Patent Publication Number: US-2021193964-A1

Title: Display Apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of the Korean Patent Application No. 10-2019-0172132 filed on Dec. 20, 2019, which is hereby incorporated by reference as if fully set forth herein. 
     BACKGROUND 
     Field of the Invention 
     The present disclosure relates to a display apparatus. 
     Discussion of the Related Art 
     With the advancement of information-oriented society, various requirements for display apparatuses for displaying an image are increasing. Therefore, various display apparatuses such as liquid crystal display (LCD) apparatuses, plasma display panels (PDPs), and organic light emitting display apparatuses are being used recently. 
     Organic light emitting display apparatuses among display apparatuses are self-emitting display apparatuses and do not need a separate backlight. Therefore, in comparison with LCD apparatuses, the organic light emitting display apparatuses may be implemented to be lightweight and thin and to have low power consumption. Also, the organic light emitting display apparatuses are driven with a direct current (DC) low voltage, have a fast response time, and have low manufacturing cost. 
     However, organic light emitting devices are easily degraded by external causes such as external water and oxygen. In order to prevent such a problem, an encapsulation layer is formed on an organic light emitting device so as to prevent external water and oxygen from penetrating into the organic light emitting device. 
     The encapsulation layer may be formed to include an organic layer, for example, an adhesive layer provided on the organic light emitting device. In this case, a side surface of the encapsulation layer may be exposed to the outside, and external water and oxygen may flow in through a side surface of the organic layer. The external water and oxygen flowing in through a side surface of the organic layer may damage the organic light emitting device to cause a defect in a display apparatus. 
     SUMMARY 
     Accordingly, the present disclosure is directed to providing a display apparatus that substantially obviates one or more problems due to limitations and disadvantages of the related art. 
     An aspect of the present disclosure is directed to providing a display apparatus in which an encapsulation function is enhanced, and thus, the penetration of external water and oxygen is minimized. 
     Additional advantages and features of the disclosure will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the disclosure. The objectives and other advantages of the disclosure may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     To achieve these and other advantages and in accordance with the purpose of the disclosure, as embodied and broadly described herein, there is provided a display apparatus including a substrate, a light emitting device provided on the substrate, a first adhesive layer provided on the light emitting device to cover the light emitting device, and a first encapsulation substrate provided on the first adhesive layer, wherein a side surface of the first adhesive layer is covered by the first encapsulation substrate. 
     It is to be understood that both the foregoing general description and the following detailed description of the present disclosure are exemplary and explanatory and are intended to provide further explanation of the disclosure as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiments of the disclosure and together with the description serve to explain the principle of the disclosure. In the drawings: 
         FIG. 1  is a cross-sectional view illustrating a display apparatus according to a first embodiment of the present disclosure; 
         FIG. 2  is a cross-sectional view illustrating a display apparatus according to a second embodiment of the present disclosure; 
         FIG. 3  is a plan view illustrating a plurality of grooves formed in a first encapsulation substrate, according to the second embodiment of the present disclosure; 
         FIG. 4  is a plan view illustrating a modification example of the plurality of grooves shown in  FIG. 3 ; 
         FIG. 5  is a cross-sectional view illustrating an example of the plurality of grooves taken along line I-I′ of  FIG. 3 ; and 
         FIGS. 6A to 6D  are cross-sectional views illustrating a process of forming a first adhesive layer and a first encapsulation substrate, according to a preferable example of the first embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     Reference will now be made in detail to the exemplary embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     Advantages and features of the present disclosure, and implementation methods thereof will be clarified through following embodiments described with reference to the accompanying drawings. The present disclosure may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. Further, the present disclosure is only defined by scopes of claims. 
     A shape, a size, a ratio, an angle, and a number disclosed in the drawings for describing embodiments of the present disclosure are merely an example, and thus, the present disclosure is not limited to the illustrated details. Like reference numerals refer to like elements throughout. In the following description, when the detailed description of the relevant known function or configuration is determined to unnecessarily obscure the important point of the present disclosure, the detailed description will be omitted. In a case where ‘comprise’, ‘have’, and ‘include’ described in the present specification are used, another part may be added unless ‘only-’ is used. The terms of a singular form may include plural forms unless referred to the contrary. 
     In construing an element, the element is construed as including an error range although there is no explicit description. 
     In describing a position relationship, for example, when a position relation between two parts is described as ‘on˜’, ‘over˜’, ‘under˜’ and ‘next˜’, one or more other parts may be disposed between the two parts unless ‘just’ or ‘direct’ is used. 
     In describing a time relationship, for example, when the temporal order is described as ‘after˜’, ‘subsequent˜’, ‘next˜’, and ‘before˜’ a case which is not continuous may be included unless ‘just’ or ‘direct’ is used. 
     It will be understood that, although the terms “first”, “second”, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure. 
     A first horizontal axis direction, a second horizontal axis direction, and a vertical axis direction should not be construed as only a geometric relationship where a relationship therebetween is vertical, and may denote having a broader directionality within a scope where elements of the present disclosure operate functionally. 
     An X axis direction, a Y axis direction, and a Z axis direction should not be construed as only a geometric relationship where a relationship therebetween is vertical, and may denote having a broader directionality within a scope where elements of the present disclosure operate functionally. 
     In describing the elements of the present disclosure, terms such as first, second, A, B, (a), (b), etc., may be used. Such terms are used for merely discriminating the corresponding elements from other elements and the corresponding elements are not limited in their essence, sequence, or precedence by the terms. It will be understood that when an element or layer is referred to as being “on” or “connected to” another element or layer, it can be directly on or directly connected to the other element or layer, or intervening elements or layers may be present. Also, it should be understood that when one element is disposed on or under another element, this may denote a case where the elements are disposed to directly contact each other, but may denote that the elements are disposed without directly contacting each other. 
     The term “at least one” should be understood as including any and all combinations of one or more of the associated listed elements. For example, the meaning of “at least one of a first element, a second element, and a third element” denotes the combination of all elements proposed from two or more of the first element, the second element, and the third element as well as the first element, the second element, or the third element. 
     Features of various embodiments of the present disclosure may be partially or overall coupled to or combined with each other, and may be variously inter-operated with each other and driven technically as those skilled in the art can sufficiently understand. The embodiments of the present disclosure may be carried out independently from each other, or may be carried out together in co-dependent relationship. 
     Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In adding reference numerals to elements of each of the drawings, although the same elements are illustrated in other drawings, like reference numerals may refer to like elements. Also, for convenience of description, a scale of each of elements illustrated in the accompanying drawings differs from a real scale, and thus, is not limited to a scale illustrated in the drawings. 
     Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. 
     First Embodiment 
       FIG. 1  is a cross-sectional view illustrating a display apparatus according to a first embodiment of the present disclosure. Hereinafter, an example where a display apparatus according to an embodiment of the present disclosure is an organic light emitting display apparatus will be mainly described, but the present disclosure is not limited thereto. 
     Referring to  FIG. 1 , the display apparatus according to the first embodiment of the present disclosure may include a substrate  100 , a circuit device layer  200 , a light emitting device  300 , a first adhesive layer  410 , and a first encapsulation substrate  510 . 
     The substrate  100  may be a plastic film, a glass substrate, or a silicon wafer substrate formed through a semiconductor process. The substrate  100  may include a transparent material, or may include an opaque material. 
     The display apparatus according to the first embodiment of the present disclosure may be implemented as a bottom emission type where emitted light travels toward the substrate. In this case, the substrate  100  may include a transparent material. Also, the display apparatus according to the first embodiment of the present disclosure may be implemented as a top emission type where emitted light travels away from the substrate. In this case, the substrate  100  may include an opaque material. 
     The circuit device layer  200  may be formed on the substrate  100 . A circuit device including various signal lines, a thin film transistor (TFT), and a capacitor may be included in the circuit device layer  200 . The signal lines may include a gate line, a data line, a power line, and a reference line, and the TFT may include a switching TFT, a driving TFT, and a sensing TFT. 
     The switching TFT may be turned on based on a gate signal supplied through the gate line and may transfer a data voltage, supplied through the data line, to the driving TFT. 
     The driving TFT may be turned on based on the data voltage supplied through the switching TFT and may generate a data current from power supplied through the power line to supply the data current to the light emitting device. 
     The sensing TFT may sense a threshold voltage deviation of the driving TFT causing the degradation in image quality and may transfer a current of the driving TFT to the reference line in response to a sensing control signal supplied through the gate line of the sensing TFT or a separate sensing line. 
     The capacitor may hold the data voltage supplied through the driving TFT during one frame and may be connected to each of a gate terminal and a source terminal of the driving TFT. 
     A contact hole may be provided in the circuit device layer  200 , and thus, the source terminal or a drain terminal of the driving TFT may be exposed through the contact hole. 
     The light emitting device  300  may be formed on the circuit device layer  200 . The light emitting device  300  may include a first electrode  310 , a bank  320 , a light emitting layer  330 , and a second electrode  340 . 
     The first electrode  310  may be formed on the circuit device layer  200 . The first electrode  310  may be connected to the source terminal or the drain terminal of the driving TFT through the contact hole. The first electrode  310  may include a transparent material, or may include an opaque material. 
     In a case where the display apparatus according to the first embodiment of the present disclosure is implemented as the bottom emission type, the first electrode  310  may include a transparent conductive material (TCO), such as indium tin oxide (ITO) or indium zinc oxide (IZO), or a semi-transmissive conductive material such as magnesium (Mg), silver (Ag), or an alloy of Mg and Ag. 
     In a case where the display apparatus according to the first embodiment of the present disclosure is implemented as the top emission type, the first electrode  310  may include a metal material, which is high in reflectance, such as a stacked structure (titanium/aluminum/titanium (Ti/Al/Ti)) of Al and Ti, a stacked structure (ITO/Al/ITO) of Al and ITO, an APC alloy, or a stacked structure (ITO/APC/ITO) of an APC alloy and ITO. In this case, the APC alloy may be an alloy of silver (Ag), palladium (Pb), and copper (Cu). 
     The bank  320  may be formed on the first electrode  310  and may define an emission area. An electric field may not be formed between the first electrode  310  and the second electrode  340 , in a region where the bank  320  is formed, and thus, light may not be emitted. 
     The bank  320  may be implemented as an organic layer such as acryl resin, epoxy resin, phenolic resin, polyamide resin, or polyimide resin. Alternatively, the bank  320  may be implemented as an inorganic layer such as silicon nitride, aluminum nitride, zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride, silicon oxide, aluminum oxide, or titanium oxide. 
     The light emitting layer  330  may be formed on the first electrode  310 . The light emitting layer  330  may be formed on the bank  340 . 
     The light emitting layer  330  may include a hole transporting layer, an organic light emitting layer, and an electron transporting layer. In this case, when a voltage is applied to the first electrode  310  and the second electrode  340 , a hole and an electron may respectively move to the light emitting layer  330  through the hole transporting layer and the electron transporting layer and may be combined in the light emitting layer  330  to emit light. 
     The light emitting layer  330  may include a white light emitting layer emitting white light. Alternatively, the light emitting layer  330  may include at least one of a red light emitting layer emitting red light, a green light emitting layer emitting green light, and a blue light emitting layer emitting blue light. 
     The second electrode  340  may be formed on the light emitting layer  330 . The second electrode  340  may include a transparent material, or may include an opaque material. 
     In a case where the display apparatus according to the first embodiment of the present disclosure is implemented as the bottom emission type, the second electrode  340  may include a metal material, which is high in reflectance, such as a stacked structure (titanium/aluminum/titanium (Ti/Al/Ti)) of Al and Ti, a stacked structure (ITO/Al/ITO) of Al and ITO, an APC alloy, or a stacked structure (ITO/APC/ITO) of an APC alloy and ITO. In this case, the APC alloy may be an alloy of silver (Ag), palladium (Pb), and copper (Cu). 
     In a case where the display apparatus according to the first embodiment of the present disclosure is implemented as the top emission type, the second electrode  340  may include a transparent conductive material (TCO), such as indium tin oxide (ITO) or indium zinc oxide (IZO), or a semi-transmissive conductive material such as magnesium (Mg), silver (Ag), or an alloy of Mg and Ag. 
     A capping layer  350  may be formed on the second electrode  340  and may protect the second electrode  340 . The capping layer  350  may be implemented as a multilayer where one or more inorganic layers of silicon oxide (SiOx), silicon nitride (SiNx), and/or silicon oxynitride (SiON) are alternately stacked. 
     The first adhesive layer  410  may be provided on the capping layer  350  and the light emitting device  300  and may be formed to cover the capping layer and the light emitting device  300 . Moreover, the first adhesive layer  410  may be formed to contact the substrate  100 . Therefore, the first adhesive layer  410  functions as an encapsulation layer. 
     According to the first embodiment of the present disclosure, a side surface  410   a  of the first adhesive layer  410  may be covered by the first encapsulation substrate  510 . Accordingly, at least one portion of the side surface  410   a  of the first adhesive layer  410  is not exposed to the outside and the penetration of external water and oxygen may be reduced, and an encapsulation function of the display apparatus may be enhanced. 
     Hereinafter, a preferable example according to the first embodiment of the present disclosure where the side surface of the first adhesive layer is convex will be mainly described. As shown in the cross section of  FIG. 1 , a side surface  410   a  of the first adhesive layer  410  may be formed to be convex, and a top surface  410   b  of the first adhesive layer  410  may be flat or convex. More specifically, a reference line L, which is a virtual rectilinear line that passes through a center C of the light emitting device  300  and is vertical to the substrate  100 , may be set. In this case, a distance between the reference line L and a contact point  410   c  between the side surface  410   a  and the top surface  410   b  of the first adhesive layer  410  may be set to be less than a distance between the reference line L and a contact point  410   e  between the side surface  410   a  of the first adhesive layer  410  and the substrate  100 . Also, a distance between the reference line L and a peak end  410   d  of the side surface  410   a  of the first adhesive layer  410  may be set to be greater than a distance between the reference line L and the contact point  410   e  between the side surface  410   a  of the first adhesive layer  410  and the substrate  100 . Accordingly, a region between the peak end  410   d  of the side surface  410   a  of the first adhesive layer  410  and the contact point  410   e  between the side surface  410   a  of the first adhesive layer  410  and the substrate  100  may have a shape which is rolled toward the reference line L. It should be noted that, the contact point  410   c  refers to a contact line between the side surface and the top surface of the first adhesive layer, and the contact point  410   e  refers to a contact line between the side surface of the first adhesive layer and the substrate  100 , extending in a direction perpendicular to the cross section shown in  FIG. 1 . 
     The first adhesive layer  410  may include an organic material. 
     The first adhesive layer  410  may include acryl resin, epoxy resin, phenolic resin, polyamide resin, polyimide resin, or olefin. 
     The first adhesive layer  410  may be formed by a vapor deposition process, a printing process, or a slit coating process, which uses an organic material, but is not limited thereto and the first adhesive layer  410  may be formed by an ink-jet process. 
     The first adhesive layer  410  may include a water-absorbing material and a hydrogen-absorbing material. The water-absorbing material and the hydrogen-absorbing material may each be one of alkali metal, alkali earth metal, an inert compound of alkali metals, and an inert compound of alkali earth metals. Accordingly, water flowing in from the outside and hydrogen occurring in the inside may be absorbed by the first adhesive layer  410 , and thus, the light emitting device  300  may be prevented from being damaged by water and hydrogen. 
     The first encapsulation substrate  510  may be provided on the first adhesive layer  410  and cover the side surface  410   a  of the first adhesive layer  410 . 
     The first encapsulation substrate  510  may contact the first adhesive layer  410  and may be bent along the side surface  410   a  of the first adhesive layer  410 . In detail, the first encapsulation substrate  510  may contact the side surface  410   a  of the first adhesive layer  410  as well as the top surface  410   b  of the first adhesive layer  410 , and thus, an exposed portion of the side surface  410   a  of the first adhesive layer  410  through which external water and oxygen penetrate into the display apparatus may be reduced. Accordingly, the penetration of external water and oxygen may be minimized, and an encapsulation function of the display apparatus may be enhanced. 
     The first encapsulation substrate  510  may cover all of the side surface  410   a  and the top surface  410   b  of the first adhesive layer  410 . Therefore, the first encapsulation substrate  510  may contact the substrate  100 . Also, the side surface  410   a  and the top surface  410   b  of the first adhesive layer  410  may be completely occluded by the first encapsulation substrate  510 , and thus, may not be exposed to the outside. 
     Alternatively, the first encapsulation substrate  510  may cover all of the top surface  410   b  of the first adhesive layer  410 , but may expose a portion of the side surface  410   a  of the first adhesive layer  410 . Therefore, the first encapsulation substrate  510  may not contact the substrate  100 . Also, a region, which is adjacent to the substrate  100 , of the side surface  410   a  of the first adhesive layer  410  may not be occluded by the first encapsulation substrate  510  and may be exposed to the outside. 
     The first encapsulation substrate  510  may be formed by attaching metal, on which a rolling process has been performed, to an upper portion of the first adhesive layer  410 . Also, the first encapsulation substrate  510  may be formed of a thin film including at least one metal of aluminum (Al), copper (Cu), and invar, but is not limited thereto. 
     The above description relates to a preferable example where the side surface of the first adhesive layer is convex, but the present disclosure is not limited thereto. For example, it is contemplated the side surface of the first adhesive layer may be flat or concave or irregular, as long as the side surface of the first adhesive layer is covered by the first encapsulation substrate. Thus, detailed description with respect to other separate shapes of the side surface of the first adhesive layer is omitted. 
     Second Embodiment 
       FIG. 2  is a cross-sectional view illustrating a display apparatus according to a second embodiment of the present disclosure. 
     Referring to  FIG. 2 , the display apparatus according to the second embodiment of the present disclosure may include a substrate  100 , a circuit device layer  200 , a light emitting device  300 , a first adhesive layer  410 , a second adhesive layer  420 , a first encapsulation substrate  510 , and a second encapsulation substrate  520 . 
     The substrate  100 , the circuit device layer  200 , the light emitting device  300 , the first adhesive layer  410 , and the first encapsulation substrate  510  configuring the display apparatus according to the second embodiment of the present disclosure may be substantially the same as the substrate  100 , the circuit device layer  200 , the light emitting device  300 , the first adhesive layer  410 , and the first encapsulation substrate  510  configuring the display apparatus according to the second embodiment of the present disclosure, and thus, their detailed description are omitted. 
     Hereinafter, an example where the display apparatus according to the second embodiment of the present disclosure is an organic light emitting display apparatus will be mainly described, but the present disclosure is not limited thereto. 
     The second adhesive layer  420  may be provided on the first encapsulation substrate  510  and may be formed to cover the first encapsulation substrate  510  and contact the substrate  100 . Also, when a side surface  410   a  of the first adhesive layer  410  is exposed by the first encapsulation substrate  510 , the second adhesive layer  420  may be formed to cover all of the exposed portion of the first adhesive layer  410  and the first encapsulation substrate  510 . Accordingly, the first adhesive layer  410  may not be exposed to the outside. 
     Hereinafter, a preferable example according to the second embodiment of the present disclosure where the side surface of the second adhesive layer is convex will be mainly described. As shown in the cross section of  FIG. 2 , a side surface  420   a  of the second adhesive layer  420  may be formed to be convex, and a top surface  420   b  of the second adhesive layer  420  may be flat or convex. More specifically, a distance between a reference line L and a contact point  420   c  between the side surface  420   a  and a top surface  420   b  of the second adhesive layer  420  may be set to be less than a distance between the reference line L and a contact point  420   e  between the side surface  420   a  of the second adhesive layer  420  and the substrate  100 . Also, a distance between the reference line L and a peak end  420   d  of the side surface  420   a  of the second adhesive layer  420  may be set to be greater than a distance between the reference line L and the contact point  420   e  between the side surface  420   a  of the second adhesive layer  420  and the substrate  100 . Accordingly, a region between the peak end  420   d  of the side surface  420   a  of the second adhesive layer  420  and the contact point  420   e  between the side surface  420   a  of the second adhesive layer  420  and the substrate  100  may have a shape which is rolled toward the reference line L. similarly as the contact points  410   c ,  410   e , the contact points  420   c ,  420   e  each refer to a contact line, and their detailed description is omitted. 
     The second adhesive layer  420  may include an organic material. 
     The second adhesive layer  420  may include acryl resin, epoxy resin, phenolic resin, polyamide resin, polyimide resin, or olefin. 
     The second adhesive layer  420  may be formed by a vapor deposition process, a printing process, or a slit coating process, which uses an organic material, but is not limited thereto and the second adhesive layer  420  may be formed by an ink-jet process. 
     The second adhesive layer  420  may include a water-absorbing material and a hydrogen-absorbing material. 
     The second adhesive layer  420  may include the water-absorbing material. The water-absorbing material may be one of alkali metal, alkali earth metal, an inert compound of alkali metals, and an inert compound of alkali earth metals. Accordingly, water flowing in from the outside may be absorbed by the second adhesive layer  420 , and thus, the light emitting device  300  may be prevented from being damaged by water and hydrogen. 
     Because the display apparatus according to the second embodiment of the present disclosure further includes the second adhesive layer  420 , water and oxygen flowing in from the outside may be distributed and diffused to the second adhesive layer  420  and even to the first adhesive layer  410 . That is, not all of water and oxygen flowing in from the outside may be diffused to the first adhesive layer  410  only. Accordingly, compared with the first embodiment of the present disclosure, as the amount of external water and oxygen diffused to the first adhesive layer  410  may be decreased, the final amount of water and oxygen penetrating into the light emitting device  300  covered by the first adhesive layer  410  may also decrease. Accordingly, the damage of the light emitting device  300  caused by external water and oxygen may be minimized. 
     The second encapsulation substrate  520  may be provided on the second adhesive layer  420  and cover the side surface  420   c  of the second adhesive layer  420 . 
     The second encapsulation substrate  520  may contact the second adhesive layer  420  and may be bent along the side surface  420   a  of the second adhesive layer  420 . In detail, the second encapsulation substrate  520  may contact the side surface  420   a  of the second adhesive layer  420  as well as the top surface  420   b  of the second adhesive layer  420 , and thus, an exposed portion of the second adhesive layer  420  through which external water and oxygen penetrates into the display apparatus may be reduced. Also, the first adhesive layer  410  and the first encapsulation substrate  510  may not be externally exposed by the second adhesive layer  420  and the second encapsulation substrate  520 , and thus, compared with the first embodiment, a speed at which external water and oxygen penetrate into the display apparatus may be more reduced, thereby enhancing an encapsulation function of the display apparatus. 
     The second encapsulation substrate  520  may cover all of the side surface  420   a  and the top surface  420   b  of the second adhesive layer  420 . Therefore, the second encapsulation substrate  520  may contact the substrate  100 . Also, the side surface  420   a  and the top surface  420   b  of the second adhesive layer  420  may be completely occluded by the second encapsulation substrate  520 , and thus, may not be exposed to the outside. 
     Alternatively, the second encapsulation substrate  520  may cover all of the top surface  420   b  of the second adhesive layer  420 , but may expose a portion of the side surface  420   a  of the second adhesive layer  420 . Therefore, the second encapsulation substrate  520  may not contact the substrate  100 . Also, a region, which is adjacent to the substrate  100 , of the side surface  420   a  of the second adhesive layer  420  may not be occluded by the second encapsulation substrate  520  and may be exposed to the outside. 
     The second encapsulation substrate  520  may be formed by attaching metal, on which a rolling process has been performed, to an upper portion of the second adhesive layer  420 . Also, the second encapsulation substrate  520  may be formed of a thin film including at least one metal of aluminum (Al), copper (Cu), and invar, but is not limited thereto. 
     The above description relates to a preferable example where the side surface of the second adhesive layer is convex, but the present disclosure is not limited thereto. For example, it is contemplated the side surface of the second adhesive layer may be flat or concave or irregular, as long as the side surface of the second adhesive layer is covered by the second encapsulation substrate. Thus, detailed description with respect to other separate shapes of the side surface of the second adhesive layer is omitted. 
       FIG. 3  is a plan view illustrating a plurality of grooves  515  formed in a first encapsulation substrate  510 , according to the second embodiment of the present disclosure,  FIG. 4  is a plan view illustrating a modification example of the plurality of grooves shown in  FIG. 3 , and  FIG. 5  is a cross-sectional view illustrating an example of the plurality of grooves taken along line I-I′ of  FIG. 3 . 
     The display apparatus according to the second embodiment of the present disclosure may include a plurality of grooves  515  formed in an upper portion of the first encapsulation substrate  510  contacting the second adhesive layer  420 . 
     As illustrated in  FIG. 3 , each of the plurality of grooves  515  may be formed in the form of a rectilinear line, and the rectilinear line may be formed in a first direction which is parallel to a contact line (i.e., the contact point  420   c  as shown in  FIG. 2 ) between the side surface and the top surface of the first encapsulation substrate  510  when the first encapsulation substrate  510  is bent. Accordingly, when the first encapsulation substrate  510  is bent in a horizontal direction along a side surface of the first adhesive layer  410 , stress occurring in an upper portion of the first encapsulation substrate  510  may decrease. 
     Moreover, as illustrated in  FIG. 4 , the plurality of grooves  515  may include a plurality of grooves  515  formed in a rectilinear shape in a first direction and a plurality of grooves  515  formed in a rectilinear shape in a second direction perpendicular to the first direction. Therefore, compared with the first encapsulation substrate  510  of  FIG. 3 , the plurality of grooves  515  formed in a rectilinear shape in the second direction perpendicular to the first direction may be further provided, and thus, when the first encapsulation substrate  510  is bent at an upper side, an lower side, a left side and a right side thereof along a side surface of the first adhesive layer  410 , stress occurring in the upper portion of the first encapsulation substrate  510  may be more reduced. 
     Moreover, the plurality of grooves  515  may be formed in an area of the upper portion of the first encapsulation substrate  510  in which bending occurs, not in all of the upper portion of the first encapsulation substrate  510 . 
     Moreover, as illustrated in  FIG. 5 , a cross-sectional surface of each of the plurality of grooves  515  may be formed in a V-shape, but is not limited thereto. In a case where the cross-sectional surface of each of the plurality of grooves  515  is formed in a V-shape, when the first encapsulation substrate  510  is bent, stress occurring in the upper portion of the first encapsulation substrate  510  may be reduced, and moreover, external water may be prevented from penetrating through the plurality of grooves  515  of the first encapsulation substrates  510 . 
     Additionally, in a case where a plurality of grooves  515  are formed in an upper portion of the second encapsulation substrate  520 , each of the plurality of grooves  515  may be a path through which external water and oxygen penetrate into the display apparatus, due to an external impact applied to the second encapsulation substrate  520 . Accordingly, in order to prevent such a problem, a groove may not be formed in a top surface of the second encapsulation substrate  520 . 
       FIGS. 6A to 6D  are cross-sectional views illustrating a process of forming a first adhesive layer  410  and a first encapsulation substrate  510 , according to the first embodiment of the present disclosure. Hereinafter, a preferable example of the process for forming the first adhesive layer and the first encapsulation substrate where the side surface of the first adhesive layer is convex will be mainly described, but the present disclosure is not limited thereto. 
     As illustrated in  FIG. 6A , the first encapsulation substrate  510  may be provided on the first adhesive layer  410 . A protection film (not shown) for protecting the first adhesive layer  410  may be attached on a lower portion of the first adhesive layer  410 . The protection film (not shown) may be formed to include polyethylene terephthalate (PET), but is not limited thereto. The first encapsulation substrate  510  may be formed by attaching metal, on which a rolling process has been performed, to an upper portion of the first adhesive layer  410 . 
     As illustrated in  FIG. 6B , a fixed frame  610  and a blade  620  may be disposed. The fixed frame  610  and the blade  620  may be disposed at positions apart from an upper portion of the first encapsulation substrate  510  in a vertical direction. The fixed frame  610  may overlap the upper portion of the first encapsulation substrate  510 , and a portion of an edge of the upper portion of the first encapsulation substrate  510  may be exposed. The blade  620  may be disposed at a position apart from an end of the fixed frame  610 . 
     As illustrated in  FIG. 6C , the blade  620  may upward and downward move to cut the first adhesive layer  410  and the first encapsulation substrate  510 . At this time, a region which does not overlap the fixed frame  610  may be separated from each of the first adhesive layer  410  and the first encapsulation substrate  510 . As a result, a side surface  410   a  of the first adhesive layer  410  may be formed to be convex, and a top surface  410   b  of the first adhesive layer  410  may be flat or convex. Also, the first encapsulation substrate  510  may contact the first adhesive layer  410  and may be formed to be bent along the side surface  410   a  of the second adhesive layer  410 . 
     As illustrated in  FIG. 6D , the fixed frame  610  and the blade  620  may be removed. Also, the first adhesive layer  410  and the first encapsulation substrate  510  separated from each other by the blade  620  may be removed. Also, a substrate  100  with a circuit device layer  200  and a light emitting device  300  formed therein may be bonded to the first adhesive layer  410  and the first encapsulation substrate  510 , thereby manufacturing a display apparatus. 
     The present disclosure is not limited to the above process and many other processes may be used for forming the first adhesive layer and the first encapsulation substrate with other separate shapes of side surfaces, such as, flat, concave and irregular, for example, by virtue of different shapes and motion manners of the blade. Moreover, the first encapsulation substrate may be separately formed with a corresponding shape to the side surface of the first adhesive layer and then assembled with the first adhesive layer. 
     A process for forming a first adhesive layer  410 , a first encapsulation substrate  510 , a second adhesive layer  420  and a second encapsulation substrate  520  according to the second embodiment of the present disclosure may be similar to the process with respect to the first embodiment, and thus its detailed description is omitted. 
     According to the present disclosure, a first encapsulation substrate may contact a first adhesive layer and cover a side surface of the first adhesive layer, and thus, the penetration of external water and oxygen through the side surface of the first adhesive layer may be prevented, thereby enhancing an encapsulation function of a display apparatus. 
     Moreover, according to the present disclosure, a second adhesive layer may be further provided and may block and absorb water and oxygen flowing in from the outside, and thus, the amount of water and oxygen flowing in through the first adhesive layer may be reduced, thereby decreasing the amount of water and oxygen penetrating into an organic light emitting device. 
     Moreover, according to the present disclosure, the second adhesive layer and a second encapsulation substrate may be further provided, and a plurality of grooves may be formed in an upper portion of the first encapsulation substrate contacting the second adhesive layer, thereby decreasing a stress occurring in the upper portion of the first encapsulation substrate when the first encapsulation substrate is bent. 
     The above-described feature, structure, and effect of the present disclosure are included in at least one embodiment of the present disclosure, but are not limited to only one embodiment. Furthermore, the feature, structure, and effect described in at least one embodiment of the present disclosure may be implemented through combination or modification of other embodiments by those skilled in the art. Therefore, content associated with the combination and modification should be construed as being within the scope of the present disclosure. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the spirit or scope of the disclosures. Thus, it is intended that the present disclosure covers the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.