Patent Publication Number: US-10776065-B2

Title: Display device comprising two display panels

Description:
This application is a continuation of copending U.S. application Ser. No. 14/876,238, filed on Oct. 6, 2015 which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     One embodiment of the present invention relates to a display device. 
     Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. In addition, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Specifically, examples of the technical field of one embodiment of the present invention disclosed in this specification include a semiconductor device, a display device, a light-emitting device, a lighting device, a power storage device, an input device, a method for driving any of them, and a method for manufacturing any of them. 
     BACKGROUND ART 
     In recent years, larger display devices have been required. For example, a television device for home use (also referred to as a TV or a television receiver), digital signage, and a public information display (PID) are given. Larger digital signage, PID, and the like can provide the increased amount of information, and attract more attention when used for advertisement or the like, so that the effectiveness of the advertisement is expected to be increased. 
     Examples of the display device include, typically, a light-emitting device including a light-emitting element such as an organic electroluminescent (EL) element or a light-emitting diode (LED), a liquid crystal display device, and an electronic paper performing display by an electrophoretic method or the like. 
     For example, in a basic structure of an organic EL element, a layer containing a light-emitting organic compound is provided between a pair of electrodes. By voltage application to this element, the light-emitting organic compound can emit light. A display device including such an organic EL element needs no backlight which is necessary for liquid crystal display devices and the like; therefore, thin, lightweight, high contrast, and low power consumption display devices can be obtained. For example, Patent Document 1 discloses an example of a display device including an organic EL element. 
     Furthermore, Patent Document 2 discloses a flexible active matrix light-emitting device in which an organic EL element and a transistor serving as a switching element are provided over a film substrate. 
     REFERENCES 
     Patent Documents 
     
         
         [Patent Document 1] Japanese Published Patent Application No. 2002-324673 
         [Patent Document 2] Japanese Published Patent Application No. 2003-174153 
       
    
     DISCLOSURE OF INVENTION 
     An object of one embodiment of the present invention is to provide a display device that is suitable for increasing in size. Another object of one embodiment of the present invention is to provide a display device in which display unevenness is suppressed. Another object of one embodiment of the present invention is to provide a display device capable of uniform display in a display surface. Another object of one embodiment of the present invention is to provide a display device capable of display in which a joint portion in a display surface is hardly seen. 
     Another object is to provide a novel display device. 
     Note that the descriptions of these objects do not disturb the existence of other objects. In one embodiment of the present invention, there is no need to achieve all the objects. Objects other than the above objects will be apparent from and can be derived from the description of the specification and the like. 
     One embodiment of the present invention is a display device including two display panels, two plates, two stages, two driver circuits, two adjusting units, and a frame. The frame includes a plurality of pillars, a plurality of beams, and a plurality of bottom plates. The adjusting units have a function of adjusting positions and angles of the stages and are fixed to the frame. The driver circuits have a function of outputting signals for driving the display panels. The stages are fixed to the adjusting units and include regions provided with the driver circuits and the plates. The plates include first surfaces provided with mechanisms for connection to the stages and include convexly curved surfaces. Each display panel includes a display portion, an operating circuit portion, a terminal, an external electrode, a transparent portion, and a first portion and has flexibility. The display portion has a function of displaying an image. The operating circuit portion includes a circuit having a function of outputting a signal to the display portion and a wiring capable of electrically connecting the circuit to the terminal. The operating circuit is located in a region adjacent to the display portion. The terminal is electrically connected to the external electrode. The external electrode has a function of transmitting the signal output from the driver circuit to the operating circuit portion. The transparent portion includes a region transmitting visible light and is located in a region not overlapping with the operating circuit portion and adjacent to one side of the display portion. In each display panel, the first portion includes a region between the terminal and the display portion. Surfaces opposite to image display surfaces of the display panels are fixed to second surfaces opposite to the first surfaces of the plates so that the transparent portions and parts of the display portions extend beyond the plates. The first portions are provided along the convexly curved surfaces. The display portion of one of the two display panels overlaps with the transparent portion of the other display panel. 
     The display device further including a video signal divider and a video output unit is also one embodiment of the present invention. The video output unit has a function of outputting a video signal or an image signal to the video signal divider. The video signal divider has a function of dividing the video signal or the image signal into a plurality of signals and outputting the signals to the driver circuits. 
     The display device in which, in each display panel, the transparent portion is located in a region not overlapping with the operating circuit portion and adjacent to two sides of the display portion, and the first portion of one of the two display panels overlaps with the first portion of the other display panel is also one embodiment of the present invention. 
     In the display device, the driver circuits preferably have a function of adjusting color tone, luminance, or the like of images or video that is to be displayed on the display panels. 
     The display device in which the display portions each include a plurality of pixels, the pixels each include a light-emitting element and a transistor, and each light-emitting element includes a lower electrode, an upper electrode, and an EL layer between the lower electrode and the upper electrode is also one embodiment of the present invention. 
     The display device in which the display portions each include an auxiliary electrode and the auxiliary electrode is in contact with the upper electrode in a region between adjacent lower electrodes is also one embodiment of the present invention. 
     One embodiment of the present invention can provide a display device that is suitable for increasing in size. One embodiment of the present invention can provide a display device in which display unevenness is suppressed. One embodiment of the present invention can provide a display device capable of uniform display in a display surface. One embodiment of the present invention can provide a display device capable of display in which a joint portion in a display surface is hardly seen. 
     One embodiment of the present invention can provide a novel display device. Note that the description of these effects does not disturb the existence of other effects. One embodiment of the present invention does not necessarily achieve all the effects listed above. Other effects will be apparent from and can be derived from the description of the specification, the drawings, the claims, and the like. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       In the accompanying drawings: 
         FIGS. 1A to 1C  illustrate a display device according to one embodiment; 
         FIGS. 2A and 2B  illustrate a display device according to one embodiment; 
         FIGS. 3A and 3B  each illustrate a display device according to one embodiment; 
         FIGS. 4A to 4D  illustrate a display device according to one embodiment; 
         FIGS. 5A and 5B  illustrate a display device according to one embodiment; 
         FIGS. 6A to 6D  illustrate a display panel according to one embodiment; 
         FIGS. 7A to 7C  illustrate a display panel according to one embodiment; 
         FIGS. 8A to 8C  each illustrate a positional relation between display panels according to one embodiment; 
         FIGS. 9A to 9C  illustrate display panels according to one embodiment; 
         FIG. 10  illustrates a display panel according to one embodiment; 
         FIGS. 11A, 11B, 11C ,  11 D 1 , and  11 D 2  illustrate display panels according to one embodiment; 
         FIG. 12  is a circuit diagram of a pixel of a display panel according to one embodiment; 
         FIGS. 13A and 13B  are each a circuit diagram of a pixel of a display panel according to one embodiment; 
         FIGS. 14A and 14B  are each a circuit diagram of a pixel of a display panel according to one embodiment; 
         FIGS. 15A and 15B  are each a circuit diagram of a pixel of a display panel according to one embodiment; 
         FIGS. 16A and 16B  are each a circuit diagram of a pixel of a display panel according to one embodiment; 
         FIGS. 17A and 17B  illustrate display panels according to one embodiment; 
         FIGS. 18A to 18C  illustrate a touch panel according to one embodiment; 
         FIGS. 19A and 19B  illustrate a touch panel according to one embodiment; 
         FIGS. 20A to 20C  illustrate touch panels according to one embodiment; 
         FIGS. 21A to 21C  illustrate touch panels according to one embodiment; 
         FIGS. 22A to 22D  illustrate touch panels according to one embodiment; 
         FIGS. 23A to 23D  illustrate touch panels according to one embodiment; 
         FIGS. 24A to 24C  illustrate touch panels according to one embodiment; 
         FIGS. 25A to 25F  illustrate touch panels according to one embodiment; 
         FIG. 26  illustrates a touch panel according to one embodiment; 
         FIG. 27  illustrates a touch panel according to one embodiment; 
         FIGS. 28A and 28B  are photographs of a display panel according to one example; 
         FIG. 29  is a photograph of a display device according to one example; 
         FIGS. 30A and 30B  are photographs of a display panel according to one example; 
         FIGS. 31A and 31B  are photographs of a display device according to one example; 
         FIG. 32  is a photograph of a display device according to one example; 
         FIGS. 33A and 33B  are photographs of a display device according to one example; and 
         FIG. 34  is a photograph of a display device according to one example. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Embodiments will be described in detail with reference to drawings. Note that the present invention is not limited to the description below, and it is easily understood by those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. Accordingly, the present invention should not be interpreted as being limited to the content of the embodiments below. 
     Note that in the structures of the invention described below, the same portions or portions having similar functions are denoted by the same reference numerals in different drawings, and description of such portions is not repeated. Further, the same hatching pattern is applied to portions having similar functions, and the portions are not especially denoted by reference numerals in some cases. 
     Note that in each drawing described in this specification, the size, the layer thickness, or the region of each component is exaggerated for clarity in some cases. Therefore, embodiments of the present invention are not limited to such a scale. 
     Note that in this specification and the like, ordinal numbers such as “first”, “second”, and the like are used in order to avoid confusion among components and do not limit the number. 
     Note that in this specification, the description “A has a shape such that an end portion extends beyond an end portion of B” may indicate, for example, the case where at least one of end portions of A is positioned on an outer side than at least one of end portions of B in a top view or a cross-sectional view. 
     Note that the terms “film” and “layer” can be interchanged with each other depending on the case or circumstances. For example, the term “conductive layer” can be changed into the term “conductive film” in some cases. Also, the term “insulating film” can be changed into the term “insulating layer” in some cases. 
     [Embodiment 1] 
     In this embodiment, structure examples of a display device of one embodiment of the present invention are described with reference to drawings. 
     In each of two display panels included in the display device of one embodiment of the present invention, a transparent portion is provided adjacent to one side of a display portion. The display portion has a function of displaying an image, and the transparent portion transmits light emitted from the display portion. The two display panels are arranged to overlap with each other, and the transparent portion of one of the display panels and the display portion of the other display panel are arranged to overlap with each other. Thus, the display device can perform large-area display in which the joint portion of the display portions is hardly seen. 
     Each component of the display device will be described in detail below. 
       FIG. 1A  is a front view of a display device  20 A.  FIG. 1B  is a cross-sectional view of the display device  20 A along the dashed-dotted line Y 1 -Y 2  in  FIG. 1A . 
     The display device  20 A includes two display panels  40 , two plates  50 , two stages  61 , two driver circuits  62 , two adjusting units  63 , and a frame  21 A. 
     Note that one of two components in the display device  20 A is denoted by a reference numeral with the letter “a”, and the other is denoted by a reference numeral with the letter “b”. Note that in describing common parts of the two components, the two components are denoted by reference numerals without the letters “a” and “b” in some cases. The same can apply to two components included in a display device  10  and a display device  20 B which will be described later. 
       FIGS. 2A and 2B  show the display device  20 A from which the plates  50  and the display panels  40  are removed.  FIG. 2A  is a front view of the display device  20 A.  FIG. 2B  is a cross-sectional view of the display device  20 A along the dashed-dotted line Y 3 -Y 4  in  FIG. 2A . Components of the display device  20 A which are not shown in  FIG. 1A  and their reference numerals are shown in  FIG. 2A . 
     In the display device  20 A, the display panel  40  is attached to the plate  50  with a part of the display panel  40  bent (see  FIG. 1B ).  FIG. 1C  is a top view of the display panel  40  placed alone on a flat surface. 
     In the display device  20 A, a display portion  41   a  of the display panel  40   a  and a display portion  41   b  of the display panel  40   b  are arranged seamlessly. Thus, a display portion  11 A can be used as one display region displaying an image or video. The display portion  11 A is a region surrounded by a thick dashed line in  FIG. 1A . 
     The frame  21 A includes a plurality of pillars and a plurality of beams. The frame  21 A can be provided with the two adjusting units  63 . In this embodiment, the adjusting units  63  are fixed to the beams of the frame  21 A (see  FIG. 2A ). 
     The frame  21 A can be formed of a metal material which is processed easily and not deformed easily. Examples of the metal material include aluminum; copper; manganese; magnesium; an alloy of aluminum, copper, manganese, or magnesium (an aluminum alloy); iron; chromium; nickel; and an alloy of iron, chromium, or nickel (stainless steel). 
     The adjusting unit  63  has a function of adjusting the position and the angle of the stage  61  fixed onto the adjusting unit  63 . Specifically, the adjusting unit  63  allows the display panel  40  connected to the stage  61  to move in an X-axis direction and/or a Y-axis direction or to rotate around a Z-axis. 
     The adjusting unit  63  can adjust the positions of the two display panels  40  so that the display portions  41   a  and  41   b  of the display panels  40  become parallel and have no space therebetween. 
     As the adjusting unit  63 , a one-axis stage (also referred to as an X-axis stage) for adjusting the position in the X-axis direction, a one-axis stage (also referred to as a Y-axis stage) for adjusting the position in the Y-axis direction, and a tilt stage (also referred to as a goniometer stage) for adjusting the position in a direction of rotation around the Z-axis in  FIG. 1B  can be used in combination. Alternatively, a two-axis stage for adjusting the position in the X-axis direction and the Y-axis direction and the tilt stage may be used in combination. In this embodiment, the adjusting unit  63  includes the X-axis stage, the Y-axis stage, and the goniometer stage in the order from the side fixed to the frame  21 A (see  FIGS. 2A and 2B ). 
     The driver circuit  62  has a function of converting an image signal or a video signal input to the driver circuit  62  to a signal for driving the display panel  40  and of outputting the converted signal to the display panel  40 . Furthermore, the driver circuit  62  has a function of supplying a power supply voltage required for light emission of the display panel  40 . 
     The driver circuit  62  preferably has a function of adjusting color tone, luminance, or the like in display of the display panel  40 , in which case variation can be corrected when the variation in display performance between the display panel  40   a  and the display panel  40   b  occurs. 
     The driver circuit  62  may have a function of generating an image signal or a video signal. A cable  64  may be connected to the driver circuit  62 . For example, a signal can be input to the driver circuit  62  from an external video output device through the cable  64  (see  FIG. 2B ). 
       FIG. 3A  is a side view illustrating the display device  10  of one embodiment of the present invention. The display device  10  includes the display device  20 A, a video signal divider  22 , and a video output unit  23 . In the display device  10 , for example, a frame  21  includes the frame  21 A and a plurality of bottom plates over which the video signal divider  22  and the video output unit  23  are provided. The frame  21  can be formed of a metal material similar to that of the frame  21 A. 
     In the display device  10 , the driver circuit  62   a  and the driver circuit  62   b  are electrically connected to the video signal divider  22  through the cable  64   a  and the cable  64   b , respectively. The video signal divider  22  is electrically connected to the video output unit  23  through a cable  65 . Note that the display panel  40 , the plate  50 , and the stage  61  are collectively referred to as a component group  60  ( 60   a  or  60   b ) in  FIG. 3A . 
     The video output unit  23  has a function of outputting, to the video signal divider  22 , a signal for an image or video that is to be displayed on the display panels  40   a  and  40   b . As the video output unit  23 , a recording/reproducing device such as a Blu-ray Disc recorder or a digital versatile disc (DVD) recorder can be used. 
     In the case where a plurality of display panels is arranged in a tile pattern to form the display device, an uncompressed disk recorder (UDR) capable of outputting an image with high resolution, e.g., 4K (3840×2160 pixels) or 8K (7680×4320 pixels), without compression can be favorably used as the video output unit  23 . The number of display panels arranged in a tile pattern is, for example, nine (3×3) or thirty-six (6×6). 
     The video signal divider  22  has a function of dividing an input signal for an image or video and outputting the divided signals to a plurality of driver circuits or display devices. 
     For example, in the case where an image signal for certain display resolution is divided into nine and the divided signals are output to nine display devices by the video signal divider  22 , an image displayed using an image signal output to and received by each display device provides a pixel aspect equal to an original image and 1/9 display resolution. Then, display regions of the nine display devices are arranged to correspond to the order in which the original image signal is divided. Thus, an image can be displayed with the display resolution of the original image. Note that here, the term “pixel aspect” refers to the ratio between the display resolution of an image in the longitudinal direction and the display resolution of the image in the horizontal direction. The term “display resolution” refers to the total number of pixels forming a display portion of a display device or the total number of pixels forming an image. 
     In this embodiment, the image signal or the video signal input to the video signal divider  22  is divided into two and the divided signals are output to the two driver circuits  62 . 
     Referring again to the display device  20 A, the stage  61  has a region where the driver circuit  62  can be provided and a region where the plate  50  can be provided (see  FIG. 1B ). Since the stage  61  has the region where the driver circuit  62  can be provided, the replacement of a component due to the specification change of the driver circuit  62  or maintenance can be performed easily, for example. 
     Note that the driver circuit  62  may be reduced in volume so as to be attached to the surface of the stage  61  opposite to the region where the plate  50  can be provided. This can reduce the region of the stage  61  where the driver circuit  62  is provided and accordingly can reduce the depth of the display device  20 A (the length in the Z-axis direction in  FIG. 1B ). 
     The stage  61  can be formed of a metal material similar to that of the frame  21 A. 
     The plate  50  includes a first surface provided with a mechanism for connection to the stage  61  and a side surface provided with a convexly curved surface (see  FIG. 1B ). The plate  50  includes a region where the display panel  40  is provided on a surface (hereinafter referred to as a second surface) opposite to the first surface. In this embodiment, the mechanism includes a depression  51  to which a part of the stage  61  can be fit and a fastening  52  capable of sliding in the Y-axis direction. However, the mechanism is not limited thereto. Note that not the plate  50 , but the stage  61  may include a mechanism for setting the plate  50  to the stage  61 . 
     The plate  50  needs to be connected precisely to the stage  61  to accurately adjust the relative positions of the display portion  41   a  and the display portion  41   b  using the adjusting unit  63 . The alignment of the plate  50  and the stage  61  in the Y-axis direction can be achieved using the depression  51  and the fastening  52 . The alignment of the plate  50  and the stage  61  in the X-axis direction can be achieved using guides  53  to be described later. 
     The plate  50  can be formed of a metal material similar to that of the frame  21 A. 
     The display panel  40  is provided with the display portion  41 , a transparent portion  42 , an operating circuit portion  43 , a terminal  45 , and an external electrode  46  (see  FIG. 1C ). The display panel  40  has flexibility. 
     The terminal  45  is electrically connected to a wiring in the operating circuit portion  43  and the external electrode  46 . The external electrode  46  is electrically connected to the driver circuit  62 , and a signal is output from the driver circuit  62  to the display panel  40  through the external electrode  46  (see  FIG. 1B ). In this embodiment, a flexible printed circuit (FPC) is used as an example of the external electrode  46 . 
     The display portion  41  has a function of displaying an image. The display portion  41  may include a light-emitting element such as an organic EL element. 
     The operating circuit portion  43  has a function of outputting a signal to the display portion  41 . The operating circuit portion  43  includes a scan line driver circuit, a signal line driver circuit, and the like. Wirings for connecting the external electrode  46  to the scan line driver circuit and the signal line driver circuit are also included in the operating circuit portion  43 . 
     In the display panel  40 , the operating circuit portion  43  is provided in a position adjacent to the display portion  41 . In the structure shown in  FIG. 1C , the operating circuit portion  43  is adjacent to two sides of the display portion  41 . The operating circuit portion  43  may be adjacent to one side of the display portion  41 . The operating circuit portion  43  may be a region which does not transmit visible light or a region which transmits visible light, depending on the structure of the scan line driver circuit or the like. 
     The transparent portion  42  includes a region which transmits visible light. A region where the transparent portion  42  is located is adjacent to the display portion  41  and does not overlap with the operating circuit portion  43 . 
     In the example shown in  FIG. 1C , the transparent portion  42  is adjacent to a bottom side of the display portion  41  (a side opposite to the side near the terminal  45 ); however, the position of the transparent portion  42  is not limited thereto. For example, the transparent portion  42  may be adjacent to a right side of the display portion  41  (a side opposite to a longer side of the display portion  41  which is adjacent to the operating circuit portion  43 ). 
     The transparent portion  42  may be adjacent to two sides of the display portion  41  (e.g., the bottom side and the right side). The transparent portion  42  adjacent to two sides of the display portion  41  is preferable because the display panels  40  can be seamlessly arranged in a tile pattern. Furthermore, when there is no space between the display portion  41  and the transparent portion  42 , large-area display can be performed in which a joint portion of the display panels  40  arranged in a tile pattern is hardly seen. 
     It is preferable that the transparent portion  42  have high transmittance, because the boundary between a region behind the transparent portion  42  and the other region is hardly seen in performing display on the display portion  41 . Furthermore, it is preferable that the refractive index of a material of the transparent portion  42  be close to 1 because the reflection of external light can be suppressed. 
     The width of the transparent portion  42  (the length of the transparent portion  42  in the Y-axis direction in  FIG. 1B ) is equal to the distance between an end portion of the display panel  40  and a side of the display portion  41  which is adjacent to the transparent portion  42  (see  FIG. 1C ). The transparent portion  42  may include a sealing layer having a function of suppressing the entry of an impurity such as water into the light-emitting element of the display portion  41 . That is, the width of the transparent portion  42  can be set depending on the sealing performance of the sealing layer and/or reliability required for the light-emitting element. 
     A specific structure of the display panel will be described in detail in Embodiment 2. 
       FIG. 1B  shows a structure in which the two display panels  40  are arranged in the Y-axis direction so that the display portion  41   a  and the display portion  41   b  are arranged seamlessly. 
     Note that in the two display panels shown in  FIGS. 1A and 1B , the display panel located on the rear side (the display panel whose front surface is overlapped by the transparent portion  42  of the other display panel) is denoted by  40   a , and the display panel located on the front side is denoted by  40   b . Note that the positional relation and the connection relation between the display panel  40   a  and the plate  50   a  are equal to the positional relation and the connection relation between the display panel  40   b  and the plate  50   b.    
     In  FIG. 1B , the display panel  40  has a surface where display on the display portion  41  can be seen and a surface opposite thereto (hereinafter the latter surface is referred to as a display rear surface), and the display rear surface is in contact with the second surface and the convexly curved surface of the plate  50 . 
     The display rear surface and the second surface may adhere to each other or be fixed to each other to be attachable to and detachable from each other. In the case where the display rear surface and the second surface are attachable to and detachable from each other, the display panel  40  can be replaced easily. 
     For example, a film having an adsorbing property (hereinafter referred to as an adsorptive film) can be used to make the display rear surface and the second surface attachable to and detachable from each other. Air between an object and the adsorptive film is removed to produce a low-pressure or vacuum state therebetween, so that the adsorptive film can be attached to the object. Alternatively, an adhesive film may be used to make the display rear surface and the second surface attachable to and detachable from each other. 
     In the case of using the adsorptive film or the adhesive film to fix the display rear surface and the second surface to each other, the film is attached to the second surface first. The film may be attached to either the whole area of the second surface or a part thereof. In the latter case, the film is preferably attached to at least a region of the second surface in the vicinity of the convexly curved surface. This can prevent the display panel  40  in the vicinity of an upper portion of the display portion  41  from being apart from the second surface in the case where a first portion  44  of the display panel  40  is bent along the convexly curved surface. 
     In the display panel  40 , a region between the terminal  45  and the display portion  41  is the first portion  44  (see  FIG. 1C ). The first portion  44  is preferably provided along the convexly curved surface of the plate  50  as shown in  FIG. 1B . 
     Furthermore, it is preferable that the first portion  44  and the convexly curved surface not be fixed to each other. Such a structure can enlarge the movable area of the external electrode  46  and increase the degree of flexibility in connection between the external electrode  46  and the driver circuit  62 . In addition, two display panels  80  can be arranged easily in the X-axis direction as described later. 
     Note that the first portion  44  of the display panel  40  is not necessarily provided along the whole area of the convexly curved surface of the plate  50  and may be provided along a part of the convexly curved surface as shown in  FIG. 3B . Such a structure can increase the curvature radius of the first portion  44  and reduce physical stress applied to the display panel  40  accordingly. 
     As shown in  FIG. 1B , the display panel  40   b  is fixed to the plate  50   b  so that the transparent portion  42   b  and a part of the display portion  41   b  extend beyond the plate  50   b . The part of the display portion  41   b  extending beyond the plate  50   b  allows the display portion  41   b  to be placed on the display panel  40   a  without contact between the plate  50   b  and the first portion  44   a.    
     For example, the length in the Y-axis direction of the part of the display portion  41   b  extended beyond the plate  50   b  can be determined by making the top side of the display portion  41   a  align with the bottom side of the display portion  41   b  in the Z-axis direction. 
     It is preferable that, in a portion where the transparent portion  42   b  and the display portion  41   a  are in contact with each other, air and the like not be present between the transparent portion  42   b  and the display portion  41   a . Furthermore, it is preferable that the transparent portion  42   b  and the display portion  41   a  be attachable to and detachable from each other. 
     The above-described adsorptive film can be used to make the transparent portion  42   b  and the display portion  41   a  attachable to and detachable from each other. In the case of using the adsorptive film, it is preferable that the difference between the refractive index of the material of the transparent portion  42   b  and the refractive index of a material of the adsorptive film be small. This can suppress the reflection of external light at the interface between the transparent portion  42   b  and the adsorptive film and increase visibility of display on the display portion  41   a  in a region overlapping with the transparent portion  42   b.    
     Since the display panels  40  have flexibility, the plates  50   a  and  50   b  can be arranged so that the second surfaces thereof form one plane and a part of the display panel  40   b  extending beyond the plate  50   b  can be bent and placed on the surface of the display panel  40   a.    
     By arranging the plates  50   a  and  50   b  so that the second surfaces thereof form one plane, a display surface of the display portion  11 A can be made approximately flat without steps. 
     The process for setting the display panels  40   a  and  40   b  to form the display device  20 A is described below with reference to  FIGS. 1A and 1B  and  FIGS. 2A and 2B . 
     Note that the adjusting units  63   a  and  63   b  and the stages  61   a  and  61   b  are provided for the frame  21 A in advance. First, the driver circuits  62   a  and  62   b  are set onto the stages  61   a  and  61   b , respectively (see  FIGS. 2A and 2B ). 
     Then, the plate  50   a  is made to adhere to the display panel  40   a  or fixed to the display panel  40   a  so as to be attachable thereto and detachable therefrom. Specifically, the display rear surface of the display panel  40   a  and the second surface of the plate  50   a  are disposed in close contact with each other with the adsorptive film or the film having an adhesion property. At this time, it is preferable that the first portion  44   a  and the convexly curved surface of the plate  50   a  not be fixed to each other. 
     The plate  50   a  is provided for the stage  61   a . Specifically, a part of the stage  61   a  is fit into the depression  51   a , and the first surface of the plate  50   a  is made to overlap with a side surface of the stage  61   a  so as to be in contact with each other. After that, the fastening  52   a  is slid up to fix the plate  50   a  to the stage  61   a . Then, the external electrode  46   a  and the driver circuit  62   a  are connected to each other. 
     Next, the display panel  40   b  is fixed to the plate  50   b  in a manner similar to the above-described manner in which the display panel  40   a  is fixed to the plate  50   a.    
     The plate  50   b  is provided for the stage  61   b . The plate  50   b  can be provided for the stage  61   b  in a manner similar to the above-described manner in which the plate  50   a  is provided for the stage  61   a . Note that the plate  50   b  is provided such that the part of the display panel  40   b  extended beyond the plate  50   b  is located on the front surface of the display panel  40   a . Then, the external electrode  46   b  and the driver circuit  62   b  are connected to each other. 
     Note that when the plate  50   b  is provided for the stage  61   b , the stage  61   a  may be moved in the Y-axis direction using the adjusting unit  63   a  so that the plate  50   b  does not contact the first portion  44   a  in contact with the convexly curved surface of the plate  50   a . Alternatively, the stage  61   b  may be moved in the Y-axis direction using the adjusting unit  63   b.    
     Then, the position or the angle of the display portion  41   a  is adjusted using the adjusting unit  63   a  and/or the position or the angle of the display portion  41   b  is adjusted using the adjusting unit  63   b  so that the joint portion of the display portions  41   a  and  41   b  is hardly seen when the display portion  11 A is seen in the Z-axis direction. 
     In one method for relative alignment of the display portions  41   a  and  41   b , for example, an image is displayed on the display portion  11 A as one display area, and then, a discontinuous portion of the image at or in the vicinity of the boundary between the display portions  41   a  and  41   b  is made as small as possible using the adjusting unit  63   a  and/or the adjusting unit  63   b . As the image to be displayed on the display portion  11 A at this time, for example, an image having a stripe-like scale crossing the discontinuous portion is used, in which case the relative alignment of the display portions  41   a  and  41   b  can be easily performed. 
     Finally, the transparent portion  42   b  and the display portion  41   a  are fixed to each other so as to be attachable to and detachable from each other while air is prevented from being present therebetween (see  FIGS. 1A and 1B ). For example, the adsorptive film can be used to fix them so as to be attachable to and detachable from each other. 
     Through the above-described process, the display panels  40   a  and  40   b  can be set in the display device  10 . 
     [Modification Example 1] 
     In this embodiment described so far, the structure of the display device  20 A in which the two display panels are adjacent to each other in the Y-axis direction is described. In Modification Example 1, a structure of a display device  20 B in which two display panels are adjacent to each other in the X-axis direction will be described. 
     Note that only differences between the display device  20 B and the display device  20 A shown in  FIGS. 1A and 1B  will be described below. 
       FIG. 4A  is a front view of the display device  20 B in which two display panels  80   a  and  80   b  are arranged in the X-axis direction.  FIG. 4B  is a cross-sectional view of the display device  20 B along the dashed-dotted line Y 5 -Y 6  in  FIG. 4A . Note that in the two display panels shown in  FIGS. 4A and 4B , the display panel located on the rear side is denoted by  80   a , and the display panel located on the front side is denoted by  80   b.    
     In the display device  20 B, the display panel  80  is attached to the plate  90  with a part of the display panel  80  bent (see  FIG. 4B ).  FIG. 4C  is a top view of the display panel  80  placed alone on a flat surface. 
       FIGS. 5A and 5B  show the display device  20 B from which the plates  90  and the display panels  80  are removed.  FIG. 5A  is a front view of the display device  20 B.  FIG. 5B  is a cross-sectional view of the display device  20 B along the dashed-dotted line Y 7 -Y 8  in  FIG. 5A . Components of the display device  20 B which are not shown in  FIG. 4A  and their reference numerals are shown in  FIG. 5A . 
     In the display device  20 B, the display portion  41   a  of the display panel  80   a  and the display portion  41   b  of the display panel  80   b  are arranged seamlessly. Thus, a display portion  11 B can be used as one display region displaying an image or video. The display portion  11 B is a region surrounded by a thick dashed line in  FIG. 4A . 
     A frame  21 B differs from the frame  21 A shown in  FIG. 2A  in that the frame  21 B includes a plurality of pillars and a plurality of beams with which the two display panels  80  are arranged in the X-axis direction (see  FIG. 5A ). 
       FIG. 4D  is a rear view of a stage  91  and a plate  90  in a state where the plate  90  is provided for the stage  91 . In the stage  91 , the width (the length in the X-axis direction) of a lower portion of a region where the plate  90  is provided is smaller than the width of an upper portion of the region where the plate  90  is provided, which is different from that in the stage  61 . A first surface of the plate  90  is provided with the guides  53 . The distance between the two guides  53  is equal to the width of the lower portion of the stage  91  and is indicated by W 1 . With such a structure, the positions of the plate  90  and the stage  91  in the X-axis direction can be aligned with high precision at the time of attaching the plate  90  to the stage  91 . 
     The frame  21 B and the stage  91  can be formed of a metal material similar to that of the frame  21 A. The frame  21 B and the stage  91  may be formed of different materials. 
     The display panel  80  is provided with a transparent portion  82  in a position adjacent to the right side and the lower side of the display portion  41  (see  FIG. 4C ). As shown in  FIG. 4A , the display portion  41   a  and the transparent portion  82   b  overlap with each other in the display device  20 B. Furthermore, the first portion  44   a  of the display panel  80   a  and the first portion  44   b  of the display panel  80   b  overlap with each other. Such a structure allows a plurality of display panels  80  to be arranged in the X-axis direction and the Y-axis direction without the joint portion of the display portions  41 , achieving large-area display. Note that  FIGS. 1A and 1B  and the description relating to  FIGS. 1A and 1B  in this specification can be referred to for a method of arranging the display panels  80  in the Y-axis direction. 
     The display panel  80   b  is fixed to the plate  90   b  so that the transparent portion  82   b  and a part of the display portion  41   b  extend beyond the plate  90   b  in the X-axis direction and the Y-axis direction (see  FIG. 4A ). 
     For example, the length in the X-axis direction of the part of the display portion  41   b  extended beyond the plate  90   b  can be determined by making the right side of the display portion  41   b  align with the left side of the display portion  41   a  in the Z-axis direction. 
     The process for setting the display panels  80   a  and  80   b  to form the display device  20 B is described below with reference to  FIGS. 4A to 4D  and  FIGS. 5A and 5B . 
     Note that the adjusting units  63   a  and  63   b  and stages  91   a  and  91   b  are provided for the frame  21 B in advance. First, the driver circuits  62   a  and  62   b  are set onto the stages  91   a  and  91   b , respectively (see  FIGS. 5A and 5B ). 
     Then, the plate  90   a  is made to adhere to the display panel  80   a  or fixed to the display panel  80   a  so as to be attachable thereto and detachable therefrom. Specifically, the display rear surface of the display panel  80   a  and the second surface of the plate  90   a  are disposed in close contact with each other with the adsorptive film or the film having an adhesion property. At this time, it is preferable that the first portion  44   a  and the convexly curved surface of the plate  90   a  not be fixed to each other. 
     The plate  90   a  is provided for the stage  91   a . Specifically, a part of the stage  91   a  is fit into the depression  51   a , and the plate  90   a  is moved in the X-axis direction so that a lower portion of the stage  91   a  is positioned between the two guides  53   a . Then, the first surface of the plate  90   a  is made to overlap with a side surface of the stage  91   a  so that they are in contact with each other. After that, the fastening  52   a  is pulled up to fix the plate  90   a  to the stage  91   a . Then, the external electrode  46   a  and the driver circuit  62   a  are connected to each other. 
     Next, the display panel  80   b  is fixed to the plate  90   b  in a manner similar to the above-described manner in which the display panel  80   a  is fixed to the plate  90   a . Note that a convexly curved surface of the plate  90   b  and the first portion  44   b  are not fixed to each other. 
     The plate  90   b  is provided for the stage  91   b . The plate  90   b  can be provided for the stage  91   b  in a manner similar to the above-described manner in which the plate  90   a  is provided for the stage  91   a . Note that the plate  90   b  is provided such that the part of the display panel  80   b  extended beyond the plate  90   b  is located on the front surface of the display panel  80   a.    
     Note that when the plate  90   b  is attached to the stage  91   b , the stage  91   a  may be moved in the X-axis direction using the adjusting unit  63   a  so that the plate  90   b  does not contact the display panel  80   a . Alternatively, the stage  91   b  may be moved in the X-axis direction using the adjusting unit  63   b.    
     Then, the position or the angle of the display portion  41   a  is adjusted using the adjusting unit  63   a  or the position or the angle of the display portion  41   b  is adjusted using the adjusting unit  63   b  so that the joint portion of the display portions  41   a  and  41   b  is hardly seen when the display portion  11 B is seen in the Z-axis direction. 
     Finally, the transparent portion  82   b  and the display portion  41   a  are fixed to each other so as to be attachable to and detachable from each other while air is prevented from being present therebetween (see  FIGS. 4A and 4B ). For example, the adsorptive film can be used to fix them so as to be attachable to and detachable from each other. 
     Finally, the first portion  44   b  is placed along the convexly curved surface of the plate  90   a  and the first portion  44   a , and the external electrode  46   b  is connected to the driver circuit  62   b.    
     Note that a curvature radius of a bent portion of the first portion  44   b  is longer than a curvature radius of a bent portion of the first portion  44   a  because the first portion  44   b  overlaps the first portion  44   a . Therefore, the external electrode  46   b  required for connection between the display panel  80   b  and the driver circuit  62   b  is longer than the external electrode  46   a  required for connected between the display panel  80   a  and the driver circuit  62   a  (see  FIG. 4A ). This means that excess tension is generated in the external electrode  46   b  and the terminal  45   b  when the display panel  80   b  and the driver circuit  62   b  are connected to each other. Thus, the length of the external electrode  46   b  or the first portion  44   b  in the longitudinal direction of the display panel  80   b  is preferably adjusted. A connection position of the driver circuit  62   b  and the external electrode  46   b  may be adjusted. 
     [Structure Example of Display Portion] 
     Next, a structure example of a display portion of a display panel included in a display device of one embodiment of the present invention will be described.  FIG. 6A  is a top view of a display panel  30  in which a transparent portion  32  is adjacent to two sides of the display portion  41 .  FIG. 6B  is a top view in which a region P in  FIG. 6A  is enlarged, and  FIG. 6C  is a top view in which a region Q in  FIG. 6A  is enlarged. 
     As illustrated in  FIG. 6C , in the display portion  41 , a plurality of pixels  31  is arranged in a matrix. In the case where the display panel  30  which is capable of full color display with three colors of red, blue, and green is formed, the pixel  31  can display any of the three colors. Alternatively, a pixel which can display white or yellow in addition to the three colors may be provided. A region including the pixels  31  corresponds to the display portion  41 . 
     One pixel  31  is electrically connected to a wiring  34   c  and a wiring  34   d . The plurality of wirings  34   c  each intersects with the wiring  34   d , and is electrically connected to an operating circuit  33   c . The plurality of wirings  34   d  is electrically connected to an operating circuit  33   d . One of the operating circuits  33   c  and  33   d  can function as a scan line driver circuit, and the other can function as a signal line driver circuit. A structure without one of the operating circuits  33   c  and  33   d  or both of them may be employed. 
     In  FIG. 6B , a plurality of wirings  35  electrically connected to the operating circuit  33   c  or the operating circuit  33   d  is provided. The wiring  35  is electrically connected to the external electrode  46  in a region not shown in the figure and has a function of supplying a signal from the outside to the operating circuits  33   c  and  33   d.    
     In  FIG. 6B , a region including the operating circuit  33   c , the operating circuit  33   d , and the plurality of wirings  35  corresponds to the operating circuit portion  43  in  FIG. 6A . 
     In  FIG. 6C , a region outside the pixel  31  provided closest to the end corresponds to the transparent portion  32 . The transparent portion  32  does not include the members blocking visible light, such as the pixel  31 , the wiring  34   c , and the wiring  34   d . Note that in the case where part of the pixel  31 , the wiring  34   c , or the wiring  34   d  transmits visible light, the part of the pixel  31 , the wiring  34   c , or the wiring  34   d  may be provided to extend to the transparent portion  32 . 
     Here, the width W 2  of the transparent portion  32  indicates the narrowest width of the transparent portion  32  provided in the display panel  30  in some cases. In the case where the width W 2  of the display panel  30  varies depending on the positions, the width of the shortest portion can be referred to as the width W 2 . In  FIG. 6C , the distance between the pixel  31  and the end surface of the substrate (that is, the width W 2  of the transparent portion  32 ) in the vertical direction is the same as that in the horizontal direction. 
       FIG. 6D  is a cross-sectional view taken along the dashed-dotted line X 1 -X 2  in  FIG. 6C . The display panel  30  illustrated in  FIG. 6D  includes a pair of substrates (a substrate  36  and a substrate  37 ) each of which transmits visible light. The substrate  36  and the substrate  37  are bonded to each other with an adhesive layer  38 . The pixel  31 , the wiring  34   d , and the like are provided for the substrate  36 . 
     As illustrated in  FIGS. 6C and 6D , in the case where the pixel  31  is positioned closest to the end of the display portion  41 , the width W 2  of the transparent portion  42  is the distance between the end portion of the substrate  36  or the substrate  37  and the end portion of the pixel  31 . 
     Note that the end portion of the pixel  31  refers to the end portion of the member that is positioned closest to the end and blocks visible light in the pixel  31 . Alternatively, in the case where a light-emitting element including a layer containing a light-emitting organic compound between a pair of electrodes (also referred to as an organic EL element) is used as the pixel  31 , the end portion of the pixel  31  may be any of the end portion of the lower electrode, the end portion of the layer containing a light-emitting organic compound, and the end portion of the upper electrode. 
       FIG. 7A  shows the case where the position of the wiring  34   c  is different from that in  FIG. 6C .  FIG. 7B  is a cross-sectional view taken along dashed-dotted line Y 9 -Y 10  in  FIG. 7A , and  FIG. 7C  is a cross-sectional view taken along dashed-dotted line X 3 -X 4  in  FIG. 7A . 
     As illustrated in  FIGS. 7A to 7C , in the case where the wiring  34   c  is positioned closest to the end of the display portion  41 , the width W 2  of the transparent portion  32  is the distance between the end portion of the substrate  36  or the substrate  37  and the end portion of the wiring  34   c . In the case where the wiring  34   c  transmits visible light, the transparent portion  32  may include a region where the wiring  34   c  is provided. 
     Here, in the case where the density of pixels provided in the display portion  41  of the display panel  30  is high, misalignment may occur when the two display panels  30  are bonded. 
       FIG. 8A  shows a positional relationship between the display portion  41   a  of the display panel  30   a  provided on the rear side and the display portion  41   b  of the display panel  30   b  provided on the front side, seen from the display surface side.  FIG. 8A  shows the vicinities of the corner portions of the display portions  41   a  and  41   b . Part of the display portion  41   a  is covered with the transparent portion  32   b.    
       FIG. 8A  shows an example in which adjacent pixels  31   a  and  31   b  are relatively deviated in one direction (X-axis direction). The arrow in the drawing denotes a direction in which the display panel  30   a  is deviated from the display panel  30   b .  FIG. 8B  shows an example in which the adjacent pixels  31   a  and  31   b  are relatively deviated in a vertical direction and a horizontal direction (X-axis direction and Y-axis direction). 
     In the examples of  FIGS. 8A and 8B , the distances deviated in the vertical direction and the horizontal direction are each shorter than the length of one pixel. In this case, image data of the image displayed on either one of the display portions  41   a  and  41   b  is corrected depending on the deviation distance, whereby the display quality can be maintained. Specifically, when the deviation makes the distance between the pixels smaller, the data is corrected so that the gray level (luminance) of the pixels is low, and when the deviation makes the distance between the pixels larger, the data is corrected so that the gray level (luminance) of the pixels is high. Alternatively, when the pixels are deviated by a distance of more than one pixel, the data is corrected so that the pixel positioned on a rear side is not driven and the image data is shifted by one column. 
       FIG. 8C  shows an example in which the pixels  31   a  and  31   b  , which should be adjacent, are relatively deviated in one direction (X-axis direction) by a distance of more than one pixel. When the deviation of more than one pixel occurs, the pixels are driven so that projecting pixels (pixels which are hatched) are not displayed. Note that the same applies to the case where the deviation direction is the Y-axis direction. 
     When the plurality of display panels  30  are made to overlap with each other, in order to suppress misalignment, each of the display panels  30  is preferably provided with an alignment marker or the like. Alternatively, a projection and a depression may be formed on the surfaces of the display panels  30 , and the projection and the depression may be attached to each other in a region where the two display panels  30  overlap. 
     Furthermore, in consideration of alignment accuracy, it is preferable that pixels more than the pixels to be used be placed in advance in the display portion  41  of the display panel  30 . For example, it is preferable that one or more, preferably three or more, further preferably five or more extra pixel columns along either one or both of a scan line and a signal line be provided in addition to the pixel columns used for display. 
     This embodiment can be combined with any other embodiment as appropriate. 
     [Embodiment 2] 
     In this embodiment, structure examples of a display panel which can be used in a display device of one embodiment of the present invention are described with reference to drawings. 
     Although a display panel mainly including an organic EL element is described in this embodiment as an example, a display panel which can be used in a display device of one embodiment of the present invention is not limited to this example. A light-emitting panel or a display panel including another light-emitting element or display element which will be described later in this embodiment as an example can also be used in a display device of one embodiment of the present invention. 
     [Structure Example 1] 
       FIG. 9A  is a plan view of the display panel, and  FIG. 9C  is an example of a cross-sectional view taken along the dashed-dotted line A 1 -A 2  in  FIG. 9A .  FIG. 9C  also shows an example of a cross-sectional view of a transparent portion  810 . 
     The display panel in Structure Example 1 is a top-emission display panel using a color filter method. In this embodiment, the display panel can have a structure in which subpixels of three colors of red (R), green (G), and blue (B), for example, express one color; a structure in which subpixels of four colors of R, G, B, and white (W) express one color; a structure in which subpixels of four colors of R, G, B, and yellow (Y) express one color; or the like. There is no particular limitation on color elements, and colors other than R, G, B, W, and Y may be used. For example, cyan, magenta, or the like may be used. 
     The display panel shown in  FIG. 9A  includes the transparent portion  810 , a display portion  804 , an operating circuit portion  806 , and an FPC  808 . The transparent portion  810  is adjacent to the display portion  804  and provided along two sides of the display portion  804 . The operating circuit portion  806  includes a scan line driver circuit, a signal line driver circuit, and the like. 
     The display panel illustrated in  FIG. 9C  includes a substrate  701 , an adhesive layer  703 , an insulating layer  705 , a plurality of transistors, a conductive layer  857 , an insulating layer  815 , an insulating layer  816 , an insulating layer  817 , a plurality of light-emitting elements, an insulating layer  821 , an adhesive layer  822 , a coloring layer  845 , a light-blocking layer  847 , an insulating layer  715 , an adhesive layer  713 , and a substrate  711 . The adhesive layer  822 , the insulating layer  715 , the adhesive layer  713 , and the substrate  711  transmit visible light. Light-emitting elements and transistors included in the display portion  804  and the operating circuit portion  806  are sealed with the insulating layer  705 , the insulating layer  715 , and the adhesive layer  822 . 
     The display portion  804  includes a transistor  820  and a light-emitting element  830  over the substrate  701  with the adhesive layer  703  and the insulating layer  705  provided therebetween. The light-emitting element  830  includes a lower electrode  831  over the insulating layer  817 , an EL layer  833  over the lower electrode  831 , and an upper electrode  835  over the EL layer  833 . That is, the light-emitting element  830  includes the lower electrode  831 , the upper electrode  835 , and the EL layer  833  provided between the lower electrode  831  and the upper electrode  835 . 
     The lower electrode  831  is electrically connected to a source electrode or a drain electrode of the transistor  820 . An end portion of the lower electrode  831  is covered with the insulating layer  821 . The lower electrode  831  preferably reflects visible light. The upper electrode  835  transmits visible light. 
     In addition, the display portion  804  includes the coloring layer  845  overlapping with the light-emitting element  830  and the light-blocking layer  847  overlapping with the insulating layer  821 . The space between the light-emitting element  830  and the coloring layer  845  is filled with the adhesive layer  822 . 
     The insulating layer  815  and the insulating layer  816  have an effect of inhibiting diffusion of impurities to a semiconductor included in the transistors. As the insulating layer  817 , an insulating layer having a planarization function is preferably selected in order to reduce surface unevenness due to the transistor. 
     Note that the insulating layer  815  and/or the insulating layer  816  may be omitted in a region where a transistor is not provided in the display panel. In particular, it is preferable that the insulating layer  815  and/or the insulating layer  816  not be formed in the transparent portion  810  because the transmittance is improved.  FIGS. 9A to 9C  show structures in each of which the insulating layer  815  is not formed in the transparent portion  810 . For example, silicon nitride and silicon oxynitride can be used as the insulating layer  815  and the insulating layer  816 , respectively. 
     The operating circuit portion  806  includes a plurality of transistors over the substrate  701  with the adhesive layer  703  and the insulating layer  705  provided therebetween. In  FIG. 9C , one of transistors included in the operating circuit portion  806  is illustrated. 
     The insulating layer  705  and the insulating layer  715  are preferably highly resistant to moisture, in which case entry of impurities such as water into the light-emitting element  830  or the transistor  820  can be inhibited, leading to higher reliability of the display panel. When the display panel includes a substrate, the surface of the display panel can be protected from a physical impact, which is preferable. The substrate  701  is bonded to the insulating layer  705  with the adhesive layer  703 . The substrate  711  is bonded to the insulating layer  715  with the adhesive layer  713 . 
     The conductive layer  857  is electrically connected to an external electrode through which a signal (e.g., a video signal, a clock signal, a start signal, or a reset signal) or a potential from the outside is transmitted to the operating circuit portion  806 . Here, an example in which the FPC  808  is provided as the external electrode is described. To prevent an increase in the number of manufacturing steps, the conductive layer  857  is preferably formed using the same material and the same step(s) as those of the electrode or the wiring in the display portion or the driver circuit portion. Here, an example is described in which the conductive layer  857  is formed using the same material and the same step(s) as those of the electrodes of the transistor  820 . 
     In the display panel in  FIG. 9C , the FPC  808  is positioned over the insulating layer  715 . The connector  825  is connected to the conductive layer  857  through an opening provided in the insulating layer  715 , the adhesive layer  822 , the insulating layer  817 , the insulating layer  816 , and the insulating layer  815 . The connector  825  is also connected to the FPC  808 . The FPC  808  and the conductive layer  857  are electrically connected to each other via the connector  825 . 
       FIG. 10  shows an example of a cross-sectional view of a state where two display panels each shown in  FIG. 9C  are attached to each other with an adhesive layer  723  therebetween. Note that the two display panels may be fixed to each other so as to be attachable to and detachable from each other using an adsorptive layer instead of the adhesive layer  723 . 
       FIG. 10  shows the display portion  41   a  (corresponding to the display portion  804  shown in  FIG. 9A ) and the operating circuit portion  43   a  (corresponding to the operating circuit portion  806  and the like shown in  FIG. 9A ) of the lower (rear) display panel and the display portion  41   b  (corresponding to the display portion  804  shown in  FIG. 9A ) and the transparent portion  42   b  (corresponding to the transparent portion  810  shown in  FIG. 9A ) of the upper (front) display panel. Furthermore, the cross-sectional view shown in  FIG. 10  shows an example of an overlapping portion (see  FIG. 1B ) where the two display panels  40   a  and  40   b  described in Embodiment 1 overlap with each other. 
     In  FIG. 10 , the display panel positioned on the upper side (the display surface side) includes the transparent portion  810  adjacent to the display portion  804 . Furthermore, the display portion  804  of the lower display panel and the transparent portion  810  of the upper display panel overlap each other. Thus, a non-display region between the display regions of the two overlapping display panels can be reduced and even removed. As a result, a large-sized display device in which a joint portion of the display portions is hardly seen by the user can be obtained. 
     In  FIG. 10 , the adhesive layer  723  transmitting visible light is provided between the display portion  804  of the lower display panel and the transparent portion  810  of the upper display panel. The difference in refractive index between the adhesive layer  723  and the substrate  701  of the upper display panel and/or the substrate  711  of the lower display panel is preferably small. Such a structure can reduce reflection by the interface due to the difference in refractive index in a stack located over the display portion  804  of the lower display panel. In addition, display unevenness or luminance unevenness of a large display device can be suppressed. 
     [Structure Example 2] 
       FIG. 9A  is a plan view of the display panel, and  FIG. 11A  is an example of a cross-sectional view taken along the dashed-dotted line A 1 -A 2  in  FIG. 9A . The display panel in Structure Example 2 is a top-emission display panel using a color filter method, which differs from the display panel in Structure Example 1. Here, only different points from those of Structure Example 1 are described and the description of the same points as Structure Example 1 is omitted. 
     A display panel which can be used in a display device of one embodiment of the present invention is a display panel in which a plurality of pixels and a plurality of auxiliary electrodes are provided in a display portion, each pixel includes a light-emitting element and a transistor, the light-emitting element includes a lower electrode, an upper electrode, and an EL layer between the lower electrode and the upper electrode, and the auxiliary electrode is in contact with the upper electrode between adjacent lower electrodes. 
     A display panel shown in  FIG. 11A  has a structure in which subpixels of four colors of R, G, B, and Y express one color.  FIG. 11C  shows an example of the arrangement of the subpixels of R, G, B, and Y. The cross-sectional view of the display portion  804  in  FIG. 11A  is taken along the dashed-dotted line Z 1 -Z 2  in  FIG. 11C . 
     As in the display panel shown in  FIG. 11A , the light-emitting element  830  includes an optical adjustment layer  832  between the lower electrode  831  and the EL layer  833 . A light-transmitting conductive material is preferably used for the optical adjustment layer  832 . Owing to the combination of the coloring layer and a microcavity structure utilizing the optical adjustment layer, light with high color purity can be extracted from the display device of one embodiment of the present invention. The thickness of the optical adjustment layer may be varied depending on the color of the sub-pixel. In  FIG. 11A , an optical adjustment layer  832 R of the subpixel R and an optical adjustment layer  832 B of the subpixel B are shown. 
     The display panel in  FIG. 11A  includes a spacer  823  over the insulating layer  821 . The spacer  823  can adjust the distance between the substrate  701  and the substrate  711 . 
     The display panel in  FIG. 11A  includes an overcoat  849  covering the coloring layer  845  and the light-blocking layer  847 . The space between the light-emitting element  830  and the overcoat  849  is filled with the adhesive layer  822 . 
     In the display panel that can be used in the display device of one embodiment of the present invention, the transparent portion is adjacent to the display portion and provided along the sides of the display portion. In particular, in the case where the size of the display panel is large, it is required that a region not overlapping with the transparent portion include a contact region where an upper electrode (in this embodiment, the upper electrode  835 ) common to pixels in the display portion is connected to a wiring in the vicinity of the display portion supplied with a power supply voltage. In the case where a conductive layer forming the upper electrode has high electric resistance, there is a concern that luminance of light emitted from a pixel apart from the contact region in the display portion be lowered by a voltage drop of the upper electrode. 
     The display panel shown in  FIG. 11A  includes, between pixels, an auxiliary electrode  860  for suppressing the voltage drop of the upper electrode  835 . The auxiliary electrode  860  is preferably formed of conductive materials whose electric resistance is lower than that of the upper electrode  835 . 
     The conductive layer forming the auxiliary electrode  860 , the lower electrode  831 , and the like are preferably formed at the same time because a process can be shortened. In  FIG. 11A , the auxiliary electrode  860  is formed of a conductive material of the lower electrode  831  and a conductive material of the optical adjustment layer  832 . 
     Here, a method of forming the auxiliary electrode  860  will be described.  FIGS. 11B and 11C  show examples of a top view of sub-pixels R, G, B, and Y in the display portion  804 .  FIG. 11B  is a top view at the time of finishing the formation of the lower electrode  831 .  FIG. 11C  is a top view at the time of finishing the formation of the optical adjustment layer  832 , the insulating layer  821 , and the spacer  823  after the state shown in  FIG. 11B . Note that components such as the transistor  820  which are formed before the formation of the lower electrode  831  are not shown in  FIGS. 11B and 11C . 
     The auxiliary electrode  860  can be provided so as to fill a space between sub-pixels. For example, the auxiliary electrode  860  may be provided in a net-like shape so as to surround the lower electrode  831  in each sub-pixel, or may be provided in a plurality of lines (or stripes) in a space in one direction between adjacent lower electrodes  831 . 
     The auxiliary electrode  860  forming one line is preferably continuous because the electric resistance of the upper electrode  835  can be further reduced.  FIG. 11B  shows an example in which a conductive layer  860   a  is provided in a line. Note that here, the conductive layer  860   a  is formed of the conductive layer used for forming the lower electrode  831 . 
     The auxiliary electrode  860  is in contact with the upper electrode  835  so as to be electrically connected to the upper electrode  835 . Therefore, in the case where EL layers  833  are formed by a separate coloring method, the EL layers  833  are not formed over the auxiliary electrode  860 , and the upper electrode  835  is formed over the auxiliary electrode  860 , whereby the auxiliary electrode  860  and the upper electrode  835  can be in contact with each other. 
     In this embodiment, the EL layers  833  are formed also on the auxiliary electrode  860  because the EL layers  833  are formed without using a separate coloring method. Therefore, a method for forming the upper electrode  835  so that a part of a surface of the auxiliary electrode  860  is not covered with the EL layer  833  and the part is covered with the upper electrode  835  is required. 
     FIG.  11 D 1  is an enlarged view of the auxiliary electrode  860 . The auxiliary electrode  860  has a stacked-layer structure of the conductive layer  860   a  and a conductive layer  860   b . In the structure, the area of a bottom surface of the conductive layer  860   b  is larger than the area of a top surface of the conductive layer  860   a , and a part of the conductive layer  860   b  extends beyond the conductive layer  860   a.    
     When the auxiliary electrode  860  has such a structure, the conductive layer  860   b  serves as eaves in forming the EL layer  833 . Therefore, the EL layer  833  is not formed on a part of a side surface of the conductive layer  860   a , so that the part of the side surface can be exposed. Furthermore, the upper electrode  835  is formed by a formation method which has lower anisotropy than a formation method for forming the EL layer  833 . Thus, the upper electrode  835  can be formed on the side surface of the conductive layer  860   a , and the conductive layer  860   a  and the upper electrode  835  can be in contact with each other. 
     Note that in a process of manufacturing the display panel, a film lower than the conductive layer  860   a  might be etched in etching the conductive layer  860   a  or the conductive layer  860   b . In the case where a region in contact with an end portion of a lower surface of the conductive layer  860   a  is etched in the film, the EL layer  833  is less likely to be formed on the side surface of the conductive layer  860   a  in forming the EL layer  833 . 
     FIG.  11 D 2  is a cross-sectional view of the auxiliary electrode  860  in the case where a part of an insulating layer  817   b  in contact with the end portion of the lower surface of the conductive layer  860   a  is etched. In this case, the voltage drop of the upper electrode  835  can be suppressed more effectively than in the case of FIG.  11 D 1 . 
     In  FIG. 11C , a portion which is surrounded by a dashed line and is not hatched is covered with the insulating layer  821 . In other words, regions surrounded by a solid line except the spacer  823  (a part of the optical adjustment layer  832  and a part of the conductive layer  860   b ) coincide with opening portions formed in the insulating layer  821 . Here, the conductive layer  860   b  and the optical adjustment layer  832  are formed of the same conductive layer. 
     In  FIG. 11C , the opening portion is formed in the insulating layer  821  so that a part of the auxiliary electrode  860  between a plurality of lower electrodes  831  is exposed. The size of the opening portion can be adjusted as appropriate depending on the electric resistance of the upper electrode  835  and the area of the display portion  804 . The width of the auxiliary electrode  860 , i.e., the length in a direction in which pixels are adjacent to each other with the auxiliary electrode  860  provided therebetween can be adjusted as appropriate depending on the electric resistance of the upper electrode  835  and the area of the display portion  804 . 
     Described below is a method for checking whether the auxiliary electrode  860  in the display panel performs its function, i.e., whether the side surface of the auxiliary electrode  860  is in contact with the upper electrode  835  as shown in FIG.  11 D 1  or FIG.  11 D 2 . 
     In the display portion  804 , a wiring (hereinafter referred to as a measurement wiring) electrically connected to the auxiliary electrodes  860  extending in one direction in a stripe is connected to one terminal (hereinafter referred to as a terminal A) included in the FPC  808 . One terminal included in the FPC  808  electrically connected to the upper electrode  835  is referred to as a terminal B. 
     When an electric resistance value between the terminal A and the terminal B is greater than or equal to 100Ω and less than or equal to 10 kΩ, the auxiliary electrode  860  can be regarded as being in contact with the upper electrode  835  in the display portion  804 . Note that the lower limit of the electric resistance value may vary depending on the materials of the auxiliary electrode  860 , the material of the upper electrode  835 , and a material and a length of the measurement wiring. 
     Correction circuits may be provided in pixels to suppress variation in current flowing in the light-emitting elements  830  in the pixels. Specifically, a plurality of transistors and/or a plurality of capacitors may be provided in each sub-pixel so that variation in current flowing in the transistors  820  each having a source electrode or a drain electrode connected to the lower electrode  831  through a conductive layer  856  is suppressed in different sub-pixels of the same color. The variation in current is due to variation in the thickness of a semiconductor layer of the transistor  820  in some cases. For example, a transistor  870  and a capacitor  871  shown in  FIG. 11A  may have a function of correcting variation in current flowing in the transistor  820 . 
       FIG. 12 ,  FIGS. 13A and 13B ,  FIGS. 14A and 14B ,  FIGS. 15A and 15B , and  FIGS. 16A and 16B  show examples of a pixel circuit including the above-described correction circuit. 
     A pixel circuit shown in  FIG. 12  includes six transistors (transistors M 1  to M 6 ), three capacitors (capacitors C 1  to C 3 ), and the light-emitting element  830 . A wiring S 1 , a wiring S 2 , and wirings G 1  to G 6  are electrically connected to the pixel circuit shown in  FIG. 12 . Note that as the transistors M 1  to M 6 , for example, n-channel transistors can be used. 
     For example, the wirings G 1  to G 4  shown in  FIG. 12  are electrically connected to the scan line driver circuit in the operating circuit portion  806 . For example, the wiring S 1  shown in  FIG. 12  is electrically connected to the signal line driver circuit in the operating circuit portion  806 . For example, the wiring G 5 , the wiring G 6 , and the wiring S 2  shown in  FIG. 12  are electrically connected to a constant voltage source. 
     For example, the transistor  820  in  FIG. 11A  can serve as the transistor M 6 . For example, the transistor  870  in  FIG. 11A  can serve as any one of the transistors M 1  to M 5 . For example, the capacitor  871  in  FIG. 11A  can serve as any one of the capacitors C 1  to C 3 . 
     A pixel circuit shown in  FIG. 13A  includes six transistors (M 7  to M 12 ), a capacitor C 4 , and the light-emitting element  830 . The pixel circuit shown in  FIG. 13A  is electrically connected to wirings S 3  and S 4  and wirings G 7  to G 11 . Note that as the transistors M 7  to M 12 , for example, n-channel transistors can be used. Alternatively, p-channel transistors (M 13  to M 18 ) may be used instead of the transistors M 7  to M 12 , as shown in  FIG. 13B . 
     A pixel circuit shown in  FIG. 14A  has a structure in which a transistor M 19  is added to the pixel circuit shown in  FIG. 13A . The pixel circuit shown in  FIG. 14A  is electrically connected to wirings G 12  and G 13 . The wirings G 11  and G 12  may be electrically connected to each other. Note that as the transistor M 19 , for example, an n-channel transistor can be used. 
     A pixel circuit shown in  FIG. 14B  has a structure in which a transistor M 20  is added to the pixel circuit shown in  FIG. 13B . The pixel circuit shown in  FIG. 14B  is electrically connected to the wirings G 12  and G 13 . The wirings G 11  and G 12  may be electrically connected to each other. Note that as the transistor M 20 , for example, a p-channel transistor can be used. 
     A pixel circuit shown in  FIG. 15A  includes six transistors (M 21  to M 26 ), the capacitor C 4 , and the light-emitting element  830 . The pixel circuit shown in  FIG. 15A  is electrically connected to wirings S 5  to S 7  and wirings G 14  to G 16 . The wirings G 14  to G 16  may be electrically connected to each other. Note that as the transistors M 21  to M 26 , for example, n-channel transistors can be used. Alternatively, p-channel transistors (M 27  to M 32 ) may be used instead of the transistors M 21  to M 26 , as shown in  FIG. 15B . 
     A pixel circuit shown in  FIG. 16A  includes two transistors (transistors M 33  and M 34 ), two capacitors (capacitors C 5  and C 6 ), and the light-emitting element  830 . The pixel circuit shown in  FIG. 16A  is electrically connected to wirings S 8  to S 9  and wirings G 17  to G 19 . With the configuration of the pixel circuit shown in  FIG. 16A , the pixel circuit shown in  FIG. 16A  can be driven by a voltage inputting current driving method (also referred to as CVCC). Note that as the transistors M 33  and M 34 , for example, n-channel transistors can be used. Alternatively, p-channel transistors (M 35  and M 36 ) may be used instead of the transistors M 33  to M 34 , as shown in  FIG. 16B . 
     [Structure Example 3] 
       FIG. 9B  is a plan view of the display panel, and  FIG. 17A  is an example of a cross-sectional view taken along the dashed-dotted line A 3 -A 4  in  FIG. 9B . The display panel in Structure Example 3 is a top-emission display device using a separate coloring method. 
     The display panel in  FIG. 17A  includes the substrate  701 , the adhesive layer  703 , the insulating layer  705 , a plurality of transistors, the conductive layer  857 , the insulating layer  815 , the insulating layer  817 , a plurality of light-emitting elements, the insulating layer  821 , the spacer  823 , the adhesive layer  822 , the insulating layer  715 , and the substrate  711 . The adhesive layer  822 , the insulating layer  715 , and the substrate  711  transmit visible light. 
     In the display panel in  FIG. 17A , the connector  825  is positioned over the insulating layer  815 . The connector  825  is connected to the conductive layer  857  through an opening provided in the insulating layer  815 . Moreover, the connector  825  is connected to the FPC  808 . The FPC  808  and the conductive layer  857  are electrically connected to each other with the connector  825  provided therebetween. 
     [Structure Example 4] 
       FIG. 9B  is a plan view of the display panel, and  FIG. 17B  is an example of a cross-sectional view taken along the dashed-dotted line A 3 -A 4  in  FIG. 9B . The display panel in Structure Example 4 is a bottom-emission display panel using a color filter method. 
     The display panel in  FIG. 17B  includes the substrate  701 , the adhesive layer  703 , the insulating layer  705 , a plurality of transistors, the conductive layer  857 , the insulating layer  815 , the coloring layer  845 , the insulating layer  817   a , the insulating layer  817   b , the conductive layer  856 , a plurality of light-emitting elements, the insulating layer  821 , the adhesive layer  822 , and the substrate  711 . The substrate  701 , the adhesive layer  703 , the insulating layer  705 , the insulating layer  815 , the insulating layer  817   a , and the insulating layer  817   b  transmit visible light. 
     The display portion  804  includes the transistor  820 , the transistor  824 , and the light-emitting element  830  over the insulating layer  705 . The light-emitting element  830  includes the lower electrode  831  over the insulating layer  817   b , the EL layer  833  over the lower electrode  831 , and the upper electrode  835  over the EL layer  833 . The lower electrode  831  is electrically connected to a source electrode or a drain electrode of the transistor  820 . An end portion of the lower electrode  831  is covered with the insulating layer  821 . The upper electrode  835  preferably reflects visible light. The lower electrode  831  transmits visible light. The coloring layer  845  that overlaps with the light-emitting element  830  can be provided anywhere; for example, the coloring layer  845  may be provided between the insulating layers  817   a  and  817   b  or between the insulating layers  815  and  817   a.    
     In the operating circuit portion  806 , a plurality of transistors are provided over the substrate  701  with the adhesive layer  703  and the insulating layer  705  provided therebetween. In  FIG. 17B , two of the transistors included in the operating circuit portion  806  is illustrated. 
     The insulating layer  705  is preferably highly resistant to moisture, in which case impurities such as water can be prevented from entering the light-emitting element  830 , the transistor  820 , or the transistor  824 , leading to higher reliability of the display panel. 
     The conductive layer  857  is electrically connected to an external electrode through which a signal or a potential from the outside is transmitted to the operating circuit portion  806 . Here, an example in which the FPC  808  is provided as the external electrode is described. Here, an example is described in which the conductive layer  857  is formed using the same material and the same step(s) as those of the conductive layer  856 . 
     [Examples of Materials and Formation Method] 
     Next, materials and the like that can be used for the display panel or the light-emitting panel are described. Note that description of the components already described in this specification and the like is omitted in some cases. 
     For each of the substrates, a material such as glass, quartz, an organic resin, a metal, or an alloy can be used. The substrate through which light is extracted from the light-emitting element is formed using a material which transmits the light. 
     In particular, a flexible substrate is preferably used. For example, an organic resin; or glass, a metal, or an alloy that is thin enough to have flexibility can be used. 
     An organic resin, which has a specific gravity smaller than that of glass, is preferably used for the flexible substrate, in which case the display panel can be lightweight as compared with the case where glass is used. 
     The substrate is preferably formed using a material with high toughness. In that case, a display panel with high impact resistance that is less likely to be broken can be provided. For example, when an organic resin substrate or a thin metal or alloy substrate is used, the display panel can be lightweight and unlikely to be broken as compared with the case where a glass substrate is used. 
     A metal material and an alloy material, which have high thermal conductivity, are preferable because they can easily conduct heat to the whole substrate and accordingly can prevent a local temperature rise in the display panel. The thickness of a substrate using a metal material or an alloy material is preferably greater than or equal to 10 μm and less than or equal to 200 μm, further preferably greater than or equal to 20 μm and less than or equal to 50 μm. 
     There is no particular limitation on a material of the metal substrate or the alloy substrate, but it is preferable to use, for example, aluminum, copper, nickel, or a metal alloy such as an aluminum alloy or stainless steel. 
     Furthermore, when a material with high thermal emissivity is used for the substrate, the surface temperature of the display panel can be prevented from rising, leading to inhibition of breakage or a decrease in reliability of the display panel. For example, the substrate may have a stacked-layer structure of a metal substrate and a layer with high thermal emissivity (the layer can be formed using a metal oxide or a ceramic material, for example). 
     As the substrate having flexibility and a light-transmitting property, a plastic substrate that is formed as a film, for example, a plastic substrate made from polyimide (PI), an aramid, polyethylene terephthalate (PET), polyethersulfone (PES), polyethylene naphthalate (PEN), polycarbonate (PC), nylon, polyetheretherketone (PEEK), polysulfone (PSF), polyetherimide (PEI), polyarylate (PAR), polybutylene terephthalate (PBT), a silicone resin, and the like, or a glass substrate can be used. The substrate may include a fiber or the like (e.g., a prepreg). Furthermore, the substrate is not limited to the resin film, and a transparent nonwoven fabric formed by processing pulp into a continuous sheet, a sheet including an artificial spider&#39;s thread fiber containing protein called fibroin, a complex in which the transparent nonwoven fabric or the sheet and a resin are mixed, a stack of a resin film and a nonwoven fabric containing a cellulose fiber whose fiber width is 4 nm or more and 100 nm or less, or a stack of a resin film and a sheet including an artificial spider&#39;s thread fiber may be used. 
     The flexible substrate may have a stacked-layer structure in which a hard coat layer (e.g., a silicon nitride layer) by which a surface of the device is protected from damage, a layer which can disperse pressure (e.g., an aramid resin layer), or the like is stacked over a layer of any of the above-mentioned materials. 
     The flexible substrate may be formed by stacking a plurality of layers. When a glass layer is used, a barrier property against water and oxygen can be improved and thus a highly reliable display panel can be provided. 
     For example, a flexible substrate in which a glass layer, an adhesive layer, and an organic resin layer are stacked from the side closer to a light-emitting element can be used. The thickness of the glass layer is greater than or equal to 20 μm and less than or equal to 200 μm, preferably greater than or equal to 25 μm and less than or equal to 100 μm. With such a thickness, the glass layer can have both a high barrier property against water and oxygen and high flexibility. The thickness of the organic resin layer is greater than or equal to 10 μm and less than or equal to 200 μm, preferably greater than or equal to 20 μm and less than or equal to 50 μm. By providing such an organic resin layer outside the glass layer, occurrence of a crack or a break in the glass layer can be inhibited and mechanical strength can be improved. With the substrate that includes such a composite material of a glass material and an organic resin, a highly reliable flexible display panel can be provided. 
     Here, a method for forming a flexible display panel is described. 
     For convenience, a structure including a pixel and a driver circuit, a structure including an optical member such as a color filter, a structure including a touch sensor, or a structure including a functional member is referred to as an element layer. An element layer includes a display element, for example, and may include a wiring electrically connected to a display element or an element such as a transistor used in a pixel or a circuit in addition to the display element. 
     Here, a support provided with an insulating surface over which an element layer is formed is called a base material. 
     As a method for forming an element layer over a flexible base material, there are a method in which an element layer is formed directly over a base material, and a method in which an element layer is formed over a supporting base material that is different from the base material and has stiffness and then the element layer is separated from the supporting base material and transferred to the base material. 
     In the case where a material of the base material can withstand heating temperature in the process for forming the element layer, it is preferred that the element layer be formed directly over the base material, in which case a manufacturing process can be simplified. At this time, the element layer is preferably formed in a state where the base material is fixed to the supporting base material, in which case the transfer of the element layer in a device and between devices can be easy. 
     In the case of employing the method in which the element layer is formed over the supporting base material and then transferred to the base material, first, a separation layer and an insulating layer are stacked over a supporting base material, and then the element layer is formed over the insulating layer. Then, the element layer is separated from the supporting base material and then transferred to the base material. At this time, a material is selected such that separation at an interface between the supporting base material and the separation layer, at an interface between the separation layer and the insulating layer, or in the separation layer occurs. With such a method, the element layer can be formed at temperatures higher than the upper temperature limit of the base material, which improves the reliability of the display panel. 
     For example, it is preferable that stacked layers of a layer including a high-melting-point metal material, such as tungsten, and a layer including an oxide of the metal material be used as the separation layer, and stacked layers of a plurality of layers as the insulating layer, such as a silicon nitride layer and a silicon oxynitride layer be used over the separation layer. By using a high-melting-point metal material, a high-temperature process can be performed to form the element layer, resulting in high reliability. For example, impurities contained in the element layer can be further reduced, and the crystallinity of a semiconductor or the like included in the element layer can be further increased. For the base material, any of the above flexible materials can be preferably used. 
     Examples of the separation include peeling off by application of mechanical power, removal of the separation layer by etching, or separation by dripping of a liquid into part of the separation interface to penetrate the entire separation interface. 
     The separation layer is not necessarily provided in the case where separation can occur at an interface between the supporting base material and the insulating layer. For example, glass may be used as the supporting base material, an organic resin such as polyimide may be used as the insulating layer, a separation trigger may be formed by locally heating part of the organic resin by laser light or the like, and separation may be performed at an interface between the glass and the insulating layer. Alternatively, it is possible that a layer containing a material with high thermal conductivity (e.g., a metal or a semiconductor) is provided between the supporting base material and the insulating layer containing an organic resin, and this layer is heated by current so that separation easily occurs, and then separation is performed. In this case, the insulating layer containing an organic resin can also be used as the base material. 
     As the adhesive layer, a variety of curable resins such as a reactive curable resin, a thermosetting resin, an anaerobic resin, and a photo curable resin such as an ultraviolet curable resin can be used. Examples of such resins include an epoxy resin, an acrylic resin, a silicone resin, a phenol resin, a polyimide resin, an imide resin, a polyvinyl chloride (PVC) resin, a polyvinyl butyral (PVB) resin, an ethylene vinyl acetate (EVA) resin, and the like. In particular, a material with low moisture permeability, such as an epoxy resin, is preferable. Alternatively, a two-component-mixture-type resin may be used. Further alternatively, an adhesive sheet or the like may be used. 
     Furthermore, the resin may include a drying agent. For example, a substance which adsorbs moisture by chemical adsorption, such as an oxide of an alkaline earth metal (e.g., calcium oxide or barium oxide), can be used. Alternatively, a substance that adsorbs moisture by physical adsorption, such as zeolite or silica gel, may be used. The drying agent is preferably included, in which case entry of impurities such as moisture into the light-emitting element can be inhibited and the reliability of the display panel can be improved. 
     In addition, a filler with a high refractive index or a light scattering member is mixed into the resin, in which case the efficiency of light extraction from the light-emitting element can be improved. For example, titanium oxide, barium oxide, zeolite, zirconium, or the like can be used. 
     Insulating films with high resistance to moisture are preferably used for the insulating layer  705  and the insulating layer  715 . Alternatively, the insulating layer  705  and the insulating layer  715  preferably have a function of preventing diffusion of impurities to a light-emitting element. 
     As an insulating film having an excellent moisture-proof property, a film containing nitrogen and silicon (e.g., a silicon nitride film or a silicon nitride oxide film), a film containing nitrogen and aluminum (e.g., an aluminum nitride film), or the like can be used. Alternatively, a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, or the like can be used. 
     For example, the water vapor transmittance of the insulating film having an excellent moisture-proof property is lower than or equal to 1×10 −5  [g/(m 2 ·day)], preferably lower than or equal to 1×10 −6  [g/(m 2 ·day)], further preferably lower than or equal to 1×10 −7  [g/(m 2 ·day)], still further preferably lower than or equal to 1×10 −8  [g/(m 2 ·day)]. 
     In the display panel, it is necessary that at least one of the insulating layers  705  and  715 , which is on the light-emitting surface side, transmit light emitted from the light-emitting element. In the case where the display panel includes the insulating layers  705  and  715 , one of the insulating layers  705  and  715 , which transmits light emitted from the light-emitting element, preferably has higher average transmittance than the other in a wavelength of 400 nm or more and 800 nm or less. 
     The insulating layers  705  and  715  each preferably include oxygen, nitrogen, and silicon. The insulating layers  705  and  715  each preferably include, for example, silicon oxynitride. Moreover, the insulating layers  705  and  715  each preferably include silicon nitride or silicon nitride oxide. It is preferable that the insulating layers  705  and  715  be each formed using a silicon oxynitride film and a silicon nitride film, which are in contact with each other. The silicon oxynitride film and the silicon nitride film are alternately stacked so that antiphase interference occurs more often in a visible region, whereby the stack can have higher transmittance of light in the visible region. 
     There is no particular limitation on the structure of the transistor in the display panel. For example, a forward staggered transistor or an inverted staggered transistor may be used. Furthermore, a top-gate transistor or a bottom-gate transistor may be used. A semiconductor material used for the transistors is not particularly limited, and for example, silicon, germanium, or an organic semiconductor can be used. Alternatively, an oxide semiconductor containing at least one of indium, gallium, and zinc, such as an In—Ga—Zn-based metal oxide, may be used. 
     There is no particular limitation on the crystallinity of a semiconductor material used for the transistors, and an amorphous semiconductor or a semiconductor having crystallinity (a microcrystalline semiconductor, a polycrystalline semiconductor, a single-crystal semiconductor, or a semiconductor partly including crystal regions) may be used. It is preferable that a semiconductor having crystallinity be used, in which case deterioration of the transistor characteristics can be inhibited. 
     For stable characteristics of the transistor, a base film is preferably provided. The base film can be formed to have a single-layer structure or a stacked-layer structure using an inorganic insulating film such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a silicon nitride oxide film. The base film can be formed by a sputtering method, a chemical vapor deposition (CVD) method (e.g., a plasma CVD method, a thermal CVD method, or a metal organic CVD (MOCVD) method), an atomic layer deposition (ALD) method, a coating method, a printing method, or the like. Note that the base film is not necessarily provided. In each of the above structure examples, the insulating layer  705  can serve as a base film of the transistor. 
     As the light-emitting element, a self-luminous element can be used, and an element whose luminance is controlled by current or voltage is included in the category of the light-emitting element. For example, a light-emitting diode (LED), an organic EL element, an inorganic EL element, or the like can be used. 
     The light-emitting element may have any of a top emission structure, a bottom emission structure, and a dual emission structure. A conductive film that transmits visible light is used as the electrode through which light is extracted. A conductive film that reflects visible light is preferably used as the electrode through which light is not extracted. 
     The conductive film that transmits visible light can be formed using, for example, indium oxide, indium tin oxide (ITO), indium zinc oxide, zinc oxide (ZnO), or zinc oxide to which gallium is added. Alternatively, a film of a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or titanium; an alloy containing any of these metal materials; a nitride of any of these metal materials (e.g., titanium nitride); or the like can be formed thin so as to transmit light. Alternatively, a stacked film of any of the above materials can be used as the conductive layer. For example, a stacked film of ITO and an alloy of silver and magnesium is preferably used, in which case conductivity can be increased. Further alternatively, graphene or the like may be used. 
     For the conductive film that reflects visible light, for example, a metal material, such as aluminum, gold, platinum, silver, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, or palladium or an alloy including any of these metal materials can be used. Lanthanum, neodymium, germanium, or the like may be added to the metal material or the alloy. Furthermore, an alloy containing aluminum (an aluminum alloy) such as an alloy of aluminum and titanium, an alloy of aluminum and nickel, an alloy of aluminum and neodymium, or an alloy of aluminum, nickel, and lanthanum (Al—Ni—La), or an alloy containing silver such as an alloy of silver and copper, an alloy of silver, palladium, and copper (Ag—Pd—Cu, also referred to as APC), or an alloy of silver and magnesium can be used for the conductive film. An alloy of silver and copper is preferable because of its high heat resistance. Moreover, a metal film or a metal oxide film is stacked on an aluminum alloy film, whereby oxidation of the aluminum alloy film can be suppressed. Examples of a material for the metal film or the metal oxide film are titanium and titanium oxide. Alternatively, the conductive film having a property of transmitting visible light and a film containing any of the above metal materials may be stacked. For example, a stacked film of silver and ITO or a stacked film of an alloy of silver and magnesium and ITO can be used. 
     The lower electrode  831 , the upper electrode  835 , and the conductive layers forming the auxiliary electrode  860  (the conductive layers  860   a  and  860   b ) can be formed of the conductive film that transmits visible light or the conductive film that reflects visible light. 
     The electrodes may be formed separately by an evaporation method or a sputtering method. Alternatively, a discharging method such as an ink-jet method, a printing method such as a screen printing method, or a plating method may be used. 
     When a voltage higher than the threshold voltage of the light-emitting element is applied between the lower electrode  831  and the upper electrode  835 , holes are injected to the EL layer  833  from the anode side and electrons are injected to the EL layer  833  from the cathode side. The injected electrons and holes are recombined in the EL layer  833  and a light-emitting substance contained in the EL layer  833  emits light. 
     The EL layer  833  includes at least a light-emitting layer. In addition to the light-emitting layer, the EL layer  833  may further include one or more layers containing any of a substance with a high hole-injection property, a substance with a high hole-transport property, a hole-blocking material, a substance with a high electron-transport property, a substance with a high electron-injection property, a substance with a bipolar property (a substance with a high electron- and hole-transport property), and the like. 
     For the EL layer  833 , either a low molecular compound or a high molecular compound can be used, and an inorganic compound may also be used. Each of the layers included in the EL layer  833  can be formed by any of the following methods: an evaporation method (including a vacuum evaporation method), a transfer method, a printing method, an inkjet method, a coating method, and the like. 
     The light-emitting element  830  may contain two or more kinds of light-emitting substances. Thus, for example, a light-emitting element that emits white light can be achieved. For example, a white emission can be obtained by selecting light-emitting substances so that two or more kinds of light-emitting substances emit light of complementary colors. A light-emitting substance that emits red (R) light, green (G) light, blue (B) light, yellow (Y) light, or orange (O) light or a light-emitting substance that emits light containing spectral components of two or more of R light, G light, and B light can be used, for example. A light-emitting substance that emits blue light and a light-emitting substance that emits yellow light may be used, for example. At this time, the emission spectrum of the light-emitting substance that emits yellow light preferably contains spectral components of G light and R light. The emission spectrum of the light-emitting element  830  preferably has two or more peaks in the wavelength range in a visible region (e.g., greater than or equal to 350 nm and less than or equal to 750 nm or greater than or equal to 400 nm and less than or equal to 800 nm). 
     The EL layer  833  may include a plurality of light-emitting layers. In the EL layer  833 , the plurality of light-emitting layers may be stacked in contact with one another or may be stacked with a separation layer provided therebetween. The separation layer may be provided between a fluorescent layer and a phosphorescent layer, for example. 
     The separation layer can be provided, for example, to prevent energy transfer by the Dexter mechanism (particularly triplet energy transfer) from a phosphorescent material or the like in an excited state which is generated in the phosphorescent layer to a fluorescent material or the like in the fluorescent layer. The thickness of the separation layer may be several nanometers. Specifically, the thickness of the separation layer may be greater than or equal to 0.1 nm and less than or equal to 20 nm, greater than or equal to 1 nm and less than or equal to 10 nm, or greater than or equal to 1 nm and less than or equal to 5 nm. The separation layer contains a single material (preferably, a bipolar substance) or a plurality of materials (preferably, a hole-transport material and an electron-transport material). 
     The separation layer may be formed using a material contained in a light-emitting layer in contact with the separation layer. This facilitates the manufacture of the light-emitting element and reduces the drive voltage. For example, in the case where the phosphorescent layer includes a host material, an assist material, and a phosphorescent material (guest material), the separation layer may be formed using the host material and the assist material. In other words, the separation layer includes a region not containing the phosphorescent material and the phosphorescent layer includes a region containing the phosphorescent material in the above structure. Accordingly, the separation layer and the phosphorescent layer can be evaporated separately depending on whether a phosphorescent material is used or not. With such a structure, the separation layer and the phosphorescent layer can be formed in the same chamber. Thus, the manufacturing costs can be reduced. 
     Moreover, the light-emitting element  830  may be a single element including one EL layer or a tandem element in which EL layers are stacked with a charge generation layer provided therebetween. 
     The light-emitting element is preferably provided between a pair of insulating films having an excellent moisture-proof property. In that case, entry of an impurity such as moisture into the light-emitting element can be inhibited, leading to inhibition of a decrease in the reliability of the display panel. 
     As the insulating layer  815  and the insulating layer  816 , for example, an inorganic insulating film such as a silicon oxide film, a silicon oxynitride film, or an aluminum oxide film can be used. Note that the insulating layer  815  and the insulating layer  816  may be formed using different materials. As the insulating layer  817 , the insulating layer  817   a , and the insulating layer  817   b , an organic material such as polyimide, acrylic, polyamide, polyimide amide, or a benzocyclobutene-based resin can be used, for example. Alternatively, a low-dielectric constant material (a low-k material) or the like can be used. Furthermore, each insulating layer may be formed by stacking a plurality of insulating films. 
     The insulating layer  821  is formed using an organic insulating material or an inorganic insulating material. As the resin, for example, a polyimide resin, a polyamide resin, an acrylic resin, a siloxane resin, an epoxy resin, or a phenol resin can be used. It is particularly preferable that the insulating layer  821  be formed using a photosensitive resin material to have an opening portion over the lower electrode  831  so that a side wall of the opening portion is formed as an inclined surface with a continuous curvature. 
     There is no particular limitation on the method for forming the insulating layer  821 ; a photolithography method, a sputtering method, an evaporation method, a droplet discharging method (e.g., an inkjet method), a printing method (e.g., a screen printing method or an off-set printing method), or the like may be used. 
     The spacer  823  can be formed using an inorganic insulating material, an organic insulating material, a metal material, or the like. As the inorganic insulating material and the organic insulating material, for example, a variety of materials that can be used for the insulating layer can be used. As the metal material, titanium, aluminum, or the like can be used. When the spacer  823  containing a conductive material is electrically connected to the upper electrode  835 , a potential drop due to the resistance of the upper electrode  835  can be inhibited. The spacer  823  may have either a tapered shape or an inverse tapered shape. 
     For example, a conductive layer functioning as an electrode or a wiring of the transistor, an auxiliary electrode of the light-emitting element, or the like, which is used for the display panel, can be formed to have a single-layer structure or a stacked-layer structure using any of metal materials such as molybdenum, titanium, chromium, tantalum, tungsten, aluminum, copper, neodymium, and scandium, and an alloy material containing any of these elements. Alternatively, the conductive layer may be formed using a conductive metal oxide. As the conductive metal oxide, indium oxide (e.g., In 2 O 3 ), tin oxide (e.g., SnO 2 ), ZnO, ITO, indium zinc oxide (e.g., In 2 O 3 —ZnO), or any of these metal oxide materials in which silicon oxide is contained can be used. 
     The coloring layer is a colored layer that transmits light in a specific wavelength range. For example, a color filter for transmitting light in a red, green, blue, or yellow wavelength range can be used. Each coloring layer is formed in a desired position with any of various materials by a printing method, an inkjet method, an etching method using a photolithography method, or the like. In a white sub-pixel, a resin such as a transparent resin or a white resin may be provided so as to overlap with the light-emitting element. 
     The light-blocking layer is provided between the adjacent coloring layers. The light-blocking layer blocks light emitted from an adjacent light-emitting element to inhibit color mixture between adjacent light-emitting elements. Here, the coloring layer is provided such that its end portion overlaps with the light-blocking layer, whereby light leakage can be reduced. As the light-blocking layer, a material that can block light from the light-emitting element can be used; for example, a black matrix is formed using a resin material containing a metal material, pigment, or dye. Note that it is preferable to provide the light-blocking layer in a region other than the display portion, such as a driver circuit portion, in which case undesired leakage of guided light or the like can be inhibited. 
     Furthermore, an overcoat covering the coloring layer and the light-blocking layer may be provided. The overcoat can prevent an impurity and the like contained in the coloring layer from being diffused into the light-emitting element. The overcoat is formed with a material that transmits light emitted from the light-emitting element; for example, an inorganic insulating film such as a silicon nitride film or a silicon oxide film, an organic insulating film such as an acrylic film or a polyimide film can be used, and further, a stacked-layer structure of an organic insulating film and an inorganic insulating film may be employed. 
     In the case where upper surfaces of the coloring layer and the light-blocking layer are coated with a material of the adhesive layer, a material which has high wettability with respect to the material of the adhesive layer is preferably used as the material of the overcoat. For example, an oxide conductive film such as an ITO film or a metal film such as an Ag film which is thin enough to transmit light is preferably used as the overcoat. 
     As the connector, any of a variety of anisotropic conductive films (ACF), anisotropic conductive pastes (ACP), and the like can be used. 
     In this specification and the like, a display element, a display panel which is a panel including a display element, a light-emitting element, and a light-emitting panel which is a panel including a light-emitting element can employ various modes or can include various elements. A display element, a display panel, a light-emitting element, or a light-emitting panel may include a display medium whose contrast, luminance, reflectivity, transmittance, or the like is changed by electrical or magnetic effect, such as an EL element (e.g., an EL element including organic and inorganic materials, an organic EL element, or an inorganic EL element), an LED (e.g., a white LED, a red LED, a green LED, or a blue LED), a transistor (a transistor which emits light depending on current), an electron emitter, a liquid crystal element, electronic ink, an electrophoretic element, a grating light valve (GLV), a plasma display panel (PDP), a display element including micro electro mechanical systems (MEMS), a digital micromirror device (DMD), a digital micro shutter (DMS), an interferometric modulator display (IMOD) element, an MEMS shutter display element, optical interference type MEMS display element, an electrowetting element, a piezoelectric ceramic display, and a display element including a carbon nanotube. Note that examples of a display panel having an EL element include an EL display. Examples of a display panel having an electron emitter include a field emission display (FED) and an SED-type flat panel display (SED: surface-conduction electron-emitter display). Examples of a display panel having a liquid crystal element include a liquid crystal display (e.g., a transmissive liquid crystal display, a transflective liquid crystal display, a reflective liquid crystal display, a direct-view liquid crystal display, or a projection liquid crystal display). Examples of a display panel having electronic ink, ELECTRONIC LIQUID POWDER (registered trademark), or an electrophoretic element include electronic paper. In the case of a transflective liquid crystal display or a reflective liquid crystal display, some of or all of pixel electrodes function as reflective electrodes. For example, some or all of pixel electrodes are formed to contain aluminum or silver. Furthermore, in such a case, a memory circuit such as an SRAM can be provided under the reflective electrodes, leading to lower power consumption. Note that in the case of using an LED, graphene or graphite may be provided under an electrode or a nitride semiconductor of the LED. Graphene or graphite may be a multilayer film in which a plurality of layers are stacked. As described above, provision of graphene or graphite enables easy formation of a nitride semiconductor film thereover, such as an n-type GaN semiconductor layer including crystals. Furthermore, a p-type GaN semiconductor layer including crystals or the like can be provided thereover, and thus the LED can be formed. Note that an AlN layer may be provided between the n-type GaN semiconductor layer including crystals and graphene or graphite. The GaN semiconductor layers included in the LED may be formed by MOCVD. Note that when the graphene is provided, the GaN semiconductor layers included in the LED can also be formed by a sputtering method. 
     For example, in this specification and the like, an active matrix method in which an active element (a non-linear element) is included in a pixel or a passive matrix method in which an active element is not included in a pixel can be used. 
     In the active matrix method, not only a transistor but also a variety of active elements can be used. For example, an MIM (metal insulator metal), a TFD (thin film diode), or the like can also be used. Since such an element has few numbers of manufacturing steps, manufacturing cost can be reduced or yield can be improved. Alternatively, since the size of these elements is small, the aperture ratio can be improved, so that power consumption can be reduced or higher luminance can be achieved. 
     Since an active element is not used in the passive matrix method, the number of manufacturing steps can be reduced, so that manufacturing cost can be reduced or the yield can be improved. Alternatively, since an active element is not used in the passive matrix method, the aperture ratio can be improved, so that power consumption can be reduced or higher luminance can be achieved, for example. 
     Note that the light-emitting panel of one embodiment of the present invention may be used as a display panel or as a lighting panel. For example, it may be used as a light source such as a backlight or a front light, that is, a lighting panel for a display panel. 
     As described above, by using the display panel including the transparent portion described as an example in this embodiment, a large-sized display device in which a joint portion of the display portions is hardly seen and display unevenness is reduced can be obtained. 
     This embodiment can be combined with any other embodiment as appropriate. 
     [Embodiment 3] 
     In this embodiment, a touch panel that can be used in a display device of one embodiment of the present invention will be described with reference to drawings. Note that the above description can be referred to for the components of the touch panel, which are similar to those of the display panel described in Embodiment 2. Although a touch panel including a light-emitting element is described as an example in this embodiment, one embodiment of the present invention is not limited thereto. For example, a touch panel including another element (e.g., a display element), the example of which is shown in Embodiment 2, can also be used in the display device of one embodiment of the present invention. 
     [Structure Example 1] 
       FIG. 18A  is a top view of the touch panel.  FIG. 18B  is a cross-sectional view taken along the dashed-dotted line A-B and the dashed-dotted line C-D in  FIG. 18A .  FIG. 18C  is a cross-sectional view taken along the dashed-dotted line E-F in  FIG. 18A . 
     A touch panel  390  illustrated in  FIG. 18A  includes a display portion  301  (serving also as an input portion), a scan line driver circuit  303   g ( 1 ), an imaging pixel driver circuit  303   g ( 2 ), an image signal line driver circuit  303   s ( 1 ), and an imaging signal line driver circuit  303   s ( 2 ). 
     The display portion  301  includes a plurality of pixels  302  and a plurality of imaging pixels  308 . 
     The pixel  302  includes a plurality of sub-pixels. Each sub-pixel includes a light-emitting element and a pixel circuit. 
     The pixel circuits can supply electric power for driving the light-emitting element. The pixel circuits are electrically connected to wirings through which selection signals are supplied. The pixel circuits are also electrically connected to wirings through which image signals are supplied. 
     The scan line driver circuit  303   g ( 1 ) can supply selection signals to the pixels  302 . 
     The image signal line driver circuit  303   s ( 1 ) can supply image signals to the pixels  302 . 
     A touch sensor can be formed using the imaging pixels  308 . Specifically, the imaging pixels  308  can sense a touch of a finger or the like on the display portion  301 . 
     The imaging pixels  308  include photoelectric conversion elements and imaging pixel circuits. 
     The imaging pixel circuits can drive photoelectric conversion elements. The imaging pixel circuits are electrically connected to wirings through which control signals are supplied. The imaging pixel circuits are also electrically connected to wirings through which power supply potentials are supplied. 
     Examples of the control signal include a signal for selecting an imaging pixel circuit from which a recorded imaging signal is read, a signal for initializing an imaging pixel circuit, and a signal for determining the time it takes for an imaging pixel circuit to sense light. 
     The imaging pixel driver circuit  303   g ( 2 ) can supply control signals to the imaging pixels  308 . 
     The imaging signal line driver circuit  303   s ( 2 ) can read out imaging signals. 
     As illustrated in  FIGS. 18B and 18C , the touch panel  390  includes the substrate  701 , the adhesive layer  703 , the insulating layer  705 , the substrate  711 , the adhesive layer  713 , and the insulating layer  715 . The substrates  701  and  711  are bonded to each other with an adhesive layer  360 . 
     The substrate  701  and the insulating layer  705  are bonded to each other with the adhesive layer  703 . The substrate  711  and the insulating layer  715  are bonded to each other with the adhesive layer  713 . 
     The substrates  701  and  711  are preferably flexible. 
     Embodiment 2 can be referred to for materials used for the substrates, the adhesive layers, and the insulating layers. 
     Each of the pixels  302  includes the sub-pixel  302 R, a sub-pixel  302 G, and a sub-pixel  302 B (see  FIG. 18C ). The sub-pixel  302 R includes a light-emitting module  380 R, the sub-pixel  302 G includes a light-emitting module  380 G, and the sub-pixel  302 B includes a light-emitting module  380 B. 
     For example, the sub-pixel  302 R includes the light-emitting element  350 R and the pixel circuit. The pixel circuit includes a transistor  302   t  that can supply electric power to the light-emitting element  350 R. Furthermore, the light-emitting module  380 R includes the light-emitting element  350 R and an optical element (e.g., a coloring layer  367 R that transmits red light). 
     The light-emitting element  350 R includes a lower electrode  351 R, an EL layer  353 , and an upper electrode  352 , which are stacked in this order (see  FIG. 18C ). 
     The EL layer  353  includes a first EL layer  353   a , an intermediate layer  354 , and a second EL layer  353   b , which are stacked in this order. 
     Note that a microcavity structure can be provided for the light-emitting module  380 R so that light with a specific wavelength can be efficiently extracted. Specifically, an EL layer may be provided between a film that reflects visible light and a film that partly reflects and partly transmits visible light, which are provided so that light with a specific wavelength can be efficiently extracted. 
     The light-emitting module  380 R, for example, includes the adhesive layer  360  that is in contact with the light-emitting element  350 R and the coloring layer  367 R. 
     The coloring layer  367 R is positioned in a region overlapping with the light-emitting element  350 R. Accordingly, part of light emitted from the light-emitting element  350 R passes through the adhesive layer  360  and the coloring layer  367 R and is emitted to the outside of the light-emitting module  380 R as indicated by an arrow in  FIG. 18B or 18C . 
     The touch panel  390  includes a light-blocking layer  367 BM. The light-blocking layer  367 BM is provided so as to surround the coloring layer (e.g., the coloring layer  367 R). 
     The touch panel  390  includes an anti-reflective layer  367   p  positioned in a region overlapping with the display portion  301 . As the anti-reflective layer  367   p , a circular polarizing plate can be used, for example. 
     The touch panel  390  includes an insulating layer  321 . The insulating layer  321  covers the transistor  302   t  and the like. Note that the insulating layer  321  can be used as a layer for covering unevenness caused by the pixel circuits and the imaging pixel circuits. An insulating layer on which a layer that can inhibit diffusion of impurities to the transistor  302   t  and the like is stacked can be used as the insulating layer  321 . 
     The touch panel  390  includes a partition  328  that overlaps with an end portion of the lower electrode  351 R. In addition, a spacer  329  that controls the distance between the substrate  701  and the substrate  711  is provided on the partition  328 . 
     The image signal line driver circuit  303   s ( 1 ) includes a transistor  303   t  and a capacitor  303   c . Note that the driver circuit can be formed in the same process and over the same substrate as those of the pixel circuits. As illustrated in  FIG. 18B , the transistor  303   t  may include a second gate  304  over the insulating layer  321 . The second gate  304  may be electrically connected to a gate of the transistor  303   t , or different potentials may be supplied to these gates. Alternatively, if necessary, the second gate  304  may be provided for a transistor  308   t , the transistor  302   t , or the like. 
     The imaging pixels  308  each include a photoelectric conversion element  308   p  and an imaging pixel circuit. The imaging pixel circuit can sense light received by the photoelectric conversion element  308   p . The imaging pixel circuit includes the transistor  308   t.    
     For example, a PIN photodiode can be used as the photoelectric conversion element  308   p.    
     The touch panel  390  includes a wiring  311  through which a signal is supplied. The wiring  311  is provided with a terminal  319 . Note that an FPC  309  through which a signal such as an image signal or a synchronization signal is supplied is electrically connected to the terminal  319 . Note that a printed wiring board (PWB) may be attached to the FPC  309 . 
     Note that transistors such as the transistors  302   t ,  303   t , and  308   t  can be formed in the same process. Alternatively, the transistors may be formed in different processes. 
     [Structure Example 2] 
       FIGS. 19A and 19B  are perspective views of a touch panel  505 A. Note that  FIGS. 19A and 19B  illustrate only main components for simplicity.  FIG. 20A  is a cross-sectional view taken along the dashed-dotted line G-H in  FIG. 19A . 
     As illustrated in  FIGS. 19A and 19B , the touch panel  505 A includes a display portion  501 , the scan line driver circuit  303   g ( 1 ), a touch sensor  595 , and the like. Furthermore, the touch panel  505 A includes the substrate  701 , the substrate  711 , and a substrate  590 . 
     The touch panel  505 A includes a plurality of pixels and a plurality of wirings  311 . The plurality of wirings  311  can supply signals to the pixels. The plurality of wirings  311  are led to a peripheral portion of the substrate  701 , and part of the plurality of wirings  311  form the terminal  319 . The terminal  319  is electrically connected to an FPC  509 ( 1 ). 
     The touch panel  505 A includes the touch sensor  595  and a plurality of wirings  598 . The plurality of wirings  598  are electrically connected to the touch sensor  595 . The plurality of wirings  598  are led to a peripheral portion of the substrate  590 , and part of the plurality of wirings  598  form a terminal. The terminal is electrically connected to an FPC  509 ( 2 ). Note that in  FIG. 19B , electrodes, wirings, and the like of the touch sensor  595  provided on the back side of the substrate  590  (the side facing the substrate  701 ) are indicated by solid lines for clarity. 
     As the touch sensor  595 , for example, a capacitive touch sensor can be used. Examples of the capacitive touch sensor include a surface capacitive touch sensor and a projected capacitive touch sensor. An example of using a projected capacitive touch sensor is described here. 
     Examples of the projected capacitive touch sensor include a self capacitive touch sensor and a mutual capacitive touch sensor, which differ mainly in the driving method. The use of a mutual capacitive type is preferred because multiple points can be sensed simultaneously. 
     Note that a variety of sensors that can sense the closeness or the contact of a sensing target such as a finger can be used as the touch sensor  595 . 
     The projected capacitive touch sensor  595  includes electrodes  591  and electrodes  592 . The electrodes  591  are electrically connected to any of the plurality of wirings  598 , and the electrodes  592  are electrically connected to any of the other wirings  598 . 
     The electrodes  592  each have a shape of a plurality of quadrangles arranged in one direction with one corner of a quadrangle connected to one corner of another quadrangle as illustrated in  FIGS. 19A and 19B . 
     The electrodes  591  each have a quadrangular shape and are arranged in a direction intersecting with the direction in which the electrodes  592  extend. Note that the plurality of electrodes  591  is not necessarily arranged in the direction orthogonal to one electrode  592  and may be arranged to intersect with one electrode  592  at an angle of less than 90 degrees. 
     The wiring  594  intersects with the electrode  592 . The wiring  594  electrically connects two electrodes  591  between which the electrode  592  is positioned. The intersecting area of the electrode  592  and the wiring  594  is preferably as small as possible. Such a structure allows a reduction in the area of a region where the electrodes are not provided, reducing unevenness in transmittance. As a result, unevenness in luminance of light from the touch sensor  595  can be reduced. 
     Note that the shapes of the electrodes  591  and the electrodes  592  are not limited to the above-mentioned shapes and can be any of a variety of shapes. For example, the plurality of electrodes  591  may be provided so that space between the electrodes  591  are reduced as much as possible, and a plurality of electrodes  592  may be provided with an insulating layer sandwiched between the electrodes  591  and the electrodes  592  and may be spaced apart from each other to form a region not overlapping with the electrodes  591 . In that case, between two adjacent electrodes  592 , it is preferable to provide a dummy electrode which is electrically insulated from these electrodes, whereby the area of a region having a different transmittance can be reduced. 
     Note that a more specific structure example of the touch sensor  595  will be described later. 
     As illustrated in  FIG. 20A , the touch panel  505 A includes the substrate  701 , the adhesive layer  703 , the insulating layer  705 , the substrate  711 , the adhesive layer  713 , and the insulating layer  715 . The substrates  701  and  711  are bonded to each other with the adhesive layer  360 . 
     An adhesive layer  597  bonds the substrate  590  to the substrate  711  so that the touch sensor  595  overlaps with the display portion  501 . The adhesive layer  597  transmits light. 
     The electrodes  591  and the electrodes  592  are formed using a conductive material that transmits light. As a light-transmitting conductive material, a conductive oxide such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, or zinc oxide to which gallium is added can be used. Note that a film including graphene may be used as well. The film including graphene can be formed, for example, by reducing a film including graphene oxide. As a reducing method, a method with application of heat or the like can be employed. 
     The resistance of a material used for conductive films such as the electrodes  591 , the electrodes  592 , and the wiring  594 , i.e., a wiring and an electrode in the touch panel, is preferably low. Examples of the material include ITO, indium zinc oxide, ZnO, silver, copper, aluminum, a carbon nanotube, and graphene. Alternatively, a metal nanowire including a number of conductors with an extremely small width (for example, a diameter of several nanometers) may be used. Note that a metal nanowire, a carbon nanotube, graphene, or the like may be used for an electrode of the display element, e.g., a pixel electrode or a common electrode because of its high transmittance. 
     The electrodes  591  and the electrodes  592  may be formed by depositing a light-transmitting conductive material on the substrate  590  by a sputtering method and then removing an unnecessary portion by a variety of patterning technique such as photolithography. 
     The electrodes  591  and the electrodes  592  are covered with an insulating layer  593 . Furthermore, openings reaching the electrodes  591  are formed in the insulating layer  593 , and the wiring  594  electrically connects the adjacent electrodes  591 . A light-transmitting conductive material can be favorably used as the wiring  594  because the aperture ratio of the touch panel can be increased. Moreover, a material with higher conductivity than the conductivities of the electrodes  591  and the electrodes  592  can be favorably used for the wiring  594  because electric resistance can be reduced. 
     Note that an insulating layer covering the insulating layer  593  and the wiring  594  may be provided to protect the touch sensor  595 . 
     Furthermore, a connection layer  599  electrically connects the wirings  598  to the FPC  509 ( 2 ). 
     The display portion  501  includes a plurality of pixels arranged in a matrix. Each pixel has the same structure as Structure Example 1; thus, description is omitted. 
     Any of various kinds of transistors can be used in the touch panel. A structure in the case of using bottom-gate transistors is illustrated in  FIGS. 20A and 20B . 
     For example, a semiconductor layer containing an oxide semiconductor, amorphous silicon, or the like can be used in the transistor  302   t  and the transistor  303   t  illustrated in  FIG. 20A . 
     For example, a semiconductor layer containing polycrystalline silicon that is obtained by crystallization process such as laser annealing can be used in the transistor  302   t  and the transistor  303   t  illustrated in  FIG. 20B . 
     A structure in the case of using top-gate transistors is illustrated in  FIG. 20C . 
     For example, a semiconductor layer including polycrystalline silicon, a single crystal silicon film that is transferred from a single crystal silicon substrate, or the like can be used in the transistor  302   t  and the transistor  303   t  illustrated in  FIG. 20C . 
     [Structure Example 3] 
       FIGS. 21A to 21C  are cross-sectional views of a touch panel  505 B. The touch panel  505 B described in this embodiment is different from the touch panel  505 A in Structure Example 2 in that received image data is displayed on the side where the transistors are provided, that the touch sensor is provided on the substrate  701  side of the display portion, and that the FPC  509 ( 2 ) is provided on the same side as the FPC  509 ( 1 ). Different structures will be described in detail below, and the above description is referred to for the other similar structures. 
     The coloring layer  367 R is positioned in a region overlapping with the light-emitting element  350 R. The light-emitting element  350 R illustrated in  FIG. 21A  emits light to the side where the transistor  302   t  is provided. Accordingly, part of light emitted from the light-emitting element  350 R passes through the coloring layer  367 R and is emitted to the outside of the light-emitting module  380 R as indicated by an arrow in  FIG. 21A . 
     The touch panel  505 B includes the light-blocking layer  367 BM on the light extraction side. The light-blocking layer  367 BM is provided so as to surround the coloring layer (e.g., the coloring layer  367 R). 
     The touch sensor  595  is provided not on the substrate  711  side but on the substrate  701  side (see  FIG. 21A ). 
     The adhesive layer  597  bonds the substrate  590  to the substrate  701  so that the touch sensor  595  overlaps with the display portion. The adhesive layer  597  transmits light. 
     Note that a structure in the case of using bottom-gate transistors in the display portion  501  is illustrated in  FIGS. 21A and 21B . 
     For example, a semiconductor layer containing an oxide semiconductor, amorphous silicon, or the like can be used in the transistor  302   t  and the transistor  303   t  illustrated in  FIG. 21A . 
     For example, a semiconductor layer containing polycrystalline silicon can be used in the transistor  302   t  and the transistor  303   t  illustrated in  FIG. 21B . 
     A structure in the case of using top-gate transistors is illustrated in  FIG. 21C . 
     For example, a semiconductor layer containing polycrystalline silicon, a single crystal silicon film that is transferred, or the like can be used in the transistor  302   t  and the transistor  303   t  illustrated in  FIG. 21C . 
     [Structural Example of Touch Sensor] 
     A more specific structure example of the touch sensor  595  is described below with reference to drawings. 
       FIG. 22A  is a schematic top view of the touch sensor  595 . The touch sensor  595  includes a plurality of electrodes  531 , a plurality of electrodes  532 , a plurality of wirings  541 , and a plurality of wirings  542  over a substrate  590 . The substrate  590  is provided with an FPC  550  which is electrically connected to each of the plurality of wirings  541  and the plurality of wirings  542 . 
       FIG. 22B  shows an enlarged view of a region surrounded by a dashed dotted line in  FIG. 22A . The electrodes  531  are each in the form of a series of rhombic electrode patterns aligned in a lateral direction of this figure. The rhombic electrode patterns aligned in a line are electrically connected to each other. The electrodes  532  are also each in the form of a series of rhombic electrode patterns aligned in a longitudinal direction in this figure and the rhombic electrode patterns aligned in a line are electrically connected. Part of the electrode  531  and part of the electrode  532  overlap and intersect with each other. At this intersection portion, an insulator is sandwiched in order to avoid an electrical short-circuit between the electrode  531  and the electrode  532 . 
     As shown in  FIG. 22C , the electrodes  532  may form a plurality of island-shape rhombic electrodes  533  and bridge electrodes  534 . The plurality of island-shape rhombic electrodes  533  are aligned in a longitudinal direction in this figure, and two adjacent electrodes  533  are electrically connected to each other by the bridge electrode  534 . Such a structure makes it possible that the electrodes  533  and the electrodes  531  can be formed at the same time by processing the same conductive film. This can prevent variations in the thickness of these films, and can prevent the resistance value and the light transmittance of each electrode from varying from place to place. Note that although the electrodes  532  include the bridge electrodes  534  here, the electrodes  531  may have such a structure. 
     As shown in  FIG. 22D , a design in which rhombic electrode patterns of the electrodes  531  and  532  shown in  FIG. 22B  are hollowed out and only edge portions are left may be used. At that time, when the electrodes  531  and the electrodes  532  are too small in width for the users to see, the electrodes  531  and the electrodes  532  can be formed using a light-blocking material such as a metal or an alloy, as described later. In addition, either the electrodes  531  or the electrodes  532  shown in  FIG. 22D  may include the above bridge electrodes  534 . 
     One of the electrodes  531  is electrically connected to one of the wirings  541 . One of the electrodes  532  is electrically connected to one of the wirings  542 . 
     When a touch panel is formed in such a manner that the touch sensor  595  is stacked over a display surface of the display panel, a light-transmitting conductive material is preferably used for the electrodes  531  and the electrodes  532 . In the case where a light-transmitting conductive material is used for the electrodes  531  and the electrodes  532  and light from the display panel is extracted through the electrodes  531  or the electrodes  532 , it is preferable that a conductive film containing the same conductive material be arranged between the electrodes  531  and the electrodes  532  as a dummy pattern. Part of a space between the electrodes  531  and the electrodes  532  is filled with the dummy pattern, which can reduce variation in light transmittance. As a result, unevenness in luminance of light transmitted through the touch sensor  595  can be reduced. 
     As a light-transmitting conductive material, a conductive oxide such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, or zinc oxide to which gallium is added can be used. Note that a film including graphene can be used as well. The film including graphene can be formed, for example, by reducing a film containing graphene oxide. As a reducing method, a method with application of heat or the like can be employed. 
     Further, a metal film or an alloy film which is thin enough to have a light-transmitting property can be used. For example, a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or titanium, or an alloy material containing any of these metal materials can be used. Alternatively, a nitride of the metal material or the alloy material (e.g., titanium nitride), or the like may be used. Alternatively, a stacked film in which two or more of conductive films containing the above materials are stacked may be used. 
     For the electrodes  531  and the electrodes  532 , a conductive film which is processed to be too thin to see by the users may be used. Such a conductive film is processed into a lattice shape (a mesh shape), for example, which makes it possible to achieve high conductivity and high visibility of the display device. It is preferable that the conductive film have a portion in which the width is greater than or equal to 30 nm and less than or equal to 100 μm, preferably greater than or equal to 50 nm and less than or equal to 50 μm, and further preferably greater than or equal to 50 nm and less than or equal to 20 μm. In particular, the conductive film having the pattern width of 10 μm or less is extremely difficult to see by the users, which is preferable. 
     As examples, enlarged schematic views of part of the electrodes  531  or the electrodes  532  (part in a circle formed by a dashed-dotted line in  FIG. 22B ) are shown in  FIGS. 23A to 23D .  FIG. 23A  shows an example of the case in which a lattice-shape conductive film  561  is used. The lattice-shape conductive film  561  is preferably placed so as not to overlap the display element included in the display device because light from the display device is not blocked. In that case, it is preferable that the direction of the lattice be provided so as to be the same as the direction of the display element arrangement and that the pitch of the lattice be an integer multiple of the pitch of the display element arrangement. 
       FIG. 23B  shows an example of a lattice-shape conductive film  562 , which is processed so as to be provided with triangle openings. Such a structure makes it possible to further reduce the resistance compared with the structure shown in  FIG. 23A . 
     In addition, a conductive film  563 , which has an irregular pattern shape, may be used as shown in  FIG. 23C . Such a structure can prevent generation of moiré when overlapping with the display portion of the display device. Note that “moiré” refers to a fringe pattern created by diffraction or interference when external light or the like passes through or external light is reflected by narrow conductive films or the like spaced uniformly. 
     Conductive nanowires may be used for the electrodes  531  and the electrodes  532 .  FIG. 23D  shows an example of the case in which nanowires  564  are used. The nanowires  564  are dispersed at appropriate density so as to be in contact with the adjacent nanowires, which can form a two-dimensional network; therefore, a conductive film with extremely high light-transmitting property can be provided. For example, a nanowire which has a mean value of the diameters of greater than or equal to 1 nm and less than or equal to 100 nm, preferably greater than or equal to 5 nm and less than or equal to 50 nm, further preferably greater than or equal to 5 nm and less than or equal to 25 nm can be used. As the nanowire  564 , a metal nanowire such as an Ag nanowire, a Cu nanowire, and an Al nanowire, a carbon nanotube, or the like can be used. In the case of using an Ag nanowire, for example, light transmittance of 89% or more and a sheet resistance of 40 ohm/square or more and 100 ohm/square or less can be achieved. 
     Although examples in which a plurality of rhombuses are aligned in one direction are shown in  FIG. 22A  and the like as top surface shapes of the electrodes  531  and the electrodes  532 , the shapes of the electrodes  531  and the electrodes  532  are not limited thereto and can have various top surface shapes such as a belt shape (a rectangular shape), a belt shape having a curve, and a zigzag shape. In addition, although the above shows the electrodes  531  and the electrodes  532  are arranged to be perpendicular to each other, they are not necessarily arranged to be perpendicular and the angle formed by two of the electrodes may be less than 90°. 
       FIGS. 24A to 24C  illustrate examples of the case where electrodes  536  and electrodes  537 , which have a top surface shape of thin lines, are used instead of the electrodes  531  and the electrodes  532 .  FIG. 24A  shows an example in which linear electrodes  536  and  537  are arranged so as to form a lattice shape. 
       FIG. 24B  shows an example in which the electrodes  536  and the electrodes  537  have a top surface shape of a zigzag shape. As shown in  FIG. 24B , the electrodes  536  and the electrodes  537  are arranged so as not to cross the straight-line portions at the centers but so as to place the centers of the straight-line portions in different positions from each other; therefore, the length of closely facing parallel parts of the electrodes  536  and the electrodes  537  can be longer. This is preferable because the capacitance between the electrodes can be increased and the sensitivity can be increased. Alternatively, as shown in  FIG. 24C , the electrodes  536  and the electrodes  537  are arranged so as to have a design in which part of the straight-line portion of a zigzag shape is projected, which can increase the capacitance between the electrodes because the length of the parts facing each other can be longer even when the centers of the straight-line portions are placed in the same position. 
       FIGS. 25A to 25C  show enlarged views of a region surrounded by a dashed dotted line in  FIG. 24B , and  FIGS. 25D to 25F  show enlarged views of a region surrounded by a dashed dotted line in  FIG. 24C . In these drawings, the electrodes  536 , the electrodes  537 , and intersection portions  538  at which the electrodes  536  and the electrodes  537  intersect are illustrated. The straight-line portions of the electrodes  536  and the electrodes  537  shown in  FIGS. 25A and 25D  may have a serpentine shape that meanders with angled corners as shown in  FIGS. 25B and 25E  or may have a serpentine shape that continuously meanders as shown in  FIGS. 25C and 25F . 
     [Structure Example 4] 
     As illustrated in  FIG. 26 , a touch panel  500 TP includes a display portion  500  and an input portion  600  that overlap each other.  FIG. 27  is a cross-sectional view taken along the dashed-dotted line Z 1 -Z 2  in  FIG. 26 . 
     Individual components included in the touch panel  500 TP are described below. Note that these components cannot be clearly distinguished and one component also serves as another component or include part of another component in some cases. Note that the touch panel  500 TP in which the input portion  600  overlaps with the display portion  500  is also referred to as a touch panel. 
     The input portion  600  includes a plurality of sensing units  602  arranged in a matrix. The input portion  600  also includes a selection signal line GL, a control line RES, a signal line DL, and the like. 
     The selection signal line GL and the control line RES are electrically connected to the plurality of sensing units  602  that are arranged in the row direction (indicated by the arrow R in  FIG. 26 ). The signal line DL is electrically connected to the plurality of sensing units  602  that are arranged in the column direction (indicated by the arrow C in  FIG. 26 ). 
     The sensing unit  602  senses an object that is close thereto or in contact therewith and supplies a sensing signal. For example, the sensing unit  602  senses, for example, capacitance, illuminance, magnetic force, electric waves, or pressure and supplies data based on the sensed physical quantity. Specifically, a capacitor, a photoelectric conversion element, a magnetic sensing element, a piezoelectric element, a resonator, or the like can be used as the sensing element. 
     The sensing unit  602  senses, for example, a change in capacitance between the sensing unit  602  and an object close thereto or an object in contact therewith. 
     Note that when an object having a dielectric constant higher than that of the air, such as a finger, comes close to a conductive film in the air, the capacitance between the finger and the conductive film changes. The sensing unit  602  can sense the capacitance change and supply sensing data. 
     For example, distribution of charge occurs between the conductive film and the capacitor owing to the change in the electrostatic capacitance, so that the voltage across the capacitor is changed. This voltage change can be used as the sensing signal. 
     The sensing unit  602  is provided with a sensor circuit. The sensor circuit is electrically connected to the selection signal line GL, the control line RES, the signal line DL, or the like. 
     The sensor circuit includes a transistor, a sensor element, and/or the like. For example, a conductive film and a capacitor electrically connected to the conductive film can be used for the sensor circuit. A capacitor and a transistor electrically connected to the capacitor can also be used for the sensor circuit. 
     For example, a capacitor  650  including an insulating layer  653 , and a first electrode  651  and a second electrode  652  between which the insulating layer  653  is provided can be used for the sensor circuit (see  FIG. 27 ). Specifically, the voltage between the electrodes of the capacitor  650  changes when an object approaches the conductive film which is electrically connected to one electrode of the capacitor  650 . 
     The sensing unit  602  includes a switch that can be turned on or off in accordance with a control signal. For example, a transistor M 12  can be used as the switch. 
     A transistor which amplifies a sensing signal can be used in the sensing unit  602 . 
     Transistors manufactured through the same process can be used as the transistor that amplifies a sensing signal and the switch. This allows the input portion  600  to be provided through a simplified process. 
     The sensing unit  602  includes a plurality of window portions  667  arranged in a matrix. The window portions  667  transmit visible light. A light-blocking layer BM may be provided between the window portions  667 . 
     A coloring layer is provided in a position overlapping with the window portion  667  in the touch panel  500 TP. The coloring layer transmits light of a predetermined color. Note that the coloring layer can be referred to as a color filter. For example, a coloring layer  367 B transmitting blue light, a coloring layer  367 G transmitting green light, and a coloring layer  367 R transmitting red light can be used. Alternatively, a coloring layer transmitting yellow light or white light may be used. 
     The display portion  500  includes the plurality of pixels  302  arranged in a matrix. The pixel  302  is positioned so as to overlap with the window portions  667  of the input portion  600 . The pixels  302  may be arranged at higher resolution than the sensing units  602 . Each pixel has the same structure as Structure Example 1; thus, description is omitted. 
     The touch panel  500 TP includes the input portion  600  that includes the plurality of sensing units  602  arranged in a matrix and the window portions  667  transmitting visible light, the display portion  500  that includes the plurality of pixels  302  overlapping with the window portions  667 , and the coloring layers between the window portions  667  and the pixels  302 . Each of the sensing units includes a switch that can reduce interference in another sensing unit. 
     Thus, sensing data obtained by each sensor unit can be supplied together with the positional information of the sensor unit. In addition, sensing data can be supplied in relation to the positional data of the pixel for displaying an image. In addition, the sensor unit which does not supply the sensing data is not electrically connected to a signal line, whereby interference with the sensor unit which supplies a sensing signal can be reduced. Consequently, the novel touch panel  500 TP that is highly convenient or highly reliable can be provided. 
     For example, the input portion  600  of the touch panel  500 TP can sense sensing data and supply the sensing data together with the positional data. Specifically, a user of the touch panel  500 TP can make a variety of gestures (e.g., tap, drag, swipe, and pinch-in operation) using, as a pointer, his/her finger or the like on the input portion  600 . 
     The input portion  600  can sense a finger or the like that comes close to or is in contact with the input portion  600  and supply sensing data including a sensed position, path, or the like. 
     An arithmetic unit determines whether or not supplied data satisfies a predetermined condition on the basis of a program or the like and executes an instruction associated with a predetermined gesture. 
     Thus, a user of the input portion  600  can make the predetermined gesture with his/her finger or the like and make the arithmetic unit execute an instruction associated with the predetermined gesture. 
     For example, first, the input portion  600  of the touch panel  500 TP selects one sensing unit X from the plurality of sensing units that can supply sensing data to one signal line. Then, electrical continuity between the signal line and the sensing units other than the sensing unit X is not established. This can reduce interference of the other sensing units in the sensing unit X. 
     Specifically, interference of sensing elements of the other sensing units in a sensing element of the sensing unit X can be reduced. 
     For example, in the case where a capacitor and a conductive film to which one electrode of the capacitor is electrically connected are used for the sensing element, interference of the potentials of the conductive films of the other sensing units in the potential of the conductive film of the sensing unit X can be reduced. 
     Thus, the touch panel  500 TP can drive the sensing unit and supply sensing data independently of its size. The touch panel  500 TP can have a variety of sizes, for example, ranging from a size for a hand-held device to a size for an electronic blackboard. 
     The touch panel  500 TP can be folded and unfolded. Even in the case where interference of the other sensing units in the sensing unit X is different between the folded state and the unfolded state, the sensing unit can be driven and sensing data can be supplied without dependence on the state of the touch panel  500 TP. 
     The display portion  500  of the touch panel  500 TP can be supplied with display data. For example, an arithmetic unit can supply the display data. 
     In addition to the above structure, the touch panel  500 TP can have the following structure. 
     The touch panel  500 TP may include a driver circuit  603   g  or a driver circuit  603   d . In addition, the touch panel  500 TP may be electrically connected to an FPC1. 
     The driver circuit  603   g  can supply selection signals at predetermined timings, for example. Specifically, the driver circuit  603   g  supplies selection signals to the selection signal lines GL row by row in a predetermined order. Any of a variety of circuits can be used as the driver circuit  603   g . For example, a shift register, a flip flop circuit, a combination circuit, or the like can be used. 
     The driver circuit  603   d  supplies sensing data on the basis of a sensing signal supplied from the sensing unit. Any of a variety of circuits can be used as the driver circuit  603   d . For example, a circuit that can form a source follower circuit or a current mirror circuit by being electrically connected to the sensing circuit in the sensing unit can be used as the driver circuit  603   d . In addition, an analog-to-digital converter circuit that converts a sensing signal into a digital signal may be provided in the driver circuit  603   d.    
     The FPC1 supplies a timing signal, a power supply potential, or the like and is supplied with a sensing signal. 
     The touch panel  500 TP may include a driver circuit  503   g , a driver circuit  503   s , a wiring  311 , and a terminal  319 . In addition, the touch panel  500 TP may be electrically connected to an FPC2. 
     In addition, a protective layer  670  that prevents damage and protects the touch panel  500 TP may be provided. For example, a ceramic coat layer or a hard coat layer can be used as the protective layer  670 . Specifically, a layer containing aluminum oxide or a UV curable resin can be used. 
     In the case of a transflective liquid crystal display or a reflective liquid crystal display, some of or all of pixel electrodes function as reflective electrodes. For example, some or all of pixel electrodes are formed to contain aluminum, silver, or the like. 
     Furthermore, a memory circuit such as an SRAM can be provided under the reflective electrodes, leading to lower power consumption. A structure suitable for employed display elements can be selected from among a variety of structures of pixel circuits. 
     The touch panel described in this embodiment can be used instead of the display panel  100  included in the display device  10  in Embodiment 1. In this case, a touch panel with a structure in which a plurality of FPCs connected to the touch panel are extracted from the same side, such as the touch panel  390  and the touch panel  505 B, can be preferably used. Note that in the case where a touch panel is used instead of the display panel  100 , the display device  10  can be referred to as an input/output device. 
     The adhesive layer  107  that bonds the plurality of touch panels to the substrate  106  is preferably provided so that the top surfaces of the touch sensors  595  (or the input portions  600 ) of these touch panels are level with each other and the top surfaces are parallel to the substrate  106 . The distances between the surface of the input/output device (i.e., the surface of the substrate  106 ) and the touch sensors  595  (or the input portions  600 ) of the touch panels are made the same, whereby location dependence (also called in-plane variation) of detection sensitivity can be reduced. 
     This embodiment can be combined with any other embodiment as appropriate. 
     EXAMPLE 
     In this example, an example in which a display device of one embodiment of the present invention was manufactured is described. 
     The display device  20  includes four display panels  80  arranged in a matrix of two rows and two columns (two display panels in the horizontal direction and two display panels in the longitudinal direction). Table 1 shows the specifications of the display panel  80  in this example.  FIG. 28A  is a photograph of the display panel  80  displaying an image. 
     
       
         
           
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Specifications 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 Panel Size 
                 13.5 inches 
               
               
                 Driving Method 
                 Active matrix 
               
               
                 Resolution 
                 1280 (H) × 720 (V) HD 
               
               
                 Pixel Density 
                 108 ppi 
               
               
                 Aperture Ratio 
                 61.0% 
               
               
                 Coloring Method 
                 White tandem OLED, Top emission, Color filter 
               
               
                   
                 (WTC technique) 
               
               
                 Pixel Arrangement 
                 RGBY checker 
               
               
                 Source Driver 
                 COF + DeMUX 
               
               
                 Scan Driver 
                 Integrated 
               
               
                 Thickness 
                 Lower than or equal to 100 μm 
               
               
                 at transparent bezel 
               
               
                   
               
            
           
         
       
     
       FIG. 29  is a photograph of the display device  20  displaying an image. The horizontal direction in  FIG. 29  corresponds to the X-axis direction in  FIG. 1A  and  FIG. 4A , and the longitudinal direction in  FIG. 29  corresponds to the Y-axis direction in  FIG. 1A  and  FIG. 4A . The display device  20  includes four plates  90 , four stages  91 , four driver circuits  62 , four adjusting units  63 , and the frame  21 . 
       FIGS. 30A and 30B  are photographs of one of four component groups  60  in the display device  20 . In each component group  60 , the display panel  80  and the plate  90  are fixed to each other and connected to the stage  91 .  FIG. 30A  is a photograph of the component group  60  from the diagonally front side. The display portion  41  of the display panel  80  is shown in  FIG. 30A .  FIG. 30B  is a photograph of the component group  60  from the diagonally rear side. 
     As shown in  FIG. 30A , the display panel  80  includes the transparent portion  82  in a position adjacent to two sides of the display portion  41 . As shown in  FIG. 30B , the display panel  80  is fixed to the plate  90  so that transparent portion  82  and a part of the display portion  41  extend beyond two sides of the plate  90 . In the display device  20  having such a structure, display portions  41  of the four display panels  80  can be arranged seamlessly, and an image or video without unnatural seams can be displayed on a display portion  11 C used as one display area (see  FIG. 29 ). In this example, the width of the transparent portion  82  is approximately 2 mm (see  FIG. 28B ).  FIG. 28B  is an enlarged photograph of a region surrounded by a dashed line in  FIG. 28A . 
     As shown in  FIG. 30B , the alignment of the plate  90  and the stage  91  in the horizontal direction and the longitudinal direction can be performed precisely using the depression  51 , the fastening  52 , and the guide  53  of the plate  90 . In the display device  20 , the stage  91  is fixed to the frame  21  through the adjusting unit  63 . As the adjusting unit  63 , the combination of the X-axis stage, the Y-axis stage, and the goniometer stage is used as described in Embodiment 1. In the display device  20  having such a structure, the positions of the display panels  80  can be adjusted with high precision so that the display portions  41  of the four display panels  80  are seamlessly arranged to be parallel and that the positional shift of display on the display portions  41  of the adjacent display panels  80  does not occur.  FIG. 31A  is an enlarged photograph of a region in the vicinity of the joint portion of the display portions in the display device  20  displaying an image. In  FIG. 31A , the joint portion of the display portions  41  is included in a region surrounded by a dashed line. It is shown from  FIG. 31A  that the display portions  41  of the four display panels  80  in the display device  20  are arranged so that the positional shift of display does not occur along the joint portion. 
     Note that the first surface of the plate  90  may be provided with a fixing instrument. In the case where the display panel  80  includes a chip on film (COF), the COF can be fixed to the first surface of the plate  90  using the fixing instrument.  FIG. 34  is a photograph of the plate  90  in which the fixing instrument  54  is provided in the vicinity of the convexly curved surface of the first surface and the display panel  80  fixed to the plate  90 . The fixing instrument  54  includes a member  54   a  and a member  54   b . A material of the member  54   a  is not particularly limited. The member  54   b  is preferably formed of an insulator. The member  54   a  is formed of a material similar to that of the plate  90 . The member  54   b  is formed of plastic. By fixing the COF of the display device  20  to the member  54   b  with a screw or the like, the display panel  80  can be prevented from being broken when the plate  90  to which the display panel  80  is fixed is carried. 
     The driver circuits  62  can correct variation in display performance of the display panels  80  because of having a function of adjusting color tone, luminance, or the like of display of the display panels  80 . Thus, the display portion  11 C of the display device  20  can perform display with high display quality in which variation in color tone, luminance, or the like is suppressed. 
       FIG. 31B  is a photograph of the display device  20  from the diagonally front side with respect to the display portion  11 C. As shown in  FIG. 31B , the first portion  44  of the display panel  80  is bent to the rear surface side of the display surface of the display panel  80  along the convexly curved surface of the plate  50 . Thus, the driver circuit  62  provided on the rear surface side of the display panel  80  can be easily connected to the external electrode  46 . In addition, the external electrode  46  or the like does not hinder overlapping of the display panels  80 , so that the display surface of the display portion  11 C can be made almost flat with few steps. Note that in  FIG. 31B , the lower (rear) display panel is denoted by  80   a , whereas the upper (front) display panel is denoted by  80   b.    
     In the display device  20 , the display portion  11 C has a size of 27 inches diagonal (the size of the display portion  41  of one display panel  80  is 13.5 inches diagonal), 2560×1440 effective pixels, the pixel size of 234 μm×234 μm, a resolution of 108 ppi, and an aperture ratio of 61.0%. A built-in scan driver and an external source driver attached by chip on film (COF) were used. 
       FIG. 32  is a photograph of the display device  10  displaying an image. The display device  10  includes display panels  80  of this example arranged in a matrix of six rows and six columns (six display panels in each of the horizontal direction and the longitudinal direction).  FIG. 33A  is a photograph of the rear side of the display surface of the display device  10 .  FIG. 33B  is an enlarged photograph of a portion surrounded by a dotted line in  FIG. 33A .  FIG. 33B  is a photograph showing a state in which the cables  64  connected to the driver circuits  62  in  FIG. 33A  are removed. 
     The display device  10  includes  36  plates  90 ,  36  stages  91 ,  36  driver circuits  62 ,  36  adjusting units  63 , and the frame  21 . The display device  10  also includes four video signal dividers  22  and two video output units  23  (not shown). In this example, an uncompressed disk recorder is used as the video output unit  23 . Note that in the display device  10 , a display portion  11 D has a size of 81 inches diagonal and the number of effective pixels is 7680×4320 (8K). 
     In this example, as the light-emitting element included in the display portion  41 , a tandem (stack) organic EL element emitting white light was used. The light-emitting element has a top emission structure. Light from the light-emitting element is extracted outside through a color filter. 
     As the transistor, a transistor including a c-axis aligned crystalline oxide semiconductor (CAAC-OS) was used. Unlike amorphous semiconductor, the CAAC-OS has few defect states, so that the reliability of the transistor can be improved. In addition, because laser crystallization is not needed for formation of a CAAC-OS, a uniform film can be formed even over a large-sized glass substrate or the like. Moreover, since the CAAC-OS does not have a grain boundary, stress that is caused by bending a flexible display panel does not easily make a crack in a CAAC-OS film. 
     A CAAC-OS is an oxide semiconductor having c-axis alignment in a direction substantially perpendicular to the film surface. It has been found that oxide semiconductors have a variety of crystal structures other than a single-crystal structure. An example of such structures is a nano-crystal (nc) structure, which is an aggregate of nanoscale microcrystals. The crystallinity of a CAAC-OS structure is lower than that of a single-crystal structure and higher than that of an nc structure. 
     In this example, a channel-etched transistor including an In—Ga—Zn-based oxide was used. The transistor was fabricated over a glass substrate at a process temperature lower than 500° C. 
     As shown in  FIG. 29  and  FIG. 32 , in one embodiment of the present invention, a large-sized display device in which a joint portion of display portions is hardly recognized by a user was able to be obtained. 
     At least part of this example can be implemented in combination with any of the embodiments described in this specification as appropriate. 
     REFERENCE NUMERALS 
     
         
           10 : display device,  11 A: display portion,  11 B: display portion,  11 C: display portion,  11 D: display portion,  20 : display device,  20 A: display device,  20 B: display device,  21 : frame,  21 A: frame,  21 B: frame,  22 : video signal divider,  23 : video output unit,  30 : display panel,  30   a : display panel,  30   b : display panel,  31 : pixel,  31   a : pixel,  31   b : pixel,  32 : transparent portion,  32   b : transparent portion,  33   c : operating circuit,  33   d : operating circuit,  34   c : wiring,  34   d : wiring,  35 : wiring,  36 : substrate,  37 : substrate,  38 : adhesive layer,  40 : display panel,  40   a : display panel,  40   b : display panel,  41 : display portion,  41   a : display portion,  41   b : display portion,  42 : transparent portion,  42   b : transparent portion,  43 : operating circuit portion,  43   a : operating circuit portion,  44 : first portion,  44   a : first portion,  44   b : first portion,  45 : terminal,  45   b : terminal,  46 : external electrode,  46   a : external electrode,  46   b : external electrode,  50 : plate,  50   a : plate,  50   b : plate,  52 : fastening,  52   a : fastening,  53 : guide,  53   a : guide,  54 : fixing instrument,  54   a : member,  54   b : member,  60 : component group,  61 : stage,  61   a : stage,  61   b : stage,  62 : driver circuit,  62   a : driver circuit,  62   b : driver circuit,  63 : adjusting unit,  63   a : adjusting unit,  63   b : adjusting unit,  64 : cable,  64   a : cable,  64   b : cable,  65 : cable,  80 : display panel,  80   a : display panel,  80   b : display panel,  82 : transparent portion,  82   b : transparent portion,  90 : plate,  90   a : plate,  90   b : plate,  91 : stage,  91   a : stage,  91   b : stage,  100 : display panel,  106 : substrate,  107 : adhesive layer,  301 : display portion,  302 : pixel,  302 B: sub-pixel,  302 G: sub-pixel,  302 R: sub-pixel,  302   t : transistor,  303   c : capacitor,  303   g ( 1 ): scan line driver circuit,  303   g ( 2 ): imaging pixel driver circuit,  303   s ( 1 ): image signal line driver circuit,  303   s ( 2 ): imaging signal line driver circuit,  303   t : transistor,  304 : gate,  308 : imaging pixel,  308   p : photoelectric conversion element,  308   t : transistor,  309 : FPC,  311 : wiring,  319 : terminal,  321 : insulating layer,  328 : partition,  329 : spacer,  350 R: light-emitting element,  351 R: lower electrode,  352 : upper electrode,  353 : EL layer,  353   a : EL layer,  353   b : EL layer,  354 : intermediate layer,  360 : adhesive layer,  367 B: coloring layer,  367 BM: light-blocking layer,  367 G: coloring layer,  367   p : anti-reflective layer,  367 R: coloring layer,  380 B: light-emitting module,  380 G: light-emitting module,  380 R: light-emitting module,  390 : touch panel,  500 : display portion,  500 TP: touch panel,  501 : display portion,  503   g : driver circuit,  503   s : driver circuit,  505 A: touch panel,  505 B: touch panel,  509 ( 1 ): FPC,  509 ( 2 ): FPC,  531 : electrode,  532 : electrode,  533 : electrode,  534 : bridge electrode,  536 : electrode,  537 : electrode,  538 : intersection portion,  541 : wiring,  542 : wiring,  550 : FPC,  561 : conductive film,  562 : conductive film,  563 : conductive film,  564 : nanowire,  590 : substrate,  591 : electrode,  592 : electrode,  593 : insulating layer,  594 : wiring,  595 : touch sensor,  597 : adhesive layer,  598 : wiring,  599 : connection layer,  600 : input portion,  602 : sensing unit,  603   d : driver circuit,  603   g  : driver circuit,  650 : capacitor,  651 : electrode,  652 : electrode,  653 : insulating layer,  667 : window portion,  670 : protective layer,  701 : substrate,  703 : adhesive layer,  705 : insulating layer,  711 : substrate,  713 : adhesive layer,  715 : insulating layer,  723 : adhesive layer,  804 : display portion,  806 : operating circuit portion,  808 : FPC,  810 : transparent portion,  815 : insulating layer,  816 : insulating layer,  817 : insulating layer,  817   a : insulating layer,  817   b : insulating layer,  820 : transistor,  821 : insulating layer,  822 : adhesive layer,  823 : spacer,  824 : transistor,  825 : connector,  830 : light-emitting element,  831 : lower electrode,  832 : optical adjusting layer,  832 B: optical adjusting layer,  832 R: optical adjusting layer,  833 : EL layer,  835 : upper electrode,  845 : coloring layer,  847 : light-blocking layer,  849 : overcoat,  856 : conductive layer,  857 : conductive layer,  860 : auxiliary electrode,  860   a : conductive layer,  860   b : conductive layer,  870 : transistor,  871 : capacitor. 
       
    
     This application is based on Japanese Patent Application serial no. 2014-206873 filed with Japan Patent Office on Oct. 8, 2014, Japanese Patent Application serial no. 2014-219086 filed with Japan Patent Office on Oct. 28, 2014, Japanese Patent Application serial no. 2014-240213 filed with Japan Patent Office on Nov. 27, 2014, and Japanese Patent Application serial no. 2015-043931 filed with Japan Patent Office on Mar. 5, 2015, the entire contents of which are hereby incorporated by reference.