Patent Publication Number: US-2023155100-A1

Title: Display device

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a bypass continuation of International Application No. PCT/KR2021/008744, filed on Jul. 8, 2021, in the Korean Intellectual Property Receiving Office, which is based on and claims priority to Korean Patent Application No. 10-2020-0097125, filed on Aug. 4, 2020, in the Korean Intellectual Property Office, the disclosures of which are incorporated by reference herein in their entireties. 
    
    
     BACKGROUND 
     1. Field 
     The disclosure relates to a display device displaying an image by combining modules in which a self-luminous inorganic light emitting diodes is mounted on a substrate. 
     2. Description of Related Art 
     A display device visually displays data information, such as text and figures, and images. 
     In general, a liquid crystal display (LCD) panel and an organic light-emitting diode (OLED) panel are mainly used in the display device. However, the LCD panel has a slow response time, and consumes high power. In addition, the LCD panel does not emit light by itself Above all, because the LCD panel requires a backlight, it is difficult to make the LCD panel slim. An OLED panel is advantageous to make the display device thin because the OLED panel includes self-luminous elements and does not require the backlight. However, OLED panels are vulnerable to a burn-in phenomenon in which specific image remains, such as an afterimage of the LCD panel. 
     Therefore, a micro-LED panel is being researched as a new panel that may compensate for the shortcomings mentioned above. As for the micro-LED panel, inorganic light emitting diodes are mounted on a substrate and the inorganic light emitting diodes are used as pixels. 
     The micro-LED panel is one of the flat display panels and is composed of inorganic light emitting diodes of  100  micrometers or less. 
     The LED panel is a self-luminous element without an OLED burn-in, and has excellent luminance, resolution, power consumption, and durability. 
     The micro-LED panel has superior contrast, response time, and high energy efficiency compared to the LCD panel, which requires a backlight. Although the OLED and the micro-LED (which is an organic LED), both have good energy efficiency, the micro-LED is superior in brightness, luminous efficiency, and lifespan. 
     In addition, by arranging micro-LEDs on a circuit board in pixel units, it is possible to manufacture displays as modules in units of substrates, and also with various resolutions and screen sizes according to the customer&#39;s order. 
     SUMMARY 
     Provided is a display device which may be capable of preventing a reduction in display performance of a part of a screen, which is displayed by a plurality of display modules, caused by heat generated by the display device. 
     Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments. 
     According to an aspect of the disclosure, a display device includes a plurality of display modules, each of the plurality of display modules including: a substrate having a mounting surface and a rear surface opposite the mounting surface; a plurality of inorganic light emitting diodes provided on the mounting surface of the substrate; and a frame supporting the plurality of display modules arranged in a matrix, the frame including: a first frame layer contacting the plurality of display modules and including a material having material properties similar to material properties of the substrate; a second frame layer provided behind the first frame layer, and including a metal material; and a third frame layer provided between the first frame layer and the second frame layer and bonding the first frame layer and the second frame layer. 
     The substrate and the first frame layer may include the same material. 
     A ductility of the third frame layer may be greater than a ductility of the first frame layer and a ductility of the second frame layer. 
     A coefficient of thermal expansion of the first frame layer may be less than a coefficient of thermal expansion of the second frame layer. 
     The third frame layer may include a first adhesive layer bonded to the first frame layer, a second adhesive layer bonded to the second frame layer, and a high ductility layer provided between the first adhesive layer and the second adhesive layer, and varying in thickness in a direction that the mounting surface faces. 
     A thickness of the first frame layer in a direction that the mounting surface faces may be less than a thickness of the second frame layer in the direction that the mounting surface faces. 
     Each of the plurality of display modules may include a metal plate configured to dissipate heat generated from the substrate and facing the rear surface of the substrate and an adhesive member bonding the plurality of display modules to the first frame layer. 
     Each of the plurality of display modules may include an adhesive layer provided between the rear surface of the substrate and the metal plate, the adhesive layer bonding the rear surface of the substrate and the metal plate, and a ductility of the adhesive layer may be greater than a ductility of the substrate and the metal plate. 
     The adhesive member may be provided on the metal plate such that the metal plate is bonded to the first frame layer. 
     The adhesive member may be provided on the rear surface of the substrate such that the substrate is bonded to the first frame layer. 
     According to an aspect of the disclosure, a display device includes a plurality of display modules, each of the plurality of display modules including: a substrate including a glass material and having a mounting surface; and a plurality of inorganic light emitting diodes mounted on the mounting surface of the substrate; and a frame supporting the plurality of display modules arranged in a matrix , the frame including a glass layer to which the plurality of display modules is bonded. 
     The frame may include a support layer provided behind the glass layer and supporting the glass layer, and an adhesive layer provided between the glass layer and the support layer and bonding the glass layer and the support layer. 
     A coefficient of thermal expansion of the glass layer may be less than a coefficient of thermal expansion of the support layer. 
     The support layer may include a metal material. 
     A ductility of the adhesive layer may be greater than a ductility of the glass layer and a ductility of the support layer. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The above and other aspects, features, and advantages of certain embodiments of the present disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
         FIG.  1    is a diagram illustrating a display device according to an embodiment of the present disclosure; 
         FIG.  2    is a diagram illustrating main configurations of a display device according to an embodiment of the present disclosure; 
         FIG.  3    is a cross-sectional view of a portion of a display module according to an embodiment of the present disclosure; 
         FIG.  4    is a diagram of the display module of a display device according to an embodiment of the present disclosure; 
         FIG.  5    is a diagram of a frame of a display device according to an embodiment of the present disclosure; 
         FIG.  6    is a cross-sectional view of a part of the frame of a display device according to an embodiment of the present disclosure; and 
         FIG.  7    is a cross-sectional view of a portion of a display device according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments described herein are merely examples. Accordingly, the described embodiments do not represent all the technical ideas of the disclosure. Therefore, at the time of filing of the disclosure, it should be understood that various equivalents or modifications that can be substituted for the embodiment are also included in the scope of the disclosure. 
     A singular expression used in the description may include a plural expression unless the context clearly indicates otherwise. The shapes and sizes of elements in the drawings may be exaggerated for a clear description. 
     In the present specification, terms such as ‘comprise’ or ‘have’ are intended to indicate the presence of feature(s), number(s), step(s), operation(s), component(s), part(s), or combinations thereof described in the specification. Accordingly, it should be understood that the existence or addition of one or more other feature(s), number(s), step(s), operation(s), component(s), part(s), or combination(s) thereof is not precluded in advance. 
     Also, in the present specification, the meaning of ‘identical’ may indicate that objects having properties similar or contrasting to each other are in a similar state within a certain degree. Also, a word such as ‘identical’ and ‘same’ may mean ‘substantially the same level of identity’. The meaning of ‘substantially the same level’ may indicate the degree to which the difference is very small and usually falls within the error range that occurs during manufacturing process. 
     Hereinafter, a preferred embodiment according to the disclosure will be described in detail with reference to the accompanying drawings. 
       FIG.  1    is a diagram illustrating a display device according to an embodiment of the present disclosure.  FIG.  2    is a diagram illustrating main configurations of a display device according to an embodiment of the present disclosure.  FIG.  3    is a cross-sectional view of a portion of a display module according to an embodiment of the present disclosure.  FIG.  4    is a diagram of the display module of a display device according to an embodiment of the present disclosure. 
     Some components of a display device  1  including a plurality of inorganic light emitting diodes  50  shown in the drawings are actually very small elements. That is, because the size unit is micrometers, for convenience of explanation, the scales of components such as the plurality of inorganic light emitting diodes  50  and a black matrix  58  are exaggerated. 
     The display device  1  is an electronic device for displaying information, material, and data as text, figure, graph, and image to a viewer. The display device  1  may be a television (TV), a personal computer (PC), a mobile device, digital signage, etc.. 
     According to an embodiment of the present disclosure, as shown in  FIGS.  1  and  2   , the display device  1  may include a display panel  20  for displaying an image, power supply circuit for supplying power to the display panel  20 , and a main board  25  for controlling the overall operation of the display panel  20 . In addition, the display device  1  may include a frame  100  supporting the display panel  20  and a rear cover  10  that covers a rear surface of the frame  100 . 
     The display panel  20  may include a plurality of display modules  30 A to  30 P and a driving board for driving each of the display modules  30 A to  30 P. In addition, the display panel  20  may include a timing control board that generates a timing signal required to control each of the display modules  30 A to  30 P. 
     The rear cover  10  may support the display panel  20 . The rear cover  10  may be combined with a stand or a wall mount to install the display device  1  on a floor or a wall. 
     The plurality of display modules  30 A to  30 P may be arranged vertically and horizontally to be adjacent to each other. The plurality of display modules  30 A to  30 P may be arranged in a matrix of M*N. In this embodiment,  16  display modules are configured as examples, and are arranged in a 4*4 matrix form. However, there is no limitation in the numbers and arrangement of the plurality of display modules. 
     The plurality of display modules  30 A to  30 P may be fixed to the frame  100 . The plurality of display modules  30 A to  30 P may be installed in the frame  100  by various known methods such as magnetic force using a magnet, a mechanical fitting method, or adhesion. The rear cover  10  may be coupled to the rear of the frame  100 , and the rear cover  10  may form a rear exterior of the display device  1 . 
     The rear cover  10  may be made of a metal material. Accordingly, heat generated by the plurality of display modules  30 A to  30 P may be easily conducted to the rear cover  10  to increase the heat dissipation efficiency of the display device  1 . 
     As will be described later, the frame  100  and the plurality of display modules  30 A to  30 P may be bonded to each other by a second adhesive layer  90  disposed behind the plurality of display modules  30 A to  30 P. 
     The rear side of the plurality of display modules  30 A to  30 P may be supported on the frame  100  by the second adhesive layer  90 . 
     As described above, the display device  1  according to an embodiment of the present disclosure may implement a large screen by tiling the plurality of display modules  30 A to  30 P. 
     Each of the display modules may be applied to a separate independent display device. That is, each of the display modules  30 A to  30 P may be applied to a small display device such as a wearable device, a portable device, and a handheld device. The display modules  30 A to  30 P may be arranged in a matrix form as the embodiment of the disclosure to be applied to a display device such as a monitor for a personal computer, a high-resolution TV, a signage, and an electronic display. 
     Each of the plurality of display modules  30 A to  30 P may have the same configuration. Accordingly, the description of the display module described below may be equally applied to all other display modules. 
     Hereinafter, a first display module  30 A among the plurality of display modules  30 A to  30 P will be described as an example. The first display module  30 A may be formed in a quadrangle. The first display module  30 A may be provided in a rectangle or a square. 
     Accordingly, the first display module  30 A may include edges  31 ,  32 ,  33 , and  34  formed at all sides with respect to the first direction X, which is the front. 
     As shown in  FIG.  3   , each of the plurality of display modules  30 A to  30 P may include a substrate  40  and a plurality of inorganic light emitting diodes  50  mounted on the substrate  40 . The plurality of inorganic light emitting diodes  50  may be mounted on a mounting surface  41  of the substrate  40  facing the first direction X. In  FIG.  3   , a thickness of the substrate  40  in the first direction X is exaggerated for convenience of description. 
     The substrate  40  may be formed in a quadrangle. As described above, each of the plurality of display modules  30 A to  30 P may be provided in a quadrangle, and the substrate  40  may be formed in a quadrangle to correspond thereto. 
     The substrate  40  may be provided in a rectangle or a square. 
     Accordingly, the substrate  40  may include four edges corresponding to the edges  31 ,  32 ,  33 , and  34  of the first display module  30 A based on the first direction X, which is the front. 
     The substrate  40  may include a base substrate  42 , the mounting surface  41  forming one surface of the base substrate  42 , a rear surface  43  forming the other surface of the base substrate  42  and disposed opposite to the mounting surface  41 , and a side surface  45  connecting the mounting surface  41  and the rear surface  43 . 
     The substrate  40  may include a thin film transistor (TFT) layer  44  formed on the base substrate  42  to drive the inorganic light emitting diodes  50 . The base substrate  42  may be a glass substrate. The substrate  40  may be a Chip on Glass (COG) type substrate. First and second pad electrodes  44   a  and  44   b  provided to electrically connect the inorganic light emitting diodes  50  to the TFT layer  44  may be formed on the substrate  40 . 
     The TFT constituting the TFT layer  44  is not limited to a specific structure or type, and may be configured in various embodiments. That is, the TFT of the TFT layer  44  according to an embodiment of the present disclosure may be a Low Temperature Poly Silicon (LTPS) TFT, oxide TFT, Si (poly silicon or a-silicon) TFT, organic TFT, graphene TFT, etc. 
     Also, in case that the base substrate  42  of the substrate  40  is formed of a silicon wafer, the TFT layer  44  may be replaced with a Complementary Metal-Oxide Semiconductor (CMOS) type, n-type MOS field effect transistor (FET) (MOSFET), or p-type MOSFET transistor. 
     The plurality of inorganic light emitting diodes  50  may be formed of inorganic materials, and may be elements having sizes of several μm to several tens of μm in width, length, and height, respectively. The micro inorganic light emitting diodes may have a length of 100 μm or less on a short side among width, length, and height. The inorganic light emitting diodes  50  may be picked up from a wafer formed of a sapphire or silicon material and transferred directly onto the substrate  40 . The plurality of inorganic light emitting diodes  50  may be picked up and transported by an electrostatic method using an electrostatic head or a stamp method using an elastic polymer material such as polydimethylsiloxane (PDMS) or silicone as a head. 
     The plurality of inorganic light emitting diodes  50  may have a light emitting structure including an n-type semiconductor  58   a , an active layer  58   c , a p-type semiconductor  58   b , a first contact electrode  57   a , and a second contact electrode  57   b.    
     One of the first contact electrode  57   a  and the second contact electrode  57   b  may be electrically connected to the n-type semiconductor  58   a  and the other may be electrically connected to the p-type semiconductor  58   b.    
     The first contact electrode  57   a  and the second contact electrode  57   b  may be horizontally disposed and may be a flip chip type disposed in a direction opposite to the light emission direction. 
     In case that the inorganic light emitting diodes  50  is mounted on the mounting surface  41 , the inorganic light emitting diodes  50  may include a light emitting surface  54  disposed toward the first direction X, a side surface  55 , and a bottom surface  56  disposed on the opposite side of the light emitting surface  54 . The first contact electrode  57   a  and the second contact electrode  57   b  may be formed on the bottom surface  56 . 
     The contact electrodes  57   a  and  57   b  of the inorganic light emitting diodes  50  are disposed on the opposite side of the light emitting surface  54  and thus may be disposed on the opposite side of the direction in which light is irradiated. 
     The contact electrodes  57   a  and  57   b  are disposed to face the mounting surface  41 , and are electrically connected to the TFT layer  44 . The light emitting surface  54  for irradiating light is disposed in a direction opposite to the direction in which the contact electrodes  57   a  and  57   b  are disposed. 
     Accordingly, when the light generated in the active layer  58   c  is irradiated in the first direction X through the light emitting surface  54 , the light may be irradiated toward the first direction X without interference of the first contact electrode  57   a  or the second contact electrode  57   b.    
     The first direction X may be defined as a direction to which the light emitting surface  54  emits light. 
     The first contact electrode  57   a  and the second contact electrode  57   b  may be electrically connected to the first pad electrode  44   a  and the second pad electrode  44   b  formed on the mounting surface  41  of the substrate  40 , respectively. 
     As will be described later, the inorganic light emitting diodes  50  may be directly connected to the pad electrodes  44   a  and  44   b  through an anisotropic conductive layer  47  or a bonding material such as solder. 
     The anisotropic conductive layer  47  that mediates electrical bonding between the contact electrodes  57   a  and  57   b  and the pad electrodes  44   a  and  44   b  may be formed on the substrate  40 . The anisotropic conductive layer  47  may have a structure in which an anisotropic conductive adhesive is attached on a protective film, and conductive balls  47   a  may be dispersed in an adhesive resin. The conductive ball  47   a  may be a conductive sphere surrounded by a thin insulating film, and may electrically connect the conductors to each other in case that the insulating film is broken by pressure. 
     The anisotropic conductive layer  47  may include an anisotropic conductive film (ACF) in the form of a film and an anisotropic conductive paste (ACP) in the form of a paste. 
     Therefore, in a state in which the plurality of inorganic light emitting diodes  50  is mounted on the substrate  40 , when pressure is applied to the anisotropic conductive layer  47 , the insulating film of the conductive ball  47   a  is broken, and thus the contact electrodes  57   a  and  57   b  of the inorganic light emitting diodes  50  may be electrically connected with the pad electrodes  44   a  and  44   b  of the substrate  40 . 
     However, the plurality of inorganic light emitting diodes  50  may be mounted on the substrate  40  through solder instead of the anisotropic conductive layer  47 . After the inorganic light emitting diodes  50  is aligned on the substrate  40 , the inorganic light emitting diodes  50  may be bonded to the substrate  40  through a reflow process. 
     The plurality of inorganic light emitting diodes  50  may include a red light emitting diodes  51 , a green light emitting diodes  52 , and a blue light emitting diodes  53 . A series of the red light emitting diodes  51 , the green light emitting diodes  52 , and the blue light emitting diodes  53 , which is as one unit, may be mounted on the mounting surface  41  of the substrate  40 . The red light emitting diodes  51 , the green light emitting diodes  52 , and the blue light emitting diodes  53  may form one pixel. In this case, each of the red light emitting diodes  51 , the green light emitting diodes  52 , and the blue light emitting diodes  53  may serve as a sub pixel. 
     The light emitting diodes  51 ,  52 , and  53  may be arranged in a line at a predetermined interval as the embodiment of the disclosure, or may be arranged in a shape other than the disclosure, such as a triangular shape. 
     The substrate  40  may include a light absorption layer  44   c  to absorb external light to improve contrast. The light absorption layer  44   c  may be formed on the mounting surface  41  of the substrate  40 . The light absorption layer  44   c  may be formed between the TFT layer  44  and the anisotropic conductive layer  47 . 
     The plurality of display modules  30 A to  30 P may further include a black matrix  48  formed between the plurality of inorganic light emitting diodes  50 . 
     The black matrix  48  may serve to supplement the light absorption layer  44   c  formed entirely on the mounting surface  41  of the substrate  40 . That is, the black matrix  48  may absorb external light to allow the substrate  40  to appear black, thereby improving the contrast of the screen. 
     In example embodiments, the black matrix  48  has a black color. 
     In the present embodiment, it has been described that the black matrix  48  is formed between pixels composed of the light emitting diodes  51 ,  52 , and  53 . Alternatively, the black matrix  48  may be more specifically formed to define the light emitting diodes  51 ,  52 , and  53  which are sub-pixels. 
     The black matrix  48  may be in the form of a grid in which horizontal and vertical straight lines intersect is formed, so as to be arranged between pixels. 
     The black matrix  48  may be formed by applying a light-absorbing ink on the anisotropic conductive layer  47  and then curing the light-absorbing ink by an ink-jet process. In addition, the black matrix  48  may be formed by coating the anisotropic conductive layer  46  with the light absorption film. 
     In addition, the black matrix  48  may be formed in a space where the plurality of inorganic light emitting diodes  50  is not mounted on the anisotropic conductive layer  47  formed on the mounting surface  41 . 
     The plurality of display modules  30 A to  30 P may each include a front cover  49  disposed in the first direction X to cover the mounting surface  41  of the plurality of display modules  30 A to  30 P. 
     The front cover  49  may be provided in plurality so as to be respectively disposed on the plurality of display modules  30 A to  30 P. 
     The front cover  49  may be in the form of a film. The front cover  49  may include an adhesive layer provided to bond the front cover  49  to the mounting surface  41  of the substrate  40 . 
     The film of the front cover  49  may be provided as a functional film having optical performance. 
     The front cover  49  may cover the substrate  40  to protect the substrate  40  from 
     external force. 
     The adhesive layer of the front cover  49  may be provided to have a height greater than or equal to a predetermined height in the first direction X in which the mounting surface  41  or the light emitting surface  54  faces. The height of the adhesive layer is used to fill a gap that may be formed between the front cover  49  and the plurality of inorganic light emitting diodes  50  when the front cover  49  is disposed on the substrate  40 . 
     Each of the display modules  30 A to  30 P may include a metal plate  60  provided on the rear surface  43  of the substrate  40  to dissipate heat generated from the substrate  40 . 
     In addition, the plurality of display modules  30 A to  30 P may include a first adhesive layer  70  disposed between the rear surface  43  and the metal plate  60  to bond the metal plate  60  and the rear surface  43  of the substrate  40 . 
     Because pixel driving wirings for driving the plurality of inorganic light emitting diodes  50  are formed on a top wiring layer, the plurality of inorganic light emitting diodes  50  may be electrically connected to the top wiring layer formed on the mounting surface  41 . 
     The top wiring layer may be formed under the anisotropic conductive layer  47 . The top wiring layer may be electrically connected to a side wiring formed on the side surface  45  of the substrate  40 . The side wiring may be provided in the form of a thin film. 
     The top wiring layer may be connected to the side wiring by a top connection pad formed on the edge of the substrate  40 . 
     The side wiring may extend along the side surface  45  of the substrate  40  and may be connected to a rear wiring layer  43   b  formed on the rear surface  43 . 
     An insulating layer  43   c  covering the rear wiring layer  43   b  may be formed on the rear wiring layer  43   b  in a direction in which the rear surface of the substrate  40  faces. 
     That is, the plurality of inorganic light emitting diodes  50  may be sequentially electrically connected to the top wiring layer, the side wiring, and the rear wiring layer  43   b.    
     Also, as shown in  FIG.  4   , the display module  30 A may include a driving circuit board  80  for electrically controlling the plurality of inorganic light emitting diodes  50  mounted on the mounting surface  41 . The driving circuit board  80  may be a printed circuit board. The driving circuit board  80  may be disposed on the rear surface  43  of the substrate  40  in the first direction X. Although described in detail later, the driving circuit board  80  may be disposed on the metal plate  60  bonded to the rear surface  43  of the substrate  40 . 
     The display module  30 A may include a flexible film  81  connecting the driving circuit board  80  and the rear wiring layer  43   b  such that the driving circuit board  80  is electrically connected to the plurality of inorganic light emitting diodes  50 . 
     One end of the flexible film  81  may be connected to a rear connection pad  43   d  disposed on the rear surface  43  of the substrate  40  and electrically connected to the plurality of inorganic light emitting diodes  50 . 
     The rear connection pad  43   d  may be electrically connected to the rear wiring layer  43   b  . Accordingly, the rear connection pad  43   d  may electrically connect the rear wiring layer  43   b  and the flexible film  81 . 
     The flexible film  81  may transmit power and electrical signals from the driving circuit board  80  to the plurality of inorganic light emitting diodes  50  as the flexible film  81  is electrically connected to the rear connection pad  43   d.    
     The flexible film  81  may be a flexible flat cable (FFC) or a chip on film (COF). 
     The flexible film  81  may include a first flexible film  81   a  and a second flexible film  81   b  respectively disposed at different positions with respect to the first direction X. 
     The first and second flexible films  81   a  and  81   b  are not limited thereto and may be disposed in left and right directions or in at least two directions in the up, down, left, and right directions, respectively, with respect to the first direction X. 
     The display module  30 A may include a plurality of second flexible films  81   b . However, the disclosure is not limited thereto. The number of the second flexible film  81   b  may be one, and the display module  30 a may include a plurality of first flexible films  81   a.    
     The first flexible film  81   a  may transmit a data signal from the driving circuit board  80  to the substrate  40 . The first flexible film  81   a  may be formed of COF. 
     The second flexible film  81   b  may transmit power from the driving circuit board  80  to the substrate  40 . The second flexible film  81   b  may be formed of FFC. 
     However, the disclosure is not limited thereto. The first and second flexible films  81   a  and  81   b  may be formed in opposite types to each other. 
     The driving circuit board  80  may be electrically connected to the main board  25  (refer to  FIG.  2   ). The main board  25  may be disposed at the rear of the frame  100 , and the main board  25  may be connected to the driving circuit board  80  through a cable at the rear of the frame  100 . 
     As described above, the metal plate  60  may contact the substrate  40 . The metal plate  60  and the substrate  40  may be bonded by a first adhesive layer  70  disposed between the rear surface  43  of the substrate  40  and the metal plate  60 . 
     The metal plate  60  may be made of a metal material having high thermal conductivity. For example, the material of the metal plate  60  may be an aluminum. 
     Heat generated from the plurality of inorganic light emitting diodes  50  and the TFT layer  44  mounted on the substrate  40  may be transferred to the metal plate  60  through the rear surface  43  of the substrate  40  and the first adhesive layer  70 . 
     Accordingly, heat generated from the substrate  40  may be easily transferred to the metal plate  60 , and the temperature of the substrate  40  may be prevented from rising above a certain level. 
     The plurality of display modules  30 A to  30 P may be arranged to form a matrix of M*N, respectively. Each of the display modules  30 A to  30 P may be individually disposed. Because each of the display modules  30 A to  30 P individually includes the metal plate  60 , the display modules  30 A to  30 P may maintain a certain level of dissipation performance regardless of the arrangement. 
     The plurality of display modules  30 A to  30 P may form screens of various sizes of the display device  1  in a matrix form of various M * N. Accordingly, because each of the display modules  30 A to  30 P includes an independent metal plate  60  and each of the display modules  30 A to  30 P individually dissipate heat, the overall heat dissipation performance of the display device  1  may be improved in comparison with dissipating heat through a single metal plate provided for heat dissipation. 
     When a single metal plate is disposed inside the display device  1 , a portion of the metal plate may not be disposed at a position where some display modules are disposed and the metal plate may be disposed at a position where the display module is not disposed. Accordingly, heat dissipation efficiency of the display device  1  may be reduced. 
     That is, by the metal plate  60  disposed on each of the display modules  30 A to  30 P, each of the display modules  30 A to  30 P dissipates heat by the respective metal plate  60  regardless of position. Accordingly, heat dissipation performance of the display device  1  as a whole may be improved. 
     The metal plate  60  may be provided in a rectangular shape substantially corresponding to the shape of the substrate  40 . 
     An area of the substrate  40  may be at least equal to or larger than an area of the metal plate  60 . While the substrate  40  and the metal plate  60  are disposed side by side in the first direction X, the four edges of the substrate  40  may be disposed to correspond to the four edges of the metal plate  60  with respect to the center of the metal plate  60 . Alternatively, the four edges of the substrate  40  may be disposed outside the four edges of the metal plate  60  with respect to the center of the metal plate  60 . 
     The four edges of the substrate  40  may be disposed outside the four edges of the metal plate  60 . That is, the area of the substrate  40  may be larger than the area of the metal plate  60 . 
     As will be described later, when heat is generated in each of the display modules  30 A to  30 P, the substrate  40  and the metal plate  60  may be thermally expanded. Because the coefficient of thermal expansion of the metal plate  60  is higher than the coefficient of thermal expansion of the substrate  40 , the metal plate  60  may expand more in volume than the substrate  40 . 
     In case that the four edges of the substrate  40  correspond to the four edges of the metal plate  60  or are disposed inside, the edges of the metal plate  60  may protrude outside the edges of the substrate  40 . 
     Accordingly, gaps between the display modules  30 A to  30 P arranged in a matrix form may be irregularly formed by thermal expansion of the metal plate  60 . Finally, the perception of the seam may be increased and thus the uniformity of the screen of the display panel  20  may be reduced. 
     However, in case that the four edges of the substrate  40  are disposed outside the four edges of the metal plate  60 , even if the substrate  40  and the metal plate  60  are thermally expanded, the four edges of the metal plate  60  do not protrude outward the four edges of the substrate  40 . As a result, the gap formed between the display modules  30 A to  30 P may be kept constant. 
     Additionally, in order to maintain a constant gap formed between the respective display modules  30 A to  30 P, the frame  100  supporting each of the display modules  30 A to  30 P may include a first frame layer  110  having material properties similar to those of the substrate  40 . This will be described later in detail. 
     According to an embodiment of the present disclosure, the area of the substrate  40  and the area of the metal plate  60  may be substantially similar. Accordingly, the heat generated by the substrate  40  may be uniformly dissipated without being isolated in some regions. 
     The metal plate  60  may be bonded to the rear surface  43  of the substrate  40  by the first adhesive layer  70 . 
     The first adhesive layer  70  may have a size corresponding to size of the metal plate  60 . That is, the area of the first adhesive layer  70  may correspond to the area of the metal plate  60 . The metal plate  60  may be provided in a substantially rectangular shape, and the first adhesive layer  70  may be provided in a rectangular shape to correspond thereto. 
     Based on the center of the metal plate  60  and the first adhesive layer  70 , the edge of the rectangular metal plate  60  and the edge of the first adhesive layer  70  may be formed to correspond to each other. 
     As a result, the metal plate  60  and the first adhesive layer  70  may be easily manufactured as a single bonding structure, and thus the manufacturing efficiency of the display device  1  may be increased. 
     In detail, before cutting one large metal plate into the metal plate  60  of a unit size, the first adhesive layer  70  may be bonded to the metal plate. Because the first adhesive layer  70  and the metal plate  60  are simultaneously cut to a unit size, an effect of reducing the process may occur. 
     Heat generated from the substrate  40  may be transferred to the metal plate  60  through the first adhesive layer  70 . Therefore, the first adhesive layer  70  may serve to bond the metal plate  60  to the substrate  40 , and simultaneously transfer heat generated from the substrate  40  to the metal plate  60 . 
     Therefore, the first adhesive layer  70  may be formed of a material having high heat dissipation performance. 
     Basically, the first adhesive layer  70  may include an adhesive material to bond the substrate  40  and the metal plate  60  together. 
     Additionally, the first adhesive layer  70  may include a material having higher heat dissipation performance than a material having general adhesive properties. Accordingly, between the substrate  40  and the metal plate  60 , the first adhesive layer  70  may efficiently transfer heat to each component. 
     In addition, the adhesive material of the first adhesive layer  70  may be formed of a material having higher heat dissipation performance than an adhesive material constituting a general adhesive. 
     The material with high heat dissipation performance means a material that effectively transfers heat with high thermal conductivity, high heat transferability, and low specific heat. 
     For example, the first adhesive layer  70  may include a graphite material. However, the disclosure is not limited thereto, and the first adhesive layer  70  may be generally made of a material having high heat dissipation performance. 
     Ductility of the first adhesive layer  70  may be greater than ductility of the substrate  40  and the metal plate  60 . Accordingly, the first adhesive layer  70  may be made of a material having high ductility while having adhesive properties and heat dissipation properties. The first adhesive layer  70  may be formed of an inorganic double-sided tape. The first adhesive layer  70  formed of the inorganic tape may be formed as a single layer in which a member, which supports one surface bonded to the substrate  40  and the other surface bonded to the metal plate  60 , is not present between the one surface and the other surface. 
     Because the first adhesive layer  70  does not contain a configuration that prevents heat conduction, the first adhesive layer  70  may have high heat dissipation performance. However, the first adhesive layer  70  is not limited to the inorganic double-sided tape, and may be provided with a heat dissipation tape having better heat dissipation performance than a general double-sided tape. 
     As described above, the substrate  40  may be made of a glass material, and the metal plate  60  may be made of a metal material. Accordingly, because the material properties of each component are different, the extent to which the material is deformed by the same heat may be different. That is, when heat is generated in the substrate  40 , the substrate  40  and the metal plate  60  may expand thermally to different degrees by heat, respectively. Accordingly, the display module  30 A may be damaged. 
     In a state in which the substrate  40  and the metal plate  60  are fixed to each other, because the degree of the expansion of the substrate  40  and the metal plate  60  at the same temperature is different, stress may be generated in each component as the substrate  40  and the metal plate  60  expand to different sizes. 
     Because the coefficient of thermal expansion of each material is different, the degree to which the material is physically deformed by heat may be different. In particular, because the thermal expansion coefficient of the metal material is generally larger than the thermal expansion coefficient of glass, when the same heat is transferred to the substrate  40  and the metal plate  60 , the metal plate  60  may expand and deform more than the substrate  40 . 
     Conversely, even when the substrate  40  and the metal plate  60  are cooled, the metal plate  60  may shrink and deform more than the substrate  40 . 
     Because the substrate  40  and the metal plate  60  are bonded to each other by the first adhesive layer  70  and the metal plate  60  is deformed more than the substrate  40 , an external force by the metal plate  60  may be transmitted to the substrate  40 . 
     Conversely, an external force by the substrate  40  may be transmitted to the metal plate  60 , but the substrate  40  may be damaged because the rigidity of the glass substrate  40  is smaller than the rigidity of the metal plate  60  made of metal. 
     The first adhesive layer  70  may be provided between the substrate  40  and the metal plate  60  to absorb external forces which is transmitted to each other while the substrate  40  and the metal plate  60  expand in different sizes. 
     Accordingly, an external force is transmitted to the substrate  40  and the metal plate  60 , and in particular, it is possible to prevent the substrate  40  from being damaged. 
     The first adhesive layer  70  may be made of a material having high ductility to absorb the external force transmitted from the substrate  40  and the metal plate  60 . In other words, the ductility of the first adhesive layer  70  may be greater than the ductility of the substrate  40  and the metal plate  60 . 
     Accordingly, when the external force generated from the size change of the substrate  40  and the metal plate  60  is transmitted to the first adhesive layer  70 , the first adhesive layer  70  itself is deformed, and thus the external force may be prevented from being transferred to the different configuration. 
     The first adhesive layer  70  may have a predetermined thickness in the first direction X. When heat is transferred to the metal plate  60  to thermally expand or contract, the metal plate  60  may expand or contract in a direction orthogonal to the first direction X as well as the first direction X. Accordingly, an external force may be transmitted to the substrate  40 . 
     Even when the metal plate  60  expands or contracts in a direction perpendicular to the first direction X, the thickness of the first adhesive layer  70  may vary, thereby preventing the external force from being transmitted to the substrate  40 . Additionally, the thermal expansion coefficient of the first adhesive layer  70  may be different from the thermal expansion coefficient of the substrate  40  and the metal plate  60 . 
     The coefficient of thermal expansion of the first adhesive layer  70  may be greater than that of the substrate  40  and less than the coefficient of thermal expansion of the metal plate  60 . 
     Accordingly, the first adhesive layer  70  may not deform in the same way as either the substrate  40  or the metal plate  60  at the same temperature, and the first adhesive layer  70  may buffer the deformation of each configuration between the substrate  40  and the metal plate  60 . 
     Therefore, the first adhesive layer  70  is disposed between the substrate  40  and the metal plate  60  and deformed to easily absorb the external force generated depending on the difference in thermal expansion rate between the substrate  40  and the metal plate  60 . 
     A thickness t 1  of the substrate  40  may be at least twice as thick as a thickness t 2  of the metal plate  60  (See  FIG.  3   ). 
     This is because the rigidity of the metal plate  60  is higher than that of the substrate  40  and thus it is in order to reduce an external force transmitted to the substrate  40  caused by a temporary distortion in the display module  30 A due to the thermal expansion. 
     Because the substrate  40  is formed of a glass material and the metal plate  60  is formed of a metal material, the flatness of the glass plate of the substrate  40  may be provided more uniformly than the flatness of the metal plate. 
     Therefore, the substrate  40  and the metal plate  60  may be slightly different in flatness. Because the substrate  40  and the metal plate  60  are contact and coupled as described above, stress may be generated in each configuration depending on the degree of flatness. 
     Because the rigidity of the substrate  40  is low, there is a possibility that the substrate  40  is damaged. To prevent this, the thickness t 1  of the substrate  40  may be at least twice as thick as the thickness t 2  of the metal plate  60  to reduce the external force transmitted to the substrate  40 . 
     However, this is an example thickness value. The thickness t 2  of the metal plate  60  may be thicker than ½ of the thickness t 1  of the substrate  40 . 
     The first adhesive layer  70  may have a third thickness t 3 . The third thickness t 3  may be greater than or equal to a minimum length that allows the first adhesive layer  70  to be maintained at a state in which an additional external force is not applied to the substrate  40  when the first adhesive layer  70  is deformed due to the thermal expansion of the metal plate  60  and the substrate  40 . 
     The display module  30 A may include a second adhesive layer  90  provided to couple the frame  100  and the display module  30 A. 
     The second adhesive layer  90  may be disposed on the rear surface of the metal plate  60  to allow the metal plate  60  to be bonded to the frame  100 . 
     As described above, the metal plate  60  may be formed to have a size corresponding to the size of the substrate  40  to cover the entire rear surface  43  of the substrate  40 . The second adhesive layer  90  may be disposed on the rear surface of the metal plate  60 . 
     However, the disclosure is not limited thereto. The second adhesive layer  90  may be disposed on the rear surface  43  of the substrate  40 . In this case, the substrate  40  may be directly bonded to the frame  100  through the second adhesive layer  90 . 
     The metal plate  60  may be provided to cover only a portion of the rear surface  43  of the substrate  40 . The second adhesive layer  90  may be bonded to the region of the rear surface  43  of the substrate  40  that is not covered by the metal plate  60 . 
     Accordingly, the display modules  30 A to  30 P may be directly bonded to the front surface of the first frame layer  110  by the second adhesive layer  90 . The first frame layer  110  may form the front surface of the frame  100 . The substrate  40  of the display modules  30 A to  30 P may be formed of a glass material. The display modules  30 A to  30 P may be bonded to the first frame layer  110  formed of a glass material through the second adhesive layer  90 . Therefore, it is possible to minimize a change in the gap between the display modules  30 A to  30 P that may be caused by thermal expansion. This will be described later in detail. 
     Hereinafter the frame  100  according to an embodiment of the present disclosure will be described in detail. 
       FIG.  5    is a diagram of a frame of a display device according to an embodiment of the present disclosure.  FIG.  6    is a cross-sectional view of a part of the frame of a display device according to an embodiment of the present disclosure.  FIG.  7    is a cross-sectional view of a portion of a display device according to an embodiment of the present disclosure. 
     The screen of the display panel  20  may be configured by the plurality of display modules  30 A to  30 P as described above. In this case, a seam by the gap formed between the plurality of display modules  30 A to  30 P may be a factor that may affect the uniformity of the screen. 
     Accordingly, in order to minimize the perception of the seam of the display panel  20 , the plurality of display modules  30 A to  30 P may be disposed on the frame  100  to form a predetermined gap. This is to prevent a phenomenon in which the perception of the seam is increased due to some gaps when the gaps formed by the plurality of display modules  30 A to  30 P are not constant. 
     In addition, the front cover  49  may be provided to absorb light irradiated or reflected toward the gap between the display modules  30 A to  30 P, so as to minimize the perception of the seam of the display panel  20 . 
     In the case of a conventional display device, a frame supporting the display panel is made of a metal material. A plurality of display modules may be tiled on a metal frame. 
     The substrate forming the plurality of display modules  30 A to  30 P may be thermally expanded by heat generated from the display panel while the display device is driven. As described above, because the plurality of display modules  30 A to  30 P is supported by the frame made of metal, gaps between the plurality of display modules  30 A to  30 P are irregularly formed due to thermal expansion of the substrate and the frame, and the perception of the seam of the screen may be increased. 
     That is, substrates of the plurality of display modules  30 A to  30 P are all made of a glass material and thus each substrate may thermally expand at a constant value. Some gaps between the plurality of display modules  30 A to  30 P may be irregularly formed due to thermal expansion of the metal frame supporting each substrate. This is because the material properties of the metal material and the material properties of the glass material are different. 
     The material properties may vary depending on the coefficient of thermal expansion, specific heat, thermal conductivity, and the like. In particular, the degree of thermal expansion between the substrate and the frame may be different due to the difference between the thermal expansion coefficient of the metal and the thermal expansion coefficient of glass. 
     As the thermal expansion parameter of the substrate of the plurality of display modules  30 A to  30 P interacts with the thermal expansion parameter of the frame, a gap between the plurality of display modules  30 A to  30 P may be irregularly formed. 
     As the plurality of display modules  30 A to  30 P are arrayed on a metal frame, gaps between the plurality of display modules  30 A to  30 P are irregularly formed. To prevent this phenomenon, the frame  100  may include the first frame layer  110  to which the plurality of display modules  30 A to  30 P is bonded, and having material properties similar to those of the substrate  40  of the plurality of display modules  30 A to  30 P. 
     The first frame layer  110  may be disposed in front of the frame  100  in the first direction X to which the mounting surface  41  faces. 
     The plurality of display modules  30 A to  30 P may be attached to the first frame layer  110  of the frame  100 . 
     The meaning of being formed with a material having material properties similar to material properties of the above-described substrate  40  may include meaning that those of the material are similar to the thermal expansion coefficient, specific heat, and thermal conductivity of the substrate  40 . In particular, according to an embodiment of the present disclosure, it could be understood that the coefficient of thermal expansion of the substrate  40  corresponds to the coefficient of thermal expansion of the first frame layer  110 . 
     In detail, when the same heat is transferred to the substrate  40  and the first frame layer  110  in the second direction Y or the third direction Z orthogonal to the first direction X, the substrate  40  and the first frame layer  110  may be expanded to a length corresponding to each other. 
     The first frame layer  110  may be made of a material having a thermal expansion coefficient similar to that of the substrate  40 . The first frame layer  110  may be formed of a material having the same thermal expansion coefficient as that of the substrate  40 . 
     The substrate  40  and the first frame layer  110  may be formed of a glass material. Accordingly, the thermal expansion coefficients of the substrate  40  and the first frame layer  110  may be the same. 
     Because the first frame layer  110  is formed of a glass material, the first frame layer  110  may be referred to as a glass layer  110 , but hereinafter, it will be referred to as the first frame layer  110 . 
     Accordingly, when heat is generated while the display device  1  is driven, the substrate  40  of the plurality of display modules  30 A to  30 P and the first frame layer  110  may thermally expand to the same value. 
     Because the first frame layer  110 , to which the plurality of display modules  30 A to  30 P is bonded, thermally expands to the same value as that of the substrate  40 , the gap formed between the plurality of display modules  30 A to  30 P may be maintained constantly. 
     Accordingly, because the gap formed between the plurality of display modules  30 A to  30 P is maintained at the same distance, the seam may be maintained at the certain extent and thus the display panel  20  may always have the same screen integrity or uniformity. 
     Even when heat generated by driving the display device  1  is supplied to the substrate  40  of the plurality of display modules  30 A to  30 P, the gap between the plurality of display modules  30 A to  30 P may be constant. As a result, it is possible to prevent a phenomenon in which the integrity of the screen is deteriorated caused by the enlarged seam. 
     As shown in  FIG.  5   , the frame  100  may include the first frame layer  110  contacting the plurality of display modules  30 A to  30 P and having the same coefficient of thermal expansion as that of the substrate  40 . The first frame layer  110  may be made of a glass material. The frame  100  may include a second frame layer  130  disposed behind the first frame layer  110  in a direction to which the mounting surface  41  faces. The second frame layer  130  may support the first frame layer  110 . The frame  100  may include a third frame layer disposed between the first frame layer  110  and the second frame layer  130  in a direction to which the mounting surface  41  faces. The third frame layer may be provided to bond the first frame layer  110  and the second frame layer  130  to each other. 
     The third frame layer  120  may be referred to as an adhesive layer. However, in order to prevent mixing of the names of the above-described first adhesive layer  70  and the second adhesive layer  90 , it may be referred to as a ‘third adhesive layer’. However, hereinafter it will be referred to as the third frame layer  120 . 
     Also, the second frame layer  130  may be referred to as a support layer  130 . However, hereinafter it will be referred to as the second frame layer  130 . 
     The frame  100  may be configured to support the display panel  20  and may be provided to have a rigidity greater than or equal to a predetermined level. In this case, when the frame  100  is formed using only the first frame layer  110  described above, it may be difficult to secure a certain level of rigidity. Therefore, the frame  100  may additionally include the second frame layer  130  supporting the first frame layer  110 . 
     The second frame layer  130  may include a metal material to secure rigidity. 
     The second frame layer  130  may be formed only of a metal material, but may be formed by a combination of a metal plate formed of a metal material and a foam member bonded to the metal plate. 
     In order to secure the rigidity of the frame  100 , the thickness of the first frame layer  110  with respect to the direction to which the mounting surface faces may be less than the thickness of the second frame layer  130 . The first frame layer  110  may be configured to maintain a gap between the plurality of display modules  30 A to  30 P. However, because the second frame layer  130  supports the plurality of display modules  30 A to  30 P, it is required that the second frame layer  130  has high rigidity. 
     Because the second frame is a configuration that supplements the first frame layer  110  formed of a glass material having low rigidity, the frame  100  may stably support the display panel  20  by the second frame layer  130 . 
     In order to secure a certain level of rigidity or more, the second frame layer  130  may be formed to be thicker than the first frame layer  110  in the direction to which the mounting surface  41  faces. 
     Each of the layers  110 ,  120 , and  130  may be sequentially disposed in the order of the first frame layer  110 , the third frame layer  120 , and the second frame layer  130  based on the direction to which the mounting surface  41  faces. 
     The coefficient of thermal expansion of the first frame layer  110  may be less than that of the second frame layer  130 . This is because the first frame layer  110  is formed of a material similar to that of the substrate  40 , and the second frame layer  130  is formed of the metal material to support the first frame layer  110  as described above. 
     In general, because the substrate of the display module is formed of a glass material, the first frame layer  110  may be formed of a glass material, and the second frame layer  130  includes a metal material to secure rigidity. Accordingly, the first frame layer  110  may be provided to have a lower coefficient of thermal expansion than that of the second frame layer  130 . 
     The first frame layer  110  and the second frame layer  130  are bonded to each other by the third frame layer  120 . Accordingly, when the second frame layer  130  is deformed more than the first frame layer  110 , an external force may be transmitted to the first frame layer  110 . When heat is supplied to the frame  100 , the second frame layer  130  including the metal material may expand more than the first frame layer  110  formed of the glass material. 
     Alternatively, an external force by the first frame layer  110  may be transmitted also to the second frame layer  130 . Because the rigidity of the first frame layer  110  made of glass is smaller than that of the second frame layer  130  made of metal, the first frame layer  110  may be damaged. 
     In order to prevent the first frame layer  110  from being damaged, the third frame layer  120  may be provided to absorb external forces. The third frame layer  120  may be disposed between the first frame layer  110  and the second frame layer  130  to absorb external forces which is transmitted to each other while the substrate  40  and the metal plate  60  expand in different sizes. 
     Accordingly, example embodiments may prevent the external force from being transmitted to the first frame layer  110  and the second frame layer  130  and particularly, example embodiments may prevent the first frame layer  110  from being damaged. 
     The third frame layer  120  may be made of a material having high ductility. In other words, the ductility of the third frame layer  120  may be greater than the ductility of the first frame layer  110  and the second frame layer  130 . 
     It is in order to prevent the external force, which is generated by the change in the size of the first frame layer  110  and the second frame layer  130  due to the thermal expansion, from being transmitted to the first frame layer  110  and the second frame layer  130 . 
     That is, the external force generated by the first frame layer  110  and the second frame layer  130  may be applied to each component through the third frame layer  120  disposed between the first frame layer  110  and the second frame layer  130 . 
     As described above, the ductility of the third frame layer  120  may be greater than the ductility of the first frame layer  110  and the second frame layer  130 . Due to the high ductility of the third frame layer  120 , the external force transmitted to the third frame layer  120  is used to deform the third frame layer  120  itself As a result, because the transmitted external force is consumed for deformation of the third frame layer  120 , the external force is not transmitted to the first frame layer  110  and the second frame layer  130 . 
     The third frame layer  120  may have a predetermined thickness t 6  in the first direction X (refer to  FIG.  7   ). When the second frame layer  130  is thermally expanded or contracted by the heat, the second frame layer  130  may transmit an external force to the metal plate  60  and the substrate  40 . The direction in which the external force acts may be a direction orthogonal to the first direction X. 
     Even if the second frame layer  130  expands or contracts in a direction orthogonal to the first direction X, the thickness t 6  of the third frame layer  120  is changed in the first direction X, and transmission of external force to the first frame layer  110  may be prevented because the third frame layer  120  has a predetermined thickness t 6  in the first direction X. 
     In addition, even if a portion of the second frame layer  130  expands in the first direction X due to distortion occurring as the second frame layer  130  thermally expands, because the third frame layer  120  has the predetermined thickness t 6  in the first direction X, the thickness t 6  of the third frame layer  120  may be changed in the first direction X to offset the distortion of the second frame layer  130  to prevent the external force from being transmitted to the first frame layer  110 . 
     Additionally, the thermal expansion coefficient of the third frame layer  120  may be different from the thermal expansion coefficient of the first frame layer  110  and the second frame layer  130 . 
     Accordingly, as the third frame layer  120  deforms itself, the third frame layer  120  may easily absorb an external force generated according to a difference in thermal expansion coefficient. The third frame layer  120  may be disposed between the first frame layer  110  and the second frame layer  130  to easily absorb an external force generated according to a difference in thermal expansion coefficient. 
     As shown in  FIG.  6   , the third frame layer  120  may include a first adhesive layer  121  bonded to the first frame layer  110 , a second adhesive layer  122  bonded to the second frame layer  130 , and a high ductility layer  123  disposed between the first adhesive layer  121  and the second adhesive layer  122 . The high ductility layer  123  may be provided to allow the thickness of the high ductility layer  123  to vary in the direction of the mounting surface  41 . 
     The first and second adhesive layers  121  and  122  may be configured to bond the first frame layer  110  and the second frame layer  130  to each other, and may be made of the same material. 
     The high ductility layer  123  may be made of a polyurethane material. 
     The high ductility layer  123  may be provided as a foam layer including a plurality of air bubbles  124 . The high ductility layer  123  may be provided to have high ductility by the plurality of bubbles  124  therein. 
     The high ductility layer  123  may be easily deformed in the direction to which the mounting surface  41  faces or the direction perpendicular to the direction to which the mounting surface  41 , by the plurality of air bubbles  124  therein. A void space may be formed in the high ductility layer  123  by the plurality of air bubbles  124 . The high ductility layer  123  may be easily deformed by the void space. 
     When the first frame layer  110  and the second frame layer  130  thermally expand to different degrees by thermal expansion, and external forces of different degrees are transmitted to the third frame layer  120 , the third frame layer  120  may not transmit an external force to each other. Because of the high ductility layer  123 , the third frame layer  120  may consume the transmitted external force in its deformation. 
     Even if the first frame layer  110  and the second frame layer  130  have different thermal expansion coefficients, and even if heat is supplied to the frame  100  by the third frame layer  120 , it is possible to prevent the first frame layer  110  having a lower rigidity than the second frame layer  130  from being damaged. 
     The third frame layer  120  may be provided as a double-sided adhesive tape having the plurality of layers  121 ,  122 , and  123  described above. 
     As shown in  FIG.  7   , the second frame layer  130  may be formed of a metal layer  131  formed of a metal material and a foamed resin layer  132  formed of a foamed resin. 
     Also, the second frame layer  130  may be formed of a single metal plate. However, as long as a certain level of rigidity is secured by the metal layer  131  and the foamed resin layer  132  having a predetermined thickness, the second frame layer  130  may include the metal layer  131  and the foamed resin layer  132 . 
     In case that the second frame layer  130  includes the foamed resin layer  132 , the amount of metal used to form the second frame layer  130  may be reduced. Accordingly, the weight of the second frame layer  130  may be reduced, and the production cost of the second frame layer  130  may be reduced. 
     As described above, the thickness tl of the base substrate  42  of the substrate  40  may be approximately twice as thick as the thickness t 2  of the metal plate  60 . 
     The third thickness t 3  of the first adhesive layer  70  may be greater than or equal to a minimum length that allows the first adhesive layer  70  to be maintained at a state in which an additional external force is not applied to the substrate  40  when the first adhesive layer  70  is deformed due to the thermal expansion of the metal plate  60  and the substrate  40 . 
     The thickness t 4  of the second adhesive layer  90  may be greater than or equal to a minimum thickness that maintains adhesion between the display module  30 A and the frame  100 . 
     In order to secure rigidity, the thickness t 7  of the second frame layer  130  may be greater than the thickness t 5  of the first frame layer  110  and the thickness t 6  of the third frame layer  120 . 
     Alternatively, in case that a larger number of display modules than the plurality of display modules  30 A to  30 P are supported by the frame  100 , the thickness t 7  of the second frame layer  130  and the thickness t 5  of the first frame layer  110  may be increased. 
     In addition, the area of the second frame layer  130  and the first frame layer  110  may be formed to be larger than the sum of the areas of the plurality of display modules  30 A to  30 P. 
     When a larger number of display modules than the plurality of display modules  30 A to  30 P are supported by the frame  100 , the weight of the display panel  20  increases, and thus additional rigidity of the frame  100  may be required. 
     That is, as the size of the screen of the display panel  20  increases, the thickness t 7  of the second frame layer  130  and the thickness t 5  of the first frame layer  110  may be increased. 
     The thickness t 6  of the third frame layer  120  may be greater than or equal to a minimum length that allows the third frame layer  120  to be maintained at a state in which an additional external force is not applied to the first frame layer  110  when the third frame layer  120  is deformed due to the thermal expansion of the first frame layer  110  and the second frame layer  130 . 
     The thickness t 6  of the third frame layer  120  may be variously formed depending on the materials of the first adhesive layer  121 , the second adhesive layer  122 , and the high ductility layer  123 . That is, in the case of the disclosure, the thickness t 6  of the third frame layer  120  may be approximately equal to or less than the thickness t 5  of the first frame layer  110 . However, the disclosure is not limited thereto, and the thickness t 6  of the third frame layer  120  may be  1 / 2  or less than the thickness t 5  of the first frame layer  110  depending on the materials of the first adhesive layer  121 , the second adhesive layer  122 , and the high ductility layer  123 . 
     A display device may include a frame formed of the same material as a material of a substrate of a plurality of display modules and the frame may include a portion to which the substrate of the plurality of display modules is bonded. When the substrate is thermally expanded by heat generated in the display device, the portion of the frame to which the plurality of display modules is bonded may be thermally expanded to the same level as the substrate. Accordingly, because a gap between the plurality of display modules is maintained at a certain level, it is possible to prevent an increase in a seam that may occur between the plurality of display module. 
     While the present disclosure has been particularly described with reference to exemplary embodiments, it should be understood by those of skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the present disclosure.