JP2018013622A - Display device, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device or an electronic apparatus with high convenience, and a display device or an electronic apparatus capable of displaying an image in various ways.SOLUTION: A display device has a reflective first display element, and a second display element that emits light in an opposite direction to that in which the first display element emits light, an image to be displayed on each of a first display surface and a second display surface arranged back to back. A first transistor connected to the first display element and a second transistor connected to the second display element are formed on the same surface, and one of the first display element and the second display element is electrically connected to, through an opening provided in an insulating layer, the first transistor or second transistor.SELECTED DRAWING: Figure 4

Description

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

  Note that one embodiment of the present invention is not limited to the above technical field. Technical fields of one embodiment of the present invention disclosed in this specification and the like include semiconductor devices, display devices, light-emitting devices, power storage devices, memory devices, electronic devices, lighting devices, input devices, input / output devices, and driving methods thereof , Or a method for producing them, can be mentioned as an example.

  Note that in this specification and the like, a semiconductor device refers to any device that can function by utilizing semiconductor characteristics. A transistor, a semiconductor circuit, an arithmetic device, a memory device, or the like is one embodiment of a semiconductor device. In addition, an imaging device, an electro-optical device, a power generation device (including a thin film solar cell, an organic thin film solar cell, and the like) and an electronic device may include a semiconductor device.

  As one of display devices, there is a liquid crystal display device including a liquid crystal element. For example, an active matrix liquid crystal display device in which pixel electrodes are arranged in a matrix and a transistor is used as a switching element connected to each pixel electrode has attracted attention.

  For example, an active matrix liquid crystal display device using a transistor having a metal oxide channel formation region as a switching element connected to each pixel electrode is known (Patent Document 1 and Patent Document 2).

  Active matrix liquid crystal display devices are roughly classified into two types, a transmission type and a reflection type.

  The transmissive liquid crystal display device uses a backlight such as a cold cathode fluorescent lamp or an LED (Light Emitting Diode), and the light from the backlight transmits the liquid crystal by utilizing the optical modulation action of the liquid crystal. A state that is output to the outside and a state that is not output are selected, bright and dark display is performed, and further, they are combined to perform image display.

  In addition, the reflective liquid crystal display device utilizes the optical modulation action of the liquid crystal, and the external light, that is, the incident light is reflected by the pixel electrode and output to the outside of the device, and the incident light is not output to the outside of the device. An image is displayed by selecting a state, displaying bright and dark, and combining them. The reflective liquid crystal display device has an advantage of low power consumption because it does not use a backlight as compared with the transmissive liquid crystal display device.

JP 2007-123861 A JP 2007-96055 A

  In recent years, electronic devices including display devices have been diversified.

  An object of one embodiment of the present invention is to provide a highly convenient display device or electronic device. Another object is to provide a display device or an electronic device that can perform various displays. Another object is to provide a display device or an electronic device with reduced power consumption. Another object is to provide a display device or an electronic device that can display both a smooth moving image and a still image that is easy on the eyes. Another object is to provide a novel display device or an electronic device.

  Note that the description of these problems does not disturb the existence of other problems. In one embodiment of the present invention, it is not necessary to solve all of these problems. Issues other than the above can be extracted from the description of the specification and the like.

  The display device of one embodiment of the present invention includes a first display element, a second display element, a first display surface, and a second display surface. The first display element has a function of reflecting visible light to the first display surface side. The second display element has a function of emitting visible light to the second display surface side. The first display surface and the second display surface sandwich the first display element and the second display element and are located back to back.

  The display device of one embodiment of the present invention includes a first display element, a second display element, a first display surface, a second display surface, a first transistor, and a second transistor. And a first insulating layer. The first display element has a function of reflecting visible light to the first display surface side. The second display element has a function of emitting visible light to the second display surface side. The first display surface and the second display surface are positioned back to back with the first display element, the second display element, the first transistor, the second transistor, and the first insulating layer interposed therebetween. To do. The first transistor is electrically connected to the first display element, and the second transistor is electrically connected to the second display element. The first transistor and the second transistor are each formed on the first surface side of the first insulating layer. The first display element is located between the first insulating layer and the first display surface, and the second display element is located between the first insulating layer and the second display surface.

  The first display element is preferably a reflective liquid crystal element. The second display element is preferably an electroluminescent element.

  In the above, it is preferable to have a plurality of first display elements and a plurality of second display elements. At this time, it is preferable that the first display element and the second display element are arranged with the same definition. Alternatively, it is preferable that the first display element and the second display element are arranged with different definition.

  In the above, at least one of the first transistor and the second transistor preferably includes a metal oxide in a semiconductor layer in which a channel is formed.

  Another embodiment of the present invention is an electronic device including the above display device and a housing, and includes a first display portion and a second display portion that are positioned back to back. The first display unit has a function of displaying an image using reflected light, and the second display unit has a function of displaying an image using light emission. The housing preferably includes any one or more of an operation button, a speaker, a microphone, a camera, an external connection port, an antenna, and a sensor.

  According to one embodiment of the present invention, a highly convenient display device or electronic device can be provided. Alternatively, a display device or an electronic device that can perform various displays can be provided. Alternatively, a display device or an electronic device with reduced power consumption can be provided. Alternatively, it is possible to provide a display device or an electronic device that can display both a smooth moving image and a still image that is easy on the eyes. Alternatively, a novel display device or electronic device can be provided.

  Note that one embodiment of the present invention does not necessarily have all of these effects. In addition, effects other than these can be extracted from the description of the specification and the like.

3 shows a configuration example of a display device according to an embodiment. 3 shows a configuration example of a display device according to an embodiment. 3 shows a configuration example of a display device according to an embodiment. 3 shows a configuration example of a display device according to an embodiment. 3 shows a configuration example of a display device according to an embodiment. 3 shows a configuration example of a display device according to an embodiment. 3 shows a configuration example of a display device according to an embodiment. 3 shows a configuration example of a display device according to an embodiment. 8A to 8D illustrate a method for manufacturing a display device according to Embodiment. 8A to 8D illustrate a method for manufacturing a display device according to Embodiment. 8A to 8D illustrate a method for manufacturing a display device according to Embodiment. 8A to 8D illustrate a method for manufacturing a display device according to Embodiment. 3 shows a configuration example of a display device according to an embodiment. 3 shows a configuration example of a display device according to an embodiment. 3 shows a configuration example of a display device according to an embodiment. 4 illustrates a configuration example of an electronic device according to an embodiment. 4 illustrates a configuration example of an electronic device according to an embodiment.

  Embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it is easily understood by those skilled in the art that modes and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments below.

  Note that in structures of the invention described below, the same portions or portions having similar functions are denoted by the same reference numerals in different drawings, and description thereof is not repeated. In addition, in the case where the same function is indicated, the hatch pattern is the same, and there is a case where no reference numeral is given.

  Note that in each drawing described in this specification, the size, the layer thickness, or the region of each component is exaggerated for simplicity in some cases. Therefore, it is not necessarily limited to the scale.

  In the present specification and the like, ordinal numbers such as “first” and “second” are used for avoiding confusion between components, and are not limited numerically.

  A transistor is a kind of semiconductor element, and can realize amplification of current and voltage, switching operation for controlling conduction or non-conduction, and the like. The transistor in this specification includes an IGFET (Insulated Gate Field Effect Transistor) and a thin film transistor (TFT: Thin Film Transistor).

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

  According to one embodiment of the present invention, a first display surface that displays an image using reflected light, and a second display surface that is positioned on the opposite side of the first display surface and displays an image using light emission. A display device having a display surface. The display device can display an image on each of the first display surface and the second display surface. It can also be said that the first display surface and the second display surface are located back to back.

  For example, the display device can include a first display element that reflects visible light on the first display surface side and a second display element that emits visible light on the second display surface side. .

  In addition, the display device controls the first pixel that expresses gradation by controlling the amount of reflected light from the first display element, and the gradation by controlling the amount of light emitted from the second display element. A structure including the second pixel to be expressed is preferable. At this time, a plurality of first pixels are arranged in a matrix to form a first display portion. A plurality of second pixels are arranged in a matrix to form a second display portion.

  Here, the first display element and the second display element are preferably located on opposite sides of the insulating layer. In other words, it is preferable that the first display element is provided closer to the first display surface than the insulating layer, and the second display element be provided closer to the second display surface than the insulating layer. Thereby, the thickness of the display device can be reduced.

  By arranging the first display element and the second display element at the same pitch, the first display unit and the second display unit can have the same definition. Further, by arranging them at different pitches, the first display unit and the second display unit can have different definition.

  In the case where the first display unit and the second display unit have different definition, one of the first display element or the second display element is arranged at a low density, and the other is arranged at a high density. can do. In particular, it is preferable to arrange the first display elements at a low density and the second display elements at a high density. That is, it is preferable that the second display unit has a higher definition than the first display unit.

  As the first display element included in the first pixel, an element that reflects external light for display can be used. Since such an element does not have a light source, power consumption during display can be extremely reduced.

  As the first display element, a reflective liquid crystal element can be typically used. Alternatively, as a first display element, in addition to a shutter-type MEMS (Micro Electro Mechanical System) element, an optical interference-type MEMS element, a microcapsule type, an electrophoretic method, an electrowetting method, and an electronic powder fluid (registered trademark) An element to which a method or the like is applied can be used.

  In addition, the second display element included in the second pixel includes a light source, and an element that performs display using light from the light source can be used. In particular, an electroluminescent element that can extract light emitted from a light-emitting substance by applying an electric field is preferably used. The light emitted from such a pixel is not affected by the brightness or chromaticity of the light, and therefore has high color reproducibility (wide color gamut) and high contrast, that is, vivid display. be able to.

  As the second display element, for example, a self-luminous light emitting element such as an OLED (Organic Light Emitting Diode), an LED (Light Emitting Diode), a QLED (Quantum-Dot Light Emitting Diode), or a semiconductor laser can be used. Alternatively, as the second display element included in the second pixel, a combination of a backlight that is a light source and a transmissive liquid crystal element that controls the amount of transmitted light from the backlight may be used. .

  The first pixel can include a sub-pixel that exhibits, for example, white (W), or a sub-pixel that exhibits three colors of light, for example, red (R), green (G), and blue (B). . Similarly, the second pixel has a sub-pixel that exhibits, for example, white (W), or a sub-pixel that exhibits light of three colors, for example, red (R), green (G), and blue (B). can do. Note that the subpixels included in each of the first pixel and the second pixel may have four or more colors. As the number of subpixels increases, power consumption can be reduced and color reproducibility can be improved.

  One embodiment of the present invention is a first mode in which an image is displayed with a first pixel on the first display surface side, a second mode in which an image is displayed with a second pixel on the second display surface side, and The third mode in which an image is displayed with the first pixel and the second pixel on both the first display surface side and the second display surface side can be switched.

  The first mode is a mode in which an image is displayed using reflected light from the first display element. The first mode is a driving mode with extremely low power consumption because no light source is required. For example, it is effective when the illuminance of outside light is sufficiently high and the outside light is white light or light in the vicinity thereof. The first mode is a display mode suitable for displaying character information such as books and documents. In addition, since the reflected light is used, it is possible to perform display that is kind to the eyes, and the effect that the eyes are less tired is achieved.

  In the second mode, an image is displayed using light emitted from the second display element. Therefore, an extremely vivid display (high contrast and high color reproducibility) can be performed regardless of the illuminance and chromaticity of external light. For example, it is effective when the illuminance of outside light is extremely small, such as at night or in a dark room. Further, when the outside light is dark, the user may feel dazzled when performing bright display. In order to prevent this, it is preferable to perform display with reduced luminance in the second mode. Thereby, in addition to suppressing glare, power consumption can also be reduced. The second mode is a mode suitable for displaying a vivid image or a smooth moving image.

  The third mode is a mode in which display is performed on different display surface sides using both the reflected light from the first display element and the light emission from the second display element. Thereby, the same image or a different image can be displayed on the user and the person located on the opposite side of the user. Thereby, the usage method of the electronic device to which the display device is applied can be made more diverse. For example, it can be suitably used for an application such as a battle game. At this time, it is possible to present different images to the user and the opponent with a single electronic device.

  In the display device, the first pixel includes a first transistor electrically connected to the first display element, and the second pixel is electrically connected to the second display element. It is preferable to have a second transistor.

  At this time, it is preferable that the first transistor and the second transistor are formed on the same surface. At this time, either the first display element or the second display element is preferably electrically connected to the first transistor or the second transistor through an opening provided in the insulating layer. . Accordingly, since the first transistor and the second transistor can be manufactured in the same process, the process can be simplified.

  Here, the display device can have a structure in which, for example, a first display element, each transistor, and a second display element are sandwiched between a pair of substrates. At this time, each surface of the pair of substrates can be a first display surface or a second display surface. Images can be simultaneously displayed on the first display surface and the second display surface, or images can be displayed on only one of them.

  In addition, by adopting a structure in which the first display element, the second display element, and each transistor are sandwiched between a pair of substrates, a thin and lightweight display device can be realized.

  Hereinafter, a more specific structure example of one embodiment of the present invention will be described with reference to the drawings.

[Configuration example of display device]
FIG. 1A shows a block diagram of the display device 10. The display device 10 includes a display unit 14.

  The display unit includes a plurality of pixel units 30 arranged in a matrix. The pixel unit 30 includes a first pixel 31p and a second pixel 32p.

  Here, an example is shown in which one pixel unit 30, one first pixel 31p, and one second pixel 32p are provided. Therefore, the first pixel 31p and the second pixel 32p are arranged in a matrix at the same pitch. Note that the present invention is not limited to this, and the first pixel 31p and the second pixel 32p included in one pixel unit 30 may be independently or one or more.

  FIG. 1A shows an example in which the first pixel 31p and the second pixel 32p each have a display element corresponding to three colors of red (R), green (G), and blue (B). ing.

  The first pixel 31p includes a display element 31R corresponding to red (R), a display element 31G corresponding to green (G), and a display element 31B corresponding to blue (B). Each of the display elements 31R, 31G, and 31B is a display element that utilizes reflection of external light.

  The second pixel 32p includes a display element 32R corresponding to red (R), a display element 32G corresponding to green (G), and a display element 32B corresponding to blue (B). The display elements 32R, 32G, and 32B are display elements that use light emission.

[Configuration example of pixel unit]
FIG. 1B is a schematic diagram illustrating a configuration example of the pixel unit 30. A pixel unit 30 illustrated in FIG. 1B includes a first pixel 31 p and a second pixel 32 p between the first display surface 11 and the second display surface 12.

  The display element 31R, the display element 31G, and the display element 31B included in the first pixel 31p are elements that reflect and display external light. The display element 31R reflects external light and emits red light Rr to the display surface 11 side. Similarly, the display element 31G and the display element 31B respectively emit green light Gr or blue light Br to the display surface 11 side.

  By mixing the light (light Rr, light Gr, and light Br) from the first pixel 31p, light 35r of a predetermined color combined with reflected light can be emitted to the first display surface 11 side. . Thereby, driving with extremely low power consumption can be performed. In addition, display that is kind to the eyes can be performed. It is particularly suitable when the illuminance of outside light is sufficiently high.

  The display element 32R, the display element 32G, and the display element 32B included in the second pixel 32p are light emitting elements. The display element 32R emits red light Re to the display surface 12 side. Similarly, the display element 32G and the display element 32B respectively emit green light Ge or blue light Be to the display surface 12 side.

  By mixing the light (light Re, light Ge, and light Be) from the second pixel 32p, light 35e of a predetermined color can be emitted to the second display surface 12 side. Thereby, a vivid display can be performed. Further, when the illuminance of outside light is small, by reducing the luminance, it is possible to suppress glare that the user feels and to reduce power consumption.

  It is preferable that the first pixel 31p and the second pixel 32p can be driven individually. That is, it is preferable that the image can be displayed using the first pixel 31p and the image can be displayed independently using the second pixel 32p. Accordingly, the first mode in which an image is displayed on the first display surface 11 by the first pixel 31p, the second mode in which an image is displayed on the second display surface 12 by the second pixel 32p, The third mode in which an image is displayed on both the first display surface 11 and the second display surface 12 can be switched by the one pixel 31p and the second pixel 32p.

[Modification]
In the above example, the first pixel 31p and the second pixel 32p each have a display element corresponding to three colors of red (R), green (G), and blue (B). Not limited. Below, the example of a structure different from the above is shown.

  2A to 2C and FIGS. 3A to 3C show configuration examples of pixel units, respectively.

  FIG. 2A illustrates an example in which the second pixel 32p includes a display element 32W that exhibits white (W) in addition to the display element 32R, the display element 32G, and the display element 32B. Thereby, the power consumption in the display mode (the second mode and the third mode) using the second pixel 32p can be reduced.

  FIG. 2B illustrates an example in which the first pixel 31p includes a display element 31W that exhibits white (W) in addition to the display element 31R, the display element 31G, and the display element 31B. Thereby, power consumption in the display mode (the first mode and the third mode) using the first pixel 31p can be reduced.

  FIG. 2C illustrates an example in which the first pixel 31p includes a display element 31W that exhibits white (W) in addition to the display element 31R, the display element 31G, and the display element 31B. Further, FIG. 2C illustrates an example in which the second pixel 32p includes a display element 32W that exhibits white (W) in addition to the display element 32R, the display element 32G, and the display element 32B. Accordingly, power consumption in the display mode (first mode and third mode) using the first pixel 31p and the display mode (second mode and third mode) using the second pixel 32p. Can be reduced.

  2A to 2C, a display element exhibiting yellow (Y) may be used instead of the display element 31W or the display element 32W. Alternatively, in addition to the display element 31 </ b> W or the display element 32 </ b> W, a structure having a display element that exhibits yellow (Y) may be used. Thereby, power consumption in each display mode using the first pixel 31p or the second pixel 32p can be reduced.

  FIG. 3A illustrates an example in which the first pixel 31p includes only the display element 31W that exhibits white. At this time, in the display using the first pixel 31p, monochrome display or grayscale display can be performed, and in the display using the second pixel 32p, color display can be performed.

  Further, with such a configuration, the aperture ratio of the first pixel 31p can be increased, so that the reflectance of the first pixel 31p can be improved and brighter display can be performed.

  In the case where the display is performed by the first pixel 31p, for example, it is suitable for displaying information that does not require color display such as document information. When displaying with the first pixel 31p, an electronic device incorporating the display device can be used, for example, like an electronic book terminal or a textbook.

  3B and 3C show an example in which the first pixel 31p and the second pixel 32p are arranged with different resolutions.

  FIG. 3B illustrates an example in which two second pixels 32p are provided for one first pixel 31p. That is, an example in which the definition of the second pixel 32p is twice the definition of the first pixel 31p is shown. Thereby, the image displayed by the 2nd pixel 32p can be made into a higher definition. In addition, the image displayed by the second pixel 32p can have a higher resolution.

  FIG. 3C illustrates an example in which three second pixels 32p are provided for one first pixel 31p. That is, an example is shown in which the definition of the second pixel 32p is three times the definition of the first pixel 31p. Thereby, the image displayed by the 2nd pixel 32p can be made into a higher definition. In addition, the image displayed by the second pixel 32p can have a higher resolution.

  In this way, by making the first pixels 31p and the second pixels 32p different in definition, it is possible to achieve a definition suitable for an image displayed by each pixel. For example, the first pixel 31p can mainly display character information and the like, and the second pixel 32p can display a still image or a moving image.

  Since one embodiment of the present invention includes two display surfaces positioned back to back, it is possible to select different resolutions or select different color display methods depending on the application. It becomes possible to widen the width.

  The above is the description of the display unit.

[Section configuration example]
FIG. 4 shows an example of a cross-sectional configuration of the display device 10.

  The display device 10 includes a functional layer 41, an insulating layer 81, an insulating layer 83, a display element 90, a display element 40, and the like between the substrate 31 and the substrate 32. The surface located outside the substrate 31 corresponds to the display surface 11, and the surface located outside the substrate 21 corresponds to the display surface 12.

  The display element 40 includes a conductive layer 23, a conductive layer 25, and a liquid crystal 24 sandwiched therebetween. The conductive layer 23 reflects visible light, and the conductive layer 25 transmits visible light. Accordingly, the display element 40 is a reflective liquid crystal element that emits the reflected light 20b toward the substrate 31 side. Here, the conductive layer 23 is disposed for each pixel (for each sub-pixel) and functions as a pixel electrode. The conductive layer 25 is disposed over a plurality of pixels. The conductive layer 25 is connected to a wiring to which a constant potential is supplied in a region not shown, and functions as a common electrode.

  The display element 90 includes a conductive layer 91, a conductive layer 93, and an EL layer 92 sandwiched therebetween. The EL layer 92 is a layer containing at least a light-emitting substance. The conductive layer 91 reflects visible light, and the conductive layer 93 transmits visible light. Therefore, the display element 90 is an electroluminescent element that emits light emission 20 a to the substrate 21 side by applying a voltage between the conductive layer 91 and the conductive layer 93. The conductive layer 91 is disposed for each pixel (each subpixel) and functions as a pixel electrode. The conductive layer 93 is disposed over a plurality of pixels. The conductive layer 93 is connected to a wiring to which a constant potential is supplied in a region not shown, and functions as a common electrode.

  The functional layer 41 is a layer including a circuit that drives the display element 40 and a circuit that drives the display element 90. For example, in the functional layer 41, a pixel circuit is configured by a transistor, a capacitor, a wiring, an electrode, and the like.

  An insulating layer 83 is provided between the functional layer 41 and the conductive layer 23. The conductive layer 23 and the functional layer 41 are electrically connected through an opening provided in the insulating layer 83. Thereby, the functional layer 41 and the display element 40 are electrically connected.

  An insulating layer 81 is provided between the functional layer 41 and the conductive layer 91. The conductive layer 91 and the functional layer 41 are electrically connected through an opening provided in the insulating layer 81. Thereby, the functional layer 41 and the display element 90 are electrically connected.

  An insulating layer 84 is provided so as to cover an end portion of the conductive layer 91, and an EL layer 92 is provided so as to cover a part of the insulating layer 84 and a part of the conductive layer 91. A conductive layer 93 is provided so as to cover part of the EL layer 92 and the insulating layer 84.

  An adhesive layer 89 is provided between the substrate 21 and the conductive layer 93. It can be said that the substrate 21 and the substrate 31 are bonded together by the adhesive layer 89. The adhesive layer 89 also functions as a sealing layer that seals the display element 90.

  Thus, the configuration can be simplified by disposing the functional layer 41 that drives each of the two types of display elements (the display element 40 and the display element 90) between the display element 40 and the display element 90. In addition, since manufacturing steps of a transistor and the like can be made common, manufacturing cost can be reduced.

  Here, in the case where a metal oxide is applied to the pixel circuit of the functional layer 41 and a transistor with extremely low off-state current is applied, or when a memory element is applied to the pixel circuit, the display element 40 or the display element 90 Even when the writing operation to the pixel is stopped when displaying a still image using the, gradation can be maintained. That is, display can be maintained even if the frame rate is extremely small. Therefore, the frame rate can be extremely reduced while maintaining display quality, and driving with low power consumption can be performed.

  Although not shown here, it is preferable to provide a polarizing plate between the conductive layer 25 and the display surface 11. It is particularly preferable to use a circularly polarizing plate. As a circularly-polarizing plate, what laminated | stacked the linearly-polarizing plate and the quarter wavelength phase difference plate, for example can be used. Thereby, external light reflection can be suppressed. The polarizing plate can be disposed on the outer surface of the substrate 31. At this time, the display surface 11 is positioned on the outer side of the polarizing plate.

  Various optical members can be arranged outside the substrate 31. Examples of the optical member include the polarizing plate and the retardation plate, a light diffusing layer (such as a diffusing film), an antireflection layer, and a light collecting film. Further, on the outside of the substrate 31, an antistatic film that suppresses the adhesion of dust, a water-repellent film that makes it difficult to adhere dirt, a hard coat film that suppresses the occurrence of scratches due to use, and the like may be disposed. Also, the optical member can be provided outside the substrate 21. When the optical member is provided outside the substrate 31 or outside the substrate 21, the display surface 11 or the display surface 12 is positioned outside the optical member.

  The above is the description of the cross-sectional configuration example.

  This embodiment can be implemented in appropriate combination with at least part of the other embodiments described in this specification.

(Embodiment 2)
Hereinafter, a more specific structure example and a manufacturing method example of one embodiment of the present invention will be described.

  Hereinafter, as an example of a display device of one embodiment of the present invention, a display device (display panel) that includes both a reflective liquid crystal element and a light-emitting element and can display in both a transmissive mode and a reflective mode. ) Will be described. Such a display panel can also be referred to as TR-Hybrid Display (Transmissive OLED and Reflective LC Hybrid Display).

  As an example of such a display panel, there is a configuration in which a liquid crystal element including an electrode that reflects visible light and a light emitting element are stacked. At this time, it is preferable that the liquid crystal element and the light emitting element are arranged to overlap each other. By stacking these layers, a higher-definition display device can be realized as compared with the case where the liquid crystal elements and the light-emitting elements are arranged side by side in a plan view.

  Furthermore, it is preferable that the transistor for driving the liquid crystal element and the transistor for forming the light emitting element are arranged on the same plane. In addition, the light-emitting element and the liquid crystal element are preferably stacked with an insulating layer interposed therebetween.

  Such a display panel can be driven with extremely low power consumption by displaying with a reflective element in a bright place such as outdoors. Further, in a place where the outside light is dark such as at night or indoors, an image can be displayed with an optimum luminance by displaying with a light emitting element.

[Configuration example of display device]
5A and 5B are perspective schematic views of the display device 10 of one embodiment of the present invention. 5A is a perspective view showing the display unit 14a side of the display device 10, and FIG. 5B is a perspective view showing the display unit 14b side when FIG. 5A is viewed from the back side. It is. The display device 10 has a configuration in which a substrate 21 and a substrate 31 are bonded together. 5A and 5B, the substrate 31 is clearly indicated by a broken line.

  The display device 10 includes a display unit 14a, a display unit 14b, a circuit 34, a wiring 35, and the like. 5A and 5B show an example in which the IC 37 and the FPC 36 are mounted on the substrate 21. FIG. Therefore, the structure illustrated in FIGS. 5A and 5B can also be referred to as a display module.

  As the circuit 34, for example, a circuit that functions as a scan line driver circuit can be used.

  The wiring 35 has a function of supplying signals and power to the display unit 14a, the display unit 14b, the circuit 34, and the like. The signal and power are input to the wiring 35 from the outside via the FPC 36 or from the IC 37.

  5A and 5B illustrate an example in which the IC 37 is mounted on the substrate 21 by a COG (Chip On Glass) method or the like. For example, an IC having a function as a signal line driver circuit or the like can be applied to the IC 37. When the display device 10 includes a circuit that functions as a signal line driver circuit, or when a circuit that functions as a signal line driver circuit is provided outside and a signal for driving the display device 10 is input via the FPC 36, etc. The IC 37 may not be provided. Further, the IC 37 may be mounted on the FPC 36 by a COF (Chip On Film) method or the like.

  The display unit 14a and the display unit 14b are positioned back to back. For example, the display unit 14a is a region that displays an image using reflected light, and the display unit 14b is a region that displays an image using light emitted from the element.

[Cross-section configuration example 1]
FIG. 6 is a schematic cross-sectional view of a display device exemplified below. In the configuration shown in FIG. 6, the display element 40 and the display element 90 are arranged so as to overlap each other with an insulating layer 83 interposed therebetween. In the configuration shown in FIG. 6, the surface on the substrate 31 side corresponds to the first display surface 11, and the surface on the substrate 21 side corresponds to the display surface 12.

  The display device includes a transistor 70 a and a transistor 70 b formed on one surface of the insulating layer 83. The transistor 70 a is electrically connected to the display element 40, and the transistor 70 b is electrically connected to the display element 90.

  A conductive layer 91 is provided on the substrate 21 side of the insulating layer 81 covering the transistors 70 a and 70 b, and an insulating layer 84 is provided so as to cover an end portion of the conductive layer 91. The conductive layer 91 and one of the source and the drain of the transistor 70 b are electrically connected through an opening provided in the insulating layer 81. The insulating layer 81 functions as a planarization layer. An EL layer 92 and a conductive layer 93 are provided on the substrate 21 side of the insulating layer 81. A display element 90 is configured by the conductive layer 91, the EL layer 92, and the conductive layer 93.

  The conductive layer 91 has a function of reflecting visible light. The conductive layer 93 has a function of transmitting visible light. Therefore, the display element 90 is a top emission type (also referred to as top emission type) light emitting element that emits light to the conductive layer 93 side.

  The substrate 21 is provided with a colored layer 52a (or a colored layer 52b) at a position overlapping the display element 90.

  In FIG. 6, the EL layer 92 is provided between adjacent pixels. Therefore, each of the plurality of display elements 90 is a light emitting element that emits light of the same color. Preferably, the light emitting element emits white light. The light emitted from the display element 90 shown in FIG. 6 is colored by passing through the colored layer 52a and the like, and is emitted to the display surface 12 side.

  FIG. 6 shows an example in which an insulating layer 94 that covers the conductive layer 93 is provided. The insulating layer 94 has a function as a barrier film that prevents impurities such as water from diffusing into the display element 90.

  The conductive layer 23 is provided on the substrate 31 side of the insulating layer 83, and an alignment film 53 a is provided so as to cover the conductive layer 23. A colored layer 51a, a colored layer 51b, and a light shielding layer 52 are provided on the substrate 21 side of the substrate 31, and an insulating layer 61 is provided so as to cover them. A conductive layer 25 and an alignment film 53b are stacked on the substrate 21 side of the insulating layer 61. The liquid crystal 24 is sandwiched between the alignment film 53a and the alignment film 53b. The display element 40 is configured by the conductive layer 23, the liquid crystal 24, and the conductive layer 25.

  In addition, the display device includes a connection portion 80 that electrically connects conductive layers provided on both surfaces of the insulating layer 83. In FIG. 6, the connection portion 80 includes an opening provided in the insulating layer 83 and a conductive layer that is located in the opening and is obtained by processing the same conductive film as the gate of the transistor 70 a or the like. Show. One of a source and a drain of the transistor 70 a and the conductive layer 23 b are electrically connected through a connection portion 80.

  The conductive layer 23 has a function of reflecting visible light. The conductive layer 25 has a function of transmitting visible light. Therefore, the display element 40 functions as a reflective liquid crystal element that reflects light toward the first display surface 11 side.

  Since the display device illustrated in FIG. 6 includes the transistor 70a electrically connected to the display element 40 and the transistor 70b electrically connected to the display element 90, the display element 40 and the display element 90 can be controlled independently. Is possible. Further, since the transistor 70a and the transistor 70b can be formed over the same surface through the same process, the process is simplified and the transistor 70a and the transistor 70b can be manufactured with high yield.

  Further, as shown in FIG. 6, the conductive layer 23 functioning as the pixel electrode of the display element 40 has no step or unevenness on the surface on the liquid crystal 24 side between the region overlapping with the connection portion 80 and the region not overlapping. It has a configuration. For this reason, the display element 40 can be used as a display region because the alignment of the liquid crystal 24 does not occur even in the portion overlapping the connection portion 80.

  On the other hand, a part of the conductive layer 91 functioning as a pixel electrode of the display element 90 is formed with a recess at a connection portion with the transistor 70b. Therefore, it is preferable that this portion is covered with the insulating layer 84 and not used as a display region.

  Thus, since the display element 40 can use the contact portion between the pixel electrode and the transistor as a display area, the area of the display area of the display element 40 is made larger than the area of the display area of the display element 90. Can do. Alternatively, the aperture ratio on the display surface 11 side can be made larger than the aperture ratio on the display surface 12 side.

  Here, in this specification and the like, the aperture ratio includes the area of the light emitting region in the display region (effective light emitting region or effective light emitting area) or the ratio of the area of the light emitting region in the display region (effective light emitting area ratio). .

  Although not shown here, a polarizing plate, preferably a circular polarizing plate is preferably provided outside the substrate 31. Furthermore, you may provide optical members, such as a light-diffusion layer (a diffusion film etc.), an antireflection layer, and a condensing film. At this time, the display surface 11 is located outside the polarizing plate, the circularly polarizing plate, or various optical members. Moreover, you may provide a circularly-polarizing plate and an optical member in the outer side of the board | substrate 21, and the display surface 12 is located outside the said circularly-polarizing plate and an optical member at this time.

[Modification 1]
FIG. 7 illustrates a configuration example of a display device that is partly different from the configuration illustrated in FIG. In FIG. 7, the configuration of the display element 90 is mainly different from the configuration illustrated in FIG. 6.

  The display element 90 shows an example in which an EL layer is separately formed for each adjacent display element 90. FIG. 6 shows an EL layer 92a and an EL layer 92b. The display element 90 having the EL layer 92a and the display element 90 having the EL layer 92b each emit light of different colors.

  By using such a display element 90, the colored layer 52a and the like are unnecessary, so that the configuration of the substrate 21 can be simplified.

[Modification 2]
FIGS. 8A and 8B illustrate configuration examples of display devices that are partly different from the configurations illustrated in FIGS. 6 and 7, respectively.

  8A and 8B include a substrate 41a instead of the substrate 21 and a substrate 41b instead of the substrate 31 in the configuration illustrated in FIG. 6 or FIG.

  A thin and light material can be used for the substrate 41a and the substrate 41b. Preferably, a flexible material can be used for the substrate 41b. Further, a flexible display device can be realized by using a flexible material for both the substrate 41b and the substrate 41a.

  For example, as the substrate 41a and the substrate 41b, a thin sheet material having a thickness of 1 μm to 300 μm, preferably 3 μm to 200 μm, more preferably 5 μm to 150 μm, and further preferably 10 μm to 100 μm can be used. .

  The above is the description of the modified example.

  Note that one embodiment of the present invention is not limited to the structure described above. For example, a display panel to which a display element that reflects visible light is applied and a display panel to which a display element that emits visible light is applied may be bonded back to back.

[Example of production method]
Hereinafter, an example of a method for manufacturing the display device illustrated in FIGS.

  Note that a thin film (an insulating film, a semiconductor film, a conductive film, or the like) included in the display device can be formed using a sputtering method, a chemical vapor deposition (CVD) method, a vacuum evaporation method, or a pulse laser deposition (PLD: Pulse Laser Deposition). ) Method, atomic layer deposition (ALD: Atomic Layer Deposition) method, or the like. The CVD method may be a plasma enhanced chemical vapor deposition (PECVD) method or a thermal CVD method. As an example of the thermal CVD method, a metal organic chemical vapor deposition (MOCVD) method may be used.

  Thin films (insulating films, semiconductor films, conductive films, etc.) that constitute display devices are spin coat, dip, spray coating, ink jet, dispense, screen printing, offset printing, doctor knife, slit coat, roll coat, curtain coat. It can be formed by a method such as knife coating.

  Further, when a thin film included in the display device is processed, the thin film can be processed using a photolithography method or the like. Alternatively, an island-shaped thin film may be formed by a film formation method using a shielding mask. Alternatively, the thin film may be processed by a nanoimprint method, a sand blast method, a lift-off method, or the like. As a photolithography method, a resist mask is formed on a thin film to be processed, the thin film is processed by etching or the like, and the resist mask is removed. After forming a photosensitive thin film, exposure and development are performed. And a method for processing the thin film into a desired shape.

  In photolithography, light used for exposure can be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or light obtained by mixing these. In addition, ultraviolet light, KrF laser light, ArF laser light, or the like can be used. Further, exposure may be performed by an immersion exposure technique. Further, extreme ultraviolet light (EUV: Extreme Ultra-violet) or X-rays may be used as light used for exposure. Further, an electron beam can be used instead of the light used for exposure. It is preferable to use extreme ultraviolet light, X-rays, or an electron beam because extremely fine processing is possible. Note that a photomask is not necessary when exposure is performed by scanning a beam such as an electron beam.

  For etching the thin film, a dry etching method, a wet etching method, a sand blasting method, or the like can be used.

  First, the separation layer 43 and the insulating layer 45 are stacked over the supporting substrate 44 (10 (A)).

  As the support substrate 44, a substrate that is rigid to such an extent that it can be easily transported within the apparatus or between apparatuses can be used. In addition, a substrate having heat resistance to heat applied in the manufacturing process is used. For example, a glass substrate having a thickness of 0.3 mm to 1 mm can be used.

  As a material used for the peeling layer 43 and the insulating layer 45, a material that causes peeling at the interface between the peeling layer 43 and the insulating layer 45, in the insulating layer 45, or in the peeling layer 43 can be selected.

  For example, a layer containing a refractory metal material such as tungsten and a layer containing an oxide of the metal material are stacked as the separation layer 43, and silicon nitride, silicon oxide, silicon oxynitride, or oxynitride is used as the insulating layer 45. A layer of an inorganic insulating material such as silicon can be stacked. Note that in this specification, oxynitride refers to a material having a higher oxygen content than nitrogen as its composition, and nitride oxide refers to a material having a higher nitrogen content than oxygen as its composition. Point to. It is preferable to use a refractory metal material for the peeling layer 43 because processing at a high temperature is possible in the subsequent steps, and the degree of freedom in selecting a material and a forming method is increased.

  In the case where a stacked structure of tungsten and tungsten oxide is used as the separation layer 43, separation can be performed at the interface between tungsten and tungsten oxide, in tungsten oxide, or at the interface between tungsten oxide and the insulating layer 45.

  Subsequently, the conductive layer 23 is formed over the insulating layer 45 (FIG. 9B). As the conductive layer 23, a single layer structure including a metal or an alloy material, or a stacked structure can be used. In the case of using a laminated structure as the conductive layer 23, it is preferable to use a material having high reflectance for the layer provided on the upper side.

  Here, the conductive layer 23 may have a stacked structure, a metal oxide film may be applied to the support substrate 44 side, and a conductive film that reflects visible light may be applied thereon. At this time, in the case where peeling between the metal oxide film and the peeling layer 43 is possible, the insulating layer 45 may not be provided.

  For example, in the case where a metal oxide (also referred to as metal oxide) film having semiconductor characteristics is used below the conductive layer 23, oxygen vacancies are generated in the metal oxide film by plasma treatment, heat treatment, or the like. The carrier density may be increased. The carrier density may be increased by introducing impurities such as rare gas such as argon in addition to hydrogen and nitrogen into the metal oxide film. Alternatively, the conductive film used for the upper side of the conductive layer 23 may be formed using a material in which oxygen is easily diffused, whereby oxygen in the metal oxide film may be reduced. Two or more methods described above may be applied.

  Subsequently, an insulating layer 83 is formed so as to cover the insulating layer 45 and the conductive layer 23. At this time, an opening reaching the conductive layer 23 is formed in part of the insulating layer 83 (FIG. 9C).

  Subsequently, the transistor 70a and the transistor 70b are formed. At the same time, the connection portion 80 is formed (FIG. 9D).

  First, the conductive layer 71 is formed over the insulating layer 83. The conductive layer 71 can be formed by forming a conductive film, forming a resist mask, etching the conductive film, and then removing the resist mask.

  Subsequently, an insulating layer 82 is formed.

  Subsequently, the semiconductor layer 72 is formed. The semiconductor layer 72 can be formed by forming a semiconductor film, forming a resist mask, etching the semiconductor film, and then removing the resist mask.

  Subsequently, a conductive layer 74a and a conductive layer 74b are formed. The conductive layer 74 a and the conductive layer 74 b can be formed by a method similar to that of the conductive layer 71.

  Through the above steps, the transistor 70a and the transistor 70b can be formed. Part of the conductive layer 71 functions as the gate of the transistor, part of the insulating layer 81 functions as the gate insulating layer of the transistor, and part of the semiconductor layer 72 has a region where the channel of the transistor is formed. The conductive layer 74a functions as one of a source and a drain of the transistor and functions as the other of the source and the drain of the conductive layer 74b.

  At this time, in the step of forming the gates of the transistors 70a and 70b, the conductive layer electrically connected to the conductive layer 23 through the opening provided in the insulating layer 83 when the conductive film is processed after the conductive film is formed. Are formed at the same time. Thereby, the connection part 80 can be formed.

  In addition, an opening is preferably formed in an insulating layer functioning as a gate insulating layer of the transistor 70a or the like so that one of the source and the drain of the transistor 70a is electrically connected to the connection portion 80.

  Subsequently, an insulating layer 81 covering the transistors 70a and 70b is formed. At this time, the insulating layer 81 forms an opening reaching one of the source and the drain of the transistor 70b. By using a photosensitive material for the insulating layer 81, an opening can be formed by a photolithography method or the like. Note that the opening may be formed by a photolithography method or the like after the insulating layer 81 is formed. It is preferable to use an organic insulating material for the insulating layer 81 because the flatness of the upper surface can be improved. The insulating layer 81 may have a stacked structure of an inorganic insulating film and an organic insulating film.

  After that, a conductive layer 91 is formed over the insulating layer 81 (FIG. 9E). The conductive layer 91 is provided so as to cover the opening provided in the insulating layer 81, so that it is electrically connected to one of the source and the drain of the transistor 70b.

  Subsequently, an insulating layer 84 that covers an end portion of the conductive layer 91 and has an opening in a portion overlapping the conductive layer 91 is formed. The insulating layer 84 covers the end portion of the conductive layer 91 and functions as a planarization layer. As the insulating layer 84, an organic resin is preferably used. The insulating layer 84 preferably has a tapered end portion.

  Subsequently, an EL layer 92 and a conductive layer 93 are formed in this order over the conductive layer 91 and the insulating layer 84. The EL layer 92 and the conductive layer 93 can be formed by, for example, a vacuum evaporation method.

  Subsequently, an insulating layer 94 is formed over the conductive layer 93 (FIG. 10A). For the insulating layer 94, it is preferable to use a film formation method such as a sputtering method or an ALD method, which can form a dense film even when the formation temperature is lowered. Alternatively, a stacked structure of a film including an inorganic insulating material and a film including an organic insulating material may be employed.

  Through the above steps, the transistor 70a, the transistor 70b, and the display element 90 can be formed over the supporting substrate 44.

  Subsequently, a colored layer 52a, a colored layer 52b, and the like are formed over the substrate 21 (FIG. 10B). The colored layer 52a and the like can be formed by a photolithography method using a photosensitive material, for example.

  A light shielding layer may be formed on the substrate 21 in addition to the colored layer 52a and the like.

  The process on the substrate 21 side and the process on the support substrate 44 side can be performed independently, and the order thereof is not limited.

  Subsequently, the insulating layer 94 and the substrate 21 are bonded to each other through the adhesive layer 89 (FIG. 10C).

  Subsequently, the support substrate 44 and the release layer 43 are removed by peeling between the release layer 43 and the insulating layer 45 (FIG. 11A).

  The peeling layer 43 and the insulating layer 45 can be peeled off by applying mechanical force, etching the peeling layer 43, dropping a liquid, or impregnating the liquid, etc. As an example, it is permeated. Alternatively, peeling may be performed by heating or cooling using a difference in thermal expansion between the two layers forming the peeling interface.

  Moreover, you may perform the process which exposes a part of peeling interface before peeling. For example, a part of the insulating layer 45 on the peeling layer 43 is removed by a laser or a sharp member. As a result, the peeling can be progressed starting from the portion from which the insulating layer 45 is removed as the starting point (starting point).

  After the peeling is finished, a part of the peeling layer 43 may remain on the surface of the insulating layer 45 in some cases. In that case, the remaining peeling layer 43 may be removed by washing, etching, wiping, or the like.

  Subsequently, it is preferable to remove the insulating layer 45. The insulating layer 45 can be formed using a wet etching method, a dry etching method, or an etching method combining these. The insulating layer 45 may not be removed if it is not necessary to remove it. A schematic cross-sectional view at the stage where the insulating layer 45 is removed corresponds to FIG.

  Note that when the insulating layer 45 is etched, part of the surface of the conductive layer 23 or part of the surface of the insulating layer 83 may be etched. In that case, the height of the surface of the conductive layer 23 and the height of the surface of the insulating layer 83 do not coincide with each other, and there may be a step at the boundary between these.

  After that, an alignment film 53a is formed over the conductive layer 23 and the insulating layer 83 (FIG. 11C). The alignment film 53a can be formed by performing a rubbing process after forming a thin film to be the alignment film 53a.

  Subsequently, the substrate 31 is prepared, and the light shielding layer 52 is formed on the substrate 31. The light shielding layer 52 may be formed by processing the conductive film and using the same method as the conductive layer 71 or the like, or using a metal material, a resin material containing a pigment or a dye, and the same method as the insulating layer 81 or the like. May be formed.

  Subsequently, a colored layer 51a, a colored layer 51b, and the like are formed. The colored layer 51a and the colored layer 51b can be formed by a method similar to that for the colored layer 52a and the like.

  Note that the colored layer 51 a and the colored layer 51 b may be formed before the light shielding layer 52. At this time, it is preferable that a part of the light shielding layer 52 is formed so as to cover the end portions of the colored layer 51a and the colored layer 51b. Alternatively, the light shielding layer 52 may be omitted, and a region where the colored layer 51a and the colored layer 51b partially overlap each other may be provided.

  Subsequently, an insulating layer 61 is formed to cover the light shielding layer 52, the colored layer 51a, the colored layer 51b, and the like. The insulating layer 61 has a function as an overcoat which prevents impurities contained in the colored layer 51 a and the like from diffusing into the liquid crystal 24. The insulating layer 61 may have a function as a planarizing layer that covers steps on the surface of the light shielding layer 52, the colored layer 51a, the colored layer 51b, and the like. Note that the insulating layer 61 may be omitted if unnecessary.

  Subsequently, the conductive layer 25 is formed on the insulating layer 61. The conductive layer 25 can be formed by a method similar to that of the conductive layer 71 or the like. Alternatively, the island-shaped conductive layer 25 may be formed by a film formation method using a shielding mask.

  Subsequently, an alignment film 53b is formed over the conductive layer 25 (FIG. 12A). The alignment film 53b can be formed by a method similar to that of the alignment film 53a.

  Note that the above-described process on the substrate 21 side and the process on the substrate 31 side can proceed independently.

  Subsequently, an adhesive layer (not shown) for bonding them is formed on one or both of the substrate 21 and the substrate 31. The adhesive layer is formed so as to surround a region where the pixels are arranged. The adhesive layer can be formed by, for example, a screen printing method or a dispensing method. As the adhesive layer, a curable resin such as a thermosetting resin or an ultraviolet curable resin can be used. Alternatively, a resin that is cured by applying heat after being temporarily cured by ultraviolet rays may be used. Alternatively, as the adhesive layer, a resin having both ultraviolet curable properties and thermosetting properties may be used.

  Subsequently, the composition containing the liquid crystal 24 is dropped onto a region surrounded by the adhesive layer by a dispensing method or the like.

  Subsequently, the substrate 21 and the substrate 31 are bonded so as to sandwich the composition containing the liquid crystal 24, and the adhesive layer is cured. Bonding is preferably performed in a reduced-pressure atmosphere because air bubbles and the like can be prevented from being mixed between the substrate 21 and the substrate 31. Moreover, it is preferable to bond in a reduced pressure atmosphere and to cure the adhesive layer while exposed to an atmospheric pressure atmosphere.

  Note that the composition containing the liquid crystal 24 may be injected from a gap provided in the adhesive layer in a reduced-pressure atmosphere after the substrate 21 and the substrate 31 are bonded to each other. Further, after the composition containing the liquid crystal 24 is dropped, a granular gap spacer may be sprayed on the region where the pixels are arranged or outside the region, or the composition containing the gap spacer may be dropped. .

  Through the above steps, the display device 10 can be manufactured (FIG. 12B). FIG. 12B is the same diagram as FIG.

  Note that in the case of the structure shown in FIGS. 7A and 7B, the EL layer 92a and the EL layer 92b can be manufactured separately in the manufacturing process of the EL layer 92 in the above manufacturing method example. For example, the EL layer 92a or the like may be formed using a vapor deposition method using a shadow mask such as a metal mask, an inkjet method, or the like. In the case where the EL layer 92a, the EL layer 92b, and the like have a stacked structure, some layers may be used in common.

  8A and 8B, a substrate 41a and a substrate 41b can be used instead of the substrate 21 and the substrate 31 in the above manufacturing method example. In this example of the manufacturing method, a layer formed over the substrate 41a or the substrate 41b (for example, the colored layer 51a, the colored layer 52a, the conductive layer 25, or the like) does not require a high formation temperature. It is easy to use a substrate or a film containing Further, the layers formed over the substrate 41a and the substrate 41b can be formed using a roll-to-roll method, which can reduce cost.

  The above is the description of the manufacturing method example.

[About each component]
Below, each component shown above is demonstrated.

〔substrate〕
As the substrate included in the display device, a material having a flat surface can be used. For the substrate from which light from the display element is extracted, a material that transmits the light is used. For example, materials such as glass, quartz, ceramic, sapphire, and organic resin can be used.

  By using a thin substrate, the display device can be reduced in weight and thickness. Furthermore, a flexible display device can be realized by using a flexible substrate.

  Further, since the substrate on the side from which light emission is not extracted does not have to be translucent, a metal substrate or the like can be used in addition to the above-described substrates. A metal substrate is preferable because it has high thermal conductivity and can easily conduct heat to the entire substrate, which can suppress a local temperature increase of the display device. In order to obtain flexibility and bendability, the thickness of the metal substrate is preferably 10 μm to 200 μm, and more preferably 20 μm to 50 μm.

  Although there is no limitation in particular as a material which comprises a metal substrate, For example, metals, such as aluminum, copper, nickel, or alloys, such as aluminum alloy or stainless steel, can be used suitably.

  Alternatively, a substrate that has been subjected to an insulating process by oxidizing the surface of the metal substrate or forming an insulating film on the surface may be used. For example, the insulating film may be formed by using a coating method such as a spin coating method or a dip method, an electrodeposition method, a vapor deposition method, or a sputtering method, or it is left in an oxygen atmosphere or heated, or an anodic oxidation method. For example, an oxide film may be formed on the surface of the substrate.

Examples of the material having flexibility and transparency to visible light include, for example, glass having a thickness having flexibility, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), and polyacrylonitrile resin. , Polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin, cycloolefin resin, polystyrene resin, polyamideimide resin, polyvinyl chloride resin, polytetrafluoroethylene (PTFE) resin Etc. In particular, a material having a low thermal expansion coefficient is preferably used. For example, a polyamideimide resin, a polyimide resin, PET, or the like having a thermal expansion coefficient of 30 × 10 ⁻⁶ / K or less can be suitably used. Further, a substrate in which glass fiber is impregnated with an organic resin, or a substrate in which an inorganic filler is mixed with an organic resin to reduce the thermal expansion coefficient can be used. Since a substrate using such a material is light, a display device using the substrate can be light.

  When a fibrous body is included in the material, a high-strength fiber of an organic compound or an inorganic compound is used for the fibrous body. The high-strength fiber specifically refers to a fiber having a high tensile modulus or Young's modulus, and representative examples include polyvinyl alcohol fiber, polyester fiber, polyamide fiber, polyethylene fiber, aramid fiber, Examples include polyparaphenylene benzobisoxazole fibers, glass fibers, and carbon fibers. Examples of the glass fiber include glass fibers using E glass, S glass, D glass, Q glass, and the like. These may be used in the form of a woven fabric or a non-woven fabric, and a structure obtained by impregnating the fiber body with a resin and curing the resin may be used as a flexible substrate. When a structure made of a fibrous body and a resin is used as the flexible substrate, it is preferable because reliability against breakage due to bending or local pressing is improved.

  Alternatively, glass, metal, or the like thin enough to have flexibility can be used for the substrate. Alternatively, a composite material in which glass and a resin material are bonded to each other with an adhesive layer may be used.

  A hard coat layer (for example, silicon nitride, aluminum oxide) that protects the surface of the display device from scratches, a layer of a material that can disperse the pressure (for example, aramid resin), etc. on a flexible substrate It may be laminated. In order to suppress a decrease in the lifetime of the display element due to moisture or the like, an insulating film with low water permeability may be stacked over a flexible substrate. For example, an inorganic insulating material such as silicon nitride, silicon oxynitride, silicon nitride oxide, aluminum oxide, or aluminum nitride can be used.

  The substrate can be used by stacking a plurality of layers. In particular, when the glass layer is used, the barrier property against water and oxygen can be improved, and a highly reliable display device can be obtained.

[Transistor]
The transistor includes a conductive layer that functions as a gate electrode, a semiconductor layer, a conductive layer that functions as a source electrode, a conductive layer that functions as a drain electrode, and an insulating layer that functions as a gate insulating layer. The above shows the case where a bottom-gate transistor is applied.

  Note that there is no particular limitation on the structure of the transistor included in the display device of one embodiment of the present invention. For example, a planar transistor, a staggered transistor, or an inverted staggered transistor may be used. Further, a top-gate or bottom-gate transistor structure may be employed. Alternatively, gate electrodes may be provided above and below the channel.

  There is no particular limitation on the crystallinity of a semiconductor material used for the transistor, and any of an amorphous semiconductor and a semiconductor having crystallinity (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor partially including a crystal region) is used. May be used. It is preferable to use a crystalline semiconductor because deterioration of transistor characteristics can be suppressed.

  As a semiconductor material used for the transistor, for example, a Group 14 element (silicon, germanium, or the like), a compound semiconductor, or a metal oxide having semiconductor characteristics can be used for the semiconductor layer. Typically, a semiconductor containing silicon, a semiconductor containing gallium arsenide, a metal oxide containing indium, or the like can be used.

  In particular, it is preferable to use a metal oxide having a larger band gap than silicon. It is preferable to use a semiconductor material with a wider band gap and lower carrier density than silicon because current in an off state of the transistor can be reduced.

  In particular, the semiconductor layer has a plurality of crystal parts, and the crystal part has a c-axis oriented substantially perpendicular to the formation surface of the semiconductor layer or the top surface of the semiconductor layer, and there is no grain between adjacent crystal parts. It is preferable to use a metal oxide whose boundary cannot be confirmed.

  Since such a metal oxide does not have a crystal grain boundary, the occurrence of cracks in the metal oxide film due to stress when the display device is curved is suppressed. Therefore, such a metal oxide can be suitably used for a display device that has flexibility and is bent.

  In addition, by using a metal oxide having such crystallinity as a semiconductor layer, a change in electrical characteristics is suppressed and a highly reliable transistor can be realized.

  In addition, a transistor using a metal oxide having a larger band gap than silicon can hold charge accumulated in a capacitor connected in series with the transistor for a long time because of the low off-state current. By applying such a transistor to a pixel, the driving circuit can be stopped while maintaining the gradation of an image displayed in each display region. As a result, a display device with extremely reduced power consumption can be realized.

  The semiconductor layer is represented by an In-M-Zn-based oxide containing at least indium, zinc, and M (metal such as aluminum, titanium, gallium, germanium, yttrium, zirconium, lanthanum, cerium, tin, neodymium, or hafnium). It is preferable to include a film. In addition, in order to reduce variation in electric characteristics of the transistor using the metal oxide, it is preferable to include a stabilizer together with them.

  Examples of the stabilizer include the metals described in M above, and examples include gallium, tin, hafnium, aluminum, and zirconium. Other stabilizers include lanthanoids such as lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

  As a metal oxide forming the semiconductor layer, for example, an In—Ga—Zn-based oxide, an In—Al—Zn-based oxide, an In—Sn—Zn-based oxide, an In—Hf—Zn-based oxide, an In— La-Zn oxide, In-Ce-Zn oxide, In-Pr-Zn oxide, In-Nd-Zn oxide, In-Sm-Zn oxide, In-Eu-Zn oxide In-Gd-Zn-based oxide, In-Tb-Zn-based oxide, In-Dy-Zn-based oxide, In-Ho-Zn-based oxide, In-Er-Zn-based oxide, In-Tm -Zn oxide, In-Yb-Zn oxide, In-Lu-Zn oxide, In-Sn-Ga-Zn oxide, In-Hf-Ga-Zn oxide, In-Al- Ga-Zn oxide, In-Sn-Al-Zn oxide, In-Sn-Hf-Zn acid Things, can be used In-Hf-Al-Zn-based oxide.

  Note that here, an In—Ga—Zn-based oxide means an oxide containing In, Ga, and Zn as its main components, and there is no limitation on the ratio of In, Ga, and Zn. Moreover, metal elements other than In, Ga, and Zn may be contained.

  In addition, the semiconductor layer and the conductive layer may have the same metal element among the above oxides. Manufacturing costs can be reduced by using the same metal element for the semiconductor layer and the conductive layer. For example, the manufacturing cost can be reduced by using metal oxide targets having the same metal composition. Further, an etching gas or an etching solution for processing the semiconductor layer and the conductive layer can be used in common. However, the semiconductor layer and the conductive layer may have different compositions even if they have the same metal element. For example, a metal element in a film may be detached during a manufacturing process of a transistor and a capacitor to have a different metal composition.

  The metal oxide constituting the semiconductor layer preferably has an energy gap of 2 eV or more, preferably 2.5 eV or more, more preferably 3 eV or more. In this manner, off-state current of a transistor can be reduced by using a metal oxide having a wide energy gap.

  In the case where the metal oxide forming the semiconductor layer is an In-M-Zn oxide, the atomic ratio of the metal elements of the sputtering target used for forming the In-M-Zn oxide is In ≧ M, Zn ≧ It is preferable to satisfy 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, 4: 2: 4.1 and the like are preferable. Note that the atomic ratio of the semiconductor layer to be formed includes a variation of plus or minus 40% of the atomic ratio of the metal element contained in the sputtering target as an error.

As the semiconductor layer, a metal oxide film with low carrier density is used. For example, the semiconductor layer has a carrier density of 1 × 10 ¹⁷ / cm ³ or less, preferably 1 × 10 ¹⁵ / cm ³ or less, more preferably 1 × 10 ¹³ / cm ³ or less, more preferably 1 × 10 ¹¹ / cm 3. ³ or less, more preferably less than 1 × ^{10 10} / cm ^3, it is possible to use a 1 × ¹⁰ -9 / cm ³ metal oxide or more carrier density. Such metal oxides are referred to as high purity intrinsic or substantially high purity intrinsic metal oxides. Accordingly, it can be said that the metal oxide has stable characteristics because the impurity concentration is low and the density of defect states is low.

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

If the metal oxide constituting the semiconductor layer contains silicon or carbon which is one of the Group 14 elements, oxygen vacancies increase in the semiconductor layer and become n-type. Therefore, the concentration of silicon or carbon in the semiconductor layer (concentration obtained by secondary ion mass spectrometry) is 2 × 10 ¹⁸ atoms / cm ³ or less, preferably 2 × 10 ¹⁷ atoms / cm ³ or less.

In addition, when an alkali metal and an alkaline earth metal are combined with a metal oxide, carriers may be generated, which may increase the off-state current of the transistor. Therefore, the concentration of alkali metal or alkaline earth metal obtained by secondary ion mass spectrometry in the semiconductor layer is set to 1 × 10 ¹⁸ atoms / cm ³ or less, preferably 2 × 10 ¹⁶ atoms / cm ³ or less.

In addition, when nitrogen is contained in the metal oxide constituting the semiconductor layer, electrons as carriers are generated, the carrier density is increased, and the n-type is easily obtained. As a result, a transistor using a metal oxide containing nitrogen is likely to be normally on. For this reason, it is preferable that the nitrogen concentration obtained by secondary ion mass spectrometry in the semiconductor layer is 5 × 10 ¹⁸ atoms / cm ³ or less.

  The semiconductor layer may have a non-single crystal structure, for example. The non-single-crystal structure is, for example, a CAAC-OS (C-Axis Crystalline Oxide Semiconductor Semiconductor, C-Axis Aligned and A-B-Plane Annealed Crystalline Oxide Semiconductor Crystal Structure, Amorphous Crystal Structure, Includes structure. In the non-single-crystal structure, the amorphous structure has the highest density of defect states, and the CAAC-OS has the lowest density of defect states.

  An amorphous metal oxide film has, for example, disordered atomic arrangement and no crystal component. Alternatively, an amorphous oxide film has, for example, a completely amorphous structure and does not have a crystal part.

  Note that the semiconductor layer may be a mixed film including two or more of an amorphous structure region, a microcrystalline structure region, a polycrystalline structure region, a CAAC-OS region, and a single crystal structure region. Good. For example, the mixed film may have a single-layer structure or a stacked structure including any two or more of the above-described regions.

  In this specification and the like, a metal oxide is a metal oxide in a broad expression. Metal oxides are classified into oxide insulators, oxide conductors (including transparent oxide conductors), oxide semiconductors (also referred to as oxide semiconductors or simply OS), and the like. For example, when a metal oxide is used for an active layer of a transistor, the metal oxide may be referred to as an oxide semiconductor. In other words, when a metal oxide has at least one of an amplifying function, a rectifying function, and a switching function, the metal oxide can be referred to as a metal oxide semiconductor, or OS for short. In the case of describing as an OS FET, it can be said to be a transistor including a metal oxide or an oxide semiconductor.

  In this specification and the like, metal oxides containing nitrogen may be collectively referred to as metal oxides. Further, a metal oxide containing nitrogen may be referred to as a metal oxynitride.

  Moreover, in this specification etc., it may describe as CAAC (c-axis aligned crystal) and CAC (cloud aligned complementary). Note that CAAC represents an example of a crystal structure, and CAC represents an example of a function or a material structure.

  In this specification and the like, a CAC-OS or a CAC-metal oxide has a conductive function in part of a material and an insulating function in part of the material, and the whole material is a semiconductor. It has the function of. Note that in the case where a CAC-OS or a CAC-metal oxide is used for an active layer of a transistor, the conductive function is a function of flowing electrons (or holes) serving as carriers, and the insulating function is an electron serving as carriers. It is a function that does not flow. By performing the conductive function and the insulating function in a complementary manner, a switching function (function to turn on / off) can be given to the CAC-OS or the CAC-metal oxide. In CAC-OS or CAC-metal oxide, by separating each function, both functions can be maximized.

  In this specification and the like, a CAC-OS or a CAC-metal oxide includes a conductive region and an insulating region. The conductive region has the above-described conductive function, and the insulating region has the above-described 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, respectively. In addition, the conductive region may be observed with the periphery blurred and connected in a cloud shape.

  In CAC-OS or CAC-metal oxide, the conductive region and the insulating region are each dispersed in a material with a size of 0.5 nm to 10 nm, preferably 0.5 nm to 3 nm. There is.

  Further, CAC-OS or CAC-metal oxide is composed of components having different band gaps. For example, CAC-OS or CAC-metal oxide includes a component having a wide gap caused by an insulating region and a component having a narrow gap caused by a conductive region. In the case of the configuration, when the carrier flows, the carrier mainly flows in the component having the narrow gap. In addition, the component having a narrow gap acts in a complementary manner to the component having a wide gap, and the carrier flows through the component having the wide gap in conjunction with the component having the narrow gap. Therefore, when the CAC-OS or the CAC-metal oxide is used for a channel region of a transistor, high current driving capability, that is, high on-state current and high field-effect mobility can be obtained in the on-state of the transistor.

  That is, CAC-OS or CAC-metal oxide can also be referred to as a matrix composite or a metal matrix composite.

  An example of the crystal structure of the metal oxide will be described. Note that in the following, an example of a metal oxide formed by a sputtering method using an In—Ga—Zn oxide target (In: Ga: Zn = 4: 2: 4.1 [atomic ratio]) will be described. Will be described. A metal oxide formed by a sputtering method at a substrate temperature of 100 ° C. to 130 ° C. using the above target is called sIGZO, and the substrate temperature is set to room temperature (RT) using the above target. The metal oxide formed by the method is referred to as tIGZO. For example, sIGZO has a crystal structure of one or both of nc (nano crystal) and CAAC. TIGZO has an nc crystal structure. Note that the room temperature (RT) here includes a temperature when the substrate is not intentionally heated.

<Configuration of CAC-OS>
A structure of a CAC (Cloud Aligned Complementary) -OS that can be used for the transistor disclosed in one embodiment of the present invention is described below.

  The CAC-OS is one structure of a material in which elements forming a metal oxide are unevenly distributed with a size of 0.5 nm to 10 nm, preferably 1 nm to 2 nm, or the vicinity thereof. In the following, in the metal oxide, one or more metal elements are unevenly distributed, and the region having the metal element has a size of 0.5 nm to 10 nm, preferably 1 nm to 2 nm, or the vicinity thereof. The state mixed with is also referred to as a mosaic or patch.

  Note that the metal oxide preferably contains at least indium. In particular, it is preferable to contain indium and zinc. In addition, aluminum, gallium, yttrium, copper, vanadium, beryllium, boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, etc. One kind selected from the above or a plurality of kinds may be included.

For example, a CAC-OS in In-Ga-Zn oxide (In-Ga-Zn oxide among CAC-OSs may be referred to as CAC-IGZO in particular) is an indium oxide (hereinafter referred to as InO). _X1 (X1 is greater real than 0) and.), or indium zinc oxide _{(hereinafter, in X2 Zn Y2 O Z2 (} X2, Y2, and Z2 is larger real than 0) and a.), gallium An oxide (hereinafter referred to as GaO _X3 (X3 is a real number greater than 0)) or a gallium zinc oxide (hereinafter referred to as Ga _X4 Zn _Y4 O _Z4 (where X4, Y4, and Z4 are greater than 0)) to.) and the like, the material becomes mosaic by separate into, mosaic _{InO X1} or _in X2 _Zn Y2 _{O Z2,} is a configuration in which uniformly distributed in the film (hereinafter Also referred to as a cloud-like.) A.

That, CAC-OS includes a region _{GaO X3} as a main _component, and In _{X2 Zn} Y2 _{O Z2,} or _{InO X1} as a main component region is a composite metal oxide having a structure that is mixed. Note that in this specification, for example, the first region indicates that the atomic ratio of In to the element M in the first region is larger than the atomic ratio of In to the element M in the second region. It is assumed that the concentration of In is higher than that in the second region.

Note that IGZO is a common name and may refer to one compound of In, Ga, Zn, and O. As a typical example, 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) A crystalline compound may be mentioned.

  The crystalline compound has a single crystal structure, a polycrystalline structure, or a CAAC structure. The CAAC structure is a crystal structure in which a plurality of IGZO nanocrystals have c-axis orientation and are connected without being oriented in the ab plane.

  On the other hand, CAC-OS relates to a material structure of a metal oxide. CAC-OS refers to a region observed in the form of nanoparticles mainly composed of Ga in a material structure including In, Ga, Zn and O, and nanoparticles mainly composed of In. The region observed in a shape is a configuration in which the regions are randomly dispersed in a mosaic shape. Therefore, in the CAC-OS, the crystal structure is a secondary element.

  Note that the CAC-OS does not include a stacked structure of two or more kinds of films having different compositions. For example, a structure composed of two layers of a film mainly containing In and a film mainly containing Ga is not included.

Incidentally, a region _{GaO X3} is the main _component, and In _{X2 Zn} Y2 _{O Z2} or _{InO X1} is the main component region, in some cases clear boundary can not be observed.

In place of gallium, aluminum, yttrium, copper, vanadium, beryllium, boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, or magnesium are selected. In the case where one or a plurality of types are included, the CAC-OS includes a region that is observed in a part of a nanoparticle mainly including the metal element and a nanoparticle mainly including In. The region observed in the form of particles refers to a configuration in which each region is randomly dispersed in a mosaic shape.

  The CAC-OS can be formed by a sputtering method under a condition where the substrate is not intentionally heated, for example. In the case where a CAC-OS is formed by a sputtering method, any one or more selected from an inert gas (typically argon), an oxygen gas, and a nitrogen gas may be used as a deposition gas. Good. Further, the flow rate ratio of the oxygen gas to the total flow rate of the deposition gas during film formation is preferably as low as possible. For example, the flow rate ratio of the oxygen gas is 0% to less than 30%, preferably 0% to 10%. .

  The CAC-OS is characterized in that no clear peak is observed when it is measured using a θ / 2θ scan by the out-of-plane method, which is one of the X-ray diffraction (XRD) measurement methods. Have. That is, it can be seen from X-ray diffraction that no orientation in the ab plane direction and c-axis direction of the measurement region is observed.

  In addition, in the CAC-OS, an electron diffraction pattern obtained by irradiating an electron beam with a probe diameter of 1 nm (also referred to as a nanobeam electron beam) has a ring-like region having a high luminance and a plurality of bright regions in the ring region. A point is observed. Therefore, it can be seen from the electron beam diffraction pattern that the crystal structure of the CAC-OS has an nc (nano-crystal) structure having no orientation in the planar direction and the cross-sectional direction.

Further, for example, in a CAC-OS in an In—Ga—Zn oxide, a region in which GaO _X3 is a main component is obtained by EDX mapping obtained by using energy dispersive X-ray spectroscopy (EDX). It can be confirmed that a region in which In _X2 Zn _Y2 O _Z2 or InO _X1 is a main component is unevenly distributed and mixed.

The CAC-OS has a structure different from that of the IGZO compound in which the metal element is uniformly distributed, and has a property different from that of the IGZO compound. That is, in the CAC-OS, a region in which GaO _X3 or the like is a main component and a region in which In _X2 Zn _Y2 O _Z2 or InO _X1 is a main component are phase-separated from each other, and each region is mainly composed of each element. Has a mosaic structure.

Here, the region containing In _X2 Zn _Y2 O _Z2 or InO _X1 as a main component is a region having higher conductivity than a region containing GaO _X3 or the like as a main component. _That, In _{X2 Zn} Y2 _{O Z2} or _{InO X1,} is an area which is the main component, by carriers flow, conductive metal oxide is expressed. Accordingly, a region where In _X2 Zn _Y2 O _Z2 or InO _X1 is a main component is distributed in a cloud shape in the metal oxide, so that high field-effect mobility (μ) can be realized.

On the other hand, areas such as _{GaO X3} is the main _component, as compared to the In _{X2 Zn} Y2 _{O Z2} or _{InO X1} is the main component area, it is highly regions insulating. That is, since the region mainly composed of GaO _X3 or the like is distributed in the metal oxide, a leakage current can be suppressed and a good switching operation can be realized.

Therefore, when CAC-OS is used for a semiconductor element, the insulating property caused by GaO _{X3 and the} like and the conductivity caused by In _X2 Zn _Y2 O _Z2 or InO _X1 act in a complementary manner, resulting in high An on-current (I _on ) and high field effect mobility (μ) can be realized.

  In addition, a semiconductor element using a CAC-OS has high reliability. Therefore, the CAC-OS is optimal for various semiconductor devices including a display.

  Alternatively, silicon is preferably used for a semiconductor in which a channel of the transistor is formed. Although amorphous silicon may be used as silicon, it is particularly preferable to use silicon having crystallinity. For example, microcrystalline silicon, polycrystalline silicon, single crystal silicon, or the like is preferably used. 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. By applying such a polycrystalline semiconductor to a pixel, the aperture ratio of the pixel can be improved. Even in the case of a display portion with extremely high definition, the gate driver circuit and the source driver circuit can be formed over the same substrate as the pixel, and the number of components included in the electronic device can be reduced.

  The bottom-gate transistor described in this embodiment is preferable because the number of manufacturing steps can be reduced. At this time, since amorphous silicon can be used at a lower temperature than polycrystalline silicon, it is possible to use a material having low heat resistance as the electrode material and substrate material for the wiring below the semiconductor layer. Can widen the choice of materials. For example, a glass substrate having an extremely large area can be suitably used. On the other hand, a top-gate transistor is preferable because an impurity region can be easily formed in a self-aligning manner and variation in characteristics can be reduced. At this time, it is particularly suitable when polycrystalline silicon, single crystal silicon or the like is used.

[Conductive layer]
In addition to the gate, source, and drain of a transistor, materials that can be used for conductive layers such as various wirings and electrodes that constitute a display device include aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, A metal such as tantalum or tungsten, or an alloy containing the same as a main component can be given. A film containing any of these materials can be used as a single layer or a stacked structure. For example, a single layer structure of an aluminum film containing silicon, a two layer structure in which an aluminum film is stacked on a titanium film, a two layer structure in which an aluminum film is stacked on a tungsten film, and a copper film on a copper-magnesium-aluminum alloy film Two-layer structure to stack, two-layer structure to stack copper film on titanium film, two-layer structure to stack copper film on tungsten film, titanium film or titanium nitride film, and aluminum film or copper film on top of it A three-layer structure for forming a titanium film or a titanium nitride film thereon, a molybdenum film or a molybdenum nitride film, and an aluminum film or a copper film stacked thereon, and a molybdenum film or a There is a three-layer structure for forming a molybdenum nitride film. Note that an oxide such as indium oxide, tin oxide, or zinc oxide may be used. Further, it is preferable to use copper containing manganese because the controllability of the shape by etching is increased.

  As the light-transmitting conductive material, conductive oxide such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, or zinc oxide to which gallium is added, or graphene can be used. Alternatively, a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or titanium, or an alloy material containing the metal material can be used. Alternatively, a nitride (eg, titanium nitride) of the metal material may be used. Note that in the case where a metal material or an alloy material (or a nitride thereof) is used, it may be thin enough to have a light-transmitting property. In addition, a stacked film of the above materials can be used as a conductive layer. For example, it is preferable to use a laminated film of an alloy of silver and magnesium and indium tin oxide because the conductivity can be increased. These can also be used for conductive layers such as various wirings and electrodes constituting the display device and conductive layers (conductive layers functioning as pixel electrodes and common electrodes) included in the display element.

[Insulating layer]
Insulating materials that can be used for each insulating layer include, for example, resins such as acrylic and epoxy, resins having a siloxane bond, and inorganic insulation such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide. Materials can also be used.

  The light-emitting element is preferably provided between a pair of insulating films with low water permeability. Thereby, impurities such as water can be prevented from entering the light emitting element, and a decrease in reliability of the apparatus can be suppressed.

  Examples of the low water-permeable insulating film include a film containing nitrogen and silicon such as a silicon nitride film and a silicon nitride oxide film, and a film containing nitrogen and aluminum such as an aluminum nitride film. Alternatively, a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, or the like may be used.

For example, the water vapor transmission rate of an insulating film with low water permeability is 1 × 10 ⁻⁵ [g / (m ² · day)] or less, preferably 1 × 10 ⁻⁶ [g / (m ² · day)] or less, More preferably, it is 1 × 10 ⁻⁷ [g / (m ² · day)] or less, and further preferably 1 × 10 ⁻⁸ [g / (m ² · day)] or less.

[Liquid crystal element]
As the liquid crystal element, for example, a liquid crystal element to which a vertical alignment (VA: Vertical Alignment) mode is applied can be used. As the vertical alignment mode, an MVA (Multi-Domain Vertical Alignment) mode, a PVA (Patterned Vertical Alignment) mode, an ASV (Advanced Super View) mode, or the like can be used.

  As the liquid crystal element, liquid crystal elements to which various modes are applied can be used. For example, in addition to the VA mode, a TN (Twisted Nematic) mode, an IPS (In-Plane-Switching) mode, an FFS (Fringe Field Switching) mode, an ASM (Axially Symmetrical Aligned Micro-cell) mode, Further, a liquid crystal element to which an FLC (Ferroelectric Liquid Crystal) mode, an AFLC (Antiferroelectric Liquid Crystal) mode, or the like is applied can be used.

  Note that a liquid crystal element is an element that controls transmission or non-transmission of light by an optical modulation action of liquid crystal. Note that the optical modulation action of the liquid crystal is controlled by an electric field applied to the liquid crystal (including a horizontal electric field, a vertical electric field, or an oblique electric field). As the liquid crystal used in the liquid crystal element, a thermotropic liquid crystal, a low molecular liquid crystal, a polymer liquid crystal, a polymer dispersed liquid crystal (PDLC), a ferroelectric liquid crystal, an antiferroelectric liquid crystal, or the like is used. Can do. These liquid crystal materials exhibit a cholesteric phase, a smectic phase, a cubic phase, a chiral nematic phase, an isotropic phase, and the like depending on conditions.

  Further, as the liquid crystal material, either a positive type liquid crystal or a negative type liquid crystal may be used, and an optimal liquid crystal material may be used according to an applied mode or design.

  An alignment film can be provided to control the alignment of the liquid crystal. Note that in the case of employing a horizontal electric field mode, liquid crystal exhibiting a blue phase for which an alignment film is unnecessary may be used. The blue phase is one of the liquid crystal phases. When the temperature of the cholesteric liquid crystal is increased, the blue phase appears immediately before the transition from the cholesteric phase to the isotropic phase. Since the blue phase appears only in a narrow temperature range, a liquid crystal composition mixed with several percent by weight or more of a chiral agent is used for the liquid crystal layer in order to improve the temperature range. A liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent has a short response speed and is optically isotropic. In addition, a liquid crystal composition including a liquid crystal exhibiting a blue phase and a chiral agent does not require alignment treatment and has a small viewing angle dependency. Further, since it is not necessary to provide an alignment film, a rubbing process is not required, so that electrostatic breakdown caused by the rubbing process can be prevented, and defects or breakage of the liquid crystal display device during the manufacturing process can be reduced. .

  As the liquid crystal element, a transmissive liquid crystal element, a reflective liquid crystal element, a transflective liquid crystal element, or the like can be used.

  In one embodiment of the present invention, a reflective liquid crystal element can be used.

In the case of using a transmissive or transflective liquid crystal element, two polarizing plates are provided so as to sandwich a pair of substrates. A backlight is provided outside the polarizing plate. The backlight may be a direct type backlight or an edge light type backlight. It is preferable to use a direct-type backlight including an LED (Light Emitting Diode) because local dimming is facilitated and contrast can be increased. An edge light type backlight is preferably used because the thickness of the module including the backlight can be reduced.
Therefore, it is preferable.

  In the case of using a reflective liquid crystal element, a polarizing plate is provided on the display surface side. Separately from this, it is preferable to arrange a light diffusing plate on the display surface side because the visibility can be improved.

  In the case of using a reflective or transflective liquid crystal element, a front light may be provided outside the polarizing plate. As the front light, an edge light type front light is preferably used. It is preferable to use a front light including an LED (Light Emitting Diode) because power consumption can be reduced.

[Light emitting element]
As the light-emitting element, an element capable of self-emission can be used, and an element whose luminance is controlled by current or voltage is included in its category. For example, an LED, an organic EL element, an inorganic EL element, or the like can be used.

  Light emitting elements include a top emission type, a bottom emission type, and a dual emission type. A conductive film that transmits visible light is used for the electrode from which light is extracted. In addition, a conductive film that reflects visible light is preferably used for the electrode from which light is not extracted.

  The EL layer has at least a light emitting layer. The EL layer is a layer other than the light-emitting layer, such as a substance having a high hole injection property, a substance having a high hole transport property, a hole blocking material, a substance having a high electron transport property, a substance having a high electron injection property, or a bipolar property. A layer including a substance (a substance having a high electron transporting property and a high hole transporting property) and the like may be further included.

  Either a low molecular compound or a high molecular compound can be used for the EL layer, and an inorganic compound may be included. The layers constituting the EL layer can be formed by a method such as a vapor deposition method (including a vacuum vapor deposition method), a transfer method, a printing method, an ink jet method, or a coating method.

  When a voltage higher than the threshold voltage of the light emitting element is applied between the cathode and the anode, holes are injected into the EL layer from the anode side and electrons are injected from the cathode side. The injected electrons and holes are recombined in the EL layer, and the light-emitting substance contained in the EL layer emits light.

  In the case where a white light-emitting element is used as the light-emitting element, the EL layer preferably includes two or more light-emitting substances. For example, white light emission can be obtained by selecting the light emitting material so that the light emission of each of the two or more light emitting materials has a complementary color relationship. For example, a light emitting material that emits light such as R (red), G (green), B (blue), Y (yellow), and O (orange), or spectral components of two or more colors of R, G, and B It is preferable that 2 or more are included among the luminescent substances which show light emission containing. In addition, it is preferable to apply a light-emitting element whose emission spectrum from the light-emitting element has two or more peaks within a wavelength range of visible light (for example, 350 nm to 750 nm). The emission spectrum of the material having a peak in the yellow wavelength region is preferably a material having spectral components in the green and red wavelength regions.

  The EL layer preferably has a structure in which a light-emitting layer including a light-emitting material that emits one color and a light-emitting layer including a light-emitting material that emits another color are stacked. For example, the plurality of light emitting layers in the EL layer may be stacked in contact with each other, or may be stacked through a region not including any light emitting material. For example, a region including the same material (for example, a host material or an assist material) as the fluorescent light emitting layer or the phosphorescent light emitting layer and not including any light emitting material is provided between the fluorescent light emitting layer and the phosphorescent light emitting layer. Also good. This facilitates the production of the light emitting element and reduces the driving voltage.

  The light-emitting element may be a single element having one EL layer or a tandem element in which a plurality of EL layers are stacked with a charge generation layer interposed therebetween.

  The conductive film that transmits visible light can be formed using, for example, indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide to which gallium is added, or the like. In addition, a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or titanium, an alloy including these metal materials, or a nitride of these metal materials (for example, Titanium nitride) can also be used by forming it thin enough to have translucency. In addition, a stacked film of the above materials can be used as a conductive layer. For example, it is preferable to use a stacked film of an alloy of silver and magnesium and indium tin oxide because the conductivity can be increased. Further, graphene or the like may be used.

  For the conductive film that reflects visible light, for example, a metal material such as aluminum, gold, platinum, silver, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, or palladium, or an alloy including these metal materials is used. Can do. In addition, lanthanum, neodymium, germanium, or the like may be added to the metal material or alloy. Alternatively, titanium, nickel, or neodymium and an alloy containing aluminum (aluminum alloy) may be used. Alternatively, an alloy containing copper, palladium, magnesium, and silver may be used. An alloy containing silver and copper is preferable because of its high heat resistance. Furthermore, oxidation can be suppressed by stacking a metal film or a metal oxide film in contact with the aluminum film or the aluminum alloy film. Examples of materials for such metal films and metal oxide films include titanium and titanium oxide. Alternatively, the conductive film that transmits visible light and a film made of a metal material may be stacked. For example, a laminated film of silver and indium tin oxide, a laminated film of an alloy of silver and magnesium and indium tin oxide, or the like can be used.

  The electrodes may be formed using a vapor deposition method or a sputtering method, respectively. In addition, it can be formed using a discharge method such as an inkjet method, a printing method such as a screen printing method, or a plating method.

  Note that the above-described light-emitting layer and a layer containing a substance having a high hole-injecting property, a substance having a high hole-transporting property, a substance having a high electron-transporting property, a substance having a high electron-injecting property, a bipolar substance, Each may have an inorganic compound such as a quantum dot or a polymer compound (oligomer, dendrimer, polymer, etc.). For example, a quantum dot can be used for a light emitting layer to function as a light emitting material.

  As the quantum dot material, a colloidal quantum dot material, an alloy type quantum dot material, a core / shell type quantum dot material, a core type quantum dot material, or the like can be used. Alternatively, a material including an element group of Group 12 and Group 16, Group 13 and Group 15, or Group 14 and Group 16 may be used. Alternatively, a quantum dot material containing an element such as cadmium, selenium, zinc, sulfur, phosphorus, indium, tellurium, lead, gallium, arsenic, or aluminum may be used.

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

  Further, the resin may contain a desiccant. For example, a substance that adsorbs moisture by chemical adsorption, such as an alkaline earth metal oxide (such as calcium oxide or barium oxide), can be used. Alternatively, a substance that adsorbs moisture by physical adsorption, such as zeolite or silica gel, may be used. The inclusion of a desiccant is preferable because impurities such as moisture can be prevented from entering the element and the reliability of the display device is improved.

  In addition, light extraction efficiency can be improved by mixing a filler having a high refractive index or a light scattering member with the resin. For example, titanium oxide, barium oxide, zeolite, zirconium, or the like can be used.

(Connection layer)
As the connection layer, an anisotropic conductive film (ACF: Anisotropic Conductive Film), an anisotropic conductive paste (ACP: Anisotropic Conductive Paste), or the like can be used.

(Colored layer)
Examples of materials that can be used for the colored layer include metal materials, resin materials, resin materials containing pigments or dyes, and the like.

[Light shielding layer]
Examples of the material that can be used for the light-shielding layer include carbon black, titanium black, metal, metal oxide, and composite oxide containing a solid solution of a plurality of metal oxides. The light shielding layer may be a film containing a resin material or a thin film of an inorganic material such as a metal. Alternatively, a stacked film of a film containing a material for the colored layer can be used for the light shielding layer. For example, a stacked structure of a film including a material used for a colored layer that transmits light of a certain color and a film including a material used for a colored layer that transmits light of another color can be used. It is preferable to use a common material for the coloring layer and the light-shielding layer because the apparatus can be shared and the process can be simplified.

  The above is the description of each component.

[Example of production method]
Here, an example of a substrate peeling method and a method for manufacturing a display panel including a flexible substrate to which the substrate peeling method is applied will be described.

  Here, a layer including a display element, a circuit, a wiring, an electrode, an optical member such as a coloring layer or a light shielding layer, and an insulating layer is collectively referred to as an element layer. For example, the element layer includes a display element, and may include an element such as a wiring that is electrically connected to the display element, a transistor used for a pixel, or a circuit in addition to the display element.

  Here, a member that supports the element layer and has flexibility when the display element is completed (the manufacturing process is completed) is referred to as a substrate. For example, the substrate includes a very thin film having a thickness of 10 nm to 300 μm.

  As a method for forming an element layer over a flexible substrate having an insulating surface, there are typically two methods described below. One is a method of forming an element layer directly on a substrate. The other is a method in which an element layer is formed on a support substrate different from the substrate, the element layer and the support base material are peeled off, and the element layer is transferred to the substrate. Although not described in detail here, in addition to the two methods described above, a method of providing flexibility by forming an element layer on a non-flexible substrate and thinning the substrate by polishing or the like. There is also.

  In the case where the material constituting the substrate has heat resistance against the heat applied to the element layer forming step, it is preferable to form the element layer directly on the substrate because the process is simplified. At this time, it is preferable to form the element layer in a state in which the substrate is fixed to the supporting base material, because it is easy to carry the device inside and between the devices.

  In the case of using a method in which the element layer is formed on the supporting base material and then transferred to the substrate, a peeling layer and an insulating layer are first stacked on the supporting base material, and the element layer is formed on the insulating layer. Then, it peels between a support base material and an element layer, and transfers an element layer to a board | substrate. At this time, a material that causes peeling in the interface between the support base and the release layer, the interface between the release layer and the insulating layer, or the release layer may be selected. In this method, by using a material having high heat resistance for the support substrate and the release layer, the upper limit of the temperature required for forming the element layer can be increased when forming the element layer, and the reliability is higher. It is preferable because an element layer having elements can be formed.

  For example, a layer containing a high-melting-point metal material such as tungsten and a layer containing an oxide of the metal material are stacked as the separation layer, and silicon oxide, silicon nitride, silicon oxynitride, It is preferable to use a layer in which a plurality of silicon nitride oxides or the like are stacked. Note that in this specification, oxynitride refers to a material having a higher oxygen content than nitrogen as its composition, and nitride oxide refers to a material having a higher nitrogen content than oxygen as its composition. Point to.

  Examples of the method for peeling the element layer and the supporting substrate include applying a mechanical force, etching the peeling layer, or infiltrating a liquid into the peeling interface. Alternatively, peeling may be performed by heating or cooling using a difference in thermal expansion between the two layers forming the peeling interface.

  In the case where peeling is possible at the interface between the support base and the insulating layer, the peeling layer may not be provided.

  For example, glass can be used as the supporting substrate, and an organic resin such as polyimide can be used as the insulating layer. At this time, after the element layer is formed, the organic resin can be irradiated with laser light or the like to improve the peelability between the support substrate and the organic resin, and can be peeled off. Thereby, it is possible to prevent unintentional peeling when the element layer is formed.

  Also, at the time of peeling, a starting point of peeling is formed by locally heating a part of the organic resin using a laser beam or the like, or physically cutting or penetrating a part of the organic resin by a sharp member. Alternatively, peeling may be performed at the interface between the glass and the organic resin.

  Alternatively, a heat generation layer may be provided between the support base and the insulating layer made of an organic resin, and the heat generation layer may be heated to peel off the interface between the heat generation layer and the insulation layer. As the heat generating layer, various materials such as a material that generates heat when an electric current flows, a material that generates heat by absorbing light, and a material that generates heat by applying a magnetic field can be used. For example, the heat generating layer can be selected from semiconductors, metals, and insulators.

  In the above-described method, the insulating layer made of an organic resin can be used as a substrate after peeling.

  The above is the description of the method for manufacturing a flexible display panel.

  This embodiment can be implemented in appropriate combination with at least part of the other embodiments described in this specification.

(Embodiment 3)
In this embodiment, more specific examples of the display device of one embodiment of the present invention will be described with reference to drawings.

  FIG. 13A is a block diagram of the display device 400. The display device 400 includes a display unit 362, a circuit GD, and a circuit SD. The display portion 362 includes a plurality of pixels 410 arranged in a matrix.

  The display device 400 includes a plurality of wirings G1, a plurality of wirings G2, a plurality of wirings ANO, a plurality of wirings CSCOM, a plurality of wirings S1, and a plurality of wirings S2. The plurality of wirings G1, the plurality of wirings G2, the plurality of wirings ANO, and the plurality of wirings CSCOM are electrically connected to the plurality of pixels 410 and the circuit GD arranged in the direction indicated by the arrow R, respectively. The plurality of wirings S1 and the plurality of wirings S2 are electrically connected to the plurality of pixels 410 and the circuit SD arranged in the direction indicated by the arrow C, respectively.

  Note that, here, for the sake of simplicity, a configuration including one circuit GD and one circuit SD is shown; however, the circuit GD and the circuit SD that drive the liquid crystal element and the circuit GD and the circuit SD that drive the light emitting element are separately provided. May be provided.

  The pixel 410 includes a reflective liquid crystal element and a light-emitting element.

  FIGS. 13B1 and 13B2 illustrate configuration examples of the electrode 311 included in the pixel 410. FIG. The electrode 311 functions as a reflective electrode of the liquid crystal element.

  In FIGS. 13B1 and 13B2, the light-emitting element 360 located in a region overlapping with the electrode 311 is indicated by a broken line. Light emitted from the light emitting element 360 is emitted to the side opposite to the electrode 311.

  In FIG. 13B1, the pixels 410 adjacent in the direction indicated by the arrow R are pixels corresponding to different colors. In FIG. 13 (B2), adjacent pixels 410 in the direction indicated by arrow C are pixels corresponding to different colors.

  Various sequential circuits such as a shift register can be used for the circuit GD. A transistor, a capacitor, or the like can be used for the circuit GD. A transistor included in the circuit GD can be formed in the same process as the transistor included in the pixel 410.

  The circuit SD is electrically connected to the wiring S1. For the circuit SD, for example, an integrated circuit can be used. Specifically, an integrated circuit formed on a silicon substrate can be used for the circuit SD.

  For example, the circuit SD can be mounted on a pad electrically connected to the pixel 410 by using a COG (Chip on glass) method, a COF method, or the like. Specifically, an integrated circuit can be mounted on the pad using an anisotropic conductive film.

  FIG. 14 is an example of a circuit diagram of the pixel 410. In FIG. 14, two adjacent pixels 410 are shown.

  The pixel 410 includes a switch SW1, a capacitor C1, a liquid crystal element 340, a switch SW2, a transistor M, a capacitor C2, a light emitting element 360, and the like. In addition, a wiring G1, a wiring G2, a wiring ANO, a wiring CSCOM, a wiring S1, and a wiring S2 are electrically connected to the pixel 410. In FIG. 14, a wiring VCOM1 electrically connected to the liquid crystal element 340 and a wiring VCOM2 electrically connected to the light emitting element 360 are illustrated.

  FIG. 14 shows an example in which transistors are used for the switch SW1 and the switch SW2.

  The gate of the switch SW1 is connected to the wiring G1. One of the source and the drain of the switch SW1 is connected to the wiring S1, and the other is connected to one electrode of the capacitor C1 and one electrode of the liquid crystal element 340. The other electrode of the capacitive element C1 is connected to the wiring CSCOM. The other electrode of the liquid crystal element 340 is connected to the wiring VCOM1.

  The gate of the switch SW2 is connected to the wiring G2. One of the source and the drain of the switch SW2 is connected to the wiring S2, and the other is connected to one electrode of the capacitor C2 and the gate of the transistor M. The other electrode of the capacitor C2 is connected to one of the source and the drain of the transistor M and the wiring ANO. The other of the source and the drain of the transistor M is connected to one electrode of the light emitting element 360. The other electrode of the light emitting element 360 is connected to the wiring VCOM2.

  FIG. 14 shows an example in which the transistor M has two gates sandwiching a semiconductor and these are connected. As a result, the current that can be passed by the transistor M can be increased.

  A signal for controlling the switch SW1 to be in a conductive state or a non-conductive state can be supplied to the wiring G1. A predetermined potential can be applied to the wiring VCOM1. A signal for controlling the alignment state of the liquid crystal included in the liquid crystal element 340 can be supplied to the wiring S1. A predetermined potential can be applied to the wiring CSCOM.

  A signal for controlling the switch SW2 to be in a conductive state or a non-conductive state can be supplied to the wiring G2. The wiring VCOM2 and the wiring ANO can each be supplied with a potential at which a potential difference generated by the light emitting element 360 emits light. A signal for controlling the conduction state of the transistor M can be supplied to the wiring S2.

  For example, in the case of performing reflection mode display, the pixel 410 illustrated in FIG. 14 is driven by a signal supplied to the wiring G1 and the wiring S1, and can display using optical modulation by the liquid crystal element 340. In the case where display is performed in the transmissive mode, display can be performed by driving the light-emitting element 360 by driving with signals supplied to the wiring G2 and the wiring S2. In the case of driving in both modes, the driving can be performed by signals given to the wiring G1, the wiring G2, the wiring S1, and the wiring S2.

  Note that although FIG. 14 illustrates an example in which one pixel 410 includes one liquid crystal element 340 and one light emitting element 360, the invention is not limited thereto. FIG. 15A illustrates an example in which one pixel 410 includes one liquid crystal element 340 and four light-emitting elements 360 (light-emitting elements 360r, 360g, 360b, and 360w). Unlike the pixel 410 illustrated in FIG. 14, the pixel 410 illustrated in FIG. 15A can perform full-color display using a light-emitting element in one pixel.

  In FIG. 15A, in addition to the example of FIG. 14, a wiring G3 and a wiring S3 are connected to the pixel 410.

  In the example illustrated in FIG. 15A, for example, light emitting elements exhibiting red (R), green (G), blue (B), and white (W) can be used for the four light emitting elements 360, respectively. As the liquid crystal element 340, a reflective liquid crystal element exhibiting white can be used. Thereby, when displaying in reflection mode, white display with high reflectance can be performed. In addition, when display is performed in the transmissive mode, display with high color rendering properties can be performed with low power.

  FIG. 15B illustrates a configuration example of the pixel 410 corresponding to FIG. The pixel 410 includes a light-emitting element 360w, a light-emitting element 360r, a light-emitting element 360g, and a light-emitting element 360b that overlap with the electrode 311. The light emitting element 360r, the light emitting element 360g, and the light emitting element 360b preferably have substantially the same light emitting area.

  This embodiment can be implemented in appropriate combination with at least part of the other embodiments described in this specification.

(Embodiment 4)
In this embodiment, examples of electronic devices each including the display device of one embodiment of the present invention are described with reference to drawings.

  By using the display device of one embodiment of the present invention, an electronic device having two display portions can be manufactured. In addition, an electronic device with improved convenience can be manufactured. In addition, an electronic device that can perform display suitable for a use environment, a use method, and an image to be displayed can be manufactured. In addition, an electronic device with reduced power consumption can be manufactured. In addition, a highly reliable electronic device can be manufactured. In addition, an unprecedented electronic device can be manufactured. In addition, an electronic device excellent in design can be manufactured. In addition, an electronic device with excellent versatility can be manufactured. In addition, a lightweight and highly portable electronic device can be manufactured. In addition, a compact electronic device can be manufactured.

  Electronic devices include, for example, television devices, desktop or notebook personal computers, monitors for computers, digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, personal digital assistants, audio devices Large game machines such as playback devices and pachinko machines are listed.

  The electronic device of one embodiment of the present invention may include a secondary battery, and it is preferable that the secondary battery can be charged using non-contact power transmission. Secondary batteries include, for example, lithium ion secondary batteries such as lithium polymer batteries (lithium ion polymer batteries) using gel electrolyte, nickel metal hydride batteries, nickel-cadmium batteries, organic radical batteries, lead storage batteries, air secondary batteries, nickel A zinc battery, a silver zinc battery, etc. are mentioned.

  The electronic device of one embodiment of the present invention may include an antenna. By receiving a signal with an antenna, video, information, and the like can be displayed on the display unit. In the case where the electronic device has an antenna and a secondary battery, the antenna may be used for non-contact power transmission.

  The electronic device of one embodiment of the present invention includes a sensor (force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, It may have a function of measuring voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared).

  The electronic device of one embodiment of the present invention can have a variety of functions. For example, a function for displaying various information (still images, moving images, text images, etc.) on the display unit, a touch panel function, a function for displaying a calendar, date or time, a function for executing various software (programs), and wireless communication A function, a function of reading a program or data recorded on a recording medium, and the like can be provided.

  Further, in an electronic apparatus having a plurality of display units, a function that displays image information mainly on one display unit and mainly displays character information on another display unit, or parallax is considered in the plurality of display units. By displaying an image, a function of displaying a stereoscopic image can be provided. Furthermore, in an electronic device having an image receiving unit, a function for capturing a still image or a moving image, a function for automatically or manually correcting the captured image, and a function for saving the captured image in a recording medium (externally or incorporated in the electronic device) A function of displaying the photographed image on the display portion can be provided. Note that the functions of the electronic device of one embodiment of the present invention are not limited thereto, and the electronic device can have various functions.

  Hereinafter, more specific examples will be described with reference to the drawings.

  16A1 and 16A2 illustrate an electronic device 1000 to which the display device of one embodiment of the present invention is applied. The electronic device 1000 includes two display units 1002a and 1002b that are positioned back to back. 16A1 shows the display portion 1002a side, and FIG. 16A2 shows the display portion 1002b side.

  The electronic device 1000 includes a housing 1001, a display portion 1002a, a display portion 1002b, operation buttons 1003, a speaker 1004, a microphone 1005, an external connection port 1006, a camera 1007, and the like. Further, a frame portion 1008 is provided outside the display portion 1002a and the display portion 1002b.

  The display portion 1002a and the display portion 1002b include the display device of one embodiment of the present invention. One of the display portion 1002a and the display portion 1002b can display an image using reflected light, and the other of the display portion 1002a and the display portion 1002b can display an image using light emission.

  For example, the user can switch between the display unit 1002a and the display unit 1002b according to the usage environment and application. For example, when using in a place with bright external light or browsing document information, use a display unit that uses external light, and use it in an environment where the illuminance of external light is extremely low, such as at night or in a dark room. For example, when viewing a vivid image, a display unit using light emission can be used.

  In addition, by displaying images on both the display unit 1002a and the display unit 1002b, the user and a person positioned facing the user see images displayed on different display units. it can.

  The frame portion 1008 is a portion that protects end portions of the display portion 1002a and the display portion 1002b. The frame portion 1008 may be made of the same material as that of the housing 1001, but it is more preferable to use an elastic body such as rubber.

  At least one of the display portion 1002a and the display portion 1002b includes a touch sensor. All operations such as making a call or inputting characters can be performed by touching the display unit with a finger or a stylus.

  Further, by operating the operation button 1003, the power can be turned on and off, and the type of image displayed on the display portion 1002a or the display portion 1002b can be switched. For example, the mail creation screen can be switched to the main menu screen.

  Further, by providing a detection device such as a gyro sensor or an acceleration sensor in the housing 1001, the orientation of the electronic device (vertical or horizontal) is determined, and the screen display orientation of the display portion 1002a or the display portion 1002b is determined. Can be switched automatically. The screen display orientation can also be switched by touching the display portion 1002a or the display portion 1002b, operation of the operation buttons 1003, voice input using the microphone 1005, or the like.

  The electronic device 1000 illustrated in this embodiment functions as a portable information terminal. For example, it has one or a plurality of functions selected from a telephone, a notebook, an information browsing device, or the like. Specifically, it can be used as a smartphone. The electronic device 1000 exemplified in this embodiment can execute various applications such as a mobile phone, electronic mail, text browsing and creation, music playback, Internet communication, and computer games.

  In the electronic device 1000, the thickness of the portion where the display portion 1002a and the display portion 1002b are located can be extremely reduced. For example, the thickness of this portion can be reduced to 0.1 mm to 1 cm, preferably 0.2 mm to 5 mm, more preferably 0.5 mm to 3 mm. Therefore, an electronic device with extremely high portability can be obtained.

  Further, as in the electronic device 1010 illustrated in FIGS. 16B1 and 16B2, a seamless configuration can be provided without the frame portion 1008. Thereby, it can be set as the electronic device which was excellent in the designability.

  In the electronic device 1010 illustrated in FIGS. 16B1 and 16B2, since the frame portion 1008 is not provided, an electronic device which is not easily broken by using a resin substrate or the like for the display device which forms the display portion 1002a and the display portion 1002b. Can be realized. Further, the display device may be protected by covering the surface of the display device with resin or rubber.

  In addition, in the electronic device 1010 illustrated in FIGS. 16B1 and 16B2, the speaker may be incorporated in the housing 1001, or another speaker or an earphone or a headset worn by a user may be mounted using a short-range wireless communication technology. It is good also as a structure which transmits an audio | voice. Alternatively, the display portion 1002a and the display portion 1002b may be configured to emit sound by vibrating.

  17A to 17E illustrate an electronic device 1100. FIG.

  The electronic device 1100 includes a housing 1101, a housing 1102, and a hinge 1104. The housing 1101 and the housing 1102 are rotatably connected by a hinge 1104. In the electronic device 1100, the housing 1101 and the housing 1102 can be rotated approximately 360 degrees relative to the rotation axis of the hinge 1104.

  The housing 1101 and the housing 1102 are electrically connected by a cable passing through the inside of the hinge 1104. Thus, signals and power can be transmitted between the housing 1101 and the housing 1102. In addition, the images displayed on the display units provided in the respective housings can be synchronized.

  The housing 1101 has a display portion 1103a on one surface side and a display portion 1103c on the other surface side. The housing 1102 has a display portion 1103b on one surface side and a display portion 1103d on the other surface side.

  The display portion 1103a and the display portion 1103c included in the housing 1101 include the display device of one embodiment of the present invention. Further, the display portion 1103b and the display portion 1103d included in the housing 1102 include the display device of one embodiment of the present invention. One of the display portions 1103a and 1103c and one of the display portions 1103b and 1103d can display an image using reflected light, and the other of the display portions 1103a and 1103c and the display portion 1103b. The other of the display portion 1103d can display an image using light emission.

  Here, the display unit 1103a and the display unit 1103b each have a function of displaying an image using reflected light, and the display unit 1103c and the display unit 1103d can display an image using light emission. .

  FIG. 17A illustrates a state where the electronic device 1100 is closed. FIG. 17B illustrates a state in which FIG. 17A is viewed from the hinge 1104 side. At this time, the electronic device 1100 can be used as a tablet terminal capable of double-sided display. An image can be displayed on at least one of the display portion 1103a and the display portion 1103b. This mode is a mode in which power consumption can be reduced because display using reflected light can be performed.

  FIG. 17A illustrates a structure in which the housing 1101 includes an external connection port 1105 and a camera 1106. Further, the housing 1101 or the housing 1102 may be provided with a power button, operation buttons such as a volume adjustment button, an insertion port for a storage medium such as an optical disk or a memory card, and the like.

  FIGS. 17C and 17D show a state in which the housing 1101 and the housing 1102 are opened. In this state, an image can be displayed on each of the display portions 1103c and 1103d. In this form, vivid image display can be performed on the display portions 1103c and 1103d.

  In the modes shown in FIGS. 17C and 17D, for example, the display portion 1103c or the display portion 1103d can be used as a keyboard or a touch pad, so that it can be used as a laptop personal computer. In addition, by displaying images on the display portion 1103c and the display portion 1103d, it can be used as a book-type information terminal device.

  At this time, an image can also be displayed on the display unit 1103a positioned back to back with the display unit 1103c and the display unit 1103b positioned back to back with the display unit 1103d. For example, the design of the electronic device 1100 can be freely changed by, for example, displaying a still image. In addition, since an image can be shown to another person positioned facing the user, for example, a presentation can be performed while sitting face-to-face.

  FIG. 17E illustrates a state where the housing 1101 and the housing 1102 are opened 180 degrees. By adopting such a form, it can be used as a tablet terminal capable of double-sided display and having a wide display area.

  FIG. 17F illustrates a state in which the housing 1101 and the housing 1102 are folded so that the display portion 1103c and the display portion 1103d are located on the surface. In this mode, vivid display can be performed on the display portion 1103c or the display portion 1103d.

  As described above, the electronic device 1100 of one embodiment of the present invention is an electronic device in which the convenience is improved by changing the form in accordance with the use environment or the application.

  For example, when used as a tablet terminal, when used in a place where the outside light is bright, or when browsing document information or the like, the form shown in FIG. 17A is used and an image is displayed using reflected light. be able to. On the other hand, when used in an environment where the illuminance of outside light is extremely low, such as at night or in a dark room, or when viewing a vivid image, the image is formed using light emission as shown in FIG. Can be displayed.

  This embodiment can be implemented in appropriate combination with at least part of the other embodiments described in this specification.

DESCRIPTION OF SYMBOLS 10 Display apparatus 11 Display surface 12 Display surface 14 Display part 14a Display part 14b Display part 20a Light emission 20b Reflected light 21 Substrate 23 Conductive layer 23b Conductive layer 24 Liquid crystal 25 Conductive layer 30 Pixel unit 31 Substrate 31B Display element 31G Display element 31p Pixel 31R Display element 31W Display element 32 Substrate 32W Display element 32B Display element 32G Display element 32p Pixel 32R Display element 34 Circuit 35 Wiring 35e Light 35r Light 36 FPC
37 IC
40 display element 41 functional layer 41a substrate 41b substrate 43 release layer 44 support substrate 45 insulating layer 51a colored layer 51b colored layer 52 light shielding layer 52a colored layer 52b colored layer 53a alignment film 53b alignment film 61 insulating layer 70a transistor 70b transistor 71 conductive layer 72 Semiconductor layer 74a Conductive layer 74b Conductive layer 80 Connection portion 81 Insulating layer 82 Insulating layer 83 Insulating layer 84 Insulating layer 89 Adhesive layer 90 Display element 91 Conductive layer 92 EL layer 92a EL layer 92b EL layer 93 Conductive layer 94 Insulating layer 311 Electrode 340 Liquid crystal element 360 Light-emitting element 360b Light-emitting element 360g Light-emitting element 360r Light-emitting element 360w Light-emitting element 362 Display unit 400 Display device 410 Pixel 1000 Electronic device 1001 Housing 1002a Display unit 1002b Display unit 1003 Operation button 1004 Speaker 1005 Microphone 1 06 an external connection port 1007 camera 1008 frame portion 1010 Electronic Equipment 1100 Electronic Equipment 1101 housing 1102 housing 1103a display unit 1103b display unit 1103c display unit 1103d display unit 1104 hinge 1105 an external connection port 1106 Camera

Claims (9)

A display device having a first display element, a second display element, a first display surface, and a second display surface,
The first display element has a function of reflecting visible light on the first display surface side,
The second display element has a function of emitting visible light to the second display surface side,
The first display surface and the second display surface sandwich the first display element and the second display element and are located back to back;
Display device. A display having a first display element, a second display element, a first display surface, a second display surface, a first transistor, a second transistor, and a first insulating layer A device,
The first display element has a function of reflecting visible light on the first display surface side,
The second display element has a function of emitting visible light to the second display surface side,
The first display surface and the second display surface include the first display element, the second display element, the first transistor, the second transistor, and the first insulating layer. Sandwiched and located back to back,
The first transistor is electrically connected to the first display element;
The second transistor is electrically connected to the second display element;
The first transistor and the second transistor are respectively formed on the first surface side of the first insulating layer;
The first display element is located between the first insulating layer and the first display surface,
The second display element is located between the first insulating layer and the second display surface;
Display device. In claim 1 or claim 2,
The first display element is a reflective liquid crystal element.
Display device. In any one of Claim 1 thru | or 3,
The second display element is an electroluminescent element.
Display device. In any one of Claims 1 thru | or 4,
A plurality of the first display elements and a plurality of the second display elements;
The first display element and the second display element are arranged with the same definition, respectively.
Display device. In any one of Claims 1 thru | or 4,
A plurality of the first display elements and a plurality of the second display elements;
The first display element and the second display element are arranged with different resolutions, respectively.
Display device. In any one of Claims 1 thru | or 6,
At least one of the first transistor and the second transistor includes a metal oxide in a semiconductor layer in which a channel is formed.
Display device. A display device according to any one of claims 1 to 7, and a housing.
A first display unit located back to back and a second display unit,
The first display unit has a function of displaying an image using reflected light,
The second display unit has a function of displaying an image using light emission.
Electronics. In claim 8,
The housing includes any one or more of an operation button, a speaker, a microphone, a camera, an external connection port, an antenna, and a sensor.
Electronics.

Images