Electronic device and method for operating same

Abstract

The present invention provides an electronic device with good display visibility. The electronic device has a reflective liquid crystal display device for displaying information, wherein the reflective liquid crystal display device can be supplied with a portion of ambient light that is taken into the electronic device, and use said ambient light as a light source for display light. Therefore, the display visibility can be enhanced even in strong ambient light. Moreover, because ambient light is used for display, power consumption can be reduced compared to transmissive liquid crystal display devices, which use an always-on light source, and self-luminous OLED display devices.

Description

Electronic device and method of operation thereof

[0001] One aspect of the present invention relates to an electronic device.

[0002] Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Alternatively, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Therefore, more specifically, examples of the technical field of one embodiment of the present invention disclosed in this specification include a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, a power storage device, a memory device, an imaging device, and an operation method thereof or a manufacturing method thereof.

[0003] Note that in this specification and the like, a semiconductor device refers to any device that can function by utilizing semiconductor characteristics. A transistor and a semiconductor circuit are examples of a semiconductor device. In addition, a memory device, a display device, an imaging device, and an electronic device may include a semiconductor device.

[0004] As one type of display device, an active matrix liquid crystal display device that uses transistors as switching elements is known (see Patent Document 1).

[0005] Liquid crystal display devices are broadly divided into two types: transmissive and reflective. Semi-transmissive types, which combine the two, are also known.

[0006] A transmissive liquid crystal display device can display images by controlling the optical modulation action of the liquid crystal between a state in which light incident from a backlight passes through the liquid crystal display device and is output to the outside (bright) and a state in which no light is output (dark).

[0007] A reflective liquid crystal display device can display images by controlling the optical modulation action of the liquid crystal between a state in which light incident from the display surface side is reflected by the pixel electrodes and output to the outside (bright) and a state in which no light is output (dark).

[0008] WO2023 / 094937

[0009] Optical see-through eyeglass devices used as AR (Augmented Reality) compatible devices and the like are required to have high visibility of displayed information regardless of the illuminance of the environment in which they are used. Furthermore, to accommodate long periods of continuous use, they are also required to be small and lightweight, and to have low power consumption so that the battery does not need to be charged frequently.

[0010] Display devices used in eyeglass-type devices often include transmissive liquid crystal display devices that are easily visible over a relatively wide range of illuminance, or self-luminous display devices that include organic EL elements. However, these display devices have the problem that under high illuminance, the amount of display light becomes relatively small compared to external light, resulting in reduced visibility of the display. Furthermore, under high illuminance, the display brightness must be increased, which increases power consumption.

[0011] Reflective LCD devices utilize reflected light, providing excellent visibility of the display even under high illumination. When a reflective LCD device is used in an eyeglass-type device, the brightness can be increased and visibility can be improved if external light can be used as the display light. Although a light source such as a front light is required to improve visibility under low illumination, the power required for the light source can be reduced by using external light in combination.

[0012] Therefore, an object of one embodiment of the present invention is to provide an electronic device with high display visibility, an electronic device with low power consumption, a small and lightweight electronic device, a novel electronic device, or a method for operating the electronic device.

[0013] Note that the description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily solve all of these problems. Note that problems other than these will become clear from the description of the specification, drawings, claims, etc., and it is possible to extract other problems from the description of the specification, drawings, claims, etc.

[0014] One embodiment of the present invention relates to an electronic device having a display with good visibility.

[0015] One embodiment of the present invention is an electronic device that has a reflective liquid crystal display device, a surface light source, a reflective polarizer, a retardation plate, and a half mirror, wherein the display surface of the reflective liquid crystal display device faces the light-emitting surface of the surface light source, the reflective polarizer is arranged at an angle such that light emitted from the display surface and traveling straight through the surface light source is incident obliquely, and the retardation plate and the half mirror are arranged in this order from the reflective polarizer side in the direction in which the light reflected by the reflective polarizer travels.

[0016] The half mirror may have a curved surface that is concave on the reflective polarizer side.

[0017] The reflective liquid crystal display device may have a linear polarizer, a liquid crystal layer, and a reflective layer in this order from the surface light source side. A retardation film may also be provided between the linear polarizer and the liquid crystal layer.

[0018] The surface light source has a light emitting source and a light guide plate, the light emitting source has first to third light emitting sources, the first light emitting source has a function of emitting red light, the second light emitting source has a function of emitting green light, the third light emitting source has a function of emitting blue light, and the first to third light emitting sources can each have a function of adjusting the emission intensity. A lens may be provided between the surface light source and the reflective polarizing plate.

[0019] Another embodiment of the present invention is an electronic device that includes a semi-transmissive liquid crystal display device, a surface light source, a reflective polarizer, a retardation plate, and a half mirror, in which the surface opposite to the display surface of the semi-transmissive liquid crystal display device faces the light-emitting surface of the surface light source, the reflective polarizer is provided at an angle such that light emitted from the display surface traveling straight ahead is incident obliquely, and the retardation plate and the half mirror are provided in this order from the reflective polarizer side in the traveling direction of the light reflected by the reflective polarizer.

[0020] The half mirror may have a curved surface that is concave on the reflective polarizer side.

[0021] The transflective liquid crystal display device can have, from the reflective polarizer side, a first linear polarizer, a liquid crystal layer, a semi-reflective layer, and a second linear polarizer in this order.

[0022] The semi-reflective layer may be a half-mirror type, or may have a reflective layer and a light-transmitting layer.

[0023] The surface light source has a light source and a light guide plate, and the surface light source has a reflective layer on the surface opposite to the light-emitting surface, and the light source has first to third light sources, the first light source has a function of emitting red light, the second light source has a function of emitting green light, and the third light source has a function of emitting blue light, and the first to third light sources can each have a function of adjusting the light emission intensity.

[0024] Alternatively, the surface light source has a function of transmitting light, the surface light source has a light emitting source and a light guide plate, the light emitting source has first to third light emitting sources, the first light emitting source has a function of emitting red light, the second light emitting source has a function of emitting green light, the third light emitting source has a function of emitting blue light, and the first to third light emitting sources can each have a function of adjusting the light emission intensity.

[0025] The electronic device may have a housing, and the semi-transmissive liquid crystal display device, the surface light source, the reflective polarizer, the retardation film, and the half mirror may be housed in the housing, and a light-receiving window may be provided in an area of ​​the housing overlapping with the surface light source. A lens may be provided between the semi-transmissive liquid crystal display device and the reflective polarizer.

[0026] Another aspect of the present invention is a method for operating an electronic device having a reflective liquid crystal display device or a semi-transmissive liquid crystal display device to which light is incident from a first light source and a second light source, the method comprising: acquiring the illuminance and chromaticity of the light emitted from the first light source using a photometric sensor; changing the illuminance of the second light source so that it has a negative slope with respect to the illuminance; and changing the chromaticity of the light emitted from the second light source according to the chromaticity so that the light incident on the reflective liquid crystal display device or the semi-transmissive liquid crystal display device is white or a color close to that white.

[0027] According to one embodiment of the present invention, an electronic device with high display visibility, an electronic device with low power consumption, a small and lightweight electronic device, a novel electronic device, or a method for operating the electronic device can be provided.

[0028] Note that the description of these effects does not preclude the existence of other effects. One embodiment of the present invention does not necessarily have all of these effects. Effects other than these can be extracted from the description in the specification, drawings, and claims.

[0029] FIG. 1 is a diagram illustrating an electronic device. FIG. 2A is a diagram illustrating a surface light source and a reflective liquid crystal display device. FIGS. 2B to 2E are diagrams illustrating a reflective liquid crystal display device. FIGS. 3A and 3B are diagrams illustrating a polarization state in an optical path. FIGS. 4A and 4B are diagrams illustrating the light utilization efficiency in an optical path. FIG. 5 is a diagram illustrating an electronic device. FIG. 6 is a diagram illustrating a surface light source and a reflective liquid crystal display device. FIGS. 7A and 7B are diagrams illustrating a polarization state in an optical path. FIGS. 8A and 8B are diagrams illustrating the light utilization efficiency in an optical path. FIG. 9 is a diagram illustrating the light utilization efficiency in an optical path. FIG. 10 is a diagram illustrating an electronic device. FIGS. 11A and 11B are diagrams illustrating a surface light source and a semi-transmissive liquid crystal display device. FIGS. 12A and 12B are diagrams illustrating a polarization state in an optical path. FIGS. 13A and 13B are diagrams illustrating the light utilization efficiency in an optical path. FIG. 14 is a diagram illustrating the light utilization efficiency in an optical path. FIGS. 15A and 15B are diagrams illustrating an electronic device. FIG. 16 is a diagram illustrating an electronic device. FIG. 17 is a diagram illustrating a display panel. FIGS. 18A to 18H are diagrams illustrating a display panel. FIGS. 19A and 19B are diagrams illustrating an eyeglass-type device. FIG. 20A is a flowchart illustrating the operation of an electronic device. FIG. 20B is a diagram illustrating a function. FIG. 20C is a diagram illustrating the wavelength distribution of external light and a surface light source. FIG. 21 is a diagram illustrating an example configuration of a display panel. FIG. 22 is a diagram illustrating an example configuration of a display panel. FIG. 23 is a diagram illustrating an example configuration of a display panel. FIG. 24 is a diagram illustrating an example configuration of a display panel. FIG. 25 is a diagram illustrating an example configuration of a display panel. FIGS. 26A and 26B are diagrams illustrating a transistor. FIGS. 27A and 27B are diagrams illustrating a transistor. FIGS. 28A and 28B are diagrams illustrating an example configuration of a display panel.

[0030] The embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and those skilled in the art will readily understand that various modifications in form and detail may be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below. In the configuration of the invention described below, the same parts or parts having similar functions will be designated by the same reference numerals in different drawings, and repeated description thereof may be omitted. Hatching of the same elements constituting the drawings may be omitted or changed as appropriate in different drawings.

[0031] Furthermore, even if a circuit diagram shows a single element, that element may be configured as multiple elements as long as there is no functional problem. For example, multiple transistors operating as switches may be connected in series or parallel. Also, a capacitor may be divided and placed in multiple locations.

[0032] Furthermore, one conductor may have multiple functions, such as wiring, electrode, and terminal, and in this specification, multiple names may be used for the same element. Also, even when elements are shown as being directly connected to each other on a circuit diagram, in reality, the elements may be connected via one or more conductors, and in this specification, such a configuration is also included in the category of direct connection.

[0033] Embodiment 1 In this embodiment, an electronic device according to one embodiment of the present invention will be described.

[0034] One aspect of the present invention is an electronic device that is an optical see-through eyeglass-type device and can be used as an AR device. The electronic device allows a user to view an external scene by superimposing a display on a display panel.

[0035] The electronic device has a reflective liquid crystal display device for displaying information. The reflective liquid crystal display device can receive a portion of the external light entering the electronic device and uses the external light as a light source for display light. Therefore, visibility of the display can be improved even in strong external light. Furthermore, because the external light is used for display, power consumption can be reduced compared to transmissive liquid crystal display devices that use a constant light source and self-luminous organic EL display devices.

[0036] The electronic device also has a separate surface light source as a light source for the reflective liquid crystal display device. The surface light source has light sources for emitting red light (R), green light (G), and blue light (B), and the light emitted from the surface light source can be incident on the reflective liquid crystal display device together with the above-mentioned external light. Since white light is preferable as the light incident on the reflective liquid crystal display device, if the chromaticity of the external light is biased, the chromaticity of the light emitted by the surface light source is adjusted so that the light irradiated on the reflective liquid crystal display device becomes white light. This makes it easy to adjust the chromaticity of the display.

[0037] In this specification, external light refers not only to outdoor light but also to light incident on an electronic device from the outside. Therefore, not only natural light such as sunlight, but also direct and indirect light emitted from light sources (such as electric lights and flames) installed indoors or outdoors can all be called external light.

[0038] 1 is a perspective view illustrating an electronic device of one embodiment of the present invention, and illustrates a display device, a light source, and an optical device included in the electronic device. Note that the shapes of the elements illustrated in FIG. 1 are only examples.

[0039] The electronic device has a reflective liquid crystal display device 20 as a display device, a surface light source 24 as a light source, and a reflective polarizer 30, a retardation plate 41, and a half mirror 42 as optical devices.

[0040] The reflective liquid crystal display device 20 has a liquid crystal layer 21, a linear polarizer 22, and a reflective layer 23. The liquid crystal layer 21 is provided between the linear polarizer 22 and the reflective layer 23, and a user sees light emitted from the linear polarizer 22 in accordance with optical modulation of the liquid crystal. Therefore, in the reflective liquid crystal display device 20, the surface on which the linear polarizer 22 is provided or the surface of the linear polarizer 22 is called the display surface. Note that FIG. 1 shows a simplified illustration of the reflective liquid crystal display device 20, and in an actual configuration, the reflective layer 23 is a pixel electrode and is provided for each pixel. A detailed configuration of the reflective liquid crystal display device will be described later in other embodiments.

[0041] The surface light source 24 is provided on the display surface side of the reflective liquid crystal display device 20. Although Fig. 1 shows an example in which the surface light source 24 and the reflective liquid crystal display device 20 are arranged close to each other, they may also be arranged apart. The surface light source 24 has a high transmittance of visible light, and the user can view the display of the reflective liquid crystal display device 20 through the surface light source 24.

[0042] 2A shows a cross-sectional view illustrating the concept of a reflective liquid crystal display device 20 and a surface light source 24. The surface light source 24 has a light-emitting source 24L at its edge. Light emitted from the light-emitting source 24L propagates through a plate-shaped light guide plate 24P, and is extracted toward a first surface of the light guide plate 24P by changing its direction of travel using tiny triggers 24T distributed throughout the light guide plate 24P. This first surface is called the light-emitting surface of the surface light source. The trigger 24T can be an object with a different refractive index from the light guide plate, an object with high reflectivity, or the surface shape of the light guide plate 24P.

[0043] The light-emitting source 24L has light-emitting sources 24R, 24G, and 24B. For example, an LED element or the like can be used for each of the light-emitting sources 24R, 24G, and 24B. The light-emitting source 24R has a function of emitting red light (R). The light-emitting source 24G has a function of emitting green light (G). The light-emitting source 24B has a function of emitting blue light (B). In other words, the light-emitting source 24L can emit white light obtained by combining RGB. Furthermore, the light emission intensities of the RGB can be individually controlled. This control will be described later in the explanation of the operation of the electronic device.

[0044] Light emitted from the light-emitting surface of the surface light source 24 is incident on the liquid crystal layer 21 via the linear polarizer 22, and is reflected by the reflective layer 23 toward the surface light source 24. The surface light source 24 is also called a front light because it is installed on the display surface side of the reflective liquid crystal display device 20.

[0045] The light emitted from the surface light source 24 is unpolarized (light that vibrates in all directions 360°), and for example, as shown in FIG. 2B, only 0° linearly polarized light passes through the linear polarizer 22 and proceeds to the liquid crystal layer 21.

[0046] Note that, in the following description, the transmission axis of the linear polarizer 22 is assumed to be 0°, but 0° is not an absolute value but a reference value. In other words, the polarization plane of the linearly polarized light that passes through the linear polarizer 22 is treated as 0°. Therefore, for example, 90° linearly polarized light in this embodiment refers to linearly polarized light in which the polarization plane of the linearly polarized light that passes through the linear polarizer 22 is rotated by 90°.

[0047] The light that has entered the liquid crystal layer 21 is subjected to the optical modulation effect of the liquid crystal. The light is reflected by the reflective layer 23, and if it is linearly polarized at 0° before reaching the linear polarizer 22 again, it passes through the linear polarizer 22. The light is then emitted to the outside via the surface light source 24. This state is visually perceived as bright.

[0048] 2C, if the light that has been optically modulated by the liquid crystal is polarized at 90° before reaching the linear polarizer 22 again, the light is absorbed by the linear polarizer 22 and is not emitted to the outside. This state is perceived as darkness.

[0049] Although an example in which a linear polarizer is used in the reflective liquid crystal display device 20 has been described with reference to FIGS. 2B and 2C, a circular polarizer may also be used in the reflective liquid crystal display device 20.

[0050] 2D shows an example in which a retardation film 25 is provided between the liquid crystal layer 21 and the linear polarizer 22. The combination of the linear polarizer 22 and the retardation film 25 acts as a circular polarizer. Although the linear polarizer 22 and the retardation film 25 are shown spaced apart, they may be disposed close to each other.

[0051] The light emitted from the surface light source 24 is unpolarized, and for example, as shown in FIG. 2D, only 0° linearly polarized light passes through the linear polarizer 22 and proceeds to the retardation plate 25 .

[0052] The retardation plate 25 has a function of converting linearly polarized light into circularly polarized light. Here, a λ / 4 plate (¼ wavelength plate) can be used as the retardation plate 25. When the linear polarizer 22 and a λ / 4 plate are overlapped so that the slow axis of the λ / 4 plate is at 45° with respect to the axis of the linearly polarized light emitted from the linear polarizer 22, right-handed circularly polarized light (right-handed circularly polarized light) is obtained. When the linear polarizer 22 and a λ / 4 plate are overlapped so that the slow axis of the λ / 4 plate is at −45° with respect to the axis of the linearly polarized light emitted from the linear polarizer 22, left-handed circularly polarized light (left-handed circularly polarized light) is obtained. In addition, as the opposite function to the above, the retardation plate 25 also has a function of converting circularly polarized light into linearly polarized light.

[0053] Here, an example is used in which 0° linearly polarized light is converted into right-handed circularly polarized light by the retardation plate 25. The right-handed circularly polarized light emitted from the retardation plate 25 travels to the liquid crystal layer 21.

[0054] The light (circularly polarized) that enters the liquid crystal layer 21 is subjected to the optical modulation effect of the liquid crystal and the handedness inversion effect at the reflecting surface. If the light is in a right-handed circularly polarized state before reaching the retardation film 25 again, the light is converted into 0° linearly polarized light by the retardation film 25. The 0° linearly polarized light emitted from the retardation film 25 passes through the linear polarizer 22 and is emitted to the outside via the surface light source 24. This state is visually perceived as bright.

[0055] Alternatively, as shown in Fig. 2E, if light (circularly polarized light) that has been subjected to the effects of optical modulation by the liquid crystal and the handedness inversion at the reflecting surface is again in a left-handed circularly polarized state before reaching the retardation film 25, it is converted into 90° linearly polarized light by the retardation film 25. The 90° linearly polarized light that has been emitted from the retardation film 25 is absorbed by the linear polarizer 22, and the light is not emitted to the outside. This state is visually perceived as dark.

[0056] The reflective polarizer 30 (see FIG. 1 ) is flat and can be provided at an angle such that light emitted from the display surface of the reflective liquid crystal display device 20 and traveling straight through the surface light source 24 is incident obliquely. Specifically, the reflective polarizer 30 is positioned so that the angle of incidence of light emitted perpendicularly from the display surface of the reflective liquid crystal display device 20 is greater than 0° and less than 90°. However, even within this angle range, it is not appropriate if elements of optical equipment or the like block the light path. Therefore, the angle can be set to 20° to 70°, preferably 30° to 60°, more preferably 40° to 50°, and typically 45°. The closer the angle of incidence is to 45°, the easier the optical design, such as element placement, becomes.

[0057] The reflective polarizer 30 reflects linearly polarized light whose vibration direction coincides with the reflection axis, and can transmit linearly polarized light whose vibration direction is perpendicular to the reflection axis. The axis perpendicular to the reflection axis is called the transmission axis. The reflective polarizer 30 is positioned so that light is incident obliquely, so a reflective polarizer that performs the above function at the angle at which it is positioned is used. For example, a wire grid polarizer or a dielectric multilayer film can be used as the reflective polarizer 30.

[0058] The reflective polarizer 30 functions as a beam splitter, and reflects or transmits incident light depending on the polarization state of the light.

[0059] A retardation plate 41 and a half mirror 42 can be provided in this order from the reflective polarizer 30 side in the direction in which light reflected by the reflective polarizer 30 travels. Similar to the combination of the linear polarizer 22 and the retardation plate 25 described above, the combination of the reflective polarizer 30 and the retardation plate 41 also functions as a circular polarizer.

[0060] The half mirror 42 can be made of, for example, a metal film or a dielectric film. The half mirror 42 preferably has positive power to focus the light reflected by the reflective polarizer 30 toward the eye 10. Therefore, the half mirror 42 preferably has a curved surface with a concave surface facing the reflective polarizer 30. The transmittance and reflectance of the half mirror 42 for visible light can be set to 20% or more and 80% or less, where T is the transmittance and (1-T) is the reflectance, and T can be set to, for example, approximately 50%. The transmittance and reflectance of the half mirror 42 for visible light can be appropriately selected depending on the expected illuminance of external light.

[0061] 1 shows an example in which adjacent elements, such as the retarder 41 and the half mirror 42, are arranged close to each other, but this is not limiting. For example, adjacent elements may be arranged apart from each other. Furthermore, a support for the elements may be provided as necessary. Furthermore, other elements, such as lenses, may be provided in the optical path of the electronic device.

[0062] 1 shows an example in which the half mirror 42 and the phase difference plate 41 are disposed close to each other, and therefore the phase difference plate 41 is also shown as having a shape with a concave curved surface, but the phase difference plate 41 may have, for example, a flat plate shape. Note that if an element other than the half mirror 42 of the electronic device can focus light toward the eye 10, the half mirror 42 can also have a flat plate shape.

[0063] To arrange the adjacent elements in close proximity to each other, it is preferable to bond the elements together using an optical adhesive that has high transmittance for the wavelength of light to be used (for example, in the wavelength range of visible light or the wavelength range from blue light to red light) and that does not absorb or birefringence in specific polarized light. Alternatively, instead of bonding, one element may be formed in contact with the other element using a method such as coating. Alternatively, one element and the other element may be arranged in contact with each other without providing an adhesive or the like between them. Alternatively, a gap may be provided between the two.

[0064] A part of the light emitted from the reflective liquid crystal display device 20 and reflected by the reflective polarizer 30 is reflected by the half mirror 42 , passes through the reflective polarizer 30 , and enters the eye 10 .

[0065] Furthermore, external light can be incident on the surface of the half mirror 42 opposite to the retardation plate 41. Of the external light that passes through the retardation plate 41 and reaches the reflective polarizer 30, the polarized light component whose vibration direction coincides with the transmission axis passes through the reflective polarizer 30 and enters the eye 10.

[0066] That is, the light emitted from the display surface of the reflective liquid crystal display device 20 and the external light can be converged by the reflective polarizer 30 and can be incident on the eye 10 .

[0067] Furthermore, of the external light that reaches the reflective polarizer 30, the polarized component whose vibration direction coincides with the reflection axis is reflected by the reflective polarizer 30 and enters the reflective liquid crystal display device 20. That is, in one aspect of the present invention, a portion of the external light taken into the electronic device can be used as a light source for the reflective liquid crystal display device 20.

[0068] Conventional electronic devices often use transmissive liquid crystal display devices or self-luminous organic electroluminescence (EL) display devices to display information. These display devices have a problem in that the light intensity of the information display becomes relatively weak when the illuminance of external light is high, reducing the visibility of the information display. In one aspect of the present invention, a reflective liquid crystal device is used to display information, allowing a portion of the external light entering the electronic device to be incident on the reflective liquid crystal device. Therefore, the higher the illuminance of external light, the stronger the light intensity of the information display, making it possible to clearly view the information display.

[0069] Next, details of the polarization state and the like in the optical path of the electronic device will be described. Figures 3A and 3B are cross-sectional views illustrating the electronic device, showing a portion of the optical path. The electronic device has optical paths LP1, LP2, and LP3.

[0070] Light path LP1 is an optical path that uses the surface light source 24 as a light source and that takes light emitted from the display surface of the reflective liquid crystal display device 20 into the eye 10. Light path LP2 is an optical path that uses external light as a light source and that takes light emitted from the display surface of the reflective liquid crystal display device 20 into the eye 10. Light path LP3 is an optical path that takes external light into the eye 10. Light passing through light path LP1, light passing through light path LP2, and light passing through light path LP3 join together and travel toward the destination (eye 10).

[0071] 3A shows light path LP1, and FIG. 3B shows light paths LP2 and LP3, as well as enlarged views of portions thereof. Also, FIG. 3A and FIG. 3B show a state in which light is emitted from the reflective liquid crystal display device 20 (a state in which light is perceived as bright). In a state in which light is not emitted from the reflective liquid crystal display device 20 (a state in which light is perceived as dark), LP3 is established, but light paths LP1 and LP2 are separated by the display surface of the reflective liquid crystal display device 20.

[0072] In this specification, the optical path of an electronic device refers to the path of light occurring between elements of the electronic device. For example, in an electronic device, if light enters element A from the outside and exits element B, the optical path is the path occurring between element A and element B, and element A can be called the starting point of the optical path and element B the end point of the optical path. Also, if the light source is an element of the electronic device, the light source can be called the starting point of the optical path. Also, the optical path of the electronic device may include the optical path from element B to the destination of the light.

[0073] First, an optical path LP1 for viewing the display of the reflective liquid crystal display device 20 using the surface light source 24 as a light source will be described with reference to FIG. 3A.

[0074] The surface light source 24 is used as a light source, and light emitted from the display surface of the reflective liquid crystal display device 20 passes through the surface light source 24 and reaches the reflective polarizer 30. Here, the reflection axis of the reflective polarizer 30 is set to 0° and the transmission axis is set to 90°. The starting point of the optical path LP1 can be said to be the surface light source 24.

[0075] Since the light emitted from the display surface of the reflective liquid crystal display device 20 is linearly polarized at 0°, it is reflected by the reflective polarizer 30, which has a reflection axis of 0°, and is converted into right-handed circularly polarized light as it passes through the retardation plate 41. The right-handed circularly polarized light emitted from the retardation plate 41 is reflected by the half mirror 42, inverted into left-handed circularly polarized light, and enters the retardation plate 41.

[0076] The left-handed circularly polarized light incident on the retardation plate 41 is converted into 90° linearly polarized light, and passes through the reflective polarizer 30 with a transmission axis of 90° to enter the eye 10. Here, the end point of the optical path LP1 can be said to be the reflective polarizer 30.

[0077] Next, an optical path LP2 for visually recognizing the display of the reflective liquid crystal display device 20 using external light as a light source, and an optical path LP3 for visually recognizing external light (external scene) will be described with reference to FIG. 3B.

[0078] External light incident on the surface of the half mirror 42 opposite to the retardation plate 41 passes through the half mirror 42 and the retardation plate 41 and reaches the reflective polarizer 30. Up to this point, the optical paths LP2 and LP3 share a common path, and it can be said that the starting points of the optical paths LP2 and LP3 are the half mirror 42.

[0079] Here, the external light is unpolarized, and the 90° linearly polarized component whose vibration direction coincides with the transmission axis (90°) of the reflective polarizer 30 is transmitted, while the 0° linearly polarized component whose vibration direction coincides with the reflection axis (0°) of the reflective polarizer 30 is reflected.

[0080] The path of external light passing through the reflective polarizer 30 is an optical path LP3, and the end point of the optical path LP3 is the reflective polarizer 30. The light that has passed through the reflective polarizer 30 can enter the eye 10.

[0081] The path of external light reflected by the reflective polarizer 30 is optical path LP2. The light reflected by the reflective polarizer 30 passes through the surface light source 24 and reaches the reflective liquid crystal display device 20. The light that reaches the reflective liquid crystal display device 20 is 0° linearly polarized light, passes through the 0° linear polarizer, enters the liquid crystal layer 21, and is reflected by the reflective layer while being optically modulated by the liquid crystal. Assuming that the light is viewed as bright, the light passes through the 0° linear polarizer and the surface light source 24 in a 0° linearly polarized state and reaches the reflective polarizer 30.

[0082] Thereafter, the light passes through the same process as the light path LP1, reaches the reflective polarizer 30 again, and enters the eye 10. Therefore, it can be said that the end point of the light path LP2 is the reflective polarizer 30.

[0083] The optical paths LP1, LP2, and LP3 can be merged at the end points or at a path before that, and images formed by the light passing through each optical path can be superimposed. The most significant effect of one aspect of the present invention is that the visibility of the display of the reflective liquid crystal display device 20 is improved by merging the optical paths LP1 and LP2.

[0084] Next, the light utilization efficiency for each optical path will be described with reference to Figures 4A and 4B. Note that the light utilization efficiency described here is for an ideal state, and the surface reflection and absorption of unclear light in each element of the electronic device, as well as the loss of polarization, are ignored here. Furthermore, in the reflective liquid crystal display device 20, the aperture ratio is assumed to be 100%, and losses due to light-shielding layers, etc. are ignored.

[0085] In addition, in the reflective liquid crystal display device 20, the transmittance when unpolarized light is incident on the linear polarizer 22 is 50%, the transmittance of polarized light corresponding to the transmission axis is 100%, and the reflectance of the reflective layer 23 is 100%.

[0086] The reflectance and transmittance of the reflective polarizer 30 when unpolarized light is incident, and the transmittance and reflectance of the half mirror 42 are each set to 50%.

[0087] The transmittance of the surface light source 24 and the retardation plate 41, the reflectance of the polarized light corresponding to the reflection axis of the reflective polarizer 30, and the transmittance of the polarized light corresponding to the transmission axis are each set to 100%.

[0088] First, the light utilization efficiency of the light path LP1 will be described with reference to Fig. 4A. The numerical values ​​shown in the figure indicate relative values ​​at each position when the effective amount of light incident on the reflective LCD device 20 from the surface light source 24 is set to 1a.

[0089] Since the effective light (light amount 1a) emitted from the surface light source 24 to the reflective LCD device 20 is unpolarized, the amount of light transmitted through the linear polarizer 22 is 50%, or 0.5a. Thereafter, the light maintains its amount and is reflected by the reflective layer 23, transmitted through the linear polarizer 22 and the surface light source 24, and reaches the reflective polarizer 30.

[0090] The light is reflected without loss by the reflective polarizer 30, passes through the retardation plate 41, and is reflected by the half mirror 42. At this time, the reflectance of the half mirror 42 is 50%, so the amount of light is attenuated to 0.25a. The light then passes through the retardation plate 41 and the reflective polarizer 30 without loss. Therefore, the amount of light that reaches the eye 10 is 0.25a.

[0091] Next, the light utilization efficiency of the light paths LP2 and LP3 will be described with reference to Fig. 4B. The numerical values ​​shown in the figure indicate relative values ​​at each position when the effective amount of external light incident on the half mirror 42 is set to 1b.

[0092] First, external light (light amount 1b) is incident on the half mirror 42. At this time, the transmittance of the half mirror 42 is 50%, so the light amount is attenuated to 0.5b. Then, the light passes through the phase difference plate 41 and reaches the reflective polarizer 30.

[0093] Since the light transmitted through the retardation plate 41 is unpolarized, the amount of light transmitted through the reflective polarizer 30 is 50%, or 0.25b. In other words, the amount of external light that reaches the eye 10 via the optical path LP3 is 0.25b.

[0094] In addition, the amount of light reflected by the reflective polarizer 30 is also 50%, or 0.25b, and the light passes through the surface light source while maintaining the same amount of light, is reflected by the reflective liquid crystal display device 20, passes through the surface light source again, and reaches the reflective polarizer 30.

[0095] The light is reflected without loss by the reflective polarizer 30, passes through the retardation plate 41, and is reflected by the half mirror 42. At this time, the reflectance of the half mirror 42 is 50%, so the amount of light is attenuated to 0.125b. The light then passes through the retardation plate 41 and the reflective polarizer 30 without loss. Therefore, the amount of light that reaches the eye 10 via the optical path LP2 is 0.125b.

[0096] As a result of the above, the amount of light that reaches the eye 10 as external light (external scene) is 0.25b. Also, the amount of light that reaches the eye 10 as the display of the reflective liquid crystal display device 20 is 0.25a+0.125b.

[0097] Here, under high illuminance such as outdoors, the amount of external light is greater than the amount of light from the surface light source 24 (b>a), so the amount of light reaching the eye 10 as the display on the reflective LCD device 20 is at least greater than 0.25a+0.125a=0.375a. In other words, when the surface light source 24 is the only light source, the amount is 0.25a, ​​so it can be said that the visibility of the display can be improved.

[0098] Furthermore, even under low illuminance, the amount of light reaching the eye 10 as a display on the reflective LCD device 20 can be supplemented by 0.125b of external light, so it may be possible to reduce the amount of light emitted by the surface light source 24. In other words, the power consumption of the surface light source 24 can be reduced.

[0099] Next, electronic devices having different configurations from the electronic device shown in FIG. 1 will be described with reference to FIGS. 5 to 9. FIG.

[0100] 5 is a perspective view illustrating an electronic device of one embodiment of the present invention, which is different from the configuration illustrated in FIG. 1. The electronic device differs from the configuration illustrated in FIG. 1 in the configuration and position of a surface light source, the transmission axis of the linear polarizer 22, and the presence of a linear polarizer 28.

[0101] The surface light source 27 is provided so that its light-emitting surface faces the display surface of the reflective liquid crystal display device 20 via the reflective polarizer 30. The linear polarizer 28 is provided on the light-emitting surface side of the surface light source 27. When the surface light source 27 is placed in the position shown in Figure 5, the display of the reflective liquid crystal display device 20 can be viewed without the surface light source 27.

[0102] Therefore, the surface light source 27 does not require translucency in the thickness direction, and as shown in FIG. 6, a reflective layer 27M can be disposed on the surface opposite the light-emitting surface. Furthermore, the degree of freedom in the placement position, type, and density of the trigger 24T can be increased. Therefore, the light emission intensity can be increased. For example, the surface light source 27 can have a structure equivalent to an edge-type backlight used in transmissive liquid crystal displays, or a direct-type backlight in which light-emitting sources 24L are arranged side by side on a plane. It is preferable that the light-emitting sources 24L have individual RGB light sources, like the surface light source 24.

[0103] Next, details of the polarization state and the like in the optical path of the electronic device shown in Fig. 5 will be described. Fig. 7A and Fig. 7B are cross-sectional views for explaining the electronic device, showing a part of the optical path. Note that the transmission axis of linear polarizer 22 is set at 45°, and the transmission axis of linear polarizer 28 is set at 90°.

[0104] First, an optical path LP1 for viewing the display of the reflective liquid crystal display device 20 using the surface light source 27 as a light source will be described with reference to FIG. 7A.

[0105] Light (unpolarized) emitted from the light-emitting surface of surface light source 27 reaches linear polarizer 28, and the 90° linearly polarized component passes through linear polarizer 28. The light emitted from linear polarizer 28 passes through reflective polarizer 30 with a transmission axis of 90°, and the 45° linearly polarized component passes through linear polarizer 22. The light is then optically modulated by the liquid crystal and reflected by the reflective layer. Assuming that the light is viewed as bright, it passes through liquid crystal layer 21 and linear polarizer 22 and reaches reflective polarizer 30 in a 45° linearly polarized state.

[0106] The reflective polarizer 30, whose reflection axis is 0°, reflects the 0° linearly polarized light component, which is then converted into right-handed circularly polarized light after passing through the retardation plate 41. The right-handed circularly polarized light emitted from the retardation plate 41 is reflected by the half mirror 42, inverted into left-handed circularly polarized light, and enters the retardation plate 41.

[0107] The left-handed circularly polarized light incident on the retardation plate 41 is converted into 90° linearly polarized light, and passes through the reflective polarizer 30 with a transmission axis of 90° to enter the eye 10. Here, the end point of the optical path LP1 can be said to be the reflective polarizer 30.

[0108] Next, an optical path LP2 for visually recognizing the display of the reflective liquid crystal display device 20 using external light as a light source, and an optical path LP3 for visually recognizing external light (external scene) will be described with reference to FIG. 7B.

[0109] External light incident on the surface of the half mirror 42 opposite to the retardation plate 41 passes through the half mirror 42 and the retardation plate 41 and reaches the reflective polarizer 30. Up to this point, the optical paths LP2 and LP3 share a common path, and it can be said that the starting points of the optical paths LP2 and LP3 are the half mirror 42.

[0110] Here, the external light is unpolarized, and the 90° linearly polarized component whose vibration direction coincides with the transmission axis (90°) of the reflective polarizer 30 is transmitted, while the 0° linearly polarized component whose vibration direction coincides with the reflection axis (0°) of the reflective polarizer 30 is reflected.

[0111] The path of external light passing through the reflective polarizer 30 is an optical path LP3, and the end point of the optical path LP3 is the reflective polarizer 30. The light that has passed through the reflective polarizer 30 can enter the eye 10.

[0112] The path of external light reflected by the reflective polarizer 30 is optical path LP2. The light reflected by the reflective polarizer 30 reaches the reflective liquid crystal display device 20. The light that reaches the reflective liquid crystal display device 20 is linearly polarized at 0°, and the 45° linearly polarized component that passes through the linear polarizer 22 is incident on the liquid crystal layer 21, undergoes optical modulation by the liquid crystal, and is folded back by the reflective layer. Assuming that the light is viewed as bright, the light passes through the linear polarizer 22 in a 45° linearly polarized state and reaches the reflective polarizer 30.

[0113] Thereafter, the light passes through the same process as the light path LP1, reaches the reflective polarizer 30 again, and is incident on the eye 10. Therefore, it can be said that the end point of the light path LP2 is the reflective polarizer 30.

[0114] Next, the light utilization efficiency in each optical path will be described using Figures 8A and 8B. Note that the light utilization efficiency described here is for an ideal state, and the surface reflection and absorption of unclear light in each element of the electronic device, as well as the collapse of polarization, are ignored here. Also, in the reflective liquid crystal display device 20, the aperture ratio is assumed to be 100%, and losses due to light-shielding layers, etc. are ignored. Also, the reflectance and transmittance of each element are assumed to be the same values ​​as those used in the description of Figures 4A and 4B, and differences will be explained accordingly.

[0115] First, the light utilization efficiency of the light path LP1 will be described with reference to Fig. 8A. The numerical values ​​shown in the figure indicate relative values ​​at each position when the effective amount of light incident on the linear polarizer 28 from the surface light source 27 is set to 1a.

[0116] Since the effective light (light amount 1a) emitted from the surface light source 27 to the linear polarizer 28 is unpolarized, the amount of light transmitted through the linear polarizer 28 is 50%, or 0.5a. Thereafter, the light maintains its amount and transmits through the reflective polarizer 30, reaching the linear polarizer 22 of the reflective LCD device 20.

[0117] The light that reaches the linear polarizer 22 is linearly polarized at 90°, and the transmission axis of the linear polarizer 22 is 45°, so the amount of light that is transmitted is the product of 0.5, which corresponds to the decomposition component of the vector, and the amount of incident light. In other words, since the amount of 90° linearly polarized light that is incident on the linear polarizer 22 is 0.5a, the amount of light that is transmitted through the linear polarizer 22 is 0.25a.

[0118] The light that reaches the reflective polarizer 30 is linearly polarized at 45°, and the reflection axis of the reflective polarizer 30 is 0°, so the amount of reflected light is the product of 0.5, which corresponds to the decomposition component of the vector, and the amount of incident light. In other words, since the amount of 45° linearly polarized light incident on the reflective polarizer 30 is 0.25a, ​​the amount of light reflected by the reflective polarizer 30 is 0.125a.

[0119] The light reflected by the reflective polarizer 30 passes through the retardation plate 41 and is reflected by the half mirror 42. At this time, the reflectance of the half mirror 42 is 50%, so the amount of light is attenuated to 0.0625a. The light then passes through the retardation plate 41 and the reflective polarizer 30 without loss. Therefore, the amount of light reaching the eye 10 is 0.0625a.

[0120] Next, the light utilization efficiency of the light paths LP2 and LP3 will be described with reference to Fig. 8B. The numerical values ​​shown in the figure indicate relative values ​​at each position when the effective amount of external light incident on the half mirror 42 is set to 1b.

[0121] First, external light (light amount 1b) is incident on the half mirror 42. At this time, the transmittance of the half mirror 42 is 50%, so the light amount is attenuated to 0.5b. Then, the light passes through the phase difference plate 41 and reaches the reflective polarizer 30.

[0122] Since the light transmitted through the retardation plate 41 is unpolarized, the amount of light transmitted through the reflective polarizer 30 is 50%, or 0.25b. In other words, the amount of external light that reaches the eye 10 via the optical path LP3 is 0.25b.

[0123] Furthermore, the amount of light reflected by the reflective polarizer 30 is also 50%, or 0.25b, and reaches the linear polarizer 22 of the reflective liquid crystal display device 20 .

[0124] The light that reaches the linear polarizer 22 is linearly polarized at 0°, and the transmission axis of the linear polarizer 22 is at 45°, so the amount of light that is transmitted is the product of 0.5, which corresponds to the decomposition component of the vector, and the amount of incident light. In other words, since the amount of 0° linearly polarized light that is incident on the linear polarizer 22 is 0.25b, the amount of light that is transmitted through the linear polarizer 22 is 0.125b.

[0125] The light that reaches the reflective polarizer 30 is linearly polarized at 45°, and the reflection axis of the reflective polarizer 30 is 0°, so the amount of reflected light is the product of 0.5, which corresponds to the decomposition component of the vector, and the amount of incident light. In other words, since the amount of 45° linearly polarized light incident on the reflective polarizer 30 is 0.125b, the amount of light reflected by the reflective polarizer 30 is 0.0625b.

[0126] The light reflected by the reflective polarizer 30 passes through the retardation plate 41 and is reflected by the half mirror 42. At this time, the reflectance of the half mirror 42 is 50%, so the amount of light is attenuated to 0.03125b. The light then passes through the retardation plate 41 and the reflective polarizer 30 without loss. Therefore, the amount of light that reaches the eye 10 via the optical path LP2 is 0.03125b.

[0127] As a result of the above, the amount of light that reaches the eye 10 as external light (external scene) is 0.25b. Also, the amount of light that reaches the eye 10 as the display of the reflective liquid crystal display device 20 is 0.0625a+0.03125b.

[0128] Here, under high illuminance such as outdoors, the amount of external light is greater than the amount of light from the surface light source 27 (b>a), so the amount of light reaching the eye 10 as the display on the reflective LCD device 20 is at least greater than 0.0625a + 0.03125a = 0.09375a. In other words, when the surface light source 27 is the only light source, the amount is 0.0625a, so it can be said that the visibility of the display can be improved.

[0129] Furthermore, even under low illuminance, the amount of light reaching the eye 10 as a display on the reflective LCD device 20 can be supplemented by 0.03125b of external light, so it may be possible to reduce the amount of light emitted by the surface light source 27. In other words, the power consumption of the surface light source 27 can be reduced.

[0130] 9, the surface light source 24 described in Fig. 2A can also be used as the surface light source. In this case, since the surface light source 24 can transmit light in the thickness direction, external light can be incident on the surface opposite to the light-emitting surface and used as display light for the reflective liquid crystal display device 20.

[0131] 9 can be said to be the same as LP1. Therefore, referring to the explanations of Fig. 7A and Fig. 8A, if the effective amount of light that passes through the surface light source 24 and enters the linear polarizer 28 is 1c, the amount of display light from the reflective liquid crystal display device 20 that reaches the eye 10 is 0.0625c.

[0132] 8A, 8B, and 9, the amount of light that reaches the eye 10 as external light (external scene) is 0.25b. Also, the amount of light that reaches the eye 10 as the display of the reflective liquid crystal display device 20 is 0.0625a + 0.03125b + 0.0625c.

[0133] Here, under high illuminance, the amount of external light is greater than the amount of light from the surface light source 27 (b>a, c>a), so the amount of light reaching the eye 10 as the display on the reflective LCD device 20 is at least greater than 0.0625a + 0.03125a + 0.0625a = 0.15625a. In other words, when the surface light source 27 is the only light source, the amount is 0.0625a, so it can be said that the visibility of the display can be improved.

[0134] Furthermore, even under low illuminance, the amount of light reaching the eye 10 as a display on the reflective LCD device 20 can be supplemented by 0.03125b + 0.0625c of external light, so it may be possible to reduce the amount of light from the surface light source 27. In other words, the power consumption of the surface light source 27 can be reduced.

[0135] Next, electronic devices having different configurations from those shown in FIGS. 1 and 2 will be described with reference to FIGS. 10 to 14. FIG.

[0136] 10 is a perspective view illustrating an electronic device of one embodiment of the present invention, which is different from the electronic device illustrated in FIGS. 1 and 2. The electronic device differs from the electronic device illustrated in FIGS. 1 and 2 in that a semi-transmissive liquid crystal display device 20t is used.

[0137] The transflective liquid crystal display device 20t includes a liquid crystal layer 21, a linear polarizer 22, a semi-transmissive / semi-reflective layer 23h, and a linear polarizer 26. The liquid crystal layer 21 is disposed between the linear polarizer 22 and the semi-transmissive / semi-reflective layer 23h. A user visually recognizes light emitted from the linear polarizer 22 in response to optical modulation of the liquid crystal. Therefore, in the transflective liquid crystal display device 20t, the surface on which the linear polarizer 22 is disposed or the surface of the linear polarizer 22 is referred to as the display surface. A linear polarizer 26 is disposed on the surface opposite the display surface. Note that FIG. 10 shows a simplified illustration of the transflective liquid crystal display device 20t; in an actual configuration, the semi-transmissive / semi-reflective layer 23h is a pixel electrode provided for each pixel. A detailed configuration of the transflective liquid crystal display device will be described later in other embodiments.

[0138] The surface light source 27 can be provided in a position where its light-emitting surface faces the linear polarizer 26. The semi-transmissive liquid crystal display device 20t can operate both as a transmissive liquid crystal display device using the surface light source 27 as a light source and as a reflective liquid crystal display device using external light as a light source.

[0139] FIG. 11A shows a cross-sectional view illustrating the concept of the semi-transmissive liquid crystal display device 20t and the surface light source 27. For example, a half mirror with a transmittance and a reflectance of 50% can be used for the semi-transmissive / semi-reflective layer 23h. Therefore, when the illuminance of external light is sufficiently high, the device can be operated as a reflective liquid crystal display device. In this case, the surface light source 27 may be in an off state. Furthermore, when the illuminance of external light is low, the device can be operated as a transmissive liquid crystal display device.

[0140] The semi-transmitting / semi-reflective layer 23h is not limited to the half-mirror type described above, and may have a configuration including a reflective layer 23r and a light-transmitting layer 23t, as shown in Fig. 11B. The region provided with the reflective layer 23r functions as a reflective liquid crystal display device, and the region provided with the light-transmitting layer 23t functions as a transmissive liquid crystal display device. The light-transmitting layer 23t has a light-transmitting conductive layer, which functions as a pixel electrode.

[0141] Next, details of the polarization state and other aspects of the optical paths of the electronic device shown in Fig. 10 will be described. Fig. 12A and Fig. 12B are cross-sectional views illustrating the electronic device, showing parts of the optical paths. The electronic device has optical paths LP1, LP2, and LP3.

[0142] 12A, a description will be given of an optical path LP1 for viewing a display on a transflective liquid crystal display device 20t using a surface light source 27 as a light source. The transmission axis of the linear polarizer 26 is set to 0°.

[0143] The light (unpolarized) emitted from the light-emitting surface of the surface light source 27 reaches the linear polarizer 26, and the 0° linearly polarized light component passes through the linear polarizer 26. The light emitted from the linear polarizer 26 passes through the semi-transmissive / semi-reflective layer 23h, and, assuming that the light is perceived as bright, passes through the liquid crystal layer 21 and the linear polarizer 22. Here, the starting point of the optical path LP1 can be said to be the surface light source 27.

[0144] The light that reaches the reflective polarizer 30 is linearly polarized at 0°, so it is reflected by the reflective polarizer 30, whose reflection axis is 0°, and is converted into right-handed circularly polarized light as it passes through the retardation plate 41. The right-handed circularly polarized light that has emerged from the retardation plate 41 is reflected by the half mirror 42, is inverted to left-handed circularly polarized light, and enters the retardation plate 41.

[0145] The left-handed circularly polarized light incident on the retardation plate 41 is converted into 90° linearly polarized light, and passes through the reflective polarizer 30 with a transmission axis of 90° to enter the eye 10. Here, the end point of the optical path LP1 can be said to be the reflective polarizer 30.

[0146] Next, an optical path LP2 for visually recognizing the display of the semi-transmissive liquid crystal display device 20t using external light as a light source, and an optical path LP3 for visually recognizing external light (external scene) will be described with reference to FIG. 12B.

[0147] External light incident on the surface of the half mirror 42 opposite to the retardation plate 41 passes through the half mirror 42 and the retardation plate 41 and reaches the reflective polarizer 30. Up to this point, the optical paths LP2 and LP3 share a common path, and it can be said that the starting points of the optical paths LP2 and LP3 are the half mirror 42.

[0148] Here, the external light is unpolarized, and the 90° linearly polarized component whose vibration direction coincides with the transmission axis (90°) of the reflective polarizer 30 is transmitted, while the 0° linearly polarized component whose vibration direction coincides with the reflection axis (0°) of the reflective polarizer 30 is reflected.

[0149] The path of external light passing through the reflective polarizer 30 is an optical path LP3, and the end point of the optical path LP3 is the reflective polarizer 30. The light that has passed through the reflective polarizer 30 can enter the eye 10.

[0150] The path of the external light reflected by the reflective polarizer 30 is optical path LP2. The light reflected by the reflective polarizer 30 reaches the semi-transmissive liquid crystal display device 20t. The light reaching the semi-transmissive liquid crystal display device 20t is linearly polarized at 0°, passes through the linear polarizer 22, and is reflected by the semi-transmissive / semi-reflective layer 23h while being optically modulated by the liquid crystal. Assuming that the light is viewed as bright, the light passes through the linear polarizer 22 in a state of linear polarization at 0° and reaches the reflective polarizer 30.

[0151] Thereafter, the light passes through the same process as the light path LP1, reaches the reflective polarizer 30 again, and is incident on the eye 10. Therefore, it can be said that the end point of the light path LP2 is the reflective polarizer 30.

[0152] Next, the light utilization efficiency in each optical path will be described using Figures 13A and 13B. Note that the light utilization efficiency described here is ideal, and the surface reflection and absorption of unclear light in each element of the electronic device, as well as the breakdown of polarization, are ignored here. Furthermore, in the semi-transmissive liquid crystal display device 20t, the aperture ratio is assumed to be 100%, and losses due to light-shielding layers, etc. are ignored. Furthermore, the reflectance and transmittance of each element are assumed to be the same as those used in the description of Figures 4A and 4B, and the transmittance and reflectance of the semi-transmissive / semi-reflective layer 23h are assumed to be 50%, respectively.

[0153] First, the light utilization efficiency of the light path LP1 will be described with reference to Fig. 13A. The numerical values ​​shown in the figure indicate relative values ​​at each position when the effective amount of light incident on the linear polarizer 26 from the surface light source 27 is set to 1a.

[0154] Since the effective light (light amount 1a) emitted from the surface light source 27 to the linear polarizer 26 is unpolarized, the amount of light that passes through the linear polarizer 26 is 0.5a, which is 50%. Thereafter, the amount of light is attenuated to 0.25a by the semi-transmissive / semi-reflective layer 23h, which has a transmittance of 50%, and reaches the reflective polarizer 30.

[0155] The light reflected by the reflective polarizer 30 passes through the retardation plate 41 and is reflected by the half mirror 42. At this time, the reflectance of the half mirror 42 is 50%, so the amount of light is attenuated to 0.125a. The light then passes through the retardation plate 41 and the reflective polarizer 30 without loss. Therefore, the amount of light reaching the eye 10 is 0.125a.

[0156] Next, the light utilization efficiency of the light paths LP2 and LP3 will be described with reference to Fig. 13B. The numerical values ​​shown in the figure indicate relative values ​​at each position when the effective amount of external light incident on the half mirror 42 is set to 1b.

[0157] First, external light (light amount 1b) is incident on the half mirror 42. At this time, the transmittance of the half mirror 42 is 50%, so the light amount is attenuated to 0.5b. Then, the light passes through the phase difference plate 41 and reaches the reflective polarizer 30.

[0158] Since the light transmitted through the retardation plate 41 is unpolarized, the amount of light transmitted through the reflective polarizer 30 is 50%, or 0.25b. In other words, the amount of external light that reaches the eye 10 via the optical path LP3 is 0.25b.

[0159] Furthermore, the amount of light reflected by the reflective polarizer 30 is also 50%, or 0.25b, and reaches the linear polarizer 22 of the transflective liquid crystal display device 20t.

[0160] The light that reaches the linear polarizer 22 is linearly polarized at 0°, passes through the linear polarizer 22, and is reflected by the semi-transmissive and semi-reflective layer 23h. At this time, since the reflectance of the semi-transmissive and semi-reflective layer 23h is 50%, the amount of light is attenuated to 0.125b before reaching the reflective polarizer 30.

[0161] The light reflected by the reflective polarizer 30 passes through the retardation plate 41 and is reflected by the half mirror 42. At this time, the reflectance of the half mirror 42 is 50%, so the amount of light is attenuated to 0.0625b. The light then passes through the retardation plate 41 and the reflective polarizer 30 without loss. Therefore, the amount of light that reaches the eye 10 via the optical path LP3 is 0.0625b.

[0162] As a result, the amount of light reaching the eye 10 as external light (external scene) is 0.25b. The amount of light reaching the eye 10 as the display of the semi-transmissive liquid crystal display device 20t is 0.125a+0.0625b.

[0163] Here, under high illuminance, the amount of external light is greater than the amount of light from the surface light source 27 (b>a), and therefore the amount of light that reaches the eye 10 as the display of the semi-transmissive liquid crystal display device 20t is at least greater than 0.125a + 0.0625a = 0.1875a. In other words, when the surface light source 27 is the only light source, the amount is 0.125a, and therefore it can be said that the visibility of the display can be improved.

[0164] Furthermore, even under low illuminance, the amount of light reaching the eye 10 as a display on the reflective LCD device 20 can be supplemented by 0.0625b of external light, so it may be possible to reduce the amount of light from the surface light source 27. In other words, the power consumption of the surface light source 27 can be reduced.

[0165] 14, the surface light source 24 described in Fig. 2A can also be used as the surface light source. In this case, since the surface light source 24 can transmit light in the thickness direction, external light can be incident from the surface opposite to the light-emitting surface and can be used as display light for the transflective liquid crystal display device 20t.

[0166] 14 can be said to be the same as LP1. Therefore, referring to the descriptions of Fig. 12A and Fig. 13A, if the effective amount of light that passes through the surface light source 24 and enters the linear polarizer 26 is 1c, the amount of display light of the semi-transmissive liquid crystal display device 20t that reaches the eye 10 is 0.125c.

[0167] 13A, 13B, and 14, the amount of light that reaches the eye 10 as external light (external scene) is 0.25b. Also, the amount of light that reaches the eye 10 as the display of the semi-transmissive liquid crystal display device 20t is 0.125a + 0.0625b + 0.125c.

[0168] Here, under high illuminance, the amount of external light is greater than the amount of light from the surface light source 27 (b>a, c>a), so the amount of light that reaches the eye 10 as the display of the semi-transmissive liquid crystal display device 20t is at least greater than 0.125a + 0.0625a + 0.125a = 0.3125a. In other words, when the surface light source 27 is the only light source, the amount is 0.125a, so it can be said that the visibility of the display can be improved.

[0169] Furthermore, even under low illuminance, the amount of light reaching the eye 10 as a display on the reflective LCD device 20 can be supplemented by 0.0625b + 0.125c from external light, so it may be possible to reduce the amount of light emitted by the surface light source 27. In other words, the power consumption of the surface light source 27 can be reduced.

[0170] 1, 5, and 10 may use a configuration in which the shape or position of one or more elements is changed in consideration of being incorporated into the housing of the electronic device, etc. In such a case, another element may be added so that the light passing through the optical path LP1 and the optical path LP2 forms an image at the same position.

[0171] For example, in the electronic device shown in Fig. 1, a lens 31 can be provided between the surface light source 24 and the reflective polarizer 30 as shown in Fig. 15A. In addition, in the electronic device shown in Fig. 5, a lens 31 can be provided between the reflective liquid crystal display device 20 and the reflective polarizer 30 as shown in Fig. 15B. Alternatively, a lens 32 can be provided between the reflective polarizer 30 and the linear polarizer 28. In addition, in the electronic device shown in Fig. 10, a lens 31 can be provided between the semi-transmissive liquid crystal display device 20t and the reflective polarizer 30 as shown in Fig. 16.

[0172] It is preferable not to provide a lens between the reflective polarizer 30 and the retardation film 41. If a lens is provided in this location, it is possible to adjust the optical paths LP1 and LP2, but it will also cause unintended changes to the optical path LP3. However, a lens 33 can be provided outside the half mirror 42. Because this location does not affect the optical paths LP1 and LP2, it functions as a diopter adjustment lens that adjusts only the external light that is taken in. Furthermore, as a lens that also serves as a diopter adjustment, a lens 34 can be provided on the light exit side after the optical paths LP1, LP2, and LP3 converge. Furthermore, a lens that also serves as a diopter adjustment can be provided between the reflective polarizer 30 and the retardation film 41.

[0173] 15A, 15B, and 16 show examples in which a biconvex lens is used for each lens, but this is not limiting. For example, each lens may be composed of a plurality of biconvex lenses. Furthermore, each lens may be a plano-convex lens. Alternatively, each lens may be composed of a combination of lenses selected from biconvex lenses, plano-convex lenses, biconcave lenses, plano-concave lenses, convex meniscus lenses, and concave meniscus lenses. Furthermore, each lens is not limited to a spherical lens, and may also be an aspherical lens. Furthermore, each lens may have a different shape.

[0174] 17 is a block diagram illustrating a display device corresponding to the reflective liquid crystal display device 20 or the semi-transmissive liquid crystal display device 20t included in an electronic device of one embodiment of the present invention. The display device includes a pixel array 74, a circuit 75, and a circuit 76. The pixel array 74 includes pixels 70 arranged in the column and row directions.

[0175] The pixel 70 can have a plurality of sub-pixels 71. The sub-pixels 71 have liquid crystal elements and have the function of emitting light for display using light incident from a light source. By providing the sub-pixels 71 with color filters such as R (red), G (green), and B (blue), a full-color display can be achieved.

[0176] The circuit 75 and the circuit 76 are driver circuits for driving the sub-pixel 71. The circuit 75 can function as a source driver circuit, and the circuit 76 can function as a gate driver circuit. The circuits 75 and 76 can be, for example, shift register circuits.

[0177] The reflective liquid crystal display device 20 may be divided into a plurality of regions vertically and horizontally, and pixels may be driven for each divided region.

[0178] 18A , for example, the circuits 75 and 76 can be separately arranged below the pixel array 74. In this case, the reflective liquid crystal display device 20 has a laminated structure of layers 77 and 78, and multiple circuits 75 and multiple circuits 76 are provided on the layer 77, with the pixel array 74 being provided on the layer 78 so as to overlap them.

[0179] By dividing the circuit 75 and the circuit 76, the pixel array 74 can be driven for each divided area. For example, the pixel array 74 can be operated at different frame rates in parts. The pixel array 74 can be displayed at different resolutions in parts, and can also be made compatible with foveated rendering.

[0180] Furthermore, by providing the driver circuit below the pixel array 74, the wiring length can be shortened and the wiring capacitance can be reduced. This allows for high-speed operation with low power consumption. Furthermore, the reflective LCD device 20 can have a narrow frame.

[0181] 18A are merely examples and may be changed as appropriate. Part of the circuit 75 and the circuit 76 may be formed in the same layer as the pixel array 74. The layer 77 may also include circuits such as a memory circuit, an arithmetic circuit, and a communication circuit.

[0182] In this structure, for example, the layer 77 is provided on a single crystal silicon substrate, the circuits 75 and 76 are formed using transistors having silicon in their channel formation regions (hereinafter referred to as Si transistors), and the pixel circuits included in the pixel array 74 provided in the layer 78 are formed using transistors having metal oxide in their channel formation regions (hereinafter referred to as OS transistors). The OS transistor can be formed using a thin film and can be stacked on the Si transistor.

[0183] 18B , a structure may be adopted in which a layer 79 including an OS transistor is provided between the layer 77 and the layer 78. The layer 79 may include an OS transistor that forms part of a pixel circuit included in the pixel array 74. Alternatively, the layer 79 may include an OS transistor that forms part of the circuit 75 and the circuit 76. Alternatively, the layer 77 may include an OS transistor that forms part of a circuit such as a memory circuit, an arithmetic circuit, or a communication circuit.

[0184] The shape of the top surface of the reflective LCD device 20 is not limited to a rectangle, but may be a circle as shown in Fig. 18C, or a polygon such as an octagon as shown in Fig. 18D.

[0185] In the semi-transmissive liquid crystal display device 20t, since light passing through the layer on which the pixel array 74 is provided is also utilized, it is preferable to provide the pixel array 74, circuits 75, and circuits 76 on a layer 80, as shown in Fig. 18E. It is preferable that the layer 80 includes a support substrate such as a glass substrate, a quartz substrate, or a resin substrate that has a high transmittance to visible light.

[0186] Although FIG. 18E shows an example in which the circuits 75 and 76 are provided as a monolithic type, as shown in FIG. 18F, either or both of the circuits 75 and 76 may be provided by mounting on an IC chip.

[0187] The shape of the top surface of the transflective liquid crystal display device 20t is not limited to a rectangle, but may be a circle as shown in Fig. 18G, or a polygon such as an octagon as shown in Fig. 18H. The reflective liquid crystal display device 20 can also be formed in the shapes shown in Figs. 18E to 18H.

[0188] Fig. 19A is a diagram showing an example of an eyeglass-type device having the configuration shown in Fig. 1. Here, the combination of the display device, light source, and optical device shown in Fig. 1 is shown by dashed lines as a display unit 92. The eyeglass-type device has two sets of display units 92 stored in a housing 90.

[0189] The front surface of the housing 90 has a light-transmitting portion 96 through which external light is introduced into the display unit 92. The user can visually recognize the light from the display device of the display unit 92 superimposed on the external light. The display device can display virtual information. The user can visually recognize the scene superimposed on the display, and can experience augmented reality in which virtual information is superimposed on reality.

[0190] 19B is a diagram showing an example of an eyeglass-type device having the configuration shown in Fig. 10, in which a configuration is applied that allows external light to be introduced from the side opposite to the light-emitting surface of the surface light source 24 shown in Fig. 14. Here, the combination of the display device, light source, and optical device shown in Fig. 10 is shown by dashed lines as a display unit 95. The eyeglass-type device has two display units 95.

[0191] A light-receiving window 93 is provided at the top of the housing 90 so as to overlap with the surface light source 24. By taking in external light through the light-receiving window 93, the external light can be used as a light source for the semi-transmissive liquid crystal display device, thereby improving the visibility of the display under high illuminance.

[0192] An input terminal and an output terminal may be provided on the housing 90 or the band 91. The input terminal can be connected to a cable for supplying a video signal from a video output device or the like, or for supplying power for charging a battery provided within the housing 90. The output terminal functions as, for example, an audio output terminal, and can be connected to earphones, headphones, etc. Note that if the device is configured to be able to output audio data via wireless communication, or if audio is output from an external video output device, the audio output terminal need not be provided.

[0193] Furthermore, a wireless communication module and a storage module may be provided inside the housing 90 or the band 91. The wireless communication module allows wireless communication, and the content to be viewed can be downloaded and stored in the storage module. This allows the user to view the downloaded content offline. It is also possible to connect to the Internet and retrieve information about the scene being viewed.

[0194] A line-of-sight detection sensor may also be provided inside the housing 90. For example, operation buttons such as power on, power off, sleep, volume adjustment, channel change, menu display, selection, decision, and back, as well as operation buttons such as video playback, stop, pause, fast forward, and fast rewind, can be displayed, and each operation can be performed by visually recognizing the operation button.

[0195] Also, an optical sensor 94 for sensing, detecting, or measuring the illuminance and chromaticity of external light is provided within the housing 90. A photodiode combined with a color filter or the like can be used as the optical sensor 94. In the configuration shown in Fig. 19A, the optical sensor 94 can be provided near the light-transmitting portion 96. In the configuration shown in Fig. 19B, the optical sensor 94 can be provided in two locations: near the light-transmitting portion 96 and near the light-receiving window 93.

[0196] As described above, in the electronic device of one embodiment of the present invention, the visibility of a display under high illuminance can be improved by using light emitted from a surface light source and external light as display light for a liquid crystal display device. Note that the illuminance of external light is not constant, so it is preferable to improve the visibility of the display by adjusting the intensity of light emitted from the surface light source. Furthermore, since the chromaticity of external light is not constant, it is preferable to adjust the chromaticity of light emitted from the surface light source so that the light incident on the liquid crystal display device approaches white light. By introducing white light into the liquid crystal display device, the chromaticity of the display can be easily adjusted.

[0197] That is, it is preferable to adjust the light emission intensity and chromaticity of the surface light source according to the illuminance and chromaticity of the external light.An example of the control operation of the surface light source will be described with reference to the flowchart shown in FIG.

[0198] First, in step 1 (S1), photometry of external light is performed using the optical sensor 94 to measure the illuminance and chromaticity of the external light. Next, in step 2 (S2), it is determined whether or not to use a surface light source in combination. In order to ensure a certain level of visibility of the display of the liquid crystal display device, it is sufficient that the illuminance of light incident on the liquid crystal display device from the light source (surface light source and external light) is at least a certain level.

[0199] Therefore, for example, as shown in Figure 20B, it is preferable to use a function in which the surface light source illuminance has a negative slope with respect to the ambient light illuminance, and to control the illuminance of the surface light source to lower when the ambient light illuminance is high and to increase when the ambient light illuminance is low. By performing such control, it is possible to ensure a certain level of visibility of the display and reduce the power consumption of the surface light source. Furthermore, because the chromaticity of ambient light varies depending on the environment in which the electronic device is used, it is preferable to adjust the chromaticity using a surface light source regardless of the ambient light illuminance.

[0200] Therefore, in S2, if the illuminance and chromaticity of the external light are measured and the chromaticity is biased even if the illuminance is sufficient, a determination is made to use a surface light source in addition. In this case, the process proceeds to step 3 (S3) and turns on the surface light source.

[0201] For example, as shown on the left side of Figure 20C, when outdoors in the evening, the distribution of red light (R) may be greater than that of green light (G) and blue light (B). When there is a bias in the wavelength distribution like this, it can be said that the external light is far from white light.

[0202] In such a case, as shown on the right side of Figure 20C, the wavelength distribution of the light emitted by the surface light source is controlled to make the light combined with the external light closer to white light or a color close to that. For example, it is preferable to control the color temperature so that the color is in the range of 3500K to 6500K. By making the light incident on the liquid crystal display device white light, it is possible to easily adjust the chromaticity of the display. To perform such control, it is preferable that the surface light source has RGB light-emitting sources, and the emission intensity of each color can be controlled, as shown in Figure 2A, etc.

[0203] If the illuminance of the external light is sufficiently high and the chromaticity is substantially in the range of white, the process proceeds to step 4 (S4) and the surface light source can be turned off.

[0204] After S3 or S4, in step 5 (S5), it is determined whether or not to continue using the electronic device. If the use of the electronic device is to be continued, the process returns to S1, and if not, the process ends.

[0205] By using one embodiment of the present invention for a glasses-type device, the electronic device can be small, thin, low in power consumption, and highly reliable.

[0206] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes and examples described in this specification.

[0207] In this embodiment, a configuration example of a liquid crystal display device that can be applied to an electronic device of one embodiment of the present invention will be described. The liquid crystal display device is a high-resolution display panel, and is particularly suitable for use as a display portion of a VR device such as a head-mounted display and a wearable device that can be worn on the head, such as a glasses-type AR device.

[0208] 21 shows a perspective view of a display module 280. The display module 280 has a display panel 200A and an FPC 290. Note that the display panel of the display module 280 is not limited to the display panel 200A, and may be any of the other display panels described below.

[0209] The display module 280 has a substrate 291 and a substrate 292. The display module 280 has a display portion 281. The display portion 281 is a region for displaying an image, and has a liquid crystal element between the substrate 291 and the substrate 292.

[0210] 22 shows a cross-sectional view of a display panel 200A that can be used as the display module 280. The display panel 200A has a substrate 301, a liquid crystal element 547, a capacitor 240, and a transistor 310. The substrate 301 corresponds to the substrate 291 in FIG. 21. Note that the configuration of a reflective liquid crystal display device is shown here as an example.

[0211] The transistor 310 has a channel formation region in a substrate 301. The substrate 301 can be, for example, a semiconductor substrate such as a single crystal silicon substrate. The transistor 310 includes a part of the substrate 301, a conductive layer 311, a low-resistance region 312, an insulating layer 313, and an insulating layer 314. The conductive layer 311 functions as a gate electrode. The insulating layer 313 is located between the substrate 301 and the conductive layer 311 and functions as a gate insulating layer. The low-resistance region 312 is a region in which the substrate 301 is doped with impurities and functions as one of a source and a drain. The insulating layer 314 is provided to cover a side surface of the conductive layer 311.

[0212] An element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301 .

[0213] In addition, an insulating layer 261 is provided to cover the transistor 310 , and a capacitor 240 is provided over the insulating layer 261 .

[0214] The capacitor 240 has a conductive layer 241, a conductive layer 245, and an insulating layer 243 located therebetween. The conductive layer 241 functions as one electrode of the capacitor 240, the conductive layer 245 functions as the other electrode of the capacitor 240, and the insulating layer 243 functions as a dielectric of the capacitor 240.

[0215] The conductive layer 241 is provided over the insulating layer 261 and is buried in the insulating layer 254. The conductive layer 241 is electrically connected to one of the source and drain of the transistor 310 by a plug 271 buried in the insulating layer 261. The insulating layer 243 is provided to cover the conductive layer 241. The conductive layer 245 is provided in a region overlapping with the conductive layer 241 with the insulating layer 243 interposed therebetween.

[0216] An insulating layer 255 is provided to cover the capacitor 240, and a liquid crystal element 547 is provided over the insulating layer 255. The liquid crystal element 547 has a structure in which a liquid crystal layer sandwiched between a pair of alignment films (alignment films 545a and 545b) is sandwiched between a pair of electrodes. A pixel electrode 541, which is one electrode of the liquid crystal element, is electrically connected to the capacitor 240 and the transistor 310 via a plug 256. The pixel electrode 541 can be used as a reflective layer.

[0217] The pixel electrode 541 is preferably formed from a material with high visible light reflectance. For example, metal materials such as aluminum, gold, platinum, silver, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, or palladium, or alloys containing these metal materials, can be used. Lanthanum, neodymium, germanium, or the like may also be added to the above metal materials or alloys of the above metal materials. Alloys containing titanium, nickel, or neodymium and aluminum (aluminum alloys) may also be used. Alloys containing copper, palladium, magnesium, and silver may also be used. Silver-copper alloys are preferred because of their high heat resistance. Furthermore, stacking a metal film or metal oxide film in contact with an aluminum film or aluminum alloy film can suppress oxidation. Examples of materials for such metal films and metal oxide films include titanium and titanium oxide. A conductive film that transmits visible light and a film made of a metal material may also be stacked. For example, a stacked film of silver and indium tin oxide, or a stacked film of an alloy of silver and magnesium and indium tin oxide, can be used.

[0218] As the liquid crystal element 547, liquid crystal elements to which various modes are applied can be used. For example, a liquid crystal element to which a VA (Vertical Alignment) mode, a TN (Twisted Nematic) mode, an IPS (In-Plane-Switching) mode, an ASM (Axially Symmetric Aligned Micro-cell) mode, an OCB (Opticaly Compensated Bend) mode, an FLC (Ferroelectric Liquid Crystal) mode, an AFLC (AntiFerroelectric Liquid Crystal) mode, an ECB (Electrically Controlled Birefringence) mode, a VA-IPS mode, a guest-host mode, or the like is applied can be used.

[0219] The liquid crystal display device described in this embodiment may be a normally black liquid crystal display device, for example, a transmissive liquid crystal display device employing a vertical alignment (VA) mode. As the vertical alignment mode, a multi-domain vertical alignment (MVA) mode, a patterned vertical alignment (PVA) mode, an advanced super view (ASV) mode, or the like may be used.

[0220] A liquid crystal element is a device that controls the transmission or non-transmission of light by the optical modulation action of liquid crystal. The optical modulation action of liquid crystal is controlled by an electric field (including a horizontal electric field, a vertical electric field, or an oblique electric field) applied to the liquid crystal. Liquid crystals that can be used in liquid crystal elements include thermotropic liquid crystals, low-molecular-weight liquid crystals, polymer liquid crystals, polymer-dispersed liquid crystals (PDLC: Polymer Dispersed Liquid Crystal), polymer network liquid crystals (PNLC: Polymer Network Liquid Crystal), ferroelectric liquid crystals, and antiferroelectric liquid crystals. These liquid crystal materials exhibit cholesteric phases, smectic phases, cubic phases, chiral nematic phases, isotropic phases, and the like, depending on the conditions.

[0221] The spacers 565 are columnar spacers obtained by selectively etching an insulating layer, and are provided to control the distance (cell gap) between the pixel electrode 541 and the counter electrode 542. Spherical spacers may also be used.

[0222] The counter electrode 542 is preferably formed using a material with high visible light transmittance. For example, it can be formed using indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide doped with gallium, or the like. Metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or titanium, alloys containing these metal materials, or nitrides of these metal materials (e.g., titanium nitride), can also be used by forming them thin enough to have light-transmitting properties. A stacked film of the above materials can also be used as the conductive layer. For example, a stacked film of an alloy of silver and magnesium and indium tin oxide is preferable because it can increase conductivity. Graphene, or the like, may also be used.

[0223] The liquid crystal display device has a light-shielding layer 544, a colored layer 543 (colored layers 543R, 543G, and 543B), and an insulating layer 548 between a substrate 562 (corresponding to the substrate 292 in FIG. 21 ) and a counter electrode 542. In addition, a polarizing plate 572 is provided on the surface of the substrate 562.

[0224] Materials that can be used for the light-shielding layer 544 include carbon black, titanium black, metals, metal oxides, and composite oxides containing a solid solution of multiple metal oxides. The light-shielding layer 544 may be a film containing a resin material or a thin film of an inorganic material such as a metal. The light-shielding layer 544 may also be a laminated film of films containing the material of the coloring layer 543. For example, a laminated structure may be used in which a film containing the material used for the coloring layer 543 that transmits light of one color and a film containing the material used for the coloring layer 543 that transmits light of another color. Using a common material for the coloring layer 543 and the light-shielding layer is preferred because it allows for the use of common equipment and simplifies the process.

[0225] Materials that can be used for the coloring layer 543 include metal materials, resin materials, and resin materials containing pigments or dyes. By appropriately selecting and using such materials, it is possible to generate light of R (red), G (green), B (blue), etc., thereby enabling full-color display. The coloring layer 543R shown in FIG. 22 can transmit red light, the coloring layer 543G can transmit green light, and the coloring layer 543B can transmit blue light.

[0226] Note that a color conversion layer containing a semiconductor material may be used instead of the coloring layer 543. For example, when light of a certain wavelength is incident on a layer having a nano-sized semiconductor, it can be converted into light of another wavelength.

[0227] When high-energy light is irradiated onto certain semiconductors, they enter an excited state, and light is emitted when they transition to a stable state. The wavelength of the light emitted by the semiconductor is determined by the energy gap of the semiconductor material, but in nano-sized semiconductors, electrons, holes, or excitons are trapped inside them, making the energy state discrete and causing an energy shift. As a result, the wavelength of the light emitted by the semiconductor also changes.

[0228] Such nano-sized semiconductors are called quantum dots. The amount of energy shift depends on the size of the quantum dots, so the emission wavelength can be easily adjusted by adjusting the size of the quantum dots. Furthermore, quantum dots have a narrow peak width in the emission spectrum because their discrete nature limits phase relaxation, allowing emission with good color purity to be obtained. Therefore, a color conversion layer containing quantum dots can be used as a substitute for the coloring layer 543.

[0229] [Display Panel 200D] The display panel 200D shown in FIG. 23 differs from the display panel 200A mainly in the configuration of the transistors.

[0230] The transistor 320 is a transistor (OS transistor) in which a metal oxide (also referred to as an oxide semiconductor) is used for a semiconductor layer in which a channel is formed.

[0231] The transistor 320 includes a semiconductor layer 321 , an insulating layer 323 , a conductive layer 324 , a pair of conductive layers 325 , an insulating layer 326 , and a conductive layer 327 .

[0232] 21 . An insulating layer 332 is provided over the substrate 331. The insulating layer 332 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the substrate 331 to the transistor 320 and prevents oxygen from being released from the semiconductor layer 321 toward the insulating layer 332. The insulating layer 332 can be, for example, a film through which hydrogen or oxygen is less likely to diffuse than a silicon oxide film, such as an aluminum oxide film, a hafnium oxide film, or a silicon nitride film.

[0233] A conductive layer 327 is provided over the insulating layer 332, and an insulating layer 326 is provided to cover the conductive layer 327. The conductive layer 327 functions as a first gate electrode of the transistor 320, and part of the insulating layer 326 functions as a first gate insulating layer. An oxide insulating film such as a silicon oxide film is preferably used for at least a portion of the insulating layer 326 that is in contact with the semiconductor layer 321. The top surface of the insulating layer 326 is preferably planarized.

[0234] The semiconductor layer 321 is provided over the insulating layer 326. The semiconductor layer 321 preferably includes a metal oxide (also referred to as an oxide semiconductor) film exhibiting semiconductor characteristics. A pair of conductive layers 325 is provided on and in contact with the semiconductor layer 321 and functions as a source electrode and a drain electrode.

[0235] An insulating layer 328 is provided to cover top surfaces and side surfaces of the pair of conductive layers 325 and side surfaces of the semiconductor layer 321, and an insulating layer 264 is provided over the insulating layer 328. The insulating layer 328 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the insulating layer 264 or the like into the semiconductor layer 321 and prevents oxygen from being released from the semiconductor layer 321. The insulating layer 328 can be an insulating film similar to the insulating layer 332.

[0236] An opening reaching the semiconductor layer 321 is provided in the insulating layer 328 and the insulating layer 264. An insulating layer 323 in contact with the top surface of the semiconductor layer 321 and a conductive layer 324 are buried in the opening. The conductive layer 324 functions as a second gate electrode, and the insulating layer 323 functions as a second gate insulating layer.

[0237] The upper surfaces of the conductive layer 324, the insulating layer 323, and the insulating layer 264 are planarized so that their heights are the same or approximately the same, and insulating layers 329 and 265 are provided to cover them.

[0238] The insulating layer 264 and the insulating layer 265 function as interlayer insulating layers. The insulating layer 329 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the insulating layer 265 or the like to the transistor 320. The insulating layer 329 can be formed using an insulating film similar to the insulating layer 328 and the insulating layer 332.

[0239] A plug 274 electrically connected to one of the pair of conductive layers 325 is provided so as to be embedded in the insulating layer 265, the insulating layer 329, and the insulating layer 264. Here, the plug 274 preferably has a conductive layer 274a covering the side surfaces of the openings of the insulating layer 265, the insulating layer 329, the insulating layer 264, and the insulating layer 328 and a part of the upper surface of the conductive layer 325, and a conductive layer 274b in contact with the upper surface of the conductive layer 274a. In this case, it is preferable to use a conductive material through which hydrogen and oxygen do not easily diffuse as the conductive layer 274a.

[0240] Note that the structure of the transistor included in the display panel of this embodiment is not particularly limited. For example, a planar transistor, a staggered transistor, an inverted staggered transistor, or the like can be used. Furthermore, either a top-gate transistor or a bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below a semiconductor layer in which a channel is formed.

[0241] The transistor 320 has a structure in which a semiconductor layer in which a channel is formed is sandwiched between two gates. The two gates may be connected and the transistor may be driven by supplying the same signal to them. Alternatively, the threshold voltage of the transistor may be controlled by applying a potential for controlling the threshold voltage to one of the two gates and a potential for driving to the other.

[0242] The crystallinity of a semiconductor material used for a semiconductor layer of a transistor is not particularly limited, and any of an amorphous semiconductor, a single-crystal semiconductor, and a semiconductor having crystallinity other than single crystal (a microcrystalline semiconductor, a polycrystalline semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a single-crystal semiconductor or a crystalline semiconductor is preferable because it can suppress deterioration of transistor characteristics.

[0243] The band gap of the metal oxide used for the semiconductor layer of the transistor is preferably 2 eV or more, more preferably 2.5 eV or more. Use of a metal oxide with a wide band gap can reduce the off-state current of the OS transistor.

[0244] The metal oxide preferably contains at least indium or zinc, and more preferably contains indium and zinc. For example, the metal oxide preferably contains indium, M (M is one or more selected from gallium, aluminum, yttrium, tin, silicon, boron, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, and cobalt), and zinc.

[0245] Alternatively, the semiconductor layer of the transistor may contain silicon, such as amorphous silicon or crystalline silicon (such as low-temperature polysilicon or single-crystal silicon).

[0246] Examples of metal oxides that can be used in the semiconductor layer include indium oxide, gallium oxide, and zinc oxide. The metal oxide preferably contains two or three elements selected from indium, element M, and zinc. The element M is one or more elements selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium. In particular, the element M is preferably one or more elements selected from aluminum, gallium, yttrium, and tin.

[0247] When a metal oxide is used for the semiconductor layer, the metal oxide is preferably formed by a sputtering method or an ALD method. When the metal oxide is formed by a sputtering method, productivity and film density can be increased. When the metal oxide is formed by an ALD method, film coverage can be increased.

[0248] In particular, as the metal oxide used for the semiconductor layer, it is preferable to use an oxide containing indium, gallium, and zinc (also referred to as IGZO). Alternatively, it is preferable to use an oxide containing indium, tin, and zinc (also referred to as ITZO (registered trademark)). Alternatively, it is preferable to use an oxide containing indium, gallium, tin, and zinc. Alternatively, it is preferable to use an oxide containing indium, aluminum, and zinc (also referred to as IAZO). Alternatively, it is preferable to use an oxide containing indium, aluminum, gallium, and zinc (also referred to as IAGZO). Alternatively, it is preferable to use an oxide containing indium and zinc. Alternatively, it is preferable to use an oxide containing indium and gallium.

[0249] When the metal oxide used in the semiconductor layer is an In-M-Zn oxide, the atomic ratio of In in the In-M-Zn oxide is preferably equal to or greater than the atomic ratio of M. Examples of atomic ratios of metal elements in such an In-M-Zn oxide include a composition of In:M:Zn=1:1:1 or thereabouts, In:M:Zn=1:1:1 or thereabouts, In:M:Zn=1:1:1.2 or thereabouts, In:M:Zn=1:3:2 or thereabouts, In:M:Zn=1:3:4 or thereabouts, In:M:Zn=2:1:3 or thereabouts, In:M:Zn=3:1:2 or thereabouts, In:M:Zn=4:2: Examples of such compositions include a composition of In:M:Zn=4:2:4.1 or a composition of In:M:Zn=5:1:3 or a composition of In:M:Zn=5:1:6 or a composition of In:M:Zn=5:1:7 or a composition of In:M:Zn=5:1:8 or a composition of In:M:Zn=6:1:6 or a composition of In:M:Zn=5:2:5 or a composition of In:M:Zn=5:2:5. Note that a composition of a similar ratio includes a range of ±30% of the desired atomic ratio.

[0250] Furthermore, it is preferable to use gallium or tin as the element M. Note that the element M may be a combination of two or more of the above elements. It is also preferable to use In:M:Zn=40:1:10 or a metal oxide thereof in the semiconductor layer. Specifically, it is preferable to use In:Sn:Zn=40:1:10 or a metal oxide thereof in the semiconductor layer.

[0251] For example, when describing a composition having an atomic ratio of In:Ga:Zn=4:2:3 or thereabout, this includes a case where, when In is taken as 4, Ga is 1 to 3 and Zn is 2 to 4. Furthermore, when describing a composition having an atomic ratio of In:Ga:Zn=5:1:6 or thereabout, this includes a case where, when In is taken as 5, Ga is more than 0.1 and 2 or less and Zn is 5 to 7. Furthermore, when describing a composition having an atomic ratio of In:Ga:Zn=1:1:1 or thereabout, this includes a case where, when In is taken as 1, Ga is more than 0.1 and 2 or less and Zn is more than 0.1 and 2 or less.

[0252] The semiconductor layer may also have two or more metal oxide layers with different compositions. For example, a stacked structure of a first metal oxide layer having an In:M:Zn=1:3:4 (atomic ratio) or a composition similar thereto and a second metal oxide layer having an In:M:Zn=1:1:1 (atomic ratio) or a composition similar thereto provided on the first metal oxide layer is preferably used. Gallium or aluminum is particularly preferably used as the element M.

[0253] Alternatively, for example, a stacked structure of any one selected from indium oxide, indium gallium oxide, and IGZO and any one selected from IAZO, IAGZO, and ITZO (registered trademark) may be used.

[0254] As the crystalline oxide semiconductor, for example, an oxide semiconductor having a CAAC (c-axis aligned crystal) structure, a polycrystalline (poly-crystal) structure, a nanocrystalline (nc: nano-crystal) structure, or the like can be used. A crystalline oxide semiconductor has a low defect state density, and a highly reliable transistor can be realized. Note that the CAAC structure is a crystal structure in which a plurality of microcrystals (typically, a plurality of IGZO microcrystals) have a c-axis orientation and are connected without being oriented in the a-b plane. The CAAC structure allows the crystal grain boundaries (grains) to be less clearly visible in the a-b plane than the polycrystalline structure, and therefore a highly reliable transistor can be realized.

[0255] An OS transistor has significantly higher field-effect mobility than a transistor using amorphous silicon. Furthermore, an OS transistor has significantly lower source-drain leakage current (also referred to as off-state current) in an off state, and can hold charge accumulated in a capacitor connected in series with the transistor for a long period of time. Furthermore, the use of an OS transistor can reduce the power consumption of a display panel.

[0256] [Display Panel 200F] A display panel 200F shown in FIG. 24 has a stacked structure of a transistor 310 in which a channel is formed in a substrate 301 and a transistor 320 in which a channel is formed and a semiconductor layer containing metal oxide is formed.

[0257] An insulating layer 261 is provided to cover the transistor 310, and a conductive layer 251 is provided over the insulating layer 261. An insulating layer 262 is provided to cover the conductive layer 251, and a conductive layer 252 is provided over the insulating layer 262. The conductive layers 251 and 252 each function as wirings. An insulating layer 263 and an insulating layer 332 are provided to cover the conductive layer 252, and the transistor 320 is provided over the insulating layer 332. An insulating layer 265 is provided to cover the transistor 320, and a capacitor 240 is provided over the insulating layer 265. The capacitor 240 and the transistor 320 are electrically connected by a plug 274.

[0258] The transistor 320 can be used as a transistor that forms a pixel circuit. The transistor 310 can be used as a transistor that forms a pixel circuit or a driver circuit (gate line driver circuit, source line driver circuit) that drives the pixel circuit. The transistors 310 and 320 can be used as transistors that form various circuits such as an arithmetic circuit or a memory circuit.

[0259] With this configuration, not only pixel circuits but also driving circuits etc. can be formed directly below the light-emitting device, which makes it possible to make the display panel smaller than when driving circuits are provided around the periphery of the display area.

[0260] [Display Panel 200G] The display panel 200G shown in Fig. 25 has a configuration in which the transistor 320 of the display panel 200F shown in Fig. 24 is replaced with a transistor 320A (vertical transistor). Note that the configuration in which the transistor 320 is replaced with the transistor 320A can also be applied to the display panel 200D shown in Fig. 23.

[0261] 26A shows a cross-sectional view of the transistor 320A in the XZ plane, and FIG. 26B shows a cross-sectional view of the transistor 320A in the XY plane including the wiring 440.

[0262] The transistor 320A includes an oxide semiconductor 470, an insulator 430, and a conductor 420. The oxide semiconductor 470 functions as a semiconductor layer, the insulator 430 functions as a gate insulator, and the conductor 420 functions as a gate electrode. The wiring 450 has a region that functions as one of a source electrode and a drain electrode of the transistor 320A. The wiring 440 has a region that functions as the other of the source electrode and the drain electrode of the transistor 320A.

[0263] An opening 490 is provided through the wiring 440 and the insulator 480, reaching the wiring 450. The opening 490 has a columnar shape with a substantially circular upper surface. This structure allows for miniaturization or high integration of memory cells. Note that the side surface of the opening 490 is preferably perpendicular to the upper surface of the wiring 450.

[0264] At least a part of the oxide semiconductor 470 is disposed in the opening 490. Note that the oxide semiconductor 470 has a region in contact with the top surface of the wiring 450, a region in contact with the side surface of the wiring 440, and a region in contact with the side surface of the insulator 480 in the opening 490.

[0265] The insulator 430 is disposed so that at least a portion thereof covers the opening 490. The conductor 420 is disposed so that at least a portion thereof is located in the opening 490. Note that the conductor 420 is preferably provided so as to fill the opening 490, and the top surface thereof is preferably approximately circular in order to increase the degree of integration.

[0266] As illustrated in FIG. 26A, the oxide semiconductor 470 includes a region 470i and regions 470na and 470nb that sandwich the region 470i.

[0267] The region 470na is a region of the oxide semiconductor 470 that is in contact with the wiring 450. At least a part of the region 470na functions as one of the source region and the drain region of the transistor 320A. The region 470nb is a region of the oxide semiconductor 470 that is in contact with the wiring 440. At least a part of the region 470nb functions as the other of the source region and the drain region of the transistor 320A. As shown in FIG. 26B , the wiring 440 is in contact with the entire periphery of the oxide semiconductor 470. Therefore, the other of the source region and the drain region of the transistor 320A can be formed along the entire periphery of a portion of the oxide semiconductor 470 that is formed in the same layer as the wiring 440.

[0268] The region 470i is a region sandwiched between the regions 470na and 470nb in the oxide semiconductor 470. At least part of the region 470i functions as a channel formation region of the transistor 320A. That is, the channel formation region of the transistor 320A is formed in a part of the oxide semiconductor 470 located between the wiring 450 and the wiring 440. It can also be said that the channel formation region of the transistor 320A is located in a region of the oxide semiconductor 470 that is in contact with the insulator 480 or in a region in the vicinity of the insulator 480.

[0269] The channel length of the transistor 320A is the distance between the source region and the drain region. In other words, the channel length of the transistor 320A can be determined by the thickness of the insulator 480 on the wiring 450. In FIG. 26A , the channel length L of the transistor 320A is indicated by a dashed double-headed arrow. The channel length L is the distance between the end of the region where the oxide semiconductor 470 and the wiring 450 contact each other and the end of the region where the oxide semiconductor 470 and the wiring 440 contact each other in a cross-sectional view. In other words, the channel length L corresponds to the length of the side surface of the insulator 480 on the opening 490 side in a cross-sectional view.

[0270] In conventional transistors, the channel length is set by the exposure limit of photolithography. However, in one embodiment of the present invention, the channel length can be set by the film thickness of the insulator 480. Therefore, the channel length of the transistor 320A can be made into an extremely fine structure that is equal to or less than the exposure limit of photolithography (for example, 60 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, 20 nm or less, or 10 nm or less, and 1 nm or more, or 5 nm or more). This allows the on-state current of the transistor 320A to be increased.

[0271] Furthermore, as described above, the channel formation region, the source region, and the drain region can be formed in the opening 490. This allows the area occupied by the transistor 320A to be reduced compared to a conventional transistor in which the channel formation region, the source region, and the drain region are provided separately on the XY plane, thereby increasing the pixel density.

[0272] A transistor having a channel formation region along the side surface of the insulator 480 in the opening 490 is also called a vertical transistor.

[0273] 26B , the oxide semiconductor 470, the insulator 430, and the conductor 420 are also arranged concentrically in the XY plane including the channel formation region of the oxide semiconductor 470. Therefore, the side surface of the conductor 420 located at the center faces the side surface of the oxide semiconductor 470 with the insulator 430 interposed therebetween. That is, the entire periphery of the oxide semiconductor 470 forms the channel formation region in a top view. In this case, for example, the channel width of the transistor 320A is determined by the perimeter of the oxide semiconductor 470. That is, the channel width of the transistor 320A can be determined by the maximum width of the opening 490 (the maximum diameter when the opening 490 is circular in a top view). In FIGS. 26A and 26B , the maximum width D of the opening 490 is indicated by a double-headed, dashed arrow. In FIG. 26B , the channel width W of the transistor 320A is indicated by a double-headed, dashed arrow. By increasing the maximum width D of the opening 490, the channel width per unit area can be increased, and the on-current can be increased.

[0274] When the opening 490 is formed by photolithography, the maximum width D of the opening 490 is set by the exposure limit of photolithography. The maximum width D of the opening 490 is set by the film thicknesses of the oxide semiconductor 470, the insulator 430, and the conductor 420 provided in the opening 490. The maximum width D of the opening 490 is, for example, 5 nm or more, 10 nm or more, or 20 nm or more, and preferably 100 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, or 30 nm or less. When the opening 490 has a circular shape in top view, the maximum width D of the opening 490 corresponds to the diameter of the opening 490, and the channel width W can be calculated as "D × π."

[0275] In the memory device of one embodiment of the present invention, the channel length L of the transistor 320A is preferably at least shorter than the channel width W of the transistor 320A. The channel length L of the transistor 320A of one embodiment of the present invention is 0.1 to 0.99 times, preferably 0.5 to 0.8 times, the channel width W of the transistor 320A. With such a structure, a transistor with favorable electrical characteristics and high reliability can be realized.

[0276] Furthermore, by forming the opening 490 to have a substantially circular shape in top view, the oxide semiconductor 470, the insulator 430, and the conductor 420 are arranged concentrically. This makes the distance between the conductor 420 and the oxide semiconductor 470 substantially uniform, allowing a gate electric field to be applied to the oxide semiconductor 470 substantially uniformly.

[0277] The channel formation region of a transistor using an oxide semiconductor for a semiconductor layer preferably has fewer oxygen vacancies or a lower concentration of impurities such as hydrogen, nitrogen, or metal elements than the source and drain regions. For example, the aluminum concentration in the channel formation region of the oxide semiconductor is preferably 1×10 ２２ atoms / cm ３ Preferably, 1×10 ２１ atoms / cm ３ More preferably, 1×10 ２０ atoms / cm ３Less than 5 x 10 is more preferable. １９ atoms / cm ３ More preferably, 1×10 １９ atoms / cm ３ Less than 5 x 10 is more preferable. １８ atoms / cm ３ More preferably, 1×10 １８ atoms / cm ３ The following is even more preferred:

[0278] In addition, hydrogen atoms near the oxygen vacancies are converted into defects where hydrogen atoms have entered the oxygen vacancies (hereinafter referred to as V Ｏ H) and generate electrons that become carriers. Therefore, in the channel formation region, V Ｏ It is preferable that H is also reduced. In this way, the channel formation region of the transistor is a high-resistance region with a low carrier concentration. Therefore, the channel formation region of the transistor can be said to be i-type (intrinsic) or substantially i-type.

[0279] In addition, the source and drain regions of a transistor using an oxide semiconductor for a semiconductor layer have more oxygen vacancies than the channel formation region. Ｏ The source and drain regions of a transistor are n-type regions with a high carrier concentration and low resistance compared to the channel formation region, due to a high concentration of H or a high concentration of impurities such as hydrogen, nitrogen, and metal elements.

[0280] 26A and other drawings, the opening 490 is provided so that the side surface of the opening 490 is perpendicular to the upper surface of the wiring 450, but the present invention is not limited to this. For example, the side surface of the opening 490 may be tapered.

[0281] Fig. 27A shows a cross-sectional view in the XZ plane of a transistor 320B, which is a vertical transistor having a different configuration from that shown in Fig. 26. Fig. 27B shows a cross-sectional view in the XY plane.

[0282] The transistor 320B differs from the transistor 320A mainly in that it does not include the wiring 450, is provided over the insulator 460, includes wirings 440S and 440D instead of the wiring 440, and has a different shape of the oxide semiconductor 470. The wiring 440S functions as a source electrode, and the wiring 440D functions as a drain electrode.

[0283] The oxide semiconductor 470 has a ring shape. Specifically, the opening 490 has a region in contact with the side surface of the wiring 440S, a region in contact with the side surface of the wiring 440D, and a region in contact with the side surface of the insulator 480. Here, the oxide semiconductor 470 is not in contact with the top surfaces of the wiring 440S and the wiring 440D. The oxide semiconductor 470 having such a shape can be formed by processing, for example, anisotropic etching.

[0284] 27B , the width H of the wiring 440S and the wiring 440D is smaller than the maximum width D of the opening 490. In this case, the circumferential direction of the opening 490 corresponds to the channel length direction of the transistor 320B. Here, because the oxide semiconductor 470 has a ring shape, there are two types of current paths (i.e., channels) from the wiring 440S to the wiring 440D. Note that the oxide semiconductor 470 does not necessarily have to have a ring shape and may be in contact with both the wiring 440S and the wiring 440D.

[0285] The channel length can be controlled by the shape and size of the opening 490. For example, if the channel length is desired to be increased, the perimeter of the opening 490 can be increased. Although an example in which the opening 490 is circular in plan view has been shown, the present invention is not limited to this. For example, the opening 490 can be circular, elliptical, rectangular, or other shapes in plan view. It can also be a regular polygon, such as an equilateral triangle, square, or regular pentagon, or a polygon other than a regular polygon. Furthermore, a concave polygon, such as a star-shaped polygon, in which at least one interior angle exceeds 180 degrees, can increase the channel width. Other shapes include an ellipse, a polygon with rounded corners, and a closed curve combining straight lines and curves. In this case, the maximum width of the opening 490 can be calculated appropriately based on the shape of the top of the opening 490. For example, if the opening is square or rectangular in plan view, the maximum width of the opening 490 can be the length of the diagonal line at the top of the opening 490.

[0286] 27A , the height of the oxide semiconductor 470 corresponds to the channel width W of the transistor 320B. Therefore, the channel width W of the transistor 320B can be controlled by the thickness of the insulator 480. Therefore, the channel width of the transistor 320B can be made into an extremely fine structure that is equal to or smaller than the exposure limit of photolithography (for example, 60 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, 20 nm or less, or 10 nm or less, and 1 nm or more, or 5 nm or more).

[0287] The transistor 320A has an extremely small channel length and a large channel width, and can achieve a high on-state current. On the other hand, the transistor 320B has an extremely small channel width and a large channel length, and can achieve an appropriate on-state current, which makes design easy. The transistors 320A and 320B can be fabricated in part over the same substrate.

[0288] 28A and 28B are diagrams showing an example of a semi-transmissive liquid crystal display device. In a semi-transmissive liquid crystal display device, light that passes through a substrate is used as display light, so a substrate that is opaque to visible light, such as a silicon substrate, cannot be used. Therefore, the circuit portion can have a configuration similar to that of the display panel 200D shown in FIG. 16.

[0289] [Display Panel 200H] The display panel 200H shown in FIG. 28A has a configuration in which a half-mirror type semi-transmissive / semi-reflective layer is used for the pixel electrode 541h, and corresponds to the transflective liquid crystal display device 20t shown in FIG. 11A. The pixel electrode 541h can be a thin metal layer that can transmit light. Alternatively, it may be a laminate of a thin metal layer and a translucent conductive film. In addition, a polarizing plate 573 is provided on the surface of the substrate 331.

[0290] The metal layer can be made of, for example, a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or titanium, an alloy containing these metal materials, or a nitride of these metal materials (for example, titanium nitride), etc. The light-transmitting conductive film can be made of a material having high transmittance for visible light that can be used for the counter electrode 542 described above.

[0291] A colored layer (here, colored layer 543B is exemplified) is provided on the liquid crystal element 547. White light (W) passing through the pixel electrode 541h can be emitted to the outside, with all components other than blue light absorbed by the colored layer 543B. Furthermore, white light incident from the colored layer 543B side can be emitted to the outside, with all components other than blue light absorbed by the colored layer 543B, reflected by the pixel electrode 541h, and emitted to the outside. Therefore, the device can operate as both a transmissive liquid crystal display device and a reflective liquid crystal display device.

[0292] [Display Panel 200J] The display panel 200J shown in Figure 28B has a pixel electrode 541h including a light-reflective conductive layer 541r and a light-transmitting conductive layer 541t, and corresponds to the semi-transmissive liquid crystal display device 20t shown in Figure 11B. A portion of the conductive layer 541t is provided on the conductive layer 541r, thereby electrically connecting the two. The region provided with the conductive layer 541r can operate as a reflective liquid crystal display device, while the region provided with the conductive layer 541t can operate as a transmissive liquid crystal display device.

[0293] The conductive layer 541r can be made of a material with high visible light transmittance that can be used for the counter electrode 542. The conductive layer 541t can be made of a material with high visible light reflectance that can be used for the pixel electrode 541.

[0294] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes and examples described in this specification.

[0295] 10: eye, 20t: semi-transmissive liquid crystal display device, 20: reflective liquid crystal display device, 21: liquid crystal layer, 22: linear polarizer, 23h: semi-transmissive / semi-reflective layer, 23t: light-transmitting layer, 23r: reflective layer, 23: reflective layer, 24B: light-emitting source, 24G: light-emitting source, 24L: light-emitting source, 24P: light guide plate, 24R: light-emitting source, 24T: trigger, 24: surface light source, 25: retardation plate, 26: linear polarizer, 27M: reflective layer, 27: surface light source, 28: linear polarizer, 30: reflective polarizer, 31: lens, 32: lens, 33: lens, 34: lens, 41: retardation plate, 42: half mirror, 70: pixel, 71: sub-pixel , 74: pixel array, 75: circuit, 76: circuit, 77: layer, 78: layer, 79: layer, 80: layer, 90: housing, 91: band, 92: display unit, 93: light-receiving window, 94: optical sensor, 95: display unit, 96: light-transmitting portion, 200A: display panel, 200D: display panel, 200F: display panel, 200G: display panel, 200H: display panel, 200J: display panel, 240: capacitor, 241: conductive layer, 243: insulating layer, 245: conductive layer, 251: conductive layer, 252: conductive layer, 254: insulating layer, 255: insulating layer, 256: plug, 261: insulating layer, 262: insulating layer, 263: insulating layer, 264: insulating layer, 265: insulating layer, 271: plug, 274a: conductive layer, 274b: conductive layer, 274: plug, 280: display module, 281: display unit, 290: FPC, 291: substrate, 292: substrate, 301: substrate, 310: transistor, 311: conductive layer, 312: low resistance region, 313: insulating layer, 314: insulating layer, 315: element isolation layer, 320A: transistor, 320B: transistor, 320: transistor, 321: semiconductor layer, 323: insulating layer, 324: conductive layer, 325: conductive layer, 326: insulating layer, 327: conductive layer, 328: Insulating layer, 329: insulating layer, 331: substrate, 332: insulating layer, 420: conductor, 430: insulator, 440D: wiring, 440S: wiring, 440: wiring, 450: wiring, 460: insulator, 470i: region, 470na: region, 470nb: region, 470: oxide semiconductor, 480: insulator, 490: opening, 541h: pixel electrode, 541r: conductive layer, 541t: conductive layer, 541: pixel electrode, 542: counter electrode, 543B: colored layer, 543G: colored layer, 543R: colored layer, 543: colored layer, 544: light-shielding layer, 545a: alignment film, 545b: alignment film, 547: liquid crystal element,548: insulating layer, 562: substrate, 565: spacer, 572: polarizing plate, 573: polarizing plate,

Claims

A reflective liquid crystal display device, a surface light source, a reflective polarizing plate, a retardation plate, and a half mirror, a display surface of the reflective liquid crystal display device facing a light emitting surface of the surface light source; the reflective polarizing plate is provided at an angle such that light emitted from the display surface and traveling straight through the surface light source is obliquely incident thereon, the retardation plate and the half mirror are provided in this order from the reflective polarizing plate side in a direction in which the light reflected by the reflective polarizing plate travels. 　 In claim 1, The half mirror is an electronic device having a curved surface with a concave surface facing the reflective polarizing plate. 　 In claim 1, The reflective liquid crystal display device is an electronic device having, from the surface light source side, a linear polarizer, a liquid crystal layer, and a reflective layer in this order. 　 In claim 3, An electronic device having a retardation plate between the linear polarizer and the liquid crystal layer. 　 In claim 1, The surface light source includes a light source and a light guide plate. The light emission source includes first to third light emission sources, the first light emitting source has a function of emitting red light, the second light source has a function of emitting green light, the third light source has a function of emitting blue light, The electronic device has a function of independently adjusting the illuminance of each of the first to third light sources. 　 In any one of claims 1 to 5, The electronic device further includes a lens disposed between the surface light source and the reflective polarizing plate. 　 A semi-transmissive liquid crystal display device, a surface light source, a reflective polarizing plate, a retardation plate, and a half mirror, a surface opposite to a display surface of the semi-transmissive liquid crystal display device faces a light emitting surface of the surface light source; the reflective polarizing plate is provided at an angle such that the light emitted from the display surface and traveling straight is obliquely incident thereon, the retardation plate and the half mirror are provided in this order from the reflective polarizing plate side in a direction in which the light reflected by the reflective polarizing plate travels. 　 In claim 7, The half mirror is an electronic device having a curved surface with a concave surface facing the reflective polarizing plate. 　 In claim 7, The semi-transmissive liquid crystal display device is an electronic device having, from the reflective polarizer side, a first linear polarizer, a liquid crystal layer, a semi-transmissive / semi-reflective layer, and a second linear polarizer, in this order. 　 In claim 9, The semi-transmitting and semi-reflective layer is a half-mirror type electronic device. 　 In claim 9, The semi-transmitting and semi-reflective layer of the electronic device includes a reflective layer and a light-transmitting layer. 　 In claim 7, The surface light source includes a light emitting source and a light guide plate, The surface light source has a reflective layer on a surface opposite to the light emitting surface, The light emission source includes first to third light emission sources, the first light emitting source has a function of emitting red light, the second light source has a function of emitting green light, the third light source has a function of emitting blue light, The electronic device wherein the first to third light emission sources each have a function of adjusting the light emission intensity. 　 In claim 7, The surface light source has a function of transmitting light, The surface light source includes a light emitting source and a light guide plate, The light emission source includes first to third light emission sources, the first light emitting source has a function of emitting red light, the second light source has a function of emitting green light, the third light source has a function of emitting blue light, The electronic device wherein the first to third light emission sources each have a function of adjusting the light emission intensity. 　 In claim 13, The device has a housing, the semi-transmissive liquid crystal display device, the surface light source, the reflective polarizing plate, the retardation plate, and the half mirror are housed in the housing; The electronic device has a light-collecting window in an area of ​​the housing that overlaps with the surface light source. 　 In any one of claims 7 to 14, An electronic device in which a lens is provided between the semi-transmissive liquid crystal display device and the reflective polarizer. 　 A method for operating an electronic device having a reflective liquid crystal display device or a semi-transmissive liquid crystal display device to which light is incident from a first light source and a second light source, comprising the steps of: acquiring illuminance and chromaticity of light emitted from the first light source by a light sensor; Varying the illuminance of the second light source so as to have a negative slope with respect to the illuminance; A method for operating an electronic device, which changes the chromaticity of light emitted by a second light source depending on the chromaticity so that the light incident on the reflective liquid crystal display device or the semi-transmissive liquid crystal display device is white or a color close to the white color.

Images