Light guide plate of backlight unit and liquid crystal display device including the same

A display device includes: a display panel; a light source; and a light guide plate receiving light from the light source and providing the light to the display panel. The light guide plate includes an upper surface facing the display panel, a light incident surface facing the light source and a light opposing surface opposing the light incident surface. The upper surface includes a lens pattern and the lower surface incudes a prism pattern, the prism pattern includes a plurality of prisms arranged along a first direction from the light incident surface to the light opposing surface, each of the prisms has a length extending in a second direction along a length of the light incident surface, and among the prisms arranged along the first direction within the prism pattern, the lengths of the prisms increase as a distnace from the light incident surface increases.

This application claims priority to Korean Patent Application No. 10-2017-0005911, filed on Jan. 13, 2017, and all the benefits accruing therefrom under 35 U.S.C. § 119, the content of which in its entirety is herein incorporated by reference.

BACKGROUND

Exemplary embodiments of the invention relate to a display device having relative lightweight, thinness and high luminance.

2. Description of the Related Art

Liquid crystal display (“LCD”) devices are one of most widely used types of flat panel display (“FPD”) devices. An LCD device includes two substrates including electrodes therein and a liquid crystal layer interposed therebetween. Upon applying voltage to the two electrodes, liquid crystal molecules of the liquid crystal layer are rearranged such that an amount of transmitted light is controlled in the LCD device.

An LCD device, which is a passive light emitting device, includes a display panel which displays an image and a backlight unit for providing light to the display panel. The backlight unit is classified into a direct type backlight unit, an edge type backlight unit and a corner type backlight unit according to the position of the light source within the LCD device.

The edge type backlight unit is widely used because it is relatively easy to manufacture, light in weight and low in power consumption as compared to the direct type backlight unit. In the edge type backlight unit, a plurality of optical sheets for diffusing and collimating light provided from the light source may be disposed as a separate element between a light guide plate and the display panel.

SUMMARY

Exemplary embodiments of the invention are directed to a display device which has a reduced overall thickness by omitting an optical sheet separate from a light guide plate and substantially prevents degradation in image quality.

According to an exemplary embodiment, a display device includes: a display panel which displays an image with light; a light source which generates the light; and a light guide plate which receives the light from the light source and provides the light to the display panel. The light guide plate includes: an upper surface facing the display panel, the upper surface including a lens pattern, a lower surface opposing the upper surface, the lower surface including a prism pattern, a light incident surface facing the light source, and a light opposing surface opposing the light incident surface. The prism pattern includes a prism provided in plurality arranged along a first direction from the light incident surface to the light opposing surface, each of the prisms has a length extending in a second direction along a length of the light incident surface, and among the prisms arranged along the first direction within the prism pattern, the lengths of the prisms increase as a distance from the light incident surface increases.

The prism may be a recessed portion of the light guide plate or a protruded portion of the light guide plate.

The length of the prism may be in a range from about 3 μm (micrometers) to about 300 μm.

The prism may include an inclined surface extended from the lower surface of the light guide plate. The inclined surface of the prism may form an angle ranging from about 127 degrees to about 134 degrees with respect to the lower surface.

For prisms arranged adjacent to each other along the first direction, the inclined surfaces thereof may not be parallel to each other.

Each of the prisms may have a width extending in the first direction, and the width may range from about 3 μm to about 30 μm.

A pitch may be defined in the first direction between prisms arranged adjacent to each other along the first direction, and among the prisms arranged along the first direction within the prism pattern, the pitches of the prisms decrease as the distance from the light incident surface increases.

The prism pattern may be provided in plurality arranged along the second direction.

A pitch may be defined in the second direction between a first prism of a first prism pattern and a second prism of a second prism pattern arranged adjacent to each other along the second direction, and the pitch may be in a range from about 50 μm to about 300 μm.

The lens pattern may include a lens provided in plurality arranged along the second direction, each of the lenses having a semicircular or semi-elliptical cross-section and a length extending in the first direction.

The lens may have a width extending in the second direction, the width ranging from about 3 μm to about 30 μm.

The lens may have a height extending from the upper surface of the light guide plate, the height ranging from about 3 μm to about 15 μm.

The prism pattern may be provided in plurality along the second direction, and the light guide plate may further include a light scattering pattern provided in plurality between the prism patterns.

The light scatterning patterns may be arranged along the first direction, and among the light scattering patterns arranged along the first direction, a density of the light scattering patterns may be reduced as the distance from the light incident surface increases.

The light scattering pattern may have a discrete non-linear shape.

The light scattering pattern may have a discrete dot shape.

According to another exemplary embodiment, a display device includes: a display panel which displays an image with light; a light source which generates the light; and a light guide plate which receives the light from the light source and provides the light to the display panel. The light guide plate includes: an upper surface facing the display panel, the upper surface including a lens pattern, a lower surface opposing the upper surface, the lower surface including a prism pattern, a light incident surface facing the light source, and a light opposing surface opposing the light incident surface. A virtual line is defined extended in a first direction from the light incident surface to the light opposing surface, the virtual line perpendicular to a length of the light incident surface, the prism pattern includes a prism provided in plurality arranged along a center line extended in the first direction, the center line tilted by an angle ranging from about 0.5 degrees to about 10 degrees with respect to the virtual line, each of the prisms has a length extending in a second direction along the length of the light incident surface, and among the prisms arranged along the center line tilted with respect to the virtual line, the lengths of the prisms increase as a distance from the light incident surface increases.

According to another exemplary embodiment, a display device includes: a display panel which displays an image with light; a light source which generates the light; and a light guide plate which receives the light from the light source and provides the light to the display panel. The light guide plate includes: an upper surface facing the display panel, the upper surface comprsing a lens pattern, a lower surface opposing the upper surface, the lower surface incluidng a prism pattern, a light incident surface facing the light source, and a light opposing surface opposing the light incident surface. The prism pattern of the lower surface of the light guide plate includes a plurality of prisms arranged along a first direction from the light incident surface to the light opposing surface, each of the prisms has a length extending in a second direction along a length of the light incident surface, among the prisms arranged along the first direction within the prism pattern, the lengths of the prisms increase as a distance from the light incident surface increases, and with respect to a virtual line extended in the first direction to be perpendicular to the length of the light incident surface, the lens pattern of the upper surface of the light guide plate has a length forming a tilting angle ranging from about 0.5 degrees to about 10 degrees with respect to the virtual line.

DETAILED DESCRIPTION

Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings. Although the invention may be modified in various manners and have several exemplary embodiments, exemplary embodiments are illustrated in the accompanying drawings and will be mainly described in the specification. However, the scope of the invention is not limited to the exemplary embodiments and should be construed as including all the changes, equivalents and substitutions included in the spirit and scope of the invention.

In the drawings, thicknesses of a plurality of layers and areas are illustrated in an enlarged manner for clarity and ease of description thereof. When a layer, area, or plate is referred to as being related to another elements such as being “on” another layer, area, or plate, it may be directly on the other layer, area, or plate, or intervening layers, areas, or plates may be present therebetween. Conversely, when a layer, area, or plate is referred to as being related to another element such as being “directly on” another layer, area, or plate, intervening layers, areas, or plates are absent therebetween. Further when a layer, area, or plate is referred to as being related to another element such as being “below” another layer, area, or plate, it may be directly below the other layer, area, or plate, or intervening layers, areas, or plates may be present therebetween. Conversely, when a layer, area, or plate is referred to as being related to another element such as being “directly below” another layer, area, or plate, intervening layers, areas, or plates are absent therebetween.

Throughout the specification, when an element is referred to as being “connected” to another element, the element is “mechanically or physically” to the other element, or “electrically connected” to the other element with one or more intervening elements interposed therebetween.

Some of the parts which are not associated with the description may not be provided in order to specifically describe exemplary embodiments of the invention and like reference numerals refer to like elements throughout the specification.

A conventional display device including a plurality of optical sheets between a light guide plate and a display panel to control a direction of light provided to the display panel, has an increased overall thickness owing to the plurality of optical sheets disposed as separate elements from the light guide plate and the display panel. Therefore, there exists an increasing tendency to omit the plurality of optical sheets between the light guide plate and the display panel, thereby forming a slimmer display device.

Although a display device is described as being an LCD device in exemplary embodiments, exemplary embodiments are not limited thereto, and a display device in which a display panel that receives light from a backlight unit to display an image may be included in the scope of the invention.

FIG. 1is an exploded perspective view illustrating an exemplary embodiment of a display device according to the invention.

Referring toFIG. 1, the display device according to an exemplary embodiment includes an upper frame110, a display panel120, an intermediate frame130, a light source unit140, a light guide plate150, a reflection sheet160and a lower frame170.

Hereinafter, the intermediate frame130, the light source unit140, the light guide plate150, the reflection sheet160and the lower frame170are collectively referred to as a backlight unit.

The upper frame110has an opening window defined therein for exposing an active area of the display panel120to outside the display device and is disposed so as to cover a front edge and a side surface of the display panel120. The upper frame110may include a relatively rigid metal material such as stainless steel or a material having relatively good heat dissipation properties such as aluminum or an aluminum alloy.

The display panel120may be provided in a quadrangular plate shape and receive an electric signal from outside thereof to display an image. The display panel120may include a first (display) substrate121, a second (display) substrate123opposing the first substrate121, an optical control layer such as a liquid crystal layer (not illustrated) between the first substrate121and the second substrate123, or the like.

The first substrate121includes a plurality of pixel electrodes arranged in a matrix, a switching element such as a thin film transistor applying a driving voltage to each of the pixel electrodes, and various signal lines for driving the pixel electrodes and the thin film transistor.

The second substrate123is disposed to oppose the first substrate121. The second substrate123includes a common electrode including a transparent conductive material and a color filter. The color filter may include red, green and blue color filters.

The liquid crystal layer (not illustrated) is interposed between the first substrate121and the second substrate123. An orientation of molecules of the liquid crystal layer is rearranged by an electric field formed between the pixel electrode and the common electrode. As such, the rearranged liquid crystal layer adjusts or controls the transmittance of light emitted from the backlight unit, and the adjusted light passes through the color filter to display an image to outside the display panel120.

In addition, a lower polarizer (not illustrated) may be disposed on a rear surface of the first substrate121and an upper polarizer (not illustrated) may be disposed on an upper surface of the second substrate123. The upper polarizer and the lower polarizer may have a total planar area corresponding to that of the display panel120.

The upper polarizer may transmit only a specific polarized light among light arriving from the outside the display panel and absorb or block the remaining light. The lower polarizer plate may transmit only a specific polarized light among the light output from the backlight unit, and absorb or block the remaining light.

A driving circuit board125may be disposed on at least one side of the display panel120. The driving circuit board125may generate and/or apply various control signals or a power signal for driving the display panel120.

The display panel120and the driving circuit board125may be electrically connected to each other by at least one flexible printed circuit board (“FPCB”)127. The FPCB127may be a chip on film (“COF”) or a tape carrier package (“TCP”). The number of the FPCBs127may have various values depending on the size and driving scheme of the display panel120.

A driving chip129may be mounted on the FPCB127. The driving chip129may generate various driving signals for driving the display panel120. The driving chip129may be represented by a driver integrated circuit (“IC”) or a source IC in which a timing controller and/or a data driving circuit are integrated into one chip.

The intermediate frame130may support a rear edge of the display panel120and may accommodate the light source unit140, the light guide plate150, the reflection sheet160, or the like.

The intermediate frame130may have a polygonal frame shape in which a hollow space is defined. In an exemplary embodiment, for example, the intermediate frame130may have a quadrangular frame shape in which an empty space is defined. The intermediate frame130may be formed as a single, unitary member or may be formed from a plurality of separately provided pieces as required and then assembled. The intermediate frame130may include a flexible material such as plastic, or may be formed as an injection molded member such as through an injection molding process or the like.

The light source unit140includes a light source141and a light source substrate143on which the light source141is disposed.

The light source141may be disposed at an edge or one side surface of the light guide plate150. That is, the light source141may generate and emit light to the edge or one side surface of the light guide plate150. The light source141may include at least one light emitting diode (“LED”) chip (not illustrated) and a package (not illustrated) for accommodating the LED chip. In an exemplary embodiment, for example, the LED chip (not illustrated) may be a gallium nitride (GaN)-based LED chip emitting a blue light.

The number of the light sources141may have various values in consideration of the size of the display panel120, luminance uniformity, or the like. The light source substrate143may be a printed circuit board (“PCB”) or a metal printed circuit board (“metal PCB”).

The light source unit140may be disposed or formed on one side surface, opposite side surfaces or all four side surfaces of the light guide plate150in consideration of the size and luminance uniformity of the display panel120. That is, the light source unit140may be disposed or formed on at least one of edge portions of the light guide plate150. Herein, the light source unit140is assumed to be disposed on one side surface of the light guide plate150.

Although not illustrated inFIG. 1, a wavelength conversion unit (not illustrated) may be disposed between the light source unit140and the light incident surface of the light guide plate150. The wavelength conversion unit (not illustrated) may include a material for converting the wavelength of light emitted from the light source unit140. In an exemplary embodiment, for example, the wavelength conversion unit may convert the wavelength of a blue light emitted from a blue LED light source into a white light.

Although described as a plate, such as having a relatively large cross-sectional thickness for ease of description, for convenience of explanation, the light guide plate150may be formed in the form of a sheet or a film for slimming down the display device. The light guide plate150may be provided in a sheet or film shape for which the cross-sectional thickness is smaller than that of the plate and is relatively small as compared to the planar size thereof, That is, the light guide plate150may include both a plate and a film for guiding light.

Hereinafter, one surface of the light guide plate150facing the display panel120is referred to as an upper surface150a,another surface of the light guide plate150opposing the upper surface150ais referred to as a lower surface150b,another surface of the light guide plate150facing the light guide plate140is referred to as a light incident surface150c,and another surface of the light guide plate150opposing the light incident surface150cis referred to as a light opposing surface150d.Side surfaces of the light guide plate150connect the upper surface150aand the lower surface150bto each other, and the light incident surface150cmay be one of the side surfaces. Light is emitted from the light guide plate150through the upper surface150aand light is incident into the light guide plate150through the light incident surface150c.

For convenience of explanation, a direction perpendicular to the light incident surface150cis referred to as a first direction D1, a direction along which a length of the light incident surface150cextends is referred to as a second direction D2, and a thickness direction of the light guide plate150is referred to as a third direction D3. The display device and components thereof are disposed in a plane defined by the first and second directions D1and D2, while a thickness of the display device and components thereof are taken in the third direction D3.

The light guide plate150according to an exemplary embodiment may include a body portion151and a lens pattern152disposed or formed on the body portion151.

The body portion151may include a material having a light transmitting property, such as an acrylic resin, e.g., polymethylmethacrylate (“PMMA”), polycarbonate, and a tempered glass, so as to efficiently guide the light. The body portion151may define portions of side surfaces and/or the lower surface150bof the light guide plate150.

The lens pattern152disposed or formed on the body portion151may include a hard coating exclusive resin, and the resin may be ultraviolet (“UV”)-cured to have properties similar to polycarbonate. The resin may include an oligomer, a monomer, a photoinitiator, silicone, or the like, and may be classified into a soft resin and a hard resin depending on the content of the silicone and monomer.

The details of the shape of the plurality of lenses within the lens pattern152disposed or formed on the body portion151will be described below.

The reflection sheet160may include, for example, polyethylene terephthalate (“PET”) and be reflective, and one surface of the reflection sheet160may be coated with a diffusion layer including, for example, titanium dioxide. In addition, the reflection sheet160may include a material including a metal such as silver (Ag).

The lower frame170may include a metal material having relatively good rigidity and heat dissipation characteristics. In an exemplary embodiment, for example, the lower frame170may include at least one selected from stainless steel, aluminum, an aluminum alloy, magnesium, a magnesium alloy, copper, a copper alloy and an electrogalvanized steel sheet.

FIG. 2is a perspective view illustrating the light guide plate and the light source unit according to an exemplary embodiment, andFIG. 3is an enlarged perspective view illustrating area “A” ofFIG. 2.FIGS. 2 and 3are perspective views illustrating the upper surface150aof the light guide plate150and the light incident surface150cof the light guide plate150according to an exemplary embodiment.

Referring toFIGS. 2 and 3, the light guide plate150according to an exemplary embodiment may include the lens pattern152extended from an upper surface of the body portion151such as to define the upper surface150aof the light guide plate150. Each of the lenses of the lens pattern152may be lengthwise elongated in the first direction D1, and the lenses are arranged along the second direction D2. InFIG. 3, numeral152is used to indicate a single lens for convenience of explanation, but numeral152may be considered as indicating the collection of lenses. Each lens may have a semicircular or semi-elliptical cross-section, but exemplary embodiments are not limited thereto. In an exemplary embodiment, for example, each lens may have a circular or triangular cross-section and the cross-sectional areas of the plurality of lenses may be different from each other. Alternatively, the lens pattern152may include a plurality of lenses elongated in the second direction D2and arranged in the first direction D1. The lenses of the lens pattern152extend from a common surface of the body portion151, such as from the upper surface thereof. Portions of the upper surface of the body portion151which are between the lenses are coplanar with each other.

A thickness t of the body portion151according to an exemplary embodiment may be in a range from about 0.5 millimeter (mm) to about 3.5 millimeters (mm). As an example, when including PMMA or PC, the body portion151may have a thickness t in a range from about 2.0 mm to about 3.5 mm. As another example, when including a tempered glass, the body portion151may have a thickness tin a range from about 0.5 mm to about 1.5 mm.

The lens according to an exemplary embodiment may have a width W1ranging from about 3 micrometers (μm) to about 30 μm in the second direction D2and a height H1ranging from about 3 μm to about 15 μm in the third direction D3.FIGS. 2 and 3illustrate that lenses disposed adjacent to each other in the second direction D2are continuously formed, that is, having no space therebetween. However, exemplary embodiments are not limited thereto, and the plurality of lenses may be disposed or formed at a predetermined distance from each other in the second direction D2.

The light guide plate150according to an exemplary embodiment includes the lens pattern152as the upper surface150aof the light guide plate150so that light emitted from the light guide plate150may be collimated and the light guide plate150may not be visible from the outside.

FIG. 4is an enlarged perspective view illustrating a modified exemplary embodiment of a light guide plate150relative to a light source unit140according to the invention. For example,FIG. 4is a perspective view illustrating an upper surface150aand a light incident surface150cof the light guide plate150according to an alternative exemplary embodiment. For convenience of explanation, repeated description of the light guide plate150described above will be omitted from the description related to the light guide plate150ofFIG. 4.

Referring toFIG. 4, the light guide plate150according to an alternative exemplary embodiment may include a lens pattern152including a plurality of lenses disposed or formed on the body portion151so as to define the upper surface150aof the light guide plate150. In a top plan view of the plane defined by the first and second directions D1and D2, the lenses of the lens pattern152may each extend with a tilting angle θ1ranging from about 0.5 degrees to about 10 degrees with respect to a virtual line VL parallel to a first direction D1.

As such, the light guide plate150according to an alternative exemplary embodiment is configured such that the plurality of lenses forming the collective lens pattern152as the upper surface150aof the light guide plate150are inclined at a predetermined tilting angle θ1with respect to the virtual line VL parallel to the first direction D1, and accordingly, a moiré stain may be substantially prevented from appearing.

FIG. 5is a perspective view illustrating another exemplary embodiment of a light guide plate and a light source unit according to the invention,FIG. 6is an enlarged perspective view illustrating area “B” ofFIG. 5,FIG. 7is an enlarged perspective view illustrating area “C” ofFIG. 6, andFIG. 8is a cross-sectional view taken along line I-I′ ofFIG. 7.FIGS. 5 and 6are perspective views illustrating the lower surface150band the light incident surface150cof the light guide plate150according to an exemplary embodiment.

Referring toFIGS. 5 and 6, the light guide plate150according to an exemplary embodiment may include a prism pattern153disposed or formed at the lower surface150bof the light guide plate150. The prism pattern153may include a plurality of prisms as a material or layer separate from that of the body portion151, but the invention is not limited to. In an alternative embodiment, the prisms of the prism pattern153may be defined by portions of the body portion151.

The prism pattern153may include a plurality of prisms, including prism153a,prism153band prisms therebetween, arranged along the first direction D1perpendicular to the light incident surface150c.A single one prism may be arranged along the first direction D1. Each prism among the prism153a,the prism153band prisms therebetween may have a length which extends in the second direction D2parallel to the light incident surface150c.The prisms are discrete shapes disposed spaced apart from each other.

The lengths of the plurality of prisms arranged along the first direction D1may increase gradually as a distance from the light incident surface150cincrease. That is, a length11of a (first) prism153aadjacent to (e.g., closest to) the light incident surface150cis the smallest and a length12of a (last) prism153bdisposed adjacent to (e.g., closest to) the light opposing surface150dis the largest.

Each of the prisms of the prism pattern153may have a length ranging from about 3 μm to about 300 μm. Lengths of the prisms within a prism pattern153increase as a distance of the prisms from the light incident surface150cincreases.

The prisms of the prism pattern153according to an exemplary embodiment may be formed in at least one of an engraved (e.g., recessed) form and an embossed (e.g., protruded) form, relative to a common surface of the body portion151of the light guide plate150. InFIGS. 5 through 8, the prisms of the prism pattern153according to an exemplary embodiment are assumed to be engraved (e.g., recessed) patterns, extended into the body portion151of the light guide plate150from a lowermost surface150bof the overall light guide plate150. That is, it is considered that the body portion151extends to include a portion (or layer) of the light guide plate150in which the prisms are recessed. Inclined surfaces of the prisms and the lower surface of the body portion151may together form the lower surface150bof the overall light guide plate150. Portions of the lower surface150bwhich are between the prisms are coplanar with each other.

The prism pattern153as a group of prisms arranged in the first direction D1, may be provided in plurality along a second direction D2parallel to the light incident surface150c.A pitch P1between the plurality of prism patterns153disposed adjacently along the second direction D2may be in a range of about 50 μm to about 300 μm. The pitch P1is taken between same positions among the prisms within a group of prisms arranged in the first direction D1defining the prism pattern153, such as being between virtual lines taken commonly at the center of each prism, but not being limited thereto.

Referring toFIGS. 7 and 8, prisms153cand153dare disposed between the first and last prisms153aand153b.Each of the prisms153athrough153bwithin a prism pattern153have a width W2in a range from about 3 μm to about 30 μm in the first direction D1. In addition, the each of the prisms153athrough153bmay be spaced apart from each other by a predetermined pitch P2in the first direction D1. The pitch P2is taken between same positions among the prisms within a group of prisms arranged in the first direction D1defining the prism pattern153, such as being between edges of the prisms closest to the light incident surface150c.

FIGS. 7 and 8illustrate that the pitch P2between the prisms153cand153ddisposed adjacent to each other in the first direction D1is substantially the same, but exemplary embodiments are not limited thereto. In an alternative exemplary embodiment, the pitch P2between the prisms153cand153ddisposed adjacent to each other in the first direction D1may decrease from the light incident surface150ctoward the light opposing surface150d,as a distance from the light incident surface150cincreases.

Each of the prisms within a group of prisms arranged in the first direction D1defining the prism pattern153, includes inclined surfaces extending from the lower surface150bof the light guide plate150. InFIG. 8, for example, an angle θ2between inclined surfaces153c′ and153d′ of the prisms153cand153d,and the lower surface150bof the light guide plate150, respectively, may be in a range from about 127 degrees to about 134 degrees. The inclined surfaces153c′ and153d′ of the prisms such as153cand153dmay be parallel to each other along an entirety of the length of such prisms, but are not limited thereto.

As such, referring toFIGS. 5 and 6once again, the light guide plate150according to an exemplary embodiment includes, at the lower surface150bthereof, the plurality of prisms within a single prism pattern153that increase gradually in length as prisms are position along the first direction from the light incident surface150ctoward the light opposing surface150d,so that light emitted through the light guide plate150may be uniformly provided to the display panel. In an exemplary embodiment, for example, the light provided from the light source unit140becomes weaker from the light incident surface150ctoward the light opposing surface150d,such that lengths of the plurality of prisms within a single prism pattern153increase gradually from the light incident surface150ctoward the light opposing surface150d.

Accordingly, in order to provide light uniformly to the display panel120, among pairs of prisms within a single prism pattern153(e.g.,153aand153bor153cand153dillustrated inFIGS. 5-8), an amount of light reflected at the prism closer to the light incident surface150cis reduced and an amount of light reflected at the prism closer to the light opposing surface150dis increased.

That is, according to an exemplary embodiment, the length of the prism153adisposed closest to the light incident surface150cis substantially minimized and the lengths of remaining prisms within the single prism pattern153gradually increase to the prism153b,so that uniform light may be provided to the display panel120.

FIG. 9is an enlarged perspective view illustrating a modified exemplary embodiment of a light guide plate150according to the invention, andFIG. 10is a cross-sectional view taken along line II-II′ ofFIG. 9.FIGS. 9 and 10are perspective views illustrating a portion of a lower surface150bof the light guide plate150according to an alternative exemplary embodiment. For convenience of explanation, repeated description of the light guide plate150inFIGS. 5 through 8will be omitted from the description related to the light guide plate150ofFIGS. 9 and 10.

Referring toFIGS. 9 and 10, the light guide plate150according to an alternative exemplary embodiment may include a prism pattern153disposed or formed at the lower surface150b.The prism pattern153according to an alternative exemplary embodiment may be disposed or formed in at least one of an engraved (e.g., recessed) form and an embossed (e.g., protruded) form. For purpose of explanation, the prisms of the prism pattern153according to an alternative exemplary embodiment is assumed to be a protruded pattern extended away from a main portion of the body portion151of the light guide plate150from a lower surface of the body portion151which is common to each prism. That is, it is considered that a portion of the body portion151extends to define the protruded prisms of the prism pattern153. Inclined surfaces of the prisms and the portions of the body portion151therebeteween may together form the lower surface150bof the overall light guide plate150. Portions of the lower surface of the body portion151which are between the prisms are coplanar with each other.

Among prisms within the prism pattern153, prisms153eand153fare arranged along a first direction D1perpendicular to a light incident surface (not illustrated). The prisms153eand153fmay have lengths13and14which extend in a second direction D2parallel to the light incident surface150c. The prisms153eand153fmay represent a pair of prisms within a single prism pattern153, such as being between a first prism closest to the light incident surface150cand a second prism closest to the light opposing surface150d.

The lengths of the plurality of prisms arranged along the first direction D1may increase gradually from the light incident surface150ctoward the light opposing surface150d.Referring toFIG. 9, the lengths13and14of the plurality of prisms153eand153farranged along the first direction D1may increase gradually toward the first direction D1. That is, lengths of the prisms represented by prisms153eand153fwithin a prism pattern153increase as a distance of the prisms from the light incident surface150cincreases. Each of the prisms within a prism pattern153, such as represented by prisms153eand153f,may have a length in a range from about 3 μm to about 300 μm.

As representing the prisms within a prism pattern153, each of the prisms153eand153fmay have a width W2in a range from about 3 μm to about 30 μm in the first direction D1.

In addition, as further representing the prisms within a prism pattern153, the prisms153eand153fmay be spaced apart from each other by a predetermined pitch P2in the first direction D1.

Each of the prisms within a group of prisms arranged in the first direction D1defining the prism pattern153, includes inclined surfaces extending from the lower surface150bof the body portion151of the light guide plate150. As further representing the prisms within a prism pattern153, an angle θ2between inclined surfaces153e′ and153fof the prisms153eand153fand the lower surface150bof the body portion151of the light guide plate150may be in a range from about 127 degrees to about 134 degrees. The inclined surfaces153e′ and153f′ of the prisms such as153eand153fmay be parallel to each other along an entirety of the length of such prisms, but are not limited thereto.

As such, the light guide plate150according to an exemplary embodiment includes, as the lower surface150bof the light guide plate150, the plurality of prisms153eand153fextended from a lower surface of the body portion151, that increase gradually in length from the light incident surface150ctoward the light opposing surface150dso that light emitted through the light guide plate150may be uniformly provided to the display panel120.

FIG. 11is an enlarged perspective view illustrating a modified exemplary embodiment of a portion of a light guide plate according to the invention.FIG. 11is a perspective view illustrating a lower surface150band a light incident surface150cof the light guide plate150according to an alternative exemplary embodiment. For convenience of explanation, repeated description of the light guide plate150according to previous exemplary embodiments will be omitted from the description related to the light guide plate150ofFIG. 11.

Referring toFIG. 11, the light guide plate150according to an alternative exemplary embodiment may include a prism pattern153disposed or formed at the lower surface150b.The prism pattern153may include a plurality of prisms arranged along a common center line CL tilted by an angle θ3ranging from about 0.5 degrees to about 10 degrees with respect to a virtual line VL parallel to a first direction D1. The prisms of a prism pattern153may be aligned along the center line CL. Each prism within a single prism pattern153may by symmetrical with respect to the center line CL. Each prism within a prism pattern153may have a center thereof defined along the second direction, and the center line CL extends through the center of each prism. Among prisms in the single prism pattern153, lengths of the prisms may increase gradually as a distance from the light incident surface150cincreases toward the first direction D1. In addition, the prism pattern153may be provided in plurality along a second direction D2.

As such, the light guide plate150according to an alternative exemplary embodiment is configured such that an arrangement line of the prisms within the prism pattern153disposed or formed at the lower surface150bhas a predetermined tilting angle θ3with respect to the virtual line VL parallel to the first direction D1, and accordingly, moiré stains may be substantially prevented from appearing.

FIG. 12is an enlarged perspective view illustrating another modified exemplary embodiment of a portion of a light guide plate150according to the invention, andFIG. 13is an enlarged perspective view illustrating still another modified exemplary embodiment of a light guide plate150according to the invention.FIGS. 12 and 13are perspective views illustrating a lower surface150band a light incident surface150cof the light guide plate150according to an alternative exemplary embodiment. For convenience of explanation, repeated description of the light guide plate150according to previous exemplary embodiments will be omitted from the description related to the light guide plate150inFIGS. 12 and 13.

Referring toFIGS. 12 and 13, the light guide plate150according to an alternative exemplary embodiment may include a prism pattern153disposed or formed at the lower surface150b.The prism pattern153may include a plurality of prisms arranged along a first direction D1, and lengths of the prisms may increase gradually as a distance from the light incident surface150cincrease toward the first direction D1. In addition, the prism pattern153may be provided in plurality along a second direction D2.

The light guide plate150according to an alternative exemplary embodiment may further include a light scattering pattern154between the prism patterns153. The light scattering pattern154may be disposed between the prisms within a prism pattern153.

The light scattering pattern154may be provided in plural to have a discrete shape such as a hairline (e.g., non-linear line) shape (seeFIG. 12) or a dot shape (seeFIG. 13). The light scattering patterns154are discrete shapes disposed spaced apart from each other. The light scattering patterns154scatter light passing through the inside of the light guide plate150to allow the light to be emitted through an upper surface150aof the light guide plate150.

The light scattering patterns154are disposed or formed at the lower surface150bof the light guide plate150so that a certain portion of the light guide plate150does not appears as a bright portion or a dark portion because at the light scattering patterns154, light may be condensed at or may not reach the certain portion may be canceled out. That is, the light scattering patterns154may control the occurrence of the light or dark portion generated because of the interference of light due to a light path difference.

A quantity of the light scattering pattern154in a unit area (e.g., density) may be gradually reduced as a distance from the light incident surface150ctoward the light opposing surface150dincrease. As the light guide plate150includes the prism pattern153at the lower surface150b,where lengths of the prisms of the prism pattern153increase from the light incident surface150ctoward the light opposing surface150d,an area of the light guide plate150adjacent to the light incident surface150cmay appear as a relatively dark portion. Accordingly, the light scattering pattern154is formed at a region adjacent to the light incident surface150c,to have a greater density, so that light may be uniformly emitted from an entire surface of the light guide plate150.

In an exemplary embodiment of manufacturing a light guide plate150, such a light scattering pattern154may be formed by processing a surface using a sand blaster or by applying a paint that scatters light. That is, the light scattering pattern154may be recessed from the lower surface150bof the light guide plate150or may be protruded from the lower surface of the body portion151.

FIG. 14is an enlarged perspective view illustrating yet another modified embodiment of a portion of a light guide plate150according to the invention.FIG. 14is a perspective view illustrating a lower surface150bof the light guide plate150according to an alternative exemplary embodiment. For convenience of explanation, repeated description of the light guide plate150according to previous exemplary embodiments will be omitted from the description related to the light guide plate150inFIG. 14.

Referring toFIG. 14, the light guide plate150according to an alternative exemplary embodiment may include a prism pattern153disposed or formed at the lower surface150b.The prism pattern153may include a plurality of prisms, such as153gand153h,arranged along a first direction D1. Among prisms within a single prism pattern153, lengths of the prisms in a second direction D2may increase gradually as a distance of the prisms from the light incident surface150cincreases in the first direction D1.

Inclined surfaces153g′ and153h′ of the prisms153gand153hdisposed adjacent to each other in the first direction D1may be formed to be not parallel to each other or to the second direction D2. That is, each of the prisms153gand153hmay have irregularly shaped inclined surfaces153g′ and153h′. That is, the inclined surfaces153g′ and153h′ of the prisms such as153gand153hmay not be parallel to each other along an entirety of the length of such prisms, but are not limited thereto.

As such, the light guide plate150according to an alternative exemplary embodiment includes the plurality of prisms such as153gand153hincluding the irregularly shaped inclined surfaces153g′ and153h′, and accordingly, moiré stains may be substantially prevented from appearing.

As set forth hereinabove, according to one or more exemplary embodiment, an overall thickness of a display device may be reduced by omitting the optical sheet of a conventional display device, and the manufacturing costs may be reduced.

According to one or more exemplary embodiments, the display device may collimate the light emitted from the light source and substantially prevent the light guide plate from being visible, by the light guide plate including the lens pattern on the upper (light emission) surface of the light guide plate.

According to one or more exemplary embodiments, the light guide plate of the display device includes the prism pattern on the lower surface of the light guide plate so that light emitted from the light guide plate may be uniformly provided to the display panel.

According to one or more exemplary embodiments, the display device may substantially prevent moiré stains from appearing by the light guide plate including discrete patterns disposed or formed at the upper and lower surfaces of the light guide plate tilted or having no regularity.