Patent Publication Number: US-11659636-B2

Title: Display device and electronic device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 16/121,702, filed Sep. 5, 2018, now allowed, which is a continuation of U.S. application Ser. No. 14/806,950, filed Jul. 23, 2015, now U.S. Pat. No. 10,159,135, which claims the benefit of foreign priority applications filed in Japan as Serial No. 2014-156168 on Jul. 31, 2014, Serial No. 2014-219131 on Oct. 28, 2014, Serial No. 2014-243195 on Dec. 1, 2014, and Serial No. 2015-109642 on May 29, 2015, all of which are incorporated by reference. 
    
    
     TECHNICAL FIELD 
     One embodiment of the present invention relates to a display device, an electronic device, or a manufacturing method thereof. The present invention particularly relates to a display device or an electronic device utilizing electroluminescence (hereinafter also referred to as EL) or a manufacturing method thereof. 
     Note that one embodiment of the present invention is not limited to the above technical field. 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 power storage device, a storage device, an electronic device, a lighting device, an input device (e.g., a touch sensor), an input-output device (e.g., a touch panel), a driving method thereof, and a manufacturing method thereof. 
     BACKGROUND ART 
     In recent years, larger display devices have been required. Examples of uses for a large display device include a television device for home use (also referred to as a TV or a television receiver), digital signage, and a public information display (PID). A larger display region of a display device can provide the increased amount of information at a time. In addition, a larger display region attracts more attention, so that the effectiveness of the advertisement is expected to be increased, for example. 
     In addition, for application to mobile devices, larger display devices have been required. In recent years, browsability has been considered to be improved by increasing the amount of information to be displayed at one time with an increase of a display region of the display device. 
     Light-emitting elements utilizing EL (also referred to as EL elements) have features such as ease of thinning and lightening, high-speed response to input signal, and driving with a direct-current low voltage source; therefore, application of the light-emitting elements to display devices has been proposed. 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. 
     PATENT DOCUMENT 
     [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 increase the size of a display device. Another object of one embodiment of the present invention is to suppress display unevenness or luminance unevenness of a display device. Another object of one embodiment of the present invention is to reduce the thickness or weight of a display device. Another object of one embodiment of the present invention is to provide a display device that can display an image along a curved surface. Another object of one embodiment of the present invention is to provide a highly browsable display device. 
     Another object of one embodiment of the present invention is to provide a novel display device, a novel electronic device, or the like. 
     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. Other objects can be derived from the description of the specification, the drawings, and the claims. 
     One embodiment of the present invention is a display device at least part of which is flexible. The display device includes a first display panel, a second display panel, and a light-transmitting layer. The first display panel includes a first region. The first region has a function of performing display. The second display panel includes a second region and a third region. The second region has a function of performing display. The third region is adjacent to the second region and has a function of transmitting visible light. In the light-transmitting layer, a transmittance with respect to light in a wavelength range of 450 nm to 700 nm is 80% or more on the average. A refractive index of the light-transmitting layer is higher than that of air. The light-transmitting layer is between the first display panel and the second display panel. The light-transmitting layer is positioned on both a display surface side of the first display panel and a side opposite to a display surface side of the second display panel. The third region includes a region that overlaps the first region with the light-transmitting layer provided therebetween. 
     Note that in one embodiment of the present invention, in at least part of the light-transmitting layer, a transmittance with respect to light in a wavelength range of 450 nm to 700 nm may be 80% or more, preferably 90% or more. Similarly, a refractive index of at least part of the light-transmitting layer may be higher than that of air and preferably higher than or equal to 1.3 and lower than or equal to 1.8. 
     In each of the above structures, the first region and the second region may each include a light-emitting element. 
     In each of the above structures, the third region may include a bonding layer. Here, the bonding layer may be positioned along part of an outer edge of the second region. 
     In each of the above structures, the second display panel may include a fourth region. The fourth region is adjacent to the second region and has a function of blocking visible light. It is preferred that the fourth region do not include a region overlapping with the first region. The fourth region may include a wiring. Here, the wiring may be electrically connected to a light-emitting element included in the second region. The wiring may be positioned along another part of the outer edge of the second region. 
     In each of the above structures, it is preferred that the light-transmitting layer be detachably in contact with at least one of the first display panel and the second display panel. 
     In each of the above structures, the light-transmitting layer preferably includes an inert material. 
     In each of the above structures, the light-transmitting layer preferably includes a non-volatile material. 
     In each of the above structures, the light-transmitting layer may include a material with a viscosity of greater than or equal to 1 mPa·s and less than or equal to 1000 Pa·s. The viscosity of the material is preferably 1 Pa·s or more, more preferably 10 Pa·s or more, still more preferably 100 Pa·s or more. 
     In each of the above structures, a flexible printed circuit (FPC) may be included. Here, the FPC may be electrically connected with the first display panel. The FPC preferably includes a region overlapping with the second region. 
     One embodiment of the present invention also includes an electronic device or a lighting device including a display device with any of the above structures. For example, one embodiment of the present invention is an electronic device including the display device with any of the above structures, and an antenna, a battery, a housing, a speaker, a microphone, an operation switch, or an operation button. 
     According to one embodiment of the present invention, the display device can be increased in size. According to one embodiment of the present invention, display unevenness or luminance unevenness of the display device can be suppressed. According to one embodiment of the present invention, the display device can be thin or lightweight. According to one embodiment of the present invention, a display device that can display an image along a curved surface can be provided. According to one embodiment of the present invention, a highly browsable display device can be provided. 
     According to one embodiment of the present invention, a novel display device, a novel electronic device, or the like can be provided. 
     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 can be derived from the description of the specification, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIGS.  1 A to  1 C  illustrate examples of a display device. 
         FIGS.  2 A to  2 D  illustrate examples of a display panel. 
         FIGS.  3 A to  3 C  illustrate examples of a display device. 
         FIGS.  4 A to  4 F  illustrate examples of a display device. 
         FIGS.  5 A to  5 F  illustrate examples of a display device. 
         FIGS.  6 A to  6 C  illustrate an example of a display panel. 
         FIGS.  7 A to  7 C  illustrate an example of a display panel. 
         FIGS.  8 A to  8 C  illustrate examples of a display device. 
         FIGS.  9 A to  9 C  illustrate examples of a light-emitting panel. 
         FIGS.  10 A to  10 C  illustrate examples of a light-emitting panel. 
         FIGS.  11 A and  11 B  illustrate examples of a light-emitting panel. 
         FIGS.  12 A to  12 C  illustrate an example of a touch panel. 
         FIGS.  13 A and  13 B  illustrate an example of a touch panel. 
         FIGS.  14 A to  14 C  illustrate examples of a touch panel. 
         FIGS.  15 A to  15 C  illustrate examples of a touch panel. 
         FIG.  16    illustrates an example of a touch panel. 
         FIG.  17    illustrates an example of a touch panel. 
         FIGS.  18 A to  18 F  illustrate examples of an electronic device and a lighting device. 
       FIGS.  19 A 1 ,  19 A 2 ,  19 B,  19 C,  19 D,  19 E,  19 F,  19 G,  19 H, and  19 I illustrate examples of an electronic device. 
         FIG.  20    illustrates an example of a display device. 
         FIGS.  21 A and  21 B  are photographs of a display device in Example 1, and  FIG.  21 C  illustrates a display device in Example 1. 
         FIG.  22 A  illustrates a display panel in Example 1, and  FIG.  22 B  illustrates a stacked layer structure of a region transmitting visible light in Example 1. 
         FIG.  23    shows a measurement result of a transmittance with respect to light of a region transmitting visible light. 
         FIG.  24 A  is a photograph of a display device, and  FIG.  24 B  is a photograph of a display panel in Example 2. 
         FIG.  25    shows a light-emitting element in Example 2. 
         FIG.  26    shows a measurement result of luminance of a display panel in Example 2. 
         FIG.  27    shows a photograph displayed by a display device in Example 2. 
         FIG.  28 A  illustrates a display panel in Example 3, and  FIGS.  28 B and  28 C  illustrate the way to overlap the display panels. 
         FIGS.  29 A to  29 C  are photographs illustrating a bending test in Example 3, and  FIGS.  29 D and  29 E  show photographs of images displayed on display panels in Example 3. 
         FIG.  30 A  illustrates a photograph displayed by a display panel in Example 3, and  FIG.  30 B  illustrates a method for driving a display device in Example 3. 
         FIG.  31    illustrates a photograph displayed by a display device in Example 3. 
         FIG.  32    illustrates a photograph displayed by a display device in Example 3. 
     
    
    
     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. 
     In addition, the position, size, range, or the like of each structure illustrated in drawings is not accurately represented in some cases for easy understanding. Therefore, the disclosed invention is not necessarily limited to the position, the size, the range, or the like disclosed in the drawings. 
     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”. Also, the term “insulating film” can be changed into the term “insulating layer”. 
     Note that in this specification, examples of the case where X and Y are electrically connected include the case where A and B are directly connected without another element interposed therebetween and the case where one or more elements that enable electrical connection between X and Y (e.g., a switch, a transistor, a capacitor, an inductor, a resistor, a diode, a display element, a light-emitting element, or a load) are connected between X and Y. A switch is controlled to be on or off That is, a switch is conducting or not conducting (is turned on or off) to determine whether current flows therethrough or not. Alternatively, the switch has a function of selecting and changing a current path. 
     Embodiment 1 
     In this embodiment, a display device of one embodiment of the present invention will be described with reference to  FIGS.  1 A to  1 C ,  FIGS.  2 A to  2 D ,  FIGS.  3 A to  3 C ,  FIGS.  4 A to  4 F ,  FIGS.  5 A to  5 F ,  FIGS.  6 A to  6 C ,  FIGS.  7 A to  7 C , and  FIGS.  8 A to  8 C . 
     A plurality of display panels are arranged in one or more directions (e.g., in one column or in matrix), whereby a display device with a large display region can be manufactured. 
     In the case where a large display device is manufactured using a plurality of display panels, each of the display panels is not required to be large. Therefore, an apparatus for manufacturing the display panel does not need to be increased in size, so that space-saving can be achieved. In addition, since an apparatus for manufacturing small and middle-size display panel can be used, a novel manufacturing apparatus does not need to be used for increasing the size of a display device, so that manufacturing cost can be reduced. Furthermore, a decrease in yield caused by increasing the size of a display panel can be suppressed. 
     A display device having a plurality of display panels have a larger display region than a display device having one display panel when the display panels have the same size, so that the display device having the plurality of display panels have an effect of displaying more information on one screen, or the like. 
     However, each of the display panels has a non-display region that surrounds a display region. Thus, for example, in the case where output images of a plurality of display panels are used to display one image, the image appears divided to a user of the display device. 
     Although narrowing the non-display regions of display panels (using display panels with narrower frames) can prevent the images of the display panels from appearing divided, it is difficult to totally remove the non-display region. 
     In addition, a smaller non-display region leads to a decrease in the distance between the edge of the display panel and an element in the display panel, so that the element easily deteriorates by impurities entering from the outside of the display panel in some cases. 
     Thus, in the display device of one embodiment of the present invention, a plurality of display panels are arranged to partly overlap one another. In two display panels overlapping with each other, at least a display panel positioned on the display surface side (upper side) includes a region transmitting visible light that is adjacent to a display region. In the display device of one embodiment of the present invention, the display region of the display panel positioned on a lower side and the region transmitting visible light of the display panel positioned on the upper side overlap with each other. Therefore, a non-display region between the display regions of the two display panels overlapping with each other can be reduced or even removed. Accordingly, a large display device in which a seam between display panels is hardly recognized by a user can be obtained. 
     In one embodiment of the present invention, at least part of the non-display region of the display panel positioned on the upper side is a region transmitting visible light, and can overlap the display region of the display panel positioned on the lower side. In one embodiment of the present invention, at least part of the non-display region of the display panel positioned on the lower side can overlap with a display region of the display panel positioned on the upper side or a region blocking visible light thereof. It is not necessary to reduce the areas of these regions because a reduction in the area of the frame of the display device (a reduction in area except a display region) is not affected by these regions. 
     In addition, a larger non-display region leads to an increase in the distance between the edge of the display panel and an element in the display panel, so that the deterioration of the element due to impurities entering from the outside of the display panel can be suppressed. For example, in the case where an organic EL element is used as a display element, as the distance between the edge of the display panel and the organic EL element in the display panel increases, impurities such as moisture or oxygen are less likely to enter (or less likely to reach) the organic EL element from the outside of the display panel. Since a sufficient area of the non-display region can be secured in the display device of one embodiment of the present invention, a highly reliable large display device can be realized even when a display panel including an organic EL element or the like is used. 
     When air exists between the region transmitting visible light of the display panel positioned on the upper side and the display region of the display panel positioned on the lower side, part of light extracted from the display region is reflected at the interface between the display region and air and the interface between air and the region transmitting visible light, which may result in a decrease in luminance of the display. Therefore, the light extraction efficiency of the region in which a plurality of display panels overlap with each other is decreased. In addition, luminance difference occurs between part of the display region of the display panel positioned on the lower side that overlaps with the region transmitting visible light of the display panel positioned on the upper side and part thereof that does not overlap with the region transmitting visible light of the display panel positioned on the upper side, so that a seam between the display panels is easily recognized by a user in some cases. 
     In the display device of one embodiment of the present invention, a light-transmitting layer having a refractive index higher than that of air and transmitting visible light is provided between the display region and the region transmitting visible light. Thus, air can be prevented from entering between the display region and the region transmitting visible light, so that the reflection at the interface due to a difference in refractive index can be suppressed. In addition, display unevenness or luminance unevenness of the display device can be suppressed. 
     Specifically, one embodiment of the present invention is a display device including a first display panel, a second display panel, and a light-transmitting layer. The first display panel includes a first region. The first region has a function of displaying an image. The second display panel has a second region and a third region. The second region has a function of displaying an image. The third region is adjacent to the second region and has a function of transmitting visible light. In the light-transmitting layer, the transmittance of light in a wavelength range of 450 nm to 700 nm is 80% or more on the average. The light-transmitting layer has a refractive index higher than that of air. The light-transmitting layer is provided between the first display panel and the second display panel. The light-transmitting layer is positioned on both a display surface side of the first display panel and a side opposite to the display surface side of the second display panel. The third region includes a region that overlaps the first region with the light-transmitting layer provided therebetween. 
     At least part of the display device may have flexibility. At least part of the display panel may have flexibility. The display device of one embodiment of the present invention preferably includes a flexible display panel. In that case, a large curved display device or a flexible display device can be provided, and the application is expanded. Here, an organic EL element is suitably used as a display element. 
     Note that the transmittance with respect to visible light in the light-transmitting layer is preferably higher because the light extraction efficiency of the display device can be increased. For example, a transmittance with respect to light in the wavelength range of 450 nm to 700 nm of the light-transmitting layer may be 80% or more, and preferably 90% or more. 
     The difference in refractive index between the light-transmitting layer and a layer in contact with the light-transmitting layer is preferably smaller because the reflection of light can be suppressed. For example, the refractive index of the light-transmitting layer is higher than that of air, preferably higher than or equal to 1.3 and lower than or equal to 1.8. The difference in the refractive index between the light-transmitting layer and the layer in contact with the light-transmitting layer (e.g., a substrate included in the display panel) is preferably lower than or equal to 0.30, more preferably lower than or equal to 0.20, still more preferably lower than or equal to 0.15. 
     It is preferred that the light-transmitting layer be detachably in contact with at least one of the first display panel and the second display panel. In the case where each of the display panels included in the display device is detachable, when malfunction is occurred in one of display panels, for example, only the defective display panel can be easily replaced with a new display panel. By using the other display panels continuously, the display device can be used longer and at lower cost. 
     When there is no need to attach and detach the display panels, the display panels are fixed to each other with the light-transmitting layer including a material having an adhesive property (adhesive or the like). 
     Any of an inorganic material and an organic material can be used for the light-transmitting layer. A liquid substance, a gelatinous substance, or a solid substance can be used for the light-transmitting layer. 
     For the light-transmitting layer, a liquid substance such as water, a solution, a fluorine-based inactive liquid, a refractive liquid, silicone oil, or the like can be used, for example. 
     In the case where the display device is inclined to the horizontal plane (a plane perpendicular to a direction in which gravity acts) or in the case where the display device is placed so as to be perpendicular to the horizontal plane, the viscosity of a liquid substance is preferably 1 mPa·s or more, more preferably 1 Pa·s or more, still more preferably 10 Pa·s or more, and yet still preferably 100 Pa·s or more. In the case where the display device is placed so as to be parallel to the horizontal plane or the like, the viscosity of the liquid substance is not limited thereto. 
     The light-transmitting layer is preferably inactive because another layer included in the display device can be prevented from being damaged, or the like. 
     A material included in the light-transmitting layer is preferably nonvolatile. Accordingly, entry of air to the interface due to vitalization of a material used for the light-transmitting layer can be prevented. 
     For the light-transmitting layer, a high molecular material can be used. Examples of such a high molecular material include a resin such as 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, and an ethylene vinyl acetate (EVA) resin. Alternatively, a two-component-mixture-type resin may be used. A variety of curable adhesives such as a reactive curable adhesive, a thermosetting adhesive, an anaerobic adhesive, and a photo curable adhesive such as an ultraviolet curable adhesive containing at least one of these resins may be used. The adhesives are not necessarily cured in the case where the display panels are not fixed to each other, or the like. 
     The light-transmitting layer preferably has high self-attachability to an object. In addition, the light-transmitting layer preferably has high separability against an object. After the light-transmitting layer attached to the display panel is separated from the display panel, it is preferred that the light-transmitting layer be able to be attached to the display panel again. 
     In addition, it is preferred that the light-transmitting layer have no adhesiveness or low adhesiveness. Thus, attachment of the light-transmitting layer to an object and separation of the light-transmitting layer from the object can be repeated without damaging or contaminating the surface of the object. 
     As the light-transmitting layer, a film having attachability or a film having adhesiveness can be used, for example. In the case where an attachment film having a stacked-layer structure of an attachment layer or an adhesive layer and a base material is used, the attachment layer or the adhesive layer may function as the light-transmitting layer of the display device of one embodiment of the present invention, and the base material may function as a substrate included in the display panel. The attachment film may include an anchor layer between the attachment layer or the adhesive layer and the base material. The anchor layer has a function of enhancing the adhesiveness between the attachment layer or the adhesive layer and the base material. In addition, the anchor layer has a function of smoothing the coated surface of the attachment layer or that of the adhesive layer of the base material. In this manner, bubbles can be made hardly generated between the object and the light-transmitting layer. 
     For example, a film in which a silicone resin layer and a polyester film are stacked can be preferably used in the display device of one embodiment of the present invention. Here, the silicone resin layer has attachability and functions as the light-transmitting layer. The polyester film serves as a substrate included in the display panel. Note that a substrate included in the display panel may be further provided in addition to the polyester film. 
     In the case where a film in which an attachment layer, a base material, and an adhesive layer or a bonding layer are stacked is used, the attachment layer serves as the light-transmitting layer of the display device of one embodiment of the present invention; the base material functions as a substrate included in the display panel; and the adhesive layer or the bonding layer serves as a layer for attaching an element layer and the substrate of the display panel. 
     The thickness of the light-transmitting layer is not particularly limited. For example, the thickness may be greater than or equal to 1 μm and less than or equal to 50 μm. The thickness of the light-transmitting layer may be larger than 50 μm; however, the thickness of the display device is preferably set such that the flexibility of the display device is not reduced in the case where the flexible display device is manufactured. For example, the thickness of the light-transmitting layer is preferably greater than or equal to 10 μm and less than or equal to 30 μm. In addition, the thickness of the light-transmitting layer may be less than 1 μm. 
     Hereinafter, specific examples of the display device of one embodiment of the present invention are described with reference to drawings. 
     Hereinafter, to distinguish the display panels from each other, the same components included in the display panels from each other, or the same components relating to the display panels from each other, letters are added to reference numerals. Unless otherwise specified, “a” is added to reference numerals for a display panel and components placed on the lowest side (the side opposite to the display surface side), and to one or more display panels and components placed thereover, “b”, “c”, and the like are added in alphabetical order from the lower side. Furthermore, unless otherwise specified, in describing a structure in which a plurality of display panels is included, letters are not added when a common part of the display panels or the components is described. 
     The display device of one embodiment of the present invention includes a plurality of display panels in one or more directions. 
       FIG.  1 A  is a top view of a display device  10 . The display device  10  illustrated in  FIG.  1 A  includes three display panels  100  illustrated in  FIG.  2 B  arranged in one direction (a lateral direction). 
       FIGS.  1 B and  1 C  are perspective views of the display device  10  different from that in  FIG.  1 A . The display device  10  in  FIGS.  1 B and  1 C  includes four display panels  100  illustrated in  FIG.  2 C  arranged in a matrix of two rows and two columns (two display panels in the vertical direction and those in the lateral direction).  FIG.  1 B  is a perspective view of the display device  10  on the display surface side.  FIG.  1 C  is a perspective view of the display device  10  on the side opposite to the display surface side. 
       FIGS.  1 A to  1 C  illustrate examples where each of the display panels is electrically connected to an FPC. 
     A display panel which can be used for the display device  10  is described with reference to  FIGS.  2 A to  2 D .  FIGS.  2 A to  2 D  illustrate examples of a top view of the display panel  100 . 
     The display panel  100  includes a display region  101  and a region  102 . Here, the region  102  refers to a portion other than the display region  101  in a top view of the display panel  100 . The region  102  can also be referred to as a non-display region. 
     For example, the display panel  100  may include the frame-like region  102  that surrounds the display region  101  as illustrated in  FIG.  2 A . 
       FIGS.  2 B to  2 D  specifically illustrate the structures of the region  102 . The region  102  includes a region  110  transmitting visible light and a region  120  blocking visible light. The region  110  transmitting visible light and the region  120  blocking visible light are each adjacent to the display region  101 . The region  110  transmitting visible light and the region  120  blocking visible light may each be provided along part of the outer edge of the display region  101 . 
     In the display panel  100  in  FIG.  2 B , the region  110  transmitting visible light is provided along one side of the display region  101 . In the display panel  100  in  FIG.  2 C , the region  110  transmitting visible light is provided along two sides of the display region  101 . The region  110  transmitting visible light may be provided along three or more sides of the display region  101 . The region  110  transmitting visible light is preferably in contact with the display region  101  and provided so as to extend to end portions of the display panel as illustrated in  FIGS.  2 B to  2 D  or the like. 
     In the display panel  100  in  FIGS.  2 B to  2 D , the region  120  blocking visible light is provided along two sides of the display region  101 . The region  120  blocking visible light may be extended close to the end portions of the display panel. 
     Note that a region other than the region  110  transmitting visible light and the region  120  blocking visible light in the region  102  illustrated in  FIGS.  2 B and  2 C  does not necessarily have a visible light transmitting property. For example, the region  110  transmitting visible light may be provided over the entire circumference of the display panel as illustrated in  FIG.  2 D . At least part of the region  110  transmitting visible light may be adjacent to the display region  101 . The region  120  blocking visible light may be partly provided between the region  110  transmitting visible light and the display region  101 . 
     The display region  101  includes a plurality of pixels arranged in matrix and can display an image. One or more display elements are provided in each pixel. As the display element, a light-emitting element such as an organic EL element, an electrophoretic element, a display element with use of a micro electro mechanical system (MEMS), a liquid crystal element, or the like can be used, for example. 
     A material which transmits visible light is used for the region  110  transmitting visible light. For example, the region  110  transmitting visible light may include a substrate, a bonding layer, or the like included in the display panel  100 . The transmittance with respect to visible light of the region  110  transmitting visible light is preferably higher because light extraction efficiency of the display panel under the region  110  transmitting visible light can be increased. For example, in the region  110  transmitting visible light, the transmittance with respect to light in a wavelength range of 450 nm to 700 nm is 70% or more, preferably 80% or more, more preferably 90% or more on the average. 
     In the region  120  blocking visible light, for example, a wiring electrically connected to the pixels (or display elements) included in the display region  101  is provided. In addition to the wiring, driver circuits (such as a scan line driver circuit and a signal line driver circuit) for driving the pixels may be provided. Furthermore, the region  120  blocking visible light may include a terminal electrically connected to the FPC or the like (also referred to as a connection terminal), a wiring electrically connected to the terminal, and the like. 
     Here, the width W of the region  110  transmitting visible light illustrated in  FIGS.  2 B and  2 C  is preferably greater than or equal to 0.5 mm and less than or equal to 150 mm, more preferably greater than or equal to 1 mm and less than or equal to 100 mm, still more preferably greater than or equal to 2 mm and less than or equal to 50 mm. The region  110  transmitting visible light serves as a sealing region, and as the width W of the region  110  transmitting visible light is larger, the distance between the edge of the display panel  100  and the display region  101  can become longer, so that entry of an impurity such as water into the display region  101  from the outside can be suppressed. Note that the width W of the region  110  transmitting visible light corresponds to the shortest distance between the display region  101  and the edge of the display panel  100  in some cases. 
     For example, in the case where an organic EL element is used as the display element, the width W of the region  110  transmitting visible light is set to be greater than or equal to 1 mm, whereby deterioration of the organic EL element can be effectively suppressed, which leads to an improvement in reliability. Note that also in a part other than the region  110  transmitting visible light, the distance between the edge of the display region  101  and the edge of the display panel  100  is preferably in the above range. 
     The display device  10  in  FIG.  1 A  includes a display panel  100   a , a display panel  100   b , and a display panel  100   c.    
     The display panel  100   b  is placed so that part of the display panel  100   b  overlaps an upper side (a display surface side) of the display panel  100   a . Specifically, the region  110   b  transmitting visible light of the display panel  100   b  is provided to overlap the display region  101   a  of the display panel  100   a . The region  120   b  blocking visible light of the display panel  100   b  is provided so as not to overlap the display region  101   a  of the display panel  100   a . A display region  101   b  of the display panel  100   b  is provided to overlap a region  102   a  of the display panel  100   a  and a region  120   a  blocking visible light thereof. 
     Similarly, the display panel  100   c  is placed so that part of the display panel  100   c  overlaps an upper side (a display surface side) of the display panel  100   b . Specifically, the region  110   c  transmitting visible light of the display panel  100   c  is provided to overlap the display region  101   b  of the display panel  100   b . A region  120   c  blocking visible light of the display panel  100   c  is provided so as not to overlap the display region  101   b  of the display panel  100   b . A display region  101   c  of the display panel  100   c  is provided to overlap a region  102   b  of the display panel  100   b  and a region  120   b  blocking visible light of the display panel  100   b.    
     The region  110   b  transmitting visible light is provided to overlap the display region  101   a ; thus, a user of the display device  10  can visually recognize the entire image of the display region  101   a  even when the display panel  100   b  overlaps a display surface of the display panel  100   a . Similarly, the region  110   c  transmitting visible light is provided to overlap the display region  101   b ; thus, a user of the display device  10  can visually recognize the entire image of the display region  101   b  even when the display panel  100   c  overlaps a display surface of the display panel  100   b.    
     The display region  101   b  of the display panel  100   b  is provided to overlap the upper sides of the region  102   a  and the region  120   a  blocking visible light, whereby a non-display region is not provided between the display region  101   a  and the display region  101   b . Similarly, the display region  101   c  of the display panel  100   c  overlaps the upper sides of the region  102   b  and the region  120   b  blocking visible light, whereby a non-display region does not exist between the display region  101   b  and the display region  101   c . Therefore, a region where the display region  101   a , the display region  101   b , and the display region  101   c  are placed seamlessly can serve as the display region  11  of the display device  10 . 
     The display device  10  in  FIGS.  1 B and  1 C  includes the display panel  100   a , the display panel  100   b , the display panel  100   c , and a display panel  100   d.    
     In  FIGS.  1 B and  1 C , short sides of the display panels  100   a  and  100   b  overlap with each other, so that part of the display region  101   a  and part of the region  110   b  transmitting visible light overlap with each other. The long sides of the display panels  100   a  and  100   c  overlap with each other, so that part of the display region  101   a  and part of the region  110   c  transmitting visible light overlap with each other. 
     In  FIGS.  1 B and  1 C , part of the display region  101   b  overlaps with part of the region  110   c  transmitting visible light and part of a region  110   d  transmitting visible light. In addition, part of the display region  101   c  overlaps with part of the region  110   d  transmitting visible light. 
     Therefore, as illustrated in  FIG.  1 B , a region where the display regions  101   a  to  101   d  are placed seamlessly can serve as the display region  11  of the display device  10 . 
     Here, the display panel  100  preferably has flexibility. For example, a pair of substrates included in the display panel  100  preferably has flexibility. 
     Thus, as shown in  FIGS.  1 B and  1 C , a region near an FPC  112   a  of the display panel  100   a  can be bent so that part of the display panel  100   a  and part of the FPC  112   a  can be placed under the display region  101   b  of the display panel  100   b  adjacent to the FPC  112   a . As a result, the FPC  112   a  can be placed without physical interference with the rear surface of the display panel  100   b . Furthermore, when the display panel  100   a  and the display panel  100   b  overlap and are fixed to each other, it is not necessary to consider the thickness of the FPC  112   a ; thus, the difference in height between the top surface of the region  110   b  transmitting visible light and the top surface of the display panel  100   a  can be reduced. This can make an end portion of the display panel  100   b  over the display region  101   a  less noticeable. 
     Moreover, each display panel  100  has flexibility, whereby the display panel  100   b  can be curved gently so that the top surface of the display region  101   b  of the display panel  100   b  and the top surface of the display region  101   a  of the display panel  100   a  are equal to each other in height. Thus, the heights of the display regions can be equal to each other except in the vicinity of the region where the display panel  100   a  and the display panel  100   b  overlap each other, so that the display quality of an image displayed on the display region  11  of the display device  10  can be improved. 
     Although, the relation between the display panel  100   a  and the display panel  100   b  is taken as an example in the above description, the same can apply to the relation between any other two adjacent display panels. 
     Furthermore, to reduce the step between two adjacent display panels  100 , the thickness of the display panel  100  is preferably small. For example, the thickness of the display panel  100  is preferably less than or equal to 1 mm, further preferably less than or equal to 300 μm, still further preferably less than or equal to 100 μm. The display panel is preferably thin because the thickness or weight of the whole display device can also be reduced. 
       FIG.  3 A  is a top view of the display device  10  in  FIGS.  1 B and  1 C  when seen from the display surface side. 
     Here, when the region  110  transmitting visible light of the display panel  100  does not have sufficiently high transmittance with respect to visible light (e.g., light with a wavelength of greater than or equal to 450 nm and less than or equal to 700 nm), luminance of a displayed image may be decreased depending on the number of display panels  100  overlapping the display regions  101 . 
     For example, in a region A in  FIG.  3 A , one display panel  100   c  overlaps the display region  101   a  of the display panel  100   a . In a region B, the two display panels  100  (the display panels  100   c  and  100   d ) overlap the display region  101   b  of the display panel  100   b . In a region C, the three display panels  100  (the display panels  100   b ,  100   c  and  100   d ) overlap the display region  101   a  of the display panel  100   a.    
     In this case, it is preferable that data of the displayed image be corrected so that the gray scale of the pixels is locally increased depending on the number of display panels  100  overlapping the display regions  101 . In this manner, a decrease in the display quality of the image displayed on the display region  11  of the display device  10  can be suppressed. 
     Alternatively, the position of an end portion of the display panel  100  placed on the upper side may be shifted from the positions of end portions of the other display panels  100 , whereby the number of display panels  100  overlapping the display regions  101  of the lower display panels  100  can be reduced. 
     In  FIG.  3 B , the display panels  100   c  and  100   d  placed on the display panels  100   a  and  100   b  are shifted in one direction. Specifically, the display panels  100   c  and  100   d  are relatively shifted from the display panels  100   a  and  100   b  in the X direction by the distance of the width W of the region  110  transmitting visible light. At this time, there are two kinds of regions: a region D in which one display panel  100  overlaps the display region  101 , and a region E in which two display panels  100  overlap the display region  101 . 
     The display panel may be shifted in a direction perpendicular to the X direction (Y direction). In  FIG.  3 C , the display panels  100   b  and  100   d  are relatively shifted from the display panels  100   a  and  100   c  in the Y direction by the distance of the width W of the region  110  transmitting visible light. 
     In the case where the display panel  100  placed on the upper side is shifted from the display  100  placed on the lower side, the shape of the contour of a region in which the display regions  101  of the display panels  100  are combined is different from a rectangular shape. Thus, in the case where the shape of the display region  11  of the display device  10  is set to a rectangular shape as illustrated in  FIG.  3 B or  3 C , the display device  10  may be driven so that no image is displayed on the display regions  101  of the display panels  100  that are placed outside the display region  11 . Here, considering the number of pixels in a region where an image is not displayed, more pixels than the number obtained by dividing the number of all the pixels in the rectangular display region  11  by the number of display panels  100  may be provided in the display region  101  of the display panel  100 . 
     Although the distance of relative shift of each display panel  100  is set to an integral multiple of the width W of the region  110  transmitting visible light in the above example, the distance is not limited thereto, and may be set as appropriate in consideration of the shape of the display panel  100 , the shape of the display region  11  of the display device  10 , in which the display panels  100  are combined, and the like. 
       FIGS.  4 A to  4 F  and  FIGS.  5 A to  5 F  are examples of cross sectional views of the two display panels attached to each other. 
     In  FIGS.  4 A to  4 D , a lower display panel includes the display region  101   a , the region  110   a  transmitting visible light, and the region  120   a  transmitting visible light. The lower display panel is electrically connected to the FPC  112   a . A display panel on the upper side (on a display surface side) includes the display region  101   b , the region  110   b  transmitting visible light, and the region  120   b  blocking visible light. The display panel on the upper side is electrically connected to the FPC  112   b.    
     In  FIG.  4 A , the FPC  112   a  and the FPC  112   b  are connected to the display surface side (front surface) of the lower display panel and the display surface side of the of the upper display panel, respectively. 
     The display region  101   a  overlaps with the region  110   b  transmitting visible light with the light-transmitting layer  103  provided therebetween. Therefore, air can be prevented from entering between the display region  101   a  and the region  110   b  transmitting visible light, so that reflection at the interface due to a difference in refractive index can be suppressed. 
     Accordingly, luminance difference that occurs between part of the display region  101   a  that overlaps with the region  110   b  transmitting visible light and part of the display region  101   a  that does not overlap with the region  110   b  transmitting visible light can be suppressed, so that a seam between the display panels of the display device can be hardly recognized by a user of the display device. In addition, display unevenness or luminance unevenness of the display device can be suppressed. 
     The region  120   a  blocking visible light and the FPC  112   a  overlap the display region  101   b . Therefore, a sufficient area of a non-display region can be secured and a seamless display region can be increased in size, so that a highly reliable large display device can be realized. 
     In  FIG.  4 B , the FPC  112   a  and the FPC  112   b  are connected to the surface (rear surface) side opposite to the display surface of the lower display panel and the surface (rear surface) side opposite to the display surface of the upper display panel, respectively. 
     As illustrated in  FIG.  4 B , the light-transmitting layer  103  may be provided both between the display region  101   a  and the region  110   b  transmitting visible light and between the region  120   a  transmitting visible light and the display region  101   b.    
     When an FPC is connected to a rear surface side of the display panel, the end portion of the lower display panel can be attached to the rear surface of the upper display panel; thus, the attachment area can be increased and the mechanical strength of the attached portion can be increased. 
     As illustrated in  FIG.  4 C , the light-transmitting layer  103  may overlap the region of the display region  101   a  not overlapping with the upper display panel. Furthermore, the region  110   a  transmitting visible light and the light-transmitting layer  103  may overlap with each other. 
     As illustrated in  FIG.  4 D , the region of the upper display panel not overlapping the display region  101   a  and the light-transmitting layer  103  may overlap with each other. 
     For example, as illustrated in  FIG.  4 E , the lower display panel may include a substrate  151   a , a substrate  152   a , and an element layer  153   a , and the upper display panel may include a substrate  151   b , a substrate  152   b , and an element layer  153   b.    
     The element layer  153   a  includes a region  155   a  containing a display element and a region  156   a  including a wiring electrically connected to the display element. The wiring included in the region  156   a  is electrically connected to the FPC  112   a.    
     The element layer  153   b  included in the upper display panel also includes a region  155   b  containing a display element and a region  156   b  including a wiring electrically connected to the display element. The wiring included in the region  156   b  is electrically connected to the FPC  112   b.    
     A light-transmitting layer  103   a  is provided over the substrate  152   a . For example, a stack of the substrate  152   a  and the light-transmitting layer  103   a  can be formed using the above-described attachment film having a stack of an attachment layer and a base material. The substrate  152   b  and the light-transmitting layer  103   b  can have a similar structure to the stack of the substrate  152   a  and the light-transmitting layer  103   a.    
     Here, fine dirt such as dust in air is attached depending on a material of the light-transmitting layer in some cases. In such a case, it is preferable that the region of the display region  101   a  not overlapping with the upper display panel and the light-transmitting layer  103  do not overlap with each other. This makes it possible to prevent unclear display of the display device due to dirt or the like attached to the light-transmitting layer  103 . 
     As illustrated in  FIG.  4 F , the light-transmitting layer  103   a  may be in contact with the substrate  151   a . For example, a stack of the substrate  151   a  and the light-transmitting layer  103   a  can be formed with use of the above described attachment film having a stack of an attachment layer and a base material. The substrate  151   b  and the light-transmitting layer  103   b  can have a similar structure to the stack of the substrate  151   a  and the light-transmitting layer  103   a.    
     In the structure shown in  FIG.  4 F , the light-transmitting layer is not provided on the outermost surface of the display surface of the display device; thus, unclear display of the display device due to dirt or the like attached to the light-transmitting layer  103  can be prevented. In addition, when a light-transmitting layer having attachability is provided on the rear surface of the display device, the display device can be detachably attached to a desired portion by using a surface of the light-transmitting layer which is not in contact with the display panel. 
     Alternatively, as illustrated in  FIGS.  5 A and  5 B , a resin layer  131  which covers front surfaces of the display panel  100   a  and the display panel  100   b  may be provided. Specifically, the resin layer  131  is preferably provided to cover the display regions of the display panels  100   a  and  100   b  and a region where the display panel  100   a  and the display panel  100   b  overlap. 
     By providing the resin layer  131  over the plurality of display panels  100 , the mechanical strength of the display device  10  can be increased. In addition, the resin layer  131  is formed to have a flat surface, whereby the display quality of an image displayed on the display region  11  can be increased. For example, when a coating apparatus such as a slit coater, a curtain coater, a gravure coater, a roll coater, or a spin coater is used, the resin layer  131  with high flatness can be formed. 
     The refractive index of the resin layer  131  is preferably 0.8 to 1.2 times as high as the refractive index of the substrate on the display surface side of the display panel  100 , more preferably 0.9 times to 1.1 times as high as the refractive index of the substrate on the display surface side of the display panel  100 , and still more preferably 0.95 to 1.15 times as high as the refractive index of the substrate on the display surface side of the display panel  100 . Light can be extracted outside more efficiently as the difference in refractive index between the display panel  100  and the resin layer  131  is smaller. In addition, the resin layer  131  with such a refractive index is provided to cover a step portion between the display panel  100   a  and the display panel  100   b , whereby the step portion is not easily recognized visually, and the display quality of an image displayed on the display region  11  can be increased. 
     The resin layer  131  is a layer that transmits visible light. As the resin layer  131 , for example, an organic resin such as an epoxy resin, an aramid resin, an acrylic resin, a polyimide resin, a polyamide resin, or a polyamide-imide resin can be used. 
     Alternatively, as illustrated in  FIGS.  5 C and  5 D , a protective substrate  132  is preferably provided over the display device  10  with the resin layer  131  provided therebetween. Here, the resin layer  131  may serve as a bonding layer for bonding the protective substrate  132  to the display device  10 . With the protective substrate  132 , the surface of the display device  10  can be protected, and moreover, the mechanical strength of the display device  10  can be increased. For the protective substrate  132  in a region overlapping at least the display region  11 , a light-transmitting material is used. Furthermore, the protective substrate  132  in a region other than the region overlapping the display region  11  may have a light-blocking property not to be visually recognized. 
     The protective substrate  132  may have a function of a touch panel. In the case where the display panel  100  is flexible and can be bent, the protective substrate  132  is also preferably flexible. 
     Furthermore, a difference in refractive index between the protective substrate  132  and the substrate on the display surface side of the display panel  100  or the resin layer  131  is preferably less than or equal to 20%, further preferably less than or equal to 10%, still further preferably less than or equal to 5%. 
     As the protective substrate  132 , a plastic substrate that is formed as a film can be used. Examples of the plastic substrate include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), a polyacrylonitrile resin, a polyimide resin, a polymethyl methacrylate resin, a polycarbonate (PC) resin, a polyethersulfone (PES) resin, a polyamide resin (e.g., nylon, aramid), a polycycloolefin resin, a polystyrene resin, a polyamide imide resin, a polyvinyl chloride resin, polyetheretherketone (PEEK) resin, polysulfone (PSF) resin, polyetherimide (PEI) resin, polyarylate (PAR) resin, polybutylene terephthalate (PBT) resin, a polytetrafluoroethylene (PTFE) resin, and a silicone resin. A substrate in which a fibrous body is impregnated with a resin (also referred to as prepreg) or a substrate whose coefficient of linear expansion is reduced by mixing an organic resin with an inorganic filler can also be used. Furthermore, the protective substrate  132  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. Note that the display device or the display panel of one embodiment of the present invention may be attached to an acrylic plate, a glass plate, a wooden plate, a metal plate, or the like. The display surface of the display device or that of the display panel or the surface opposite to the display surface thereof may be attached to these plates (in the case where the display surface is attached to any of these plates, a plate transmitting visible light is used). It is preferable that the display device or the display panel be detachably attached to any of these plates. 
     As the protective substrate  132 , at least one of a polarizing plate, a circular polarizing plate, a retardation plate, an optical film, and the like may be used. 
     As illustrated in  FIG.  5 E , resin layers  133  and protective substrates  134  may be provided on surfaces opposite to the display surfaces of the display panel  100   a  and the display panel  100   b . When the substrate supporting the display panels is provided on the rear surfaces of the display panels, unintended warping or bending of the display panels can be suppressed, whereby the display surface is kept smooth. Thus, the display quality of an image displayed on the display region  11  can be improved. 
     Note that the resin layer  133  and the protective substrate  134 , which are provided on the side opposite to the display surface, do not necessarily have a light-transmitting property, and a material which absorbs or reflects visible light may be used. 
     As illustrated in  FIG.  5 F , the resin layer  131  and the protective substrate  132  may be provided on the front surfaces of the display panels, and the resin layer  133  and the protective substrate  134  may be provided on the rear surface thereof. In this manner, the display panels  100   a  and  100   b  are sandwiched between the two protective substrates, whereby the mechanical strength of the display device  10  can be further increased. 
     It is preferable that the total thickness of the resin layer  131  and the protective substrate  132  be approximately the same as that of the resin layer  133  and the protective substrate  134 . For example, it is preferable that the thicknesses of the resin layers  131  and  133  are substantially equal to each other, and for the protective substrates  132  and  134 , materials having the same thickness be used. In that case, the plurality of display panels  100  can be located at the center of the stack in the thickness direction. For example, when the stack including the display panel  100  is bent, by locating the display panel  100  at the center in the thickness direction, stress in the lateral direction applied to the display panel  100  by bending can be relieved, which prevents the display panel  100  from being damaged. 
     In the case where the thickness of the resin layer and the protective substrate differs between an end portion and a center of the display device, for example, the total thickness of the resin layer  131  and the protective substrate  132  and that of the resin layer  133  and the protective substrate  134  can be compared in the same condition which is appropriately selected from conditions such as the average thickness, the largest thickness, the smallest thickness, or the like. 
     In  FIG.  5 F , the same material is preferably used for the resin layers  131  and  133  because the manufacturing cost can be reduced. Similarly, the same material is preferably used for the protective substrates  132  and  134  because the manufacturing cost can be reduced. 
     As illustrated in  FIGS.  5 E and  5 F , an opening for extracting the FPC  112   a  is preferably provided in the resin layer  133  and the protective substrate  134 , which are located on the rear surface sides of the display panels  100   a  and  100   b . In particular, as illustrated in  FIG.  5 F , by providing the resin layer  133  to cover part of the FPC  112   a , the mechanical strength at a connection portion between the display panel  100   a  and the FPC  112   a  can be increased, and defects such as separation of the FPC  112   a  can be suppressed. Similarly, the resin layer  133  is preferably provided to cover part of the FPC  112   b.    
     Next, a structure example of the display panel  100  is described.  FIG.  6 A  is an example of a top view in which a region P in  FIG.  2 C  is enlarged, and  FIG.  6 B  is an example of a top view in which a region Q in  FIG.  2 C  is enlarged. 
     As illustrated in  FIG.  6 A , in the display region  101 , a plurality of pixels  141  is arranged in matrix. In the case where the display panel  100  capable of full color display with three colors of red, blue, and green is formed, each of the plurality of pixels  141  corresponds to a sub-pixel capable of displaying any of the three colors. Alternatively, a sub-pixel capable of displaying white or yellow in addition to the three colors may be provided. A region including the pixels  141  corresponds to the display region  101 . 
     A wiring  142   a  and a wiring  142   b  are electrically connected to one pixel  141 . The plurality of wirings  142   a  each intersects with the wiring  142   b , and is electrically connected to a circuit  143   a . The plurality of wirings  142   b  is electrically connected to a circuit  143   b . One of the circuits  143   a  and  143   b  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 circuits  143   a  and  143   b  or both of them may be employed. 
     In  FIG.  6 A , a plurality of wirings  145  electrically connected to the circuit  143   a  or the circuit  143   b  is provided. The wiring  145  is electrically connected to an FPC  123  in an unillustrated region and has a function of supplying a signal from the outside to the circuits  143   a  and  143   b.    
     In  FIG.  6 A , a region including the circuit  143   a , the circuit  143   b , the plurality of wirings  145 , and the like corresponds to the region  120  blocking visible light. 
     In  FIG.  6 B , a region outside the pixel  141  provided closest to the end corresponds to the region  110  transmitting visible light. The region  110  transmitting visible light does not include the members blocking visible light, such as the pixel  141 , the wiring  142   a , and the wiring  142   b . Note that in the case where part of the pixel  141 , the wiring  142   a , or the wiring  142   b  transmits visible light, the part of the pixel  141 , the wiring  142   a , or the wiring  142   b  may be provided to extend to the region  110  transmitting visible light. 
     In the case where the width W of the region  110  transmitting visible light varies depending on the display panel, or in the case where the width varies depending on the positions of the same display panel, the shortest length can be referred to as the width W. In  FIG.  6 B , the distance between the pixel  141  and the end portion of the substrate (that is, the width W of the region  110  transmitting visible light) in the vertical direction is the same as that in the horizontal direction, but one embodiment of the present invention is not limited thereto. 
       FIG.  6 C  is a cross-sectional view taken along line A 1 -A 2  in  FIG.  6 B . The display panels  100  include a pair of substrates (a substrate  151  and a substrate  152 ) transmitting visible light. The substrate  151  and the substrate  152  are bonded to each other with a bonding layer  154 . Here, the substrate on which the pixel  141 , the wiring  142   b , and the like are formed is referred to as the substrate  151 . 
     As illustrated in  FIGS.  6 B and  6 C , in the case where the pixel  141  is positioned closest to the end of the display region  101 , the width W of the region  110  transmitting visible light is the distance between the end portion of the substrate  151  or the substrate  152  and the end portion of the pixel  141 . 
     Note that the end portion of the pixel  141  refers to the end portion of the member that is positioned closest to the end and blocks visible light in the pixel  141 . 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  141 , the end portion of the pixel  141  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.  7 A  is an example of a top view in which the region Q is enlarged, and the position of the wiring  142   a  is different from that in  FIG.  6 B .  FIG.  7 B  is a cross-sectional view taken along line B 1 -B 2  in  FIG.  7 A , and  FIG.  7 C  is a cross sectional view taken along line C 1 -C 2  in  FIG.  7 A . 
     As illustrated in  FIGS.  7 A to  7 C , in the case where the wiring  142   a  is positioned closest to the end of the display region  101 , the width W of the region  110  transmitting visible light is the distance between the end portion of the substrate  151  or the substrate  152  and the end portion of the wiring  142   a . In the case where the wiring  142   a  transmits visible light, the region  110  transmitting visible light may include a region where the wiring  142   a  is provided. 
     Here, in the case where the density of pixels provided in the display region  101  of the display panel  100  is high, misalignment may occur when the two display panels  100  are bonded. 
       FIGS.  8 A to  8 C  show a positional relation between the display region  101   a  of the display panel  100   a  provided on the lower side and the display region  101   b  of the display panel  100   b  provided on the upper side, seen from the display surface side.  FIGS.  8 A to  8 C  show the vicinities of the corner portions of the display regions  101   a  and  101   b . Part of the display region  101   a  is covered with the region  110   b  transmitting visible light. 
       FIG.  8 A  shows the case where adjacent pixels  141   a  and  141   b  are relatively deviated in one direction (Y direction). The arrow in the drawing denotes a direction in which the display panel  100   a  is deviated from the display panel  100   b.    
       FIG.  8 B  shows an example in which the adjacent pixels  141   a  and  141   b  are relatively deviated in a vertical direction and a horizontal direction (X direction and Y direction). 
     In the examples of  FIGS.  8 A and  8 B , 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 regions  101   a  and  101   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 two pixels overlap, the data is corrected so that the pixel positioned on a lower side is not driven and the image data is shifted by one column. 
       FIG.  8 C  shows an example in which the pixels  141   a  and  141   b , which should be adjacent, are relatively deviated in one direction (Y 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 X direction. 
     When the plurality of display panels  100  are bonded, in order to suppress misalignment, each of the display panels  100  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  100 , and the projection and the depression may be attached to each other in a region where the two display panels  100  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 region  101  of the display panel  100 . 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. 
     As described above, in the display device of one embodiment of the present invention, the display region of the display panel positioned on the lower side and the region transmitting visible light of the display panel positioned on the upper side overlap with each other. Accordingly, a non-display region between the display regions of two overlapping display panels can be reduced. Furthermore, the light-transmitting layer having a refractive index higher than that of air and transmitting visible light is provided between the display region and the region transmitting visible light. In that case, air can be prevented from entering between the display region and the region transmitting visible light, so that reflection at the interface due to a difference in refractive index can be reduced. Thus, a large display device in which a seam between the display panels is hardly recognized and display unevenness or luminance unevenness is suppressed can be obtained. 
     This embodiment can be combined with any other embodiment as appropriate. 
     Embodiment 2 
     In this embodiment, a light-emitting panel that can be used for the display device of one embodiment of the present invention is described with reference to drawings. 
     Although a light-emitting panel including an organic EL element is mainly described in this embodiment as an example, a panel that can be used for the display device of one embodiment of the present invention is not limited to this example. 
     Specific Example 1 
       FIG.  9 A  is a plan view of a light-emitting panel, and  FIG.  9 C  is an example of a cross-sectional view taken along dashed-dotted line A 1 -A 2  in  FIG.  9 A .  FIG.  9 C  illustrates an example of a cross-sectional view of the region  110  transmitting visible light. The light-emitting panel described in Specific Example 1 is a top-emission light-emitting panel using a color filter method. In this embodiment, the light-emitting panel can have a structure in which sub-pixels of three colors of red (R), green (G), and blue (B) express one color, a structure in which sub-pixels of four colors of R, G, B, and white (W) express one color, a structure in which sub-pixels of four colors of R, G, B, and yellow (Y) express one color, or the like. There is no particular limitation on the color element and colors other than R, G, B, W, and Y may be used. For example, cyan, magenta, or the like may be used. 
     The light-emitting panel illustrated in  FIG.  9 A  includes the region  110  transmitting visible light, a light-emitting portion  804 , a driver circuit portion  806 , and an FPC  808 . The region  110  transmitting visible light is adjacent to the light-emitting portion  804 , and is placed along two sides of the light-emitting portion  804 . 
     The light-emitting panel illustrated in  FIG.  9 C  includes a substrate  701 , a bonding layer  703 , an insulating layer  705 , a plurality of transistors, a conductive layer  857 , an insulating layer  815 , an insulating layer  817 , a plurality of light-emitting elements, an insulating layer  821 , a bonding layer  822 , a coloring layer  845 , a light-blocking layer  847 , an insulating layer  715 , a bonding layer  713 , and a substrate  711 . The bonding layer  822 , the insulating layer  715 , the bonding layer  713 , and the substrate  711  transmit visible light. Light-emitting elements and transistors included in the light-emitting portion  804  and the driver circuit portion  806  are sealed with the substrate  701 , the substrate  711 , and the bonding layer  822 . 
     The light-emitting portion  804  includes a transistor  820  and a light-emitting element  830  over the substrate  701  with the bonding 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 . 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. 
     The light-emitting portion  804  also 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 bonding layer  822 . 
     The insulating layer  815  has an effect of suppressing diffusion of impurities into a semiconductor included in the transistor. 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. 
     The driver circuit portion  806  includes a plurality of transistors over the substrate  701  with the bonding layer  703  and the insulating layer  705  provided therebetween. In  FIG.  9 C , one of the transistors included in the driver circuit portion  806  is illustrated. 
     The insulating layer  705  and the substrate  701  are attached to each other with the bonding layer  703 . The insulating layer  715  and the substrate  711  are attached to each other with the bonding layer  713 . The insulating layer  705  and the insulating layer  715  are preferably highly resistant to moisture, in which case impurities such as water can be prevented from entering the light-emitting element  830  or the transistor  820 , leading to higher reliability of the light-emitting panel. 
     The conductive layer  857  is electrically connected to an external input terminal through which a signal (e.g., a video signal, a clock signal, a start signal, and a reset signal) or a potential from the outside is transmitted to the driver circuit portion  806 . Here, an example is described in which an FPC  808  is provided as the external input terminal. To prevent an increase in the number of fabrication steps, the conductive layer  857  is preferably formed using the same material and step as the electrode or the wiring in the light-emitting portion or the driver circuit portion. Here, an example in which the conductive layer  857  is formed using the same material and step as the electrodes included in the transistor  820  is described. 
     In the light-emitting panel illustrated in  FIG.  9 C , the FPC  808  is positioned over the substrate  711 . A connector  825  is connected to the conductive layer  857  through an opening provided in the substrate  711 , the bonding layer  713 , the insulating layer  715 , the bonding layer  822 , the insulating layer  817 , 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 . In the case where the conductive layer  857  overlaps with the substrate  711 , the conductive layer  857 , the connector  825 , and the FPC  808  can be electrically connected to one another by forming an opening in the substrate  711  (or using a substrate having an opening portion). 
       FIG.  20    is an example of a cross-sectional view of the display device including two light-emitting panels illustrated in  FIG.  9 B  that overlap each other.  FIG.  20    illustrates the display region  101   a  of the lower light-emitting panel (corresponding to the light-emitting portion  804  illustrated in  FIG.  9 B ), the region  120   a  blocking visible light of the lower light-emitting panel (corresponding to the driver circuit portion  806  or the like illustrated in  FIG.  9 B ), the display region  101   b  of an upper light-emitting panel (corresponding to the light-emitting portion  804  illustrated in  FIG.  9 B ), and the region  110   b  transmitting visible light of the upper light-emitting panel (corresponding to the region  110  transmitting visible light illustrated in  FIG.  9 B ). 
     In the display device illustrated in  FIG.  20   , the light-emitting panel positioned on the display surface side (upper side) includes the region  110   b  transmitting visible light adjacent to the display region  101   b . The display region  101   a  of the lower light-emitting panel and the region  110   b  transmitting visible light of the upper light-emitting panel overlap with each other. Therefore, a non-display region between the display regions of the two light-emitting panels overlapping with each other can be reduced or even removed. Accordingly, a large display device in which a seam between light-emitting panels is hardly recognized by a user can be achieved. 
     The display device illustrated in  FIG.  20    includes a light-transmitting layer  103  having a refractive index higher than that of air and transmitting visible light between the display region  101   a  and the region  110   b  transmitting visible light. In that case, air can be prevented from entering between the display region  101   a  and the region  110   b  transmitting visible light, so that the reflection at the interface due to a difference in refractive index can be reduced. In addition, display unevenness or luminance unevenness of the display device can be suppressed. 
     The light-transmitting layer  103  may overlap with the entire surface of the substrate  711  of the lower light-emitting panel or that of the substrate  701  of the upper light-emitting panel, or may overlap with only the display region  101   a  and the region  110   b  transmitting visible light. In addition, the substrate  711  and the light-transmitting layer  103  may be included in the region  120   a  blocking visible light. 
     For example, the stack of the substrate  701  of the upper light-emitting panel and the light-transmitting layer  103  can be formed of an attachment film having a stack of an attachment layer and a base material. 
     Specific Example 2 
       FIG.  9 B  is a plan view of the light-emitting panel, and  FIG.  10 A  is an example of a cross-sectional view taken along dashed-dotted line A 3 -A 4  in  FIG.  9 B . The light-emitting panel described in Specific Example 2 is a top-emission light-emitting panel using a color filter method, which is different from that described in Specific Example 1. Portions different from those in Specific Example 1 will be described in detail here and the descriptions of portions common to those in Specific Example 1 will be omitted. 
       FIG.  9 B  illustrates an example where the region  110  transmitting visible light is provided along three sides of the light-emitting panel. The region  110  transmitting visible light along two sides among the three is adjacent to the light-emitting portion  804 . 
     The light-emitting panel illustrated in  FIG.  10 A  is different from that in  FIG.  9 C  in the following respects. 
     The light-emitting panel illustrated in  FIG.  10 A  includes insulating layers  817   a  and  817   b  and a conductive layer  856  over the insulating layer  817   a . The source electrode or the drain electrode of the transistor  820  and the lower electrode of the light-emitting element  830  are electrically connected to each other through the conductive layer  856 . 
     The light-emitting panel illustrated in  FIG.  10 A  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 light-emitting panel in  FIG.  10 A  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 bonding layer  822 . 
     In addition, in the light-emitting panel in  FIG.  10 A , the substrate  701  differs from the substrate  711  in size. The FPC  808  is located over the insulating layer  715  and does not overlap with the substrate  711 . The connector  825  is connected to the conductive layer  857  through an opening provided in the insulating layer  715 , the bonding layer  822 , the insulating layer  817 , and the insulating layer  815 . Since no opening needs to be provided in the substrate  711 , there is no limitation on the material of the substrate  711 . 
     Note that as illustrated in  FIG.  10 B , the light-emitting element  830  may include 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 a color filter (the coloring layer) and a microcavity structure (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 emission color of the sub-pixel. 
     Specific Example 3 
       FIG.  9 B  is a plan view of a light-emitting panel, and  FIG.  10 C  is an example of a cross-sectional view taken along dashed-dotted line A 3 -A 4  in  FIG.  9 B . The light-emitting panel described in Specific Example 3 is a top-emission light-emitting panel using a separate coloring method. 
     The light-emitting panel in  FIG.  10 C  includes the substrate  701 , the bonding 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 bonding layer  822 , and the substrate  711 . The bonding layer  822  and the substrate  711  transmit visible light. 
     In the light-emitting panel illustrated in  FIG.  10 C , 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 . 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 . 
     Specific Example 4 
       FIG.  9 B  is a plan view of a light-emitting panel, and  FIG.  11 A  is an example of a cross-sectional view taken along dashed-dotted line A 3 -A 4  in  FIG.  9 B . The light-emitting panel described in Specific Example 4 is a bottom-emission light-emitting panel using a color filter method. 
     The light-emitting panel in  FIG.  11 A  includes the substrate  701 , the bonding 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 bonding layer  822 , and the substrate  711 . The substrate  701 , the bonding 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 light-emitting portion  804  includes the transistor  820 , a transistor  824 , and the light-emitting element  830  over the substrate  701  with the bonding layer  703  and the insulating layer  705  provided therebetween. 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.    
     The driver circuit portion  806  includes a plurality of transistors over the substrate  701  with the bonding layer  703  and the insulating layer  705  provided therebetween. In  FIG.  11 A , two of the transistors included in the driver circuit portion  806  are illustrated. 
     The insulating layer  705  and the substrate  701  are attached to each other with the bonding layer  703 . 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 light-emitting panel. 
     The conductive layer  857  is electrically connected to an external input terminal through which a signal or a potential from the outside is transmitted to the driver circuit portion  806 . Here, an example is described in which an FPC  808  is provided as the external input terminal. 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 . 
     Specific Example 5 
       FIG.  11 B  illustrates an example of a light-emitting panel that is different from those in Specific Examples 1 to 4. 
     A light-emitting panel in  FIG.  11 B  includes the substrate  701 , the bonding layer  703 , the insulating layer  705 , a conductive layer  814 , a conductive layer  857   a , a conductive layer  857   b , the light-emitting element  830 , the insulating layer  821 , the bonding layer  822 , and the substrate  711 . 
     The conductive layer  857   a  and the conductive layer  857   b , which are external connection electrodes of the light-emitting panel, can each be electrically connected to an FPC or the like. 
     The light-emitting element  830  includes the lower electrode  831 , the EL layer  833 , and the upper electrode  835 . An end portion of the lower electrode  831  is covered with the insulating layer  821 . The light-emitting element  830  is a bottom-emission, top-emission, or dual-emission light-emitting element. An electrode, a substrate, an insulating layer, and the like on the light extraction side transmit visible light. The conductive layer  814  is electrically connected to the lower electrode  831 . 
     The substrate through which light is extracted may have, as a light extraction structure, a hemispherical lens, a micro lens array, a film provided with an uneven surface structure, a light diffusing film, or the like. For example, a substrate having the light extraction structure can be formed by bonding the above lens or film to a resin substrate with an adhesive or the like having substantially the same refractive index as the substrate or the lens or film. 
     The conductive layer  814  is preferably, though not necessarily, provided because voltage drop due to the resistance of the lower electrode  831  can be prevented. In addition, for a similar purpose, a conductive layer electrically connected to the upper electrode  835  may be provided over the insulating layer  821 , the EL layer  833 , the upper electrode  835 , or the like. 
     The conductive layer  814  can be a single layer or a stacked layer formed using a material selected from copper, titanium, tantalum, tungsten, molybdenum, chromium, neodymium, scandium, nickel, or aluminum; an alloy material containing any of these materials as its main component; or the like. The thickness of the conductive layer  814  can be, for example, greater than or equal to 0.1 μm and less than or equal to 3 μm, preferably greater than or equal to 0.1 μm and less than or equal to 0.5 μm. 
     &lt;Examples of Materials&gt; 
     Next, materials and the like that can be used for a light-emitting panel are described. Note that description on the components already described in this specification 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 on the side from which light from the light-emitting element is extracted is formed using a material which transmits the light. 
     It is particularly preferable to use a flexible substrate. For example, an organic resin; a glass material, a metal, or an alloy that is thin enough to have flexibility; or the like 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 light-emitting panel can be more lightweight compared with the case where glass is used. 
     The substrates are preferred to be formed using a material with high toughness. In that case, a light-emitting panel with high impact resistance that is less likely to be broken can be provided. For example, when an organic resin substrate, a thin metal substrate, or a thin alloy substrate is used, the light-emitting panel can be lighter and more robust than the case where a glass substrate is used. 
     A metal material and an alloy material, which have high thermal conductivity, are preferred because they can easily conduct heat to the whole substrate and accordingly can prevent a local temperature rise in the light-emitting 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, 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 light-emitting panel can be prevented from rising, leading to prevention of breakage or a decrease in reliability of the light-emitting panel. For example, the substrate may have a stacked-layer structure of a metal substrate and a layer with high thermal emissivity (e.g., the layer can be formed using a metal oxide or a ceramic material). 
     Examples of materials having flexibility and a light-transmitting property include a material used for the protective substrate  132  described in Embodiment 1. 
     The flexible substrate may have a stacked-layer structure in which a hard coat layer (such as a silicon nitride layer) by which a surface of a light-emitting device is protected from damage, a layer (such as an aramid resin layer) which can disperse pressure, 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 reliable light-emitting panel can be provided. 
     A flexible substrate in which a glass layer, a bonding layer, and an organic resin layer are stacked from the side closer to a light-emitting element is preferably 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 a 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. Providing such organic resin layer outside the glass layer, occurrence of a crack or a break in the glass layer can be suppressed 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 and flexible light-emitting panel can be provided. 
     Any of a variety of curable adhesives, e.g., light curable adhesives such as a UV curable adhesive, a reactive curable adhesive, a thermal curable adhesive, and an anaerobic adhesive can be used for the adhesive layer. Examples of these adhesives 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, and an ethylene vinyl acetate (EVA) resin. In particular, a material with low moisture permeability, such as an epoxy resin, is preferred. Alternatively, a two-component-mixture-type resin may be used. Further alternatively, an adhesive sheet or the like may be used. 
     Further, the resin may include a drying agent. For example, a substance that adsorbs moisture by chemical adsorption, such as 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 because it can prevent an impurity such as moisture from entering the functional element, thereby improving the reliability of the light-emitting panel. 
     In addition, it is preferable to mix a filler with a high refractive index or light-scattering member 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, a silicon nitride oxide film, or the like), a film containing nitrogen and aluminum (e.g., an aluminum nitride film or the like), 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 moisture vapor transmission rate of the insulating film highly resistant to moisture is lower than or equal to 1×10 − 5 [g/(m2·day)], preferably lower than or equal to 1×10 − 6 [g/(m2·day)], further preferably lower than or equal to 1×10 − 7 [g/(m2·day)], still further preferably lower than or equal to 1×10 − 8 [g/(m2·day)]. 
     In the light-emitting panel, it is necessary that at least one of the insulating layers  705  and  715  transmit light emitted from the light-emitting element. One of the insulating layers  705  and  715 , which transmits light emitted from the light-emitting element, preferably has higher average transmittance of light having a wavelength of greater than or equal to 400 nm and less than or equal to 800 nm than the other. 
     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 light-emitting 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 have a light-transmitting property. 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 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 light-emitting device. Specifically, the use of an insulating film having high resistance to moisture for the insulating layer  705  and the insulating layer  715  allows the light-emitting element to be located between a pair of insulating films having high resistance to moisture, by which decrease in reliability of the light-emitting device can be prevented. 
     As the insulating layer  815 , for example, an inorganic insulating film such as a silicon oxide film, a silicon oxynitride film, or an aluminum oxide film can be used. For example, 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. 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 to have an opening over the lower electrode  831  and an inclined side wall with curvature, using a photosensitive resin material. 
     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 light-emitting device, 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 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 light-emitting 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 bonding layer, a material which has high wettability with respect to the material of the bonding 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. 
     As described above, a variety of panels such as a light-emitting panel, a display panel, and a touch panel can be used in the display device of one embodiment of the present invention. 
     Note that the light-emitting panel of one embodiment of the present invention may be used as a display device 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 device for a display panel. 
     As described above, with a light-emitting panel including a region transmitting visible light described in this embodiment, a large display device in which a seam between light-emitting panels is hardly recognized and display unevenness is suppressed can be obtained. 
     This embodiment can be combined with any other embodiment as appropriate. 
     Embodiment 3 
     In this embodiment, a flexible display panel that can be used for the display device of one embodiment of the present invention is described with reference to drawings. Note that the above description can be referred to for the components of a touch panel, which are similar to those of the light-emitting panel described in Embodiment 2. Although a touch panel including a light-emitting element is described in this embodiment as an example, one embodiment of the present invention is not limited to this example. 
     Structure Example 1 
       FIG.  12 A  is a top view of the touch panel.  FIG.  12 B  is a cross-sectional view taken along dashed-dotted line A-B and dashed-dotted line C-D in  FIG.  12 A .  FIG.  12 C  is a cross-sectional view taken along dashed-dotted line E-F in  FIG.  12 A . 
     A touch panel  390  illustrated in  FIG.  12 A  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 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.  12 B and  12 C , the touch panel  390  includes the substrate  701 , the bonding layer  703 , the insulating layer  705 , the substrate  711 , the bonding layer  713 , and the insulating layer  715 . The substrates  701  and  711  are bonded to each other with a bonding layer  360 . 
     The substrate  701  and the insulating layer  705  are attached to each other with the bonding layer  703 . The substrate  711  and the insulating layer  715  are attached to each other with the bonding layer  713 . 
     Embodiment 2 can be referred to for materials used for the substrates, the bonding 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 ( FIG.  12 C ). 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.  12 C ). 
     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 a bonding 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 bonding layer  360  and 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.  12 C . 
     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 planarizing unevenness caused by the pixel circuits and the imaging pixel circuits. An insulating layer that can inhibit diffusion of impurities to the transistor  302   t  and the like 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. 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.  12 B , 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 . 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 . 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.  13 A and  13 B  are perspective views of a touch panel  505 .  FIGS.  13 A and  13 B  illustrate only main components for simplicity.  FIGS.  14 A to  14 C  are each a cross-sectional view taken along the dashed-dotted line X 1 -X 2  in  FIG.  13 A . 
     As illustrated in  FIGS.  13 A and  13 B , the touch panel  505  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  includes the substrate  701 , the substrate  711 , and a substrate  590 . 
     The touch panel  505  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 arranged 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  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 arranged 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.  13 B , 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 are 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 preferable 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.  13 A and  13 B . 
     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 . A 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. 
     As illustrated in  FIG.  14 A , the touch panel  505  includes the substrate  701 , the bonding layer  703 , the insulating layer  705 , the substrate  711 , the bonding layer  713 , and the insulating layer  715 . The substrates  701  and  711  are bonded to each other with a bonding layer  360 . 
     A bonding layer  597  attaches the substrate  590  to the substrate  711  so that the touch sensor  595  overlaps with the display portion  501 . The bonding layer  597  has a light-transmitting property. 
     The electrodes  591  and the electrodes  592  are formed using a light-transmitting conductive material. 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. 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, heating 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. Examples of such a metal nanowire include an Ag nanowire, a Cu nanowire, and an Al nanowire. In the case of using an Ag nanowire, 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. 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  592  can be favorably used as the wiring  594  because electric resistance can be reduced. 
     Note that an insulating layer that covers 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 wiring  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.  14 A and  14 B . 
     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.  14 A . 
     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.  14 B . 
     A structure in the case of using top-gate transistors is illustrated in  FIG.  14 C . 
     For example, a semiconductor layer containing 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.  14 C . 
     Structure Example 3 
       FIGS.  15 A to  15 C  are cross-sectional views of a touch panel  505 B. The touch panel  505 B described in this embodiment is different from the input-output device  505  in Structure Example 2 in that received image data is displayed on the side where the transistors are provided and that the touch sensor is provided on the substrate  701  side of the display portion. 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.  15 A  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.  15 A . 
     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.  15 A ). 
     The bonding layer  597  attaches the substrate  590  to the substrate  701  so that the touch sensor  595  overlaps with the display portion. The bonding layer  597  has a light-transmitting property. 
     Note that a structure in the case of using bottom-gate transistors in the display portion  501  is illustrated in  FIGS.  15 A and  15 B . 
     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.  15 A . 
     For example, a semiconductor layer containing polycrystalline silicon can be used in the transistor  302   t  and the transistor  303   t  illustrated in  FIG.  15 B . 
     A structure in the case of using top-gate transistors is illustrated in  FIG.  15 C . 
     For example, a semiconductor layer containing polycrystalline silicon, a transferred single crystal silicon film, or the like can be used in the transistor  302   t  and the transistor  303   t  illustrated in  FIG.  15 C . 
     Structure Example 4 
     As illustrated in  FIG.  16   , the touch panel  500 TP includes a display portion  500  and an input portion  600  that overlap each other.  FIG.  17    is a cross-sectional view taken along the dashed-dotted line Z 1 -Z 2  in  FIG.  16   . 
     Components of the touch panel  500 TP are described below. Note that these units can not be clearly distinguished and one unit also serves as another unit or include part of another unit 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 G 1 , a control line RES, a signal line DL, and the like. 
     The selection signal line G 1  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.  16   ). 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.  16   ). 
     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 air, such as a finger, comes close to a conductive film in 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 G 1 , 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.  17 A ). 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 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 . 
     The touch panel  500 TP 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 input-output device  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 input-output device  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 FPC 1 . 
     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 G 1  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  602 . 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 FPC 1  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 (or driver circuit) may be electrically connected to an FPC 2 . 
     In addition, a protective layer  670  that prevents damage and protects the input-output device  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. 
     This embodiment can be combined with any other embodiment as appropriate. 
     Embodiment 4 
     In this embodiment, electronic devices and lighting devices of one embodiment of the present invention will be described with reference to drawings. 
     Examples of electronic devices include a television set (also referred to as a television or a television receiver), a monitor of a computer or the like, a digital camera, a digital video camera, a digital photo frame, a mobile phone (also referred to as a mobile phone device), a portable game machine, a portable information terminal, an audio reproducing device, a large game machine such as a pinball machine, and the like. 
     The electronic device or the lighting device of one embodiment of the present invention has flexibility and therefore can be incorporated along a curved inside/outside wall surface of a house or a building or a curved interior/exterior surface of a car. 
     Furthermore, the electronic device of one embodiment of the present invention may include a secondary battery. It is preferable that the secondary battery be capable of being charged by non-contact power transmission. 
     Examples of the secondary battery include a lithium ion secondary battery such as a lithium polymer battery using a gel electrolyte (lithium ion polymer battery), a nickel-hydride battery, a nickel-cadmium battery, an organic radical battery, a lead-acid battery, an air secondary battery, a nickel-zinc battery, and a silver-zinc battery. 
     The electronic device of one embodiment of the present invention may include an antenna. When a signal is received by the antenna, the electronic device can display an image, data, or the like on a display portion. When the electronic device includes a secondary battery, the antenna may be used for contactless power transmission. 
     In the display device of one embodiment of the present invention, by increasing the number of display panels, the area of the display region can be increased unlimitedly. Thus, the display device can be favorably used for applications such as digital signage and a PID. Furthermore, by changing the arrangement of the display panels, the contour of the display device of one embodiment of the present invention can have any of a variety of shapes. 
       FIG.  18 A  shows an example in which the display device  10  of one embodiment of the present invention is provided for a column  15  and a wall  16 . A flexible display panel is used as the display panel  100  included in the display device  10 , whereby the display device  10  can be placed along a curved surface. 
     Here, in particular, in the case where the display device of one embodiment of the present invention is used in digital signage and a PID, it is preferable to use a touch panel in a display panel because a device with such a structure can be operated by viewers intuitively as well as displaying a still or moving image on a display region. Alternatively, in the case where the display device of one embodiment of the present invention is used for providing information such as route information and traffic information, usability can be enhanced by intuitive operation. In the case of providing the display device on the walls of buildings, public facilities, and the like, a touch panel is not necessarily used in the display panel. 
       FIGS.  18 B to  18 E  illustrate an example of an electronic device including the display portion  7000  with a curved surface. The display surface of the display portion  7000  is bent, and images can be displayed on the bent display surface. The display portion  7000  may be flexible. 
     The display portion  7000  of each of the electronic devices illustrated in  FIGS.  18 B to  18 E  can be formed using the display device of one embodiment of the present invention. 
       FIG.  18 B  illustrates an example of a mobile phone. A mobile phone  7100  includes a housing  7101 , the display portion  7000 , operation buttons  7103 , an external connection port  7104 , a speaker  7105 , a microphone  7106 , and the like. 
     The mobile phone  7100  illustrated in  FIG.  18 B  includes a touch sensor in the display portion  7000 . Moreover, operations such as making a call and inputting a letter can be performed by touch on the display portion  7000  with a finger, a stylus, or the like. 
     With the operation buttons  7103 , power ON or OFF can be switched. In addition, types of images displayed on the display portion  7000  can be switched; switching images from a mail creation screen to a main menu screen, for example. 
       FIG.  18 C  illustrates an example of a television set. In a television set  7200 , the display portion  7000  is incorporated into the housing  7201 . Here, the housing  7201  is supported by a stand  7203 . 
     The television set  7200  illustrated in  FIG.  18 C  can be operated with an operation switch of the housing  7201  or a separate remote controller  7211 . Furthermore, the display portion  7000  may include a touch sensor. The display portion  7000  can be performed by touching the display portion with a finger or the like. Furthermore, the remote controller  7211  may be provided with a display portion for displaying data output from the remote controller  7211 . With operation keys or a touch panel of the remote controller  7211 , channels and volume can be controlled and images displayed on the display portion  7000  can be controlled. 
     Note that the television set  7200  is provided with a receiver, a modem, and the like. A general television broadcast can be received with the receiver. Further, when the television set is connected to a communication network with or without wires via the modem, one-way (from a transmitter to a receiver) or two-way (between a transmitter and a receiver or between receivers) data communication can be performed. 
       FIG.  18 D  illustrates an example of a portable information terminal. A portable information terminal  7300  includes a housing  7301  and the display portion  7000 . Each of the portable information terminals may also include an operation button, an external connection port, a speaker, a microphone, an antenna, a battery, or the like. The display portion  7000  is provided with a touch sensor. An operation of the portable information terminal  7300  can be performed by touching the display portion  7000  with a finger, a stylus, or the like. 
       FIG.  18 D  is a perspective view of the portable information terminal  7300 .  FIG.  18 E  is a top view of the portable information terminal  7300 . 
     Each of the portable information terminals illustrated in this embodiment functions as, for example, one or more of a telephone set, a notebook, and an information browsing system. Specifically, each of the portable information terminals can be used as a smartphone. Each of the portable information terminals illustrated in this embodiment is capable of executing a variety of applications such as mobile phone calls, e-mailing, reading and editing texts, music reproduction, Internet communication, and a computer game, for example. 
     The portable information terminal  7300  can display characters and image information on its plurality of surfaces. For example, as illustrated in  FIG.  18 D , three operation buttons  7302  can be displayed on one surface, and information  7303  indicated by a rectangle can be displayed on another surface.  FIGS.  18 D and  18 E  illustrate an example in which information is displayed at the top of the portable information terminal. Alternatively, information may be displayed on the side of the portable information terminal. Information may also be displayed on three or more surfaces of the portable information terminal. 
     Examples of the information include notification from a social networking service (SNS), display indicating reception of an e-mail or an incoming call, the title of an e-mail or the like, the sender of an e-mail or the like, the date, the time, remaining battery, and the reception strength of an antenna. Alternatively, the operation button, an icon, or the like may be displayed in place of the information. 
     For example, a user of the portable information terminal  7300  can see the display (here, the information  7303 ) with the portable information terminal  7300  put in a breast pocket of his/her clothes. 
     Specifically, a caller&#39;s phone number, name, or the like of an incoming call is displayed in a position that can be seen from above the portable information terminal  7300 . Thus, the user can see the display without taking out the portable information terminal  7300  from the pocket and decide whether to answer the call. 
       FIG.  18 F  illustrates an example of a lighting device having a curved light-emitting portion. 
     The light-emitting portion included in the lighting devices illustrated in  FIG.  18 F  can be manufactured using the display device of one embodiment of the present invention. 
     A lighting device  7400  illustrated in  FIG.  18 F  includes a light-emitting portion  7402  having a wave-shaped light-emitting surface, which is a good-design lighting device. 
     The light-emitting portion included in the lighting device  7400  may be flexible. The light-emitting portion may be fixed on a plastic member, a movable frame, or the like so that an emission surface of the light-emitting portion can be bent freely depending on the intended use. 
     The lighting device  7400  includes a stage  7401  provided with an operation switch  7403  and a light-emitting portion supported by the stage  7401 . 
     Note that although the lighting device in which the light-emitting portion is supported by the stage is described as an example here, a housing provided with a light-emitting portion can be fixed on a ceiling or suspended from a ceiling. Since the light-emitting surface can be curved, the light-emitting surface is curved to have a depressed shape, whereby a particular region can be brightly illuminated, or the light-emitting surface is curved to have a projecting shape, whereby a whole room can be brightly illuminated. 
     FIGS.  19 A 1 ,  19 A 2 ,  19 B,  19 C,  19 D,  19 E,  19 F,  19 G,  19 H, and  19 I each illustrate an example of a portable information terminal including a display portion  7001  having flexibility. 
     The display portion  7001  is manufactured using the display device of one embodiment of the present invention. For example, a display device that can be bent with a radius of curvature of greater than or equal to 0.01 mm and less than or equal to 150 mm can be used. The display portion  7001  may include a touch sensor so that the portable information terminal can be operated by touching the display portion  7001  with a finger or the like. 
     FIGS.  19 A 1  and  19 A 2  are a perspective view and a cross-sectional view, respectively, illustrating an example of the portable information terminal. A portable information terminal  7500  includes a housing  7501 , the display portion  7001 , a display portion pull  7502 , operation buttons  7503 , and the like. 
     The portable information terminal  7500  includes a rolled flexible display portion  7001  in the housing  7501 . 
     The portable information terminal  7500  can receive a video signal with a control portion incorporated therein and can display the received video on the display portion  7001 . The portable information terminal  7500  incorporates a battery. A terminal portion for connecting a connector may be included in the housing  7501  so that a video signal or power can be directly supplied from the outside with a wiring. 
     By pressing the operation buttons  7503 , power ON/OFF, switching of displayed videos, and the like can be performed. Although FIGS.  19 A 1 ,  19 A 2 , and  19 B illustrate an example where the operation buttons  7503  are positioned on a side surface of the portable information terminal  7500 , one embodiment of the present invention is not limited thereto. The operation buttons  7503  may be placed on a display surface (a front surface) or a rear surface of the portable information terminal  7500 . 
       FIG.  19 B  illustrates the portable information terminal  7500  in a state where the display portion  7001  is pulled out. Videos can be displayed on the display portion  7001  in this state. In addition, the portable information terminal  7500  may perform different displays in the state where part of the display portion  7001  is rolled as shown in FIG.  19 A 1  and in the state where the display portion  7001  is pulled out with the display portion pull  7502  as shown in  FIG.  19 B . For example, in the state shown in FIG.  19 A 1 , the rolled portion of the display portion  7001  is put in a non-display state, which results in a reduction in power consumption of the portable information terminal  7500 . 
     Note that a reinforcement frame may be provided for a side portion of the display portion  7001  so that the display portion  7001  has a flat display surface when pulled out. 
     Note that in addition to this structure, a speaker may be provided for the housing so that sound is output with an audio signal received together with a video signal. 
       FIGS.  19 C to  19 E  illustrate an example of a foldable portable information terminal.  FIG.  19 C  illustrates a portable information terminal  7600  that is opened.  FIG.  19 D  illustrates the portable information terminal  7600  that is being opened or being folded.  FIG.  19 E  illustrates the portable information terminal  7600  that is folded. The portable information terminal  7600  is highly portable when folded, and is highly browsable when opened because of a seamless large display area. 
     A display portion  7001  is supported by three housings  7601  joined together by hinges  7602 . By folding the portable information terminal  7600  at a connection portion between two housings  7601  with the hinges  7602 , the portable information terminal  7600  can be reversibly changed in shape from an opened state to a folded state. 
       FIGS.  19 F and  19 G  illustrate an example of a foldable portable information terminal.  FIG.  19 F  illustrates a portable information terminal  7650  that is folded so that the display portion  7001  is on the inside.  FIG.  19 G  illustrates the portable information terminal  7650  that is folded so that the display portion  7001  is on the outside. The portable information terminal  7650  includes the display portion  7001  and a non-display portion  7651 . When the portable information terminal  7650  is not used, the portable information terminal  7650  is folded so that the display portion  7001  is on the inside, whereby the display portion  7001  can be prevented from being contaminated or damaged. 
       FIG.  19 H  illustrates an example of a flexible portable information terminal. The portable information terminal  7700  includes a housing  7701  and the display portion  7001 . In addition, the portable information terminal  7700  may include buttons  7703   a  and  7703   b  which serve as input means, speakers  7704   a  and  7704   b  which serve as sound output means, an external connection port  7705 , a microphone  7706 , or the like. A flexible battery  7709  can be mounted on the portable information terminal  7700 . The battery  7709  may be arranged to overlap with the display portion  7001 , for example. 
     The housing  7701 , the display portion  7001 , the battery  7709  are flexible. Thus, it is easy to curve the portable information terminal  7700  into a desired shape or to twist the portable information terminal  7700 . For example, the portable information terminal  7700  can be curved so that the display portion  7001  is on the inside or in the outside. The portable information terminal  7700  can be used in a rolled state. Since the housing  7701  and the display portion  7001  can be transformed freely in this manner, the portable information terminal  7700  is less likely to be broken even when the portable information terminal  7700  falls down or external stress is applied to the portable information terminal  7700 . 
     The portable information terminal  7700  can be used effectively in various situations because the portable information terminal  7700  is lightweight. For example, the portable information terminal  7700  can be used in the state where the upper portion of the housing  7701  is suspended by a clip or the like, or in the state where the housing  7701  is fixed to a wall by magnets or the like. 
       FIG.  19 I  illustrates an example of a wrist-watch-type portable information terminal. The portable information terminal  7800  includes a band  7801 , the display portion  7001 , an input-output terminal  7802 , operation buttons  7803 , or the like. The band  7801  has a function of a housing. A flexible battery  7805  can be mounted on the portable information terminal  7800 . The battery  7805  may overlap with the display portion  7001  and the band  7801 , for example. 
     The band  7801 , the display portion  7001 , and the battery  7805  have flexibility. Thus, the portable information terminal  7800  can be easily curved to have a desired shape. 
     With the operation button  7803 , a variety of functions such as time setting, ON/OFF of the power, ON/OFF of wireless communication, setting and cancellation of manner mode, and setting and cancellation of power saving mode can be performed. For example, the functions of the operation button  7803  can be set freely by the operating system incorporated in the portable information terminal  7800 . 
     By touching an icon  7804  displayed on the display portion  7001  with a finger or the like, application can be started. 
     The portable information terminal  7800  can employ near field communication that is a communication method based on an existing communication standard. In that case, for example, mutual communication between the portable information terminal  7800  and a headset capable of wireless communication can be performed, and thus hands-free calling is possible. 
     The portable information terminal  7800  may include the input-output terminal  7802 . In the case where the input-output terminal  7802  is included, data can be directly transmitted to and received from another information terminal via a connector. Charging through the input-output terminal  7802  is also possible. Note that charging of the portable information terminal described as an example in this embodiment can be performed by non-contact power transmission without using the input-output terminal. 
     This embodiment can be combined with any other embodiment as appropriate. 
     Example 1 
     In this example, the results of manufacturing the display device of one embodiment of the present invention are described. The method for manufacturing the display device used in this example is similar to that for manufacturing a Japanese traditional roof with tiles (kawara in Japanese). Thus, a multidisplay manufactured by overlapping a plurality of display panels as in the display device manufactured in this example is referred to as a “kawara-type multidisplay” in some cases. 
       FIGS.  21 A and  21 B  illustrate a display device manufactured in this example.  FIG.  21 A  is a photograph of the opposite side to the display surface of the display device.  FIG.  21 B  is a photograph of the display surface side of the display device displaying an image. 
     The display device illustrated in  FIGS.  21 A and  21 B  includes four display panels arranged in a matrix of two rows and two columns. Specifically, the display device includes the display panels  100   a ,  100   b ,  100   c , and  100   d.    
       FIG.  22 A  is a schematic view of the display panel. A light-emitting portion  250  in the display panel has a size of 3.4 inches diagonal, 960×540×RGB effective pixels, a resolution of 326 ppi, and an aperture ratio of 44.4%. The display panel includes a demultiplexer (DeMUX)  253  serving as a source driver. In addition, the display panel also includes a scan driver  255 . The display panel is an active matrix organic EL display, and a pixel circuit includes three transistors and a capacitor. Two sides of the light-emitting portion  250  are in contact with a region  251  transmitting visible light. A lead wiring  257  is provided along the other two sides. 
       FIG.  21 C  is a cross-sectional schematic view of the display panels  100   a  and  100   b  attached to each other in the display device. 
     The display device illustrated in  FIGS.  21 A to  21 C  is different from the display device illustrated in  FIG.  4 F  in that a bonding layer  157  is included and a light-transmitting layer is provided on the display surface side of the display panel. 
     Each of the display panels has light-transmitting layers on both the display surface and a surface opposite to the display surface. For example, as illustrated in  FIG.  21 C , the display panel  100   a  has a light-transmitting layer  103   a   1  on the display surface side and a light-transmitting layer  103   a   2  on the surface opposite to the display surface. The display panel  100   b  has a light-transmitting layer  103   b   1  on the display surface side and a light-transmitting layer  103   b   2  on the surface opposite to the display surface. In this example, an attachment film having a stack of an attachment layer and a base material was used as each of the light-transmitting layers. 
     Each of the display panels was formed by attaching a substrate and an element layer with a bonding layer. For example, as illustrated in  FIG.  21 C , the substrate  151   a , the substrate  152   a , the substrate  151   b , and the substrate  152   b  are attached to the element layer  153   a , the element layer  153   a , the element layer  153   b , and the element layer  153   b  respectively, with the bonding layer  157 . 
     The display device in this example is formed by overlapping four display panels so that a non-display region between display regions is made small. Specifically, the region transmitting visible light of one display panel overlaps the display region of another display panel with the light-transmitting layer provided therebetween. Accordingly, a large display device in which a seam between the display panels is hardly recognized by a user can be obtained (see  FIG.  21 B ). 
     Because the display panel has attachment layers on both the display surface and the surface opposite to the display surface, both sides of the display device can be attached to or fixed to a flat surface. For example, the surface opposite to the display surface of the display device can be attached to a wall. In addition, the display surface of the display device can be attached to a transparent plate such as a glass substrate. The attachment layer can prevent the display surface of the display device from being damaged and the display device from being bent, whereby display visibility can be improved. 
     The four display panels have flexibility. Thus, as illustrate in  FIGS.  21 A and  21 C , a region near the FPC  112   a  of the display panel  100   a  can be bent so that part of the display panel  100   a  and part of the FPC  112   a  can be placed under the display region of the display panel  100   b  adjacent to the FPC  112   a . As a result, the FPC  112   a  can be placed without physical interference with the rear surface of the display panel  100   b.    
     Since the attachment film having a stack of an attachment layer and a base material is used, each of the display panels can be detachably attached to another display panel included in the display device. 
     The structure of the display panels  100   a  to  100   d  illustrated in  FIG.  21 A  corresponds to that of the light-emitting panel illustrated in  FIGS.  10 A and  10 B  except the following points. First, each of the display panels  100   a  to  100   d  does not include the insulating layer  817   b  and the conductive layer  856 , and the source electrode or the drain electrode of the transistor  820  and the lower electrode  831  of the light-emitting element  830  are directly connected to each other. Second, each of the display panels  100   a  to  100   d  does not include the light-blocking layer  847 . For the structure of the light-emitting element  830  of each of the display panels  100   a  to  100   d ,  FIG.  10 B  can be referred to. 
     In this example, as the light-emitting element, a tandem (stack) organic EL element emitting white light is 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. Moreover, since the CAAC-OS does not have a grain boundary, a stable and uniform film can be formed over a large area, and stress that is caused by bending a flexible display panel or a display device does not easily make a crack in a CAAC-OS film. 
     A CAAC-OS is a crystalline oxide semiconductor having c-axis alignment of crystals 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 the 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. 
     Here,  FIG.  22 B  illustrates the stacked-layer structure of the region  110  transmitting visible light in the display panel used in this example. 
     As illustrated in  FIG.  22 B , in the region  110  transmitting visible light, the substrate  701 , the bonding layer  703 , the insulating layer  705 , a gate insulating layer  813 , the insulating layer  815 , the bonding layer  822 , the insulating layer  715 , the bonding layer  713 , and the substrate  711  are stacked in this order. As the visible light transmittance of the region  110  transmitting visible light is higher, the efficiency of light extraction of the display device can be increased. In this example, the kind and the thickness of an inorganic insulating film in the stacked-layer structure were optimized by means of an optical simulation to improve the transmittance with respect to light. 
     At the optical simulation, in order to ensure the favorable characteristics (or reliability) of the transistor, the kinds and the thicknesses of the gate insulating layer  813  and the insulating layer  815  serving as a protective film of the transistor were not changed. Since only the region  110  transmitting visible light of these films can be opened, formation of only part of a layer included in the gate insulating layer  813  or the insulating layer  815  was allowed. 
     Specifically, although the insulating layer  815  has a stacked-layer structure of a silicon oxynitride film and a silicon nitride film in the light-emitting portion or the like, the silicon nitride film was not provided in the region  110  transmitting visible light based on the calculation results. 
     The display panel in this example was formed in such a manner that a layer to be separated was formed over a formation substrate with a separation layer provided therebetween, separated from the formation substrate, and then transferred to another substrate. 
     Therefore, to secure the separability, the kinds and the thicknesses of a layer in contact with the separation layer included in the insulating layer  705  (a layer included in the insulating layer  705  which is in contact with the bonding layer  703  in the display panel) and a layer in contact with the separation layer included in the insulating layer  715  (a layer included in the insulating layer  715  which is in contact with the bonding layer  713  in the display panel) were not changed in the optical simulation. 
     Specifically, each of the layers in contact with the separation layer included in the insulating layer  705  and the insulating layer  715  was a 600-nm-thick silicon oxynitride film. 
     To secure the flexibility of the display panel, a structure in which stress does not concentrate on a particular film was used based on the calculation results. 
     By stacking a layer having a refractive index of approximately 1.5 (corresponding to a silicon oxynitride film) and a layer having a refractive index of approximately 1.9 (corresponding to a silicon nitride film) alternately so that antiphase interference occurs more often in the visible region, the region  110  transmitting visible light can have higher transmittance with respect to visible light. 
       FIG.  23    shows the measurement result of transmittance with respect to light of the region  110  transmitting visible light in the display panel which was actually manufactured. The transmittance with respect to light was measured with a spectrophotometer. 
     As shown in  FIG.  23   , the transmittance with respect to light of the region  110  transmitting visible light in the display panel which was manufactured has a high value, which is approximately 70% to 80% in the range of 450 nm to 650 nm, which is the peak range of an emission spectrum of the organic EL element. Note that the measurement result includes the reflectivity of approximately 8% in total including the reflectivity between the substrate  701  and air and that between the substrate  711  and air. The absorptance of the substrate  701  and that of the substrate  711  are each approximately 4% to 8%. Therefore, it can be concluded that the light transmittance of the inorganic insulating film which was optically optimized was able to be increased to approximately 95%. 
     As described above, the structure where the region transmitting visible light of the display panel overlaps the display region of another display panel with the light-transmitting layer provided therebetween was employed, and the inorganic insulating film included in the region transmitting visible light was optically optimized, whereby a large display device in which a seam between display panels was hardly recognized by a user was able to be manufactured. 
     Example 2 
     In this example, the results of manufacturing the display device of one embodiment of the present invention are described. A display device manufactured in this example is a kawara-type multidisplay. 
       FIG.  24 A  is a photograph of the display device displaying an image which was manufactured in this example. The display device illustrated in  FIG.  24 A  includes four display panels arranged in a matrix of two rows and two columns. The width of the region transmitting visible light of the display panel is approximately 2 mm. The display device was manufactured in such a manner that the region transmitting visible light was provided to overlap a display region of another display panel with a light-transmitting layer provided therebetween.  FIG.  4 A  is a schematic cross-sectional view illustrating two of the display panels included in the display device that are attached to each other. 
     In the display device illustrated in  FIG.  24 A , a light-emitting portion has a size of 27 inches diagonal (the size of the light-emitting portion of one display panel 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.  24 B  is a photograph of one display panel displaying an image. A structure that blocks visible light such as a lead wiring or a driver is not provided at all from an end portion of the light-emitting portion to an end portion of the display panel along two sides of the display panel, and the a region along two sides serve as a region transmitting visible light. As illustrated in an enlarged view of  FIG.  24 B , the width of the region transmitting visible light is approximately 2 mm. The region transmitting visible light has a very small thickness of less than 100 μm. Therefore, although the display device in this example has a region in which at most four display panels overlap with each other, a step formed on the display surface side is extremely small; thus, a seam hardly stands out. In addition, since the display panel has flexibility, part of an FPC can be placed under the light-emitting portion of the adjacent display panel by bending the vicinity of a region to which the FPC is connected. In this way, another display panel can be provided on four sides of the display panel, whereby a large-sized display panel is easily realized. 
     The display panel illustrated in  FIG.  24 B  is an active matrix organic EL display which has a light-emitting portion with a size of 13.5 inches diagonal, 1280×720×RGBY effective pixels, a resolution of 108 ppi, and an aperture ratio of 61.0%. 
     It is preferable that the display device in this example have smaller variation in luminance among a plurality of display panels. In the case where a lead wiring or the like is not provided along two sides as in the display panel in this example, the luminance of a region far from a wiring is low in some cases. Thus, the display panel in this example has six transistors and two capacitors in a pixel circuit to perform internal correction. Furthermore, the pixel arrangement where four subpixels (RGBY) including a yellow (Y) subpixel having a high current efficiency are arranged in a matrix of two rows and two columns was employed, whereby the amount of current flowing through the display panel is reduced and a voltage drop was suppressed. 
     In this example, as the light-emitting element, a tandem (stack) organic EL element emitting white light that includes a blue light-emitting unit  205  and a yellow light-emitting unit  209  was used (see  FIG.  25   ). An intermediate layer  207  was provided between two light-emitting units. The light-emitting element was provided over a stack  201 . The stack  201  includes a substrate and a transistor. The light-emitting element has a top emission structure. The light from the light-emitting element is extracted outside through color filters (a yellow color filter CFY, a blue color filter CFB, a green color filter CFG, and a red color filter CFR). A reflective electrode was used as an anode  203  of the light-emitting element, a transflective electrode was used as the cathode  211 , and a microcavity structure was used. Therefore, a change in chromaticity depending on the viewing angle in the pixel arrangement of RGBY can be smaller than that in the pixel arrangement of RGBW including a white (W) subpixel. 
       FIG.  26    illustrates the measurement results of luminance when a white color (luminance of 300 cd/m 2 ) is displayed on the entire surface of the display panel in this example.  FIG.  26    illustrates the measurement results of luminances at two places in the panel. One place is a region close to a lead wiring which corresponds to the upper left side of  FIG.  24 B , and the other place is a region close to a region transmitting visible light corresponding the lower right side of  FIG.  24 B . The results obtained by measuring four display panels show that there was no large variation between the luminances of the two places in each panel. Luminance does not decrease even in the region far from the lead wiring and close to the region transmitting visible light. The above results indicate that variation in luminance is less likely to be caused among the plurality of display panels in the display device in this example. 
     Note that the structure of the transistor used in this example is similar to that in Example 1, and the detailed description is omitted. 
     Furthermore, in this example, 36 display panels illustrated in  FIG.  24 B  were connected together, whereby an 81-inch display device illustrated in  FIG.  27    was manufactured. The display device having a high resolution of 8k4k with 7680×4320 effective pixels was manufactured. 
     As described in this example, in one embodiment of the present invention, a large-sized display device in which a seam between display panels is hardly recognized by a user was able to be obtained. 
     Example 3 
     In this example, the results of manufacturing the display device of one embodiment of the present invention are described. A display device manufactured in this example is a kawara-type multidisplay. 
     First, the display panel used in the display device in this example is described. 
       FIG.  28 A  is a schematic view of the display panel in this example. The display panel illustrated in  FIG.  28 A  is an active matrix organic EL display which has a light-emitting portion  250  with a size of 13.5 inches diagonal, 1280×720 effective pixels, a resolution of 108 ppi, and an aperture ratio of 61.0%. The display panel includes a demultiplexer (DeMUX)  253  serving as a source driver. In addition, the display panel also includes a scan driver  255 . Two sides of the light-emitting portion  250  are in contact with a region  251  transmitting visible light. A lead wiring  257  is provided along the other two sides. 
     A channel-etched transistor including a CAAC-OS is used as a transistor. Note that an In—Ga—Zn-based oxide is used for the oxide semiconductor. 
     As the light-emitting element, a tandem (stack) organic EL element emitting white light is used. The light-emitting element has a top emission structure, and the light from the light-emitting element is extracted outside through a color filter. 
       FIG.  28 B  is a schematic view of overlapping four display panels in a matrix of two rows and two columns.  FIG.  28 C  shows a cross-sectional schematic view taken along a dashed dotted line X-Y in  FIG.  28 B . 
     The display device in this example is formed by overlapping a plurality of display panels so that a non-display region between display regions is made small. Specifically, the light-transmitting layer  103  is provided between the region  251  transmitting visible light of an upper display panel and the light-emitting portion  250  of a lower display panel. 
     A structure that blocks visible light such as a lead wiring or a driver is not provided at all from an end portion of the light-emitting portion  250  to an end portion of the display panel along two sides of the display panel, and the a region along two sides serve as a region  251  transmitting visible light. The width of the region  251  transmitting visible light of the display panel is 2 mm. The thickness of the region  251  transmitting visible light (also referred to as a thickness of one display panel) is very small, which is less than 100 μm. Therefore, although the display device in this example has a region in which at most four display panels overlap with each other, a step formed on the display surface side is extremely small; thus, a seam hardly stands out. 
     The four display panels have flexibility. Thus, as illustrate in  FIG.  28 C , a region near the FPC  112   a  of the lower display panel can be bent so that part of the lower display panel and part of the FPC  112   a  can be placed under the light-emitting portion  250  of the upper display panel adjacent to the FPC  112   a . As a result, the FPC  112   a  can be placed without physical interference with the rear surface of the upper display panel. In this way, another display panel can be provided on four sides of the display panel, whereby a large-sized display panel is easily realized. 
     In this example, an absorption film including attachment layers on both surfaces of a base material was used as the light-transmitting layer  103 . With use of the attachment film, two display panels included in the display device can be detachably attached to each other. An attachment layer on one surface of the light-transmitting layer  103  can be attached to the substrate  152   a , and an attachment layer on the other surface of the light-transmitting layer  103  can be attached to the substrate  151   b.    
     In  FIG.  28 B , the light-transmitting layer  103  includes not only a portion overlapping with the region  251  transmitting visible light, but also a portion overlapping with the light-emitting portion  250 . In  FIG.  28 C , the light-transmitting layer  103  overlaps with the entire region  251  transmitting visible light from an end portion of the substrate  151   b , and also overlaps with part of the region  155   b  containing a display element. Note that the light-transmitting layer  103  is not provided on a curved region of the display panel that is close to a region to which an FPC is connected illustrated in  FIG.  28 C . However, the light-transmitting layer  103  may be provided on a curved region of the display panel depending on the thickness or flexibility of the light-transmitting layer  103 . 
     Each of the display panels was formed by attaching a substrate and an element layer with a bonding layer. For example, as illustrated in  FIG.  28 C , the substrate  151   a , the substrate  152   a , the substrate  151   b , and the substrate  152   b  are attached to the element layer  153   a , the element layer  153   a , the element layer  153   b , and the element layer  153   b  respectively, with the bonding layer  157 . Each of the element layers includes a region  155  containing a display element and a region  156  including a wiring electrically connected to the display element. 
     In addition, the manufactured display panel was subjected to a bending test.  FIGS.  29 A to  29 C  show how the bending test was performed. A bent portion is a portion shown by a dotted line in  FIG.  28 A , which is a region between the light-emitting portion  250  and the FPC connected portion and includes lead wirings used for a power source. Changing the display panel in shape from the state in  FIG.  29 A  to the state in  FIG.  29 B  and returning to the state in  FIG.  29 A  was counted as one bending, and the bending was repeated 100,000 times. The curvature radius for bending the display panel was 5 mm. In the bending test, one bending was performed in approximately 2 seconds.  FIG.  29 C  is a photograph of the display panel seen from a direction denoted by an arrow in  FIG.  29 B . 
       FIG.  29 D  is a photograph of an image displayed on the display panel before the test.  FIG.  29 E  is a photograph of an image displayed on the display panel after the test. A display defect was not observed in the display panel after the test. 
     Note that the luminance of the light-emitting portion  250  might be perceived different between in part which is viewed through the region  251  transmitting visible light and part which is viewed without through the region  251  transmitting visible light. Therefore, as illustrated in  FIG.  30 A , it is preferable that an image be displayed with a higher luminance in part overlapping with the region  251  transmitting visible light as compared with the other parts (for example, a data voltage of the part overlapping with the region  251  transmitting visible light is set higher than the other parts) because luminance of the entire light-emitting portion  250  can be uniform. 
     In this example, 36 display panels illustrated in  FIG.  28 A  were arranged in a matrix of six rows and six columns, whereby an 81-inch display device illustrated in  FIG.  31    was manufactured. 
     In this example, the display panels were driven by respective driver circuits. As illustrated in  FIG.  30 B , a signal output from an  8   k  recorder was divided into 36 parts and input to respective driver circuits. The timing of scanning in the first stage of each display panel was set to be at the same time. 
     In this example, a display device illustrated in  FIG.  31    having a high resolution of 8k4k with 7680×4320 effective pixels was manufactured. Note that the weight of one display panel including an FPC is approximately 26 g, and the weight of 36 display panels is less than or equal to 1 kg (here, the weight of the display panel and an FPC is mentioned, and the weight of a frame for fixing the display panel, and the like is not included). 
       FIG.  32    shows an observation result of a seam between the display panels. Note that an image displayed in  FIG.  31    is different from that in  FIG.  32   .  FIG.  32    shows a portion where the display panels overlap with each other (the width of 2 mm). As described above, with the use of one embodiment of the present invention, a seam between the display panels is hardly recognized or is negligible in a distance between the display panel and a user even if it can be observed in a near distance. 
     As described above, in one embodiment of the present invention, a large-sized display device in which a seam between display panels is hardly recognized by a user was able to be obtained. 
     EXPLANATION OF REFERENCE 
       10 : display device,  11 : display region,  15 : column,  16 : wall,  100 : display panel,  100   a : display panel,  100   b : display panel,  100   c : display panel,  100   d : display panel,  101 : display region,  101   a : display region,  101   b : display region,  101   c : display region,  101   d : display region,  102 : region,  102   a : region,  102   b : region,  103 : light-transmitting layer,  103   a : light-transmitting layer,  103   a   1 : light-transmitting layer,  103   a   2 : light-transmitting layer,  103   b : light-transmitting layer,  103   b   1 : light-transmitting layer,  103   b   2 : light-transmitting layer,  110 : region transmitting visible light,  110   a : region transmitting visible light,  110   b : region transmitting visible light,  110   c : region transmitting visible light,  110   d : region transmitting visible light,  112   a : FPC,  112   b : FPC,  120 : region blocking visible light,  120   a : region blocking visible light,  120   b : region blocking visible light,  120   c : region blocking visible light,  123 : FPC,  131 : resin layer,  132 : protective substrate,  133 : resin layer,  134 : protective substrate,  141 : pixel,  141   a : pixel,  141   b : pixel,  142   a : wiring,  142   b : wiring,  143   a : circuit,  143   b : circuit,  145 : wiring,  151 : substrate,  151   a : substrate,  151   b : substrate,  152 : substrate,  152   a : substrate,  152   b : substrate,  153   a : element layer,  153   b : element layer,  154 : bonding layer,  155 : region,  155   a : region,  155   b : region,  156 : region,  156   a : region,  156   b : region,  157 : bonding layer,  201 : stack,  203 : anode,  205 : blue light-emitting unit,  207 : intermediate layer,  209 : yellow light-emitting unit,  211 : cathode,  250 : light-emitting portion,  251 : region transmitting visible light,  253 : demultiplexer,  255 : scan driver,  257 : lead wiring,  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 : bonding 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 : touch panel,  505 B: touch panel,  509 : FPC,  590 : substrate,  591 : electrode,  592 : electrode,  593 : insulating layer,  594 : wiring,  595 : touch sensor,  597 : bonding layer,  598 : wiring,  599 : connection layer,  600 : input portion,  602 : sensor unit,  603   d : driver circuit,  603   g : driver circuit,  650 : capacitor,  651 : electrode,  652 : electrode,  653 : insulating layer,  667 : window portions,  670 : protective layer,  701 : substrate,  703 : bonding layer,  705 : insulating layer,  711 : substrate,  713 : bonding layer,  715 : insulating layer,  804 : light-emitting portion,  806 : driver circuit portion,  808 : FPC,  813 : gate insulating layer,  814 : conductive layer,  815 : insulating layer,  817 : insulating layer,  817   a : insulating layer,  817   b : insulating layer,  820 : transistor,  821 : insulating layer,  822 : bonding layer,  823 : spacer,  824 : transistor,  825 : connector,  830 : light-emitting element,  831 : lower electrode,  832 : optical adjustment layer,  833 : EL layer,  835 : upper electrode,  845 : coloring layer,  847 : light-blocking layer,  849 : overcoat,  856 : conductive layer,  857 : conductive layer,  857   a : conductive layer,  857   b : conductive layer,  7000 : display portion,  7001 : display portion,  7100 : mobile phone,  7101 : housing,  7103 : operation button,  7104 : external connection port,  7105 : speaker,  7106 : microphone,  7200 : television set,  7201 : housing,  7203 : stand,  7211 : remote controller,  7300 : portable information terminal,  7301 : housing,  7302 : operation button,  7303 : information,  7400 : lighting device,  7401 : stage,  7402 : light-emitting portion,  7403 : operation switch,  7500 : portable information terminal,  7501 : housing,  7502 : member,  7503 : operation button,  7600 : portable information terminal,  7601 : housing,  7602 : hinges,  7650 : portable information terminal,  7651 : non-display portion,  7700 : portable information terminal,  7701 : housing,  7703   a : button,  7703   b : button,  7704   a : speaker,  7704   b : speaker,  7705 : external connection port,  7706 : microphone,  7709 : battery,  7800 : portable information terminal,  7801 : band,  7802 : input-output terminal,  7803 : operation button,  7804 : icon, and  7805 : battery 
     This application is based on Japanese Patent Application serial no. 2014-156168 filed with Japan Patent Office on Jul. 31, 2014, Japanese Patent Application serial no. 2014-219131 filed with Japan Patent Office on Oct. 28, 2014, Japanese Patent Application serial no. 2014-243195 filed with Japan Patent Office on Dec. 1, 2014, and Japanese Patent Application serial no. 2015-109642 filed with Japan Patent Office on May 29, 2015, the entire contents of which are hereby incorporated by reference.