Display device with a window including a light-path changing layer

A display device includes: a display panel to display an image; a window covering the display panel, and including a display area through which the image is to be transmitted, and a non-display area surrounding the display area, the window including: a window base opposite the display panel; a printing layer below the window base; and a light-path changing layer between the window base and the printing layer, the light-path changing layer including: an optical structure; and a resin coating the optical structure; and an adhesive layer between the display panel and the window.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and all the benefits accruing under 35 U.S.C. § 119 of Korean Patent Application No. 10-2015-0090907, filed on Jun. 26, 2015, with the Korean Intellectual Property Office (KIPO), the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

One or more aspects of example embodiments of the present invention relate to a display device.

2. Description of the Related Art

Electronic devices that provide images to users, such as televisions (“TV”), digital cameras, laptop computers, navigation devices, and mobile phones, include a display device for displaying the images. A display device includes a display panel for generating an image to display the image, and a window on top of the display panel to protect the display panel.

The image generated on the display panel may be transmitted through the window to be viewed by a user. The window includes a display area on which an image is displayed, and a non-display area around (e.g., surrounding) the display area. The non-display area of the window may be designed in various colors by using a printing layer. However, light reaching the printing layer may be scattered by reflection (e.g., total reflection), thus causing light leakage.

The above information disclosed in this Background section is for enhancement of understanding of the background of the present invention, and therefore, it may contain information that does not constitute prior art.

SUMMARY

One or more aspects of example embodiments of the present invention are directed to a display device capable of reducing or preventing light leakage caused by reflection (e.g., total reflection).

According to an exemplary embodiment of the present invention, a display device includes: a display panel configured to display an image; a window covering the display panel and including a display area through which the image is to be transmitted, and a non-display area surrounding the display area, the window including: a window base opposite the display panel; a printing layer below the window base; and a light-path changing layer between the window base and the printing layer, the light-path changing layer including: an optical structure; and a resin coating the optical structure; and an adhesive layer between the display panel and the window.

The optical structure may have a refractive index that is less than that of the resin by 0.01 or more.

The optical structure may include at least one selected from SiO2, polymethylmethacrylate (“PMMA”), tetrafluoroethylene (“TFE”), a fluorinated ethylene propylene copolymer (“FEP”), a hollow glass bead, and an aerogel.

The optical structure may include one of a bead shape, a lens shape, a prism shape, a trapezoid shape, and an elliptical shape.

The display device may further include a base film between the window base and the printing layer.

The light-path changing layer may be between the base film and the printing layer.

The light-path changing layer may include a base film.

The optical structure may correspond to a pattern layer on the base film.

The display device may further include a pattern layer corresponding to the optical structure on a surface of the base film, the pattern layer having a low refractive index, and the base film having a high refractive index.

The display device may further include: a pattern layer on another surface of the base film, the pattern layer having a low refractive index; and an optically clear adhesive (“OCA”) layer on the pattern layer, the OCA layer having a high refractive index.

The pattern layer may have one of a lens shape and a prism shape.

The display device may further include an optically clear adhesive (“OCA”) layer between the window base and the printing layer.

The light-path changing layer may include the OCA layer.

The optical structure may be located in the OCA layer.

The display device may further include a light-absorbing member at a side of the window.

The printing layer may be at the non-display area and may contact the adhesive layer.

The printing layer may include a first decor printing layer, a second decor printing layer, and a light-shielding printing layer.

The first decor printing layer may include a pearlescent pigment and may have a transparent color.

The second decor printing layer may be a white printing layer.

The light-shielding printing layer may be a black printing layer and may contact the adhesive layer.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of a display device according to one or more embodiments of the present invention are described as an organic light emitting diode (“OLED”) display device, for convenience. However, the display device is not limited thereto, and aspects and features of the present invention may be applied to a liquid crystal display (“LCD”) device, a plasma display panel (“PDP”) device, a field emission display (“FED”) device, and/or the like.

In addition, in the accompanying drawings, the display device according to one or more exemplary embodiments of the present invention is illustrated as an active matrix organic light emitting diode (“AMOLED”) display device having a 2Tr-1 Cap (e.g., two transistors-one capacitor) structure in which a single pixel includes two thin film transistors (“TFT”) and a single capacitor. However, the present invention is not limited thereto. Thus, in the OLED display device according to one or more exemplary embodiments, the number of TFTs, the number of capacitors, and the number of wirings are not limited. As used herein, the term “pixel” refers to a minimum unit for displaying an image, and the OLED display device displays an image through a plurality of pixels.

Hereinafter, a display device100according to an exemplary embodiment of the present invention will be described with reference toFIGS. 1, 2, and 3.

FIG. 1is an exploded perspective view illustrating the display device100according to an exemplary embodiment of the present invention.

Referring toFIG. 1, the display device100includes a display panel200including a pixel area PX and a non-pixel area NPX, a housing610configured to accommodate (e.g., receive or house) the display panel200, an impact-absorbing sheet620between the display panel200and the housing610, a window300including a display area DA and a non-display area NDA, and an adhesive layer500between the display panel200and the window300. The window300is on top of (e.g., above or covering) the display panel200.

The non-pixel area NPX may surround the pixel area PX, and the non-display area NDA may surround the display area DA. The pixel area PX of the display panel200corresponds to the display area DA of the window300, and the non-pixel area NPX of the display panel200corresponds to the non-display area NDA of the window300. For ease of illustration, the housing610, the display panel200, the window300, and the adhesive layer500are illustrated as being separated from one another inFIG. 1.

The pixel area PX of the display panel200may be an area at which an image is generated to be displayed. The non-pixel area NPX of the display panel200may be an area at which an image is not generated. The image generated on the display panel200is transmitted through the window300to be viewed by a user.

The display panel200is not limited to a particular type (or kind) of display panel. For example, the display panel200may include a self-emission-type display panel, such as an OLED display panel, or a non-self-emission-type display panel, such as an LCD panel and/or an electrophoretic display (“EPD”) panel. A detailed description of the display panel200will be provided later below with reference toFIG. 10.

The housing610is configured to accommodate (e.g., receive or house) the display panel200.FIG. 1illustrates the housing610as a single unitary member that provides a space for accommodating (e.g., receiving or housing) the display panel200by way of example. However, in another exemplary embodiment, the housing610may have a structure in which two or more members are coupled to each other to form the housing610.

The housing610may further accommodate (e.g., receive or house) a circuit board on which a driving element is mounted, in addition to the display panel200, and as necessary, may further accommodate a power supply, such as a battery.

The impact-absorbing sheet620is located between the display panel200and the housing610, and is configured to absorb an impact that may be applied to the display panel200. Accordingly, the impact-absorbing sheet620may prevent or substantially prevent an external impact from being applied directly to the display panel200. However, the present invention is not limited thereto, and in some embodiments, the impact-absorbing sheet620may be omitted.

The window300is arranged at a side of the display panel200on which an image is displayed. The window300is coupled to the housing610to form an exterior of the display device100, along with the housing610.

A polarizer400may be on the display panel200. For example, the polarizer400may be between the display panel200and the adhesive layer500. The polarizer400may convert an optical axis of light irradiated from the display panel200.

The polarizer400may be arranged on the display panel200so as to cover at least a portion of the display panel200. In another exemplary embodiment, the polarizer400may be formed to have the same or substantially the same size as that of the display panel200, so as to cover an entire surface or substantially the entire surface of the display panel200. The polarizer400may have a monolayer structure, or a multilayer structure including a polarizing film and a phase difference film.

In addition, in some embodiments, the display device100may further include a touch screen panel. The touch screen panel may be arranged on the display panel200. For example, the touch screen panel may be arranged between the display panel200and the polarizer400, or may be on the polarizer400. Based on an input signal provided from the touch screen panel, the display panel200may provide an image to a user that corresponds to the input signal.

Hereinafter, the window300will be described in greater detail with reference toFIGS. 2 and 3.

FIG. 2is a perspective view illustrating the window300ofFIG. 1.FIG. 3is a cross-sectional view illustrating the display device according to an exemplary embodiment of the present invention. InFIG. 3, the housing610and the impact-absorbing sheet620are omitted.

The window300is arranged above (e.g., on top of) the display panel200to protect the display panel200from external scratches.

An upper surface of the window300includes the display area DA, and the non-display area NDA surrounding the display area DA. The display area DA may include an area on which an image to be provided to an observer is displayed. The non-display area DA may include an area at which an image is not displayed. The non-display area NDA may be printed in black. However, the color of the non-display area NDA is not limited thereto, and the non-display area NDA may be printed in various suitable colors other than black. For example, the non-display area NDA may be printed in white.

The window300may include a window base310, a base film330, an optically clear adhesive (“OCA”) layer320between the window base310and the base film330, a printing layer340, and a light-path changing layer350between the base film330and the printing layer340.

The window base310is arranged opposite to the display panel200. A planar area of the window base310includes a display area DA and a non-display area NDA surrounding the display area DA, in a manner corresponding to a planar area of the window300including the display area DA and the non-display area NDA.

The window base310may be formed of a light-transmissive transparent film. Accordingly, an image generated at the pixel area PX of the display panel200may be transmitted through the window base310at the display area DA to be provided to a user.

In addition, the window base310may include (or be formed of) plastic or glass that has impact resistance. The window base310may have a quadrangular planar shape with rounded corners. In an exemplary embodiment, the window base310illustrated inFIG. 2has a shape in which an edge (e.g., a right edge)311is curved. However, the shape of the window base310is not limited thereto. For example, in some exemplary embodiments, the window base310may have various suitable shapes, such as a circular shape including curved corners, and/or one or more curved edges (e.g., a curved left edge).

Although not illustrated, a hard coating layer and/or a protection layer may be arranged on the window base310. In this case, the hard coating layer may use any suitable coating composition capable of enhancing the surface hardness of the window base310. For example, an ultraviolet (“UV”)-curable coating composition that does not require a high temperature treatment may be used.

The hard coating layer may include (or be formed of) an acrylate-based monomer or an inorganic compound. The hard coating layer may enhance the surface hardness and/or chemical resistance of the window base310.

The protection layer may be arranged on the hard coating layer. The protection layer may include a functional coating layer, such as, for example, an anti-finger (“AF”) coating layer, an anti-reflection (“AR”) coating layer, and/or an anti-glare (“AG”) coating layer.

The printing layer340is on a portion of a lower surface of the window base310adjacent to the display panel200, in the non-display area NDA. In other words, the non-display area NDA corresponds to an area at which the printing layer340is located, and the display area DA corresponds to an area at which the printing layer340is absent (e.g., not located).

Referring toFIG. 3, the base film330may be below the window base310. The OCA layer320may be between (e.g., interposed between) the window base310and the base film330.

The base film330may include a transparent film, such as polyethylene terephthalate (“PET”). However, the base film330may include any suitable light-transmissive transparent film, without being limited to the type (e.g., kind) thereof.

The base film330may include the printing layer340on a surface thereof, and the light-path changing layer350may be located between the base film330and the printing layer340.

Hereinafter, the light-path changing layer350will be described in greater detail with reference toFIG. 4.

FIG. 4is a cross-sectional view illustrating the printing layer340and the light-path changing layer350of the display device according to an exemplary embodiment of the present invention.

The light-path changing layer350is arranged between the window base310and the printing layer340to change a path of light. In more detail, the light-path changing layer350changes a path of reflected (e.g., totally reflected) light, which may cause light leakage, to thereby prevent or substantially prevent the reflected (e.g., totally reflected) light from reaching the printing layer340.

The light-path changing layer350changes a path of light based on Fresnel reflection. As used herein, the term “Fresnel reflection” refers to reflection occurring when light passes through an interface between materials having different refractive-indices. Accordingly, the light-path changing layer350may have various suitable configurations that may adjust a path of light based on Fresnel reflection.

The light-path changing layer350may include an optical structure351having a low refractive index mixed with a resin353having a high refractive index, so as to be printed on the base film330. However, the light-path changing layer350is not limited thereto. For example, in another exemplary embodiment, the light-path changing layer350may include a pattern of an optical structure formed on a surface of the base film330, and a resin having a low refractive index formed (e.g., printed or coated) thereon, and/or may be formed in a manner in which an optical structure is inserted into the base film330and/or the OCA layer320.

Although the optical structure351is illustrated as having a bead shape inFIG. 4, the shape of the optical structure351is not limited thereto, and in some embodiments, the optical structure351may have a lens shape, a prism shape, a trapezoid shape, and/or an elliptical shape. The optical structure351may include (or be formed of) at least one selected from SiO2, poly(methyl methacrylate) (“PMMA”), tetrafluoroethylene (“TFE”), fluorinated ethylene propylene copolymer (“FEP”), a hollow glass bead, and aerogel.

Referring toFIG. 4, the light-path changing layer350may include the optical structure351having a low refractive index nlow, and the resin353having a high refractive index nhigh. The optical structure351may have a refractive index in a range of about 1.3 to about 1.6, and the resin353that coats the optical structure351may have a refractive index in a range of about 1.6 to about 3.0. More particularly, the optical structure351may have a refractive index less than that of the resin353by about 0.01 or more.

As described in the foregoing, a path of light is changed between the optical structure351and the resin353having different refractive indices based on Fresnel reflection. In other words, the light-path changing layer350changes a path of light to prevent or substantially prevent reflected (e.g., totally reflected) light, which may cause light leakage, from reaching the printing layer340.

According to some exemplary embodiments, a light-absorbing member380may be further included as illustrated inFIG. 3.

The light-absorbing member380may be arranged at a side surface of the window300, and may absorb the light having the path changed by the light-path changing layer350to extinguish the light. In this case, light that is not absorbed by the light-absorbing member380may again undergo reflection (e.g., total reflection) to be absorbed by the polarizer400. Accordingly, the light-absorbing member380may reduce (e.g., significantly reduce) light leakage.

As illustrated inFIG. 3, the light-absorbing member380may be arranged at side surfaces of the window base310, the OCA layer320, and the base film330, respectively. However, the location of the light-absorbing member380is not limited thereto. For example, in another exemplary embodiment, the light-absorbing member380may extend onto side surfaces of the light-path changing layer350and/or the printing layer340, respectively, or may be omitted.

The base resin is a material that may be combined with the light-absorbing material and/or the UV-curing accelerator to form a base for the light-absorbing member380. While the base resin may be formed of an acrylate-based polymer, the material used for forming the base resin is not limited thereto. The base resin formed of an acrylate-based polymer may be formed by irradiating UV light on a composition including an acrylate monomer, an acrylate oligomer, and/or a photo-initiator, to thereby perform a reaction among the composition.

The light-absorbing material is a material for preventing or reducing light leakage. In other words, the light-absorbing material may be a material for performing a primary function of the light-absorbing member380. The light-absorbing material includes colored particles. The colored particles may include black particles, such as carbon black. However, the color of the colored particles is not limited thereto, and in some embodiments, the colored particles may include particles having various suitable colors that may provide a light-absorbing effect. Since carbon black used as the colored particles absorbs light in a visible light range, an excellent light leakage prevention or reduction effect may be achieved through the use of carbon black as the light-absorbing material.

The UV-curing accelerator includes a material for allowing the UV-curing of the base resin to be performed relatively easily. As the light-absorbing member380may include the UV-curing accelerator, the curing process of the base resin may be performed relatively easily, even though the light-absorbing member380may include the black particles.

A description of the changed path of the reflected (e.g., totally reflected) light and the light leakage reduction effect due to the light-path changing layer350and the light-absorbing member380included in the display device according to one or more exemplary embodiments will be further provided below with reference toFIGS. 5 to 8.

The printing layer340may be on a portion of a surface of the base film330at the non-display area NDA. The printing layer340may prevent or substantially prevent the outward visibility of a driver for driving the display panel200and/or an accommodating portion in which the display panel200is accommodated (e.g., received).

The printing layer340may include (or be formed of) an organic material having a color (e.g., a predetermined color). Accordingly, the color of the printing layer340at the non-display area NDA of the window base310may be displayed to a user.

The printing layer340may include various suitable colors, for example, black or white. In the case that the printing layer340is black, the printing layer340may include a black matrix. In the case that the printing layer340is white, the printing layer340may include an organic insulating material, such as a white resin. In another exemplary embodiment, the printing layer340may include (or be formed of) an opaque inorganic insulating material, such as CrOx or MoOx, or an opaque organic insulating material, such as a black resin. Accordingly, the printing layer340may block light in the display panel200, prevent or substantially prevent the visibility of an internal structure of the display panel200, and determine the color of the window300.

The printing layer340may be formed on the base film330by printing a printing composition on the base film330, and the base film330may be bonded to the window base310. However, the manner of forming the printing layer340on the base film330, and the manner of which the base film330is bonded to a surface of the window base310are not limited thereto, and may include various suitable manners known in the pertinent art.

The printing layer340may have a monolayer structure. However, the structure of the printing layer340is not limited thereto, and the printing layer340may have a multilayer structure including a plurality of layers having the same or substantially the same thickness, or different thicknesses.

Referring toFIG. 3, the printing layer340includes a plurality of printing layers341,342, and343. The printing layers341,342, and343include a first decor printing layer341, a second decor printing layer342, and a light-shielding printing layer343arranged on a portion of a surface of the base film330at the non-display area NDA.

The first decor printing layer341may have a transparent color, and may include a pearlescent pigment having a glittering characteristic. In other words, the first decor printing layer341may provide a glittering effect that is visible to a user. In another exemplary embodiment, the first decor printing layer341may include a pigment representing various textures.

The second decor printing layer342may be a white printing layer. However, the color of the second decor printing layer342is not limited thereto, and the second decor printing layer342may have a different color other than white, or may have one or more of various different colors. While the second decor printing layer342is illustrated as a single layer in an exemplary embodiment, the second decor printing layer342may include a plurality of layers having the same color, or different colors, so as to provide a relatively distinct color.

The light-shielding printing layer343may be a black printing layer. The black light-shielding printing layer343may have a light shielding ratio higher than those of the first decor printing layer341and the second decor printing layer342.

While the three printing layers including the first decor printing layer341, the second decor printing layer342, and the light-shielding printing layer343are illustrated inFIG. 3by way of example, the number of printing layers is not limited thereto. In another exemplary embodiment, more than three printing layers may be arranged on a portion of a surface of the base film330at the non-display area NDA.

In some embodiments, the printing layer340may contact the adhesive layer500between the display panel200and the window300. For example, the printing layer340may contact the adhesive layer500in case that the window base310may have a circular shape including curved corners.

The adhesive layer500is located between the polarizer400and the window300, and may couple the display panel200to the window300.

To prevent or substantially prevent the adhesive layer500from reducing the luminance of light emitted from the display panel200, the adhesive layer500may have a transparent characteristic. The adhesive layer500may include (or be formed of) a transparent polymer resin that has an adhesive property and may be photocurable or thermocurable. For example, the adhesive layer500may include (or be formed of) a photocurable resin that may be cured by light irradiation.

Hereinafter, the light leakage reduction effect according to an exemplary embodiment will be described in greater detail with reference toFIGS. 5 to 8.

FIG. 5is a cross-sectional view illustrating a path of reflected (e.g., totally reflected) light in a display device without a light-path changing layer.FIG. 6is an enlarged view of the area “B” illustrated inFIG. 5.FIG. 7is a cross-sectional view illustrating a path of reflected (e.g., totally reflected) light in the display device according to an exemplary embodiment of the present invention.FIG. 8is an enlarged view of the area “C” illustrated inFIG. 7.

The housing610and the impact-absorbing sheet620are omitted inFIGS. 5 and 7.FIG. 6illustrates a printing layer34including a first decor printing layer34-1including a single layer, a second decor printing layer34-2including four layers having the same or substantially the same thickness, and a light-shielding printing layer34-3including two layers having the same or substantially the same thickness by way of example.FIG. 8illustrates the printing layer340including the first decor printing layer341including a single layer, the second decor printing layer342including four layers having the same or substantially the same thickness, and the light-shielding printing layer343including two layers having the same or substantially the same thickness, by way of example. However, the structures of the printing layers34and340are not limited thereto, and the printing layers34and340may have a monolayer structure or a multilayer structure including a plurality of layers having different thicknesses.

A window30of the display device illustrated inFIGS. 5 and 6includes a window base31and the printing layer34below the window base31. In more detail, the window base31, an OCA layer32, a base film33, and the printing layer34are sequentially arranged.

Referring toFIG. 5, light generated by an OLED21and reflected (e.g., totally reflected) at a surface of the window base31corresponding to an outermost optical interface may be divided into three lights. For example, the three lights may include a light a having a great incident angle θ and absorbed by a polarizer40, a light b that is split at various layers based on Fresnel reflection to reach the printing layer34, and a light c having a small incident angle θ′, for example, in a range of about 5 degrees (°) to about 10°, and reaching the printing layer34subsequent to undergoing a reflection (e.g., a first total reflection) once.

Among the three lights a, b, and c, the light c causes light leakage that may be observed in the display device. The reflected (e.g., totally reflected) light c that is generated by the OLED21, and that reaches a surface of the window base31, is reflected by the window base31to reach the printing layer34. The light c that has reached the printing layer34is dispersed and dissipated at the printing layer34, and may be observed as light leakage L at the non-display area NDA of the window30.

In comparison, the window300of the display device according to an exemplary embodiment illustrated inFIGS. 7 and 8includes the window base310, the OCA layer320, the base film330, the printing layer340, the light-path changing layer350between the base film330and the printing layer340, and the light-absorbing member380at a side surface of the window300.

Thus, the display device according to an exemplary embodiment further includes the light-path changing layer350and the light-absorbing member380, when compared to the display device illustrated inFIGS. 5 and 6.

The light-path changing layer350located between the window base310and the printing layer340may change a path of the light. The light-absorbing member380arranged at a side surface of the window300may absorb the light having the path changed by the light-path changing layer350to extinguish the light.

Referring toFIG. 8, the light-path changing layer350may include the optical structure351having a low refractive index, and the resin353having a high refractive index. A path of light between the optical structure351and the resin353having different refractive indices is changed based on Fresnel reflection. In other words, the light-path changing layer350changes the path of light to prevent or substantially prevent the reflected (e.g., totally reflected) light, which may cause light leakage, from reaching the printing layer340.

Referring toFIG. 7, the light-path changing layer350changes a path of a reflected (e.g., a totally reflected) light c′, which is generated by an OLED210and reflected from a surface of the window base310, to prevent or substantially prevent the light c′ from reaching the printing layer340. The light c′, which has the changed path, is absorbed by the light-absorbing member380and is extinguished. Accordingly, light leakage at the non-display area NDA of the window300is reduced or prevented.

Further, a light d that is not absorbed by the light-absorbing member380may again undergo reflection (e.g., total reflection) and may be absorbed by the polarizer400. Accordingly, the light-absorbing member380may significantly reduce light leakage.

As described in the foregoing, the display device according to an exemplary embodiment of the present invention further includes the light-path changing layer350and the light-absorbing member380, and thus, the reflected (e.g., totally reflected) light, which may cause light leakage, may not reach the printing layer340. Accordingly, the display device according to an exemplary embodiment of the present invention may reduce or prevent light leakage.

Hereinafter, a pixel of the display panel200(refer toFIG. 1) will be described with reference toFIGS. 9 and 10.

FIG. 9is a schematic plan view illustrating a pixel of the display panel200at the area “A” ofFIG. 1.FIG. 10is a cross-sectional view taken along the line I-I′ ofFIG. 9.

Referring toFIGS. 9 and 10, the OLED display device100according to an exemplary embodiment is illustrated as an AMOLED display device having a 2Tr-1 Cap (e.g., 2 transistors-1 capacitor) structure. Each pixel in the display area DA (refer toFIG. 1) includes two TFTs, for example, a switching TFT10and a driving TFT20, and a capacitor, for example, a capacitor80.

However, the present invention is not limited thereto, and in some embodiments, each pixel may include any suitable number of transistors and capacitors. Accordingly, the OLED display device100may have various structures, for example, a structure in which three or more TFTs and two or more capacitors are included in a pixel, and additional wirings may be further included. As used herein, the term “pixel” refers to a minimum unit for displaying an image, and the display area may display an image using a plurality of pixels.

The OLED display device100includes a first substrate101. The switching TFT10, the driving TFT20, the capacitor80, and the OLED210are respectively formed in the plurality of pixels on the first substrate101. Gate lines151extending in a direction, and data lines171and common power lines172crossing and insulated from the gate line151are further formed on the first substrate101.

The pixels may be located at crossing regions of the gate lines151, the data lines171, and the common power lines172. However, the location of the pixels is not limited thereto.

The OLED210may include a first electrode211, an organic light emitting layer212on the first electrode211, and a second electrode213on the organic light emitting layer212. The first electrode211may be a positive electrode (e.g., an anode electrode), for example, a hole injection electrode. The second electrode213may be a negative electrode (e.g., a cathode electrode), for example, an electron injection electrode. However, the types (kinds) of the first and second electrodes211and213are not limited thereto, and the first electrode211may be a cathode electrode and the second electrode213may be an anode electrode based on a driving scheme of the OLED display device100.

Holes and electrons injected into the organic light emitting layer212are combined with each other to form excitons. The OLED210emits light by energy generated when the excitons fall from an excited state to a ground state.

The capacitor80includes a pair of storage electrodes. For example, the capacitor80may include first and second storage electrodes158and178, with an insulating layer160therebetween. The insulating layer160may be a dielectric material. Capacitance of the capacitor80may be determined by an amount of electric charge stored in the capacitor80, and the level of a voltage across the first and second storage electrodes158and178.

The switching TFT10includes a switching semiconductor layer131, a switching gate electrode152, a switching source electrode173, and a switching drain electrode174. The driving TFT20includes a driving semiconductor layer132, a driving gate electrode155, a driving source electrode176, and a driving drain electrode177.

The switching TFT10may be used as a switching element for selecting a pixel to emit light. The switching gate electrode152is connected to the gate line151. The switching source electrode173is connected to the data line171. The switching drain electrode174is spaced from the switching source electrode173, and is connected to the first storage electrode158.

The driving TFT20applies, to the first electrode211, a driving power for emitting the organic light emitting layer212of the OLED210for the corresponding pixel selected by the switching TFT10. The driving gate electrode155is connected to the first storage electrode158which is connected to the switching drain electrode174. The driving source electrode176and the second storage electrode178are connected to the common power line172. The driving drain electrode177is connected to the first electrode211of the OLED210through a drain contact hole181.

The switching TFT10is operated by a gate voltage applied to the gate line151to transmit a data voltage applied to the data line171to the driving TFT20.

A voltage having a level equal to or substantially equal to a difference between a level of a common voltage applied from the common power line172to the driving TFT20and a level of the data voltage transmitted from the switching TFT10is stored in the capacitor80. A current having a level corresponding to the level of the voltage stored in the capacitor80flows to the OLED210through the driving TFT20, to enable the OLED210to emit light.

Hereinafter, the configuration of the OLED display device100according to an exemplary embodiment of the present invention will be described in greater detail with reference toFIGS. 9 and 10.

In the present exemplary embodiment, the first substrate101may include an insulating substrate formed of glass, quartz, ceramic, plastic, or the like. However, the material used for forming the first substrate101is not limited thereto, and the first substrate101may include a metallic substrate formed of stainless steel, or the like.

A buffer layer120is on the first substrate101. The buffer layer120prevents or substantially prevents the infiltration of impure elements into the first substrate101, and planarizes a surface of the first substrate101. However, the buffer layer120is not necessarily required, and thus, may be omitted based on the type (kind) of the first substrate101, process conditions, and/or the like.

The driving semiconductor layer132is on the buffer layer120. The driving semiconductor layer132may include a channel region135that is not doped with impurities, and a source region136and a drain region137formed at respective sides of the channel region135and doped with impurities (e.g., p-type impurities).

A gate insulating layer140is on the driving semiconductor layer132. The driving gate electrode155, the gate line151(refer toFIG. 9), and the first storage electrode158are formed on the gate insulating layer140. The driving gate electrode155overlaps at least a portion of the driving semiconductor layer132, for example, the channel region135. The driving gate electrode155prevents or substantially prevents impurities from being doped in the channel region135, when the impurities are doped in the source region136and the drain region137of the driving semiconductor layer132during the formation of the driving semiconductor layer132.

The insulating layer160is on the gate insulating layer140, and covers the driving gate electrode155. The insulating layer160may include an insulating interlayer. The gate insulating layer140and the insulating layer160include contact holes through which the source region136and the drain region137of the driving semiconductor layer132are respectively exposed.

The driving source electrode176, the driving drain electrode177, the data line171, the common power line172, and the second storage electrode178are on the insulating layer160at the display area DA. The driving source electrode176and the driving drain electrode177are connected to the source region136and the drain region137of the driving semiconductor layer132through the contact holes, respectively.

A passivation layer180is formed on the insulating layer160to cover the driving source electrode176, the driving drain electrode177, and the like. The passivation layer180may include (or be formed of) an organic material, such as polyacrylate, polyimide, and/or the like. The passivation layer180may be a planarization layer.

The drain contact hole181is formed in the passivation layer180, and the driving drain electrode177is exposed through the drain contact hole181. The first electrode211is on the passivation layer180, and is connected to the driving drain electrode177through the drain contact hole181of the passivation layer180.

A pixel defining layer190is on the passivation layer180to cover a portion of the first electrode211. An aperture199is formed in the pixel defining layer190, and the first electrode211is exposed through the aperture199. In other words, the first electrode211corresponds to the aperture199of the pixel defining layer190.

The organic light emitting layer212is on the first electrode211within the aperture199of the pixel defining layer190, and the second electrode213is on the pixel defining layer190and the organic light emitting layer212.

One of the first electrode211and the second electrode213may include (or be formed of) a transparent conductive material, and the other thereof may include (or be formed of) a transflective conductive material or a reflective conductive material. The OLED display device100may be one of a top-emission-type display device, a bottom-emission-type display device, or a both-side (e.g., dual) emission-type display device, based on the type of materials used for forming the first and second electrodes211and213.

The organic light emitting layer212may have a multilayer structure including one or more of a light emitting layer, a hole injection layer (“HIL”), a hole transporting layer (“HTL”), an electron transporting layer (“ETL”), and/or an electron injection layer (“EIL”).

A capping layer230may be further included on the second electrode213. The capping layer230may protect the OLED210, and may help the light generated from the organic light emitting layer212to be efficiently emitted externally.

The OLED display device100according to an exemplary embodiment of the present invention may further include a thin film encapsulation layer250on the capping layer230.

The thin film encapsulation layer250may include one or more of inorganic layers251,253, and255, and one or more of organic layers252and254. The thin film encapsulation layer250may have a structure in which the inorganic layers251,253, and255, and the organic layers252and254are alternately stacked. The inorganic layer251may be a lowermost layer. In other words, the inorganic layer251may be closest to the OLED210from among the inorganic layers251,253, and255, and the organic layers252and254. However, the present invention is not limited thereto, and in some embodiments, an organic layer may be the lowermost layer (e.g., may be closest to the OLED210from among the inorganic layers and the organic layers. Further, while the thin film encapsulation layer250inFIG. 10is illustrated as including the three inorganic layers251,253, and255, and the two organic layers252and254, the present invention is not limited thereto.

The thin film encapsulation layer250may have a thickness that is less than or equal to about 10 micrometers (μm). Accordingly, the OLED display device100may have a relatively thin overall thickness.

In the case where the thin film encapsulation layer250is arranged on the OLED210, an additional substrate may not be provided on the thin film encapsulation layer250(e.g., may be omitted). In this case, a flexible characteristic of the display panel200may be enhanced.

FIG. 11is a cross-sectional view illustrating a display device according to another exemplary embodiment of the present invention.

The display device according to another exemplary embodiment has the same or substantially the same configuration as that of the display device ofFIG. 3, except for a structure of the light-path changing layer and a structure of the base film. Accordingly, a configuration of the display device according to the embodiment ofFIG. 11that is different from that of the display device ofFIG. 3will be described in more detail herein, and the same or substantially the same configuration therebetween is illustrated using the same reference numeral.

Referring toFIG. 11, a light-path changing layer350′ according to an exemplary embodiment of the present invention includes a base film330′, and a pattern layer354on a surface of the base film330′ and having a low refractive index.

A pattern352is formed on a lower surface of the base film330′, and a resin having a low refractive index is on (e.g., printed on) the pattern352to form the pattern layer354having a low refractive index. The base film330′ has a high refractive index, and the pattern352may be a three-dimensional (“3D”) pattern having one of a lens shape and a prism shape.

As compared to the light-path changing layer350of the display device ofFIG. 3, it may be appreciated that the pattern layer354having a low refractive index corresponds to the optical structure351(refer toFIG. 4), and the base film330′ having a high refractive index corresponds to the resin353(refer toFIG. 4) coating the optical structure351. In other words, the pattern layer354may have a refractive index that is less than that of the base film330′ by about 0.01 or more.

Accordingly, the light-path changing layer350′ according to an exemplary embodiment of the present invention may change a path of light based on Fresnel reflection due to a difference between refractive indices of the pattern layer354and the base film330′, to thereby reduce light leakage.

However, the present invention is not limited thereto, and in another exemplary embodiment, the pattern layer354may be on an upper surface of the base film330. In this case, an OCA layer having a high refractive index may be on the pattern layer354, and a path of light may be changed based on Fresnel reflection due to a difference between refractive indices of the pattern layer354and the OCA layer, to thereby reduce light leakage.

FIG. 12is a schematic cross-sectional view illustrating a display device according to another exemplary embodiment of the present invention.

The display device according to the exemplary embodiment ofFIG. 12has the same or substantially the same configuration as that of the display device ofFIG. 3, except for a structure of a light-path changing layer and a structure of a OCA layer. Accordingly, the same or substantially the same configuration therebetween is illustrated using the same reference numeral, and repeated description thereof will be omitted.

Referring toFIG. 12, a light-path changing layer350″ according to an exemplary embodiment of the present invention includes an optical structure351and an OCA layer320′ that coats the optical structure351.

FIG. 12illustrates the optical structure351as having a bead shape by way of example. However, in another exemplary embodiment, the optical structure351may have one of a lens shape, a prism shape, a trapezoid shape, and/or an elliptical shape. The OCA layer320′ has a high refractive index, and the optical structure351may have a refractive index that is less than that of the OCA layer320′ by about 0.01 or more.

The light-path changing layer350″ according to the exemplary embodiment ofFIG. 12may change a path of light between the optical structure351and the OCA layer320having different refractive indices based on Fresnel reflection. The light-path changing layer350″ may prevent or substantially prevent the light having the changed path from reaching the printing layer340, to thereby reduce light leakage.

Hereinafter, the light leakage reduction effect of the display device according to an exemplary embodiment of the present invention will be described in greater detail with reference toFIGS. 13 and 14.

As illustrated in the foregoing with reference toFIG. 3, the light-path changing layer350of the display device according to an exemplary embodiment of the present invention includes the optical structure351having a low refractive index, and the resin353coating the optical structure351and having a high refractive index.

FIG. 13is a view illustrating a simulation result of a light path of the display device according to an exemplary embodiment of the present invention. The simulation is performed in the light-path changing layer350including a bead, for example, the optical structure351, having a refractive index of 1.40 and a diameter of 2 μm, and the resin353having a refractive index of 1.57.

It may be verified fromFIG. 13that a path of light incident on the light-path changing layer350is changed due to a difference between refractive indices of the bead, that is, the optical structure351, and the resin353. Accordingly, it may be appreciated that the light-path changing layer350changes the path of the light to prevent or substantially prevent the light from reaching the printing layer340, thereby reducing light leakage.

FIG. 14illustrates graphs comparing amounts of light leakage being reduced based on a refractive index of the bead, that is, the optical structure351(refer toFIG. 13), of the display device according to an exemplary embodiment. The simulations are performed on a display device without the light-path changing layer (LPCL) and on display devices including the light-path changing layer350(refer toFIG. 13) that includes beads (e.g., the optical structure351) having respective refractive indices of 1.45, 1.40, 1.35, and 1.30.

When a light leakage ratio of the display device without the LPCL is set to be about 100%, and the respective refractive indices of the beads included in the light-path changing layer350are 1.45, 1.40, 1.35, and 1.30, it may be verified from the graphs ofFIG. 14that the beads have respective light leakage ratios of 70.0%, 60.6%, 56.7%, and 54.2%. In other words, when the respective refractive indices of the beads are 1.45, 1.40, 1.35, and 1.30, the respective light leakage ratios of the beads are increased by 30.0%, 39.4%, 43.4% and 45.8%, as compared to the light leakage ratio of the display device without the LPCL.

In this regard, it may be verified based on the simulation results that the light leakage ratio (%) is reduced up to 45.8% in the display device according to an exemplary embodiment of the present invention as compared to that of the display device without the LPCL.

Hereinafter, a light leakage reduction effect of the display device according to another exemplary embodiment will be described in greater detail with reference toFIGS. 15 and 16.

As illustrated in the foregoing with reference toFIG. 11, the light-path changing layer350′ of the display device according to an exemplary embodiment of the present invention includes the pattern layer354on a surface of the base film330′ and having a low refractive index.

The base film330′ has a high refractive index, and the pattern352may be a 3D pattern having one of a lens shape and a prism shape.

FIG. 15is a view illustrating a simulation result of a light path of the display device according to another exemplary embodiment of the present invention. The light-path changing layer350′ of the display device according to an exemplary embodiment includes the base film330′ having a refractive index of 1.57, and the pattern layer354having a refractive index of 1.40 and having the prism pattern352that has a width of about 4 μm and an apical angle of about 90° on a lower surface of the base film330′.

It may be verified fromFIG. 15that a path of light incident on the light-path changing layer350′ is changed due to a difference between refractive indices of the pattern layer354and the base film330′. Accordingly, it may be appreciated that the light-path changing layer350′ changes the path of light to prevent or substantially prevent the light from reaching the printing layer340, thereby reducing light leakage.

FIG. 16illustrates graphs comparing amounts of light leakage being reduced based on a refractive index of the prism pattern352(refer toFIG. 11) of the display device according to another exemplary embodiment of the present invention. The simulations are performed on a display device without the light-path changing layer (LPCL), and on the display devices including the light-path changing layer350′ (refer toFIG. 11) that includes the prism patterns352(also referred to as “prisms” inFIG. 16) having respective refractive indices of 1.45, 1.40, 1.35, and 1.30.

When a light leakage ratio of the display device without the LPCL is set to be about 100%, and the respective refractive indices of the prisms included in the light-path changing layer350′ are 1.45, 1.40, 1.35, and 1.30, it may be verified from the graphs ofFIG. 16that the prisms have respective light leakage ratios of 72.2%, 67.9%, 59.46%, and 53.6%. In other words, when the respective refractive indices of the prisms are 1.45, 1.40, 1.35, and 1.30, the respective light leakage ratios of the prisms are increased by 27.8%, 32.1%, 40.6% and 46.4%, as compared to the light leakage ratio of the display device without the LPCL.

In this regard, it may be verified based on the simulation results that the light leakage ratio (%) is reduced up to 46.4% in the display device according to an exemplary embodiment of the present invention as compared to that of the display device without the LPCL.

As set forth above, according to one or more exemplary embodiments of the present invention, the light-path changing layer is provided at the window to reduce light that reaches the printing layer due to reflection (e.g., total reflection).

Accordingly, the display device according to one or more exemplary embodiments of the present invention may reduce light leakage.

From the foregoing, it will be appreciated that various embodiments of the present invention have been described herein for purposes of illustration, and that various modifications may be made without departing from the spirit and scope of the present invention. It will be appreciated that various features of the above described embodiments may be mixed and matched in any suitable manner, unless specifically described to the contrary, to produce further embodiments consistent with the spirit and scope of the present invention. Accordingly, the various embodiments disclosed herein are not intended to be limiting of the spirit and scope of the present invention, as defined by the following claims, and their equivalents.