Display device

Abstract

To prevent damage in a flexible display, and to provide a display device achieving both thickness and flexibility.SOLUTION: The display device comprises a display panel including a display element. The display panel includes a first film, a second film, and an adhesion layer. The adhesion layer is positioned between the first film and the second film, and has function of bonding the first film to the second film. The display element is supported by the first film. The display panel has 0.01 times or more and less than one time flexure elastic modulus relative to its tensile elastic modulus.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] One aspect of the present invention relates to a display device, and more particularly to a display device having a flexible display.

[0002] Note that one embodiment of the present invention is not limited to the above technical field. Examples of the technical field of one embodiment of the present invention disclosed in this specification and the like include a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, an electronic device, a lighting device, an input device, an input / output device, a driving method thereof, or a manufacturing method thereof. A semiconductor device refers to any device that can function by utilizing semiconductor characteristics. [Background technology]

[0003] Flexible displays that can be curved have been actively developed. Representative display elements used in flexible displays include light-emitting elements such as organic electroluminescence (EL) elements and liquid crystal elements.

[0004] The basic structure of an organic EL element is a layer containing a light-emitting organic compound sandwiched between a pair of electrodes. By applying a voltage to this element, light can be emitted from the light-emitting organic compound. A display device using such an organic EL element does not require a light source such as a backlight, so that a thin, lightweight, high-contrast, and low-power display device can be realized.

[0005] For example, Patent Document 1 discloses a flexible light-emitting device to which an organic EL element is applied. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2014-197522 A Summary of the Invention [Problem to be solved by the invention]

[0007] Flexible displays are extremely thin compared to conventional displays, so there is a problem that it is difficult to increase their mechanical strength. In particular, when a flexible display is used as a touch panel, the flexible display may be damaged if a finger or stylus touches the display surface hard. In addition, if a protective film is attached to the display surface of the flexible display to prevent damage, the overall thickness increases, which reduces the flexibility.

[0008] An object of one embodiment of the present invention is to prevent damage to a flexible display. Another object is to provide a display device which has both thickness and flexibility. Another object is to provide a highly reliable display device or electronic device. Another object is to provide a display device or electronic device having a novel structure.

[0009] Note that the description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily solve all of these problems. Note that problems other than these can be extracted from the description of the specification, drawings, claims, etc. [Means for solving the problem]

[0010] One embodiment of the present invention is a display device having a display panel including a display element. The display panel has a first film, a second film, and a first adhesive layer. The first adhesive layer is located between the first film and the second film, and has a function of bonding the first film and the second film together. The display element is supported by the first film. The display panel has a flexural modulus of elasticity that is 0.01 times or more and less than 1 times the tensile modulus of elasticity.

[0011] Another embodiment of the present invention is a display device having a display panel including a display element. The display panel has a first film, a second film, and a first adhesive layer. The first adhesive layer is located between the first film and the second film, and has a function of bonding the first film and the second film. The display element is supported by the first film. The display panel has a flexural modulus of elasticity that is 0.01 times or more and less than 1 times the tensile modulus of elasticity. The first adhesive layer has viscoelasticity and is more stretchable than the first film and the second film.

[0012] Another embodiment of the present invention is a display device having a display panel including a display element. The display panel has a first film, a second film, and a first adhesive layer. The first adhesive layer is located between the first film and the second film, and has a function of bonding the first film and the second film together. The display element is supported by the first film. The display panel has a flexural modulus of elasticity that is 0.01 times or more and less than 1 times the tensile modulus of elasticity. When a part of the display panel is curved, the display panel deforms such that an end surface of the first film and an end surface of the second film are misaligned relative to each other.

[0013] In the above, it is preferable that the display panel has a flexural modulus of elasticity that is 0.01 to 0.2 times the tensile modulus of elasticity.

[0014] In the above, the second film preferably has a function as a touch sensor or a circular polarizing plate.

[0015] In the above, the first film preferably contains one or more of an epoxy resin, an aramid resin, an acrylic resin, an imide resin, an amide resin, an amide-imide resin, and glass.

[0016] In the above, the second film preferably contains one or more of a urethane resin, an acrylic resin, a silicone resin, a fluororesin, an olefin resin, a vinyl resin, a styrene resin, an amide resin, an ester resin, and an epoxy resin.

[0017] In the above, the first adhesive layer preferably contains a rubber-like or gel-like material containing silicone, acrylic resin, or urethane resin.

[0018] The above may further include a second adhesive layer and a third film. The second adhesive layer overlaps the first adhesive layer via the second film, and has a function of bonding the second film and the third film. Furthermore, it is preferable that the second adhesive layer has viscoelasticity and is more elastic than the first film and the second film. It is also preferable that the third film contains one or more of urethane resin, acrylic resin, silicone resin, fluororesin, olefin resin, vinyl resin, styrene resin, amide resin, ester resin, and epoxy resin.

[0019] Another aspect of the present invention is an electronic device including any one of the display devices described above and a protective cover. The protective cover has a first portion having a flat surface and a second portion adjacent to the first portion and having a curved surface, and is provided to cover the display surface of the display panel. The display panel has a portion held by the protective cover along the first portion and the second portion.

[0020] Another aspect of the present invention is an electronic device having any one of the display devices described above, a first support, a second support, and a connecting portion. The first support and the second support are connected by the connecting portion. The display panel has a first portion supported by the first support, a second portion supported by the second support, and a third portion located between the first portion and the second portion. The connecting portion is configured to curve the third portion of the display panel so that the display surface is convex or concave, allowing the first support and the second support to overlap.

[0021] Another aspect of the present invention is an electronic device having the display device according to any one of the above, a first support, a second support, a third support, a first connecting portion, and a second connecting portion. The first support and the second support are connected by the first connecting portion. The second support and the third support are connected by the second connecting portion. The display panel has a first portion supported by the first support, a second portion supported by the second support, a third portion supported by the third support, a fourth portion located between the first portion and the second portion, and a fifth portion located between the second portion and the third portion. The first connecting portion is configured to bend the fourth portion of the display panel in a convex shape so that the first support and the second support can be overlapped. The second connecting portion is configured to bend the fifth portion of the display panel in a concave shape so that the second support and the third support can be overlapped. Effect of the Invention

[0022] According to one embodiment of the present invention, damage to a flexible display can be prevented. Alternatively, a display device having both thickness and flexibility can be provided. Alternatively, a display device or electronic device with high reliability can be provided. Alternatively, a display device or electronic device with a novel structure can be provided.

[0023] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these can be extracted from the description in the specification, drawings, claims, etc. [Brief description of the drawings]

[0024] [Figure 1] 1A to 1C show examples of the configuration of a display panel. [Diagram 2] 2A to 2C show examples of the configuration of a display panel. [Diagram 3] 3A and 3B show examples of the configuration of a display panel. [Figure 4] 4A to 4E show application examples of a display panel. [Diagram 5] 5A to 5D show application examples of a display panel. [Figure 6] 6A and 6B show an application example of a display panel. [Figure 7] 7A and 7B show an application example of a display panel. [Figure 8] 8A and 8B show an application example of a display panel. [Figure 9] 9A to 9C show configuration examples of a display device. [Figure 10] FIG. 10 shows an example of a cross-sectional configuration of a display device. [Figure 11] FIG. 11 shows an example of a cross-sectional configuration of a display device. [Figure 12] Figure 12A shows a block diagram of the display device, and Figures 12B and 12C show circuit diagrams. [Figure 13] Figures 13A, 13C, and 13D show circuit diagrams of the display device, and Figure 13B shows a timing chart. [Figure 14] 14A to 14E show examples of pixel configurations. [Figure 15] 15A to 15C show configuration examples of electronic devices. [Figure 16] 16A to 16E show configuration examples of electronic devices. [Figure 17] 17A to 17G show configuration examples of electronic devices. [Figure 18] 18A to 18D show configuration examples of electronic devices. [Figure 19] 19A and 19B show the measurement results of the tensile modulus and the flexural modulus in accordance with the embodiment. [Figure 20] 20A1 to 20C2 show micrographs of samples according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, the embodiments will be described with reference to the drawings. However, it will be easily understood by those skilled in the art that the embodiments can be implemented in many different ways, and that the modes and details can be changed in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the following embodiments.

[0026] In the configuration of the invention described below, the same parts or parts having similar functions are denoted by the same reference numerals in different drawings, and the repeated explanations are omitted. In addition, when referring to similar functions, the same hatch pattern may be used and no particular reference numeral may be used.

[0027] In addition, in each figure described in this specification, the size of each component, the thickness of a layer, or an area may be exaggerated for clarity, and therefore, the drawings are not necessarily limited to the scale.

[0028] In addition, ordinal numbers such as "first" and "second" in this specification are used to avoid confusion of components and do not limit the numbers.

[0029] In the following, expressions indicating directions such as "up" and "down" are basically used in accordance with the directions in the drawings. However, for the purpose of facilitating explanation, the directions indicated by "up" or "down" in the specification may not match those in the drawings. As an example, when explaining the stacking order (or formation order) of a laminate, even if the surface on the side where the laminate is provided (the surface to be formed, the supporting surface, the adhesive surface, the flat surface, etc.) is located above the laminate in the drawing, the direction may be expressed as "down" and the opposite direction as "up."

[0030] In this specification and the like, a display panel, which is one aspect of a display device, has a function of displaying (outputting) an image or the like on a display surface. Therefore, the display panel is one aspect of an output device.

[0031] In addition, in this specification, a display panel having a connector such as an FPC (Flexible Printed Circuit) or TCP (Tape Carrier Package) attached to the substrate, or a substrate having an IC mounted thereon using a COG (Chip On Glass) method or the like, may be referred to as a display panel module, display module, or simply a display panel.

[0032] In this specification and the like, a touch panel, which is one aspect of a display device, has a function of displaying an image or the like on a display surface and a function as a touch sensor that detects that a detectable object such as a finger or a stylus touches, presses, or approaches the display surface. Thus, the touch panel is one aspect of an input / output device.

[0033] The touch panel can also be called, for example, a display panel (or display device) with a touch sensor or a display panel (or display device) with a touch sensor function. The touch panel can have a display panel and a touch sensor panel. Alternatively, the touch panel can have a function as a touch sensor inside or on the surface of the display panel.

[0034] In addition, in this specification and the like, a touch panel substrate on which a connector and / or an IC are mounted may be referred to as a touch panel module, a display module, or simply a touch panel.

[0035] (Embodiment 1) In this embodiment, a display device according to one embodiment of the present invention will be described.

[0036] A display device according to one embodiment of the present invention includes a display panel including a display element. The display panel includes a first film, a second film, and an adhesive layer disposed between the first film and the second film. The adhesive layer functions to bond the first film and the second film.

[0037] The display element is provided so as to be supported by the first film, and therefore the first film can also be called a substrate or a support that supports the display element.

[0038] The second film functions as a protective film for protecting a display element. A part of the second film can function as a display surface of a display panel. The second film may also function as a sensor such as a touch sensor. The second film may also function as an optical member such as a circular polarizing plate.

[0039] A display panel according to one embodiment of the present invention is characterized in that the bending modulus is smaller than the tensile modulus. In particular, the bending modulus is 0.01 times or more and less than 1 times the tensile modulus, preferably 0.01 times or more and 0.5 times or less, more preferably 0.01 times or more and 0.2 times or less, and further preferably 0.01 times or more and 0.1 times or less. Note that the smaller the bending modulus of the display panel is compared to the tensile modulus, the more preferable it is, and the bending modulus of the display panel may be less than 0.01 times the tensile modulus.

[0040] In this specification, the flexural modulus refers to the Young's modulus calculated from a stress-strain curve (SS curve) measured by a bending test, and the tensile modulus refers to the Young's modulus calculated from a stress-strain curve (SS curve) measured by a tensile test.

[0041] The bending test can be performed based on or with reference to standards such as ISO178, JIS K7171, and ASTM D790. The tensile test can be performed based on or with reference to standards such as ISO527, JIS K7161, and JIS K7127.

[0042] First, when considering a single flexible film, the bending modulus and the tensile modulus are theoretically the same value. Next, in the case of a laminated film in which multiple flexible films are bonded together with an adhesive or the like, the bending modulus tends to be greater than the tensile modulus. That is, even if the films have the same thickness, the laminated film tends to be more difficult to bend than a single flexible film.

[0043] However, in the display panel according to one embodiment of the present invention, the flexural modulus is smaller than the tensile modulus, and therefore the display panel can be curved with a small force. In addition, by increasing the tensile modulus, the display panel can be provided with a feature that it is less likely to expand and contract in the stretching direction. As a result, even if the display panel is repeatedly bent and stretched, the display panel is less likely to expand and contract, and therefore damage to display elements and wiring constituting the display panel can be suppressed, and as a result, the durability of the display panel can be improved.

[0044] A display panel having such characteristics can be realized by providing a plurality of neutral surfaces in the display panel. More specifically, the display panel may have a laminated structure in which the neutral surface of the first film is located within the first film and the neutral surface of the second film is located within the second film when the display panel is curved.

[0045] A more preferred embodiment is to use a material (viscoelastic body) exhibiting viscoelasticity, which is a property that combines both viscosity and elasticity, as the adhesive layer that bonds the first film and the second film. A viscoelastic body has a property of being distorted when an external force is applied, and a property of the distortion becoming constant and the stress disappearing (becoming 0) when the applied external force is kept constant. In particular, it is preferable to use a material that is more viscous than elastic and can be deformed by a small force. For example, a viscoelastic body having an elastic modulus of 1 kPa to 1 MPa, preferably 5 kPa to 500 kPa, more preferably 10 kPa to 200 kPa, can be used as the adhesive layer.

[0046] In addition, the adhesive layer preferably has higher elasticity than the first film and the second film. More specifically, when the first film, the second film, and the adhesive layer are pulled with the same force, the adhesive layer preferably has the most stretchable property.

[0047] By using such a material for the adhesive layer, when an external force is applied to bend the display panel, the adhesive layer distorts to relieve the stress while adhering the first film and the second film. Therefore, the first film and the second film can bend in different neutral planes without expanding or contracting. As a result, the display panel can be bent with a very small force.

[0048] Furthermore, when the display panel is held in a curved state, the distortion of the adhesive layer is constant as described above, so that no restoring force is generated and the display panel can maintain its shape without the application of a large force. In particular, when the restoring forces of the first film and the second film are negligibly small, the display panel maintains its shape.

[0049] In addition, the display panel of one embodiment of the present invention has a characteristic that when an external force is applied to bend the display panel from a flat state to a predetermined curvature, and the state is maintained for a certain time, and then the external force is removed, the display panel slowly deforms over time (several seconds to several tens of seconds) so that the curvature becomes smaller due to the restoring forces of the first film and the second film, and returns to the original flat state. In addition, the display panel may not completely return to the original flat state.

[0050] In addition, by using a material exhibiting viscoelasticity for the adhesive layer, when an external force is applied from the display surface side of the display panel, the adhesive layer deforms and can appropriately relieve the stress. In other words, the adhesive layer functions as an impact absorbing layer, making it possible to suppress damage to the display elements and pixel circuits provided on the first film.

[0051] On the other hand, when the above-mentioned adhesive is used, the thicker the adhesive, the harder it is to bend the laminate, but in one embodiment of the present invention, the thicker the adhesive layer, the smaller the bending modulus can be. Since the adhesive layer is provided to cover the display element of the display panel, the thicker the adhesive layer, the better the function of protecting the display element, and the more reliable the display device can be realized.

[0052] A more specific example will be described below with reference to the drawings.

[0053] [Configuration example] 1A shows a schematic cross-sectional view of a display panel 10 according to one embodiment of the present invention. The display panel 10 has a film 11, a film 12, and an adhesive layer 21 therebetween.

[0054] At least a part of the film 11 is flexible and can be curved. A plurality of pixels are arranged in a matrix on the film 11, and an image can be displayed.

[0055] At least one display element is provided in each pixel provided on the film 11. The pixel may also include a transistor, a wiring, and the like.

[0056] Representatively, an organic EL element can be used as the display element. In addition, various other display elements can be used, such as inorganic EL elements, light-emitting elements such as LED elements, liquid crystal elements, microcapsules, electrophoretic elements, electrowetting elements, electrofluidic elements, electrochromic elements, and MEMS elements.

[0057] Film 11 is not limited to being made of a single film, and may be a laminate of multiple thin sheet-like members. For example, it may be a laminate in which display elements, transistors, wiring, electrodes, etc. constituting pixels and driving circuits are sealed between a pair of films. Here, a configuration including film 11, film 12, and adhesive layer 21 is referred to as display panel 10, but film 11 may have the function of displaying an image by itself.

[0058] Specific examples of the sheet-like member constituting the film 11 include resins such as epoxy resin, aramid resin, acrylic resin, imide resin, and amide-imide resin, and glass having a thickness sufficient to provide flexibility. Alternatively, ester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylonitrile resin, methyl methacrylate resin, polycarbonate (PC), polyethersulfone (PES), amide resins (nylon, aramid, etc.), siloxane resin, cycloolefin resin, styrene resin, urethane resin, vinyl chloride resin, vinylidene chloride resin, propylene resin, polytetrafluoroethylene (PTFE), ABS resin, cellulose nanofiber, etc. may be used.

[0059] At least a portion of film 12 is flexible and can be curved. Film 12 is located on the display surface side of display panel 10, and has a function of protecting the display elements and the like provided on film 11. Film 12 is translucent, and a user can see an image displayed on film 11 through film 12 and adhesive layer 21. The surface of film 12 opposite to film 11 functions as the display surface of display panel 10.

[0060] The film 12 may also function as a touch sensor panel or an optical film. The touch sensor panel may include a sensor element such as a capacitance touch sensor, an optical sensor, or a pressure-sensitive touch sensor. Examples of the optical film include a circular polarizing plate and an anti-reflection film (including an AR (Anti-Reflection) film and an AG (Anti-Glare) film).

[0061] It is preferable to use a sheet-like member having at least one of urethane resin, acrylic resin, silicone resin, fluororesin, olefin resin, vinyl resin, styrene resin, amide resin, ester resin, and epoxy resin as the film 12. In particular, urethane resin has a relatively high dielectric constant, and can increase sensitivity when a capacitance-type touch sensor is applied. In addition, it is preferable because it can impart high slipperiness and self-repairing properties to the surface.

[0062] In particular, it is preferable to use an organic resin having self-repairing properties as the material located on the outermost surface of the film 12, since it is possible to prevent surface scattering due to scratches and the like and maintain display quality. In addition, by using a resin having water repellency or oil repellency as the organic resin, or by performing a surface treatment to impart water repellency or oil repellency to the outermost surface of the film 12, it is possible to prevent dirt such as fingerprints from adhering to the surface of the film 12. In other words, it is possible to impart antifouling properties to the film 12. As the material having self-repairing properties, for example, in addition to the above-mentioned urethane resin, a material containing polyrotaxane, cyclodextrin, polyphenylene ether, etc. can be used. In this case, it is more preferable that the film 12 is configured by laminating the organic resin having self-repairing properties on a sheet-like member made of one or more of the above-mentioned urethane resin, acrylic resin, and silicone resin.

[0063] In order to improve the slipperiness of the film 12, it is preferable to carry out coating, surface treatment, or attaching a film with high slipperiness.

[0064] The adhesive layer 21 is located between the film 11 and the film 12 and has the function of adhering them. The adhesive layer 21 is preferably made of a material that transmits visible light and exhibits viscoelasticity. In particular, the adhesive layer 21 is preferably made of a material that is more viscous than elastic.

[0065] The adhesive layer 21 has a property of being deformed when an external force is applied, but maintaining its shape by stress relaxation. The relaxation time required for stress relaxation of the adhesive layer 21 is preferably 0.01 seconds or more and 10 seconds or less, and more preferably 0.05 seconds or more and 5 seconds or less. A material with a relaxation time of less than 0.01 seconds becomes close to a fluid, and therefore the function of bonding the film 11 and the film 12 is reduced. On the other hand, if the relaxation time is longer than 10 seconds, the adhesive layer 21 itself becomes difficult to bend, since it becomes close to an elastic body. Furthermore, as described later, when the display panel 10 is curved, the neutral plane between the film 11 and the film 12 shifts toward the adhesive layer 21, and the stress applied to the film 11 and the film 12 increases.

[0066] It is preferable to use a viscoelastic material with a relatively low viscosity as the adhesive layer 21. Also, a viscoelastic material with a low elastic modulus can be used. Specific examples include rubber-like materials containing silicone, acrylic resin, urethane resin, etc., and gel-like materials. In particular, it is preferable to use silicone gel, silicone gel containing low molecular weight siloxane, acrylic gel, and urethane gel-like materials.

[0067] For comparison, Fig. 2A will explain a display panel 10R in which films 11 and 12 are bonded together with a highly rigid adhesive 21R. In Fig. 2A, the neutral plane C1 of film 11, the neutral plane C2 of film 12, and the neutral plane C0 of the entire display panel 10R are each indicated by a dashed dotted line. The neutral plane C0 is located inside the adhesive 21R. In the display panel 10R, films 11 and 12 are bonded together with a highly rigid adhesive 21R, and the display panel 10R has a configuration in which the bending modulus is higher than the tensile modulus.

[0068] Fig. 2B shows a schematic cross-sectional view of display panel 10R when it is curved so that the display surface becomes convex. Since neutral surface C0 of display panel 10R is located inside adhesive 21R, in order to curve display panel 10R, film 11 needs to shrink and film 12 needs to expand, as shown by the dashed arrows in Fig. 2B. Fig. 2C shows the case where display panel 10R is curved so that the display surface becomes concave. In this case, film 11 needs to expand and film 12 needs to shrink.

[0069] 2A, in order to prevent damage to the films 11 and 12, it is necessary to form the adhesive 21R as thin as possible and to bring the film 11 and the neutral plane C0, and the film 12 and the neutral plane C0 as close as possible to each other. Therefore, it is difficult to make the adhesive 21R thick, and it is difficult to increase the mechanical strength of the display panel 10R itself.

[0070] 1A shows a neutral surface C1 of film 11, a neutral surface C2 of film 12, and a neutral surface C0 of display panel 10. Neutral surface C1 is located within film 11, neutral surface C2 is located within film 12, and neutral surface C0 is located within adhesive layer 21.

[0071] FIG. 1B shows the display panel 10 when curved so that the display surface is convex.

[0072] 1B, adhesive layer 21 deforms such that it expands closer to film 11 and contracts closer to film 12, with the vicinity of neutral plane C0 as the boundary. As a result, film 11 can be curved without contracting, and film 12 can be curved without stretching.

[0073] In this way, the display panel 10 can be curved with a small force by deformation of the adhesive layer 21, so it is possible to increase the thickness of the adhesive layer 21. By increasing the thickness of the adhesive layer 21, the impact resistance of the display panel 10 can be increased, and the reliability can be improved. The thickness of the adhesive layer 21 can be, for example, 1 μm to 10 mm, preferably 5 μm to 5 mm, more preferably 10 μm to 3 mm, and even more preferably 20 μm to 2 mm.

[0074] 1C shows a state in which display panel 10 is curved so that the display surface is concave. At this time, adhesive layer 21 deforms so that it shrinks closer to film 11 and expands closer to film 12, with the vicinity of neutral plane C0 as the boundary.

[0075] Moreover, when attention is paid to the shape of the display panel 10 in FIG. 1B, the shape is such that the end face of film 11 is positioned outward from the straight line connecting the end face of film 12 positioned outward and the center O of curvature. In other words, in the vicinity of the end face of film 12, when viewed from a direction perpendicular to the surface of film 12, the end face of film 11 is shaped to protrude outward from the end face of film 12. In this way, when the display panel 10 is gradually curved from a flat state, the end face of film 11 and the end face of film 12 are shifted so as to move relatively apart, and the display panel 10 is deformed. This is because the display panel 10 is curved without expansion and contraction of films 11 and 12.

[0076] On the other hand, in the case of the display panel 10R shown in FIG. 2B, the adhesive 21R has rigidity, so that the inner film 11 shrinks and the outer film 12 stretches, and no misalignment occurs at these ends when the display panel 10R is curved.

[0077] Although an example of the display panel 10 here has a pair of films and one adhesive layer 21, the present invention is not limited to this, and the display panel 10 may also have a configuration in which three or more films are stacked with adhesive layers 21 interposed therebetween.

[0078] Fig. 3A shows an example of a display panel 10A having a film 13 between films 11 and 12. An adhesive layer 21a is provided between films 11 and 13, and an adhesive layer 21b is provided between films 13 and 12. In Fig. 3A, a neutral surface C3 of film 13 is indicated by a dashed line.

[0079] The adhesive layer 21a and the adhesive layer 21b may be made of the same material as the adhesive layer 21. The film 13 may be made of the same light-transmitting material as the film 12. For example, the film 13 may be made of a film having at least one of a function as a touch sensor panel and a function as an optical film, and the film 12 may be made of a film having at least one of high slipperiness and self-repairing properties.

[0080] FIG. 3B shows a state in which the display panel 10A is curved so that the display surface is convex. As with the display panel 10, the adhesive layer 21a and the adhesive layer 21b are deformed, and the display panel 10A can be curved without any of the films 11, 12, and 13 expanding or contracting. The display panel 10A in FIG. 3B has a shape in which the end face of the film 13 is located outside the straight line connecting the end face of the film 12 located outside and the center of curvature O, and the end face of the film 11 is located further outside. In other words, in the vicinity of the end face of the film 12, when viewed from a direction perpendicular to the surface of the film 12, the end face of the film 13 is shifted outward relative to the end face of the film 12, and the end face of the film 11 is also shifted outward relative to the end face of the film 13. In this way, when the film located on the outermost side is used as a reference, the closer the film is to the center of curvature O, the greater the shift in the end face.

[0081] [Example of application] The display panel of one embodiment of the present invention can be applied to a display portion of an electronic device. In this case, the display panel can be incorporated into the electronic device in a form in which the display surface is flat without being curved, or in a form in which the display panel is fixed in a partially curved state. In particular, the display panel of one embodiment of the present invention can be suitably incorporated into a foldable device such as an electronic device that can be folded in two so that the display surface faces inward or outward, or an electronic device that can fold the display panel into three or more parts.

[0082] [Application example 1] Fig. 4A shows an example of a case where the display panel 10 is used without being curved. Fig. 4A shows the display panel 10, the support 31, the FPC 26, and the connector 27. Fig. 4A also shows, with dashed arrows, a schematic diagram of the emission direction of light when the display panel 10 displays an image.

[0083] The support 31 is a member that supports the display panel 10. The support 31 is located on the opposite side to the display surface side of the display panel 10, and supports the film 11. The support 31 may be a part of the housing of the electronic device, or a member provided inside the housing of the electronic device.

[0084] The FPC 26 is electrically connected to an external circuit and has a function of transmitting a power supply potential and various signals from the circuit to the display panel 10. The FPC 26 is electrically connected to terminals of the film 11 by connectors 27. As the connectors 27, for example, an anisotropic conductive film can be used.

[0085] In the display panel 10 according to one embodiment of the present invention, the upper surface of the film 11 is protected by a viscoelastic adhesive layer 21. Therefore, the display panel 10 has excellent mechanical strength such as impact resistance, and can be suitably used in applications where the display panel 10 does not need to be curved, as shown in FIG.

[0086] [Application example 2] 4B and 4C show examples in which a curved support 31 is used. Fig. 4B shows an example in which the display panel 10 is supported on the convex side of the support 31. Fig. 4C shows an example in which the display panel 10 is supported on the concave side of the support 31.

[0087] 4B, display panel 10 is curved so that the display surface is convex. Also, focusing on the vicinity of the end of film 12, adhesive layer 21 is deformed so that the end surface is stretched, and the end surface of film 11 protrudes outward beyond the end surface of film 12 when viewed from the display surface side.

[0088] 4C, the display surface of display panel 10 is curved to be concave. Focusing on the vicinity of the end of film 12, adhesive layer 21 is deformed so that the end surface is stretched, and the end surface of film 12 protrudes outward beyond the end surface of film 11 when viewed from the display surface side.

[0089] In this way, when the display panel 10 is fixed to the support 31 in a curved state, the restoring force of the display panel 10 to a flat state is extremely small, so that problems such as the display panel 10 peeling off from the support 31 can be suppressed.

[0090] [Application example 3] 4D and 4E show an example in which the display panel 10 has a portion that is curved by 180 degrees and a flat portion.

[0091] 4D, images can be displayed in opposite directions across support 31. Furthermore, on the side surface portion of support 31 having a curved surface, an image can be displayed along the curved surface.

[0092] 4E, the display panel 10 is supported by two supports, support 31a and support 31b. Support 31a mainly supports the display portion of the display panel 10, and support 31b mainly supports the connection portion between the display panel 10 and the FPC 26. By folding back the display panel 10 in this way so that the connection portion connecting the FPC 26 is located on the side opposite the display surface side, it is possible to reduce the space required to incorporate the display panel 10 into an electronic device.

[0093] 4E, FPC 26 has a bifurcated shape, one part of which is electrically connected to film 11 via connector 27a, and the other part of which is electrically connected to film 12 via connector 27b. This configuration is applicable, for example, to the case where film 12 functions as a touch sensor panel or the like.

[0094] The support 31b may be a protective member for preventing the display panel 10 from being damaged when, for example, the FPC 26 is pressure-bonded to the display panel 10. Furthermore, as shown in Fig. 4E, the support 31b is fixed to the support 31a by the adhesive layer 32, thereby preventing physical stress from being applied to the display panel 10 during the work of incorporating the FPC 26 into an electronic device.

[0095] [Application Example 4] 5A to 5D show an example in which the display surface side of the display panel 10 is supported by a support 33. Fig. 5A and Fig. 5C are perspective views, and Fig. 5B and Fig. 5D are cross-sectional views. Note that FPCs and the like are omitted in Fig. 5A to Fig. 5D. Also, in Fig. 5A and Fig. 5C, the support 33 is indicated by a dashed line.

[0096] 5A to 5D, a material that transmits at least visible light can be used for the support 33. The support 33 can also be called a protective cover. It is preferable to use, for example, plastic or glass (preferably tempered glass) as the support 33, since this can provide suitable protection for the display panel 10.

[0097] 5A and 5B, the surface of the support 33 facing the display panel 10 has a flat portion and a curved portion adjacent to the flat portion. The display panel 10 is provided along the surface. That is, the display panel 10 has a pair of curved portions and a flat portion sandwiched between the curved portions. Each of the pair of curved portions is curved so that the display surface is convex.

[0098] 5C and 5D, the curved portion of the display panel 10 is folded back 180 degrees, which allows images to be displayed not only in the front direction but also on both sides.

[0099] [Application example 5] 6A and 6B show a configuration in which the display panel 10 can be folded into three. Fig. 6A shows the display panel 10 folded into three, and Fig. 6B shows the display panel 10 in a flattened state.

[0100] The configuration shown in FIGS. 6A and 6B includes a display panel 10, a support 34a, a support 34b, a support 34c, a connecting portion 35, a connecting portion 36, and the like.

[0101] The display panel 10 has a portion supported by the support 34a, a portion supported by the support 34b, and a portion supported by the support 34c. Each portion is supported so that the display surface is flat.

[0102] The connecting portion 35 connects the support 34b and the support 34c. The connecting portion 35 has a mechanism for connecting the support 34b and the support 34c so that the display surface of the display panel 10 can be reversibly deformed between a flat state and a curved state in which the display surface side faces outward.

[0103] The connecting portion 36 connects the support 34a and the support 34b. The connecting portion 36 has a mechanism for connecting the support 34a and the support 34b so that the display surface of the display panel 10 can be reversibly deformed between a flat state and a curved state in which the display surface side faces inward.

[0104] Such connecting portions 35 and 36 allow display panel 10 to be reversibly transformed between a state in which display panel 10 is folded in three and a state in which display panel 10 is generally flat, as shown in FIG. 6A.

[0105] 6A and 6B show an example in which the connecting portion 35 and the connecting portion 36 have a structure in which a plurality of pillars are connected. The display panel 10 is supported on one surface of the pillars. It is preferable that two adjacent pillars are provided in contact with each other so that no gap is generated between the surfaces supporting the display panel 10. The pillars of the connecting portion 35 have a substantially trapezoidal cross-sectional shape. On the other hand, the pillars of the connecting portion 36 have a substantially rectangular cross-sectional shape.

[0106] Furthermore, the connecting portion 35 and the connecting portion 36 may be configured to operate synchronously or independently. The configuration of the connecting portion 35 and the connecting portion 36 is not limited to the configuration exemplified in Fig. 6A and Fig. 6B, and may be in various forms. In particular, it is preferable to have a mechanism that can bend the display panel 10 without expanding or contracting it.

[0107] 6A and 6B also show a connector 27a and an FPC 26a that are electrically connected to the film 11, and a connector 27b and an FPC 26b that are electrically connected to the film 12. As shown in FIG.

[0108] [Application Example 6] 7A and 7B show an example having two mechanisms for curving the display panel 10 so that the display surface of the display panel 10 faces outward. The configuration shown in Fig. 7A and 7B includes the display panel 10, support 34d, support 34e, support 34f, connecting portion 35a, and connecting portion 35b.

[0109] The connecting portion 35a connects the support 34f and the support 34e. The connecting portion 35b connects the support 34e and the support 34d. The configuration of the connecting portion 35a and the connecting portion 35b can be the same as that of the connecting portion 35 illustrated in the above-mentioned application example 5.

[0110] [Application Example 7] The configurations shown in FIGS. 8A and 8B are examples of configurations in which the display panel 10 can be folded in two.

[0111] Fig. 8A shows an example in which the display panel 10 is folded in two so that the display surface faces outward. The configuration shown in Fig. 8A includes the display panel 10, support 34g, support 34h, and connecting portion 35. Connecting portion 35 connects support 34g and support 34h.

[0112] Fig. 8B shows an example in which the display panel 10 is folded in two so that the display surface faces inward. The configuration shown in Fig. 8B includes the display panel 10, support 34j, support 34k, and connecting portion 36. Connecting portion 36 connects support 34j and support 34k.

[0113] The configurations exemplified in Application Examples 5 to 7 have excellent portability and portability when the display panel 10 is folded, and have excellent viewability when the display panel 10 is opened. The display panel of one embodiment of the present invention has high reliability against repeated deformation, and therefore can be suitably used in such foldable devices.

[0114] The above is a description of the application example.

[0115] This embodiment mode can be implemented by appropriately combining at least a part of it with other embodiment modes described in this specification.

[0116] (Embodiment 2) In this embodiment, a structure example of a display panel that can be used for a display device of one embodiment of the present invention will be described.

[0117] [Configuration example] 9A is a schematic top view of a display device 700. The display device 700 includes a flexible substrate 762. The substrate 762 is provided with a display portion 702, a pair of circuit portions 763, a circuit portion 764, wiring 704, and a connection terminal 703a and a connection terminal 703b.

[0118] The circuit portion 763 and the circuit portion 764 have a function of driving the display portion 702. Two circuit portions 763 are provided on either side of the display portion 702. The circuit portion 764 is provided between the display portion 702 and the wiring 704. The circuit portion 763 has a function as, for example, a gate driver, and the circuit portion 764 has a function as, for example, a source driver or a part thereof. For example, the circuit portion 764 may include a buffer circuit or a demultiplexer circuit.

[0119] A light-emitting element or the like can be used as the display element provided in the display unit 702. Examples of the light-emitting element include self-luminous light-emitting elements such as LEDs (Light Emitting Diodes), OLEDs (Organic LEDs), QLEDs (Quantum-dot LEDs), and semiconductor lasers. In addition, liquid crystal elements such as transmissive liquid crystal elements, reflective liquid crystal elements, and semi-transmissive liquid crystal elements can also be used as the display element. In addition, a shutter-type or optical interference-type MEMS (Micro Electro Mechanical Systems) element, or a display element using a microcapsule type, an electrophoresis type, an electrowetting type, or an electronic liquid powder (registered trademark) type can also be used. In particular, it is preferable to use an organic EL element as the display element.

[0120] The substrate 762 has a top surface shape in which a portion where the wiring 704, the connection terminal 703a, and the connection terminal 703b are provided protrudes from another portion (a portion where the display portion 702 is provided). In other words, the width of the portion (also called a protruding portion) of the substrate 762 is smaller than the width of the portion where the display portion 702 is provided.

[0121] The protruding portion of the substrate 762 has a region (curved portion 761a) that can be curved in a region overlapping with the wiring 704. The substrate 762 also has a pair of regions (curved portions 761b) that can be curved in a region where the display unit 702 is provided. As shown in FIG 9A, by having a part of the substrate 762 have a protruding shape, the curving direction of the curved portion 761a and the curving direction of the curved portion 761b can be set to intersect.

[0122] The connection terminal 703a functions as a terminal to which an FPC (Flexible Printed Circuit) is connected, and the connection terminal 703b functions as a terminal to which an IC is connected.

[0123] 9B and 9C are perspective views of the display device 700 when the substrate 762 is bent on the side opposite the display surface side at the curved portions 761a and 761b. Fig. 9B is a perspective view including the display surface side, and Fig. 9C is a perspective view including the side opposite the display surface side. Fig. 9C also clearly shows the FPC 706 connected to the connection terminal 703a and the IC 707 connected to the connection terminal 703b.

[0124] 9B, by curving both sides of the display unit 702, curved display units can be provided on both sides of the electronic device when the display device 700 is incorporated into the electronic device. This makes it possible to realize an electronic device with high functionality.

[0125] 9B and 9C, a part of the substrate 762 can be folded back to the opposite side to the display surface side by the curved portion 761a. Specifically, the protruding portion of the substrate 762 can be folded back so that the wiring 704 is on the outside. This allows the connection terminals 703a and 703b to be disposed on the opposite side to the display surface side, and further allows the FPC 706 to be disposed on the opposite side to the display surface side. This makes it possible to reduce the area of ​​the non-display portion when the display device 700 is incorporated into an electronic device.

[0126] The substrate 762 is provided with a notch 765. The notch 765 is a portion where, for example, a camera lens, various sensors such as an optical sensor, a lighting device, or a design of the electronic device can be arranged. By cutting out a part of the display unit 702, an electronic device with a higher design quality can be realized. This also increases the occupancy rate of the screen relative to the surface of the housing.

[0127] [Cross-section example] An example of a cross-sectional configuration of a display device will be described below.

[0128] [Configuration Example 1] Fig. 10 is a schematic cross-sectional view of a display device 700. Fig. 10 shows a cross section including a display portion 702, a circuit portion 763, a curved portion 761a, and a connection terminal 703a of the display device 700 shown in Fig. 9A. The display portion 702 is provided with a transistor 750 and a capacitor 790. The circuit portion 763 is provided with a transistor 752.

[0129] The transistor 750 and the transistor 752 are transistors in which an oxide semiconductor is used for a semiconductor layer in which a channel is formed. Note that the present invention is not limited to this, and a transistor in which silicon (amorphous silicon, polycrystalline silicon, or single crystal silicon) or an organic semiconductor is used for the semiconductor layer can also be used.

[0130] The transistor used in this embodiment has an oxide semiconductor film that is highly purified and in which formation of oxygen vacancies is suppressed. The off-state current of the transistor can be significantly reduced. Therefore, a pixel including such a transistor can hold an electric signal such as an image signal for a long time and can set a long interval for writing an image signal or the like. Thus, the frequency of a refresh operation can be reduced, leading to reduced power consumption.

[0131] In addition, the transistor used in this embodiment mode can achieve a relatively high field-effect mobility and thus can be driven at high speed. For example, by using such a transistor capable of high speed driving in a display device, a switching transistor of a pixel and a driver transistor used in a circuit portion can be formed over the same substrate. That is, a configuration without using a driver circuit formed of a silicon wafer or the like is also possible, and the number of components of the display device can be reduced. In addition, by using a transistor capable of high speed driving in a pixel, a high-quality image can be provided.

[0132] The capacitor 790 has a lower electrode formed by processing the same film as the first gate electrode of the transistor 750, and an upper electrode formed by processing the same metal oxide film as the semiconductor layer. The upper electrode has a low resistance like the source and drain regions of the transistor 750. A part of an insulating film functioning as the first gate insulating layer of the transistor 750 is provided between the lower electrode and the upper electrode. That is, the capacitor 790 has a stacked structure in which an insulating film functioning as a dielectric film is sandwiched between a pair of electrodes. A wiring obtained by processing the same film as the source and drain electrodes of the transistor 750 is connected to the upper electrode.

[0133] An insulating layer 770 functioning as a planarization film is provided over the transistor 750, the transistor 752, and the capacitor 790.

[0134] The transistor 750 in the display portion 702 and the transistor 752 in the circuit portion 763 may have different structures. For example, a top-gate transistor may be used for one of them, and a bottom-gate transistor may be used for the other. Note that the circuit portion 764 is similar to the circuit portion 763.

[0135] The connection terminal 703a has a part of the wiring 704. As shown in Fig. 10, the connection terminal 703a preferably has a laminated structure in which a plurality of conductive films are laminated, because the electrical conductivity and mechanical strength of the connection terminal 703a are increased. The connection terminal 703a is electrically connected to the FPC 706 via a connection layer 780. For example, an anisotropic conductive material or the like can be used as the connection layer 780.

[0136] The display device 700 includes a substrate 762 and a substrate 740 each functioning as a support substrate. As the substrate 762 and the substrate 740, for example, a flexible substrate such as a glass substrate or a plastic substrate can be used.

[0137] 10, the laminated structure from substrate 762 to substrate 740 is film 721. Film 722 is attached onto substrate 740 via adhesive layer 720. Adhesive layer 720, film 721, and film 722 correspond to adhesive layer 21, film 11, and film 12 in the first embodiment, respectively.

[0138] The transistor 750, the transistor 752, the capacitor 790, and the like are provided over an insulating layer 744. The substrate 762 and the insulating layer 744 are attached to each other with an adhesive layer 742.

[0139] The display device 700 also includes a light-emitting element 782, a colored layer 736, a light-shielding layer 738, and the like.

[0140] The light-emitting element 782 includes a conductive layer 772, an EL layer 786, and a conductive layer 788. The conductive layer 772 is electrically connected to a source electrode or a drain electrode of the transistor 750. The conductive layer 772 is provided over the insulating layer 770 and functions as a pixel electrode. In addition, an insulating layer 730 is provided to cover an end portion of the conductive layer 772, and an EL layer 786 and a conductive layer 788 are stacked over the insulating layer 730 and the conductive layer 772.

[0141] The conductive layer 772 can be formed using a material that is reflective to visible light. For example, a material containing aluminum, silver, or the like can be used. The conductive layer 788 can be formed using a material that transmits visible light. For example, an oxide material containing indium, zinc, tin, or the like can be used. Therefore, the light-emitting element 782 is a top-emission light-emitting element that emits light to the side opposite to the surface where the light is formed (the side of the substrate 740).

[0142] The EL layer 786 may include organic compounds or inorganic compounds such as quantum dots, etc. The EL layer 786 includes a light-emitting material that emits light when a current is passed through it.

[0143] Examples of luminescent materials include fluorescent materials, phosphorescent materials, thermally activated delayed fluorescence (TADF) materials, inorganic compounds (quantum dot materials, etc.), etc. Examples of materials that can be used for quantum dots include colloidal quantum dot materials, alloy-type quantum dot materials, core-shell type quantum dot materials, core-type quantum dot materials, etc.

[0144] The light-shielding layer 738 and the colored layer 736 are provided on one surface of the insulating layer 746. The colored layer 736 is provided at a position overlapping with the light-emitting element 782. The light-shielding layer 738 is provided in a region of the display portion 702 that does not overlap with the light-emitting element 782. The light-shielding layer 738 may also be provided to overlap with the circuit portion 763 and the like.

[0145] The substrate 740 is bonded to the other surface of the insulating layer 746 by an adhesive layer 747. The substrate 740 and the substrate 762 are bonded to each other by a sealing layer 732.

[0146] Here, a light-emitting material that emits white light is used as the EL layer 786 of the light-emitting element 782. The white light emitted by the light-emitting element 782 is colored by the coloring layer 736 and emitted to the outside. The EL layer 786 is provided across pixels that exhibit different colors. By arranging pixels, each of which is provided with a coloring layer 736 that transmits any of red (R), green (G), or blue (B), in a matrix form in the display unit 702, the display device 700 can perform full-color display.

[0147] A conductive film having transparency and reflectivity may be used as the conductive layer 788. In this case, a microresonator (microcavity) structure may be realized between the conductive layer 772 and the conductive layer 788, and a configuration may be adopted in which light of a specific wavelength is intensified and emitted. In this case, an optical adjustment layer for adjusting the optical distance may be disposed between the conductive layer 772 and the conductive layer 788, and the thickness of the optical adjustment layer may be made different between pixels of different colors, thereby increasing the color purity of the light emitted from each pixel.

[0148] When the EL layer 786 is formed in an island shape for each pixel or in a stripe shape for each pixel row, that is, when the EL layer 786 is formed by coloring, the colored layer 736 and the optical adjustment layer described above may not be provided.

[0149] Here, an inorganic insulating film functioning as a barrier film with low moisture permeability is preferably used for each of the insulating layers 744 and 746. By sandwiching the light-emitting element 782, the transistor 750, and the like between the insulating layers 744 and 746, deterioration of the light-emitting element 782, the transistor 750, and the like can be suppressed, and a highly reliable display device can be realized.

[0150] [Configuration Example 2] Fig. 11 shows a cross-sectional view of display device 700 having a configuration partially different from that of Fig. 10. Fig. 11 also clearly shows a configuration in which part of display device 700 is curved at curved portion 761a and folded back to the side opposite the display surface side.

[0151] The display device 700 shown in Fig. 11 includes a resin layer 743 between the adhesive layer 742 and the insulating layer 744 shown in Fig. 10. Also, a protective layer 749 is provided instead of the substrate 740.

[0152] The resin layer 743 is a layer containing an organic resin such as polyimide or acrylic. The insulating layer 744 contains an inorganic insulating film such as silicon oxide, silicon oxynitride, or silicon nitride. The resin layer 743 and the substrate 762 are attached to each other by an adhesive layer 742. The resin layer 743 is preferably thinner than the substrate 762.

[0153] The protective layer 749 is attached to the sealing layer 732. A glass substrate, a resin film, or the like can be used as the protective layer 749. In addition, as the protective layer 749, an optical member such as a polarizing plate (including a circular polarizing plate) or a scattering plate, an input device such as a touch sensor panel, or a configuration in which two or more of these are laminated may be used.

[0154] Here, the laminated structure from the substrate 762 to the protective layer 749 can be a film 721. The film 722 is attached to the protective layer 749 via an adhesive layer 720.

[0155] In addition, the EL layer 786 of the light-emitting element 782 is provided in an island shape over the insulating layer 730 and the conductive layer 772. By forming the EL layer 786 so that each subpixel has a different light emission color, color display can be realized without using the coloring layer 736.

[0156] A protective layer 741 is provided to cover the light-emitting element 782. The protective layer 741 has a function of preventing impurities such as water from diffusing into the light-emitting element 782. The protective layer 741 has a layered structure in which an insulating layer 741a, an insulating layer 741b, and an insulating layer 741c are layered in this order from the conductive layer 788 side. In this case, it is preferable to use an inorganic insulating film having a high barrier property against impurities such as water for the insulating layer 741a and the insulating layer 741c, and an organic insulating film functioning as a planarization film for the insulating layer 741b. It is also preferable that the protective layer 741 is provided so as to extend to the circuit portion 763 and the like.

[0157] In addition, the organic insulating film covering the transistor 750, the transistor 752, and the like is preferably formed in an island shape inside the sealing layer 732. In other words, the end of the organic insulating film is preferably located inside the sealing layer 732 or in a region overlapping with the end of the sealing layer 732. FIG. 11 shows an example in which the insulating layer 770, the insulating layer 730, and the insulating layer 741b are processed into an island shape. For example, in a portion overlapping with the sealing layer 732, the insulating layer 741c and the insulating layer 741a are provided in contact with each other. In this way, the surface of the organic insulating film covering the transistor 750 and the transistor 752 is not exposed outside the sealing layer 732, so that water or hydrogen can be suitably prevented from diffusing from the outside to the transistor 750 and the transistor 752 through the organic insulating film. This suppresses fluctuations in the electrical characteristics of the transistors, and a display device with extremely high reliability can be realized.

[0158] 11, curved portion 761a has a portion where inorganic insulating films such as insulating layer 744 are not provided, in addition to substrate 762 and adhesive layer 742. Curved portion 761a has a configuration in which insulating layer 770 containing an organic material covers wiring 704 to prevent wiring 704 from being exposed. In the configuration shown in FIG. 11, curved portion 761a has a layered structure in which resin layer 743, wiring 704, and insulating layer 770 are layered.

[0159] By providing as little inorganic insulating film as possible in the curved portion 761a and stacking only a conductive layer containing a metal or alloy and a layer containing an organic material, it is possible to prevent cracks from occurring when the display device 700 is bent. Also, by not providing a substrate 762 in the curved portion 761a, a part of the display device 700 can be bent with an extremely small radius of curvature.

[0160] In addition, in a region overlapping with connection terminal 703a, support 725 is attached to resin layer 743 via adhesive layer 748. Support 725 can be made of a material having higher rigidity than substrate 762, etc. Alternatively, support 725 may be a part of a housing of an electronic device, or a part of a member disposed inside the electronic device.

[0161] 11, a conductive layer 761 is provided over the protective layer 741. The conductive layer 761 can be used as a wiring or an electrode.

[0162] Furthermore, when a touch sensor is provided overlapping the display device 700, the conductive layer 761 can function as an electrostatic shielding film for preventing electrical noise generated when a pixel is driven from being transmitted to the touch sensor. In this case, a predetermined constant potential may be applied to the conductive layer 761.

[0163] Alternatively, the conductive layer 761 can be used as, for example, an electrode of a touch sensor. This allows the display device 700 to function as a touch panel. For example, the conductive layer 761 can be used as an electrode or wiring of a capacitive touch sensor. In this case, the conductive layer 761 can be used as a wiring or electrode to which a detection circuit is connected or a wiring or electrode to which a sensor signal is input. In this manner, by forming a touch sensor over the light-emitting element 782, the number of components can be reduced, and the manufacturing costs of electronic devices and the like can be reduced.

[0164] The conductive layer 761 is preferably provided in a portion that does not overlap with the light-emitting element 782. For example, the conductive layer 761 can be provided in a portion that overlaps with the insulating layer 730. As a result, there is no need to use a transparent conductive film with relatively low conductivity as the conductive layer 761, and a metal or alloy with high conductivity can be used, which can improve the sensitivity of the sensor.

[0165] Note that the type of the touch sensor that can be configured using the conductive layer 761 is not limited to the capacitance type, and various types such as a resistive film type, a surface acoustic wave type, an infrared type, an optical type, and a pressure sensitive type can be used. Alternatively, two or more of these types may be used in combination.

[0166] [About the components] Components such as transistors that can be applied to a display device will be described below.

[0167] [Transistor] The transistor includes a conductive layer functioning as a gate electrode, a semiconductor layer, a conductive layer functioning as a source electrode, a conductive layer functioning as a drain electrode, and an insulating layer functioning as a gate insulating layer.

[0168] Note that the structure of a transistor included in a display device of one embodiment of the present invention is not particularly limited. For example, a planar transistor, a staggered transistor, or an inverted staggered transistor may be used. In addition, the transistor may have either a top-gate type or a bottom-gate type structure. Alternatively, gate electrodes may be provided above and below a channel.

[0169] The crystallinity of a semiconductor material used in a transistor is not particularly limited, and any of an amorphous semiconductor, a single crystal semiconductor, and a semiconductor having crystallinity other than a single crystal (a microcrystalline semiconductor, a polycrystalline semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a single crystal semiconductor or a semiconductor having crystallinity is preferable because it can suppress deterioration of transistor characteristics.

[0170] In particular, a transistor using a metal oxide film for a semiconductor layer in which a channel is formed will be described below.

[0171] As a semiconductor material for a transistor, a metal oxide having an energy gap of 2 eV or more, preferably 2.5 eV or more, more preferably 3 eV or more can be used. A representative example is a metal oxide containing indium, such as CAC-OS described later.

[0172] A transistor using a metal oxide which has a wider band gap and a lower carrier density than silicon can hold charge accumulated in a capacitor connected in series with the transistor for a long period of time owing to its low off-state current.

[0173] The semiconductor layer may be, for example, a film represented by an In-M-Zn system oxide containing indium, zinc, and M (M is a metal such as aluminum, titanium, gallium, germanium, yttrium, zirconium, lanthanum, cerium, tin, neodymium, or hafnium).

[0174] When the metal oxide constituting the semiconductor layer is an In-M-Zn oxide, the atomic ratio of the metal elements of the sputtering target used to form the In-M-Zn oxide preferably satisfies In≧M and Zn≧M. As the atomic ratio of the metal elements of such a sputtering target, In:M:Zn=1:1:1, In:M:Zn=1:1:1.2, In:M:Zn=3:1:2, In:M:Zn=4:2:3, In:M:Zn=4:2:4.1, In:M:Zn=5:1:3, In:M:Zn=5:1:6, In:M:Zn=5:1:7, In:M:Zn=5:1:8, In:M:Zn=10:1:3, In:M:Zn=5:3:4, etc. are preferable. The atomic ratio of the semiconductor layer to be formed includes a variation of ±40% of the atomic ratio of the metal elements contained in the above sputtering target.

[0175] The semiconductor layer is a metal oxide film with a low carrier density. For example, the semiconductor layer is a metal oxide film with a carrier density of 1×10 17 / cm 3 Less than or equal to 1×10 15 / cm 3Less than 1×10, more preferably 13 / cm 3 Less than or equal to 1×10 11 / cm 3 Less than 1×10, more preferably 10 / cm 3 Less than 1 x 10 -9 / cm 3 A metal oxide having a carrier density of 1000 or more can be used. Such a metal oxide is called a high-purity intrinsic or substantially high-purity intrinsic metal oxide. The oxide semiconductor has a low density of defect states and is therefore a metal oxide having stable characteristics.

[0176] Note that the present invention is not limited to these, and an oxide semiconductor having an appropriate composition may be used depending on the semiconductor characteristics and electrical characteristics (field-effect mobility, threshold voltage, etc.) of a transistor that is required. In order to obtain the semiconductor characteristics of a transistor that is required, it is preferable to set the carrier density, impurity concentration, defect density, atomic ratio of a metal element to oxygen, interatomic distance, density, and the like of the semiconductor layer to be appropriate.

[0177] When silicon or carbon, which is one of the group 14 elements, is contained in the metal oxide constituting the semiconductor layer, oxygen vacancies increase in the semiconductor layer, causing it to become n-type. For this reason, the concentration of silicon or carbon in the semiconductor layer (concentration obtained by secondary ion mass spectrometry) is set to 2×10 18 atoms / cm 3 Less than or equal to 2 x 10 17 atoms / cm 3 The following applies.

[0178] In addition, when an alkali metal or an alkaline earth metal is bonded to a metal oxide, carriers may be generated, which may increase the off-state current of a transistor. For this reason, the concentration of an alkali metal or an alkaline earth metal in a semiconductor layer obtained by secondary ion mass spectrometry is set to 1×10 18 atoms / cm 3 Less than or equal to 2 x 10 16 atoms / cm 3 To the following:

[0179] In addition, when nitrogen is contained in the metal oxide that constitutes the semiconductor layer, electrons that act as carriers are generated, the carrier density increases, and the transistor tends to become n-type. As a result, transistors that use metal oxides that contain nitrogen tend to have normally-on characteristics. For this reason, the nitrogen concentration in the semiconductor layer obtained by secondary ion mass spectrometry is 5×10 18 atoms / cm 3 It is preferable to do the following:

[0180] Oxide semiconductors (metal oxides) are classified into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors, such as c-axis aligned crystalline oxide semiconductors (CAAC-OS), polycrystalline oxide semiconductors, nanocrystalline oxide semiconductors (nc-OS), amorphous-like oxide semiconductors (a-like OS), and amorphous oxide semiconductors.

[0181] CAAC-OS has a c-axis orientation and a distorted crystal structure in which multiple nanocrystals are connected in the ab-plane direction. The distortion refers to a portion where the lattice orientation changes between a region with a uniform lattice arrangement and a region with a different uniform lattice arrangement in the region where multiple nanocrystals are connected.

[0182] Nanocrystals are basically hexagonal, but may be non-regular hexagonal. In addition, the lattice arrangement of the distortion may be pentagonal, heptagonal, or the like. In the CAAC-OS, it is difficult to confirm clear grain boundaries even in the vicinity of the distortion. That is, it is found that the formation of grain boundaries is suppressed by the distortion of the lattice arrangement. This is because the CAAC-OS can tolerate distortion because the arrangement of oxygen atoms in the ab-plane direction is not dense, and the bond distance between atoms changes due to the substitution of metal elements. A crystal structure in which clear grain boundaries are confirmed is called a polycrystal. The grain boundaries are likely to become recombination centers, trapping carriers and causing a decrease in the on-current of a transistor or a decrease in the field effect mobility. Therefore, the CAAC-OS in which clear grain boundaries are not confirmed is one of the crystalline oxides having a crystal structure suitable for the semiconductor layer of a transistor. In addition, a structure containing Zn is preferable for forming the CAAC-OS. For example, In-Zn oxide and In-Ga-Zn oxide are preferable because they can suppress the generation of crystal grain boundaries more effectively than In oxide.

[0183] CAAC-OS also tends to have a layered crystal structure (also referred to as a layered structure) in which a layer containing indium and oxygen (hereinafter, In layer) and a layer containing element M, zinc, and oxygen (hereinafter, (M, Zn) layer) are stacked. Note that indium and element M can be substituted for each other, and when element M in an (M, Zn) layer is substituted for indium, it can also be expressed as an (In, M, Zn) layer. When indium in an In layer is substituted for element M, it can also be expressed as an (In, M) layer.

[0184] CAAC-OS is a metal oxide with high crystallinity. On the other hand, it is difficult to confirm clear crystal boundaries in CAAC-OS, so it can be said that the decrease in electron mobility caused by crystal boundaries is unlikely to occur. In addition, since the crystallinity of metal oxides can be decreased by the inclusion of impurities or the generation of defects, CAAC-OS can be said to be a metal oxide with few impurities and defects (oxygen vacancies, etc.). Therefore, metal oxides with CAAC-OS have stable physical properties. As a result, metal oxides with CAAC-OS are resistant to heat and highly reliable.

[0185] The nc-OS has periodic atomic arrangement in a microscopic region (for example, a region of 1 nm to 10 nm, particularly a region of 1 nm to 3 nm). In addition, the nc-OS does not show regularity in the crystal orientation between different nanocrystals. Therefore, no orientation is seen throughout the film. Therefore, depending on the analysis method, the nc-OS may be indistinguishable from an a-like OS or an amorphous oxide semiconductor.

[0186] In-Ga-Zn oxide (hereinafter referred to as IGZO), a type of metal oxide containing indium, gallium, and zinc, may have a stable structure when made into the above-mentioned nanocrystals. In particular, since IGZO tends to have difficulty in crystal growth in the atmosphere, it may be structurally more stable when made into small crystals (for example, the above-mentioned nanocrystals) rather than large crystals (here, crystals of several mm or several cm).

[0187] The a-like OS is a metal oxide having a structure between the nc-OS and an amorphous oxide semiconductor. The a-like OS has a pore or low-density region. That is, the a-like OS has lower crystallinity than the nc-OS and CAAC-OS.

[0188] Oxide semiconductors (metal oxides) have a variety of structures and each structure has different characteristics. The oxide semiconductor of one embodiment of the present invention may include two or more of an amorphous oxide semiconductor, a polycrystalline oxide semiconductor, an a-like OS, an nc-OS, and a CAAC-OS.

[0189] In addition, for the semiconductor layer of the transistor disclosed in one aspect of the present invention, the above-described non-single crystal oxide semiconductor can be preferably used. Further, as the non-single crystal oxide semiconductor, nc-OS or CAAC-OS can be preferably used.

[0190] Note that the semiconductor layer may be a mixed film having two or more of a CAAC-OS region, a polycrystalline oxide semiconductor region, an nc-OS region, a pseudo-amorphous oxide semiconductor region, and an amorphous oxide semiconductor region. The mixed film may have, for example, a single-layer structure or a laminated structure including any two or more of the above-described regions.

[0191] Also, it is preferable to use CAC-OS (Cloud-Aligned Composite oxide semiconductor) for the semiconductor layer of the transistor disclosed in one aspect of the present invention. By using CAC-OS, high electrical characteristics or high reliability can be imparted to the transistor.

[0192] <Configuration of CAC-OS> Hereinafter, the configuration of CAC (Cloud-Aligned Composite)-OS that can be used for the transistor disclosed in one aspect of the present invention will be described.

[0193] CAC-OS has a conductive function in a part of the material and an insulating function in a part of the material, and has a semiconductor function as a whole. When CAC-OS is used for the active layer of a transistor, the conductive function is a function of flowing electrons (or holes) serving as carriers, and the insulating function is a function of not flowing electrons serving as carriers. By causing the conductive function and the insulating function to act complementarily, respectively, a switching function (On / Off function) can be imparted to CAC-OS. In CAC-OS, by separating each function, both functions can be enhanced to the maximum extent.

[0194] The CAC-OS has a conductive region and an insulating region. The conductive region has the above-mentioned conductive function, and the insulating region has the above-mentioned insulating function. In the material, the conductive region and the insulating region may be separated at the nanoparticle level. In addition, the conductive region and the insulating region may be unevenly distributed in the material. In addition, the conductive region may be observed to be connected in a cloud shape with a blurred periphery.

[0195] In addition, in the CAC-OS, the conductive regions and the insulating regions may each be dispersed in the material with a size of 0.5 nm or more and 10 nm or less, preferably 0.5 nm or more and 3 nm or less.

[0196] In addition, the CAC-OS is composed of components having different band gaps. For example, the CAC-OS is composed of a component having a wide gap due to an insulating region and a component having a narrow gap due to a conductive region. In this configuration, when carriers are caused to flow, the carriers mainly flow in the component having the narrow gap. In addition, the component having the narrow gap acts complementarily to the component having the wide gap, and carriers also flow in the component having the wide gap in conjunction with the component having the narrow gap. Therefore, when the above-mentioned CAC-OS is used in the channel formation region of a transistor, a high current driving force, that is, a large on-current and a high field effect mobility can be obtained in the on-state of the transistor.

[0197] That is, CAC-OS can also be called a matrix composite or a metal matrix composite.

[0198] The metal oxide preferably contains at least indium, particularly indium and zinc, and may further contain one or more elements selected from aluminum, gallium, yttrium, copper, vanadium, beryllium, boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, and the like.

[0199] IGZO is a common name and may refer to a compound made of In, Ga, Zn, and O. A typical example is InGaO 3 (ZnO) m1 (m1 is a natural number), or In (1+x0) Ga (1-x0) O 3 (ZnO) m0 (-1≦x0≦1, m0 is an arbitrary number).

[0200] The crystalline compound has a single crystal structure, a polycrystalline structure, or a CAAC structure, where multiple IGZO nanocrystals have a c-axis orientation and are connected without being oriented in the ab plane.

[0201] On the other hand, CAC-OS is a material composition of metal oxide. CAC-OS is a material composition containing In, Ga, Zn, and O, in which some regions observed as nanoparticles mainly composed of Ga and some regions observed as nanoparticles mainly composed of In are randomly dispersed in a mosaic pattern. Therefore, in CAC-OS, the crystal structure is a secondary element.

[0202] In addition, when one or more elements selected from aluminum, yttrium, copper, vanadium, beryllium, boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, etc. are contained instead of gallium, the CAC-OS has a configuration in which some regions observed to be in the form of nanoparticles mainly composed of the metal element and some regions observed to be in the form of nanoparticles mainly composed of In are randomly dispersed in a mosaic pattern.

[0203] CAC-OS can be formed, for example, by a sputtering method under conditions where the substrate is not intentionally heated. When CAC-OS is formed by a sputtering method, any one or more selected from an inert gas (typically argon), oxygen gas, and nitrogen gas may be used as a deposition gas. The lower the flow rate ratio of oxygen gas to the total flow rate of deposition gas during deposition, the more preferable it is, and for example, the flow rate ratio of oxygen gas is preferably 0% or more and less than 30%, and more preferably 0% or more and 10% or less.

[0204] In addition, semiconductor elements using CAC-OS have high reliability, making CAC-OS ideal for a variety of semiconductor devices including displays.

[0205] In addition, since a transistor having a CAC-OS semiconductor layer has high field-effect mobility and high driving capability, a display device with a narrow frame width (also called a narrow frame) can be provided by using the transistor in a driver circuit, typically a scan line driver circuit that generates a gate signal. In addition, a display device with a small number of wirings connected to the display device can be provided by using the transistor in a signal line driver circuit (particularly, a demultiplexer connected to an output terminal of a shift register in the signal line driver circuit).

[0206] Moreover, unlike transistors using low-temperature polysilicon, transistors having CAC-OS in the semiconductor layer do not require a laser crystallization process. Therefore, even in display devices using large-area substrates, it is possible to reduce manufacturing costs. Furthermore, in large display devices with high resolution such as ultra-high vision ("4K resolution", "4K2K", "4K") and super-high vision ("8K resolution", "8K4K", "8K"), by using transistors having CAC-OS in the semiconductor layer in the driving circuit and display section, writing can be performed in a short time and display defects can be reduced, which is preferable.

[0207] In addition, when focusing on the crystal structure, oxide semiconductors may be classified differently from the above. Here, the classification of the crystal structure of oxide semiconductors will be explained. As a representative example, the classification of the crystal structure of IGZO (a metal oxide containing In, Ga, and Zn) will be explained.

[0208] IGZO is broadly classified into Amorphous, Crystalline, and Crystal. Amorphous also includes completely amorphous. Crystalline also includes CAAC, nc, and CAC. Crystalline does not include single crystal, poly crystal, and completely amorphous. Crystal also includes single crystal and poly crystal.

[0209] The structure classified as Crystalline is an intermediate state between Amorphous and Crystal, and belongs to the new boundary region (New crystalline phase). The structure is in the boundary region between Amorphous and Crystal. In other words, the structure is completely different from the energetically unstable Amorphous and Crystal.

[0210] The crystal structure of the film or substrate can be evaluated using an X-ray diffraction (XRD) image.

[0211] As an example, the peak shape of the XRD spectrum of quartz glass is nearly symmetrical. On the other hand, the peak shape of the XRD spectrum of crystalline IGZO is asymmetrical. The asymmetrical shape of the peak in the XRD spectrum clearly indicates the presence of crystals. In other words, if the peak shape of the XRD spectrum is not symmetrical, it cannot be said to be amorphous. It is presumed that the asymmetrical shape of the peak in the XRD spectrum of crystalline IGZO is due to the crystalline phase (microcrystals).

[0212] Specifically, crystalline IGZO has a peak at or near 2θ=34° in an XRD spectrum. Microcrystals have a peak at or near 2θ=31°. When an oxide semiconductor film is evaluated using X-ray diffraction, the spectrum width on the low-angle side is wider than the peak at or near 2θ=34°. This suggests that the oxide semiconductor film contains microcrystals having a peak at or near 2θ=31°.

[0213] The crystal structure of the film can be evaluated from the diffraction pattern (also called the nanobeam electron diffraction pattern) observed by nanobeam electron diffraction (NBED). In nanobeam electron diffraction, electron diffraction is performed with a probe diameter of, for example, 1 nm. The diffraction pattern of an IGZO film formed by sputtering at room temperature on the substrate shows a spot-like pattern rather than a halo. For this reason, it is presumed that an IGZO film formed at room temperature is in an intermediate state that is neither crystalline nor amorphous, and therefore cannot be concluded to be amorphous.

[0214] Alternatively, silicon may be used for the semiconductor in which the channel of the transistor is formed. Although amorphous silicon may be used as the silicon, it is preferable to use silicon having crystallinity. For example, it is preferable to use microcrystalline silicon, polycrystalline silicon, single crystal silicon, or the like. In particular, polycrystalline silicon can be formed at a lower temperature than single crystal silicon, and has higher field effect mobility and higher reliability than amorphous silicon.

[0215] [Conductive Layer] Materials that can be used for conductive layers such as the gate, source, and drain of a transistor, as well as various wirings and electrodes that constitute a display device include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, or alloys containing these as main components. Films containing these materials can be used as a single layer or a laminated structure. For example, there are a single layer structure of an aluminum film containing silicon, a two-layer structure in which an aluminum film is laminated on a titanium film, a two-layer structure in which an aluminum film is laminated on a tungsten film, a two-layer structure in which a copper film is laminated on a copper-magnesium-aluminum alloy film, a two-layer structure in which a copper film is laminated on a titanium film, a two-layer structure in which a copper film is laminated on a tungsten film, a three-layer structure in which a titanium film or titanium nitride film is laminated on the titanium film or titanium nitride film, and a three-layer structure in which an aluminum film or copper film is laminated on the titanium film or titanium nitride film, and a three-layer structure in which an aluminum film or copper film is laminated on the molybdenum film or molybdenum nitride film is laminated on the molybdenum film or molybdenum nitride film is laminated on the molybdenum film or molybdenum nitride film. Alternatively, oxides such as indium oxide, tin oxide, zinc oxide, etc. may be used. Furthermore, copper containing manganese is preferably used because it enhances the controllability of the shape by etching.

[0216] [Insulating layer] Examples of insulating materials that can be used for each insulating layer include resins such as acrylic and epoxy, resins having siloxane bonds, and inorganic insulating materials such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide.

[0217] Moreover, the light emitting element is preferably provided between a pair of insulating films with low water permeability, which can prevent impurities such as water from entering the light emitting element and suppress deterioration of the reliability of the device.

[0218] Examples of the insulating film having low water permeability include a film containing nitrogen and silicon, such as a silicon nitride film or a silicon nitride oxide film, and a film containing nitrogen and aluminum, such as an aluminum nitride film. In addition, a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, etc. may also be used.

[0219] For example, the water vapor permeability of a low-permeability insulating film is 1×10 -5 [g / (m 2 ·day)] or less, preferably 1 × 10 -6 [g / (m 2 ·day)] or less, preferably 1×10 -7 [g / (m 2 ·day)] or less, and more preferably 1×10 -8 [g / (m 2 ·day)] or less.

[0220] The above is a description of the components.

[0221] At least a part of the configuration examples exemplified in this embodiment and the corresponding drawings can be implemented in appropriate combination with other configuration examples or drawings.

[0222] This embodiment mode can be implemented by appropriately combining at least a part of it with other embodiment modes described in this specification.

[0223] (Embodiment 3) In this embodiment, a configuration example of a display device will be described with reference to FIG.

[0224] 12A includes a pixel portion 502, a driver circuit portion 504, a protective circuit 506, and a terminal portion 507. Note that the protective circuit 506 does not necessarily have to be provided.

[0225] The pixel section 502 has a plurality of pixel circuits 501 arranged in X rows and Y columns (X and Y are each independently a natural number of 2 or more). Each pixel circuit 501 has a circuit for driving a display element.

[0226] The driver circuit unit 504 has driver circuits such as a gate driver 504a that outputs scanning signals to the gate lines GL_1 to GL_X and a source driver 504b that supplies data signals to the data lines DL_1 to DL_Y. The gate driver 504a may have at least a shift register. The source driver 504b is configured using, for example, a plurality of analog switches. The source driver 504b may also be configured using a shift register.

[0227] The terminal portion 507 refers to a portion provided with terminals for inputting power, control signals, image signals, and the like from an external circuit to the display device.

[0228] The protection circuit 506 is a circuit that, when a potential outside a certain range is applied to a wiring connected to the protection circuit 506, brings the wiring into a conductive state with another wiring. The protection circuit 506 shown in Fig. 12A is connected to various wirings, such as a gate line GL that is a wiring between a gate driver 504a and a pixel circuit 501, or a data line DL that is a wiring between a source driver 504b and a pixel circuit 501. Note that in Fig. 12A, the protection circuit 506 is hatched to distinguish it from the pixel circuit 501.

[0229] In addition, the gate driver 504a and the source driver 504b may be provided on the same substrate as the pixel unit 502, or a substrate on which a gate driver circuit or a source driver circuit is separately formed (e.g., a drive circuit substrate formed of a single crystal semiconductor or a polycrystalline semiconductor) may be mounted on the substrate by COG or TAB (Tape Automated Bonding).

[0230] 12B and 12C show an example of a pixel circuit configuration that can be applied to the pixel circuit 501. In FIG.

[0231] 12B includes a liquid crystal element 570, a transistor 550, and a capacitor 560. The pixel circuit 501 is connected to a data line DL_n, a gate line GL_m, a potential supply line VL, and the like.

[0232] The potential of one of a pair of electrodes of the liquid crystal element 570 is set as appropriate according to the specifications of the pixel circuit 501. The orientation state of the liquid crystal element 570 is set by written data. Note that a common potential (common potential) may be applied to one of the pair of electrodes of the liquid crystal element 570 included in each of the multiple pixel circuits 501. Also, different potentials may be applied to one of the pair of electrodes of the liquid crystal element 570 in the pixel circuits 501 in each row.

[0233] 12C includes a transistor 552, a transistor 554, a capacitor 562, and a light-emitting element 572. The pixel circuit 501 is connected to a data line DL_n, a gate line GL_m, a potential supply line VL_a, a potential supply line VL_b, and the like.

[0234] A high power supply potential VDD is applied to one of the potential supply lines VL_a and VL_b, and a low power supply potential VSS is applied to the other. A current flowing through the light emitting element 572 is controlled in accordance with a potential applied to the gate of the transistor 554, thereby controlling the light emission luminance of the light emitting element 572.

[0235] At least a part of the configuration examples exemplified in this embodiment and the corresponding drawings can be implemented in appropriate combination with other configuration examples or drawings.

[0236] This embodiment mode can be implemented by appropriately combining at least a part of it with other embodiment modes described in this specification.

[0237] (Embodiment 4) In the following, a pixel circuit including a memory for correcting a gray scale displayed in a pixel and a display device having the same will be described.

[0238] [Circuit configuration] 13A shows a circuit diagram of a pixel circuit 400. The pixel circuit 400 includes a transistor M1, a transistor M2, a capacitor C1, and a circuit 401. The pixel circuit 400 is connected to a wiring S1, a wiring S2, a wiring G1, and a wiring G2.

[0239] The transistor M1 has a gate connected to the wiring G1, one of a source and a drain connected to the wiring S1, and the other connected to one electrode of the capacitor C1. The transistor M2 has a gate connected to the wiring G2, one of a source and a drain connected to the wiring S2, and the other connected to the other electrode of the capacitor C1 and the circuit 401.

[0240] The circuit 401 is a circuit including at least one display element. Various elements can be used as the display element, but typically, a light-emitting element such as an organic EL element or an LED element, a liquid crystal element, or a MEMS (Micro Electro Mechanical Systems) element can be used.

[0241] The node connecting the transistor M1 and the capacitor C1 is referred to as a node N1, and the node connecting the transistor M2 and the circuit 401 is referred to as a node N2.

[0242] In the pixel circuit 400, the potential of the node N1 can be maintained by turning off the transistor M1. Also, the potential of the node N2 can be maintained by turning off the transistor M2. Also, by writing a predetermined potential to the node N1 via the transistor M1 while the transistor M2 is in the off state, the potential of the node N2 can be changed according to the change in the potential of the node N1 due to capacitive coupling via the capacitor C1.

[0243] Here, the transistor including an oxide semiconductor, as exemplified in Embodiment 1, can be used as one or both of the transistor M1 and the transistor M2. Therefore, the potentials of the nodes N1 and N2 can be held for a long period of time due to an extremely low off-state current. Note that when the period during which the potentials of the nodes are held is short (specifically, when the frame frequency is 30 Hz or more), a transistor including a semiconductor such as silicon may be used.

[0244] [Driving method example] Next, an example of an operation method of the pixel circuit 400 will be described with reference to Fig. 13B. Fig. 13B is a timing chart relating to the operation of the pixel circuit 400. Note that, for ease of explanation, the influence of various resistances such as wiring resistance, parasitic capacitances of transistors and wiring, threshold voltages of transistors, and the like will not be taken into consideration here.

[0245] 13B, one frame period is divided into a period T1 and a period T2. The period T1 is a period in which a potential is written to the node N2, and the period T2 is a period in which a potential is written to the node N1.

[0246] [Period T1] In the period T1, a potential that turns on the transistor is applied to both the wiring G1 and the wiring G2. In addition, a fixed potential V ref is supplied to the line S2, and the first data potential V w supplies.

[0247] The node N1 is connected to a potential V ref The node N2 is supplied with a first data potential V w Therefore, the capacitance C1 has a potential difference V w -V ref is held.

[0248] [Period T2] In the next period T2, a potential that turns on the transistor M1 is applied to the wiring G1, and a potential that turns off the transistor M2 is applied to the wiring G2. data A predetermined constant potential is applied to the wiring S2, or the wiring S2 may be in a floating state.

[0249] The node N1 receives a second data potential V data At this time, the second data potential V data In response to this, the potential of the node N2 changes by a potential dV. w The potential obtained by adding the second data potential V to the potential dV is input. Note that, although the potential dV is shown to be a positive value in FIG. 13B, it may be a negative value. That is, the second data potential V data is the potential V ref It may be lower.

[0250] Here, the potential dV is roughly determined by the capacitance value of the capacitor C1 and the capacitance value of the circuit 401. When the capacitance value of the capacitor C1 is sufficiently larger than the capacitance value of the circuit 401, the potential dV is equal to the second data potential V data The potential becomes close to

[0251] In this manner, the pixel circuit 400 can generate a potential to be supplied to the circuit 401 including a display element by combining two types of data signals, and therefore, it is possible to perform gray scale correction within the pixel circuit 400.

[0252] In addition, the pixel circuit 400 can generate a potential that exceeds the maximum potential that can be supplied to the wirings S1 and S2. For example, when a light-emitting element is used, high dynamic range (HDR) display or the like can be performed. When a liquid crystal element is used, overdrive driving or the like can be realized.

[0253] [Example of application] [Example using liquid crystal element] The pixel circuit 400LC shown in Fig. 13C includes a circuit 401LC. The circuit 401LC includes a liquid crystal element LC and a capacitor C2.

[0254] The liquid crystal element LC has one electrode connected to the node N2 and one electrode connected to the capacitance C2, and the other electrode connected to the potential V com2 The other electrode of the capacitor C2 is connected to the wiring to which the potential V com1 Connect with the wiring given.

[0255] The capacitor C2 functions as a storage capacitor. If the capacitor C2 is not required, it can be omitted.

[0256] The pixel circuit 400LC can supply a high voltage to the liquid crystal element LC, and therefore can, for example, realize high-speed display by overdrive driving, apply a liquid crystal material with a high driving voltage, etc. In addition, by supplying a correction signal to the wiring S1 or wiring S2, it is possible to correct the gradation according to the operating temperature, the deterioration state of the liquid crystal element LC, etc.

[0257] [Example using light-emitting element] 13D includes a circuit 401EL. The circuit 401EL includes a light-emitting element EL, a transistor M3, and a capacitor C2.

[0258] The transistor M3 has a gate connected to the node N2 and one electrode of the capacitor C2, and a source and a drain connected to the potential V H The other electrode of the capacitor C2 is connected to a wiring to which a potential V com The light-emitting element EL has the other electrode connected to a wiring that is supplied with a potential V L Connect with the wiring given.

[0259] The transistor M3 has a function of controlling the current supplied to the light-emitting element EL. The capacitor C2 functions as a storage capacitor. The capacitor C2 can be omitted if not required.

[0260] In this embodiment, the anode side of the light-emitting element EL is connected to the transistor M3, but the cathode side of the light-emitting element EL may be connected to the transistor M3. H and potential V L The value of can be changed appropriately.

[0261] In the pixel circuit 400EL, a large current can be passed through the light-emitting element EL by applying a high potential to the gate of the transistor M3, and thus, for example, HDR display can be realized. In addition, by supplying a correction signal to the wiring S1 or the wiring S2, it is also possible to correct variations in the electrical characteristics of the transistor M3 and the light-emitting element EL.

[0262] Note that the circuits are not limited to those illustrated in FIGS. 13C and 13D, and may be configured to include additional transistors, capacitors, and the like.

[0263] This embodiment mode can be implemented by appropriately combining at least a part of it with other embodiment modes described in this specification.

[0264] (Embodiment 5) A configuration example of a pixel in a display panel of one embodiment of the present invention will be described below.

[0265] 14A to 14E show examples of the configuration of the pixel 300. In FIG.

[0266] The pixel 300 has a plurality of pixels 301. Each of the plurality of pixels 301 functions as a sub-pixel. Since one pixel 300 is composed of a plurality of pixels 301 each exhibiting a different color, full color display can be performed on the display unit.

[0267] Each of the pixels 300 shown in Figures 14A and 14B has three sub-pixels. The pixel 301 in the pixel 300 shown in Figure 14A exhibits a color combination of red (R), green (G), and blue (B). The pixel 301 in the pixel 300 shown in Figure 14B exhibits a color combination of cyan (C), magenta (M), and yellow (Y).

[0268] Each of the pixels 300 shown in Figures 14C to 14E has four sub-pixels. The pixel 301 of the pixel 300 shown in Figure 14C has a color combination of red (R), green (G), blue (B), and white (W). By using a sub-pixel that has white, the luminance of the display unit can be increased. The pixel 301 of the pixel 300 shown in Figure 14D has a color combination of red (R), green (G), blue (B), and yellow (Y). The pixel 301 of the pixel 300 shown in Figure 14E has a color combination of cyan (C), magenta (M), yellow (Y), and white (W).

[0269] By increasing the number of sub-pixels that function as one pixel and appropriately combining sub-pixels that exhibit colors such as red, green, blue, cyan, magenta, and yellow, it is possible to improve the reproducibility of intermediate tones, thereby improving the display quality.

[0270] In addition, the display device according to one embodiment of the present invention can reproduce color gamuts of various standards. For example, the color gamuts can be reproduced according to the PAL (Phase Alternating Line) standard and the NTSC (National Television System Committee) standard used in television broadcasting, the sRGB (standard RGB) standard and the Adobe RGB standard widely used in display devices used in electronic devices such as personal computers, digital cameras, and printers, the ITU-R BT.709 (International Telecommunication Union Radiocommunication Sector Broadcasting Service (Television) 709) standard used in HDTV (High Definition Television, also called high vision), the DCI-P3 (Digital Cinema Initiatives P3) standard used in digital cinema projection, and the ITU-R BT.2020 (REC.2020 (Recommendation 2020)) standard used in UHDTV (Ultra High Definition Television, also called super high vision).

[0271] Moreover, when the pixels 300 are arranged in a matrix of 1920×1080, a display device capable of full-color display at a resolution of so-called full high-definition (also called "2K resolution", "2K1K", or "2K"). When the pixels 300 are arranged in a matrix of 3840×2160, for example, a display device capable of full-color display at a resolution of so-called ultra high-definition (also called "4K resolution", "4K2K", or "4K"). When the pixels 300 are arranged in a matrix of 7680×4320, for example, a display device capable of full-color display at a resolution of so-called super high-definition (also called "8K resolution", "8K4K", or "8K"). By increasing the number of pixels 300, a display device capable of full-color display at a resolution of 16K or 32K can also be realized.

[0272] This embodiment mode can be implemented by appropriately combining at least a part of it with other embodiment modes described in this specification.

[0273] (Embodiment 6) In this embodiment, examples of electronic devices to which the display device of one embodiment of the present invention can be applied will be described.

[0274] Electronic device 6500 shown in FIG. 15A is a portable information terminal that can be used as a smartphone.

[0275] The electronic device 6500 includes a housing 6501, a display portion 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, and a light source 6508. The display portion 6502 has a touch panel function.

[0276] The display device of one embodiment of the present invention can be applied to the display portion 6502.

[0277] The display portion 6502 has a cutout portion, and a camera 6507 and a light source 6508 are provided so as to engage with the cutout portion. With this structure, the area occupied by the display portion 6502 with respect to the housing 6501 can be increased.

[0278] 15B shows an example in which the display portion 6502 has an opening, and a camera 6507 and a ring-shaped light source 6509 surrounding the camera 6507 are disposed inside the opening. A speaker 6505 is provided so as to engage with a notch in the display portion 6502. The display portion 6502 may be used as a light source for illuminating a subject. With this configuration, the area occupied by the display portion 6502 relative to the housing 6501 can be made larger.

[0279] FIG. 15C is a schematic cross-sectional view including the end of the housing 6501 on the microphone 6506 side.

[0280] A light-transmitting protective member 6510 is provided on the display surface side of the housing 6501, and a display panel 6511, optical members 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, etc. are arranged in the space surrounded by the housing 6501 and the protective member 6510.

[0281] A display panel 6511, an optical member 6512, and a touch sensor panel 6513 are fixed to the protective member 6510 by adhesive layers (not shown).

[0282] A part of the display panel 6511 is folded back in an area outside the display unit 6502. An FPC 6515 is connected to the folded back part. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to a terminal provided on a printed circuit board 6517.

[0283] The flexible display panel of one embodiment of the present invention can be applied to the display panel 6511. Therefore, an extremely lightweight electronic device can be realized. In addition, since the display panel 6511 is extremely thin, a large-capacity battery 6518 can be mounted thereon while keeping the thickness of the electronic device small. In addition, by folding back a part of the display panel 6511 and arranging a connection portion with the FPC 6515 on the back side of the pixel portion, an electronic device with a narrow frame can be realized.

[0284] This embodiment mode can be implemented by appropriately combining at least a part of it with other embodiment modes described in this specification.

[0285] (Embodiment 7) In this embodiment, electronic devices including a display device manufactured according to one embodiment of the present invention will be described.

[0286] The electronic devices exemplified below each have a display device according to one embodiment of the present invention in a display portion. Therefore, the electronic devices have high resolution. In addition, the electronic devices can have both high resolution and a large screen.

[0287] The display portion of the electronic device according to one embodiment of the present invention can display images with a resolution of, for example, full high definition, 4K2K, 8K4K, 16K8K, or higher.

[0288] Examples of electronic devices include electronic devices with relatively large screens such as television devices, notebook personal computers, monitor devices, digital signage, pachinko machines, and game machines, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and audio playback devices.

[0289] An electronic device to which one embodiment of the present invention is applied can be incorporated along a flat or curved surface of an inner or outer wall of a house or building, or the interior or exterior of an automobile or the like.

[0290] FIG. 16A is a diagram showing the appearance of the camera 8000 with the viewfinder 8100 attached.

[0291] The camera 8000 includes a housing 8001, a display unit 8002, an operation button 8003, a shutter button 8004, etc. In addition, a detachable lens 8006 is attached to the camera 8000.

[0292] In addition, the camera 8000 may have the lens 8006 and the housing integrated together.

[0293] The camera 8000 can capture an image by pressing a shutter button 8004 or touching a display unit 8002 that functions as a touch panel.

[0294] The housing 8001 has a mount having electrodes, and can be connected to a strobe device or the like in addition to the finder 8100 .

[0295] The finder 8100 includes a housing 8101, a display portion 8102, a button 8103, and the like.

[0296] The housing 8101 is attached to the camera 8000 by a mount that engages with the mount of the camera 8000. The viewfinder 8100 can display an image received from the camera 8000 on a display unit 8102.

[0297] The button 8103 has a function such as a power button.

[0298] The display device of one embodiment of the present invention can be applied to a display portion 8002 of a camera 8000 and a display portion 8102 of a viewfinder 8100. Note that the camera 8000 may have a built-in viewfinder.

[0299] FIG. 16B is a diagram showing the external appearance of the head mounted display 8200.

[0300] The head mounted display 8200 includes a mounting portion 8201, a lens 8202, a main body 8203, a display portion 8204, and a cable 8205. The mounting portion 8201 includes a built-in battery 8206.

[0301] A cable 8205 supplies power from a battery 8206 to a main body 8203. The main body 8203 includes a wireless receiver or the like and can display received video information on a display portion 8204. The main body 8203 also includes a camera and can use information on the movements of the user's eyeballs and eyelids as an input means.

[0302] The mounting unit 8201 may have a function of recognizing the line of sight by providing a plurality of electrodes at positions that contact the user, capable of detecting a current that flows with the movement of the user's eyeballs. The mounting unit 8201 may also have a function of monitoring the user's pulse rate based on the current that flows through the electrodes. The mounting unit 8201 may also have various sensors, such as a temperature sensor, a pressure sensor, and an acceleration sensor, and may have a function of displaying the user's biological information on the display unit 8204 and a function of changing the image displayed on the display unit 8204 according to the movement of the user's head.

[0303] The display device of one embodiment of the present invention can be applied to the display portion 8204.

[0304] 16C, 16D, and 16E are diagrams showing the external appearance of a head mounted display 8300. The head mounted display 8300 includes a housing 8301, a display unit 8302, a band-shaped fixture 8304, and a pair of lenses 8305.

[0305] A user can view the display on the display unit 8302 through the lens 8305. Note that it is preferable to arrange the display unit 8302 in a curved manner because the user can feel a high sense of presence. In addition, by viewing another image displayed in a different area of ​​the display unit 8302 through the lens 8305, it is possible to perform three-dimensional display using parallax. Note that the present invention is not limited to a configuration in which one display unit 8302 is provided, and two display units 8302 may be provided, with one display unit being provided for each eye of the user.

[0306] Note that the display device of one embodiment of the present invention can be applied to the display portion 8302. A display device including the semiconductor device of one embodiment of the present invention has extremely high definition, so that a user cannot see pixels even when the image is enlarged using a lens 8305 as in FIG.

[0307] The electronic device shown in Figures 17A to 17G has a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or an operation switch), a connection terminal 9006, a sensor 9007 (including a function to measure force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor or infrared rays), a microphone 9008, etc.

[0308] The electronic device shown in Fig. 17A to Fig. 17G has various functions. For example, it can have a function of displaying various information (still images, videos, text images, etc.) on the display unit, a touch panel function, a function of displaying a calendar, date or time, a function of controlling processing by various software (programs), a wireless communication function, a function of reading and processing a program or data recorded on a recording medium, etc. The functions of the electronic device are not limited to these, and it can have various functions. The electronic device may have multiple display units. In addition, the electronic device may have a function of providing a camera or the like to capture still images and videos and store them on a recording medium (external or built-in to the camera), a function of displaying the captured images on the display unit, etc.

[0309] The electronic device shown in FIGS. 17A to 17G will be described in detail below.

[0310] 17A is a perspective view showing a television device 9100. The television device 9100 can incorporate a display unit 9001 having a large screen, for example, 50 inches or more, or 100 inches or more.

[0311] FIG. 17B is a perspective view showing a mobile information terminal 9101. The mobile information terminal 9101 can be used as, for example, a smartphone. The mobile information terminal 9101 may be provided with a speaker 9003, a connection terminal 9006, a sensor 9007, and the like. The mobile information terminal 9101 can display text and image information on a plurality of surfaces. FIG. 17B shows an example in which three icons 9050 are displayed. Information 9051 shown in a dashed rectangle can also be displayed on another surface of the display unit 9001. Examples of the information 9051 include notifications of incoming e-mail, SNS, and phone calls, titles of e-mail and SNS, sender names, date and time, time, remaining battery level, and antenna reception strength. Alternatively, icons 9050 and the like may be displayed at the position where the information 9051 is displayed.

[0312] 17C is a perspective view showing a mobile information terminal 9102. The mobile information terminal 9102 has a function of displaying information on three or more sides of the display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different sides. For example, a user can check information 9053 displayed in a position that can be observed from above the mobile information terminal 9102 while the mobile information terminal 9102 is stored in a breast pocket of clothes. The user can check the display without taking the mobile information terminal 9102 out of the pocket and decide, for example, whether to answer a call.

[0313] 17D is a perspective view showing a wristwatch-type mobile information terminal 9200. The display surface of the display unit 9001 is curved, and display can be performed along the curved display surface. The mobile information terminal 9200 can also perform hands-free conversation by communicating with a headset capable of wireless communication, for example. The mobile information terminal 9200 can also perform data transmission and charging with another information terminal through a connection terminal 9006. Charging may be performed by wireless power supply.

[0314] 17E, 17F, and 17G are perspective views showing a foldable mobile information terminal 9201. FIG. 17E is a perspective view of the mobile information terminal 9201 in an unfolded state, FIG. 17G is a perspective view of the mobile information terminal 9201 in a folded state, and FIG. 17F is a perspective view of the mobile information terminal 9201 in a state in which the mobile information terminal 9201 is changing from one of FIG. 17E and FIG. 17G to the other. The mobile information terminal 9201 has excellent portability in a folded state, and has excellent viewability of the display due to a seamless wide display area in an unfolded state. The display unit 9001 of the mobile information terminal 9201 is supported by three housings 9000 connected by hinges 9055. For example, the display unit 9001 can be bent with a curvature radius of 1 mm or more and 150 mm or less.

[0315] 18A shows an example of a television device. A television device 7100 has a display unit 7500 built into a housing 7101. Here, the housing 7101 is supported by a stand 7103.

[0316] 18A can be operated using an operation switch provided on the housing 7101 or a separate remote control 7111. Alternatively, a touch panel may be applied to the display portion 7500, and the television set 7100 may be operated by touching the touch panel. The remote control 7111 may have a display portion in addition to operation buttons.

[0317] The television device 7100 may also include a television broadcast receiver and a communication device for network connection.

[0318] 18B shows a laptop personal computer 7200. The laptop personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, and the like. A display unit 7500 is incorporated in the housing 7211.

[0319] 18C and 18D show an example of digital signage.

[0320] 18C includes a housing 7301, a display unit 7500, and a speaker 7303. The digital signage 7300 may further include an LED lamp, an operation key (including a power switch or an operation switch), a connection terminal, various sensors, a microphone, and the like.

[0321] 18D shows a digital signage 7400 attached to a cylindrical pole 7401. The digital signage 7400 has a display unit 7500 provided along the curved surface of the pole 7401.

[0322] The larger the display unit 7500, the more information can be provided at one time, and the larger the display area, the more easily it catches people's attention, which has the effect of increasing the effectiveness of advertising, for example.

[0323] It is preferable to apply a touch panel to the display unit 7500 so that the user can operate it. This allows the display unit 7500 to be used not only for advertising purposes, but also for providing information desired by the user, such as route information, traffic information, and commercial facility guide information.

[0324] 18C and 18D, it is preferable that the digital signage 7300 or the digital signage 7400 can wirelessly communicate with an information terminal 7311 such as a smartphone carried by a user. For example, advertising information displayed on the display unit 7500 can be displayed on the screen of the information terminal 7311, or the display on the display unit 7500 can be switched by operating the information terminal 7311.

[0325] Furthermore, a game using the information terminal 7311 as an operation means (controller) can be executed on the digital signage 7300 or the digital signage 7400. This allows an unspecified number of users to simultaneously participate in and enjoy the game.

[0326] The display device of one embodiment of the present invention can be applied to the display portion 7500 in FIGS. 18A to 18D. EXAMPLES

[0327] In this example, samples having different laminate structures were prepared, and the tensile modulus and flexural modulus were measured. The results are described below.

[0328] [Rating 1] 〔sample〕 In this example, a PEN (Polyethylene naphthalate) film having a thickness of 100 μm was used as a film simulating the films 11 and 12 exemplified in the above-mentioned embodiment 1. A silicone gel sheet was used as a viscoelastic sheet simulating the adhesive layer 21.

[0329] Table 1 shows the layered structures and thicknesses of each layer of the five samples prepared.

[0330] [Table 1]

[0331] Each of the samples A1, A2, and A3 has a structure in which a pair of PEN films is bonded with a viscoelastic sheet. The thickness of the viscoelastic sheet increases in the order of the sample A1, the sample A2, and the sample A3.

[0332] In addition, comparative samples Ref.1 and Ref.2 were prepared as comparative samples. Comparative sample Ref.1 was a single piece of PEN film. Comparative sample Ref.2 was a pair of PEN films bonded together with an adhesive whose main component was epoxy resin. A two-component epoxy resin was used as the epoxy resin.

[0333] [Measurement of Elastic Modulus] The tensile modulus was measured with reference to the Japanese Industrial Standards JIS 7127 and JIS K7161. The measurement device used was an EZ Graph made by Shimadzu Corporation. The interval between the sample grippers was 50 mm. Each sample was cut into a strip with a width of 10 mm.

[0334] The bending modulus was measured with reference to the Japanese Industrial Standard JIS 7171. Although this standard assumes that the sample thickness is 1 mm or more, the same method was used for samples thinner than this. Each sample was cut into a rectangular shape with a width of 25 mm. A three-point bending test was performed with the distance between the lower supports of the sample set to 40 mm.

[0335] The tensile modulus and flexural modulus were determined from the slope between two points, the stress when the strain was 0.05% and the stress when the strain was 0.25%, on the strain-stress curve measured by the above method.

[0336] 〔result〕 FIG. 19A shows the measurement results of the tensile modulus and flexural modulus of each sample.

[0337] First, looking at comparative sample Ref.1, the flexural modulus tends to be greater than the tensile modulus. Also, comparative sample Ref.2 has a smaller tensile modulus than comparative sample Ref.1, but a larger flexural modulus. This suggests that bonding two films together with an adhesive makes it more difficult to bend.

[0338] Next, when focusing on Sample A1, Sample A2, and Sample A3, unlike Comparative Sample Ref. 1 and Comparative Sample Ref. 2, the bending modulus was smaller than the tensile modulus, which indicates that the samples to which the viscoelastic sheet was applied can be bent with a small force.

[0339] Furthermore, it was confirmed from FIG. 19A that the thicker the viscoelastic sheet, the smaller the bending modulus.

[0340] Here, the value obtained by dividing the bending modulus by the tensile modulus (the ratio of bending modulus when the tensile modulus is set to 1) was 1.17 for comparative sample Ref.1 and 1.36 for comparative sample Ref.2, which are greater than 1, while it was extremely small, at 0.12 for sample A1, 0.10 for sample A2, and 0.06 for sample A3.

[0341] [Rating 2] Next, a sample having a layered structure different from the above was prepared and similarly evaluated.

[0342] 〔sample〕 Table 2 shows the layered structures and thicknesses of each layer of the three samples prepared.

[0343] [Table 2]

[0344] Sample B1 has a structure in which three PEN films are bonded with two viscoelastic sheets. Sample B2 has a structure in which a urethane sheet is bonded with an OCA (Optical Clear Adhesive) film to the above-mentioned sample A2. The OCA film is made of an acrylic resin material.

[0345] The comparative sample Ref.3 was made by bonding three PEN films together with epoxy resin.

[0346] The tensile modulus and flexural modulus were measured in the same manner as above.

[0347] 〔result〕 FIG. 19B shows the measurement results of the tensile modulus and flexural modulus of each sample.

[0348] Similar to the above-mentioned comparative sample Ref. 2, the comparative sample Ref. 3 showed a tendency for the flexural modulus to be higher than the tensile modulus. It was also confirmed that the flexural modulus value was larger than that of the comparative sample Ref. 2.

[0349] Next, looking at sample B1, although it was extremely thick at about 0.9 mm, it had an even smaller flexural modulus than samples A1 and A2.

[0350] In addition, the bending modulus of the sample B2 was smaller than the tensile modulus by at least one order of magnitude, similar to the sample A1, etc. From this result, it was confirmed that the effect was obtained even by applying a viscoelastic sheet only to a part of the laminate structure.

[0351] [Observation of sample shape] The following describes the results of observing the end portion of sample A1 while changing its shape.

[0352] Fig. 20A1 is a micrograph of the edge of sample A1 when sample A1 is flattened. Fig. 20A2 is a photograph obtained by image processing of Fig. 20A1 to enhance the contour. As shown in Fig. 20A1 and Fig. 20A2, when sample A1 is flat, the edges of the pair of PEN films and the edges of the viscoelastic sheet are roughly aligned.

[0353] Figures 20B1 and 20B2 are micrographs of sample A1 when it is bent 180 degrees with a diameter of 10 mm. Figures 20B1 and 20B2 show that the lower PEN film protrudes outward from the upper PEN film, and that the end faces of the viscoelastic sheet are stretched. It can also be seen that the end faces of the viscoelastic sheet are inclined relative to the end faces of the pair of PEN films and form a gentle arc.

[0354] Figures 20C1 and 20C2 are micrographs of sample A1 bent 180 degrees with a diameter of 3 mm. The shape is almost the same as when it is bent with a diameter of 10 mm. Thus, it was confirmed that the shape of the end of sample A1 hardly changes depending on the curvature. [Explanation of symbols]

[0355] 10, 10A, 10R: Display panel: 11, 12, 13: Film: 21, 21a, 21b: Adhesive layer: 21R: Adhesive: 26, 26a, 26b: FPC: 27, 27a, 27b: Connection body: 3 1, 31a, 31b: Support: 32: Adhesive layer: 33, 34a, 34b, 34c, 34d, 34e, 34f, 34g, 34h, 34j, 34k: Support: 35, 35a, 35b, 36: Connection part

Claims

1. A display device having a display element and a bendable display panel, The display panel includes a first film, a second film, an adhesive layer, and a substrate; On one surface side of the substrate, the adhesive layer is located between the first film and the second film and has a function of bonding the first film and the second film together; The display panel has a bending elastic modulus of 0.01 to less than 1 times the tensile elastic modulus, The adhesive layer has a thickness of 300 μm or more and 2 mm or less, The adhesive layer has viscoelasticity and is more stretchable than the first film and the second film; When the end of the first film is viewed in a direction perpendicular to the edge of the first film, the end of the second film has a region that protrudes outward from the end of the first film, the second film has a region where a touch sensor wiring is provided, a region where a transistor is formed, and a region that is folded back to the other surface side of the substrate, A display device, wherein when the display panel is curved, the neutral surface of the first film is located within the first film, the neutral surface of the second film is located within the second film, and the neutral surface of the display panel is located within the adhesive layer.

2. In claim 1, A display device, wherein a relaxation time for stress relaxation of the adhesive layer is 0.01 seconds or more and 10 seconds or less.

Images