Display device comprising plural panels

To provide a display device that is suitable for increasing in size. To provide a display device in which display unevenness is suppressed. To provide a display device that can display an image along a curved surface. The display device includes two display panels, two plates, two stages, two driver circuits, two adjusting units, and a frame. Each display panel includes a display portion, an operating circuit portion, a terminal, an external electrode, a transparent portion, and a first portion and has flexibility. Each transparent portion includes a region transmitting visible light. The display panels are fixed so that transparent portions and parts of the display portions extend beyond the plates. The display portion of one of the two display panels overlaps with the transparent portion of the other display panel.

TECHNICAL FIELD

One embodiment of the present invention relates to a display device.

BACKGROUND ART

In recent years, larger display devices have been required. For example, a television device for home use (also referred to as a TV or a television receiver), digital signage, and a public information display (PID) are given. Larger digital signage, PID, and the like can provide the increased amount of information, and attract more attention when used for advertisement or the like, so that the effectiveness of the advertisement is expected to be increased.

Examples of the display device include, typically, a light-emitting device including a light-emitting element such as an organic electroluminescent (EL) element or a light-emitting diode (LED), a liquid crystal display device, and an electronic paper performing display by an electrophoretic method or the like.

For example, in a basic structure of an organic EL element, a layer containing a light-emitting organic compound is provided between a pair of electrodes. By voltage application to this element, the light-emitting organic compound can emit light. A display device including such an organic EL element needs no backlight which is necessary for liquid crystal display devices and the like; therefore, thin, lightweight, high contrast, and low power consumption display devices can be obtained. For example, Patent Document 1 discloses an example of a display device including an organic EL element.

Furthermore, Patent Document 2 discloses a flexible active matrix light-emitting device in which an organic EL element and a transistor serving as a switching element are provided over a film substrate.

REFERENCES

Patent Documents

DISCLOSURE OF INVENTION

An object of one embodiment of the present invention is to provide a display device that is suitable for increasing in size. Another object of one embodiment of the present invention is to provide a display device in which display unevenness is suppressed. Another object of one embodiment of the present invention is to provide a display device capable of uniform display in a display surface. Another object of one embodiment of the present invention is to provide a display device capable of display in which a joint portion in a display surface is hardly seen.

Another object is to provide a novel display device.

Note that the descriptions of these objects do not disturb the existence of other objects. In one embodiment of the present invention, there is no need to achieve all the objects. Objects other than the above objects will be apparent from and can be derived from the description of the specification and the like.

One embodiment of the present invention is a display device including two display panels, two plates, two stages, two driver circuits, two adjusting units, and a frame. The frame includes a plurality of pillars, a plurality of beams, and a plurality of bottom plates. The adjusting units have a function of adjusting positions and angles of the stages and are fixed to the frame. The driver circuits have a function of outputting signals for driving the display panels. The stages are fixed to the adjusting units and include regions provided with the driver circuits and the plates. The plates include first surfaces provided with mechanisms for connection to the stages and include convexly curved surfaces. Each display panel includes a display portion, an operating circuit portion, a terminal, an external electrode, a transparent portion, and a first portion and has flexibility. The display portion has a function of displaying an image. The operating circuit portion includes a circuit having a function of outputting a signal to the display portion and a wiring capable of electrically connecting the circuit to the terminal. The operating circuit is located in a region adjacent to the display portion. The terminal is electrically connected to the external electrode. The external electrode has a function of transmitting the signal output from the driver circuit to the operating circuit portion. The transparent portion includes a region transmitting visible light and is located in a region not overlapping with the operating circuit portion and adjacent to one side of the display portion. In each display panel, the first portion includes a region between the terminal and the display portion. Surfaces opposite to image display surfaces of the display panels are fixed to second surfaces opposite to the first surfaces of the plates so that the transparent portions and parts of the display portions extend beyond the plates. The first portions are provided along the convexly curved surfaces. The display portion of one of the two display panels overlaps with the transparent portion of the other display panel.

The display device further including a video signal divider and a video output unit is also one embodiment of the present invention. The video output unit has a function of outputting a video signal or an image signal to the video signal divider. The video signal divider has a function of dividing the video signal or the image signal into a plurality of signals and outputting the signals to the driver circuits.

The display device in which, in each display panel, the transparent portion is located in a region not overlapping with the operating circuit portion and adjacent to two sides of the display portion, and the first portion of one of the two display panels overlaps with the first portion of the other display panel is also one embodiment of the present invention.

In the display device, the driver circuits preferably have a function of adjusting color tone, luminance, or the like of images or video that is to be displayed on the display panels.

The display device in which the display portions each include a plurality of pixels, the pixels each include a light-emitting element and a transistor, and each light-emitting element includes a lower electrode, an upper electrode, and an EL layer between the lower electrode and the upper electrode is also one embodiment of the present invention.

The display device in which the display portions each include an auxiliary electrode and the auxiliary electrode is in contact with the upper electrode in a region between adjacent lower electrodes is also one embodiment of the present invention.

One embodiment of the present invention can provide a display device that is suitable for increasing in size. One embodiment of the present invention can provide a display device in which display unevenness is suppressed. One embodiment of the present invention can provide a display device capable of uniform display in a display surface. One embodiment of the present invention can provide a display device capable of display in which a joint portion in a display surface is hardly seen.

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 each drawing described in this specification, the size, the layer thickness, or the region of each component is exaggerated for clarity in some cases. Therefore, embodiments of the present invention are not limited to such a scale.

Note that in this specification and the like, ordinal numbers such as “first”, “second”, and the like are used in order to avoid confusion among components and do not limit the number.

Note that in this specification, the description “A has a shape such that an end portion extends beyond an end portion of B” may indicate, for example, the case where at least one of end portions of A is positioned on an outer side than at least one of end portions of B in a top view or a cross-sectional view.

In this embodiment, structure examples of a display device of one embodiment of the present invention are described with reference to drawings.

In each of two display panels included in the display device of one embodiment of the present invention, a transparent portion is provided adjacent to one side of a display portion. The display portion has a function of displaying an image, and the transparent portion transmits light emitted from the display portion. The two display panels are arranged to overlap with each other, and the transparent portion of one of the display panels and the display portion of the other display panel are arranged to overlap with each other. Thus, the display device can perform large-area display in which the joint portion of the display portions is hardly seen.

Each component of the display device will be described in detail below.

FIG. 1Ais a front view of a display device20A.FIG. 1Bis a cross-sectional view of the display device20A along the dashed-dotted line Y1-Y2inFIG. 1A.

The display device20A includes two display panels40, two plates50, two stages61, two driver circuits62, two adjusting units63, and a frame21A.

Note that one of two components in the display device20A is denoted by a reference numeral with the letter “a”, and the other is denoted by a reference numeral with the letter “b”. Note that in describing common parts of the two components, the two components are denoted by reference numerals without the letters “a” and “b” in some cases. The same can apply to two components included in a display device10and a display device20B which will be described later.

FIGS. 2A and 2Bshow the display device20A from which the plates50and the display panels40are removed.FIG. 2Ais a front view of the display device20A.FIG. 2Bis a cross-sectional view of the display device20A along the dashed-dotted line Y3-Y4inFIG. 2A. Components of the display device20A which are not shown inFIG. 1Aand their reference numerals are shown inFIG. 2A.

In the display device20A, the display panel40is attached to the plate50with a part of the display panel40bent (seeFIG. 1B).FIG. 1Cis a top view of the display panel40placed alone on a flat surface.

The frame21A includes a plurality of pillars and a plurality of beams. The frame21A can be provided with the two adjusting units63. In this embodiment, the adjusting units63are fixed to the beams of the frame21A (seeFIG. 2A).

The frame21A can be formed of a metal material which is processed easily and not deformed easily. Examples of the metal material include aluminum; copper; manganese; magnesium; an alloy of aluminum, copper, manganese, or magnesium (an aluminum alloy); iron; chromium; nickel; and an alloy of iron, chromium, or nickel (stainless steel).

The adjusting unit63has a function of adjusting the position and the angle of the stage61fixed onto the adjusting unit63. Specifically, the adjusting unit63allows the display panel40connected to the stage61to move in an X-axis direction and/or a Y-axis direction or to rotate around a Z-axis.

The adjusting unit63can adjust the positions of the two display panels40so that the display portions41aand41bof the display panels40become parallel and have no space therebetween.

As the adjusting unit63, a one-axis stage (also referred to as an X-axis stage) for adjusting the position in the X-axis direction, a one-axis stage (also referred to as a Y-axis stage) for adjusting the position in the Y-axis direction, and a tilt stage (also referred to as a goniometer stage) for adjusting the position in a direction of rotation around the Z-axis inFIG. 1Bcan be used in combination. Alternatively, a two-axis stage for adjusting the position in the X-axis direction and the Y-axis direction and the tilt stage may be used in combination. In this embodiment, the adjusting unit63includes the X-axis stage, the Y-axis stage, and the goniometer stage in the order from the side fixed to the frame21A (seeFIGS. 2A and 2B).

The driver circuit62has a function of converting an image signal or a video signal input to the driver circuit62to a signal for driving the display panel40and of outputting the converted signal to the display panel40. Furthermore, the driver circuit62has a function of supplying a power supply voltage required for light emission of the display panel40.

The driver circuit62preferably has a function of adjusting color tone, luminance, or the like in display of the display panel40, in which case variation can be corrected when the variation in display performance between the display panel40aand the display panel40boccurs.

The driver circuit62may have a function of generating an image signal or a video signal. A cable64may be connected to the driver circuit62. For example, a signal can be input to the driver circuit62from an external video output device through the cable64(seeFIG. 2B).

FIG. 3Ais a side view illustrating the display device10of one embodiment of the present invention. The display device10includes the display device20A, a video signal divider22, and a video output unit23. In the display device10, for example, a frame21includes the frame21A and a plurality of bottom plates over which the video signal divider22and the video output unit23are provided. The frame21can be formed of a metal material similar to that of the frame21A.

In the display device10, the driver circuit62aand the driver circuit62bare electrically connected to the video signal divider22through the cable64aand the cable64b, respectively. The video signal divider22is electrically connected to the video output unit23through a cable65. Note that the display panel40, the plate50, and the stage61are collectively referred to as a component group60(60aor60b) inFIG. 3A.

The video output unit23has a function of outputting, to the video signal divider22, a signal for an image or video that is to be displayed on the display panels40aand40b. As the video output unit23, a recording/reproducing device such as a Blu-ray Disc recorder or a digital versatile disc (DVD) recorder can be used.

In the case where a plurality of display panels is arranged in a tile pattern to form the display device, an uncompressed disk recorder (UDR) capable of outputting an image with high resolution, e.g., 4K (3840×2160 pixels) or 8K (7680×4320 pixels), without compression can be favorably used as the video output unit23. The number of display panels arranged in a tile pattern is, for example, nine (3×3) or thirty-six (6×6).

The video signal divider22has a function of dividing an input signal for an image or video and outputting the divided signals to a plurality of driver circuits or display devices.

For example, in the case where an image signal for certain display resolution is divided into nine and the divided signals are output to nine display devices by the video signal divider22, an image displayed using an image signal output to and received by each display device provides a pixel aspect equal to an original image and 1/9 display resolution. Then, display regions of the nine display devices are arranged to correspond to the order in which the original image signal is divided. Thus, an image can be displayed with the display resolution of the original image. Note that here, the term “pixel aspect” refers to the ratio between the display resolution of an image in the longitudinal direction and the display resolution of the image in the horizontal direction. The term “display resolution” refers to the total number of pixels forming a display portion of a display device or the total number of pixels forming an image.

In this embodiment, the image signal or the video signal input to the video signal divider22is divided into two and the divided signals are output to the two driver circuits62.

Referring again to the display device20A, the stage61has a region where the driver circuit62can be provided and a region where the plate50can be provided (seeFIG. 1B). Since the stage61has the region where the driver circuit62can be provided, the replacement of a component due to the specification change of the driver circuit62or maintenance can be performed easily, for example.

Note that the driver circuit62may be reduced in volume so as to be attached to the surface of the stage61opposite to the region where the plate50can be provided. This can reduce the region of the stage61where the driver circuit62is provided and accordingly can reduce the depth of the display device20A (the length in the Z-axis direction inFIG. 1B).

The stage61can be formed of a metal material similar to that of the frame21A.

The plate50includes a first surface provided with a mechanism for connection to the stage61and a side surface provided with a convexly curved surface (seeFIG. 1B). The plate50includes a region where the display panel40is provided on a surface (hereinafter referred to as a second surface) opposite to the first surface. In this embodiment, the mechanism includes a depression51to which a part of the stage61can be fit and a fastening52capable of sliding in the Y-axis direction. However, the mechanism is not limited thereto. Note that not the plate50, but the stage61may include a mechanism for setting the plate50to the stage61.

The plate50needs to be connected precisely to the stage61to accurately adjust the relative positions of the display portion41aand the display portion41busing the adjusting unit63. The alignment of the plate50and the stage61in the Y-axis direction can be achieved using the depression51and the fastening52. The alignment of the plate50and the stage61in the X-axis direction can be achieved using guides53to be described later.

The plate50can be formed of a metal material similar to that of the frame21A.

The display panel40is provided with the display portion41, a transparent portion42, an operating circuit portion43, a terminal45, and an external electrode46(seeFIG. 1C). The display panel40has flexibility.

The terminal45is electrically connected to a wiring in the operating circuit portion43and the external electrode46. The external electrode46is electrically connected to the driver circuit62, and a signal is output from the driver circuit62to the display panel40through the external electrode46(seeFIG. 1B). In this embodiment, a flexible printed circuit (FPC) is used as an example of the external electrode46.

The display portion41has a function of displaying an image. The display portion41may include a light-emitting element such as an organic EL element.

The operating circuit portion43has a function of outputting a signal to the display portion41. The operating circuit portion43includes a scan line driver circuit, a signal line driver circuit, and the like. Wirings for connecting the external electrode46to the scan line driver circuit and the signal line driver circuit are also included in the operating circuit portion43.

In the display panel40, the operating circuit portion43is provided in a position adjacent to the display portion41. In the structure shown inFIG. 1C, the operating circuit portion43is adjacent to two sides of the display portion41. The operating circuit portion43may be adjacent to one side of the display portion41. The operating circuit portion43may be a region which does not transmit visible light or a region which transmits visible light, depending on the structure of the scan line driver circuit or the like.

The transparent portion42includes a region which transmits visible light. A region where the transparent portion42is located is adjacent to the display portion41and does not overlap with the operating circuit portion43.

In the example shown inFIG. 1C, the transparent portion42is adjacent to a bottom side of the display portion41(a side opposite to the side near the terminal45); however, the position of the transparent portion42is not limited thereto. For example, the transparent portion42may be adjacent to a right side of the display portion41(a side opposite to a longer side of the display portion41which is adjacent to the operating circuit portion43).

The transparent portion42may be adjacent to two sides of the display portion41(e.g., the bottom side and the right side). The transparent portion42adjacent to two sides of the display portion41is preferable because the display panels40can be seamlessly arranged in a tile pattern. Furthermore, when there is no space between the display portion41and the transparent portion42, large-area display can be performed in which a joint portion of the display panels40arranged in a tile pattern is hardly seen.

It is preferable that the transparent portion42have high transmittance, because the boundary between a region behind the transparent portion42and the other region is hardly seen in performing display on the display portion41. Furthermore, it is preferable that the refractive index of a material of the transparent portion42be close to 1 because the reflection of external light can be suppressed.

The width of the transparent portion42(the length of the transparent portion42in the Y-axis direction inFIG. 1B) is equal to the distance between an end portion of the display panel40and a side of the display portion41which is adjacent to the transparent portion42(seeFIG. 1C). The transparent portion42may include a sealing layer having a function of suppressing the entry of an impurity such as water into the light-emitting element of the display portion41. That is, the width of the transparent portion42can be set depending on the sealing performance of the sealing layer and/or reliability required for the light-emitting element.

A specific structure of the display panel will be described in detail in Embodiment 2.

FIG. 1Bshows a structure in which the two display panels40are arranged in the Y-axis direction so that the display portion41aand the display portion41bare arranged seamlessly.

Note that in the two display panels shown inFIGS. 1A and 1B, the display panel located on the rear side (the display panel whose front surface is overlapped by the transparent portion42of the other display panel) is denoted by40a, and the display panel located on the front side is denoted by40b. Note that the positional relation and the connection relation between the display panel40aand the plate50aare equal to the positional relation and the connection relation between the display panel40band the plate50b.

InFIG. 1B, the display panel40has a surface where display on the display portion41can be seen and a surface opposite thereto (hereinafter the latter surface is referred to as a display rear surface), and the display rear surface is in contact with the second surface and the convexly curved surface of the plate50.

The display rear surface and the second surface may adhere to each other or be fixed to each other to be attachable to and detachable from each other. In the case where the display rear surface and the second surface are attachable to and detachable from each other, the display panel40can be replaced easily.

For example, a film having an adsorbing property (hereinafter referred to as an adsorptive film) can be used to make the display rear surface and the second surface attachable to and detachable from each other. Air between an object and the adsorptive film is removed to produce a low-pressure or vacuum state therebetween, so that the adsorptive film can be attached to the object. Alternatively, an adhesive film may be used to make the display rear surface and the second surface attachable to and detachable from each other.

In the case of using the adsorptive film or the adhesive film to fix the display rear surface and the second surface to each other, the film is attached to the second surface first. The film may be attached to either the whole area of the second surface or a part thereof. In the latter case, the film is preferably attached to at least a region of the second surface in the vicinity of the convexly curved surface. This can prevent the display panel40in the vicinity of an upper portion of the display portion41from being apart from the second surface in the case where a first portion44of the display panel40is bent along the convexly curved surface.

In the display panel40, a region between the terminal45and the display portion41is the first portion44(seeFIG. 1C). The first portion44is preferably provided along the convexly curved surface of the plate50as shown inFIG. 1B.

Furthermore, it is preferable that the first portion44and the convexly curved surface not be fixed to each other. Such a structure can enlarge the movable area of the external electrode46and increase the degree of flexibility in connection between the external electrode46and the driver circuit62. In addition, two display panels80can be arranged easily in the X-axis direction as described later.

Note that the first portion44of the display panel40is not necessarily provided along the whole area of the convexly curved surface of the plate50and may be provided along a part of the convexly curved surface as shown inFIG. 3B. Such a structure can increase the curvature radius of the first portion44and reduce physical stress applied to the display panel40accordingly.

As shown inFIG. 1B, the display panel40bis fixed to the plate50bso that the transparent portion42band a part of the display portion41bextend beyond the plate50b. The part of the display portion41bextending beyond the plate50ballows the display portion41bto be placed on the display panel40awithout contact between the plate50band the first portion44a.

For example, the length in the Y-axis direction of the part of the display portion41bextended beyond the plate50bcan be determined by making the top side of the display portion41aalign with the bottom side of the display portion41bin the Z-axis direction.

It is preferable that, in a portion where the transparent portion42band the display portion41aare in contact with each other, air and the like not be present between the transparent portion42band the display portion41a. Furthermore, it is preferable that the transparent portion42band the display portion41abe attachable to and detachable from each other.

The above-described adsorptive film can be used to make the transparent portion42band the display portion41aattachable to and detachable from each other. In the case of using the adsorptive film, it is preferable that the difference between the refractive index of the material of the transparent portion42band the refractive index of a material of the adsorptive film be small. This can suppress the reflection of external light at the interface between the transparent portion42band the adsorptive film and increase visibility of display on the display portion41ain a region overlapping with the transparent portion42b.

Since the display panels40have flexibility, the plates50aand50bcan be arranged so that the second surfaces thereof form one plane and a part of the display panel40bextending beyond the plate50bcan be bent and placed on the surface of the display panel40a.

By arranging the plates50aand50bso that the second surfaces thereof form one plane, a display surface of the display portion11A can be made approximately flat without steps.

The process for setting the display panels40aand40bto form the display device20A is described below with reference toFIGS. 1A and 1BandFIGS. 2A and 2B.

Note that the adjusting units63aand63band the stages61aand61bare provided for the frame21A in advance. First, the driver circuits62aand62bare set onto the stages61aand61b, respectively (seeFIGS. 2A and 2B).

Then, the plate50ais made to adhere to the display panel40aor fixed to the display panel40aso as to be attachable thereto and detachable therefrom. Specifically, the display rear surface of the display panel40aand the second surface of the plate50aare disposed in close contact with each other with the adsorptive film or the film having an adhesion property. At this time, it is preferable that the first portion44aand the convexly curved surface of the plate50anot be fixed to each other.

The plate50ais provided for the stage61a. Specifically, a part of the stage61ais fit into the depression51a, and the first surface of the plate50ais made to overlap with a side surface of the stage61aso as to be in contact with each other. After that, the fastening52ais slid up to fix the plate50ato the stage61a. Then, the external electrode46aand the driver circuit62aare connected to each other.

Next, the display panel40bis fixed to the plate50bin a manner similar to the above-described manner in which the display panel40ais fixed to the plate50a.

The plate50bis provided for the stage61b. The plate50bcan be provided for the stage61bin a manner similar to the above-described manner in which the plate50ais provided for the stage61a. Note that the plate50bis provided such that the part of the display panel40bextended beyond the plate50bis located on the front surface of the display panel40a. Then, the external electrode46band the driver circuit62bare connected to each other.

Note that when the plate50bis provided for the stage61b, the stage61amay be moved in the Y-axis direction using the adjusting unit63aso that the plate50bdoes not contact the first portion44ain contact with the convexly curved surface of the plate50a. Alternatively, the stage61bmay be moved in the Y-axis direction using the adjusting unit63b.

Then, the position or the angle of the display portion41ais adjusted using the adjusting unit63aand/or the position or the angle of the display portion41bis adjusted using the adjusting unit63bso that the joint portion of the display portions41aand41bis hardly seen when the display portion11A is seen in the Z-axis direction.

In one method for relative alignment of the display portions41aand41b, for example, an image is displayed on the display portion11A as one display area, and then, a discontinuous portion of the image at or in the vicinity of the boundary between the display portions41aand41bis made as small as possible using the adjusting unit63aand/or the adjusting unit63b. As the image to be displayed on the display portion11A at this time, for example, an image having a stripe-like scale crossing the discontinuous portion is used, in which case the relative alignment of the display portions41aand41bcan be easily performed.

Finally, the transparent portion42band the display portion41aare fixed to each other so as to be attachable to and detachable from each other while air is prevented from being present therebetween (seeFIGS. 1A and 1B). For example, the adsorptive film can be used to fix them so as to be attachable to and detachable from each other.

Through the above-described process, the display panels40aand40bcan be set in the display device10.

Modification Example 1

In this embodiment described so far, the structure of the display device20A in which the two display panels are adjacent to each other in the Y-axis direction is described. In Modification Example 1, a structure of a display device20B in which two display panels are adjacent to each other in the X-axis direction will be described.

Note that only differences between the display device20B and the display device20A shown inFIGS. 1A and 1Bwill be described below.

FIG. 4Ais a front view of the display device20B in which two display panels80aand80bare arranged in the X-axis direction.FIG. 4Bis a cross-sectional view of the display device20B along the dashed-dotted line Y5-Y6inFIG. 4A. Note that in the two display panels shown inFIGS. 4A and 4B, the display panel located on the rear side is denoted by80a, and the display panel located on the front side is denoted by80b.

In the display device20B, the display panel80is attached to the plate90with a part of the display panel80bent (seeFIG. 4B).FIG. 4Cis a top view of the display panel80placed alone on a flat surface.

FIGS. 5A and 5Bshow the display device20B from which the plates90and the display panels80are removed.FIG. 5Ais a front view of the display device20B.FIG. 5Bis a cross-sectional view of the display device20B along the dashed-dotted line Y7-Y8inFIG. 5A. Components of the display device20B which are not shown inFIG. 4Aand their reference numerals are shown inFIG. 5A.

In the display device20B, the display portion41aof the display panel80aand the display portion41bof the display panel80bare arranged seamlessly. Thus, a display portion11B can be used as one display region displaying an image or video. The display portion11B is a region surrounded by a thick dashed line inFIG. 4A.

A frame21B differs from the frame21A shown inFIG. 2Ain that the frame21B includes a plurality of pillars and a plurality of beams with which the two display panels80are arranged in the X-axis direction (seeFIG. 5A).

FIG. 4Dis a rear view of a stage91and a plate90in a state where the plate90is provided for the stage91. In the stage91, the width (the length in the X-axis direction) of a lower portion of a region where the plate90is provided is smaller than the width of an upper portion of the region where the plate90is provided, which is different from that in the stage61. A first surface of the plate90is provided with the guides53. The distance between the two guides53is equal to the width of the lower portion of the stage91and is indicated by W1. With such a structure, the positions of the plate90and the stage91in the X-axis direction can be aligned with high precision at the time of attaching the plate90to the stage91.

The frame21B and the stage91can be formed of a metal material similar to that of the frame21A. The frame21B and the stage91may be formed of different materials.

The display panel80is provided with a transparent portion82in a position adjacent to the right side and the lower side of the display portion41(seeFIG. 4C). As shown inFIG. 4A, the display portion41aand the transparent portion82boverlap with each other in the display device20B. Furthermore, the first portion44aof the display panel80aand the first portion44bof the display panel80boverlap with each other. Such a structure allows a plurality of display panels80to be arranged in the X-axis direction and the Y-axis direction without the joint portion of the display portions41, achieving large-area display. Note thatFIGS. 1A and 1Band the description relating toFIGS. 1A and 1Bin this specification can be referred to for a method of arranging the display panels80in the Y-axis direction.

The display panel80bis fixed to the plate90bso that the transparent portion82band a part of the display portion41bextend beyond the plate90bin the X-axis direction and the Y-axis direction (seeFIG. 4A).

For example, the length in the X-axis direction of the part of the display portion41bextended beyond the plate90bcan be determined by making the right side of the display portion41balign with the left side of the display portion41ain the Z-axis direction.

The process for setting the display panels80aand80bto form the display device20B is described below with reference toFIGS. 4A to 4DandFIGS. 5A and 5B.

Note that the adjusting units63aand63band stages91aand91bare provided for the frame21B in advance. First, the driver circuits62aand62bare set onto the stages91aand91b, respectively (seeFIGS. 5A and 5B).

Then, the plate90ais made to adhere to the display panel80aor fixed to the display panel80aso as to be attachable thereto and detachable therefrom. Specifically, the display rear surface of the display panel80aand the second surface of the plate90aare disposed in close contact with each other with the adsorptive film or the film having an adhesion property. At this time, it is preferable that the first portion44aand the convexly curved surface of the plate90anot be fixed to each other.

The plate90ais provided for the stage91a. Specifically, a part of the stage91ais fit into the depression51a, and the plate90ais moved in the X-axis direction so that a lower portion of the stage91ais positioned between the two guides53a. Then, the first surface of the plate90ais made to overlap with a side surface of the stage91aso that they are in contact with each other. After that, the fastening52ais pulled up to fix the plate90ato the stage91a. Then, the external electrode46aand the driver circuit62aare connected to each other.

Next, the display panel80bis fixed to the plate90bin a manner similar to the above-described manner in which the display panel80ais fixed to the plate90a. Note that a convexly curved surface of the plate90band the first portion44bare not fixed to each other.

The plate90bis provided for the stage91b. The plate90bcan be provided for the stage91bin a manner similar to the above-described manner in which the plate90ais provided for the stage91a. Note that the plate90bis provided such that the part of the display panel80bextended beyond the plate90bis located on the front surface of the display panel80a.

Note that when the plate90bis attached to the stage91b, the stage91amay be moved in the X-axis direction using the adjusting unit63aso that the plate90bdoes not contact the display panel80a. Alternatively, the stage91bmay be moved in the X-axis direction using the adjusting unit63b.

Then, the position or the angle of the display portion41ais adjusted using the adjusting unit63aor the position or the angle of the display portion41bis adjusted using the adjusting unit63bso that the joint portion of the display portions41aand41bis hardly seen when the display portion11B is seen in the Z-axis direction.

Finally, the transparent portion82band the display portion41aare fixed to each other so as to be attachable to and detachable from each other while air is prevented from being present therebetween (seeFIGS. 4A and 4B). For example, the adsorptive film can be used to fix them so as to be attachable to and detachable from each other.

Finally, the first portion44bis placed along the convexly curved surface of the plate90aand the first portion44a, and the external electrode46bis connected to the driver circuit62b.

Note that a curvature radius of a bent portion of the first portion44bis longer than a curvature radius of a bent portion of the first portion44abecause the first portion44boverlaps the first portion44a. Therefore, the external electrode46brequired for connection between the display panel80band the driver circuit62bis longer than the external electrode46arequired for connected between the display panel80aand the driver circuit62a(seeFIG. 4A). This means that excess tension is generated in the external electrode46band the terminal45bwhen the display panel80band the driver circuit62bare connected to each other. Thus, the length of the external electrode46bor the first portion44bin the longitudinal direction of the display panel80bis preferably adjusted. A connection position of the driver circuit62band the external electrode46bmay be adjusted.

Structure Example of Display Portion

Next, a structure example of a display portion of a display panel included in a display device of one embodiment of the present invention will be described.FIG. 6Ais a top view of a display panel30in which a transparent portion32is adjacent to two sides of the display portion41.FIG. 6Bis a top view in which a region P inFIG. 6Ais enlarged, andFIG. 6Cis a top view in which a region Q inFIG. 6Ais enlarged.

As illustrated inFIG. 6C, in the display portion41, a plurality of pixels31is arranged in a matrix. In the case where the display panel30which is capable of full color display with three colors of red, blue, and green is formed, the pixel31can display any of the three colors. Alternatively, a pixel which can display white or yellow in addition to the three colors may be provided. A region including the pixels31corresponds to the display portion41.

One pixel31is electrically connected to a wiring34cand a wiring34d. The plurality of wirings34ceach intersects with the wiring34d, and is electrically connected to an operating circuit33c. The plurality of wirings34dis electrically connected to an operating circuit33d. One of the operating circuits33cand33dcan function as a scan line driver circuit, and the other can function as a signal line driver circuit. A structure without one of the operating circuits33cand33dor both of them may be employed.

InFIG. 6B, a plurality of wirings35electrically connected to the operating circuit33cor the operating circuit33dis provided. The wiring35is electrically connected to the external electrode46in a region not shown in the figure and has a function of supplying a signal from the outside to the operating circuits33cand33d.

InFIG. 6B, a region including the operating circuit33c, the operating circuit33d, and the plurality of wirings35corresponds to the operating circuit portion43inFIG. 6A.

InFIG. 6C, a region outside the pixel31provided closest to the end corresponds to the transparent portion32. The transparent portion32does not include the members blocking visible light, such as the pixel31, the wiring34c, and the wiring34d. Note that in the case where part of the pixel31, the wiring34c, or the wiring34dtransmits visible light, the part of the pixel31, the wiring34c, or the wiring34dmay be provided to extend to the transparent portion32.

Here, the width W2of the transparent portion32indicates the narrowest width of the transparent portion32provided in the display panel30in some cases. In the case where the width W2of the display panel30varies depending on the positions, the width of the shortest portion can be referred to as the width W2. InFIG. 6C, the distance between the pixel31and the end surface of the substrate (that is, the width W2of the transparent portion32) in the vertical direction is the same as that in the horizontal direction.

FIG. 6Dis a cross-sectional view taken along the dashed-dotted line X1-X2inFIG. 6C. The display panel30illustrated inFIG. 6Dincludes a pair of substrates (a substrate36and a substrate37) each of which transmits visible light. The substrate36and the substrate37are bonded to each other with an adhesive layer38. The pixel31, the wiring34d, and the like are provided for the substrate36.

As illustrated inFIGS. 6C and 6D, in the case where the pixel31is positioned closest to the end of the display portion41, the width W2of the transparent portion42is the distance between the end portion of the substrate36or the substrate37and the end portion of the pixel31.

Note that the end portion of the pixel31refers to the end portion of the member that is positioned closest to the end and blocks visible light in the pixel31. 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 pixel31, the end portion of the pixel31may 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. 7Ashows the case where the position of the wiring34cis different from that inFIG. 6C.FIG. 7Bis a cross-sectional view taken along dashed-dotted line Y9-Y10inFIG. 7A, andFIG. 7Cis a cross-sectional view taken along dashed-dotted line X3-X4inFIG. 7A.

As illustrated inFIGS. 7A to 7C, in the case where the wiring34cis positioned closest to the end of the display portion41, the width W2of the transparent portion32is the distance between the end portion of the substrate36or the substrate37and the end portion of the wiring34c. In the case where the wiring34ctransmits visible light, the transparent portion32may include a region where the wiring34cis provided.

Here, in the case where the density of pixels provided in the display portion41of the display panel30is high, misalignment may occur when the two display panels30are bonded.

FIG. 8Ashows a positional relationship between the display portion41aof the display panel30aprovided on the rear side and the display portion41bof the display panel30bprovided on the front side, seen from the display surface side.FIG. 8Ashows the vicinities of the corner portions of the display portions41aand41b. Part of the display portion41ais covered with the transparent portion32b.

FIG. 8Ashows an example in which adjacent pixels31aand31bare relatively deviated in one direction (X-axis direction). The arrow in the drawing denotes a direction in which the display panel30ais deviated from the display panel30b.FIG. 8Bshows an example in which the adjacent pixels31aand31bare relatively deviated in a vertical direction and a horizontal direction (X-axis direction and Y-axis direction).

In the examples ofFIGS. 8A and 8B, the distances deviated in the vertical direction and the horizontal direction are each shorter than the length of one pixel. In this case, image data of the image displayed on either one of the display portions41aand41bis corrected depending on the deviation distance, whereby the display quality can be maintained. Specifically, when the deviation makes the distance between the pixels smaller, the data is corrected so that the gray level (luminance) of the pixels is low, and when the deviation makes the distance between the pixels larger, the data is corrected so that the gray level (luminance) of the pixels is high. Alternatively, when the pixels are deviated by a distance of more than one pixel, the data is corrected so that the pixel positioned on a rear side is not driven and the image data is shifted by one column.

FIG. 8Cshows an example in which the pixels31aand31b, which should be adjacent, are relatively deviated in one direction (X-axis direction) by a distance of more than one pixel. When the deviation of more than one pixel occurs, the pixels are driven so that projecting pixels (pixels which are hatched) are not displayed. Note that the same applies to the case where the deviation direction is the Y-axis direction.

When the plurality of display panels30are made to overlap with each other, in order to suppress misalignment, each of the display panels30is preferably provided with an alignment marker or the like. Alternatively, a projection and a depression may be formed on the surfaces of the display panels30, and the projection and the depression may be attached to each other in a region where the two display panels30overlap.

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 portion41of the display panel30. For example, it is preferable that one or more, preferably three or more, further preferably five or more extra pixel columns along either one or both of a scan line and a signal line be provided in addition to the pixel columns used for display.

This embodiment can be combined with any other embodiment as appropriate.

In this embodiment, structure examples of a display panel which can be used in a display device of one embodiment of the present invention are described with reference to drawings.

Although a display panel mainly including an organic EL element is described in this embodiment as an example, a display panel which can be used in a display device of one embodiment of the present invention is not limited to this example. A light-emitting panel or a display panel including another light-emitting element or display element which will be described later in this embodiment as an example can also be used in a display device of one embodiment of the present invention.

Structure Example 1

FIG. 9Ais a plan view of the display panel, andFIG. 9Cis an example of a cross-sectional view taken along the dashed-dotted line A1-A2inFIG. 9A.FIG. 9Calso shows an example of a cross-sectional view of a transparent portion810.

The display panel in Structure Example 1 is a top-emission display panel using a color filter method. In this embodiment, the display panel can have a structure in which subpixels of three colors of red (R), green (G), and blue (B), for example, express one color; a structure in which subpixels of four colors of R, G, B, and white (W) express one color; a structure in which subpixels of four colors of R, G, B, and yellow (Y) express one color; or the like. There is no particular limitation on color elements, and colors other than R, G, B, W, and Y may be used. For example, cyan, magenta, or the like may be used.

The display panel shown inFIG. 9Aincludes the transparent portion810, a display portion804, an operating circuit portion806, and an FPC808. The transparent portion810is adjacent to the display portion804and provided along two sides of the display portion804. The operating circuit portion806includes a scan line driver circuit, a signal line driver circuit, and the like.

The display panel illustrated inFIG. 9Cincludes a substrate701, an adhesive layer703, an insulating layer705, a plurality of transistors, a conductive layer857, an insulating layer815, an insulating layer816, an insulating layer817, a plurality of light-emitting elements, an insulating layer821, an adhesive layer822, a coloring layer845, a light-blocking layer847, an insulating layer715, an adhesive layer713, and a substrate711. The adhesive layer822, the insulating layer715, the adhesive layer713, and the substrate711transmit visible light. Light-emitting elements and transistors included in the display portion804and the operating circuit portion806are sealed with the insulating layer705, the insulating layer715, and the adhesive layer822.

The display portion804includes a transistor820and a light-emitting element830over the substrate701with the adhesive layer703and the insulating layer705provided therebetween. The light-emitting element830includes a lower electrode831over the insulating layer817, an EL layer833over the lower electrode831, and an upper electrode835over the EL layer833. That is, the light-emitting element830includes the lower electrode831, the upper electrode835, and the EL layer833provided between the lower electrode831and the upper electrode835.

The lower electrode831is electrically connected to a source electrode or a drain electrode of the transistor820. An end portion of the lower electrode831is covered with the insulating layer821. The lower electrode831preferably reflects visible light. The upper electrode835transmits visible light.

In addition, the display portion804includes the coloring layer845overlapping with the light-emitting element830and the light-blocking layer847overlapping with the insulating layer821. The space between the light-emitting element830and the coloring layer845is filled with the adhesive layer822.

The insulating layer815and the insulating layer816have an effect of inhibiting diffusion of impurities to a semiconductor included in the transistors. As the insulating layer817, an insulating layer having a planarization function is preferably selected in order to reduce surface unevenness due to the transistor.

Note that the insulating layer815and/or the insulating layer816may be omitted in a region where a transistor is not provided in the display panel. In particular, it is preferable that the insulating layer815and/or the insulating layer816not be formed in the transparent portion810because the transmittance is improved.FIGS. 9A to 9Cshow structures in each of which the insulating layer815is not formed in the transparent portion810. For example, silicon nitride and silicon oxynitride can be used as the insulating layer815and the insulating layer816, respectively.

The operating circuit portion806includes a plurality of transistors over the substrate701with the adhesive layer703and the insulating layer705provided therebetween. InFIG. 9C, one of transistors included in the operating circuit portion806is illustrated.

The insulating layer705and the insulating layer715are preferably highly resistant to moisture, in which case entry of impurities such as water into the light-emitting element830or the transistor820can be inhibited, leading to higher reliability of the display panel. When the display panel includes a substrate, the surface of the display panel can be protected from a physical impact, which is preferable. The substrate701is bonded to the insulating layer705with the adhesive layer703. The substrate711is bonded to the insulating layer715with the adhesive layer713.

The conductive layer857is electrically connected to an external electrode through which a signal (e.g., a video signal, a clock signal, a start signal, or a reset signal) or a potential from the outside is transmitted to the operating circuit portion806. Here, an example in which the FPC808is provided as the external electrode is described. To prevent an increase in the number of manufacturing steps, the conductive layer857is preferably formed using the same material and the same step(s) as those of the electrode or the wiring in the display portion or the driver circuit portion. Here, an example is described in which the conductive layer857is formed using the same material and the same step(s) as those of the electrodes of the transistor820.

In the display panel inFIG. 9C, the FPC808is positioned over the insulating layer715. The connector825is connected to the conductive layer857through an opening provided in the insulating layer715, the adhesive layer822, the insulating layer817, the insulating layer816, and the insulating layer815. The connector825is also connected to the FPC808. The FPC808and the conductive layer857are electrically connected to each other via the connector825.

FIG. 10shows an example of a cross-sectional view of a state where two display panels each shown inFIG. 9Care attached to each other with an adhesive layer723therebetween. Note that the two display panels may be fixed to each other so as to be attachable to and detachable from each other using an adsorptive layer instead of the adhesive layer723.

FIG. 10shows the display portion41a(corresponding to the display portion804shown inFIG. 9A) and the operating circuit portion43a(corresponding to the operating circuit portion806and the like shown inFIG. 9A) of the lower (rear) display panel and the display portion41b(corresponding to the display portion804shown inFIG. 9A) and the transparent portion42b(corresponding to the transparent portion810shown inFIG. 9A) of the upper (front) display panel. Furthermore, the cross-sectional view shown inFIG. 10shows an example of an overlapping portion (seeFIG. 1B) where the two display panels40aand40bdescribed in Embodiment 1 overlap with each other.

InFIG. 10, the display panel positioned on the upper side (the display surface side) includes the transparent portion810adjacent to the display portion804. Furthermore, the display portion804of the lower display panel and the transparent, portion810of the upper display panel overlap each other. Thus, a non-display region between the display regions of the two overlapping display panels can be reduced and even removed. As a result, a large-sized display device in which a joint portion of the display portions is hardly seen by the user can be obtained.

InFIG. 10, the adhesive layer723transmitting visible light is provided between the display portion804of the lower display panel and the transparent portion810of the upper display panel. The difference in refractive index between the adhesive layer723and the substrate701of the upper display panel and/or the substrate711of the lower display panel is preferably small. Such a structure can reduce reflection by the interface due to the difference in refractive index in a stack located over the display portion804of the lower display panel. In addition, display unevenness or luminance unevenness of a large display device can be suppressed.

Structure Example 2

FIG. 9Ais a plan view of the display panel, andFIG. 11Ais an example of a cross-sectional view taken along the dashed-dotted line A1-A2inFIG. 9A. The display panel in Structure Example 2 is a top-emission display panel using a color filter method, which differs from the display panel in Structure Example 1. Here, only different points from those of Structure Example 1 are described and the description of the same points as Structure Example 1 is omitted.

A display panel which can be used in a display device of one embodiment of the present invention is a display panel in which a plurality of pixels and a plurality of auxiliary electrodes are provided in a display portion, each pixel includes a light-emitting element and a transistor, the light-emitting element includes a lower electrode, an upper electrode, and an EL layer between the lower electrode and the upper electrode, and the auxiliary electrode is in contact with the upper electrode between adjacent lower electrodes.

A display panel shown inFIG. 11Ahas a structure in which subpixels of four colors of R, G, B, and Y express one color.FIG. 11Cshows an example of the arrangement of the subpixels of R, G, B, and Y. The cross-sectional view of the display portion804inFIG. 11Ais taken along the dashed-dotted line Z1-Z2inFIG. 11C.

As in the display panel shown inFIG. 11A, the light-emitting element830includes an optical adjustment layer832between the lower electrode831and the EL layer833. A light-transmitting conductive material is preferably used for the optical adjustment layer832. Owing to the combination of the coloring layer and a microcavity structure utilizing the optical adjustment layer, light with high color purity can be extracted from the display device of one embodiment of the present invention. The thickness of the optical adjustment layer may be varied depending on the color of the sub-pixel. InFIG. 11A, an optical adjustment layer832R of the subpixel R and an optical adjustment layer832B of the subpixel B are shown.

The display panel inFIG. 11Aincludes a spacer823over the insulating layer821. The spacer823can adjust the distance between the substrate701and the substrate711.

The display panel inFIG. 11Aincludes an overcoat849covering the coloring layer845and the light-blocking layer847. The space between the light-emitting element830and the overcoat849is filled with the adhesive layer822.

In the display panel that can be used in the display device of one embodiment of the present invention, the transparent portion is adjacent to the display portion and provided along the sides of the display portion. In particular, in the case where the size of the display panel is large, it is required that a region not overlapping with the transparent portion include a contact region where an upper electrode (in this embodiment, the upper electrode835) common to pixels in the display portion is connected to a wiring in the vicinity of the display portion supplied with a power supply voltage. In the case where a conductive layer forming the upper electrode has high electric resistance, there is a concern that luminance of light emitted from a pixel apart from the contact region in the display portion be lowered by a voltage drop of the upper electrode.

The display panel shown inFIG. 11Aincludes, between pixels, an auxiliary electrode860for suppressing the voltage drop of the upper electrode835. The auxiliary electrode860is preferably formed of conductive materials whose electric resistance is lower than that of the upper electrode835.

The conductive layer forming the auxiliary electrode860, the lower electrode831, and the like are preferably formed at the same time because a process can be shortened. InFIG. 11A, the auxiliary electrode860is formed of a conductive material of the lower electrode831and a conductive material of the optical adjustment layer832.

Here, a method of forming the auxiliary electrode860will be described.FIGS. 11B and 11Cshow examples of a top view of sub-pixels R, G, B, and Y in the display portion804.FIG. 11Bis a top view at the time of finishing the formation of the lower electrode831.FIG. 11Cis a top view at the time of finishing the formation of the optical adjustment layer832, the insulating layer821, and the spacer823after the state shown inFIG. 11B. Note that components such as the transistor820which are formed before the formation of the lower electrode831are not shown inFIGS. 11B and 11C.

The auxiliary electrode860can be provided so as to fill a space between sub-pixels. For example, the auxiliary electrode860may be provided in a net-like shape so as to surround the lower electrode831in each sub-pixel, or may be provided in a plurality of lines (or stripes) in a space in one direction between adjacent lower electrodes831.

The auxiliary electrode860forming one line is preferably continuous because the electric resistance of the upper electrode835can be further reduced.FIG. 11Bshows an example in which a conductive layer860ais provided in a line. Note that here, the conductive layer860ais formed of the conductive layer used for forming the lower electrode831.

The auxiliary electrode860is in contact with the upper electrode835so as to be electrically connected to the upper electrode835. Therefore, in the case where EL layers833are formed by a separate coloring method, the EL layers833are not formed over the auxiliary electrode860, and the upper electrode835is formed over the auxiliary electrode860, whereby the auxiliary electrode860and the upper electrode835can be in contact with each other.

In this embodiment, the EL layers833are formed also on the auxiliary electrode860because the EL layers833are formed without using a separate coloring method. Therefore, a method for forming the upper electrode835so that a part of a surface of the auxiliary electrode860is not covered with the EL layer833and the part is covered with the upper electrode835is required.

FIG.11D1is an enlarged view of the auxiliary electrode860. The auxiliary electrode860has a stacked-layer structure of the conductive layer860aand a conductive layer860b. In the structure, the area of a bottom surface of the conductive layer860bis larger than the area of a top surface of the conductive layer860a, and a part of the conductive layer860bextends beyond the conductive layer860a.

When the auxiliary electrode860has such a structure, the conductive layer860bserves as eaves in forming the EL layer833. Therefore, the EL layer833is not formed on a part of a side surface of the conductive layer860a, so that the part of the side surface can be exposed. Furthermore, the upper electrode835is formed by a formation method which has lower anisotropy than a formation method for forming the EL layer833. Thus, the upper electrode835can be formed on the side surface of the conductive layer860a, and the conductive layer860aand the upper electrode835can be in contact with each other.

Note that in a process of manufacturing the display panel, a film lower than the conductive layer860amight be etched in etching the conductive layer860aor the conductive layer860b. In the case where a region in contact with an end portion of a lower surface of the conductive layer860ais etched in the film, the EL layer833is less likely to be formed on the side surface of the conductive layer860ain forming the EL layer833.

FIG.11D2is a cross-sectional view of the auxiliary electrode860in the case where a part of an insulating layer817bin contact with the end portion of the lower surface of the conductive layer860ais etched. In this case, the voltage drop of the upper electrode835can be suppressed more effectively than in the case of FIG.11D1.

InFIG. 11C, a portion which is surrounded by a dashed line and is not hatched is covered with the insulating layer821. In other words, regions surrounded by a solid line except the spacer823(a part of the optical adjustment layer832and a part of the conductive layer860b) coincide with opening portions formed in the insulating layer821. Here, the conductive layer860band the optical adjustment layer832are formed of the same conductive layer.

InFIG. 11C, the opening portion is formed in the insulating layer821so that a part of the auxiliary electrode860between a plurality of lower electrodes831is exposed. The size of the opening portion can be adjusted as appropriate depending on the electric resistance of the upper electrode835and the area of the display portion804. The width of the auxiliary electrode860, i.e., the length in a direction in which pixels are adjacent to each other with the auxiliary electrode860provided therebetween can be adjusted as appropriate depending on the electric resistance of the upper electrode835and the area of the display portion804.

Described below is a method for checking whether the auxiliary electrode860in the display panel performs its function, i.e., whether the side surface of the auxiliary electrode860is in contact with the upper electrode835as shown in FIG.11D1or FIG.11D2.

In the display portion804, a wiring (hereinafter referred to as a measurement wiring) electrically connected to the auxiliary electrodes860extending in one direction in a stripe is connected to one terminal (hereinafter referred to as a terminal A) included in the FPC808. One terminal included in the FPC808electrically connected to the upper electrode835is referred to as a terminal B.

When an electric resistance value between the terminal A and the terminal B is greater than or equal to 100Ω and less than or equal to 10 kΩ, the auxiliary electrode860can be regarded as being in contact with the upper electrode835in the display portion804. Note that the lower limit of the electric resistance value may vary depending on the materials of the auxiliary electrode860, the material of the upper electrode835, and a material and a length of the measurement wiring.

Correction circuits may be provided in pixels to suppress variation in current flowing in the light-emitting elements830in the pixels. Specifically, a plurality of transistors and/or a plurality of capacitors may be provided in each sub-pixel so that variation in current flowing in the transistors820each having a source electrode or a drain electrode connected to the lower electrode831through a conductive layer856is suppressed in different sub-pixels of the same color. The variation in current is due to variation in the thickness of a semiconductor layer of the transistor820in some cases. For example, a transistor870and a capacitor871shown inFIG. 11Amay have a function of correcting variation in current flowing in the transistor820.

FIG. 12,FIGS. 13A and 13B,FIGS. 14A and 14B,FIGS. 15A and 15B, andFIGS. 16A and 16Bshow examples of a pixel circuit including the above-described correction circuit.

A pixel circuit shown inFIG. 12includes six transistors (transistors M1to M6), three capacitors (capacitors C1to C3), and the light-emitting element830. A wiring S1, a wiring S2, and wirings G1to G6are electrically connected to the pixel circuit shown inFIG. 12. Note that as the transistors M1to M6, for example, n-channel transistors can be used.

For example, the wirings G1to G4shown inFIG. 12are electrically connected to the scan line driver circuit in the operating circuit portion806. For example, the wiring S1shown inFIG. 12is electrically connected to the signal line driver circuit in the operating circuit portion806. For example, the wiring G5, the wiring G6, and the wiring S2shown inFIG. 12are electrically connected to a constant voltage source.

For example, the transistor820inFIG. 11Acan serve as the transistor M6. For example, the transistor870inFIG. 11Acan serve as any one of the transistors M1to M5. For example, the capacitor871inFIG. 11Acan serve as any one of the capacitors C1to C3.

A pixel circuit shown inFIG. 13Aincludes six transistors (M7to M12), a capacitor C4, and the light-emitting element830. The pixel circuit shown inFIG. 13Ais electrically connected to wirings S3and S4and wirings G7to G11. Note that as the transistors M7to M12, for example, n-channel transistors can be used. Alternatively, p-channel transistors (M13to M18) may be used instead of the transistors M7to M12, as shown inFIG. 13B.

A pixel circuit shown inFIG. 14Ahas a structure in which a transistor M19is added to the pixel circuit shown inFIG. 13A. The pixel circuit shown inFIG. 14Ais electrically connected to wirings G12and G13. The wirings G11and G12may be electrically connected to each other. Note that as the transistor M19, for example, an n-channel transistor can be used.

A pixel circuit shown inFIG. 14Bhas a structure in which a transistor M20is added to the pixel circuit shown inFIG. 13B. The pixel circuit shown inFIG. 14Bis electrically connected to the wirings G12and G13. The wirings G11and G12may be electrically connected to each other. Note that as the transistor M20, for example, a p-channel transistor can be used.

A pixel circuit shown inFIG. 15Aincludes six transistors (M21to M26), the capacitor C4, and the light-emitting element830. The pixel circuit shown inFIG. 15Ais electrically connected to wirings S5to S7and wirings G14to G16. The wirings G14to G16may be electrically connected to each other. Note that as the transistors M21to M26, for example, n-channel transistors can be used. Alternatively, p-channel transistors (M27to M32) may be used instead of the transistors M21to M26, as shown inFIG. 15B.

A pixel circuit shown inFIG. 16Aincludes two transistors (transistors M33and M34), two capacitors (capacitors C5and C6), and the light-emitting element830. The pixel circuit shown inFIG. 16Ais electrically connected to wirings S8to S9and wirings G17to G19. With the configuration of the pixel circuit shown inFIG. 16A, the pixel circuit shown inFIG. 16Acan be driven by a voltage inputting current driving method (also referred to as CVCC). Note that as the transistors M33and M34, for example, n-channel transistors can be used. Alternatively, p-channel transistors (M35and M36) may be used instead of the transistors M33to M34, as shown inFIG. 16B.

Structure Example 3

FIG. 9Bis a plan view of the display panel, andFIG. 17Ais an example of a cross-sectional view taken along the dashed-dotted line A3-A4inFIG. 9B. The display panel in Structure Example 3 is a top-emission display device using a separate coloring method.

The display panel inFIG. 17Aincludes the substrate701, the adhesive layer703, the insulating layer705, a plurality of transistors, the conductive layer857, the insulating layer815, the insulating layer817, a plurality of light-emitting elements, the insulating layer821, the spacer823, the adhesive layer822, the insulating layer715, and the substrate711. The adhesive layer822, the insulating layer715, and the substrate711transmit visible light.

In the display panel inFIG. 17A, the connector825is positioned over the insulating layer815. The connector825is connected to the conductive layer857through an opening provided in the insulating layer815. Moreover, the connector825is connected to the FPC808. The FPC808and the conductive layer857are electrically connected to each other with the connector825provided therebetween.

Structure Example 4

FIG. 9Bis a plan view of the display panel, andFIG. 17Bis an example of a cross-sectional view taken along the dashed-dotted line A3-A4inFIG. 9B. The display panel in Structure Example 4 is a bottom-emission display panel using a color filter method.

The display panel inFIG. 17Bincludes the substrate701, the adhesive layer703, the insulating layer705, a plurality of transistors, the conductive layer857, the insulating layer815, the coloring layer845, the insulating layer817a, the insulating layer817b, the conductive layer856, a plurality of light-emitting elements, the insulating layer821, the adhesive layer822, and the substrate711. The substrate701, the adhesive layer703, the insulating layer705, the insulating layer815, the insulating layer817a, and the insulating layer817btransmit visible light.

The display portion804includes the transistor820, the transistor824, and the light-emitting element830over the insulating layer705. The light-emitting element830includes the lower electrode831over the insulating layer817b, the EL layer833over the lower electrode831, and the upper electrode835over the EL layer833. The lower electrode831is electrically connected to a source electrode or a drain electrode of the transistor820. An end portion of the lower electrode831is covered with the insulating layer821. The upper electrode835preferably reflects visible light. The lower electrode831transmits visible light. The coloring layer845that overlaps with the light-emitting element830can be provided anywhere; for example, the coloring layer845may be provided between the insulating layers817aand817bor between the insulating layers815and817a.

In the operating circuit portion806, a plurality of transistors are provided over the substrate701with the adhesive layer703and the insulating layer705provided therebetween. InFIG. 17B, two of the transistors included in the operating circuit portion806is illustrated.

The insulating layer705is preferably highly resistant to moisture, in which case impurities such as water can be prevented from entering the light-emitting element830, the transistor820, or the transistor824, leading to higher reliability of the display panel.

The conductive layer857is electrically connected to an external electrode through which a signal or a potential from the outside is transmitted to the operating circuit portion806. Here, an example in which the FPC808is provided as the external electrode is described. Here, an example is described in which the conductive layer857is formed using the same material and the same step(s) as those of the conductive layer856.

Examples of Materials and Formation Method

Next, materials and the like that can be used for the display panel or the light-emitting panel are described. Note that description of the components already described in this specification and the like is omitted in some cases.

For each of the substrates, a material such as glass, quartz, an organic resin, a metal, or an alloy can be used. The substrate through which light is extracted from the light-emitting element is formed using a material which transmits the light.

In particular, a flexible substrate is preferably used. For example, an organic resin; or glass, a metal, or an alloy that is thin enough to have flexibility can be used.

An organic resin, which has a specific gravity smaller than that of glass, is preferably used for the flexible substrate, in which case the display panel can be lightweight as compared with the case where glass is used.

The substrate is preferably formed using a material with high toughness. In that case, a display panel with high impact resistance that is less likely to be broken can be provided. For example, when an organic resin substrate or a thin metal or alloy substrate is used, the display panel can be lightweight and unlikely to be broken as compared with the case where a glass substrate is used.

A metal material and an alloy material, which have high thermal conductivity, are preferable because they can easily conduct heat to the whole substrate and accordingly can prevent a local temperature rise in the display panel. The thickness of a substrate using a metal material or an alloy material is preferably greater than or equal to 10 μm and less than or equal to 200 μm, further preferably greater than or equal to 20 μm and less than or equal to 50 μm.

There is no particular limitation on a material of the metal substrate or the alloy substrate, but it is preferable to use, for example, aluminum, copper, nickel, or a metal alloy such as an aluminum alloy or stainless steel.

Furthermore, when a material with high thermal emissivity is used for the substrate, the surface temperature of the display panel can be prevented from rising, leading to inhibition of breakage or a decrease in reliability of the display panel. For example, the substrate may have a stacked-layer structure of a metal substrate and a layer with high thermal emissivity (the layer can be formed using a metal oxide or a ceramic material, for example).

As the substrate having flexibility and a light-transmitting property, a plastic substrate that is formed as a film, for example, a plastic substrate made from polyimide (PI), an aramid, polyethylene terephthalate (PET), polyethersulfone (PES), polyethylene naphthalate (PEN), polycarbonate (PC), nylon, polyetheretherketone (PEEK), polysulfone (PSF), polyetherimide (PEI), polyarylate (PAR), polybutylene terephthalate (PBT), a silicone resin, and the like, or a glass substrate can be used. The substrate may include a fiber or the like (e.g., a prepreg). Furthermore, the substrate is not limited to the resin film, and a transparent nonwoven fabric formed by processing pulp into a continuous sheet, a sheet including an artificial spider'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's thread fiber may be used.

The flexible substrate may have a stacked-layer structure in which a hard coat layer (e.g., a silicon nitride layer) by which a surface of the device is protected from damage, a layer which can disperse pressure (e.g., an aramid resin layer), or the like is stacked over a layer of any of the above-mentioned materials.

The flexible substrate may be formed by stacking a plurality of layers. When a glass layer is used, a barrier property against water and oxygen can be improved and thus a highly reliable display panel can be provided.

For example, a flexible substrate in which a glass layer, an adhesive layer, and an organic resin layer are stacked from the side closer to a light-emitting element can be used. The thickness of the glass layer is greater than or equal to 20 μm and less than or equal to 200 μm, preferably greater than or equal to 25 μm and less than or equal to 100 μm. With such a thickness, the glass layer can have both a high barrier property against water and oxygen and high flexibility. The thickness of the organic resin layer is greater than or equal to 10 μm and less than or equal to 200 μm, preferably greater than or equal to 20 μm and less than or equal to 50 μm. By providing such an organic resin layer outside the glass layer, occurrence of a crack or a break in the glass layer can be inhibited and mechanical strength can be improved. With the substrate that includes such a composite material of a glass material and an organic resin, a highly reliable flexible display panel can be provided.

Here, a method for forming a flexible display panel is described.

For convenience, a structure including a pixel and a driver circuit, a structure including an optical member such as a color filter, a structure including a touch sensor, or a structure including a functional member is referred to as an element layer. An element layer includes a display element, for example, and may include a wiring electrically connected to a display element or an element such as a transistor used in a pixel or a circuit in addition to the display element.

Here, a support provided with an insulating surface over which an element layer is formed is called a base material.

As a method for forming an element layer over a flexible base material, there are a method in which an element layer is formed directly over a base material, and a method in which an element layer is formed over a supporting base material that is different from the base material and has stiffness and then the element layer is separated from the supporting base material and transferred to the base material.

In the case where a material of the base material can withstand heating temperature in the process for forming the element layer, it is preferred that the element layer be formed directly over the base material, in which case a manufacturing process can be simplified. At this time, the element layer is preferably formed in a state where the base material is fixed to the supporting base material, in which case the transfer of the element layer in a device and between devices can be easy.

In the case of employing the method in which the element layer is formed over the supporting base material and then transferred to the base material, first, a separation layer and an insulating layer are stacked over a supporting base material, and then the element layer is formed over the insulating layer. Then, the element layer is separated from the supporting base material and then transferred to the base material. At this time, a material is selected such that separation at an interface between the supporting base material and the separation layer, at an interface between the separation layer and the insulating layer, or in the separation layer occurs. With such a method, the element layer can be formed at temperatures higher than the upper temperature limit of the base material, which improves the reliability of the display panel.

For example, it is preferable that stacked layers of a layer including a high-melting-point metal material, such as tungsten, and a layer including an oxide of the metal material be used as the separation layer, and stacked layers of a plurality of layers as the insulating layer, such as a silicon nitride layer and a silicon oxynitride layer be used over the separation layer. By using a high-melting-point metal material, a high-temperature process can be performed to form the element layer, resulting in high reliability. For example, impurities contained in the element layer can be further reduced, and the crystallinity of a semiconductor or the like included in the element layer can be further increased. For the base material, any of the above flexible materials can be preferably used.

Examples of the separation include peeling off by application of mechanical power, removal of the separation layer by etching, or separation by dripping of a liquid into part of the separation interface to penetrate the entire separation interface.

The separation layer is not necessarily provided in the case where separation can occur at an interface between the supporting base material and the insulating layer. For example, glass may be used as the supporting base material, an organic resin such as polyimide may be used as the insulating layer, a separation trigger may be formed by locally heating part of the organic resin by laser light or the like, and separation may be performed at an interface between the glass and the insulating layer. Alternatively, it is possible that a layer containing a material with high thermal conductivity (e.g., a metal or a semiconductor) is provided between the supporting base material and the insulating layer containing an organic resin, and this layer is heated by current so that separation easily occurs, and then separation is performed. In this case, the insulating layer containing an organic resin can also be used as the base material.

As the adhesive layer, a variety of curable resins such as a reactive curable resin, a thermosetting resin, an anaerobic resin, and a photo curable resin such as an ultraviolet curable resin can be used. Examples of such resins include an epoxy resin, an acrylic resin, a silicone resin, a phenol resin, a polyimide resin, an imide resin, a polyvinyl chloride (PVC) resin, a polyvinyl butyral (PVB) resin, an ethylene vinyl acetate (EVA) resin, and the like. In particular, a material with low moisture permeability, such as an epoxy resin, is preferable. Alternatively, a two-component-mixture-type resin may be used. Further alternatively, an adhesive sheet or the like may be used.

Furthermore, the resin may include a drying agent. For example, a substance which adsorbs moisture by chemical adsorption, such as an oxide of an alkaline earth metal (e.g., calcium oxide or barium oxide), can be used. Alternatively, a substance that adsorbs moisture by physical adsorption, such as zeolite or silica gel, may be used. The drying agent is preferably included, in which case entry of impurities such as moisture into the light-emitting element can be inhibited and the reliability of the display panel can be improved.

In addition, a filler with a high refractive index or a light scattering member is mixed into the resin, in which case the efficiency of light extraction from the light-emitting element can be improved. For example, titanium oxide, barium oxide, zeolite, zirconium, or the like can be used.

Insulating films with high resistance to moisture are preferably used for the insulating layer705and the insulating layer715. Alternatively, the insulating layer705and the insulating layer715preferably have a function of preventing diffusion of impurities to a light-emitting element.

As an insulating film having an excellent moisture-proof property, a film containing nitrogen and silicon (e.g., a silicon nitride film or a silicon nitride oxide film), a film containing nitrogen and aluminum (e.g., an aluminum nitride film), or the like can be used. Alternatively, a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, or the like can be used.

For example, the water vapor transmittance of the insulating film having an excellent moisture-proof property is lower than or equal to 1×10−5[g/(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 display panel, it is necessary that at least one of the insulating layers705and715, which is on the light-emitting surface side, transmit light emitted from the light-emitting element. In the case where the display panel includes the insulating layers705and715, one of the insulating layers705and715, which transmits light emitted from the light-emitting element, preferably has higher average transmittance than the other in a wavelength of 400 nm or more and 800 nm or less.

The insulating layers705and715each preferably include oxygen, nitrogen, and silicon. The insulating layers705and715each preferably include, for example, silicon oxynitride. Moreover, the insulating layers705and715each preferably include silicon nitride or silicon nitride oxide. It is preferable that the insulating layers705and715be each formed using a silicon oxynitride film and a silicon nitride film, which are in contact with each other. The silicon oxynitride film and the silicon nitride film are alternately stacked so that antiphase interference occurs more often in a visible region, whereby the stack can have higher transmittance of light in the visible region.

There is no particular limitation on the structure of the transistor in the display panel. For example, a forward staggered transistor or an inverted staggered transistor may be used. Furthermore, a top-gate transistor or a bottom-gate transistor may be used. A semiconductor material used for the transistors is not particularly limited, and for example, silicon, germanium, or an organic semiconductor can be used. Alternatively, an oxide semiconductor containing at least one of indium, gallium, and zinc, such as an In—Ga—Zn-based metal oxide, may be used.

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 layer705can serve as a base film of the transistor.

As the light-emitting element, a self-luminous element can be used, and an element whose luminance is controlled by current or voltage is included in the category of the light-emitting element. For example, a light-emitting diode (LED), an organic EL element, an inorganic EL element, or the like can be used.

The light-emitting element may have any of a top emission structure, a bottom emission structure, and a dual emission structure. A conductive film that transmits visible light is used as the electrode through which light is extracted. A conductive film that reflects visible light is preferably used as the electrode through which light is not extracted.

The conductive film that transmits visible light can be formed using, for example, indium oxide, indium tin oxide (ITO), indium zinc oxide, zinc oxide (ZnO), or zinc oxide to which gallium is added. Alternatively, a film of a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or titanium; an alloy containing any of these metal materials; a nitride of any of these metal materials (e.g., titanium nitride); or the like can be formed thin so as to transmit light. Alternatively, a stacked film of any of the above materials can be used as the conductive layer. For example, a stacked film of ITO and an alloy of silver and magnesium is preferably used, in which case conductivity can be increased. Further alternatively, graphene or the like may be used.

For the conductive film that reflects visible light, for example, a metal material, such as aluminum, gold, platinum, silver, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, or palladium or an alloy including any of these metal materials can be used. Lanthanum, neodymium, germanium, or the like may be added to the metal material or the alloy. Furthermore, an alloy containing aluminum (an aluminum alloy) such as an alloy of aluminum and titanium, an alloy of aluminum and nickel, an alloy of aluminum and neodymium, or an alloy of aluminum, nickel, and lanthanum (Al—Ni—La), or an alloy containing silver such as an alloy of silver and copper, an alloy of silver, palladium, and copper (Ag—Pd—Cu, also referred to as APC), or an alloy of silver and magnesium can be used for the conductive film. An alloy of silver and copper is preferable because of its high heat resistance. Moreover, a metal film or a metal oxide film is stacked on an aluminum alloy film, whereby oxidation of the aluminum alloy film can be suppressed. Examples of a material for the metal film or the metal oxide film are titanium and titanium oxide. Alternatively, the conductive film having a property of transmitting visible light and a film containing any of the above metal materials may be stacked. For example, a stacked film of silver and ITO or a stacked film of an alloy of silver and magnesium and ITO can be used.

The lower electrode831, the upper electrode835, and the conductive layers forming the auxiliary electrode860(the conductive layers860aand860b) can be formed of the conductive film that transmits visible light or the conductive film that reflects visible light.

The electrodes may be formed separately by an evaporation method or a sputtering method. Alternatively, a discharging method such as an ink-jet method, a printing method such as a screen printing method, or a plating method may be used.

When a voltage higher than the threshold voltage of the light-emitting element is applied between the lower electrode831and the upper electrode835, holes are injected to the EL layer833from the anode side and electrons are injected to the EL layer833from the cathode side. The injected electrons and holes are recombined in the EL layer833and a light-emitting substance contained in the EL layer833emits light.

The EL layer833includes at least a light-emitting layer. In addition to the light-emitting layer, the EL layer833may 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 layer833, 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 layer833can 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 element830may 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 element830preferably 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 layer833may include a plurality of light-emitting layers. In the EL layer833, 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 element830may be a single element including one EL layer or a tandem element in which EL layers are stacked with a charge generation layer provided therebetween.

The light-emitting element is preferably provided between a pair of insulating films having an excellent moisture-proof property. In that case, entry of an impurity such as moisture into the light-emitting element can be inhibited, leading to inhibition of a decrease in the reliability of the display panel.

As the insulating layer815and the insulating layer816, for example, an inorganic insulating film such as a silicon oxide film, a silicon oxynitride film, or an aluminum oxide film can be used. Note that the insulating layer815and the insulating layer816may be formed using different materials. As the insulating layer817, the insulating layer817a, and the insulating layer817b, an organic material such as polyimide, acrylic, polyamide, polyimide amide, or a benzocyclobutene-based resin can be used, for example. Alternatively, a low-dielectric constant material (a low-k material) or the like can be used. Furthermore, each insulating layer may be formed by stacking a plurality of insulating films.

The insulating layer821is 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 layer821be formed using a photosensitive resin material to have an opening portion over the lower electrode831so that a side wall of the opening portion is formed as an inclined surface with a continuous curvature.

There is no particular limitation on the method for forming the insulating layer821; 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 spacer823can 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 spacer823containing a conductive material is electrically connected to the upper electrode835, a potential drop due to the resistance of the upper electrode835can be inhibited. The spacer823may have either a tapered shape or an inverse tapered shape.

For example, a conductive layer functioning as an electrode or a wiring of the transistor, an auxiliary electrode of the light-emitting element, or the like, which is used for the display panel, can be formed to have a single-layer structure or a stacked-layer structure using any of metal materials such as molybdenum, titanium, chromium, tantalum, tungsten, aluminum, copper, neodymium, and scandium, and an alloy material containing any of these elements. Alternatively, the conductive layer may be formed using a conductive metal oxide. As the conductive metal oxide, indium oxide (e.g., In2O3), tin oxide (e.g., SnO2), ZnO, ITO, indium zinc oxide (e.g., In2O3—ZnO), or any of these metal oxide materials in which silicon oxide is contained can be used.

The coloring layer is a colored layer that transmits light in a specific wavelength range. For example, a color filter for transmitting light in a red, green, blue, or yellow wavelength range can be used. Each coloring layer is formed in a desired position with any of various materials by a printing method, an inkjet method, an etching method using a photolithography method, or the like. In a white sub-pixel, a resin such as a transparent resin or a white resin may be provided so as to overlap with the light-emitting element.

The light-blocking layer is provided between the adjacent coloring layers. The light-blocking layer blocks light emitted from an adjacent light-emitting element to inhibit color mixture between adjacent light-emitting elements. Here, the coloring layer is provided such that its end portion overlaps with the light-blocking layer, whereby light leakage can be reduced. As the light-blocking layer, a material that can block light from the light-emitting element can be used; for example, a black matrix is formed using a resin material containing a metal material, pigment, or dye. Note that it is preferable to provide the light-blocking layer in a region other than the display portion, such as a driver circuit portion, in which case undesired leakage of guided light or the like can be inhibited.

Furthermore, an overcoat covering the coloring layer and the light-blocking layer may be provided. The overcoat can prevent an impurity and the like contained in the coloring layer from being diffused into the light-emitting element. The overcoat is formed with a material that transmits light emitted from the light-emitting element; for example, an inorganic insulating film such as a silicon nitride film or a silicon oxide film, an organic insulating film such as an acrylic film or a polyimide film can be used, and further, a stacked-layer structure of an organic insulating film and an inorganic insulating film may be employed.

In the case where upper surfaces of the coloring layer and the light-blocking layer are coated with a material of the adhesive layer, a material which has high wettability with respect to the material of the adhesive layer is preferably used as the material of the overcoat. For example, an oxide conductive film such as an ITO film or a metal film such as an Ag film which is thin enough to transmit light is preferably used as the overcoat.

As the connector, any of a variety of anisotropic conductive films (ACF), anisotropic conductive pastes (ACP), and the like can be used.

In this specification and the like, a display element, a display panel which is a panel including a display element, a light-emitting element, and a light-emitting panel which is a panel including a light-emitting element can employ various modes or can include various elements. A display element, a display panel, a light-emitting element, or a light-emitting panel may include a display medium whose contrast, luminance, reflectivity, transmittance, or the like is changed by electrical or magnetic effect, such as an EL element (e.g., an EL element including organic and inorganic materials, an organic EL element, or an inorganic EL element), an LED (e.g., a white LED, a red LED, a green LED, or a blue LED), a transistor (a transistor which emits light depending on current), an electron emitter, a liquid crystal element, electronic ink, an electrophoretic element, a grating light valve (GLV), a plasma display panel (PDP), a display element including micro electro mechanical systems (MEMS), a digital micromirror device (DMD), a digital micro shutter (DMS), an interferometric modulator display (IMOD) element, an MEMS shutter display element, optical interference type MEMS display element, an electrowetting element, a piezoelectric ceramic display, and a display element including a carbon nanotube. Note that examples of a display panel having an EL element include an EL display. Examples of a display panel having an electron emitter include a field emission display (FED) and an SED-type flat panel display (SED: surface-conduction electron-emitter display). Examples of a display panel having a liquid crystal element include a liquid crystal display (e.g., a transmissive liquid crystal display, a transflective liquid crystal display, a reflective liquid crystal display, a direct-view liquid crystal display, or a projection liquid crystal display). Examples of a display panel having electronic ink, ELECTRONIC LIQUID POWDER (registered trademark), or an electrophoretic element include electronic paper. In the case of a transflective liquid crystal display or a reflective liquid crystal display, some of or all of pixel electrodes function as reflective electrodes. For example, some or all of pixel electrodes are formed to contain aluminum or silver. Furthermore, in such a case, a memory circuit such as an SRAM can be provided under the reflective electrodes, leading to lower power consumption. Note that in the case of using an LED, graphene or graphite may be provided under an electrode or a nitride semiconductor of the LED. Graphene or graphite may be a multilayer film in which a plurality of layers are stacked. As described above, provision of graphene or graphite enables easy formation of a nitride semiconductor film thereover, such as an n-type GaN semiconductor layer including crystals. Furthermore, a p-type GaN semiconductor layer including crystals or the like can be provided thereover, and thus the LED can be formed. Note that an AlN layer may be provided between the n-type GaN semiconductor layer including crystals and graphene or graphite. The GaN semiconductor layers included in the LED may be formed by MOCVD. Note that when the graphene is provided, the GaN semiconductor layers included in the LED can also be formed by a sputtering method.

For example, in this specification and the like, an active matrix method in which an active element (a non-linear element) is included in a pixel or a passive matrix method in which an active element is not included in a pixel can be used.

In the active matrix method, not only a transistor but also a variety of active elements can be used. For example, an MIM (metal insulator metal), a TFD (thin film diode), or the like can also be used. Since such an element has few numbers of manufacturing steps, manufacturing cost can be reduced or yield can be improved. Alternatively, since the size of these elements is small, the aperture ratio can be improved, so that power consumption can be reduced or higher luminance can be achieved.

Since an active element is not used in the passive matrix method, the number of manufacturing steps can be reduced, so that manufacturing cost can be reduced or the yield can be improved. Alternatively, since an active element is not used in the passive matrix method, the aperture ratio can be improved, so that power consumption can be reduced or higher luminance can be achieved, for example.

Note that the light-emitting panel of one embodiment of the present invention may be used as a display panel or as a lighting panel. For example, it may be used as a light source such as a backlight or a front light, that is, a lighting panel for a display panel.

As described above, by using the display panel including the transparent portion described as an example in this embodiment, a large-sized display device in which a joint portion of the display portions is hardly seen and display unevenness is reduced can be obtained.

This embodiment can be combined with any other embodiment as appropriate.

In this embodiment, a touch panel that can be used in a display device of one embodiment of the present invention will be described with reference to drawings. Note that the above description can be referred to for the components of the touch panel, which are similar to those of the display panel described in Embodiment 2. Although a touch panel including a light-emitting element is described as an example in this embodiment, one embodiment of the present invention is not limited thereto. For example, a touch panel including another element (e.g., a display element), the example of which is shown in Embodiment 2, can also be used in the display device of one embodiment of the present invention.

Structure Example 1

FIG. 18Ais a top view of the touch panel.FIG. 18Bis a cross-sectional view taken along the dashed-dotted line A-B and the dashed-dotted line C-D inFIG. 18A.FIG. 18Cis a cross-sectional view taken along the dashed-dotted line E-F inFIG. 18A.

A touch panel390illustrated inFIG. 18Aincludes a display portion301(serving also as an input portion), a scan line driver circuit303g(1), an imaging pixel driver circuit303g(2), an image signal line driver circuit303s(1), and an imaging signal line driver circuit303s(2).

The display portion301includes a plurality of pixels302and a plurality of imaging pixels308.

The pixel302includes 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 circuit303g(1) can supply selection signals to the pixels302.

The image signal line driver circuit303s(1) can supply image signals to the pixels302.

A touch sensor can be formed using the imaging pixels308. Specifically, the imaging pixels308can sense a touch of a finger or the like on the display portion301.

The imaging pixels308include photoelectric conversion elements and imaging pixel circuits.

The imaging pixel circuits can drive photoelectric conversion elements. The imaging pixel circuits are electrically connected to wirings through which control signals are supplied. The imaging pixel circuits are also electrically connected to wirings through which power supply potentials are supplied.

Examples of the control signal include a signal for selecting an imaging pixel circuit from which a recorded imaging signal is read, a signal for initializing an imaging pixel circuit, and a signal for determining the time it takes for an imaging pixel circuit to sense light.

The imaging pixel driver circuit303g(2) can supply control signals to the imaging pixels308.

The imaging signal line driver circuit303s(2) can read out imaging signals.

As illustrated inFIGS. 18B and 18C, the touch panel390includes the substrate701, the adhesive layer703, the insulating layer705, the substrate711, the adhesive layer713, and the insulating layer715. The substrates701and711are bonded to each other with an adhesive layer360.

The substrate701and the insulating layer705are bonded to each other with the adhesive layer703. The substrate711and the insulating layer715are bonded to each other with the adhesive layer713.

Embodiment 2 can be referred to for materials used for the substrates, the adhesive layers, and the insulating layers.

Each of the pixels302includes the sub-pixel302R, a sub-pixel302G, and a sub-pixel302B (seeFIG. 18C). The sub-pixel302R includes a light-emitting module380R, the sub-pixel302G includes a light-emitting module380G, and the sub-pixel302B includes a light-emitting module380B.

For example, the sub-pixel302R includes the light-emitting element350R and the pixel circuit. The pixel circuit includes a transistor302tthat can supply electric power to the light-emitting element350R. Furthermore, the light-emitting module380R includes the light-emitting element350R and an optical element (e.g., a coloring layer367R that transmits red light).

The light-emitting element350R includes a lower electrode351R, an EL layer353, and an upper electrode352, which are stacked in this order (seeFIG. 18C).

The EL layer353includes a first EL layer353a, an intermediate layer354, and a second EL layer353b, which are stacked in this order.

Note that a microcavity structure can be provided for the light-emitting module380R 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 module380R, for example, includes the adhesive layer360that is in contact with the light-emitting element350R and the coloring layer367R.

The coloring layer367R is positioned in a region overlapping with the light-emitting element350R. Accordingly, part of light emitted from the light-emitting element350R passes through the adhesive layer360and the coloring layer367R and is emitted to the outside of the light-emitting module380R as indicated by an arrow inFIG. 18B or 18C.

The touch panel390includes a light-blocking layer367BM. The light-blocking layer367BM is provided so as to surround the coloring layer (e.g., the coloring layer367R).

The touch panel390includes an anti-reflective layer367ppositioned in a region overlapping with the display portion301. As the anti-reflective layer367p, a circular polarizing plate can be used, for example.

The touch panel390includes an insulating layer321. The insulating layer321covers the transistor302tand the like. Note that the insulating layer321can be used as a layer for covering unevenness caused by the pixel circuits and the imaging pixel circuits. An insulating layer on which a layer that can inhibit diffusion of impurities to the transistor302tand the like is stacked can be used as the insulating layer321.

The touch panel390includes a partition328that overlaps with an end portion of the lower electrode351R. In addition, a spacer329that controls the distance between the substrate701and the substrate711is provided on the partition328.

The image signal line driver circuit303s(1) includes a transistor303tand a capacitor303c. 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 inFIG. 18B, the transistor303tmay include a second gate304over the insulating layer321. The second gate304may be electrically connected to a gate of the transistor303t, or different potentials may be supplied to these gates. Alternatively, if necessary, the second gate304may be provided for a transistor308t, the transistor302t, or the like.

The imaging pixels308each include a photoelectric conversion element308pand an imaging pixel circuit. The imaging pixel circuit can sense light received by the photoelectric conversion element308p. The imaging pixel circuit includes the transistor308t.

For example, a PIN photodiode can be used as the photoelectric conversion element308p.

The touch panel390includes a wiring311through which a signal is supplied. The wiring311is provided with a terminal319. Note that an FPC309through which a signal such as an image signal or a synchronization signal is supplied is electrically connected to the terminal319. Note that a printed wiring board (PWB) may be attached to the FPC309.

Note that transistors such as the transistors302t,303t, and308tcan be formed in the same process. Alternatively, the transistors may be formed in different processes.

Structure Example 2

FIGS. 19A and 19Bare perspective views of a touch panel505A. Note thatFIGS. 19A and 19Billustrate only main components for simplicity.FIG. 20Ais a cross-sectional view taken along the dashed-dotted line G-H inFIG. 19A.

As illustrated inFIGS. 19A and 19B, the touch panel505A includes a display portion501, the scan line driver circuit303g(1), a touch sensor595, and the like. Furthermore, the touch panel505A includes the substrate701, the substrate711, and a substrate590.

The touch panel505A includes a plurality of pixels and a plurality of wirings311. The plurality of wirings311can supply signals to the pixels. The plurality of wirings311are led to a peripheral portion of the substrate701, and part of the plurality of wirings311form the terminal319. The terminal319is electrically connected to an FPC509(1).

The touch panel505A includes the touch sensor595and a plurality of wirings598. The plurality of wirings598are electrically connected to the touch sensor595. The plurality of wirings598are led to a peripheral portion of the substrate590, and part of the plurality of wirings598form a terminal. The terminal is electrically connected to an FPC509(2). Note that inFIG. 19B, electrodes, wirings, and the like of the touch sensor595provided on the back side of the substrate590(the side facing the substrate701) are indicated by solid lines for clarity.

As the touch sensor595, for example, a capacitive touch sensor can be used. Examples of the capacitive touch sensor include a surface capacitive touch sensor and a projected capacitive touch sensor. An example of using a projected capacitive touch sensor is described here.

Examples of the projected capacitive touch sensor include a self capacitive touch sensor and a mutual capacitive touch sensor, which differ mainly in the driving method. The use of a mutual capacitive type is preferred because multiple points can be sensed simultaneously.

Note that a variety of sensors that can sense the closeness or the contact of a sensing target such as a finger can be used as the touch sensor595.

The projected capacitive touch sensor595includes electrodes591and electrodes592. The electrodes591are electrically connected to any of the plurality of wirings598, and the electrodes592are electrically connected to any of the other wirings598.

The electrodes592each 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 inFIGS. 19A and 19B.

The electrodes591each have a quadrangular shape and are arranged in a direction intersecting with the direction in which the electrodes592extend. Note that the plurality of electrodes591is not necessarily arranged in the direction orthogonal to one electrode592and may be arranged to intersect with one electrode592at an angle of less than 90 degrees.

The wiring594intersects with the electrode592. The wiring594electrically connects two electrodes591between which the electrode592is positioned. The intersecting area of the electrode592and the wiring594is 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 sensor595can be reduced.

Note that the shapes of the electrodes591and the electrodes592are not limited to the above-mentioned shapes and can be any of a variety of shapes. For example, the plurality of electrodes591may be provided so that space between the electrodes591are reduced as much as possible, and a plurality of electrodes592may be provided with an insulating layer sandwiched between the electrodes591and the electrodes592and may be spaced apart from each other to form a region not overlapping with the electrodes591. In that case, between two adjacent electrodes592, it is preferable to provide a dummy electrode which is electrically insulated from these electrodes, whereby the area of a region having a different transmittance can be reduced.

Note that a more specific structure example of the touch sensor595will be described later.

As illustrated inFIG. 20A, the touch panel505A includes the substrate701, the adhesive layer703, the insulating layer705, the substrate711, the adhesive layer713, and the insulating layer715. The substrates701and711are bonded to each other with the adhesive layer360.

An adhesive layer597bonds the substrate590to the substrate711so that the touch sensor595overlaps with the display portion501. The adhesive layer597transmits light.

The electrodes591and the electrodes592are formed using a conductive material that transmits light. As a light-transmitting conductive material, a conductive oxide such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, or zinc oxide to which gallium is added can be used. Note that a film including graphene may be used as well. The film including graphene can be formed, for example, by reducing a film including graphene oxide. As a reducing method, a method with application of heat or the like can be employed.

The resistance of a material used for conductive films such as the electrodes591, the electrodes592, and the wiring594, i.e., a wiring and an electrode in the touch panel, is preferably low. Examples of the material include ITO, indium zinc oxide, ZnO, silver, copper, aluminum, a carbon nanotube, and graphene. Alternatively, a metal nanowire including a number of conductors with an extremely small width (for example, a diameter of several nanometers) may be used. Note that a metal nanowire, a carbon nanotube, graphene, or the like may be used for an electrode of the display element, e.g., a pixel electrode or a common electrode because of its high transmittance.

The electrodes591and the electrodes592may be formed by depositing a light-transmitting conductive material on the substrate590by a sputtering method and then removing an unnecessary portion by a variety of patterning technique such as photolithography.

The electrodes591and the electrodes592are covered with an insulating layer593. Furthermore, openings reaching the electrodes591are Ruined in the insulating layer593, and the wiring594electrically connects the adjacent electrodes591. A light-transmitting conductive material can be favorably used as the wiring594because the aperture ratio of the touch panel can be increased. Moreover, a material with higher conductivity than the conductivities of the electrodes591and the electrodes592can be favorably used for the wiring594because electric resistance can be reduced.

Note that an insulating layer covering the insulating layer593and the wiring594may be provided to protect the touch sensor595.

Furthermore, a connection layer599electrically connects the wirings598to the FPC509(2).

The display portion501includes 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 inFIGS. 20A and 20B.

For example, a semiconductor layer containing an oxide semiconductor, amorphous silicon, or the like can be used in the transistor302tand the transistor303tillustrated inFIG. 20A.

For example, a semiconductor layer containing polycrystalline silicon that is obtained by crystallization process such as laser annealing can be used in the transistor302tand the transistor303tillustrated inFIG. 20B.

A structure in the case of using top-gate transistors is illustrated inFIG. 20C.

For example, a semiconductor layer including polycrystalline silicon, a single crystal silicon film that is transferred from a single crystal silicon substrate, or the like can be used in the transistor302tand the transistor303tillustrated inFIG. 20C.

Structure Example 3

FIGS. 21A to 21Care cross-sectional views of a touch panel505B. The touch panel505B described in this embodiment is different from the touch panel505A in Structure Example 2 in that received image data is displayed on the side where the transistors are provided, that the touch sensor is provided on the substrate701side of the display portion, and that the FPC509(2) is provided on the same side as the FPC509(1). Different structures will be described in detail below, and the above description is referred to for the other similar structures.

The coloring layer367R is positioned in a region overlapping with the light-emitting element350R. The light-emitting element350R illustrated inFIG. 21Aemits light to the side where the transistor302tis provided. Accordingly, part of light emitted from the light-emitting element350R passes through the coloring layer367R and is emitted to the outside of the light-emitting module380R as indicated by an arrow inFIG. 21A.

The touch panel505B includes the light-blocking layer367BM on the light extraction side. The light-blocking layer367BM is provided so as to surround the coloring layer (e.g., the coloring layer367R).

The touch sensor595is provided not on the substrate711side but on the substrate701side (seeFIG. 21A).

The adhesive layer597bonds the substrate590to the substrate701so that the touch sensor595overlaps with the display portion. The adhesive layer597transmits light.

Note that a structure in the case of using bottom-gate transistors in the display portion501is illustrated inFIGS. 21A and 21B.

For example, a semiconductor layer containing an oxide semiconductor, amorphous silicon, or the like can be used in the transistor302tand the transistor303tillustrated inFIG. 21A.

For example, a semiconductor layer containing polycrystalline silicon can be used in the transistor302tand the transistor303tillustrated inFIG. 21B.

A structure in the case of using top-gate transistors is illustrated inFIG. 21C.

For example, a semiconductor layer containing polycrystalline silicon, a single crystal silicon film that is transferred, or the like can be used in the transistor302tand the transistor303tillustrated inFIG. 21C.

Structural Example of Touch Sensor

A more specific structure example of the touch sensor595is described below with reference to drawings.

FIG. 22Ais a schematic top view of the touch sensor595. The touch sensor595includes a plurality of electrodes531, a plurality of electrodes532, a plurality of wirings541, and a plurality of wirings542over a substrate590. The substrate590is provided with an FPC550which is electrically connected to each of the plurality of wirings541and the plurality of wirings542.

FIG. 22Bshows an enlarged view of a region surrounded by a dashed dotted line inFIG. 22A. The electrodes531are each in the form of a series of rhombic electrode patterns aligned in a lateral direction of this figure. The rhombic electrode patterns aligned in a line are electrically connected to each other. The electrodes532are also each in the form of a series of rhombic electrode patterns aligned in a longitudinal direction in this figure and the rhombic electrode patterns aligned in a line are electrically connected. Part of the electrode531and part of the electrode532overlap and intersect with each other. At this intersection portion, an insulator is sandwiched in order to avoid an electrical short-circuit between the electrode531and the electrode532.

As shown inFIG. 22C, the electrodes532may form a plurality of island-shape rhombic electrodes533and bridge electrodes534. The plurality of island-shape rhombic electrodes533are aligned in a longitudinal direction in this figure, and two adjacent electrodes533are electrically connected to each other by the bridge electrode534. Such a structure makes it possible that the electrodes533and the electrodes531can be formed at the same time by processing the same conductive film. This can prevent variations in the thickness of these films, and can prevent the resistance value and the light transmittance of each electrode from varying from place to place. Note that although the electrodes532include the bridge electrodes534here, the electrodes531may have such a structure.

As shown inFIG. 22D, a design in which rhombic electrode patterns of the electrodes531and532shown inFIG. 22Bare hollowed out and only edge portions are left may be used. At that time, when the electrodes531and the electrodes532are too small in width for the users to see, the electrodes531and the electrodes532can be formed using a light-blocking material such as a metal or an alloy, as described later. In addition, either the electrodes531or the electrodes532shown inFIG. 22Dmay include the above bridge electrodes534.

One of the electrodes531is electrically connected to one of the wirings541. One of the electrodes532is electrically connected to one of the wirings542.

When a touch panel is formed in such a manner that the touch sensor595is stacked over a display surface of the display panel, a light-transmitting conductive material is preferably used for the electrodes531and the electrodes532. In the case where a light-transmitting conductive material is used for the electrodes531and the electrodes532and light from the display panel is extracted through the electrodes531or the electrodes532, it is preferable that a conductive film containing the same conductive material be arranged between the electrodes531and the electrodes532as a dummy pattern. Part of a space between the electrodes531and the electrodes532is filled with the dummy pattern, which can reduce variation in light transmittance. As a result, unevenness in luminance of light transmitted through the touch sensor595can be reduced.

As a light-transmitting conductive material, a conductive oxide such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, or zinc oxide to which gallium is added can be used. Note that a film including graphene can be used as well. The film including graphene can be formed, for example, by reducing a film containing graphene oxide. As a reducing method, a method with application of heat or the like can be employed.

Further, a metal film or an alloy film which is thin enough to have a light-transmitting property can be used. For example, a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or titanium, or an alloy material containing any of these metal materials can be used. Alternatively, a nitride of the metal material or the alloy material (e.g., titanium nitride), or the like may be used. Alternatively, a stacked film in which two or more of conductive films containing the above materials are stacked may be used.

For the electrodes531and the electrodes532, a conductive film which is processed to be too thin to see by the users may be used. Such a conductive film is processed into a lattice shape (a mesh shape), for example, which makes it possible to achieve high conductivity and high visibility of the display device. It is preferable that the conductive film have a portion in which the width is greater than or equal to 30 nm and less than or equal to 100 μm, preferably greater than or equal to 50 nm and less than or equal to 50 μm, and further preferably greater than or equal to 50 nm and less than or equal to 20 μm. In particular, the conductive film having the pattern width of 10 μm or less is extremely difficult to see by the users, which is preferable.

As examples, enlarged schematic views of part of the electrodes531or the electrodes532(part in a circle formed by a dashed-dotted line inFIG. 22B) are shown inFIGS. 23A to 23D.FIG. 23Ashows an example of the case in which a lattice-shape conductive film561is used. The lattice-shape conductive film561is preferably placed so as not to overlap the display element included in the display device because light from the display device is not blocked. In that case, it is preferable that the direction of the lattice be provided so as to be the same as the direction of the display element arrangement and that the pitch of the lattice be an integer multiple of the pitch of the display element arrangement.

FIG. 23Bshows an example of a lattice-shape conductive film562, which is processed so as to be provided with triangle openings. Such a structure makes it possible to further reduce the resistance compared with the structure shown inFIG. 23A.

In addition, a conductive film563, which has an irregular pattern shape, may be used as shown inFIG. 23C. Such a structure can prevent generation of moiré when overlapping with the display portion of the display device. Note that “moiré” refers to a fringe pattern created by diffraction or interference when external light or the like passes through or external light is reflected by narrow conductive films or the like spaced uniformly.

Conductive nanowires may be used for the electrodes531and the electrodes532.FIG. 23Dshows an example of the case in which nanowires564are used. The nanowires564are dispersed at appropriate density so as to be in contact with the adjacent nanowires, which can form a two-dimensional network; therefore, a conductive film with extremely high light-transmitting property can be provided. For example, a nanowire which has a mean value of the diameters of greater than or equal to 1 nm and less than or equal to 100 nm, preferably greater than or equal to 5 nm and less than or equal to 50 nm, further preferably greater than or equal to 5 nm and less than or equal to 25 nm can be used. As the nanowire564, a metal nanowire such as an Ag nanowire, a Cu nanowire, and an Al nanowire, a carbon nanotube, or the like can be used. In the case of using an Ag nanowire, for example, light transmittance of 89% or more and a sheet resistance of 40 ohm/square or more and 100 ohm square or less can be achieved.

Although examples in which a plurality of rhombuses are aligned in one direction are shown inFIG. 22Aand the like as top surface shapes of the electrodes531and the electrodes532, the shapes of the electrodes531and the electrodes532are not limited thereto and can have various top surface shapes such as a belt shape (a rectangular shape), a belt shape having a curve, and a zigzag shape. In addition, although the above shows the electrodes531and the electrodes532are arranged to be perpendicular to each other, they are not necessarily arranged to be perpendicular and the angle formed by two of the electrodes may be less than 90°.

FIGS. 24A to 24Cillustrate examples of the case where electrodes536and electrodes537, which have a top surface shape of thin lines, are used instead of the electrodes531and the electrodes532.FIG. 24Ashows an example in which linear electrodes536and537are arranged so as to form a lattice shape.

FIG. 24Bshows an example in which the electrodes536and the electrodes537have a top surface shape of a zigzag shape. As shown inFIG. 24B, the electrodes536and the electrodes537are arranged so as not to cross the straight-line portions at the centers but so as to place the centers of the straight-line portions in different positions from each other; therefore, the length of closely facing parallel parts of the electrodes536and the electrodes537can be longer. This is preferable because the capacitance between the electrodes can be increased and the sensitivity can be increased. Alternatively, as shown inFIG. 24C, the electrodes536and the electrodes537are arranged so as to have a design in which part of the straight-line portion of a zigzag shape is projected, which can increase the capacitance between the electrodes because the length of the parts facing each other can be longer even when the centers of the straight-line portions are placed in the same position.

FIGS. 25A to 25Cshow enlarged views of a region surrounded by a dashed dotted line inFIG. 24B, andFIGS. 25D to 25Fshow enlarged views of a region surrounded by a dashed dotted line inFIG. 24C. In these drawings, the electrodes536, the electrodes537, and intersection portions538at which the electrodes536and the electrodes537intersect are illustrated. The straight-line portions of the electrodes536and the electrodes537shown inFIGS. 25A and 25Dmay have a serpentine shape that meanders with angled corners as shown inFIGS. 25B and 25Eor may have a serpentine shape that continuously meanders as shown inFIGS. 25C and 25F.

Structure Example 4

As illustrated inFIG. 26, a touch panel500TP includes a display portion500and an input portion600that overlap each other.FIG. 27is a cross-sectional view taken along the dashed-dotted line Z1-Z2inFIG. 26.

Individual components included in the touch panel500TP are described below. Note that these components cannot be clearly distinguished and one component also serves as another component or include part of another component in some cases. Note that the touch panel500TP in which the input portion600overlaps with the display portion500is also referred to as a touch panel.

The input portion600includes a plurality of sensing units602arranged in a matrix. The input portion600also includes a selection signal line GL, a control line RES, a signal line DL, and the like.

The selection signal line GL and the control line RES are electrically connected to the plurality of sensing units602that are arranged in the row direction (indicated by the arrow R inFIG. 26). The signal line DL is electrically connected to the plurality of sensing units602that are arranged in the column direction (indicated by the arrow C inFIG. 26).

The sensing unit602senses an object that is close thereto or in contact therewith and supplies a sensing signal. For example, the sensing unit602senses, 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 unit602senses, for example, a change in capacitance between the sensing unit602and an object close thereto or an object in contact therewith.

Note that when an object having a dielectric constant higher than that of the air, such as a finger, comes close to a conductive film in the air, the capacitance between the finger and the conductive film changes. The sensing unit602can 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 unit602is provided with a sensor circuit. The sensor circuit is electrically connected to the selection signal line GL, the control line RES, the signal line DL, or the like.

The sensor circuit includes a transistor, a sensor element, and/or the like. For example, a conductive film and a capacitor electrically connected to the conductive film can be used for the sensor circuit. A capacitor and a transistor electrically connected to the capacitor can also be used for the sensor circuit.

For example, a capacitor650including an insulating layer653, and a first electrode651and a second electrode652between which the insulating layer653is provided can be used for the sensor circuit (seeFIG. 27). Specifically, the voltage between the electrodes of the capacitor650changes when an object approaches the conductive film which is electrically connected to one electrode of the capacitor650.

The sensing unit602includes a switch that can be turned on or off in accordance with a control signal. For example, a transistor M12can be used as the switch.

A transistor which amplifies a sensing signal can be used in the sensing unit602.

Transistors manufactured through the same process can be used as the transistor that amplifies a sensing signal and the switch. This allows the input portion600to be provided through a simplified process.

The sensing unit602includes a plurality of window portions667arranged in a matrix. The window portions667transmit visible light. A light-blocking layer BM may be provided between the window portions667.

A coloring layer is provided in a position overlapping with the window portion667in the touch panel500TP. 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 layer367B transmitting blue light, a coloring layer367G transmitting green light, and a coloring layer367R transmitting red light can be used. Alternatively, a coloring layer transmitting yellow light or white light may be used.

The display portion500includes the plurality of pixels302arranged in a matrix. The pixel302is positioned so as to overlap with the window portions667of the input portion600. The pixels302may be arranged at higher resolution than the sensing units602. Each pixel has the same structure as Structure Example 1; thus, description is omitted.

The touch panel500TP includes the input portion600that includes the plurality of sensing units602arranged in a matrix and the window portions667transmitting visible light, the display portion500that includes the plurality of pixels302overlapping with the window portions667, and the coloring layers between the window portions667and the pixels302. Each of the sensing units includes a switch that can reduce interference in another sensing unit.

Thus, sensing data obtained by each sensor unit can be supplied together with the positional information of the sensor unit. In addition, sensing data can be supplied in relation to the positional data of the pixel for displaying an image. In addition, the sensor unit which does not supply the sensing data is not electrically connected to a signal line, whereby interference with the sensor unit which supplies a sensing signal can be reduced. Consequently, the novel touch panel500TP that is highly convenient or highly reliable can be provided.

For example, the input portion600of the touch panel500TP can sense sensing data and supply the sensing data together with the positional data. Specifically, a user of the touch panel500TP 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 portion600.

The input portion600can sense a finger or the like that comes close to or is in contact with the input portion600and 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 portion600can 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 portion600of the touch panel500TP 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 panel500TP can drive the sensing unit and supply sensing data independently of its size. The touch panel500TP 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 panel500TP 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 panel500TP.

The display portion500of the touch panel500TP can be supplied with display data. For example, an arithmetic unit can supply the display data.

In addition to the above structure, the touch panel500TP can have the following structure.

The touch panel500TP may include a driver circuit603gor a driver circuit603d. In addition, the touch panel500TP may be electrically connected to an FPC1.

The driver circuit603gcan supply selection signals at predetermined timings, for example. Specifically, the driver circuit603gsupplies selection signals to the selection signal lines GL row by row in a predetermined order. Any of a variety of circuits can be used as the driver circuit603g. For example, a shift register, a flip flop circuit, a combination circuit, or the like can be used.

The driver circuit603dsupplies sensing data on the basis of a sensing signal supplied from the sensing unit. Any of a variety of circuits can be used as the driver circuit603d. 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 circuit603d. In addition, an analog-to-digital converter circuit that converts a sensing signal into a digital signal may be provided in the driver circuit603d.

The FPC1supplies a timing signal, a power supply potential, or the like and is supplied with a sensing signal.

The touch panel500TP may include a driver circuit503g, a driver circuit503s, a wiring311, and a terminal319. In addition, the touch panel500TP may be electrically connected to an FPC2.

In addition, a protective layer670that prevents damage and protects the touch panel500TP may be provided. For example, a ceramic coat layer or a hard coat layer can be used as the protective layer670. Specifically, a layer containing aluminum oxide or a UV curable resin can be used.

In the case of a transflective liquid crystal display or a reflective liquid crystal display, some of or all of pixel electrodes function as reflective electrodes. For example, some or all of pixel electrodes are formed to contain aluminum, silver, or the like.

Furthermore, a memory circuit such as an SRAM can be provided under the reflective electrodes, leading to lower power consumption. A structure suitable for employed display elements can be selected from among a variety of structures of pixel circuits.

The touch panel described in this embodiment can be used instead of the display panel100included in the display device10in Embodiment 1. In this case, a touch panel with a structure in which a plurality of FPCs connected to the touch panel are extracted from the same side, such as the touch panel390and the touch panel505B, can be preferably used. Note that in the case where a touch panel is used instead of the display panel100, the display device10can be referred to as an input/output device.

The adhesive layer107that bonds the plurality of touch panels to the substrate106is preferably provided so that the top surfaces of the touch sensors595(or the input portions600) of these touch panels are level with each other and the top surfaces are parallel to the substrate106. The distances between the surface of the input/output device (i.e., the surface of the substrate106) and the touch sensors595(or the input portions600) of the touch panels are made the same, whereby location dependence (also called in-plane variation) of detection sensitivity can be reduced.

This embodiment can be combined with any other embodiment as appropriate.

Example

In this example, an example in which a display device of one embodiment of the present invention was manufactured is described.

The display device20includes four display panels80arranged in a matrix of two rows and two columns (two display panels in the horizontal direction and two display panels in the longitudinal direction). Table 1 shows the specifications of the display panel80in this example.FIG. 28Ais a photograph of the display panel80displaying an image.

FIG. 29is a photograph of the display device20displaying an image. The horizontal direction inFIG. 29corresponds to the X-axis direction inFIG. 1AandFIG. 4A, and the longitudinal direction inFIG. 29corresponds to the Y-axis direction inFIG. 1AandFIG. 4A. The display device20includes four plates90, four stages91, four driver circuits62, four adjusting units63, and the frame21.

FIGS. 30A and 30Bare photographs of one of four component groups60in the display device20. In each component group60, the display panel80and the plate90are fixed to each other and connected to the stage91.FIG. 30Ais a photograph of the component group60from the diagonally front side. The display, portion41of the display panel80is shown inFIG. 30A.FIG. 30Bis a photograph of the component group60from the diagonally rear side.

As shown inFIG. 30A, the display panel80includes the transparent portion82in a position adjacent to two sides of the display portion41. As shown inFIG. 30B, the display panel80is fixed to the plate90so that transparent portion82and a part of the display portion41extend beyond two sides of the plate90. In the display device20having such a structure, display portions41of the four display panels80can be arranged seamlessly, and an image or video without unnatural seams can be displayed on a display portion11C used as one display area (seeFIG. 29). In this example, the width of the transparent portion82is approximately 2 mm (seeFIG. 28B).FIG. 28Bis an enlarged photograph of a region surrounded by a dashed line inFIG. 28A.

As shown inFIG. 30B, the alignment of the plate90and the stage91in the horizontal direction and the longitudinal direction can be performed precisely using the depression51, the fastening52, and the guide53of the plate90. In the display device20, the stage91is fixed to the frame21through the adjusting unit63. As the adjusting unit63, the combination of the X-axis stage, the Y-axis stage, and the goniometer stage is used as described in Embodiment 1. In the display device20having such a structure, the positions of the display panels80can be adjusted with high precision so that the display portions41of the four display panels80are seamlessly arranged to be parallel and that the positional shift of display on the display portions41of the adjacent display panels80does not occur.FIG. 31Ais an enlarged photograph of a region in the vicinity of the joint portion of the display portions in the display device20displaying an image. InFIG. 31A, the joint portion of the display portions41is included in a region surrounded by a dashed line. It is shown fromFIG. 31Athat the display portions41of the four display panels80in the display device20are arranged so that the positional shift of display does not occur along the joint portion.

Note that the first surface of the plate90may be provided with a fixing instrument. In the case where the display panel80includes a chip on film (COF), the COF can be fixed to the first surface of the plate90using the fixing instrument.FIG. 34is a photograph of the plate90in which the fixing instrument54is provided in the vicinity of the convexly curved surface of the first surface and the display panel80fixed to the plate90. The fixing instrument54includes a member54aand a member54b. A material of the member54ais not particularly limited. The member54bis preferably faulted of an insulator. The member54ais formed of a material similar to that of the plate90. The member54bis formed of plastic. By fixing the COF of the display device20to the member54bwith a screw or the like, the display panel80can be prevented from being broken when the plate90to which the display panel80is fixed is carried.

The driver circuits62can correct variation in display performance of the display panels80because of having a function of adjusting color tone, luminance, or the like of display of the display panels80. Thus, the display portion11C of the display device20can perform display with high display quality in which variation in color tone, luminance, or the like is suppressed.

FIG. 31Bis a photograph of the display device20from the diagonally front side with respect to the display portion11C. As shown inFIG. 31B, the first portion44of the display panel80is bent to the rear surface side of the display surface of the display panel80along the convexly curved surface of the plate50. Thus, the driver circuit62provided on the rear surface side of the display panel80can be easily connected to the external electrode46. In addition, the external electrode46or the like does not hinder overlapping of the display panels80, so that the display surface of the display portion11C can be made almost flat with few steps. Note that inFIG. 31B, the lower (rear) display panel is denoted by80a, whereas the upper (front) display panel is denoted by80b.

In the display device20, the display portion11C has a size of 27 inches diagonal (the size of the display portion41of one display panel80is 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. 32is a photograph of the display device10displaying an image. The display device10includes display panels80of this example arranged in a matrix of six rows and six columns (six display panels in each of the horizontal direction and the longitudinal direction).FIG. 33Ais a photograph of the rear side of the display surface of the display device10.FIG. 33Bis an enlarged photograph of a portion surrounded by a dotted line inFIG. 33A.FIG. 33Bis a photograph showing a state in which the cables64connected to the driver circuits62inFIG. 33Aare removed.

The display device10includes 36 plates90, 36 stages91, 36 driver circuits62, 36 adjusting units63, and the frame21. The display device10also includes four video signal dividers22and two video output units23(not shown). In this example, an uncompressed disk recorder is used as the video output unit23. Note that in the display device10, a display portion11D has a size of 81 inches diagonal and the number of effective pixels is 7680×4320 (8K).

In this example, as the light-emitting element included in the display portion41, a tandem (stack) organic EL element emitting white light was used. The light-emitting element has a top emission structure. Light from the light-emitting element is extracted outside through a color filter.

As the transistor, a transistor including a c-axis aligned crystalline oxide semiconductor (CAAC-OS) was used. Unlike amorphous semiconductor, the CAAC-OS has few defect states, so that the reliability of the transistor can be improved. In addition, because laser crystallization is not needed for formation of a CAAC-OS, a uniform film can be formed even over a large-sized glass substrate or the like. Moreover, since the CAAC-OS does not have a grain boundary, stress that is caused by bending a flexible display panel does not easily make a crack in a CAAC-OS film.

A CAAC-OS is an oxide semiconductor having c-axis alignment in a direction substantially perpendicular to the film surface. It has been found that oxide semiconductors have a variety of crystal structures other than a single-crystal structure. An example of such structures is a nano-crystal (nc) structure, which is an aggregate of nanoscale microcrystals. The crystallinity of a CAAC-OS structure is lower than that of a single-crystal structure and higher than that of an nc structure.

In this example, a channel-etched transistor including an In—Ga—Zn-based oxide was used. The transistor was fabricated over a glass substrate at a process temperature lower than 500° C.

As shown inFIG. 29andFIG. 32, in one embodiment of the present invention, a large-sized display device in which a joint portion of display portions is hardly recognized by a user was able to be obtained.

At least part of this example can be implemented in combination with any of the embodiments described in this specification as appropriate.

REFERENCE NUMERALS

This application is based on Japanese Patent Application serial no. 2014-206873 filed with Japan Patent Office on Oct. 8, 2014, Japanese Patent Application serial no. 2014-219086 filed with Japan Patent Office on Oct. 28, 2014, Japanese Patent Application serial no. 2014-240213 filed with Japan Patent Office on Nov. 27, 2014, and Japanese Patent Application serial no. 2015-043931 filed with Japan Patent Office on Mar. 5, 2015, the entire contents of which are hereby incorporated by reference.