Patent Publication Number: US-2021193963-A1

Title: Display Apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of the Korean Patent Application No. 10-2019-0174276 filed on Dec. 24, 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. 
     Heat occurs when an organic light emitting display apparatus is being driven, and causes a reduction in performance of the organic light emitting display apparatus. Therefore, an inner plate, a back cover and other components are additionally required and separately coupled for heat dissipation and rigidity of an organic light emitting device. However, an organic light emitting display apparatus in the related art may give negative effect to its weight, thickness, and structures; and consumers are keep demanding a display apparatus having an optimized balance in its structure and performance (such as in light weight, thickness, durability, heat dissipation, driving performances and etc.). 
     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 having enhanced heat dissipation performance and having an optimized balance in its slim and light structure. 
     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 comprising a display area with a light emitting device disposed therein and a non-display area surrounding the display area, an adhesive layer covering the light emitting device, a heat dissipation substrate provided on the adhesive layer, a pad part provided in the non-display area of the substrate, a circuit film electrically connected to the pad part, and a printed circuit board disposed on the heat dissipation substrate and electrically connected to the circuit film, wherein the heat dissipation substrate is disposed in the outermost portion of the display apparatus. 
     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; 
         FIGS. 3A and 3B  are rear and exploded perspective views illustrating the display apparatus according to the second embodiment of the present disclosure, respectively; 
         FIG. 4  is a front perspective view illustrating the display apparatus according to the first and second embodiments of the present disclosure; and 
         FIG. 5  is a table showing heat dissipation performance of a display apparatus with respect to the thickness and the material of metal. 
     
    
    
     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. 
       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. Hereinafter, an example where the display apparatus according to the first and second embodiments 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  FIGS. 1 and 2 , the display apparatus according to the first and second embodiments 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 metal layer  510 , and a first circuit cover  740 . 
     The substrate  100  may be divided into a display area DA and a non-display area NDA. The display area DA may be an area which emits light by using the light emitting device  300 , and the non-display area NDA may be formed to surround the display area DA. 
     The substrate  100  may be a plastic film, a glass substrate, or a silicon wafer substrate formed through a semiconductor process. 
     The display apparatus according to the first and second embodiments 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. For example, the substrate  100  may include a top surface and a bottom surface (or a light output surface) opposite to the top surface. 
     The circuit device layer  200  may be formed on the top surface of 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 , a second electrode  340 , and a capping layer  350 . 
     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 and second embodiments 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. 
     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 move to the light emitting layer  330  through the hole transporting layer and the electron transporting layer, respectively, 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 and second embodiments 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/fi)) of Al and Ti, a stacked structure (ITO/Al/ITO) of Al and ITO, an APC alloy, and 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 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  350  and the light emitting device  300 . 
     The first adhesive layer  410  may be formed to have a sufficient thickness, for preventing particles from penetrating into the light emitting device  300 . 
     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 second adhesive layer  420  may be provided on the first adhesive layer  410 . 
     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 getter  425  which absorbs water and hydrogen. The getter  425  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 and hydrogen flowing in from the outside may be absorbed by the getter  425  in the second adhesive layer  420 , and thus, the light emitting device  300  may be prevented from being damaged by water and hydrogen. 
     The first metal layer  510  may be provided on the second adhesive layer  420 . The first metal layer  510  is directly attached to the substrate by the first and second adhesive layer, each having parallel surfaces. 
     The first metal layer  510  may protect the light emitting device  300  from the outside and may discharge heat, occurring in the light emitting device  300 , to the outside, thereby enhancing the performance of the light emitting device  300 . Accordingly, the first metal layer  510  may be referred to as a heat dissipation layer or a heat dissipation substrate. 
     A bottom surface of the first metal layer  510  may be formed to be bigger than or equal to a top surface of the second adhesive layer  420 . Also, the top surface of the second adhesive layer  420  may not be externally exposed by the bottom surface of the first metal layer  510 . Accordingly, an area, exposed to the outside, of the getter  425  of the second adhesive layer  420  may be minimized, thereby decreasing a speed at which the getter  425  is oxidized. 
     The first metal layer  510  may include Al, but is not limited thereto. For example, the first metal layer  510  may include one or more materials of stainless steel, Al, a magnesium (Mg) alloy, a magnesium-lithium (Mg—Li) alloy, and an Al alloy, but is not limited thereto. 
     The display apparatus according to the first and second embodiments of the present disclosure may further include a resin layer  600 , a second metal layer  520 , and a pad part  710 . 
     Referring to  FIG. 1 , a resin layer  600  according to the first embodiment may be provided in the non-display area NDA of the substrate  100 . For example, the resin layer  600  may additionally cover a portion of one side surface of the first metal layer  510  adjacent to the pad part  710 . For example, the resin layer  600  may additionally cover the first adhesive layer  410  which passes over one side surface of the first metal layer  510  and protrudes or overflows toward the pad part  710 . In this case, a thickness of the first metal layer  510  may be larger than or equal to 3.0 mm—for securing the heat dissipation performance of the display apparatus. 
     Referring to  FIG. 2 , a resin layer  600  according to the second embodiment may be provided in the display area DA and the non-display area NDA. 
     The resin layer  600  may be formed to cover the circuit device layer  200 , the light emitting device  300 , the first adhesive layer  410 , the second adhesive layer  420 , and the first metal layer  510 . Therefore, the resin layer  600  may transfer, to the second metal layer  520 , heat occurring in the light emitting device  300  and heat discharged from the first metal layer  510 , thereby enhancing the heat dissipation performance of the display apparatus. For better heat dissipation performance and slim and light structure, the second metal layer is directly attached to the first metal layer by the resin layer, each having parallel surfaces, and the resin layer may be provided on the first metal layer  510  in the display area DA and only in a portion of the non-display area NDA, not exceeding an area of a top surface of the first metal layer  510 . 
     In order to secure heat transfer performance, a thickness of the resin layer  600  between the first metal layer  510  and the second metal layer  520  may be larger than or equal to 0.1 mm or about 0.3 mm, but is not limited thereto. For example, the resin layer  600  may be thinner than the first metal layer  510  in the display area DA and may be thicker than the first metal layer  510  in the non-display area NDA. 
     According to the second embodiment, when a thickness of the first metal layer  510  is in the range of 0.1 mm to 0.3 mm, a thickness of the resin layer  600  between the first metal layer  510  and the second metal layer  520  may be larger than or equal to 0.3 mm. In this case, the resin layer  600  may be thicker than a thickness of the first metal layer  510  in the display area DA and in the non-display area NDA. 
     The second metal layer  520  may be provided on the resin layer  600 . The first metal layer  510 , the resin layer  600 , and the second metal layer  520  as a whole may function or referred to as a heat dissipation substrate. 
     Heat transferred to the resin layer  600  may be discharged to the outside of the display apparatus by the second metal layer  520 , thereby enhancing the performance of the display apparatus. Additionally, the resin layer  600  may include a heat transferring material or a thermal conductive particle for transferring heat of the first metal layer  510  to the second metal layer  520 . The second metal layer  520  and the resin layer  600  may be formed to have the same area as that of the substrate  100 , but it is not limited thereto. The top surface of the substrate  100  may not be exposed to the outside. Accordingly, a thickness of an edge of the display apparatus may increase, and thus, the damage to the display apparatus caused by external pressure may be minimized. 
     The second metal layer  520  may be formed to include Al, but is not limited thereto. 
     A thickness of the second metal layer  520  may be thicker than that of the first metal layer  510  for better heat dissipation and rigidity of the display apparatus, and thus, the second metal layer may be referred to as a protection substrate. When the second metal layer  520  is formed to include Al, a thickness of the second metal layer  520  may be in the range of 2.0 mm to 2.5 mm for securing the heat dissipation performance of the second metal layer  520 , but is not limited thereto. 
     The pad part  710  may be provided in the non-display area NDA and may be provided at one edge of the substrate  100 . 
     The pad part  710  may be covered by the resin layer  600 . Therefore, the pad part  710  may not be exposed to the outside, thereby preventing a stripping defect and blocking an impact applied from the outside. Also, heat occurring in the pad part  710  may be transferred to the second metal layer  520  by the resin layer  600 , and thus, may be discharged to the outside of the display apparatus. 
     A plurality of electrodes connected to the circuit device layer  200  may be formed in the pad part  710 . 
     A conductive film  710   a  may be formed on a top surface of the pad part  710 . Accordingly, the pad part  710  may be electrically connected to a circuit film  730  through the conductive film  710   a . For example, the conductive film  710   a  may be an anisotropic conductive film. 
     The display apparatus according to the first and second embodiments of the present disclosure may further include a printed circuit board (PCB)  720 , a circuit film  730 , and a first circuit cover  740 . 
     Referring to  FIG. 1 , in the first embodiment, the PCB  720  may be provided on the first metal layer  510  and may provide various signals for driving the display apparatus. 
     The conductive film  720   a  may be formed on a top surface of the PCB  720 . Therefore, the PCB  720  may be electrically connected to the circuit film  730  through the conductive film  720   a . In this case, a thickness of the first metal layer  510  may be larger than or equal to 3.0 mm, and the pad part  710  may be formed to be covered by the first adhesive layer  410  or the second adhesive layer  420 , or may be formed on the substrate  100  uncovered by the first adhesive layer  410 . 
     A first adhesive member  720   b  may be provided on a bottom surface of the PCB  720 . Therefore, the PCB  720  may be attached to the first metal layer  510 . For example, the first adhesive member  720   b  may be disposed between the PCB  720  and the first metal layer  510 . Accordingly, the PCB  720  may be attached on the first metal layer  510  by the first adhesive member  720   b.    
     A second adhesive member  720   c  may be provided in an area, where the conductive film  720   a  is not provided, of the top surface of the PCB  720 . Therefore, the first circuit cover  740  may be attached to the PCB  720 . For example, the second adhesive member  720   c  may be disposed between the PCB  720  and the first circuit cover  740 . Accordingly, the first circuit cover  740  may be attached to the PCB  720  by the second adhesive member  720   c.    
     One side of the circuit film  730  may be electrically connected to the conductive film  710   a  of the pad part  710 , and the another side thereof may be electrically connected to the conductive film  720   a  of the PCB  720 . That is, the pad part  710  may be electrically connected to the PCB  720  by the circuit film  730 . 
     In detail, the circuit film  730  may be provided on a top surface of the conductive film  710   a  of the pad part  710  and may be implemented to pass through the resin layer  600  of the non-display area NDA and to extend firstly toward the outside of the display apparatus. Also, the circuit film  730  may be bent inwardly and extend along a side surface of the resin layer  600 , a top surface of the resin layer  600 , a side surface of the first metal layer  510 , and a top surface of the first metal layer  510 . In this case, the circuit film  730  may be apart from the first metal layer  510  not to contact the first metal layer  510 . Also, an end of the circuit film  730  which is bent inwardly may be provided on a top surface of the conductive film  720   a  of the PCB  720 . Therefore, according to the present disclosure, the damage to the circuit film  730  caused by an end of the first metal layer  510  and stress occurring on the surface of the circuit film  730  when the circuit film  730  is bent may be reduced compared to a structure of a related art circuit film where the circuit film formed on the top surface of the pad part is implemented to extend directly toward the inside of the display apparatus from the non-display area NDA to the display area DA without extending firstly toward the outside of the display apparatus. Also, the stability of the circuit film  730  may be secured, and thus, a thickness of the first metal layer  510  may increase, thereby enhancing the heat dissipation performance of the display apparatus. Furthermore, a thickness of the first metal layer  510  may increase so that a back cover or an inner plate fundamentally included in the display apparatus is replaced by or integrated into the first metal layer  510 , thereby providing a display apparatus including no back cover or inner plate. Accordingly, the first metal layer  510  may be disposed at an outermost portion of the display apparatus, and the circuit film  730  may contact the PCB  720  provided on the first metal layer  510 . 
     Referring to  FIG. 2 , in the second embodiment, the PCB  720  may be provided on the second metal layer  520  and may provide various signals for driving the display apparatus. 
     A first adhesive member  720   b  may be provided on the bottom surface of the PCB  720 . Therefore, the PCB  720  may be attached to the second metal layer  520 . For example, the first adhesive member  720   b  may be disposed between the PCB  720  and the second metal layer  520 . Accordingly, the PCB  720  may be attached to the second metal layer  520  by the first adhesive member  720   b.    
     One side of the circuit film  730  may be electrically connected to the conductive film  710   a  of the pad part  710 , and the another side thereof may be electrically connected to the conductive film  720   a  of the PCB  720 . That is, the pad part  710  may be electrically connected to the PCB  720  by the circuit film  730 . 
     In detail, the circuit film  730  may be provided on a top surface of the conductive film  710   a  of the pad part  710  and may be implemented to pass through the resin layer  600  of the non-display area NDA and to extend firstly toward the outside of the display apparatus. Also, the circuit film  730  may be bent inwardly and extend along a side surface of the resin layer  600 , a side surface of the second metal layer  520 , and a top surface of the second metal layer  520 . In this case, the circuit film  730  may be apart from the second metal layer  520  not to contact the second metal layer  520 . Also, an end of the circuit film  730  which is bent inwardly may be provided on a top surface of the conductive film  720   a  of the PCB  720 . Therefore, according to the present disclosure, the damage to the circuit film  730  caused by an end of the second metal layer  520  and stress occurring on the surface of the circuit film  730  when the circuit film  730  is bent may be reduced compared to the structure of the related art circuit film  730  where the circuit film  730  formed on the top surface of the pad part  710  is implemented to extend directly toward the inside of the display apparatus from the non-display area NDA to the display area DA without extending firstly toward the outside of the display apparatus. Also, the stability of the circuit film  730  may be secured, and thus, the thickness of the second metal layer  520  may increase, thereby enhancing the heat dissipation performance of the display apparatus. Furthermore, the thickness of the second metal layer  520  may increase so that a back cover or an inner plate fundamentally included in the display apparatus is replaced by or integrated into the second metal layer  520 , thereby providing a display apparatus including no back cover or inner plate. Accordingly, the second metal layer  520  may be disposed at an outermost portion of the display apparatus, and the circuit film  730  may contact the PCB  720  provided on the second metal layer  520 . 
     The circuit film  730  may be attached to the pad part  710  and the PCB  720  by a tape automated bonding (TAB) process. One side of the circuit film  730  connected to the pad part  710  may be covered by the resin layer  600 . For example, the resin layer  600  may cover and surround the pad part  710  and the one side of the circuit film  730  connected to the pad part  710 . 
     The circuit film  730  may include a tape carrier package (TCP) or a chip on film (or a chip on flexible board) (COF). 
     The circuit film  730  may include a driving integrated circuit (IC)  730   a . The driving IC  730   a  may be a data driver IC or a driver IC for driving the display apparatus, but is not limited thereto. 
     The first circuit cover  740  may be attached to a bottom surface of the substrate  100  and may be implemented to extend along the circuit film  730 . In this case, the first circuit cover  740  may be apart from the circuit film  730  not to contact the circuit film  730 . Accordingly, the first circuit cover  740  may prevent an external impact from being applied to the circuit film  730 . 
     The first circuit cover  740  may be implemented to cover a bottom edge (or a light output surface) of the substrate  100  overlapping the pad part  710 . The first circuit cover  740  according to the second embodiment may include a front cover portion  741  which covers the bottom edge of the substrate  100  overlapping the pad part  710 , a side cover portion  742  which extends (or is bent) to be vertical from the front cover portion  741  and covers a side surface of each of the substrate  100 , the resin layer  600 , and the second metal layer  520 , and a rear cover portion  743  which extends (or is bent) to be vertical from the side cover portion  742  toward the second metal layer  520  and covers the circuit film  730  and the PCB  720 . Similarly, the first circuit cover  740  according to the first embodiment may include the front cover portion  741  which covers the bottom edge of the substrate  100  overlapping the pad part  710 , the side cover portion  742  which extends (or is bent) to be vertical from the front cover portion  741  and covers a side surface of each of the substrate  100 , the resin layer  600 , and the first metal layer  510 , and a rear cover portion  743  which extends (or is bent) to be vertical from the side cover portion  742  toward the first metal layer  520  and covers the circuit film  730  and the PCB  720 . 
     The first circuit cover  740  may be attached to the PCB  720  by the second adhesive member  720   c . For example, the second adhesive member  720   c  may be disposed between the rear cover portion  743  of the first circuit cover  740  and the PCB  720 . 
     According to the second embodiment, a coupling portion  740   a  may be provided at an end of the first circuit cover  740  overlapping the second metal layer  520 , and a fixing pin  745  may be provided on a top surface of the second metal layer  520 . The fixing pin  745  may be provided in a region, which does not overlap the PCB  720  and the circuit film  730 , of the top surface of the second metal layer  520 . The coupling portion  740   a  may have a shape where a side surface thereof protrudes, and a groove may be provided in an upper portion of the fixing pin  745 . Therefore, the first circuit cover  740  may be fixed to the top surface of the second metal layer  520  by coupling of the fixing pin  745  and the coupling portion  740   a  of the first circuit cover  740 . It should be noted that, the coupling portion  740   a  and the fixing pin  745  as described above may also be applied in the first embodiment and the redundant description is omitted. 
       FIGS. 3A and 3B  are rear and exploded perspective views illustrating the display apparatus according to the second embodiment of the present disclosure, respectively. 
       FIG. 3A  is a rear perspective view illustrating the display apparatus according to the second embodiment of the present disclosure. As illustrated in  FIG. 3A , a second metal layer  520  covers a rear surface of the display apparatus and may be disposed at an outermost portion of the display apparatus thereby replacing or integrating a back cover or an inner plate. The first circuit cover  740  may be provided on a top surface of the second metal layer  520  and a bottom surface of a substrate  100 , and a second circuit cover  750  may be provided on the top surface of the second metal layer  520 . 
       FIG. 3B  is an exploded perspective view illustrating the display apparatus according to the second embodiment of the present disclosure and is a perspective view illustrating an example where the first circuit cover  740  and the second circuit cover  750  in  FIG. 3A  are separated from each other. 
     A plurality of PCBs  720 , a control PCB  725 , a plurality of circuit films  730 , a plurality of control circuit films  735 , and a plurality of fixing pins  745  may be provided on a top surface of the second metal layer  520 . 
     The control PCB  725  may be electrically connected to the plurality of PCBs  720  through the plurality of control circuit films  735  (or a signal cable). One side of each of the plurality of control circuit films  735  may be connected to the control PCB  725 , and the other sides of the plurality of control circuit films  735  may be respectively connected to the plurality of PCBs  720 . Therefore, the control PCB  725  may supply the plurality of PCBs  720  with a signal for driving the display apparatus. For example, the control PCB  725  may be referred to as a control board. 
     The plurality of PCBs  720  may be electrically connected to the plurality of pad parts  710  through the plurality of circuit films  730 . One side of each of the plurality of circuit films  730  may be connected to the PCB  720 , and the other sides of the plurality of driving circuit films  730  may be respectively connected to the plurality of pad parts  710 . Therefore, the PCB  720  may transfer a signal, supplied from the control PCB  725 , to the plurality of pad parts  710 . For example, each of the plurality of PCBs  720  may be referred to as a source PCB or a data PCB. 
     The first circuit cover  740  may be implemented to cover the plurality of circuit films  730  and the plurality of PCBs  720 . For example, the first circuit cover  740  may cover the plurality of PCBs  720 , the plurality of circuit films  730  connected to the plurality of PCBs  720 , and the plurality of fixing pins  745 . 
     The second circuit cover  750  may be implemented to cover the control PCB  725 . For example, the second circuit cover  750  may cover the control PCB  725  and the plurality of control circuit films  735  connected to the control PCB  725 . 
     The first circuit cover  740  may be attached to the bottom surface of the substrate  100  by adhesive material. 
     Alternatively, the first circuit cover  740  may be fixed to the top surface of the second metal layer  520  through coupling of the coupling portion  740   a  and the fixing pin  745 . In detail, the plurality of fixing pins  745  may be provided in a region between two PCBs  720  adjacent to each other, a region between two circuit films  730  adjacent to each other, and a region apart from an end of the PCB  720 , on a top surface of the second metal layer  520 , but is not limited thereto. Also, when the first circuit cover  740  is provided on the plurality of PCBs  720  and the plurality of circuit films  730 , the coupling portion  740   a  may be provided at a position, corresponding to the fixing pin  745 , of the first circuit cover  740 . Therefore, the first circuit cover  740  may be conveniently attached/detached on/from the top surface of the second metal layer  520  through coupling of the coupling portion  740   a  and the fixing pin  745 . 
     Moreover, the second circuit cover  750  may be conveniently attached/detached on/from the top surface of the second metal layer  520  through coupling of a coupling portion (not shown) and a fixing pin (not shown) on the basis of the same coupling manner as the first circuit cover  740  and may also be attached on the top surface of the second metal layer  520  by using an adhesive material. It should be noted that the first circuit cover  740  and the second circuit cover  750  as described above may also be applied in the first embodiment and the redundant description is omitted 
       FIG. 4  is a front perspective view illustrating the display apparatus according to the first and second embodiments of the present disclosure. 
     The substrate  100  may include a top surface including the pad part  710  and a light output surface opposite the top surface, and in  FIG. 4 , the light output surface is illustrated. As described above, the first circuit cover  740  may include the front cover portion  741 , the side cover portion  742 , and the rear cover portion  743 , and the front cover portion  741  may cover an edge of the light output surface of the substrate  100  overlapping the pad part  710 . 
       FIG. 5  is a table showing heat dissipation performance of a display apparatus with respect to a thickness and a material of metal. 
     As shown in  FIG. 5 , each column of the table shows the heat dissipation performance of the display apparatus with respect to the kind of metal encapsulating the display apparatus. In a case where invar, stainless steel (SUS), and Al are used for heat dissipation of the display apparatus under a condition where thicknesses are the same, it may be seen that the front temperature and the rear temperature of the display apparatus are lowest when Al is used. That is, the heat dissipation performance of Al is highest, among invar, stainless steel (SUS), and Al. 
     Moreover, as shown in  FIG. 5 , each row of the table shows the heat dissipation performance of the display apparatus with respect to the thickness of metal encapsulating the display apparatus. In a case where a thickness is changed to 0.08 mm, 0.2 mm, 0.5 mm, and 2.0 mm and the same metal is used for dissipating heat of the display apparatus, it may be seen that the front temperature and the rear temperature of the display apparatus are lowered as the thickness increases. That is, as the thickness of metal increases, the heat dissipation performance of the display apparatus is enhanced. 
     Therefore, the first metal layer  510  and the second metal layer  520  according to the present disclosure may include Al which is best in heat dissipation performance. Also, the heat dissipation performance of Al is not enhanced when Al has a certain thickness or more. Accordingly, in order to secure the most effective heat dissipation performance, when the second metal layer  520  includes Al, the thickness of the second metal layer  520  may be in the range of 2.0 mm to 2.5 mm. 
     A display apparatus according to the present disclosure will be described below. 
     A display apparatus according to an embodiment of the present disclosure includes a substrate comprising a display area with a light emitting device disposed therein and a non-display area surrounding the display area, an adhesive layer covering the light emitting device, a heat dissipation substrate provided on the adhesive layer, a pad part provided in the non-display area of the substrate, a circuit film electrically connected to the pad part, and a printed circuit board disposed on the heat dissipation substrate and electrically connected to the circuit film, wherein the heat dissipation substrate is disposed in the outermost portion of the display apparatus. 
     According to some embodiments of the present disclosure, the display apparatus further comprises a resin layer provided in at least the non-display area of the substrate to cover the pad part and one end of the circuit film connected to the pad part. 
     According to some embodiments of the present disclosure, the resin layer additionally covers at least a portion of one side surface of the first metal layer adjacent to the pad part, and/or additionally covers the adhesive layer which passes over the one side surface of the first metal layer and protrudes toward the pad part. 
     According to some embodiments of the present disclosure, the circuit film extends toward the printed circuit board along a side surface of the resin layer, a side surface of the first metal layer, and a top surface of the first metal layer. 
     According to some embodiments of the present disclosure, the resin layer additionally covers the light emitting device, the adhesive layer and the first metal layer, and the display apparatus further comprises a second metal layer provided on the resin layer. 
     According to some embodiments of the present disclosure, the circuit film extends toward the printed circuit board along a side surface of the resin layer, a side surface of the second metal layer, and a top surface of the second metal layer. 
     According to some embodiments of the present disclosure, the adhesive layer includes a first adhesive layer covering the light emitting device and a second adhesive layer provided on the first adhesive layer. 
     According to some embodiments of the present disclosure, the second adhesive layer includes a getter absorbing water and hydrogen. 
     According to some embodiments of the present disclosure, a bottom surface of the first metal layer is formed to be wider than a top surface of the second adhesive layer. 
     According to some embodiments of the present disclosure, the first metal layer and the second metal layer include aluminum (Al). 
     According to some embodiments of the present disclosure, a thickness of the second metal layer is set to be in the range of 2.0 mm to 2.5 mm. 
     According to some embodiments of the present disclosure, the second metal layer is thicker than the first metal layer. 
     According to some embodiments of the present disclosure, the second metal layer is formed on the resin layer to overlap the pad part. 
     According to some embodiments of the present disclosure, the display apparatus further includes a first adhesive member disposed between the printed circuit board and the second metal layer. 
     According to some embodiments of the present disclosure, the display apparatus further includes a first circuit cover covering the circuit film and the printed circuit board. 
     According to some embodiments of the present disclosure, the display apparatus further includes a second adhesive member disposed between the printed circuit board and the first circuit cover. 
     According to some embodiments of the present disclosure, one side of the first circuit cover is attached to a bottom surface of the substrate, and the another side of the first circuit cover is attached to a top surface of the second metal layer. 
     According to some embodiments of the present disclosure, the display apparatus further includes a coupling portion provided at an end of the first circuit cover and a fixing pin provided in a top surface of the second metal layer, wherein the first circuit cover is fixed to the top surface of the second metal layer by coupling of the coupling portion and the fixing pin. 
     According to some embodiments of the present disclosure, the coupling portion has a shape where a side surface thereof protrudes, and a groove is provided in an upper portion of the fixing pin. 
     According to some embodiments of the present disclosure, the display apparatus further includes a control printed circuit board provided on a top surface of the second metal layer, a plurality of control circuit films electrically connecting the control printed circuit board to the printed circuit board, and a second circuit cover covering the control printed circuit board and the plurality of control circuit films. 
     According to some embodiments of the present disclosure, a thickness of the first metal layer is set to be larger than or equal to 3.0 mm. 
     According to some embodiments of the present disclosure, the display apparatus further includes a circuit cover covering the pad part, the circuit film, and the printed circuit board, a first adhesive member disposed between the printed circuit board and the first metal layer, and a second adhesive member disposed between the printed circuit board and the first circuit cover. 
     According to some embodiments of the present disclosure, the display apparatus further includes a circuit cover covering the pad part, the circuit film, and the printed circuit board, wherein the substrate includes a top surface, including the pad part, and a light output surface opposite the top surface, and the circuit cover covers an edge of the light output surface of the substrate overlapping the pad part. 
     According to the present disclosure, a circuit film may be formed to contact the pad part and to extend toward the outside of the display apparatus along a side surface of the resin layer, a side surface of the first or second metal layer, and a top surface of the first or second metal layer, and thus, when the circuit film is bent inwardly, stress occurring in a surface of the circuit film and the damage to the circuit film caused by an end of the first or second metal layer may be reduced. Also, the stability of the circuit film may be secured, and thus, a thickness of the first metal layer or the second metal layer may increase, thereby enhancing the heat dissipation performance of the display apparatus. Furthermore, as a thickness of the first metal layer or the second metal layer increases, a back cover or an inner plate fundamentally included in the display apparatus may be replaced by or integrated into the first metal layer or the second metal layer, thereby providing a display apparatus including no back cover or inner plate. 
     Moreover, according to the present disclosure, a resin layer may be formed to cover a light emitting device and a first adhesive layer and may transfer, to a second metal layer, heat occurring in a light emitting device and heat discharged from a first metal layer, thereby enhancing the heat dissipation performance of a display apparatus. 
     Moreover, according to the present disclosure, the resin layer may be formed to cover a pad part, and thus, the pad part may not be exposed at the outside, thereby preventing a stripping defect and blocking an impact applied from the outside. Also, heat occurring in the pad part may be transferred to the second metal layer by the resin layer, and thus, heat occurring in the pad part may be discharged to the outside of the display apparatus. 
     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.