments, the matte layer110may implement a scattering effect with surface protrusions of a non-bead type. For example, the matte layer110may be implemented by designing a plurality of protrusions on the surface for forming the matte layer through a mold process and then replicating the protrusion shape using a UV resin.

According to various embodiments, the first base film120may support the matte layer110. According to one embodiment, the first base film120may be disposed between the matte layer110and the light blocking pattern layer130. According to one embodiment, the first base film120may be formed of a material capable of transmitting at least a portion of visible light. According to an embodiment, the first base film120may include at least one of polymer resins such as polycarbonate (PC), acrylate, and polyethylene terephthalate (PET). According to one embodiment, the first base film120may be referred to as a first light-transmitting layer.

According to various embodiments, the light blocking pattern layer130may include a plurality of light absorption patterns140. According to an embodiment, the light absorption pattern140may include a material capable of absorbing at least a portion of light. For example, the light absorption pattern140may be at least one of materials capable of absorbing light, such as carbon nanotubes (CNT), graphene, or carbon black. According to an embodiment, the light blocking pattern layer130may be referred to as a louver film or a microlouver film. For example, the light blocking pattern layer130may include a plurality of light absorption patterns140and a light transmission area131positioned between the plurality of light absorption patterns140. The plurality of light absorption patterns140and the light transmission area131may be substantially alternately arranged.

According to one embodiment, the light blocking pattern layer130may be disposed between the first base film120and the adhesive layer150. For example, the light blocking pattern layer130may include a first surface130afacing the first base film120and a second surface130bopposite to the first surface130aand facing the adhesive layer150.

According to various embodiments, the plurality of light absorption patterns140may be placed side by side in a shape corresponding to each other. For example, the light absorption pattern140may extend along the first direction (e.g., the Y-axis direction). A structure in which the light absorption pattern140extends along the first direction may be interpreted as a structure in which one light absorption pattern140is arranged substantially parallel to the first direction.

According to an embodiment, the light absorption pattern140may be disposed on the second surface130b. For example, the light absorption pattern140may include an upper surface140afacing the first surface130a, a lower surface140bdisposed on the second surface130band a side surface140cextended from the lower surface140bto the upper surface140a.

According to various embodiments, the light absorption pattern140may have a substantially trapezoidal wedge shape. According to an embodiment, a cross-sectional area of the light absorption pattern140in a width direction (e.g., an X-Y plane) may have a shape that gradually decreases in the +Z direction. For example, the first angle θ1between the side surface140cand the lower surface140bof the light absorption pattern140may be 85° to 90°. The area of the lower surface140bof the light absorption pattern140may be larger than the area of the upper surface140a. When the area of the lower surface140bof the light absorption pattern140is larger than the area of the upper surface140a, moire and light interference may be reduced.

According to various embodiments, the top surface140aof the light absorption pattern140may be spaced apart from the first surface130aof the light blocking pattern layer130. Since the light absorption pattern140is spaced apart from the first surface130aof the light blocking pattern layer130, the luminance of the cut-off viewing angle may be controlled and an improved optical film100may be provided. According to an embodiment, the first distance (d1) between the upper surface140aof the light absorption pattern140and the first surface130aof the light blocking pattern layer130can be designed to consider the amount of air bubbles generated and the amount of UV resin consumption during the manufacturing process of the optical film100. For example, the first distance (d1) may be designed to be about 50 μm or less.

According to various embodiments, the plurality of light absorption patterns140may have a first pitch (P1). For example, a distance between peaks or upper surfaces140aor a distance between valleys or lower surfaces140bof the plurality of light absorption patterns140may be referred to as a first pitch (P1). According to an embodiment, the first pitch (P1) of the plurality of light absorption patterns140may be longer than the second pitch (P2) of the plurality of prisms171. The relationship between the first pitch (P1) and the second pitch (P2) will be described in detail with reference toFIGS.6and7. According to an embodiment, the light-blocking pattern layer130may include a light-transmitting area131through which light passes positioned between the plurality of light-absorption patterns140.

According to various embodiments, the adhesive layer150may be positioned between the light blocking pattern layer130and the prism structure170. For example, the adhesive layer150may connect or combine with the light blocking pattern layer130and the second base film160. According to an embodiment, the adhesive layer150may support the plurality of light absorption patterns140of the light blocking pattern layer130. According to an embodiment, the adhesive layer150can reduce light loss due to interfacial reflection by removing air gap between the light blocking pattern layer130and the second base film160.

According to various embodiments, the second base film160may support the light blocking pattern layer130. According to one embodiment, the second base film160may be disposed between the adhesive layer150and the prism structure170. According to an embodiment, the second base film160may be formed of material capable of transmitting at least a portion of visible light. According to an embodiment, the second base film160may include at least one of polymer resins such as polycarbonate (PC), acrylate, and polyethylene terephthalate (PET). According to one embodiment, the second base film160may be referred to as a second light-transmitting layer.

According to various embodiments, the prism structure170may be disposed under the second base film160(e.g., in the −Z direction). According to one embodiment, the prism structure170may include a plurality of prisms171.

According to various embodiments, the plurality of prisms171may be disposed side by side in a shape corresponding to each other. For example, the plurality of prisms171may be extended along one direction (e.g., the X-axis direction). According to one embodiment, the plurality of light absorption patterns140may be arranged to have a designated angle with respect to the plurality of prisms171. For example, a first direction where a plurality of light absorption patterns are arranged may be inclined in a specified angular range with respect to a second direction where a plurality of prisms are arranged. According to one embodiment, the designated angular range may be 80° to 100°. According to one embodiment, the plurality of light absorption patterns140may be arranged along a direction substantially perpendicular to the plurality of prisms171. For example, the plurality of light absorption patterns140may be arranged along a first direction (e.g., Y-axis direction) and the plurality of prisms171may be arranged in a direction perpendicular (e.g., X-axis direction) to the first direction (Y-axis direction). A structure where a plurality of prisms171are extended along the second direction may be interpreted as a structure where one prism171is substantially parallel to the second direction.

According to various embodiments, the plurality of prisms171may have a second pitch (P2). For example, a distance between peaks or valleys of the plurality of prisms171may be referred to as a second pitch (P2).

According to various embodiments, the plurality of light absorption patterns140may reduce a viewing angle in a left-right direction (eg, an X-axis direction). For example, the light blocking pattern layer130may condense at least a portion of light incident from below the light blocking pattern layer130. In the present invention, focusing of light may be interpreted as condensing of light.

According to an embodiment, the plurality of prisms171may control a viewing angle in a vertical direction (e.g., a Y-axis direction). For example, the prism structure170may focus (e.g., condense) at least a portion of light incident from below the prism structure170. A viewing angle of light passing through the optical film100may be reduced by the plurality of light absorption patterns140and the plurality of prisms171. As the viewing angle is reduced, the risk of exposing of important information that a user of a small electronic device such as a smart phone does not want to expose can be reduced. According to an embodiment, the direction where the plurality of prisms171are arranged may be different from the direction where the light blocking pattern layer130is arranged. For example, the light blocking pattern layer130may be arranged along a first direction (Y-axis direction), and the plurality of prisms171may be arranged along a second direction substantially perpendicular to the first direction. For another example, the light blocking pattern layer130may be arranged along a first direction (e.g., the Y-axis direction) and the plurality of prisms171may be arranged along a second direction where the second direction is inclined at 80° to 100° with respect to the first direction. According to an embodiment, the optical film100may control viewing angles in all directions by using the light blocking pattern layer130and the plurality of prisms171. For example, the light blocking pattern layer130can control a viewing angle in the left and right directions (e.g., reducing the viewing angle) by condensing light in a left and right direction (e.g., the second direction) and the plurality of prisms171can control a viewing angle in the upward direction by condensing light in the vertical direction (e.g., the first direction (Y-axis direction)). According to one embodiment, the light path of the optical film may be referred to as a 4-way structure that changes a viewing angle in a vertical direction and a viewing angle in a left-right direction.

FIG.4is a plain view of an optical film for explaining problems of the prior art.

FIG.5is a view for explaining the difference between the optical film of the present invention and the optical film of the prior art.

FIGS.1to5, the optical film100may have higher brightness than the conventional optical film300and a short full width at half maximum (FWHM).

According to various embodiments, the optical film100may have a structure where the light blocking pattern layer130and the prism structure170are laminated. For example, the optical film100may include the adhesive layer150. The adhesive layer150may be disposed between the light blocking pattern layer130and the prism structure170to attach or connect the light blocking pattern layer130and the prism structure170.

For example, a conventional optical film300may include a louver310and a reverse prism sheet320. According to one embodiment, the louver310includes a first upper matte layer311, an upper base film312, a light blocking pattern layer313, a light absorption pattern314, an adhesive layer315, a lower base film316and a lower matte layer317. The configuration of the first upper matte layer311, the upper base film312, the light blocking pattern layer313, the light absorption pattern314and the adhesive layer315of the louver310can be entirely or partially the same as the configuration of the matte layer110, the first base film120, the light blocking pattern layer130, the light absorption pattern140and the adhesive layer150of the optical film100ofFIGS.2and3.

According to one embodiment, the reverse prism sheet320may include a second upper matte layer321, a prism base film322, a prism structure323and a prism324. The configuration of the prism base film322, the prism structure323, and the prism324of the reverse prism sheet320may be entirely or partially the same as the configuration of the second base film160, the prism structure170and the prism171of the optical film100ofFIGS.2and3.

The optical film100of the present invention may be slimmer due to a one-sheet configuration comparing to a configuration where a plurality of optical sheets are simply stacked (e.g., the optical film300ofFIG.4).

According to various embodiments, the optical film100may have a first height (h1). According to an embodiment, the first height (h1) may be changed based on the thickness of the base films120and160. For example, when the first base film120and the second base film160are PET with a thickness of about 50 μm, the first height (h1) of the optical film100may be about 270 μm. For another example, when the first base film120and the second base film160are OCF-PET having a thickness of about 80 μm, the first height (h1) of the optical film100may be about 330 μm. In the conventional optical film300in which a plurality of optical sheets are simply stacked, the louver310has a second height (h2) of about 300 μm, and the reverse prism sheet320may have a third height (h3) of about 155 μm. For example, the optical film100of the present invention may exclude some components (e.g., the lower base film316or the prism base film322) of the conventional laminated optical film300because the louver310and the reverse prism sheet320are laminated.

The optical film100of the present invention may improve the viewing angle narrowing performance and the brightness performance compared to a structure where a plurality of optical sheets are simply stacked (e.g., the optical film300ofFIG.4). According to an embodiment, referring to a conoscope image of the optical film100of the present invention, a conoscope image of the reverse prism sheet320and/or a conoscope image of the conventional optical film300, the viewing angle of the optical film100of the present invention may be the narrowest. According to one embodiment, the brightness of the optical film100of the present invention may be greater than that of the conventional optical film300, and the full width at half maximum (FWHM) may be reduced. The conoscopic image may be referred to as a captured viewing angle image using a device for observing a moving path of light.

According to various embodiments, the cut-off viewing angle brightness of the optical film100may be decreased as the refractive index of the adhesive layer is increased. According to one embodiment, the cut-off viewing angle brightness of the optical film100of the present invention may be improved over the cut-off viewing angle brightness of the conventional optical film300.

FIG.6is a chart for explaining an effect of an optical film with respect to a ratio of a first pitch to a second pitch, according to various embodiments of the present invention.FIG.7is a graph for explaining the brightness with respect to a ratio of a first pitch to a second pitch, according to various embodiments of the present invention. For example, a vertical axis ofFIG.7may mean the brightness and a horizontal axis may mean the viewing angle.

Referring toFIGS.6and7, the brightness, the full width at half maximum (FWHM), the viewing angle, and/or the light path of the optical film may be changed based on the ratio of a first pitch (e.g., the first pitch (P1) ofFIG.3) of a light absorption pattern (e.g., the light absorption pattern140ofFIG.3) and a second pitch (e.g., the second pitch (P2) inFIG.2) of a prism (e.g., the prism171ofFIG.2). According to an embodiment, as the brightness is increased, the privacy function may be decreased. For example, when the brightness is increased, the full width at half maximum (FWHM) is increased so that the privacy function may be reduced.

According to various embodiments, the optical film may have pitches (P1, P2) having a full width at half maximum (FWHM) for a privacy function while maintaining brightness for user convenience. According to an embodiment, as the length of the first pitch (P1) relative to the second pitch (P2) is increased, the brightness and full width at half maximum (FWHM) may be increased. According to an embodiment, the ratio of the first pitch (P1) to the second pitch P2may be 1.5 to 2.75. More preferably, the first pitch (P1) may be 2 to 2.5 times of the second pitch (P2). For example, the first pitch (P1) may be 27 μm to 50 μm. The second pitch (P2) may be about 18 μm. According to one embodiment, the first pitch (P1) may be about 2.15 times of the second pitch (P2).

FIG.8is a chart for explaining an effect of an optical film with respect to a relative ratio of refractive index according to various embodiments of the present invention.FIG.9is a graph for explaining the brightness of an optical film with respect to a relative ratio of refractive index according to various embodiments of the present invention. For example, a vertical axis ofFIG.9may mean the brightness and a horizontal axis may mean the viewing angle.

FIGS.8and9, the brightness, the full width at half maximum (FWHM), the viewing angle, and/or the light path of the optical film may be changed based on the ratio of a first refractive index (clear) of the light blocking pattern layer130and a second refractive index (prism) of the prism structure (e.g., the prism structure170ofFIG.2). According to an embodiment, as the brightness is increased, the full width at half maximum (FWHM) is increased so that the privacy function may be reduced. For example, the full width at half maximum (FWHM) and the brightness may have a trade-off relationship.

According to various embodiments, the optical film may have a refractive index having a full width at half maximum (FWHM) for a privacy function while maintaining brightness for a user convenience. According to an embodiment, as the first refractive index of the light blocking pattern layer130is increased with respect to the second refractive index of the prism structure170, the brightness and the full width at half maximum (FWHM) may be increased. According to an embodiment, as the first refractive index of the light blocking pattern layer130is increased within a certain range, the brightness may be the same, but the full width at half maximum (FWHM) is increased, and thus the privacy function may be reduced.

According to one embodiment, the ratio of the first refractive index to the second refractive index may be 0.9 to 1.1. For example, the first refractive index of the light blocking pattern layer130may be about 1.40 to about 1.65 and the second refractive index of the prism structure170may be about 1.49. According to an embodiment, the first refractive index of the light blocking pattern layer130may be about 1.04 of the second refractive index of the prism structure170.

FIG.10is a view for explaining an effect of an optical film according to a shape of a light absorption pattern of the present invention.

Referring toFIG.10, an optical film of the present invention (e.g., the optical film100ofFIG.1) may have a positive trapezoidal light absorption pattern (e.g., the light absorption pattern140ofFIG.3). For example, the area of the upper surface (e.g., the upper surface140aofFIG.3) of the light absorption pattern140may be smaller than the area of the lower surface (e.g., the lower surface140bofFIG.3). According to an embodiment, the brightness of the optical film of the present invention including the light absorption pattern140in the forward direction (e.g., the optical film100ofFIG.1) may be higher than the brightness of the optical film including the light absorption pattern in the reverse direction.

According to an embodiment, the viewing angle of the optical film of the present invention including the light absorption pattern140in a forward direction (e.g., the optical film100ofFIG.1) may be narrower than that of the optical film including the light absorption pattern in a reverse direction.

According to various embodiments of the present invention, an optical film (e.g., the optical film100ofFIG.1) may comprise a matte layer (e.g., the matte layer110ofFIG.1) including a plurality of protrusions (e.g., the protrusion111ofFIG.2), a first base film disposed under the matte layer (e.g., the first base film120ofFIG.1), a light blocking pattern layer (e.g., the light blocking pattern layer130ofFIG.1) disposed under the first base film and including a plurality of light absorption patterns (e.g., the light absorption pattern140ofFIG.1) arranged along a first direction (e.g., the Y-axis direction ofFIG.1), an adhesive layer (e.g., the adhesive layer150ofFIG.1) disposed under the light blocking pattern layer, and a second base film (e.g., the second base film ofFIG.1) attached to the light blocking pattern layer using the adhesive layer160and a prism structure (e.g., the prism structure170ofFIG.1) disposed under the second base film and including a plurality of prisms (e.g., the prisms171ofFIG.1) arranged along a second direction inclined at 80° to 100° with respect to the first direction.

According to various embodiments, the light blocking pattern layer includes a first surface (e.g., the first surface130aofFIG.3) facing the first base film and a second surface (e.g., the second surface130binFIG.3) opposite to the first surface and facing the adhesive layer, the light absorption pattern includes a upper surface (e.g., the upper surface140ainFIG.3) toward to the first surface, a lower surface (e.g., the lower surface140binFIG.3) disposed on the second surface and a side surface (e.g., the side surface140cinFIG.3) extending from the lower surface to the upper surface where the area of the upper surface may be smaller than the area of the lower surface.

According to various embodiments, the angle between the side surface and the lower surface may be 85° to 90°.

According to various embodiments, the upper surface may be spaced apart from the first surface.

According to various embodiments, a first pitch of the plurality of light absorption patterns (e.g., the first pitch (P1) ofFIG.3) may be 2 to 2.5 times of the second pitch of the plurality of prisms (e.g., the second pitch (P2) ofFIG.3).

According to various embodiments, a prism structure may be configured to condense light incident from the bottom of the prism structure and the light blocking pattern layer may be configured to condense light incident from the bottom of the light blocking pattern layer.

According to various embodiments, the plurality of light absorption patterns may be configured to reduce a viewing angle in the second direction and the plurality of prisms may be configured to reduce a viewing angle in the first direction.

According to various embodiments, each of the plurality of light absorption patterns may have a trapezoidal wedge shape.

According to various embodiments, the plurality of light absorption patterns may be arranged parallel to each other and spaced apart from each other.

According to various embodiments, the light blocking pattern layer may include a light transmitting area (e.g., the light transmitting area131ofFIG.3) positioned between the plurality of light absorption patterns.

According to various embodiments, the backlight unit may include an optical film, a light source (e.g., the light source210ofFIG.1) and a light guide plate (the light guide plate230ofFIG.1) configured to transmit at least a portion of light generated from the light source to the optical film.

According to various embodiments, a display device may include a liquid crystal display (LCD) panel and a backlight unit positioned under the LCD panel.

The optical film in the present invention as stated above, the backlight unit including the optical film, and the display device including the optical film and the backlight unit may not be limited to the foregoing embodiments and drawings. The person ordinary skilled in the art to which the present invention belongs will recognize that various substitutions, modifications, and changes are possible within the technical scope of the present invention.