Patent Publication Number: US-11665922-B2

Title: Display device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This U.S. non-provisional patent application is a continuation of U.S. patent application Ser. No. 16/239,141 filed on Jan. 3, 2019, which claims priority under 35 U.S.C. § 119 to Korean Patent Application Nos. 10-2018-0001424 and 10-2018-0039477, filed on Jan. 4, 2018 and Apr. 5, 2018, respectively, the disclosures of which are incorporated by reference herein in their entireties. 
    
    
     TECHNICAL FIELD 
     The present inventive concept relates to a display device, and in particular, to a display device with high reliability. 
     DISCUSSION OF RELATED ART 
     Various display devices are being developed. For example, various display devices are being developed for use in multimedia devices such as televisions, mobile phones, navigation systems, computer monitors, gaming machines, and the like. Various components are assembled to fabricate a display device. The display device is generally designed so that it can function reliably. 
     SUMMARY 
     According to an exemplary embodiment of the inventive concept, a display device may include a substrate element including a base layer, a circuit layer provided on the base layer, and a device layer electrically connected to the circuit layer, wherein the device layer is configured to generate light, and the base layer forms a plane defined by a first direction and a second direction perpendicular to each other. The display device further includes an encapsulation element provided on the substrate element to seal the device layer, a sealing element provided along edge regions of the encapsulation element to connect the encapsulation and substrate elements to each other, an optical element provided on the encapsulation element, a window element provided on the substrate element, an adhesive element provided between the optical element and the window element to connect the optical element to the window element, and a filling element provided between the window and substrate elements, wherein the filling element is spaced apart from the optical and adhesive elements, and is overlapped with the sealing element when viewed in a direction normal to the plane. 
     In an exemplary embodiment of the inventive concept, the sealing element may include an inner side surface defining a hermetically-sealed internal space, along with the substrate element and the encapsulation element, and an outer side surface facing the inner side surface, and a portion of the outer side surface may be in contact with the filling element. 
     In an exemplary embodiment of the inventive concept, a bottom surface of the filling element may be in contact with a portion of a top surface of the encapsulation element, a side surface of the encapsulation element adjacent to the filling element, a portion of a bottom surface of the encapsulation element adjacent to the side surface of the encapsulation element, the outer side surface of the sealing element, and a portion of a top surface of the substrate element. 
     In an exemplary embodiment of the inventive concept, when measured in the second direction, a width of the filling element may be larger than a width of the sealing element, and the filling element may cover the sealing element, when viewed in the direction normal to the plane. 
     In an exemplary embodiment of the inventive concept, the display device may further include a driver chip mounted on the substrate element. The substrate element may include a first region, which is not covered by the encapsulation element, and a second region, which is adjacent to the first region and is covered with the encapsulation element. The driver chip may be provided on the first region, and at least a portion of the filling element may be overlapped with the driver chip in the second direction. 
     In an exemplary embodiment of the inventive concept, the filling element may include a first filling element, which is overlapped with the driver chip when viewed in the direction normal to the plane, and a second filling element, which is spaced apart from the first filling element and is not overlapped with the driver chip. 
     In an exemplary embodiment of the inventive concept, when measured in the second direction, a width of the first filling element may be less than a width of the second filling element. 
     In an exemplary embodiment of the inventive concept, a plurality of the first elements may be provided, and when measured in the first direction, a distance between each of the first filling elements may be larger than a distance between the second filling element and one of the first filling elements adjacent to the second filling element. 
     In an exemplary embodiment of the inventive concept, the filling element may include a first filling element, which is overlapped with the driver chip, and a second filling element, which is spaced apart from the first filling element and is not overlapped with the driver chip. The first filling element may be spaced apart from the driver chip, when viewed in the direction normal to the plane. 
     In an exemplary embodiment of the inventive concept, the display device may further include a touch unit provided between the encapsulation element and the optical element, and a touch flexible circuit board electrically connected to the touch unit. 
     In an exemplary embodiment of the inventive concept, a plurality of the filling elements may be provided. The filling elements may include a first filling element and a second filling element, which are arranged in the first direction with the touch flexible circuit board interposed therebetween when viewed in the direction normal to the plane, and the first filling element and the second filling element may be spaced apart from the touch flexible circuit board. 
     In an exemplary embodiment of the inventive concept, the sealing element may include a frit. 
     In an exemplary embodiment of the inventive concept, the circuit layer may include a thin-film transistor including a semiconductor pattern, a control electrode spaced apart from the semiconductor pattern, and input and output electrodes which are respectively coupled to two portions of the semiconductor pattern. The device layer may include an organic light emitting diode including a first electrode coupled to the thin-film transistor, a second electrode provided on the first electrode, and a luminescent layer provided between the first and second electrodes. 
     According to an exemplary embodiment of the inventive concept, a display device may include a substrate element including a base layer, a circuit layer provided on the base layer, and a device layer electrically connected to the circuit layer, wherein the device layer is configured to generate light, the base layer forms a plane defined by a first direction and a second direction perpendicular to each other, and the substrate element includes a first region and a second region adjacent to the first region in the second direction. The display device further includes an encapsulation element provided to cover the second region and to expose the first region, the encapsulation element including a third region and a fourth region adjacent to the third region in the second direction, a sealing element provided along edge regions of the encapsulation element to connect the encapsulation element to the substrate element, an optical element provided to cover the fourth region and to expose the third region, a window element provided on the substrate element, an adhesive element provided between the optical element and the window element to connect the optical element to the window element, and a plurality of filling elements provided between the window element and the base layer. The filling elements may be spaced apart from the optical element and the adhesive element and may be overlapped with a portion of each of the first region and the third region. 
     In an exemplary embodiment of the inventive concept, the sealing element may include an inner side surface defining a hermetically-sealed internal space, along with the substrate element and the encapsulation element, and an outer side surface facing the inner side surface, and the outer side surface may be in contact with at least one of the filling elements. 
     In an exemplary embodiment of the inventive concept, a bottom surface of at least one of the filling elements may be in contact with a portion of a top surface of the encapsulation element, a side surface of the encapsulation element adjacent to the filling element, a portion of a bottom surface of the encapsulation element adjacent to the side surface of the encapsulation element, the outer side surface of the sealing element, and a portion of a top surface of the substrate element. 
     In an exemplary embodiment of the inventive concept, the display device may further include a driver chip that is provided on the first region and is overlapped with at least one of the filling elements, when viewed in a direction normal to the plane. When measured in the second direction, a width of one of the filling elements overlapped with the driver chip may be less than a width of another of the filling elements that is spaced apart from the driver chip. 
     In an exemplary embodiment of the inventive concept, the display device may further include a touch unit provided between the encapsulation element and the optical element and a touch flexible circuit board electrically connected to the touch unit. The filling elements may include a first filling element and a second filling element, which are arranged in the first direction with the touch flexible circuit board interposed therebetween when viewed in a direction normal to the plane, and the first filling element and the second filling element may be spaced apart from the touch flexible circuit board. 
     According to an exemplary embodiment of the inventive concept, a display device may include a substrate element including an organic light emitting diode for generating light, an encapsulation element provided on the substrate element to seal the organic light emitting diode, a sealing element provided along edge regions of the encapsulation element, the sealing element connecting the encapsulation element to the substrate element and including an outer side surface adjacent to the organic light emitting diode and an inner side surface facing the outer side surface, a window element provided on the substrate element, an adhesive element provided on the encapsulation element, and a filling element provided between the window element and the substrate element and spaced apart from the adhesive element to cover the sealing element. 
     In an exemplary embodiment of the inventive concept, the filling element may be in contact with the outer side surface of the sealing element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the inventive concept will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings. 
         FIG.  1    is an exploded perspective view of a display device according to an exemplary embodiment of the inventive concept. 
         FIG.  2    is a sectional view illustrating a portion of the display device of  FIG.  1    according to an exemplary embodiment of the inventive concept. 
         FIG.  3    is an equivalent circuit diagram of a pixel according to an exemplary embodiment of the inventive concept. 
         FIG.  4    is a sectional view illustrating a portion of a display device according to an exemplary embodiment of the inventive concept. 
         FIG.  5    is a sectional view of a display device according to an exemplary embodiment of the inventive concept. 
         FIG.  6    is an enlarged sectional view illustrating a portion of a display device according to an exemplary embodiment of the inventive concept. 
         FIG.  7    is a sectional view of a display device according to an exemplary embodiment of the inventive concept. 
         FIG.  8    is a sectional view of a display device according to an exemplary embodiment of the inventive concept. 
         FIG.  9    is a plan view illustrating a portion of a display device according to an exemplary embodiment of the inventive concept. 
         FIG.  10    is a plan view illustrating a portion of a display device according to an exemplary embodiment of the inventive concept. 
         FIGS.  11 A and  11 B  are plan views, each of which illustrates a portion of a display device according to an exemplary embodiment of the inventive concept. 
         FIGS.  12 A and  12 B  are plan views, each of which illustrates a portion of a display device according to an exemplary embodiment of the inventive concept. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Exemplary embodiments of the inventive concept will now be described more fully with reference to the accompanying drawings. Exemplary embodiments of the inventive concept may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. In the drawings, the thicknesses of layers and regions may be exaggerated for clarity. Like reference numerals in the drawings may denote like elements, and thus, their description may be omitted. 
     It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. 
     As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
       FIG.  1    is an exploded perspective view of a display device according to an exemplary embodiment of the inventive concept.  FIG.  2    is a sectional view illustrating a portion of the display device of  FIG.  1    according to an exemplary embodiment of the inventive concept.  FIG.  3    is an equivalent circuit diagram of a pixel according to an exemplary embodiment of the inventive concept.  FIG.  4    is a sectional view illustrating a portion of a display device according to an exemplary embodiment of the inventive concept. Hereinafter, a display device  1000  according to an exemplary embodiment of the inventive concept will be described in more detail with reference to  FIGS.  1  to  4   . 
     Referring to  FIG.  1   , the display device  1000  may include a window element  100 , a container element  150 , a substrate element  200 , an encapsulation element  300 , a sealing element  400 , a filling element  500 , an optical element  600 , an adhesive element  700 , a flexible circuit board  800 , and a main circuit board  900 . 
     The window element  100  may be divided into a transmission region AA and a light-blocking region BA, when viewed in a plan view. For example, the plan view may be defined by a first direction DR 1  and a second direction DR 2 . The transmission region AA may be optically transparent. For example, the transmission region AA may have a transmittance of 90% or higher. Light emitted from the substrate element  200  may pass through the transmission region AA and may be recognized by an outer user. In other words, the light that passes through the transmission region AA may be viewed by a person looking at the display device  1000 . The light-blocking region BA may be adjacent to the transmission region AA. In the present embodiment, the light-blocking region BA may enclose the transmission region AA. However, the inventive concept is not limited thereto. For example, the light-blocking region BA may be provided near only one side of the transmission region AA. The light-blocking region BA may have various shapes. For example, the inventive concept is not limited to the shape of the light-blocking region BA shown in  FIG.  1   . 
     The container element  150  may have an internal space. The substrate element  200 , the encapsulation element  300 , the sealing element  400 , the filling element  500 , the optical element  600 , the adhesive element  700 , the flexible circuit board  800 , and the main circuit board  900  may be placed in the internal space of the container element  150 . The container element  150  may be coupled to the window element  100 . The container element  150  and the window element  100  may define the outside of the display device  1000 . 
     The filling element  500 , which is provided to support the window element  100  and the substrate element  200 , may also stably maintain a thickness of a gap region between the window element  100  and the substrate element  200 . Thus, the filling element  500  may help prevent the display device  1000  from being damaged by an external impact. 
     The substrate element  200  may include a base layer  210 , a circuit layer  220 , and a device layer  230 . The circuit layer  220  and the device layer  230  may be provided on the base layer  210 . The base layer  210  may include a glass substrate, a metal substrate, or a substrate made of an organic/inorganic composite material. 
     In exemplary embodiments of the inventive concept, the base layer  210  may further include a synthetic resin layer. The synthetic resin layer may include a thermosetting resin. 
     In addition, at least one inorganic layer, which is used as a barrier layer and/or a buffer layer, may be further provided on the base layer  210 . The inorganic layer may be formed of or include aluminum oxide, titanium oxide, silicon oxide, silicon oxynitride, zirconium oxide, or hafnium oxide. The inorganic layer may have a multi-layered structure. The multi-layered inorganic layers may be used as a barrier layer and/or a buffer layer. At least one of the barrier layer and the buffer layer may be omitted from the multi-layered structure. 
     The barrier layer may prevent an external foreign substance from passing through the barrier layer. The barrier layer may include a silicon oxide layer and a silicon nitride layer. The silicon oxide layer and the silicon nitride layer may be stacked in a sequential or an alternating manner. 
     The buffer layer may allow a layer, which is placed on or below the buffer layer, to have an increased coupling strength. The buffer layer may include a silicon oxide layer and a silicon nitride layer. The silicon oxide layer and the silicon nitride layer may be stacked alternatingly. 
     The circuit layer  220  and the device layer  230  may include a driver circuit GDC, a plurality of signal lines SGL, a plurality of pixels PX, and a plurality of signal pads. 
     The substrate element  200  may include a display region DA, which is provided to display an image produced by the pixels PX, and a non-display region NDA, which is provided adjacent to the display region DA. The display region DA may be overlapped with the transmission region AA of  FIG.  1   . The non-display region NDA may be overlapped with the light-blocking region BA of  FIG.  1   . 
     The driver circuit GDC may be configured to generate a plurality of scan signals and to sequentially output the scan signals to a plurality of scan lines GL. This will be described in more detail below. In addition, the driver circuit GDC may also be configured to output other control signals to the pixels PX. 
     The signal lines SGL may include scan lines GL, data lines DL, a power line PL, and a control signal line CSL. Each of the scan lines GL may be connected to the pixels PX, e.g., a corresponding row or rows of the pixels PX, and each of the data lines DL may be connected to the pixels PX, e.g., a corresponding column or columns of the pixels PX. The power line PL may be connected to the pixels PX. The control signal line CSL may be connected to a scan driver circuit and may be used to deliver control signals. At least one signal pad may be connected to a corresponding one of the signal lines SGL. 
       FIG.  3    is an equivalent circuit diagram of a pixel according to an exemplary embodiment of the inventive concept.  FIG.  3    illustrates a scan line GL, a data line DL, a power line PL, and a pixel PX connected to the scan, data and power lines GL, DL and PL. In an exemplary embodiment of the inventive concept, the pixel PX may include an organic light emitting diode or a quantum dot light emitting diode serving as a light emitting device. A luminescent layer of the organic light emitting diode may include an organic luminescent material. A luminescent layer of the quantum dot light emitting diode may include quantum dots and quantum rods. For simplicity, the description that follows will refer to an example in which an organic light emitting diode is used as the pixel PX. 
     The pixels PX may be classified into a plurality of groups, according to display colors of the pixels PX. For example, the pixels PX may include red pixels, green pixels, and blue pixels. In an exemplary embodiment of the inventive concept, the pixels PX may further include white pixels. 
     The pixel PX may include an organic light emitting diode OLED and a pixel driver circuit for driving the organic light emitting diode OLED. In the present embodiment, the pixel driver circuit may include a first thin-film transistor T 1  (or a driving transistor), a second thin-film transistor T 2  (or a switching transistor), and a capacitor Cst. A first power voltage ELVDD may be provided to the organic light emitting diode OLED. A second power voltage ELVSS may be lower than the first power voltage ELVDD. The second power voltage ELVSS may be connected to a terminal of the organic light emitting diode OLED. 
     The first thin-film transistor T 1  may be connected to the organic light emitting diode OLED. The first thin-film transistor T 1  may be used to control a driving current flowing through the organic light emitting diode OLED, depending on an amount of electric charges stored in the capacitor Cst. The second thin-film transistor T 2  may be configured to output a data signal applied to the data line DL, in response to a scan signal applied to the scan line GL. The capacitor Cst may be charged to have a voltage corresponding to the data signal to be output from the second thin-film transistor T 2 . 
     The structure of the pixel PX is not limited to that shown in  FIG.  3   . For example, the structure of the pixel PX may be variously changed. For example, the pixel driver circuit may include three or more thin-film transistors. 
       FIG.  4    is a sectional view illustrating a portion of a display device according to an exemplary embodiment of the inventive concept. An example of a display device will be described in more detail with reference to  FIGS.  1  and  4   . The sectional view of  FIG.  4    illustrates a portion of the pixel PX, taken along line I-I′ of  FIG.  2   . The first thin-film transistor T 1  and the organic light emitting diode OLED, which are parts of the pixel PX, are illustrated in  FIG.  4   . In addition,  FIG.  4    illustrates how the encapsulation element  300  and the sealing element  400  are placed on the substrate element  200 . 
     The first thin-film transistor T 1  may include a semiconductor, pattern SP, a control electrode GE, an input electrode SE, and an output electrode DE. The semiconductor pattern may be provided on the base layer  210 . The semiconductor pattern SP may be formed of or include a crystalline semiconductor material or an amorphous silicon. 
     A first insulating layer IL 1  may be provided on the base layer  210 . The first insulating layer IL 1  may be overlapped with a plurality of the pixels PX (e.g., see  FIG.  2   ) and cover the semiconductor patterns SP of the pixels PX. The first insulating layer IL 1  may be an inorganic layer and/or an organic layer and may have a single-or multi-layered structure. The first insulating layer IL 1  may be formed of or include aluminum oxide, titanium oxide, silicon oxide, silicon oxynitride, zirconium oxide, or hafnium oxide. 
     The control electrode GE may be provided on the first insulating layer IL 1 . The control electrode GE may be overlapped with the semiconductor pattern SP. 
     A second insulating layer IL 2  may be provided on the first insulating layer IL 1 . The second insulating layer IL 2  may cover the first insulating layer IL 1  and the control electrode GE. The second insulating layer IL 2  may be overlapped with the plurality of the pixels PX (e.g., see  FIG.  2   ). The second insulating layer IL 2  may be an inorganic layer and/or an organic layer and may have a single-or multi-layered structure. The second insulating layer IL 2  may be formed of or include aluminum oxide, titanium oxide, silicon oxide, silicon oxynitride, zirconium oxide, or hafnium oxide. 
     The input electrode SE and the output electrode DE may be provided on the second insulating layer IL 2 . Each of the input and output electrodes SE and DE may be connected to the semiconductor pattern SP through a corresponding one of contact holes CH 1  and CH 2 , which are formed in the insulating layers IL 1  and IL 2 . 
     A third insulating layer IL 3  may be provided on the second insulating layer IL 2  to cover the first thin-film transistor T 1 . The third insulating layer IL 3  may be an inorganic layer and/or an organic layer and may have a single-or multi-layered structure. The third insulating layer IL 3  may be formed of or include aluminum oxide, titanium oxide, silicon oxide, silicon oxynitride, zirconium oxide, or hafnium oxide. 
     The organic light emitting diode OLED may be provided on the third insulating layer IL 3 . The organic light emitting diode OLED may include a first electrode AE, a first charge control layer HCL, a luminescent layer EML, a second charge control layer ECL, and a second electrode CE. In the present embodiment, the first electrode AE may correspond to an anode electrode, and the second electrode may correspond to a cathode electrode CE of the organic light emitting diode OLED. The first charge control layer HCL may be hole control layer and second charge control layer ECL may be an electron control layer ECL. 
     However, the inventive concept is not limited to the above example. For example, the first electrode AE, the first charge control layer HCL, the luminescent layer EML, the second charge control layer ECL, and the second electrode CE may be used as a cathode electrode, an electron control layer, a luminescent layer, a hole control layer, and an anode electrode, respectively. 
     The first electrode AE may be connected to the output electrode DE through a third contact hole CH 3 , which is formed to penetrate the third insulating layer IL 3 . 
     A pixel definition layer PDL may be provided on the third insulating layer IL 3 . The pixel definition layer PDL may have an opening OP exposing at least a portion of the first electrode AE. The opening OP of the pixel definition layer PDL may define a light emitting region PXA of the pixel PX. Regions, in which the pixels PX are provided, may be referred to as ‘pixel regions’, and each of the pixel regions may include the light emitting region PXA and a non-light-emitting region NPXA adjacent to the light-emitting region PXA. The non-light-emitting region NPXA may enclose the light emitting region PXA. Each of the light emitting region PXA and the non-light-emitting region NPXA, which are provided in each of the pixels PX, may be overlapped with the display region DA shown in  FIG.  2   . 
     The first charge control layer HCL may be commonly provided in the light emitting region PXA and the non-light-emitting region NPXA. A common layer, such as the first charge control layer HCL, may cover a plurality of the pixels PX in common. The first charge control layer HCL may be used to control hole motion. For example, the first charge control layer HCL may include a hole transport layer and a hole injection layer. 
     The luminescent layer EML may be provided on the first charge control layer HCL. The luminescent layer EML may be locally provided on only a region corresponding to the opening P. For example, the luminescent layer EML may be divided into a plurality of patterns that are formed in the plurality of pixels PX, respectively. 
     The second charge control layer ECL may be provided on the luminescent layer EML. The second charge control layer ECL may be used to control electron motion. For example, the second charge control layer ECL may include an electron transport layer and an electron injection layer. 
     The second electrode CE may be provided on the second charge control layer ECL. The second electrode CE may be a common electrode or a negative electrode. 
     In the case where the organic light emitting diode OLED is a top-emission type organic light emitting diode OLED, the first electrode AE may be a reflective electrode and the second electrode CE may be a transparent or transflective electrode. In the case where the organic light emitting diode OLED is a bottom-emission type organic light emitting diode OLED, the first electrode AE may be a transparent or transflective electrode and the second electrode CE may be a reflective electrode. 
     The encapsulation element  300  may be provided on the substrate element  200 . The encapsulation element  300  may cover the display region DA. The encapsulation element  300  may be provided in the form of a glass or plastic substrate. However, the inventive concept is not limited thereto. For example, the encapsulation element  300  may be formed of or include organic or inorganic materials. 
     The substrate and encapsulation elements  200  and  300  may be connected to each other by the sealing element  400 . The sealing element  400  may be provided along edge regions of the encapsulation element  300 , which are parallel to the first direction DR 1  or the second direction DR 2 . In an exemplary embodiment of the inventive concept, when viewed in a plan view, the edge regions may be outer regions of the encapsulation element  300  overlapped with the non-display region NDA of the substrate element  200 . The sealing element  400  may include a frit. The sealing element  400 , along with the encapsulation element  300 , may prevent the organic light emitting diode OLED from being exposed to external moisture and air. 
     The sealing element  400  may have a specific thickness in an area between the substrate and encapsulation elements  200  and  300 . Thus, the substrate element  200 , the encapsulation element  300 , and the sealing element  400  may define an internal space INR. The internal space INR may be substantially maintained in a vacuum state. However, the inventive concept is not limited thereto, and the internal space INR may be filled with nitrogen gas (N 2 ) or an insulating material. In an exemplary embodiment of the inventive concept, the sealing element  400  may be overlapped with the non-display region NDA of  FIG.  2   . For example, the sealing element  400  may be provided between the substrate and encapsulation elements  200  and  300  and may be overlapped with the non-display region NDA, when viewed in a plan view. Although  FIG.  4    illustrates an example in which the sealing element  400  is directly provided on the second electrode CE, the inventive concept is not limited to this example. As an example, an insulating layer, which is formed of inorganic or organic materials, may be provided to cover the second electrode CE, and the sealing element  400  may be provided on the insulating layer covering the second electrode CE. Furthermore, in an exemplary embodiment of the inventive concept, the pixel definition layer PDL and the insulating layers IL 1 , IL 2 , and IL 3  may be omitted from a region corresponding to the non-display region NDA of  FIG.  4   . In this case, the sealing element  400  may be directly provided on the base layer  210 . 
     The filling element  500  may be provided between the window element  100  and the substrate element  200 . The filling element  500  may fill a gap region between the window element  100  and the substrate element  200 . In addition, since the filling element  500  is used to stably maintain a thickness of a gap region between the window element  100  and the substrate element  200 , the filling element  500  can be used to stably protect the device layer  230  from an external impact. The filling element  500  may be formed of or include an insulating material. For example, the filling element  500  may be formed of or include photo- or thermo-curable materials. The filling element  500  will be described in more detail below. 
     The optical element  600  may be provided between the window element  100  and the encapsulation element  300 . The optical element  600  may be overlapped with the transmission region AA. The optical element  600  may be configured to increase brightness of an image generated by the device layer  230  or to suppress visibility deterioration, which is caused by the reflection of external light. For example, the optical element  600  may include a polarization film, an optical compensation film, or a color filter. The adhesive element  700  may be provided between the optical element  600  and the window element  100 . The adhesive element  700  may be used to attach the window element  100  to the optical element  600 . The adhesive element  700  may be overlapped with the transmission region AA. 
     Accordingly, the adhesive element  700  may include a transparent adhesive material. For example, the adhesive element  700  may include an optical clear adhesive (OCA), an optical transparent resin (OCR), or a pressure sensitive adhesive (PSA). 
     The flexible circuit board  800  may include a flexible film  810  and a driver chip  820 . The flexible circuit board  800  may be provided near one side of the substrate element  200  and may include output pads, which are coupled to the signal pads. Thus, the flexible circuit board  800  may be used to electrically connect at least one of the signal lines SGL to the main circuit board  900 . 
     The flexible film  810  may have a flexible property and may include a plurality of circuit lines. 
     The driver chip  820  may be mounted on the flexible film  810  in a chip-on-film (COF) manner. The driver chip  820  may include driving devices (e.g., a data driver circuit) for driving the pixels PX. Although one flexible circuit board  800  is illustrated, the inventive concept is not limited thereto. For example, a plurality of flexible circuit boards  800  may be coupled to the substrate element  200 . 
     The main circuit board  900  may be coupled to input pads of the flexible circuit board  800  and may be electrically connected to at least one of the signal lines SGL through the flexible circuit board  800 . In an exemplary embodiment of the inventive concept, the main circuit board  900  may be a flexible printed circuit board (FPCB). 
     The main circuit board  900  may include a signal control unit (e.g., a timing controller). The signal control unit may be configured to receive input image signals and to convert the input image signals to image data suitable for operations of the pixels PX. In addition, the signal control unit may also be configured to receive a variety of control signals (e.g., a vertical synchronization signal, a horizontal synchronization signal, a main clock signal, and a data enable signal) and to output the control signals. 
       FIG.  5    is a sectional view of a display device according to an exemplary embodiment of the inventive concept.  FIG.  6    is an enlarged sectional view illustrating a portion of a display device according to an exemplary embodiment of the inventive concept. Hereinafter, the display device  1000  will be described with reference to  FIGS.  5  and  6   . In the following description, the sealing element  400  is illustrated in an enlarged manner. 
     In the present embodiment, a first region A 1  and a second region A 2  may be defined in the substrate element  200 . A portion of the first region A 1  may not be covered by the encapsulation element  300  and a portion of the first region A 1  may be overlapped with a portion of the filling element  500 . The second region A 2  may be adjacent to the first region A 1  in the second direction DR 2  and may be covered with the encapsulation element  300 . 
     A third region A 3  and a fourth region A 4  may be defined in the encapsulation element  300 . The third region A 3  may not be covered by the optical element  600  and may be overlapped with a portion of the filling element  500 . The fourth region A 4  may be adjacent to the third region A 3  in the second direction DR 2  and may be covered with the optical element  600 . In the present embodiment, the filling element  500  may be overlapped with a portion of each of the window and substrate elements  100  and  200 . The filling element  500  may be spaced apart from the optical element  600  and the adhesive element  700 . 
     In the present embodiment, a light-blocking layer BM may be provided on the light-blocking region BA. The light-blocking layer BM may be formed of or include a black material. The light-blocking layer BM may be provided under the window element  100  and may be formed by a printing or deposition process. In an exemplary embodiment of the inventive concept, the filling element  500  may be overlapped with the light-blocking layer BM and may be overlapped with a portion of each of the first region A 1  and the third region A 3 . When measured in the second direction DR 2 , a width W 1  (hereinafter, a first width) of the filling element  500  may be greater than a width W 2  (hereinafter, a second width) of the sealing element  400 . When viewed in a plan view, the filling element  500  may cover the sealing element  400 . 
     As shown in  FIG.  6   , a bottom surface  500 C (or bottom area) of the filling element  500  may be in direct contact with a portion of a top surface  300 A, a side surface  300 B, and a portion of a bottom surface  300 C of the encapsulation element  300 . In addition, the bottom surface  500 C (or bottom area) of the filling element  500  may be in direct contact with an outer side surface  400 A of the sealing element  400 , and a portion of a top surface  200 A of the substrate element  200 . In the present embodiment, an inner side surface  400 D of the sealing element  400  facing the outer side surface  400 A, along with the substrate and encapsulation elements  200  and  300 , may define the internal space INR that is hermetically sealed. In other words, the inner side surface  400 D may be closer to the organic light emitting diode OLED (e.g., see  FIG.  4   ) than the outer side surface  400 A. 
     Since the display device  1000  includes the filling element  500  that is in direct contact with the outer side surface  400 A of the sealing element  400 , it is possible to prevent the sealing element  400  from having a weakened adhesion strength due to an external impact or a foreign substance. In addition, since the display device  1000  includes the filling element  500  that is in direct contact with the outer side surface  400 A of the sealing element  400 , it is possible to prevent the substrate element  200  and the encapsulation element  300  from being decoupled from each other due to the cracking of the sealing element  400 . In addition, since the filling element  500  is used to maintain a gap region between the substrate element  200  and the window element  100 , it is possible to increase a mechanical strength of the display device  1000 . 
     During a fabrication process, there may be a difference in curing levels and materials between the filling and adhesive elements  500  and  700 . Thus, in the case where the filling element  500  is in partial contact with the adhesive element  700 , due to a difference in refractive index between a contacting portion and a non-contacting portion, the contacting portion may be recognized by an external user. Such recognition by the external user is unwanted. According to an exemplary embodiment of the inventive concept, since the filling element  500  is provided adjacent to the adhesive element  700 , it is possible to prevent the filling and adhesive elements  500  and  700 , which are formed of different materials, from being mixed with each other in a curing step. Therefore, the contacting portion is prevented from being recognized by a user. As a result, it is further possible to provide the display device  1000  with increased reliability. 
       FIG.  7    is a sectional view of a display device according to an exemplary embodiment of the inventive concept. Hereinafter, an element previously described with reference to  FIGS.  1  to  6    identified by the same reference number in  FIG.  7    may not be repeatedly described. In an exemplary embodiment of the inventive concept, a filling element  500 - 1  may be overlapped with a portion of the light-blocking region BA of the window element  100  and portions of the substrate and encapsulation elements  200  and  300 . The filling element  500 - 1  may partially cover a top surface  800 A and a side surface  800 C of the flexible circuit board  800 . In the present embodiment, since the filling element  500 - 1  covers the flexible circuit board  800 , it is possible to prevent an external foreign substance from entering the display device  1000  and to increase a mechanical strength of the display device  1000 . 
       FIG.  8    is a sectional view of a display device according to an exemplary embodiment of the inventive concept. Hereinafter, an element previously described with reference to  FIGS.  1  to  6    identified by the same reference number in  FIG.  8    may not be repeatedly described. 
     According to an exemplary embodiment of the inventive concept, a display device  1000 - 1  may further include a driver chip DI. In the present embodiment, the driver chip DI may include driving devices (e.g., a data driver circuit) fix driving the pixels PX. 
     In the present embodiment, a filling element  500 - 2  may be provided to partially cover a top surface DI-A and a side surface DI-C of the driver chip DI. However, the inventive concept is not limited to this example. For example, the filling element  500 - 2  may be provided to wholly cover the driver chip DI. Since the filling element  500 - 2  is provided to partially or wholly cover the sealing element  400  and the driver chip DI, it is possible to increase a mechanical strength of the display device  1000 - 1 . 
       FIG.  9    is a plan view illustrating a touch unit of a display device according to an exemplary embodiment of the inventive concept. 
     A touch unit TU may be configured to obtain information on coordinates of an external input. The touch unit TU may be directly provided on the encapsulation element  300 . In an exemplary embodiment of the inventive concept, the touch unit TU may be directly formed on the encapsulation element  300 . Accordingly, an additional adhesive layer between the touch unit TU and the encapsulation element  300  may be omitted. However, the inventive concept is not limited thereto. For example, the touch unit TU may be provided in the form of an individual panel and may be coupled to the encapsulation element  300  through an additional adhesive element. 
     The touch unit TU may include a touch sensor, in which a plurality of conductive layers are provided, and a plurality of insulating layers. Each of the insulating layers may have a single-layered structure or a multi-layered structure including layers, which are stacked in a third direction DR 3 . 
     The touch unit TU may include an active region AR, which is used to sense an external input corresponding to the transmission region AA of  FIG.  1   , and a non-active region NAR, which is provided to surround the active region AR. The active region AR and the non-active region NAR may correspond to the transmission region AA and the light-blocking region BA, respectively, of  FIG.  1   . 
     One of the conductive layers of the touch sensor may include first sensing electrodes IE 1  and first signal lines SL 1 , which are connected to the first sensing electrodes IE 1 , and another conductive layer of the touch sensor may include second sensing electrodes IE 2  and second signal lines SL 2 , which are connected to the second sensing electrodes IE 2 . 
     The first sensing electrodes IE 1  and the second sensing electrodes IE 2  may cross each other. The first sensing electrodes IE 1  may be arranged in the second direction DR 2 , and each of the first sensing electrodes IE 1  may be extended in the first direction DR 1 . The touch unit TU may be configured to sense an external input in a mutual-capacitance and/or self-capacitance manner. 
     Each of the first sensing electrodes IE 1  may include first sensor units SP 1  and first connecting portions CP 1 . Each of the second sensing electrodes IE 2  may include second sensor units SP 2  and second connecting portions CP 2 . 
     In an exemplary embodiment of the inventive concept, the first sensing electrodes IE 1  and the second sensing electrodes IE 2  may have a shape (e.g., a bar shape), in which the sensor unit and the first and second connecting portions CP 1  and CP 2  are not distinguished. The first sensor units SP 1  and the second sensor units SP 2  are illustrated to have a diamond shape, but the inventive concept is not limited thereto. For example, at least one of the first and second sensor units SP 1  and SP 2  may have a polygonal shape. 
     The first signal lines SL 1  and the second signal lines SL 2  may be overlapped with the active region AR and the non-active region NAR. The first signal lines SL 1  and the second signal lines SL 2  may be connected to corresponding touch pads TD, respectively. 
       FIGS.  10  to  12 B  are plan views, each of which illustrates a portion of a display device according to an exemplary embodiment of the inventive concept. Hereinafter, an element previously described with reference to  FIGS.  1  to  5    identified by the same reference number in  FIGS.  10  to  12 B  may not be repeatedly described. 
     In an exemplary embodiment of the inventive concept, the display device  1000  may further include a touch flexible circuit board TF, which is coupled to the touch pads TD of  FIG.  9   . The touch flexible circuit board TF may be provided at an edge region of the encapsulation element  300  (e.g., the third region A 3  of  FIG.  5   ) and may be used to electrically connect the touch unit TU to the main circuit board  900  (e.g., see  FIG.  1   ). The touch flexible circuit board TF may have a flexible property and may include a plurality of circuit lines. The touch flexible circuit board TF may be used to deliver touch sensing signals from the main circuit board  900  to the touch unit TU. 
     In an exemplary embodiment of the inventive concept, a plurality of filling elements  500 - 3  may be provided, as shown in  FIG.  10   . The filling elements  500 - 3  may include a first filling element  501  and a second filling element  502 , which are spaced apart from each other with the touch flexible circuit board TF interposed therebetween. Each of the first and second filling elements  501  and  502  may be spaced apart from the touch flexible circuit board TF by a separation space OZ. The filling elements and the touch flexible circuit board TF in  FIGS.  11 A to  12 B  may be arranged in the same manner as those described with reference to  FIG.  10   . Accordingly, descriptions thereof may be omitted below. 
     In the present embodiment, since the touch flexible circuit board TF is not in contact with the first and second filling elements  501  and  502 , it is possible to prevent or suppress a material of the first and second filling elements  501  and  502  from entering a space between the touch flexible circuit board TF and the substrate element  200  due to a capillary phenomenon, which may occur when the first and second filling elements  501  and  502  are formed. 
     In an exemplary embodiment of the inventive concept, a plurality of filling elements  500 - 4  may be provided, as shown in  FIG.  11 A . For example, the filling elements  500 - 4  may include a third filling element  503  and a fourth filling element  504 , which are spaced apart from each other with the touch flexible circuit board TF interposed therebetween, and a fifth filling element  505 . The fourth filling element  504  may be overlapped with the driver chip DI (e.g., see also  FIG.  8   ), when viewed in the second direction DR 2 . However, the fourth filling element  504  and the driver chip DI may be spaced apart from each other, when viewed in a plan view. When measured in the second direction DR 2 , a third width W 3  of the fourth filling element  504  may be smaller than a fourth width W 4  of the fifth filling element  505 . 
     The adhesive element  700  (e.g., see  FIG.  1   ) may be cured by ultraviolet light incident through the side surface of the display device  1000 . The ultraviolet light may be incident through a space between the driver chip DI and the window element  100 . In this case, a transmission amount of the ultraviolet light may be decreased depending on a thickness of the driver chip DI. In the present embodiment, a width of the fourth filling element  504  (e.g., W 3 ) overlapped with the driver chip DI in the second direction DR 2  may be decreased. In this case, it is possible to reduce the transmission amount of the ultraviolet light, which is caused by the thickness of the driver chip DI, and thereby to suppress a reduction in a curing rate of the adhesive element  700 . 
     Referring to  FIG.  11 B , a plurality of filling elements  500 - 4 A may include a third filling element  503 A, a fourth filling element  504 A, and a fifth filling element  505 A. At least a portion of the fourth filling element  504 A is overlapped with the driver chip DI when viewed in a plan view. In addition, when viewed in a plan view, the fourth filling element  504 A may fully cover the driver chip DI. Thus, it is possible to prevent a foreign substance from entering the driver chip DI. Furthermore, since at least a portion of the driver chip DI is covered with the fourth filling element  504 A, it is possible to increase a mechanical strength of the display device  1000 . 
     In an exemplary embodiment of the inventive concept, as shown in  FIG.  12 A , filling elements  500 - 5  may be dot-shaped patterns, and at least two (e.g.,  508  and  506 ) of the filling elements  500 - 5  may be spaced apart from each other with the touch flexible circuit board TF interposed therebetween. The dot-shaped filling elements  500 - 5  may have different shapes. In the present embodiment, the filling elements  500 - 5  may include sixth filling elements  506 , which are overlapped with the driver chip DI in the second direction DR 2 , and a seventh filling element  507 , which is not overlapped with the driver chip DI. When measured in the first direction DR 1 , a distance (hereinafter, a fifth width W 5 ) between the sixth filling elements  506  may be larger than a distance (hereinafter, a sixth width W 5 ) between the seventh filling element  507  and one of the sixth filling elements  506  adjacent to the seventh filling element  507 . 
     Referring to  FIG.  12 B , a plurality of filling elements  500 - 5 A may include sixth filling elements  506 A, seventh filling elements  507 A and eighth filling elements  508 A. At least a portion of sixth filling elements  506 A is overlapped with the driver chip DI, when viewed in a plan view. In addition, when viewed in a plan view, at least one of the sixth filling elements  506 A may fully cover the driver chip DI. Thus, it is possible to prevent a foreign substance from entering the driver chip DI. Furthermore, since at least a portion of the driver chip DI is covered with the sixth filling elements  506 A, it is possible to increase a mechanical strength of the display device  1000 . 
     The adhesive element  700  (e.g., see  FIG.  1   ) may be cured by ultraviolet light incident through the side surface of the display device  1000 . The ultraviolet light may be incident through a space between the driver chip DI and the window element  100 . Here, a distance between the filling elements  500 - 5 A overlapped with the driver chip DI may be increased. Therefore, it is possible to reduce the transmission amount of the ultraviolet light, due to the thickness of the driver chip DI, and to suppress a reduction in a curing rate of the adhesive element  700 . 
     According to exemplary embodiments of the inventive concept, it is possible to stably maintain a thickness of a gap region between a window element  100  and a substrate element  200  and thereby to stably protect a device layer  230  from an external impact. Furthermore, it is possible to protect a sealing element  400 , which is used to connect the substrate element  200  to an encapsulation element  300 , and to prevent a display device  1000  from failure due to external moisture or contamination. As a result, it is possible to increase operation reliability of the display device  1000 . 
     While the inventive concept has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by one of ordinary skill in the art that variations in form and detail may be made thereto without departing from the spirit and scope of the inventive concept as defined by the attached claims.