Patent Publication Number: US-11651727-B2

Title: Light emitting device with light emitting unit and driving circuit

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefits of the Chinese Patent Application Serial Number 202110011822.X, filed on Jan. 6, 2021, the subject matter of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     The present disclosure relates to a light emitting device. More specifically the present disclosure relates to a light emitting device in which light emitting units, pixel driving circuits and/or gate driving circuits may be disposed on different substrates. 
     2. Description of Related Art 
     In the conventional light emitting device, for example, a large-size public information display (PID) device, light emitting units, pixel driving circuits and gate driving circuits are disposed on the same substrate and then assembled with a circuit board. After packaging, cutting and splicing, the large-size public information display (PID) device can be obtained. 
     When cutting the substrates disposed with the light emitting units, the pixel driving circuits and the gate driving circuits, if other components are disposed at the cutting edge of the substrate, it may cause moisture to enter between layers, resulting in the deterioration of the color rendering of the display device. Alternatively, as the resolution of the display device increased, the gaps between the light emitting units are decreased, so the spaces for disposing the pixel driving circuits and the gate driving circuits are also decreased. Thus, the pixel driving circuits or the gate driving circuits at the edges of the substrates may be damaged during cutting. 
     Therefore, it is desirable to provide a light emitting device to solve the aforesaid problems. 
     SUMMARY 
     The present disclosure relates to a light emitting device, which comprises: a circuit board; a plurality of substrates comprising a first substrate and a second substrate, wherein the first substrate is disposed on the circuit board, and the second substrate is disposed on the circuit board and overlapped with the first substrate; a plurality of light emitting units disposed on the first substrate; a plurality of pixel driving circuits electrically connected to the plurality of light emitting units; and a plurality of gate driving circuits electrically connected to the plurality of pixel driving circuits, wherein at least a part of the plurality of pixel driving circuits or at least a part of the plurality of gate driving circuits are disposed on the second substrate. 
     Other novel features of the disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a schematic top view of a first substrate and light emitting units disposed thereon before cutting according to one embodiment of the present disclosure. 
         FIG.  1 B  is a schematic top view of a first substrate and light emitting units disposed thereon after cutting according to one embodiment of the present disclosure. 
         FIG.  2 A  is a schematic top view of a second substrate as well as pixel driving circuits and gate driving circuits disposed thereon before cutting according to one embodiment of the present disclosure. 
         FIG.  2 B  is a schematic top view of a second substrate as well as pixel driving circuits and gate driving circuits disposed thereon after cutting according to one embodiment of the present disclosure. 
         FIG.  3    is a schematic cross-sectional view of a light emitting device according to one embodiment of the present disclosure. 
         FIG.  4    is a schematic cross-sectional view of a light emitting device according to another embodiment of the present disclosure. 
         FIG.  5    is a schematic top view of a large-size public display device according to one embodiment of the present disclosure. 
         FIG.  6    to  FIG.  13    are schematic cross-sectional views according to different embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENT 
     Different embodiments of the present disclosure are provided in the following description. These embodiments are meant to explain the technical content of the present disclosure, but not meant to limit the scope of the present disclosure. A feature described in an embodiment may be applied to other embodiments by suitable modification, substitution, combination, or separation. 
     It should be noted that, in the present specification, when a component is described to have an element, it means that the component may have one or more of the elements, and it does not mean that the component has only one of the element, except otherwise specified. 
     Moreover, in the present specification, the ordinal numbers, such as “first” or “second”, are used to distinguish a plurality of elements having the same name, and it does not means that there is essentially a level, a rank, an executing order, or an manufacturing order among the elements, except otherwise specified. A “first” element and a “second” element may exist together in the same component, or alternatively, they may exist in different components, respectively. The existence of an element described by a greater ordinal number does not essentially means the existent of another element described by a smaller ordinal number. 
     In the present specification, except otherwise specified, the feature A “or” or “and/or” the feature B means the existence of the feature A, the existence of the feature B, or the existence of both the features A and B. The feature A “and” the feature B means the existence of both the features A and B. The term “comprise(s)”, “comprising”, “include(s)”, “including”, “have”, “has” and “having” means “comprise(s)/comprising but is/are/being not limited to”. 
     Moreover, in the present specification, the terms, such as “top”, “upper”, “bottom” or “middle”, as well as the terms, such as “on”, “above”, “over”, “under”, “below”, or “between”, are used to describe the relative positions among a plurality of elements, and the described relative positions may be interpreted to include their translation, rotation, or reflection. 
     Furthermore, the terms recited in the specification and the claims such as “above”, “over”, or “on” are intended not only directly contact with the other element, but also intended indirectly contact with the other element. Similarly, the terms recited in the specification and the claims such as “below”, or “under” are intended not only directly contact with the other element but also intended indirectly contact with the other element. 
     In addition, the term. “adjacent” in the specification and claims is used to describe mutual proximity, and does not necessarily mean mutual contact. 
     Moreover, in the present specification, a value may be interpreted to cover a range within ±20% of the value, and in particular, a range within ±10%, ±5%, ±3%, ±2%, ±1% or ±0.5% of the value, except otherwise specified. The value provided in the present specification is an approximate value, which means the meaning “about” is also included in the present disclosure without specifically specifying “about”. 
     In the present specification, except otherwise specified, the terms (including technical and scientific terms) used herein have the meanings generally known by a person skilled in the art. It should be noted that, except otherwise specified in the embodiments of the present disclosure, these terms (for example, the terms defined in the generally used dictionary) should have the meanings identical to those known in the art, the background of the present disclosure or the context of the present specification, and should not be read by an ideal or over-formal way. 
     In addition, the light emitting device disclosed in the present disclosure may include a display device, a touch display device, a curved display device or a free shape display device, but is not limited to this. The light emitting device can be a bendable or flexible light emitting device. The light emitting units of the light emitting device may include, for example, light emitting diode, quantum dot (QD), fluorescence, phosphor or other suitable display media, or a combination thereof, but is not limited to this. In the present disclosure, the light emitting diode may include, for example, OLED (organic light emitting diode), LED (light emitting diode), mini LED, micro LED, QD light emitting diode (for example, QLED, QDLED) or other suitable materials, or any combination thereof, but is not limited to this. The light emitting device may include, for example, a tiled light emitting device, but is not limited to this. It should be noted that the light emitting device can be any combination of the foregoing, but is not limited to this. In addition, the appearance of the light emitting device may be rectangular, circular, polygonal, a shape with curved edges, or other suitable shapes. The light emitting device may be provided with a driving system, a control system, a light source system, a shelf system or other peripheral systems to support a light emitting device or a tiled light emitting device. Hereinafter, a display device is used as an example to illustrate the light emitting device of the present disclosure, but the present disclosure is not limited thereto. 
       FIG.  1 A  and  FIG.  1 B  respectively are schematic top views of a first substrate and light emitting units disposed thereon before and after cutting according to one embodiment of the present disclosure. First, as shown in  FIG.  1 A , a first mother substrate  11  is provided, wherein the first mother substrate  11  comprises a predetermined region A, and the predetermined region A (as shown in the thick frame) comprises a plurality of pixel regions P (as shown in the thin frame), and each of the pixel regions P is correspondingly disposed with a light emitting unit  111 . Then, the first mother substrate  11  is cut along the cutting line C 1  to obtain the first substrate  11 ′ shown in  FIG.  1 B , wherein the first substrate  11 ′ comprises a plurality of pixel regions P, and each of the pixel regions P is correspondingly disposed with a light emitting unit  111 . Herein, the cutting line C 1  and the outermost light emitting units  111  may be separated by a distance G 1  in the X direction. The distance G 1  in the X direction between the cutting line C 1  and the outermost light emitting units  111  can ensure that the light emitting units  111  and/or the wirings under the light emitting units  111  should not be damage when cutting. In one embodiment of the present disclosure, the distance G 1  may satisfy the following equation (I):
 
0 μm≤ G 1≤( L 1 −L 2−( G 4)×2)/2   (I)
 
wherein L 1  is the width of the predetermined region A in the X direction, L 2  is the distance between the outermost edges of two outermost light emitting units  111  in the X direction, and G 4  is the distance that the cutting line C 1  has to be retracted from the predetermined region A. In another embodiment of the present disclosure, the distance G 1  may satisfy the following equation (I′):
 
0 μm&lt; G 1&lt;( L 1 −L 2−( G 4)×2)/2   (I′).
 
       FIG.  2 A  and  FIG.  2 B  respectively are schematic top views of a second substrate as well as pixel driving circuits and gate driving circuits disposed thereon before cutting and after cutting according to one embodiment of the present disclosure. First, as shown in  FIG.  2 A , a second mother substrate  12  is provided, wherein a plurality of scan lines S, a plurality of data lines D and a plurality of pixel driving circuits  121  are disposed on the second mother substrate  12 . Herein, the scan lines S intersect the data lines D, and the pixel driving circuits  121  respectively comprise a transistor. The scan line S is electrically connected to a gate electrode of the transistor, and the data line D is electrically connected to one end of the transistor. Herein, a plurality of gate driving circuits  122  are also disposed the second mother substrate  12  and electrically connected to the scan lines S, wherein the gate driving circuits  122  provide signals to the pixel driving circuits  121 . Furthermore, detection pads  125  are further disposed on the second mother substrate  12  and electrically connected to the data lines D, wherein the detection pads  125  can be connected to an optical inspection equipment (not shown in the figure) for circuit detection. Then, the second mother substrate  12  is cut along the cutting line C 2  to obtain the second substrate  12 ′ shown in  FIG.  2 B , wherein the second substrate  12 ′ comprises a plurality of pixel regions P′, and each of the pixel regions P′ is correspondingly disposed with a pixel driving circuit  121 . 
     In the present embodiment, the first substrate  11 ′ and the second substrate  12 ′ may respectively include a flexible substrate or a non-flexible substrates, and the materials thereof include, for example, glass, quartz, wafer, sapphire, polycarbonate (PC), polyimide (PI), polypropylene (PP), polyethylene terephthalate (PET), other suitable materials or a combination of the aforementioned materials; but the present disclosure is not limited thereto. The materials of the first substrate  11 ′ and the second substrate  12 ′ may be the same or different, depending upon the designs. In one embodiment of the present disclosure, the materials of the first substrate  11 ′ and the second substrate  12 ′ comprise PI, but the present disclosure is not limited thereto. 
       FIG.  3    is a schematic cross-sectional view of a light emitting device according to one embodiment of the present disclosure. After cutting the first mother substrate  11  and the second mother substrate  12  to obtain the first substrate  11 ′ and the second substrate  12 ′ (as shown in  FIG.  1 A  to  FIG.  2 B ), the first substrate  11 ′ and the second substrate  12 ′ are respectively disposed at two sides of a circuit board  13  to obtain the light emitting device of the present embodiment. 
     As shown in  FIG.  3   , the light emitting device of the present embodiment comprises: a circuit board  13 ; a plurality of substrates comprising a first substrate  11 ′ and a second substrate  12 ′, wherein the first substrate  11 ′ is disposed on the circuit board  13 , and the second substrate  12 ′ is disposed on the circuit board  13  and overlapped with the first substrate  11 ′; a plurality of light emitting units  111  disposed on the first substrate  11 ′; a plurality of pixel driving circuits  121  electrically connected to the plurality of light emitting units  111 ; and a plurality of gate driving circuits  122  electrically connected to the plurality of pixel driving circuits  121 , wherein at least a part of the plurality of pixel driving circuits  121  or at least a part of the plurality of gate driving circuits  122  are disposed on the second substrate  12 ′. 
     As shown in  FIG.  3   , in the light emitting device of the present embodiment, the circuit board  13  has a first surface  131  and a second surface  132  opposite to the first surface  131 , and the first substrate  11 ′ and the second substrate  12 ′ are respectively disposed on the first surface  131  and the second surface  132  of the circuit board  13 . In addition, the light emitting units  111  are disposed on the first substrate  11 ′, and the pixel driving circuits  121  and the gate driving circuits  122  are disposed on the second substrate  12 ′. 
     Herein, the second substrate  12 ′ is disposed on the second surface  132  of the circuit board  13 , and the pixel driving circuits  121  are electrically connected to the light emitting units  111  through the circuit board  13 . More specifically, as shown in  FIG.  2 B  and  FIG.  3   , one end of the pixel driving circuit  121  is electrically connected to the data line D, and the other end of the pixel driving circuit  121  is electrically connected to the light emitting unit  111  through the circuit board  13 . Thus, the purpose of electrically connecting the pixel driving circuits  121  and the light emitting units  111  through the circuit board  13  can be achieved. 
     As shown in  FIG.  3   , since the units (for example, the light emitting units  111 ) on the first substrate  11 ′ is disposed on a surface of the first substrate  11 ′ opposite to another surface of the first substrate  11 ′ facing the circuit board  13 , the units (for example, the light emitting units  111 ) on the first substrate  11 ′ may be electrically connected to the circuit board  13  through bridging lines  113  penetrating the first substrate  11 ′. Since the units (for example, pixel driving circuits  121  or gate driving circuits  122 ) on the second substrate  12 ′ are disposed on a surface of the second substrate  12 ′ opposite to another surface of the second substrate  12 ′ facing to the circuit board  13 , the units (for example, pixel driving circuits  121  or gate driving circuits  122 ) on the second substrate  12 ′ may also be electrically connected to the circuit board  13  through the bridging lines  123  penetrating the second substrate  12 ′. More specifically, the light emitting device of the present embodiment may further comprise a bridging line  123  penetrating the second substrate  12 ′, and at least a part of the pixel driving circuits  121  may be electrically connected to the light emitting units  111  through the circuit board  13  and the bridging line  123 . Similarly, the light emitting device of the present embodiment may further comprise another bridging line  113  penetrating the first substrate  11 ′, and each of the light emitting units  111  may be electrically connected to the pixel driving circuits  121  through the bridging line  113  and the circuit board  13 . 
     In the conventional light emitting device that all the light emitting units, the pixel driving circuits and the gate driving circuits are disposed on the same substrate, if the substrate disposed with all the aforesaid units is laminated on the circuit board, followed by packaging and cutting, it is not easy to meet the current requirements for accuracy and the required cutting tolerance is large because the substrate and the circuit board are cut at the same time. In addition, because all the aforesaid units are disposed on the same substrate, the wiring range on the substrate is relatively large, and the wiring at the edge of the substrate may be damaged easily during cutting. Or, other components may be disposed at the cutting edge of the substrate, and it may cause moisture to enter between layers, resulting in the deterioration of the light emitting device. 
     Thus, in the light emitting device of the present embodiment, the light emitting units  111  and at least a part of the pixel driving circuits  121  and/or at least a part of the gate driving circuits  122  are disposed on different substrates, and then laminated on the circuit board  13  after cutting the substrates. Thus, the wiring range of one single substrate can be effective reduced, so the cutting tolerance can be increased, the problem of damaging the wiring on the substrate can be prevented, and/or the problem of moisture entrance caused by the destruction of layers can be avoided. 
     In another embodiment of the present disclosure, as shown in  FIG.  4   , the units (for example, pixel driving circuits  121  or gate driving circuits  122 ) on the second substrate  12 ′ are disposed on a surface of the second substrate  12 ′ facing the circuit board  13 . Thus, the units (for example, pixel driving circuits  121  or gate driving circuits  122 ) on the second substrate  12 ′ may be electrically connected to the circuit board  13  through the contact pads  124 , and then electrically connected to the light emitting units  111  electrically connected to the circuit board  13 . 
     In  FIG.  3    and  FIG.  4   , after the first substrate  11 ′ and the second substrate  12 ′ are respectively disposed on the first surface  131  and the second surface  132  of the circuit board  13 , the circuit board  13  is cut along the cutting line C 3 . Finally, as shown in  FIG.  5   , a plurality of the light emitting devices shown in  FIG.  3    or  FIG.  4    are spliced after cutting to obtain the tiled light emitting device of the present embodiment. The tiled light emitting device may be used in a large-size public display device, but the present disclosure is not limited to this. 
     As shown in  FIG.  5   , in the tiled light emitting device of the present embodiment, the gap G 2  between two adjacent light emitting units  111  of two adjacent first substrates  11 ′ is substantially equal to the gap G 3  between two adjacent light emitting units  111  on the same first substrate  11 ′, to avoid the problem of the inconsistence in display images. In order to make the gap G 2  substantially equal to the gap G 3  and to avoid the risk of cutting the first substrate  11 ′ when cutting the circuit board  13  (as shown in  FIG.  3    or  FIG.  4   ), as shown in  FIG.  1 A , the cutting line C 1  has to be retracted by a distance G 4  from the predetermined region A when cutting the first mother substrate  11 , and the cutting line C 1  may be separated from the outermost light emitting unit  111  by a distance G 1 . 
     In addition, as shown in  FIG.  3    or  FIG.  4   , when cutting the circuit board  13 , the position of the cutting line C 3  may refer the position of the predetermined region A. More specifically, in the direction (X direction) perpendicular the normal direction of the substrate (Z direction), the position of the cutting line C 3  may be separated from an edge  11   a  of the first substrate  11 ′ by a distance G 4 ′, and this distance G 4 ′ may be substantially equal to the distance G 4 . Thus, after splicing the light emitting devices, as shown in  FIG.  5   , the purpose of the gap G 2  substantially equal to the gap G 3  can be achieved. 
     As shown in  FIG.  1 A  and  FIG.  5   , when the cutting line C 1  is retracted from the predetermined region A, the distance G 5  between two adjacent first substrates  11 ′ may satisfy the tolerance required for splicing, and this tolerance may compensate for the errors caused by cutting machines, cutting steps or other processes. Herein, the distance G 5  between two adjacent first substrates  11 ′ may be twice the distance G 4 ′ (as shown in  FIG.  3   ). In the present embodiment, the distance G 5  between two adjacent first substrates  11 ′ may satisfy the following equation (II):
 
0 μm≤ G 5≤( L 1 −L 2)/2   (II)
 
wherein, L 1  is the width of the predetermined region A in the X direction, and L 2  is the distance between the outermost edges of two outermost light emitting units  111  in the X direction. In another embodiment, the distance G 5  may satisfy the following equation (II′):
 
0 μm&lt; G 5≤( L 1 −L 2)/2   (II′).
 
     In the conventional light emitting device that all the light emitting units, the pixel driving circuits and the gate driving circuits are disposed on the same substrate, if the substrate disposed with all the aforesaid units is laminated on the circuit board, followed by packaging and cutting, since the wirings near to the side of the substrate occupy a certain space, the splicing tolerance between two adjacent substrates is quite small to maintain the same pixel pitch after splicing. In other words, the alignment has to be very accurate when splicing, so that the problem of the inconsistence in display images will not be occurred. However, in the light emitting device of the present embodiment, the light emitting units  111  as well as at least a part of the pixel driving circuits  121  and/or at least a part of the gate driving circuits  122  are disposed on different substrates, so the distance G 5  between two adjacent first substrates  11 ′ can be increased to increase the tolerance required for splicing, and the problem of the inconsistence of display images caused by the inaccurate alignment of two substrates will not be easily occurred. 
     In  FIG.  1 A  to  FIG.  5   , the distances G 1 , G 4 , G 4 ′, G 5 , the gaps G 2 , G 3 , the width L 1  and the distance L 2  are exemplified in one direction (X direction) perpendicular to the normal direction of the substrate (Z direction). The distances, the gaps and the widths in another direction (Y direction) perpendicular to the normal direction of the substrate (Z direction) may also be designed by the same manner described above, which are not repeated again. 
       FIG.  6    to  FIG.  13    are schematic cross-sectional views according to different embodiments of the present disclosure. In the embodiments shown in  FIG.  6    to  FIG.  13   , for the convenience of explanation, the bridging lines  113 ,  123  shown in  FIG.  3    or the contact pads  124  shown in  FIG.  4    are omitted. In addition, in  FIG.  6    to  FIG.  11    and  FIG.  13   , the second substrate  12 ′ and/or the third substrate  14 ′ may be electrically connected to the circuit board  13  by the manner shown in  FIG.  3    or  FIG.  4   . 
     The embodiment shown in  FIG.  6    is similar to the embodiment shown in  FIG.  3   . One difference is that, in the embodiment shown in  FIG.  6   , at least part of the gate driving circuits  122  are disposed on the first substrate  11 ′. 
     The embodiment shown in  FIG.  7    is similar to the embodiment shown in  FIG.  6   , and the differences between the embodiments shown in  FIG.  6    and  FIG.  7    are as follows. In the embodiment shown in  FIG.  7   , another part of the pixel driving circuits  121  are disposed on the first substrate  11 ′, and the data lines (not shown in the figure) electrically connected to the pixel driving circuits  121  disposed on first substrate  11 ′ are also disposed on the first substrate  11 ′. In addition, the pixel driving circuits  121  on the first substrate  11 ′ are electrically connected to the light emitting units  111  through contact pads  112 . In the present embodiment, the pixel driving circuits  121  electrically connected to the light emitting units  111  closest to the edges  11   a  of the first substrate  11 ′ are still disposed on the second substrate  12 ′, and the pixel driving circuits  121  disposed on the first substrate  11 ′ are the pixel driving circuits  121  electrically connected to the light emitting units  111  which is not closest to the edges  11   a  of the first substrate  11 ′. It is because when the pixel driving circuits  121  electrically connected to the light emitting units  111  which are disposed closest to the edge  11   a  of the first substrate  11 ′ are still disposed on the second substrate  12 ′, the retracted distance for cutting the first mother substrate can be increased, and the distance G 4 ′ between the cutting line C 3  and the edges  11   a  of the first substrate  11 ′ can be increased. Thus, the tolerance required for splicing two adjacent first substrates  11 ′ (for example, the distance G 5  shown in  FIG.  5   ) can be increased. 
     The embodiment shown in  FIG.  8    is similar to the embodiment shown in  FIG.  3   , and the differences between the embodiments shown in  FIG.  8    and  FIG.  3    are as follows. In the embodiment shown in  FIG.  8   , all the pixel driving circuits  121  are disposed on the first substrate  11 ′, and the data lines (not shown in the figure) electrically connected to the pixel driving circuits  121  disposed on the first substrate  11 ′ are also disposed on the first substrate  11 ′. In addition, the pixel driving circuits  121  disposed on the first substrate  11 ′ are electrically connected to the light emitting units  111  through contact pads  112 . Thus, in the present embodiment, the second substrate  12 ′ is not disposed with the pixel driving circuits  121  and only disposed with the gate driving circuits  122 . 
     The embodiment shown in  FIG.  9    is similar to the embodiment shown in  FIG.  3   , and the differences between the embodiments shown in  FIG.  9    and  FIG.  3    are as follows. In the embodiment shown in  FIG.  9   , at least a part of the pixel driving circuits  121  are disposed on the first substrate  11 ′, and the data lines (not shown in the figure) electrically connected to the pixel driving circuits  121  disposed on first substrate  11 ′ are also disposed on the first substrate  11 ′. In addition, the pixel driving circuits  121  on the first substrate  11 ′ are electrically connected to the light emitting units  111  through contact pads  112 . In the present embodiment, the pixel driving circuits  121  disposed on the first substrate  11 ′ are the pixel driving circuits  121  electrically connected to the light emitting units  111  which is not closest to the edges  11   a  of the first substrate  11 ′. The reason has been described above and is not repeated again. Furthermore, in the present embodiment, the gate driving circuits  122  are adjacent to the edges  12   a  of the second substrate  12 ′, but the present disclosure is not limited thereto. In another embodiment of the present disclosure, a part of the pixel driving circuits  121  may be adjacent to the edges  12   a  of the second substrate  12 ′. In further another embodiment of the present disclosure, a part of the gate driving circuits  122  may be adjacent to the edges  12   a  of the second substrate  12 ′, and a part of the pixel driving circuits  121  may be adjacent to the edges  12   a  of the second substrate  12 . 
     The embodiment shown in  FIG.  10    is similar to the embodiment shown in  FIG.  9   , and the differences between the embodiments shown in  FIG.  10    and  FIG.  9    are as follows. In the embodiment shown in  FIG.  10   , the plurality of substrates further comprise a third substrate  14 ′, and another part of the gate driving circuits  122  are disposed on the third substrate  14 ′. More specifically, in the present embodiment, the second substrate  12 ′ is disposed with a part of the pixel driving circuits  121  and a part of the gate driving circuits  122 , and the third substrate  14 ′ is also disposed with a part of the pixel driving circuits  121  and a part of the gate driving circuits  122 . 
     The embodiment shown in  FIG.  11    is similar to the embodiment shown in  FIG.  10   . One difference is that, in the embodiment show in  FIG.  11   , the second substrate  12 ′ is disposed with a part of the pixel driving circuits  121 , and the third substrate  14 ′ is disposed with a part of the gate driving circuits  122 . 
     Except for the embodiments shown in  FIG.  10    and  FIG.  11   , the present disclosure further provides other embodiments similar to the embodiments shown in  FIG.  10    and  FIG.  11   . In one embodiment of the present disclosure, the pixel driving circuits  121  may be disposed on the first substrate  11 ′ and the gate driving circuits  122  may be disposed on one or more third substrate  14 ′. In another embodiment of the present disclosure, the pixel driving circuits  121  may be disposed on one or more second substrate  12 ′, and the gate driving circuits  122  may be disposed on one or more third substrate  14 ′. In another embodiment of the present disclosure, the light emitting units  111  and the gate driving circuits  122  may be disposed on the first substrate  11 ′, and the pixel driving circuits  121  may be disposed on one or more second substrate  12 ′. In further another embodiment of the present embodiment, the light emitting units  111 , a part of the pixel driving circuits  121  and a part of the gate driving circuits  122  may be disposed on the first substrate  11 ′, and the remaining pixel driving circuits  121  and the remaining gate driving circuits  122  may disposed on one or more second substrate  12 ′ or on one or more third substrate  14 ′. 
     The embodiment shown in  FIG.  12    is similar to the embodiment shown in  FIG.  3   . One difference is that, in the embodiment shown in  FIG.  12   , the second substrate  12 ′ is disposed on the first surface  131  of the circuit board  13 , and disposed between the first substrate  11 ′ and the circuit board  13 . In another embodiment, a part of the pixel driving circuits  121  may be disposed on the first substrate  11 ′. In another embodiment of the present disclosure, a part of the gate driving circuits  122  may be disposed on the first substrate  11 ′. In further another embodiment of the present disclosure, a part of the pixel driving circuits  121  and a part of the gate driving circuits  122  may be disposed on the first substrate  11 ′. 
     The embodiment shown in  FIG.  13    is similar to the embodiment shown in  FIG.  12   . One difference is that, in the embodiment shown in  FIG.  13   , the plurality of substrates further comprise a third substrate  14 ′, and a part of the gate driving circuits  122  are disposed on the third substrate  14 ′. In another embodiment of the present disclosure, a part of the pixel driving circuits  121  may be disposed on the first substrate  11 ′. In further another embodiment of the present disclosure, the plurality of substrates may further comprise one or more third substrate  14 ′, and the gate driving circuits  122  may be disposed on one or more third substrate  14 ′. 
     In the embodiments shown in  FIG.  3    and  FIG.  4   , the pixel driving circuits  121  and the gate driving circuits  122  are disposed on the second surface  132  of the circuit board  13 . Thus, the pixel driving circuits  121  and the gate driving circuits  122  may be electrically connected to the light emitting units  111  through the wirings inside the circuit board  13 . 
     In the embodiments shown in  FIG.  6    to  FIG.  13   , at least a part of the pixel driving circuits  121  and/or at least a part of the gate driving circuits  122  are disposed on the first surface  131  of the circuit board  13 . Thus, at least a part of the pixel driving circuits  121  and/or at least a part of the gate driving circuits  122  disposed on the first surface  131  of the circuit board  13  may be electrically connected to the light emitting units  111  without using the wirings inside the circuit board  13 , so the design of the wirings inside the circuit board  13  may be simplified. 
     In the aforesaid embodiments of the present disclosure, the light emitting devices having light emitting units arranged in a 6×6 array are exemplified, but the number of the light emitting units arranged in the light emitting device of the present disclosure is not limited thereto and may be adjusted according to the design or need. In addition, in the aforesaid embodiments of the present disclosure, the tiled light emitting device formed by the light emitting devices arranged in a 2×4 array are exemplified, but the number of the light emitting devices arranged in the tiled light emitting device of the present disclosure is also not limited thereto and may be adjusted according to the design or need. 
     In the present disclosure, the features in different embodiments of the present disclosure can be mixed to form another embodiment without departing from the spirit and scope of the disclosure as hereinafter claimed. 
     Although the present disclosure has been explained in relation to its embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the disclosure as hereinafter claimed. 
     In addition, the aforesaid embodiments are examples for convenience of description, and the claimed scope of the present disclosure should be subjected to the claims, rather than being limited to the aforesaid embodiments.