Electronic apparatus

Abstract

The purpose of the present invention is to provide an electronic apparatus capable of easily obtaining accurate line-of-sight information.　The electronic apparatus according to the present invention has a display device (20), a catadioptric optical system (30), and a light source (80) that emits infrared light, the display device (20) having light-emitting elements and light-receiving elements in pixels (21). The catadioptric optical system (30) forms two different optical paths between the outer surface (42) of the eye (40) and light-receiving elements, and between the light-emitting elements and the retina (41). Visible light (VL) is used between the light-emitting elements and the retina (41) and infrared light (IR) is used between the outer surface (42) of the eye (40) and the light-receiving elements. Additionally, half mirrors (33, 34) through which the light of one wavelength not involved in the optical path passes are used in the respective optical paths. Consequently, the focal distance of each optical path can be adjusted.

Description

electronic equipment

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

[0002] It should be noted that one aspect of the present invention is not limited to the above-mentioned technical field. The technical field of one aspect of the invention disclosed herein relates to a product, a method, or a method of manufacture. Alternatively, one aspect of the present invention relates to a process, a machine, a manufacture, or a composition of matter. More specifically, examples of the technical fields of one aspect of the present invention disclosed herein include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, energy storage devices, memory devices, imaging devices, methods of operating them, or methods of manufacturing them.

[0003] In this specification, the term "semiconductor device" refers to any device that can function by utilizing semiconductor properties. Transistors and semiconductor circuits are examples of semiconductor devices. Furthermore, memory devices, display devices, imaging devices, and electronic devices may contain semiconductor devices.

[0004] Goggle-type devices and glasses-type devices are being developed as electronic devices for XR (a general term for virtual reality (VR), augmented reality (AR), mixed reality (MR), etc.).

[0005] Furthermore, typical examples of display panels used in these electronic devices include display devices equipped with liquid crystal elements, organic EL (Electroluminescence) elements, or light-emitting diodes (LEDs).

[0006] Display devices equipped with organic EL elements do not require a backlight, which is necessary for liquid crystal displays, thus enabling the realization of thin, lightweight, high-contrast, and low-power display devices. For example, an example of a display device using organic EL elements is described in Patent Document 1.

[0007] In addition, in a goggle-type device, an infrared light sensor may be implemented for the purpose of obtaining dynamic information of the eye or its vicinity, which is necessary for gaze detection and the like. For example, Patent Document 2 discloses an electronic device provided with a sensor function for detecting fatigue or abnormality from the blinking operation.

[0008] Japanese Patent Application Laid-Open No. 2002-324673 International Publication No. 2022 / 234383

[0009] Takashi Koiwa, "High Mobility Transparent Conductive Film", National Institute of Advanced Industrial Science and Technology, AIST Solar Power Generation Research Results Report 2019, Internet <URL: https: / / unit.aist.go.jp / rpd-envene / PV / ja / results / 2019 / oral / T13.pdf>

[0010] A sensor using infrared light with low visual sensitivity is effective for detecting information of the eye or its vicinity because it does not affect the visual recognition of an image. However, an increase in the number of parts is contrary to the miniaturization, light weight, and cost reduction of electronic devices. Therefore, in incorporating the light source and the sensor into an electronic device, contrivances for solving these problems are desired.

[0011] In addition, in order to improve the detection accuracy of the gaze, it is preferable to accurately detect the movement of the eyeball.To accurately detect the exact position of the eye (pupil), it can be said that it is appropriate to acquire a frontal image of the eye.However, in a goggle-type device, since an optical system and a display panel are arranged in front of the eye, the light source and the sensor for acquiring an image of the eye are arranged in an oblique direction where the optical system does not interfere with the eye.Therefore, there are cases where gaze information cannot be accurately obtained.

[0012] Therefore, one aspect of the present invention aims to provide an electronic device that can easily obtain accurate gaze information. Alternatively, it aims to provide an electronic device with low manufacturing costs. Alternatively, it aims to provide an electronic device equipped with a light source, a sensor, and an optical element. Alternatively, it aims to provide an electronic device that can detect movement information of the user's eyes or their vicinity. Alternatively, it aims to provide a novel electronic device. Alternatively, it aims to provide a novel semiconductor device, etc.

[0013] Furthermore, the description of these problems does not preclude the existence of other problems. Moreover, one aspect of the present invention does not need to solve all of these problems. Other problems will naturally become apparent from the description in the specification, drawings, and claims, and it is possible to extract other problems from the description in the specification, drawings, and claims.

[0014] One aspect of the present invention relates to an electronic device that has low manufacturing costs and facilitates the acquisition of accurate gaze information.

[0015] One aspect of the present invention is an electronic device worn in front of the eye, comprising a display device, a reflective / refracting optical system, and a light source, wherein the reflective / refracting optical system is positioned opposite the display surface of the display device, the display device has pixels having light-emitting elements and light-receiving elements, the reflective / refracting optical system comprises a first half-mirror and a second half-mirror, the first half-mirror having the function of transmitting visible light and semi-transmitting / semi-reflecting infrared light, the second half-mirror having the function of transmitting infrared light and semi-transmitting / semi-reflecting visible light, and the reflective / refracting optical system having the function of imaging visible light emitted by a light-emitting element onto the retina of the eye, and imaging infrared light emitted by a light source and reflected from the surface of the eye onto a light-receiving element.

[0016] A reflective-refractive optical system may have a configuration in which a linear polarizer, a first phase difference plate, one of a first half mirror and a second half mirror, the other of the first half mirror and the second half mirror, a second phase difference plate, and a reflective polarizer are arranged in that order in one direction from the display device side.

[0017] Preferably, a support is provided between the first half-mirror and the second half-mirror to support the first half-mirror and the second half-mirror, respectively.

[0018] The first half-mirror and the second half-mirror each have a concave surface, and it is preferable that the curvature of the first half-mirror is greater than the curvature of the second half-mirror.

[0019] Another aspect of the present invention is an electronic device worn in front of the eye, comprising a display device, a reflective / refracting optical system, and a light source, wherein the reflective / refracting optical system is positioned opposite the display surface of the display device, the display device has pixels having light-emitting elements and light-receiving elements, the reflective / refracting optical system comprises a first reflective polarizer and a second reflective polarizer, the first reflective polarizer having the function of transmitting infrared light, transmitting a first linearly polarized light in visible light, and reflecting a second linearly polarized light orthogonal to the first linearly polarized light, the second reflective polarizer having the function of transmitting visible light, transmitting a third linearly polarized light in infrared light, and reflecting a fourth linearly polarized light orthogonal to the third linearly polarized light, and the reflective / refracting optical system having the function of imaging visible light emitted by a light-emitting element onto the retina of the eye, and imaging infrared light emitted by a light source and reflected from the surface of the eye onto a light-receiving element.

[0020] A reflective and refractive optical system may have a configuration in which a linear polarizer, a first phase difference plate, a half mirror, a second phase difference plate, one of the first and second reflective polarizers, and the other of the first and second reflective polarizers are arranged in that order in one direction from the display device side.

[0021] Each pixel has a transistor connected to both the light-emitting element and the light-receiving element, and it is preferable that the transistor has a metal oxide in its channel-forming region. Furthermore, it is preferable that the metal oxide is indium oxide.

[0022] According to one aspect of the present invention, it is possible to provide an electronic device that makes it easy to obtain accurate gaze information. Alternatively, it is possible to provide an electronic device with low manufacturing costs. Alternatively, it is possible to provide an electronic device equipped with a light source, a sensor, and an optical element. Alternatively, it is possible to provide an electronic device that can detect movement information of the user's eyes or their vicinity. Alternatively, it is possible to provide a novel electronic device. Alternatively, it is possible to provide a novel semiconductor device, etc.

[0023] Furthermore, the description of these effects does not preclude the existence of other effects. One aspect of the present invention does not necessarily have to possess all of these effects. Other effects can be extracted from the description, drawings, and claims.

[0024] Figure 1 is a diagram illustrating electronic equipment. Figures 2A and 2B are diagrams illustrating reflective and refractive optical systems. Figures 3A, 3B, and 3C are diagrams illustrating the simulation results of a half-mirror. Figures 4A, 4B, 4C, 4D, 4E, 4F, 4G, 4H, and 4I are diagrams illustrating a support and a half-mirror. Figures 5A, 5B, 5C, 5D, 5E, 5F, 5G, 5H, and 5I are diagrams illustrating a support and a half-mirror. Figures 6A, 6B, 6C, and 6D are diagrams illustrating a light source. Figures 7A and 7B are diagrams illustrating reflective and refractive optical systems. Figures 8A and 8B are diagrams illustrating reflective and refractive optical systems. Figure 9 is a diagram illustrating electronic equipment. Figures 10A, 10B, and 10C are diagrams illustrating reflective and refractive optical systems. Figures 11A, 11B, 11C, 11D, and 11E illustrate a display device. Figures 12A, 12B, 12C, and 12D illustrate a display device. Figures 13A, 13B, 13C, 13D, 13E, 13F, and 13G illustrate a display device and a reflective / refractive optical system. Figures 14A, 14B, and 14C illustrate a pixel circuit. Figures 15A and 15B are perspective views illustrating electronic equipment. Figure 16 illustrates an example configuration of a display device. Figure 17 illustrates an example configuration of a display device. Figure 18 illustrates an example configuration of a display device. Figure 19 illustrates an example configuration of a display device. Figure 20 illustrates an example configuration of a display device. Figure 21 illustrates an example configuration of a display device. Figures 22A and 22B illustrate a transistor. Figures 23A and 23B illustrate the carrier concentration dependence of Hall mobility. Figure 23C is a cross-sectional view illustrating an indium oxide film.

[0025] Embodiments will be described in detail with reference to the drawings. However, it will be readily apparent to those skilled in the art that the present invention is not limited to the following description, and that its form and details can be modified in various ways without departing from the spirit and scope of the invention. Therefore, the present invention is not to be interpreted as being limited to the descriptions of the embodiments shown below. In the configuration of the invention described below, the same reference numerals are used in common between different drawings for the same parts or parts having similar functions, and repeated descriptions may be omitted. In addition, hatching of the same elements constituting the figures may be omitted or changed as appropriate between different drawings.

[0026] Furthermore, even if an element is shown as a single component in a circuit diagram, it can be composed of multiple components if there are no functional disadvantages. For example, multiple transistors that act as switches can sometimes be connected in series or parallel. Similarly, capacitors can be divided and placed in multiple locations.

[0027] Furthermore, a single conductor may have multiple functions, such as wiring, electrodes, and terminals, and in this specification, multiple designations may be used for the same element. Also, even if elements are shown as directly connected in a circuit diagram, they may actually be connected via one or more conductors, and in this specification, such configurations are included in the category of direct connection.

[0028] In this specification, "connection" includes, for example, "electrical connection." The term "electrical connection" is sometimes used to describe the connection relationships of circuit elements as physical objects. Furthermore, "electrical connection" includes both "direct connection" and "indirect connection." "A and B are directly connected" means that A and B are connected without the use of circuit elements (e.g., transistors, switches, etc.; however, wiring is not considered a circuit element). On the other hand, "A and B are indirectly connected" means that A and B are connected through one or more circuit elements.

[0029] For example, assuming a circuit including A and B is in operation, if there is a timing during the circuit's operation when electrical signals are exchanged or potential interactions occur between A and B, then it can be defined that "A and B are indirectly connected" as physical objects. Furthermore, even if there is a timing during the circuit's operation when no electrical signals are exchanged or potential interactions occur between A and B, if there is a timing during the circuit's operation when electrical signals are exchanged or potential interactions occur between A and B, then it can be defined that "A and B are indirectly connected."

[0030] An example of a case where "A and B are indirectly connected" is when A and B are connected via the source and drain of one or more transistors. On the other hand, an example of a case where "A and B are not indirectly connected" is when an insulator is interposed in the path from A to B. Specifically, this includes cases where a capacitive element is connected between A and B, or where a transistor gate insulating film is interposed between A and B. Therefore, it cannot be said that "the gate (A) of a transistor and the source or drain (B) of a transistor are indirectly connected."

[0031] Another example of a situation where it cannot be said that "A and B are indirectly connected" is when multiple transistors are connected via source and drain in the path from A to B, and a constant potential V is supplied to the nodes between the transistors from a power supply, GND, etc.

[0032] (Embodiment 1) This embodiment describes an electronic device according to one aspect of the present invention.

[0033] One aspect of the present invention is an electronic device worn in front of the eye, capable of detecting dynamic information in and around the eye. The electronic device comprises a display device, a reflective / refracting optical system, and a light source. The display device has adjacent light-emitting elements (also called light-emitting devices) and light-receiving elements (also called light-receiving devices) within a pixel. The reflective / refracting optical system forms two different optical paths: one between the surface of the eye and the light-receiving element, and another between the light-emitting element and the retina. The light source functions as a source of infrared light detected by the light-receiving element.

[0034] To improve the accuracy of gaze detection, it is preferable to accurately detect the movement of the eyeball. To accurately detect the precise position of the eye (pupil), it is appropriate to acquire a frontal image of the eye. In one aspect of the present invention, a light-receiving element is provided in the pixel of a display device located in front of the eye, and this light-receiving element is used as a sensor for gaze detection.

[0035] The light emitted by the light-emitting elements of a pixel, which constitutes an image, can be imaged on the retina of the eye by a reflector-refractor optical system. However, with the same optical path, it is not possible to image the light emitted from the surface of the eye (reflected light from a light source) onto the photodetector of the pixel. Therefore, in one embodiment of the present invention, different wavelengths of light are used between the surface of the eye and the photodetector, and between the light-emitting element and the retina, and the optical paths are made different.

[0036] Specifically, visible light is used between the light-emitting element and the retina, and infrared light is used between the surface of the eye and the photodetector. In addition, a half-mirror that transmits light of one wavelength that is not involved in the optical path is used in each optical path. This allows the focal length of each optical path to be adjusted, and with the same reflective / refractive optical system, the light emitted from the light-emitting element can be imaged on the retina, and the light emitted from the surface of the eye can be imaged on the photodetector.

[0037] Therefore, a frontal image of the eye can be acquired, and accurate gaze information can be obtained. In addition, since the light-receiving elements provided in the pixels are used as sensors for gaze detection, the number of components constituting the electronic device can be reduced, enabling miniaturization and cost reduction of the electronic device.

[0038] Furthermore, one embodiment of the present invention, a reflective and refractive optical system, has a configuration in which multiple elements (optical components) are combined. When this configuration is housed in a housing, it is simply called a lens. Alternatively, due to its thin shape, it is sometimes called a pancake lens.

[0039] Figure 1 is a conceptual diagram illustrating the optical path between an element of an electronic device according to one aspect of the present invention and the eyeball. The electronic device is mainly used for VR applications and comprises a display panel 20, a reflective / refracting optical system 30, and a light source 80. In Figure 1, these are shown in a simplified cross-sectional view.

[0040] The display panel 20 is positioned so that its display surface intersects perpendicularly with the optical axis 57 of the reflecting / refracting optical system 30. In this specification, "perpendicular" means a state in which two straight lines form an angle of 85° to 95°. Here, one of the two straight lines refers to the optical axis 57 of the reflecting / refracting optical system 30, and the other refers to a straight line parallel to the display surface.

[0041] The user can view the image displayed on the display panel 20 by bringing their eye 40 close to the vicinity of the reflective / refracting optical system 30. Because the user views the image with a widened field of view provided by the reflective / refracting optical system 30, they can experience a sense of immersion and presence.

[0042] The display panel 20 has pixels 21 on its display surface, and each pixel 21 has a sub-pixel 22 having a light-emitting element and a sub-pixel 23 having a light-receiving element. The light-emitting element is used for display, and the light-receiving element is used to acquire an image of the eye 40 for gaze detection. The reflective / refractive optical system 30 has a half-mirror 33, a half-mirror 34, and a reflective polarizer 36. Note that in Figure 1, elements related to polarization conversion and elements related to light refraction such as lenses are omitted. Details of these will be described later.

[0043] The sub-pixel 22, which has a light-emitting element, emits visible light (VL: solid arrow) to form an image that can be recognized by humans. The visible light emitted from the sub-pixel 22 is repeatedly reflected and refracted within the reflecting and refraction optical system 30, changing its polarization state, and can be formed as an image on the retina 41 of the human eye.

[0044] In this specification, visible light refers to, for example, light with a wavelength range of 360 nm to 830 nm, or light with a wavelength range from blue light to red light emitted by a display device (for example, 450 nm to 780 nm).

[0045] In order to image the eye 40 with the sub-pixel 23 having a light-receiving element, the light emitted from the surface of the eye 40 (for example, the pupil 42) must be imaged by the sub-pixel 23. However, when the sub-pixels 22 and 23, which are adjacent and formed on substantially the same plane within the pixel 21, are used as the starting point, the distance between the surface of the eye 40 and the retina 41 is different. Therefore, with an optical path equivalent to that between the sub-pixel 22 and the retina 41, it is not possible to image the light emitted from the surface of the eye 40 with the sub-pixel 23.

[0046] Therefore, in the space between the surface of the eye 40 and the sub-pixel 23, infrared light (IR: dashed arrow) is used as the light emitted from the surface of the eye 40 (reflected light from the light source 80 onto the surface of the eye 40), and the optical path is made different from that between the sub-pixel 22 and the retina 41 to image the infrared light onto the sub-pixel 23.

[0047] In this way, to use light of two different wavelengths and create different optical paths (focal lengths), half-mirrors are used in each optical path so that the light of one wavelength does not interfere.

[0048] Specifically, as shown in Figure 1, half mirrors 33 located in each optical path are used that transmit visible light (VL) and semi-transmit and semi-reflect infrared light (IR). In addition, half mirrors 34 located in each optical path are used that transmit infrared light (IR) and semi-transmit and semi-reflect visible light (VL).

[0049] The half mirrors 33 and 34 can be given different curvatures, allowing for adjustment of the focal length in each optical path. In Figure 1, the half mirrors 33 and 34 are shown in that order from the display panel 20 side, but they can be swapped.

[0050] Next, the specific configuration of the reflecting and refraction optical system 30 will be explained using Figures 2A and 2B.

[0051] Figures 2A and 2B show a display panel 20 and a reflector / refractor optical system 30 of an electronic device. Figure 2A also shows the optical path of visible light emitted by a sub-pixel 22 and reaching the eye 40. Figure 2B shows the optical path of infrared light emitted by a light source 80 and reaching the sub-pixel 23. Note that the shapes and arrangements of the elements shown in Figures 2A and 2B are examples only.

[0052] The reflective and refractive optical system 30 has a configuration in which a linear polarizer 31, a phase difference plate 32, a half mirror 33, a half mirror 34, a phase difference plate 35, a reflective polarizer 36, and a lens 51 are arranged in this order in one direction from the display panel 20 side, with the optical axis 57 passing through the center of each. The combination of polarizers and phase difference plates (linear polarizer 31 and phase difference plate 32, phase difference plate 35 and reflective polarizer 36) is also called a circular polarizer that converts unpolarized light into circularly polarized light.

[0053] Note that while Figures 2A and 2B show an example where the lens 51 is located between the reflective polarizer 36 and the eye 40, the system is not limited to this. The lens 51 can be placed in other positions. Furthermore, multiple lenses, including lens 51, can be provided. In addition, the lens 51 can be used as a support for other elements of the reflective refractive optical system 30 described above. By using the lens 51 as a support, the number of components in the optical system can be reduced.

[0054] Furthermore, in Figures 2A and 2B, the elements constituting the reflecting and refractionating optical system 30 are shown spaced apart to clarify the explanation of the optical path and polarization state, but this is not the only option. Several adjacent elements can be placed in close proximity to each other. By placing adjacent elements in close proximity, the interface between the elements and the air can be reduced, which can prevent unwanted reflections.

[0055] To create a configuration where adjacent elements are in close proximity, for example, optical contact can be used to arrange two elements in contact without the need for adhesive between them. This reduces the amount of adhesive used and improves heat and chemical resistance. Furthermore, by reducing the number of elements with different refractive indices, unwanted reflections can be prevented.

[0056] It is preferable to bond the elements together using an optical adhesive that has high transmittance with respect to the wavelength of light used (in one embodiment of the present invention, the wavelength range of visible light to infrared light) and does not absorb or birefringe specific polarizations. By adopting such a configuration, properties equivalent to those of an optical contact can be obtained.

[0057] Alternatively, instead of bonding, one element can be formed by attaching it to the other using a coating or other method. Alternatively, a gap can be created between the two elements. This configuration allows for changes in the position of the elements along the optical axis, thus increasing design flexibility.

[0058] Furthermore, an anti-reflective layer can be provided on the surface of a light-transmitting element that has an interface with air. By preventing unwanted reflections at the surface of the element (the interface between the air and the element), the efficiency of light utilization can be improved and the generation of stray light can be suppressed. Note that an anti-reflective layer is not necessary for half mirrors and reflective polarizers, which also have a reflective function.

[0059] As the anti-reflective layer, a film-type anti-reflective coating or a dielectric multilayer coating can be used. For example, on curved surfaces such as the surface of a lens where it is not easy to attach a film, it is preferable to provide a dielectric multilayer coating. Also, for elements with a flat surface, either a film-type anti-reflective coating or a dielectric multilayer coating can be used. However, if the element on which the anti-reflective layer is formed is in the form of a resin film, the element may suffer thermal damage during the formation of the dielectric multilayer coating. In such cases, it is preferable to provide a film-type anti-reflective coating on the element via an adhesive.

[0060] Furthermore, there are two types of anti-reflective films: one that cancels out reflected light through interference, and a moth-eye type that continuously changes the refractive index due to fine protrusions formed on the surface. In either type, it is preferable to use a base film that is not manufactured by the stretching method. Films manufactured using the stretching method may have optical anisotropy, which may change the polarization state. From the perspective of low angle dependence and wavelength dependence, it can be said that it is preferable to use the moth-eye type.

[0061] By using a reflective / refracting optical system 30 with this configuration, the light emitted from the display panel 20 and the light emitted from the surface of the eye 40 can be converted into linearly polarized or circularly polarized light for use, allowing for selective reflection and transmission by elements arranged in the optical path. Therefore, the optical path length can be secured within a limited space, and the reflective / refracting optical system 30 can be made more compact.

[0062] Next, we will describe the details of each element of the display panel 20 and the reflecting / refracting optical system 30.

[0063] As the display panel 20, a liquid crystal panel having liquid crystal elements, an organic EL panel having organic EL elements, or an LED panel having microLEDs can be used. In particular, it is preferable to use an organic EL panel, which is self-emissive and easy to form a high-definition display area. In this specification, a microLED refers to a chip with a chip area of ​​10,000 μm². ２ The following light-emitting diodes are represented. Note that the LED panel is not limited to microLEDs, but for example, a chip with a chip area of ​​10,000 μm². ２ Larger than 1 mm ２ The following light-emitting diodes (also called mini-LEDs) can also be used. If the image quality is acceptable, a larger pixel size can simplify the manufacturing process. In this embodiment, an example using an organic EL panel will be described.

[0064] The linear polarizer 31 can transmit one linearly polarized light from light (unpolarized) that vibrates in all 360° directions. As the linear polarizer 31, for example, a thin film with uniaxially oriented iodine or dye, a wire grid polarizer, or a dielectric multilayer film can be used. It is desirable to use a linear polarizer 31 that supports a wide bandwidth from visible light to infrared light.

[0065] In this explanation, the transmission axis of the linear polarizer 31 is assumed to be 0°, but 0° is not an absolute value, but rather a reference value. In other words, the polarization plane of linearly polarized light transmitted through the linear polarizer 31 is treated as 0°. Therefore, for example, 90° linear polarization in this embodiment means linearly polarized light whose polarization plane is rotated by 90° when transmitted through the linear polarizer 31.

[0066] The phase difference plate 32 has the function of converting linearly polarized light into circularly polarized light. Here, a λ / 4 plate (quarter-wave plate) is used for the phase difference plate 32. When the linear polarizer 31 and the λ / 4 plate are superimposed so that the lagging axis of the λ / 4 plate is 45° with respect to the axis of linearly polarized light emitted from the linear polarizer 31, right-rotating circularly polarized light (right circularly polarized light) is produced. Conversely, when the linear polarizer 31 and the λ / 4 plate are superimposed so that the lagging axis of the λ / 4 plate is -45° with respect to the axis of linearly polarized light emitted from the linear polarizer 31, left-rotating circularly polarized light (left circularly polarized light) is produced. In one embodiment of the present invention, both right-rotating and left-rotating circularly polarized light can be used if the combination with the characteristics of the reflective polarizer 36, which will be described later, is appropriate. There is no difference in the efficiency of light utilization whether right-rotating or left-rotating circularly polarized light is used.

[0067] For example, a dielectric multilayer film can be used for the half mirrors 33 and 34. Here, the half mirror 33 can be a dielectric multilayer film that transmits visible light and semi-transmits and semi-reflects infrared light. Similarly, the half mirror 34 can be a dielectric multilayer film that transmits infrared light and semi-transmits and semi-reflects visible light.

[0068] Figures 3A and 3B show the simulation results of spectral transmittance and spectral reflectance for a glass / dielectric multilayer film / air model when light is incident from the air side. Essential Macleod (manufactured by Thin Film Center Inc.) was used as the simulation software.

[0069] For the dielectric multilayer film, a model was used in which thin films with different refractive indices are stacked in order on the glass substrate, as shown in Table 1. Note that the layer with the higher layer number is the interface side with the glass substrate. As a low refractive index material, for example, silicon oxide (SiO₂) ２ ), magnesium fluoride (MgF２ ), lithium fluoride (LiF) or sodium fluoride (NaF) can be used. As a material with a high refractive index, for example, titanium oxide (TiO ２ ), silicon nitride (SiN), aluminum oxide (Al ２ O ３ ), zirconium oxide (ZrO ２ ), or hafnium oxide (HfO ２ ) can be used.

[0070] Materials that can be used for the dielectric multilayer film preferably select a material with a small attenuation coefficient for the light of the wavelength used among the above in order to minimize optical loss. Also, it is preferable to select a material with small stress and scattering. In the simulation, a dielectric multilayer film using a laminated film of SiO ２ and TiO ２ is assumed.

[0071]

[0072] As shown in FIGS. 3A and 3B, it can be seen that a half mirror that transmits visible light and semi-transmits and semi-reflects infrared light can be formed as the half mirror 33. Also, it can be seen that a half mirror that transmits infrared light and semi-transmits and semi-reflects visible light can be formed as the half mirror 34.

[0073] Note that an antireflection layer (AR layer) corresponding to the wavelength from visible light to infrared light can also be formed by a dielectric multilayer film using the same material. FIG. 3C is a diagram showing the simulation result of the spectral transmittance when the antireflection layer (AR layer) shown in Table 1 is formed on a glass substrate. For improving the light utilization efficiency and reducing stray light, it is preferable to form an antireflection layer (AR layer) on the lens surface in contact with air rather than on the reflective surface.

[0074] As shown in Table 1, since each of the half-mirrors 33 and 34 is an extremely thin dielectric multilayer film, a support is required for their formation. Figures 2A and 2B show an example in which the half-mirror 33 is provided on the first surface of the support 52, and the half-mirror 34 is provided on the surface opposite to the second surface. The positions of the half-mirrors 33 and 34 can also be swapped. Furthermore, the half-mirrors 33 and 34 can be provided on different supports. The material of the support is preferably a material with high transmittance of visible light and infrared light, and can be glass or resin.

[0075] Furthermore, the curved surface of the support 52 allows for curvature to be imparted to both the half mirror 33 and the half mirror 34. For example, as shown in Figures 4A to 4C, the two half mirrors can have concave surfaces in the same direction. Alternatively, as shown in Figures 4D to 4F, the concave surfaces of the half mirror 33 and the half mirror 34 can be in opposite directions. By changing the curvature of the concave surface and the thickness of the support 52, the optical paths of visible light and infrared light can be adjusted, and their respective imaging positions can be changed.

[0076] For example, as shown in Figures 4A and 4D, when the first and second surfaces of the support 52 have the same curvature, the half mirrors 33 and 34 can each be made to act as concave mirrors with the same power. Power refers to the light-gathering force; a positive power value concentrates the light, while a negative power value causes the light to diverge.

[0077] Furthermore, as shown in Figures 4B, 4C, 4E, and 4F, when the first and second surfaces of the support 52 have different curvatures, the half mirrors 33 and 34 can be made to act as concave mirrors, and the power of the half mirrors 33 and 34 can be made different.

[0078] As shown in Figures 1, 2A, and 2B, the optical path from the surface of the eye 40 to the sub-pixel 23 (infrared light path) is shorter than the optical path from the sub-pixel 22 to the retina (visible light path). Therefore, it is preferable to make the curvature of the half-mirror 33 larger than that of the half-mirror 34 (making the radius of curvature of the half-mirror 33 smaller than that of the half-mirror 34). Accordingly, the shape of the support 52 in the reflecting / refracting optical system 30 exemplified in Figures 2A and 2B is more appropriate as shown in Figure 4C or Figure 4F.

[0079] Furthermore, the half-mirror 33 can be provided with multiple concave surfaces, for example, as shown in Figure 4G. By providing multiple concave surfaces in the half-mirror 33, there are multiple imaging positions on the display panel. Therefore, multiple images can be obtained. In addition, since the sub-pixels 23 with imaging functions are not needed in the display panel except at the imaging positions, the degree of freedom in setting the positions where resolution is to be increased (arrangement of sub-pixels 22) can be increased.

[0080] Furthermore, the focal length can be determined not only by the power of the half-mirror acting as a concave mirror, but also by the combined effect of the power of the lens provided in the reflecting / refracting optical system 30. Therefore, in order to obtain a desired focal length, for example, as shown in Figures 4H and 4I, the support 52 and support 53 or support 54 can be used to sandwich one of the half-mirrors 33 or 34. In this case, the support 53 or support 54 can be a plano-concave lens, a biconcave lens, a plano-convex lens, a biconvex lens, a convex meniscus lens, or a concave meniscus lens.

[0081] Alternatively, as shown in Figures 5A to 5I, the half-mirror 33 can be sandwiched between support 53 and support 52, and the half-mirror 34 can be sandwiched between support 52 and support 54. The combination of support 53 and support 54 with different shapes has the following characteristics and can be appropriately selected according to the purpose.

[0082] The Petzval sum, calculated from the refractive index and focal length of each lens, serves as an indicator of field curvature. When the Petzval sum is zero, the image plane becomes flat, which is a desirable characteristic for the lens system. To satisfy this, either the refractive index or the focal length must be negative. Since the refractive index cannot be negative, it is preferable to use a concave lens with a negative focal length. Therefore, to suppress field curvature, it is preferable that one or more of the support 53 and support 54 have the shape of a concave lens.

[0083] Since refraction is accompanied by chromatic aberration, combining positive and negative power is effective in correcting chromatic aberration. Even if the incident surface is flat, chromatic aberration will occur unless the light rays are parallel. Therefore, a combination of surfaces that can correct each other (convex and concave surfaces) is advantageous. Accordingly, to suppress chromatic aberration, it is preferable that the support 53 and support 54 are a combination of a convex lens shape and a concave lens shape.

[0084] Simply put, the greater the positive power, the shorter the focal length can be, and the smaller the overall optical system can be. Even in a configuration where most of the positive power is handled by a half-mirror, the presence of a convex surface allows for an even shorter focal length. Therefore, in order to increase the positive power as much as possible, it is preferable that one or more of the support 53 and support 54 have the shape of a convex lens.

[0085] In a reflective / refractive optical system as described in one aspect of the present invention, polarizers and phase difference plates are required. These are in the form of films, and considering that they are directly attached to the support 53 or support 54, a flat surface for adhesion is advantageous. Therefore, from the viewpoint of ease of manufacturing, it is preferable that one or more of the support 53 and support 54 have a flat surface on the outside.

[0086] In addition, while Figures 4G, 4H, and 5A to 5I illustrate the form of the support 52 shown in Figure 4A, the forms of the support 52 shown in Figures 4B to 4G can also be applied.

[0087] The phase difference plate 35 has the function of reversibly converting linearly polarized and circularly polarized light. Similar to the phase difference plate 32, a λ / 4 plate (quarter-wave plate) can be used as the phase difference plate 35.

[0088] The reflective polarizer 36 can reflect linearly polarized light whose reflection axis and vibration direction coincide, and transmit linearly polarized light perpendicular to the reflection axis. The axis perpendicular to the reflection axis is called the transmission axis. For the reflective polarizer 62, for example, a wire grid polarizer or a dielectric multilayer film can be used. The reflective polarizer 36 is arranged so that its transmission axis is perpendicular to and overlaps with the transmission axis of the linear polarizer 31. This arrangement allows for the creation of two optical paths between the display panel 20 and the eye 40.

[0089] A convex lens can be used for lens 51. For example, a biconvex lens, a plano-convex lens, or a convex meniscus lens can be used as the convex lens. Alternatively, lens 51 can be configured as a combination of multiple lenses selected from biconvex lenses, plano-convex lenses, convex meniscus lenses, biconcave lenses, plano-concave lenses, and concave meniscus lenses. Furthermore, lens 51 is not limited to spherical lenses; aspherical lenses can also be used. Using a combination lens or an aspherical lens can reduce various lens aberrations.

[0090] For the lenses used in the reflecting / refracting optical system 30, it is desirable to use resin lenses to reduce weight. On the other hand, resins have a tendency to exhibit birefringence. In materials with birefringence, the refractive index differs depending on the direction of polarization vibration, so the transmission speed differs for each polarization component. Therefore, after passing through the material, a phase difference occurs between the polarization components, causing a change in the polarization state. In a reflecting / refracting optical system, when a change in the polarization state occurs, light rays that do not pass through the normal optical path are generated. These light rays enter the eye as stray light and are perceived as a double image or a blurred image.

[0091] The relationship between polarization state and optical path will be described later, but for the reasons mentioned above, it is preferable that lenses located in the optical path through which polarized light travels back and forth be made of glass, which exhibits almost no birefringence. Furthermore, since humans cannot perceive polarization, even if a resin lens with birefringence is used in the lens positioned directly in front of the eye 40, there will be no problem in the visibility of the display.

[0092] For example, acrylic resin, polycarbonate resin, polyester resin, and cycloolefin resin are known to be used as resins for lenses, and these can typically be used as lens materials. Furthermore, if a material with sufficiently low birefringence is used, resin lenses can also be used in the optical path on which polarized light travels back and forth.

[0093] Next, we will explain the optical path of the visible light emitted by the sub-pixel 22 shown in Figure 2A.

[0094] Some of the light emitted from the sub-pixels 22 of the display panel 20 passes through the linear polarizer 31, the phase difference plate 32, and the half mirror 33, partially passes through the half mirror 34, passes through the phase difference plate 35, and is reflected by the reflective polarizer 36. The light reflected by the reflective polarizer 36 passes through the phase difference plate 35 and is partially reflected by the half mirror 34. The light partially reflected by the half mirror 34 passes through the phase difference plate 35, the reflective polarizer 36, and the lens 51, enters the eye 40, and forms an image on the retina 41.

[0095] In this way, by repeatedly reflecting within the reflective / refracting optical system 30, the optical path length can be secured, making it possible to create an optical system with a short focal length.

[0096] The details of the optical path, including the polarization state, will now be explained. Light (unpolarized) vibrating in all 360° directions emitted from the display panel 20 is incident on the linear polarizer 31. The transmission axis of the linear polarizer 31 is 0°, and 0° linearly polarized light is emitted from the linear polarizer 31. If a liquid crystal panel is used for the display panel 20, the linear polarizer 31 can be used as one of the pair of polarizers that the liquid crystal panel has.

[0097] The 0° linearly polarized light emitted from the linear polarizer 31 is converted to left-circularly polarized light (L) by the phase difference plate 32. The left-circularly polarized light (L) passes through the half mirror 33, partially passes through the half mirror 34, and is incident on the phase difference plate 35, where it is converted back to 0° linearly polarized light. Here, we describe an example where the light emitted from the phase difference plate 32 is left-circularly polarized, but it can also be right-circularly polarized.

[0098] The 0° linearly polarized light emitted from the phase difference plate 35 is reflected by the reflective polarizer 36 with a reflection axis of 0°, incident on the phase difference plate 35, and converted to left circularly polarized light (L). The left circularly polarized light (L) is partially reflected by the half mirror 34, and its polarity is reversed to right circularly polarized light (R). The right circularly polarized light (R) is incident on the phase difference plate 35 and converted to 90° linearly polarized light. The 90° linearly polarized light passes through the reflective polarizer 36 and lens 51 with a transmission axis of 90° and is incident on the eye 40.

[0099] Next, we will explain the optical path of infrared light emitted from the surface of the eye 40 shown in Figure 2B.

[0100] Infrared light (IR) emitted from the light source 80 travels toward the eye 40 and reaches the eye 40 or its vicinity. A portion of the infrared light (IR) is reflected by the eye 40 or its vicinity and travels toward the reflectivity optical system 30, reaching the sub-pixel 23. In this way, the infrared light (IR) emitted by the light source 80 and reflected by the eye 40 or its vicinity can be detected by the sub-pixel 23, which has a photodetector, and by periodically acquiring an image of the eye 40, dynamic information of the eye 40 can be obtained.

[0101] Furthermore, by acquiring images of the vicinity of the eye 40, it is possible to detect the number of blinks per unit time and the blinking speed. The number and speed of blinks are said to be related to fatigue levels, and it is also possible to detect fatigue levels by detecting information related to blinking.

[0102] Furthermore, it is preferable to use near-infrared light (for example, light with a wavelength of 780 nm to 2 μm) with relatively high energy, as the light emitted by the light source 80 is infrared light with low visual sensitivity that has little impact on visibility, and is easily converted into photoelectric energy by the photodetector.

[0103] Furthermore, it is preferable that the infrared light (IR) irradiated from the light source 80 to the eye 40 is linearly polarized and passes through the reflective polarizer 36. When unpolarized infrared light (IR) is irradiated to the eye 40, the amount of light transmitted through the reflective polarizer 36 is reduced to about 40% due to reflection and absorption. Considering the loss due to the half-mirror in the subsequent optical path, the amount of light reaching the sub-pixel 23 is about 10%, making it difficult to obtain a clear image. Increasing the amount of light emitted from the light source 80 will relatively increase the amount of light reaching the sub-pixel 23, but strong light irradiation may have adverse effects on the human body.

[0104] On the other hand, if the infrared light (IR) irradiated from the light source 80 to the eye 40 is linearly polarized and passes through the reflective polarizer 36, then the linearly polarized component of the light reflected by the eye 40 that passes through the reflective polarizer 36 can be transmitted 100% through the reflective polarizer 36. Considering the subsequent loss due to the half-mirror, the amount of light reaching the sub-pixel 23 is about 25%. In other words, if the amount of light irradiated from the light source 80 to the eye 40 is the same, it is easier to obtain a clearer image using a specific linear polarization than using unpolarized light.

[0105] Therefore, as shown in Figure 6A, it is preferable to provide a linear polarizing plate 81 between the light source 80 and the eye 40. For example, if the transmission axis of the reflective polarizing plate 36 is 90°, the transmission axis of the linear polarizing plate 81 should also be 90°. Alternatively, as shown in Figure 6B, a mirror 55 can be placed between the light source 80 and the eye 40. By placing the mirror 55, the degree of freedom in the placement position of the light source 80 can be increased. Note that the placement position of the linear polarizing plate 81 is not limited as long as it is within the optical path from the light source 80 to the eye 40. Also, as shown in Figures 6C and 6D, a reflective polarizing plate 36 can be used instead of the linear polarizing plate 81 by extending it to the vicinity of the placement position of the light source 80.

[0106] A portion of the light emitted from the light source 80 and reflected from the surface of the eye 40 passes through the lens 51, reflective polarizer 36, phase difference plate 35, and half mirror 34, and is partially reflected by the half mirror 33. The light partially reflected by the half mirror 33 passes through the half mirror 34 and phase difference plate 35, and is reflected by the reflective polarizer 36. The light reflected by the reflective polarizer 36 passes through the phase difference plate 35 and the half mirror 34, partially passes through the half mirror 33, passes through the phase difference plate 32 and linear polarizer 31, and is imaged by the sub-pixel 23.

[0107] The details of the optical path, including the polarization state, will be explained further. In the following explanation, the light emitted from the surface of eye 40 will be assumed to be 90° linearly polarized.

[0108] 90° linearly polarized light emitted from the surface of the eye 40 passes through the lens 51 and the reflective polarizer 36 with a transmission axis of 90°, is incident on the phase difference plate 35, and is converted to right circularly polarized light (R). The right circularly polarized light (R) passes through the half mirror 34, is partially reflected by the half mirror 33, and its polarity is reversed to left circularly polarized light (L).

[0109] Left-circularly polarized light (L) passes through the half-mirror 34 and is incident on the phase difference plate 35, where it is converted to 0° linearly polarized light. The 0° linearly polarized light is reflected by the reflective polarizer 36 with a reflection axis of 0°, and is incident on the phase difference plate 35, where it is converted to left-circularly polarized light (L).

[0110] Left circularly polarized light (L) is transmitted through half mirror 34, partially transmitted through half mirror 33, and incident on phase difference plate 32, where it is converted to 0° linearly polarized light. The 0° linearly polarized light is transmitted through linear polarizer plate 31 with a transmission axis of 0° and incident on sub-pixel 23.

[0111] In this way, by utilizing linearly polarized and circularly polarized light, as well as half-mirrors and reflective polarizers, reflection and transmission can be selectively performed. Therefore, the optical path length can be secured within a limited space, and the focal length of optical instruments can be shortened.

[0112] In the above description, we explained a configuration in which two optical paths are formed using two half-mirrors with different characteristics. However, two optical paths can also be formed by using two reflective polarizers with different characteristics.

[0113] Figures 7A and 7B show examples of a reflective-refractive optical system 30 using two reflective polarizers with different characteristics. The differences from the configuration in Figures 2A and 2B are that half mirrors 33 and 34 become one half mirror 37, and reflective polarizer 36 becomes two reflective polarizers 38 and 39. In the following explanation, the explanation of elements common to Figures 2A and 2B will be omitted.

[0114] The half-mirror 37 has semi-transmitting and semi-reflective properties in the range from visible light to infrared light. The reflective polarizer 38 has the properties of transmitting infrared light, reflecting 0° linearly polarized visible light, and transmitting 90° linearly polarized visible light. The reflective polarizer 39 has the properties of transmitting visible light, reflecting 0° linearly polarized infrared light, and transmitting 90° linearly polarized infrared light.

[0115] The reflective / refractive optical system 30 has a configuration in which a linear polarizer 31, a phase difference plate 32, a half mirror 37, a phase difference plate 35, a reflective polarizer 38, a reflective polarizer 39, and a lens 51 are arranged in this order in one direction from the display panel 20 side.

[0116] Next, we will explain the optical path of the visible light emitted by the sub-pixel 22 shown in Figure 7A.

[0117] Some of the light emitted from the sub-pixels 22 of the display panel 20 passes through the linear polarizer 31 and the phase difference plate 32, partially passes through the half mirror 37, passes through the phase difference plate 35, and is reflected by the reflective polarizer 36. The light reflected by the reflective polarizer 38 passes through the phase difference plate 35 and is partially reflected by the half mirror 37. The light partially reflected by the half mirror 37 passes through the phase difference plate 35, the reflective polarizer 38, the reflective polarizer 39 and the lens 51, enters the eye 40, and forms an image on the retina 41.

[0118] Light (unpolarized) vibrating in all 360° directions emitted from the display panel 20 is incident on the linear polarizer 31. The transmission axis of the linear polarizer 31 is 0°, and 0° linearly polarized light is emitted from the linear polarizer 31. When a liquid crystal panel is used for the display panel 20, the linear polarizer 31 can be used as one of a pair of polarizers in the liquid crystal panel.

[0119] The 0° linearly polarized light emitted from the linear polarizer 31 is converted to left-circularly polarized light (L) by the phase difference plate 32. The left-circularly polarized light (L) is partially transmitted through the half mirror 37 and incident on the phase difference plate 35, where it is converted back to 0° linearly polarized light. Here, we describe an example where the light emitted from the phase difference plate 32 is left-circularly polarized, but it can also be right-circularly polarized.

[0120] The 0° linearly polarized light emitted from the phase difference plate 35 is reflected by the reflective polarizer 38 with a reflection axis of 0°, incident on the phase difference plate 35, and converted to left circularly polarized light (L). The left circularly polarized light (L) is partially reflected by the half mirror 37, and its polarity is reversed to right circularly polarized light (R). The right circularly polarized light (R) is incident on the phase difference plate 35 and converted to 90° linearly polarized light. The 90° linearly polarized light passes through the reflective polarizer 36 with a transmission axis of 90°, the reflective polarizer 39 that transmits visible light, and the lens 51, and is incident on the eye 40.

[0121] Next, we will explain the optical path of infrared light emitted from the surface of the eye 40 shown in Figure 7B.

[0122] A portion of the light emitted from the light source 80 and reflected from the surface of the eye 40 passes through the lens 51, reflective polarizer 39, reflective polarizer 38, and phase difference plate 35, and is partially reflected by the half mirror 37. The light partially reflected by the half mirror 37 passes through the phase difference plate 35 and reflective polarizer 38, and is reflected by the reflective polarizer 39. The light reflected by the reflective polarizer 39 passes through the reflective polarizer 38 and phase difference plate 35, partially passes through the half mirror 37, passes through the phase difference plate 32 and linear polarizer 31, and is imaged by the sub-pixel 23. In the following description, the light emitted from the surface of the eye 40 is assumed to be 90° linearly polarized.

[0123] 90° linearly polarized light emitted from the surface of the eye 40 passes through the lens 51, the reflective polarizer 39 with a transmission axis of 90°, and the reflective polarizer 38 that transmits infrared light, and is incident on the phase difference plate 35, where it is converted to right-circularly polarized light (R). The right-circularly polarized light (R) is partially reflected by the half mirror 37, and its polarity is reversed to left-circularly polarized light (L).

[0124] Left-circularly polarized light (L) is incident on the phase difference plate 35 and converted to 0° linearly polarized light, passes through the reflective polarizer plate 38, is reflected by the reflective polarizer plate 36 with a reflection axis of 0°, passes through the reflective polarizer plate 38, is incident on the phase difference plate 35 and converted to left-circularly polarized light (L).

[0125] Left-circularly polarized light (L) partially passes through the half-mirror 37 and is incident on the phase difference plate 32, where it is converted to 0° linearly polarized light. The 0° linearly polarized light passes through the linear polarizer plate 31 with a transmission axis of 0° and is incident on the sub-pixel 23.

[0126] Thus, two optical paths can be formed by using two reflective polarizers with different characteristics. Furthermore, as shown in Figures 8A and 8B, two optical paths can also be established by swapping the positions of reflective polarizer 38 and reflective polarizer 39.

[0127] Furthermore, while the above describes a form of reflective / refractive optical system that can be used mainly in electronic devices for VR applications, one aspect of the present invention can also be applied to reflective / refractive optical systems in electronic devices for AR applications.

[0128] Figure 9 is a conceptual diagram illustrating the optical path between the elements of an electronic device for augmented reality (AR) applications and the eyeball. The electronic device includes a display panel 20, a reflective / refracting optical system 60, and a light source 80. Figure 9 shows a simplified cross-section of these components.

[0129] The AR electronic device illustrated in Figure 9 is designed to be viewed by superimposing an image from the display panel 20 onto ambient light. The display light (visible light VL1) from the display panel 20 and the ambient light (visible light VL2) can be incident on the eye 40 via a beam splitter (reflective polarizer 62) that is installed at an angle. In addition, the light emitted from the surface of the eye 40 (infrared light IR) can be incident on the light-receiving element of the display panel 20 via the beam splitter (reflective polarizer 62).

[0130] The display panel 20 has pixels 21 on its display surface, and each pixel 21 has a sub-pixel 22 having a light-emitting element and a sub-pixel 23 having a light-receiving element. The light-emitting element is used for display, and the light-receiving element is used to acquire an image of the eye 40 for gaze detection. The reflective-refractive optical system 60 has a half-mirror 65, a half-mirror 64, and a reflective polarizer 62. Note that in Figure 9, elements related to polarization conversion and elements related to light refraction such as lenses are omitted.

[0131] In AR electronic devices, the configuration differs from the reflecting / refracting optical system 30 shown in Figures 1 to 2A and 2B because an optical path is provided to take in ambient light. However, it is common to both that infrared light (IR) is used between the surface of the eye 40 and the sub-pixels 23, and that a half-mirror is used that transmits one type of light that is not involved in the optical path. The half-mirror 64 transmits infrared light (IR) and can semi-transmit and semi-reflect visible light (VL1, VL2). The half-mirror 65 transmits visible light (VL1, VL2) and can semi-transmit and semi-reflect infrared light (IR).

[0132] Next, the specific configuration of the reflecting and refraction optical system 60 will be explained using Figures 10A, 10B, and 10C. Note that explanations of elements common to the configurations in Figures 1, 2A, and 2B will be omitted.

[0133] Figures 10A to 10C show a display panel 20 and a reflector / refractor optical system 60 of an electronic device. Figure 10A shows the optical path of visible light emitted by a sub-pixel 22. Figure 10B shows the optical path of infrared light emitted by a light source 80 and reaching a sub-pixel 23. Figure 10C shows the optical path of ambient light. Note that the shapes and arrangements of the elements shown in Figures 10A and 10B are examples only.

[0134] The reflective-refractive optical system 60 includes a linear polarizer 61, a reflective polarizer 62, a phase difference plate 63, a half mirror 64, a half mirror 65, a phase difference plate 66, a linear polarizer 67, and a lens 58. The linear polarizer 61 and lens 58 are provided between the display panel 20 and the reflective polarizer 62. The reflective polarizer 62 is provided so that its reflective surface is oblique in a linear direction perpendicular to the display surface of the display panel 20. The phase difference plate 63, half mirror 64, half mirror 65, phase difference plate 66, and linear polarizer 67 are provided in order from the reflective polarizer 62 side in the direction in which the reflected light propagates.

[0135] The half-mirrors 64 and 65 can be given different curvatures, allowing for adjustment of the focal length in each optical path. In Figures 10A to 10C, the half-mirrors 64 and 65 are shown in that order from the reflective polarizer 62 side, but they can be swapped. By changing the curvature of the half-mirrors and the thickness of the support 56, the optical paths of visible light and infrared light can be adjusted, and their respective imaging positions can be changed.

[0136] Figures 10A to 10C show an example where the lens 58 is positioned between the linear polarizer 61 and the reflective polarizer 62, but the system is not limited to this. The lens 58 can be placed in other positions as appropriate depending on the required optical properties. In addition, multiple lenses, including lens 58, can be provided. For example, a lens can be placed between the eye 40 and the reflective polarizer 62. A lens can also be placed on the outside of the linear polarizer 67 (the side into which ambient light enters). Such a lens can provide the optical system with a visual correction effect against ambient light (acting like eyeglasses).

[0137] Furthermore, the lens 58 and the like can also be used as supports for other elements of the reflecting and refraction optical system 60 described above. Also, the support 56 can have a curved surface that adjusts the curvature of the half mirrors 64 and 65, similar to the support 52 shown in Figures 4A to 5I. In addition, supports similar to the support 53 and 54 shown in Figures 4A to 5I can be provided on either or both of the outside of the half mirror 64 and the outside of the half mirror 65.

[0138] Furthermore, in Figures 10A to 10C, the elements constituting the reflecting and refraction optical system 60 are shown spaced apart to clarify the explanation of the optical path and polarization state, but this is not the only option. Several adjacent elements can be placed in close proximity to each other. By placing elements in close proximity, the interface between the lens and the air can be reduced, thereby preventing unwanted reflections.

[0139] Next, we will explain the optical path of the visible light emitted by the sub-pixel 22 shown in Figure 10A.

[0140] A portion of the light (VL1) emitted from the sub-pixels 22 of the display panel 20 passes through the linear polarizer 31 and the lens 58, and is reflected by the reflective polarizer 62. The light reflected by the reflective polarizer 62 passes through the phase difference plate 63 and is partially reflected by the half mirror 64. The light partially reflected by the half mirror 64 passes through the phase difference plate 63 and the reflective polarizer 62, enters the eye 40, and forms an image on the retina 41.

[0141] In this way, by repeatedly reflecting within the reflective / refracting optical system 60, the optical path length can be secured, making it possible to create an optical system with a short focal length.

[0142] Light (unpolarized) vibrating in all 360° directions emitted from the display panel 20 is incident on the linear polarizer 61. The transmission axis of the linear polarizer 61 is 0°, and 0° linearly polarized light is emitted from the linear polarizer 61. When a liquid crystal panel is used for the display panel 20, the linear polarizer 61 can be used as one of a pair of polarizers in the liquid crystal panel.

[0143] The 0° linearly polarized light emitted from the linear polarizer 61 is reflected by the reflective polarizer with a reflection axis of 0° and converted to left-circularly polarized light (L) by the phase difference plate 63. The left-circularly polarized light (L) is partially reflected by the half-mirror 64 and its polarity is reversed to right-circularly polarized light (R). The right-circularly polarized light (R) is incident on the phase difference plate 63 and converted to 90° linearly polarized light. The 90° linearly polarized light passes through the reflective polarizer 62 with a transmission axis of 90° and is incident on the eye 40. Note that this explanation describes an example where the light emitted from the phase difference plate 63 is left-circularly polarized, but it can also be right-circularly polarized.

[0144] Next, the optical path of infrared light emitted from the surface of the eye 40 shown in Figure 10B will be described. Here, the light emitted from the eye 40 is assumed to be 90° linearly polarized.

[0145] Infrared light (IR) emitted from the light source 80 travels toward the eye 40 and reaches the eye 40 or its vicinity. A portion of the infrared light (IR) is reflected by the eye 40 or its vicinity and travels toward the reflectivity optical system 60, reaching the sub-pixel 23. In this way, the infrared light (IR) emitted by the light source 80 and reflected by the eye 40 or its vicinity can be detected by the sub-pixel 23, which has a photodetector, and by acquiring an image of the eye 40, dynamic information of the eye 40 can be obtained.

[0146] The 90° linearly polarized light emitted from the light source 80 and reflected from the surface of the eye 40 passes through the reflective polarizer 62 and the phase difference plate 63, both with a transmission axis of 90°, and is converted to right-circularly polarized light (R). The right-circularly polarized light (R) passes through the half mirror 64 and is partially reflected by the half mirror 65, where its polarity is reversed to left-circularly polarized light (L). The left-circularly polarized light (L) passes through the phase difference plate 63 and is converted to 0° linearly polarized light. The 0° linearly polarized light is reflected by the reflective polarizer 62 with a reflection axis of 0°, passes through the lens 58 and the linear polarizer 61, and is incident on the sub-pixel 23.

[0147] In this way, by utilizing linearly polarized and circularly polarized light, as well as half-mirrors and reflective polarizers, reflection and transmission can be selectively performed. Therefore, the optical path length can be secured within a limited space, and the focal length of optical instruments can be shortened.

[0148] Next, the optical path of ambient light shown in Figure 10C will be explained. Ambient light (VL2) is taken in from the side of the linear polarizer 67 opposite to the phase difference plate 66. Ambient light (VL2) is light (unpolarized) that vibrates in all 360° directions and is incident on the linear polarizer 67. The transmission axis of the linear polarizer 67 is 90°, and 90° linearly polarized light is emitted from the linear polarizer 67.

[0149] 90° linearly polarized light is incident on the phase difference plate 66 and converted to right-circularly polarized light (R). The right-circularly polarized light (R) passes through the half mirror 65, partially passes through the half mirror 64, passes through the phase difference plate 63 and is converted to 90° linearly polarized light. The 90° linearly polarized light passes through the reflective polarizer 62 with a transmission axis of 90° and is incident on the eye 40.

[0150] In this way, by utilizing linearly polarized and circularly polarized light, as well as half-mirrors and reflective polarizers, reflection and transmission can be selectively performed. Therefore, the optical path length can be secured within a limited space, and the focal length of optical instruments can be shortened.

[0151] Figure 11A is a diagram illustrating a display panel 20 of an electronic device according to one embodiment of the present invention. The display panel 20 has a pixel array 14, and circuits 15, 16, 17, 18, and 19. The pixel array 14 has pixels 21 arranged in the column direction and row direction.

[0152] Pixel 21 may have sub-pixels 22 and 23. For example, sub-pixel 22 has the function of emitting display light. Sub-pixel 23 has the function of detecting light irradiated onto the display panel 20.

[0153] In this specification, the smallest unit in which an independent operation takes place within a single "pixel" is conveniently defined as a "sub-pixel" for explanation purposes. However, it is also possible to replace "pixel" with "region" and "sub-pixel" with "pixel".

[0154] The sub-pixel 22 has a light-emitting element that emits visible light. Preferably, an EL element such as an OLED (Organic Light Emitting Diode) or QLED (Quantum-dot Light Emitting Diode) is used as the light-emitting element. Examples of light-emitting materials for EL elements include fluorescent materials, phosphorescent materials, thermally activated delayed fluorescence (TADF) materials, and inorganic compounds (such as quantum dot materials). In addition, LEDs such as microLEDs (Micro Light Emitting Diodes) can also be used as the light-emitting element.

[0155] The sub-pixel 23 has a photodetector that is sensitive to infrared light. For example, near-infrared light can be used as the infrared light. The photodetector can be a photoelectric conversion element that detects incident light and generates an electric charge. In the photodetector, the amount of charge generated is determined based on the amount of incident light. For example, a pn-type or PIN-type photodiode can be used as the photodetector.

[0156] As the light-receiving element, it is preferable to use an organic photodiode having an organic compound in its photoelectric conversion layer. Organic photodiodes are easy to make thin, light, and large in area. Also, because they offer a high degree of freedom in shape and design, they can be applied to various display devices. Alternatively, a photodiode using crystalline silicon (monocrystalline silicon, polycrystalline silicon, microcrystalline silicon, etc.) can also be used as the light-receiving element.

[0157] In one aspect of the present invention, an organic EL element is used as the light-emitting element, and an organic photodiode is used as the light-receiving element. The organic photodiode can also have a configuration that has elements common to the organic EL element. Therefore, the light-receiving element can be incorporated into the display panel 20 without significantly increasing the manufacturing process. For example, the photoelectric conversion layer of the light-receiving element and the light-emitting layer of the light-emitting element can be manufactured separately, while the remaining layers can include the same configuration for both the light-emitting element and the light-receiving element. By adopting such a configuration, the manufacturing process can be reduced.

[0158] Circuits 15 and 16 are driver circuits for driving the sub-pixels 22. Circuit 15 can function as a source driver, and circuit 16 can function as a gate driver. Circuits 15 and 16 can use, for example, shift register circuits. The driving circuits for sub-pixels 22 and 23 can also be separated. This allows for, for example, different timing for the operation of the light-emitting element and the photodetector. Alternatively, the frame rates for the light emission operation and the imaging operation can be set separately.

[0159] Circuits 17 and 18 are driver circuits for driving the sub-pixels 23. Circuit 17 can function as a column driver, and circuit 18 can function as a row driver. Circuits 17 and 18 can be, for example, shift register circuits or decoder circuits.

[0160] Circuit 19 is a data readout circuit for the data output by the sub-pixel 23. Circuit 19, for example, has an A / D conversion circuit and has the function of converting the analog data output from the sub-pixel 23 into digital data. Circuit 19 may also have a CDS circuit that performs correlated double sampling on the output data. By using a CDS circuit, noise can be reduced.

[0161] As shown in Figure 11B, circuits 15 to 19 can also be configured to overlap with the pixel array 14. This configuration allows for the creation of a narrow-bezel display device. Furthermore, by having the drive circuits located below the pixel array 14, wiring length and wiring capacitance can be reduced. Therefore, a display device that can operate at high speed and with low power consumption can be created. Note that the arrangement and area of ​​circuits 15 to 19 shown in Figure 11B are just an example and can be changed as appropriate. In addition, some of circuits 15 to 19 can be formed on the same layer as the pixel array 14.

[0162] In this configuration, for example, circuits 15 to 19 can be formed using transistors (hereinafter referred to as Si transistors) fabricated on a single-crystal silicon substrate, and the pixel circuits of the pixel array 14 can be formed using transistors (hereinafter referred to as OS transistors) having a metal oxide in the channel formation region. OS transistors can be formed as thin films and can be formed by stacking them on top of Si transistors.

[0163] The sub-pixel 23 has a light-receiving element that can be used to acquire imaging data such as eye movements or changes in pupil diameter. By analyzing this image data, gaze detection can be performed. By detecting the gaze, it can function as an input interface. Alternatively, foveal rendering can be applied. Furthermore, the light-receiving element can be used to acquire imaging data such as the iris. In other words, a biometric authentication function can be added to the display device.

[0164] Figures 11C to 11E illustrate examples of sub-pixel layouts within a pixel 21. Figure 11A shows an example where one sub-pixel 22 and one sub-pixel 23 are placed within a pixel 21. However, as shown in Figure 11C, a sub-pixel 22R with a red light-emitting element, a sub-pixel 22G with a green light-emitting element, and a sub-pixel 22B with a blue light-emitting element can also be placed within the pixel 21. This configuration enables color display.

[0165] Note that while Figure 11C shows a layout in which sub-pixels 22R, 22G, 22B, and 23 are arranged vertically and horizontally, the layout shown in Figure 11D can also be used.

[0166] Furthermore, as shown in Figure 11E, a sub-pixel 22W having a light-emitting element that emits white light can also be provided. Since the sub-pixel 22W can emit white light on its own, the luminescence of sub-pixels of other colors can be suppressed when displaying white or a color close to white. Therefore, display can be performed with low power consumption.

[0167] Furthermore, the arrangement of the subpixels shown in Figures 11C to 11E can be rearranged. Also, the configuration of pixels and subpixels is not limited to those described above, and various arrangements can be adopted.

[0168] For example, as shown in Figures 12A and 12B, it is also possible to create a pixel 21a having sub-pixels 22 (sub-pixels 22R, 22G, 22B) and a pixel 21b having sub-pixels 22 (sub-pixels 22R, 22G, 22B) and sub-pixel 23.

[0169] When pixels 21a and 21b are created in this manner, pixels 21a and 21b can be arranged alternately, as shown in Figure 12C. Alternatively, one pixel 21b can be placed for every multiple pixels 21a. Since the subpixels 22 constitute an image, it is preferable to arrange them at a high density, but when acquiring the position information of the eye 40, a resolution higher than necessary is not required. Therefore, the number of pixels 21b having subpixels 23 can be less than the number of pixels 21a.

[0170] Furthermore, as shown in Figure 12D, pixels 21a can be placed in region 25 near the center of the pixel array 14, and pixels 21b can be placed in region 26 outside of region 25. Region 26 is often outside the central field of vision, where the resolution of the human eye is relatively low, so even if the resolution is reduced, it is difficult for people to recognize. On the other hand, region 25 is often at the center of the field of vision, where the resolution of the human eye is high. Therefore, it is preferable to place region 25 near the center of the pixel array 14 and display at high resolution.

[0171] Furthermore, as shown in Figure 13A, an aperture 59 that transmits visible light (VL) and partially transmits infrared light (IR) can be provided, allowing light emitted from a part of the eye 40 to preferentially reach the sub-pixels 23. Since light that does not participate in imaging and arrives from various locations also reaches the sub-pixels 23, image blurring can occur. By providing the aperture 59, unwanted light can be blocked, and light emitted from a part of the eye 40 can preferentially reach the sub-pixels 23, thereby suppressing image blurring.

[0172] Figures 13B to 13G illustrate combinations of the pixel array 14 and the aperture 59. The aperture 59 can take various forms, and as shown in Figure 12D, infrared (IR) light-transmitting regions 59T are provided according to the arrangement of regions 26 within the pixel array 14.

[0173] For example, as shown in Figure 13A, if the line connecting the eye 40 and the center of the display panel 20 coincides with the optical axis of the reflecting / refracting optical system 30, a transparent region 59T is provided near the center of the aperture 59, as shown in Figure 13B. In this case, it is preferable to provide region 26 in the pixel array 14 so that it has an area that overlaps with the transparent region 59T.

[0174] Furthermore, since the center of the display panel 20 is often within the range of the central field of view, it is also effective to increase the resolution by placing a region 25 in the central part of the display panel 20, as shown in Figure 12D. In this case, it is preferable to provide a transparent region 59T outside the center of the aperture 59, as shown in Figure 13C.

[0175] Furthermore, as shown in Figures 13D and 13E, the aperture 59 can have multiple transmission regions 59T. If the line connecting the eye 40 and the center of the display panel 20 does not coincide with the optical axis of the reflection / refractive optical system 30, an image off-center from the eye 40 will be captured. Therefore, as shown in Figures 13D and 13E, by having multiple transmission regions 59T and capturing images using the light transmitted through each, multiple images off-center from the eye 40 can be captured. By combining these multiple images, an image of the entire eye 40 can be obtained. When the aperture 59 has multiple transmission regions 59T, it is preferable to apply a configuration in which the concave surfaces of the half mirror 33 shown in Figure 4G are multiple (the same number as the transmission regions 59T).

[0176] Furthermore, as shown in Figures 13F and 13G, a region 25 can be provided near the center of the pixel array 14, and a region 27 outside of it can be provided in which pixels having only photoreceiving elements are arranged. Even if a light-emitting element is provided in a region outside the viewing angle of the electronic device, a person cannot see the display, but by adjusting the optical path, it is possible to image the eye 40 with the photoreceiving elements in that region. Therefore, in the pixel array 14, pixels having only photoreceiving elements can be provided in a region outside the viewing angle of the electronic device.

[0177] In Figures 13B to 13G, examples are shown where the shapes of region 25, region 26, and the transmission region 59T are circular or square, but they are not limited to these. For example, they can be elliptical or polygonal. The sizes of region 26 and the transmission region 59T can be appropriately determined by the path of infrared light. The aperture 59 can be formed by partially providing a dielectric multilayer film on a support that transmits visible light and infrared light.

[0178] Next, we will describe examples of pixel circuits for sub-pixels having light-emitting elements and pixel circuits for sub-pixels having light-receiving elements.

[0179] Figure 14A shows an example of a pixel circuit PIX1 applicable to the sub-pixel 22. A similar circuit can also be used for the light source 80. The pixel circuit PIX1 includes a light-emitting element EL1, transistors M1, M2, M3, and capacitor C1. Here, an example using a light-emitting diode as the light-emitting element EL1 is shown. It is preferable to use an organic EL element that emits visible light for the light-emitting element EL1.

[0180] Transistor M1 has its gate connected to wiring G1, one of its source or drain connected to wiring S1, and the other of its source or drain connected to one electrode of capacitor C1 and the gate of transistor M2. One of the source or drain of transistor M2 is connected to wiring V2, and the other is connected to the other electrode of capacitor C1, the anode of light-emitting element EL1, and one of the source or drain of transistor M3. Transistor M3 has its gate connected to wiring G2, and the other of its source or drain connected to wiring V0. The cathode of light-emitting element EL1 is connected to wiring V1.

[0181] A constant potential is supplied to wiring V1 and wiring V2, respectively. Light emission can be achieved by setting the anode side of the light-emitting element EL1 to a high potential and the cathode side to a low potential. Transistor M1 is controlled by the signal supplied to wiring G1 and functions as a selection transistor to control the selected state of the pixel circuit PIX1. Transistor M2 functions as a drive transistor that controls the current flowing to the light-emitting element EL1 according to the potential supplied to the gate.

[0182] When transistor M1 is conducting, the potential supplied to wiring S1 is supplied to the gate of transistor M2, and the luminescence brightness of the light-emitting element EL1 can be controlled according to that potential. Transistor M3 is controlled by a signal supplied to wiring G2. This allows the potential between transistor M3 and the light-emitting element EL1 to be reset to a constant potential supplied from wiring V0, and the potential can be written to the gate of transistor M2 while the source potential of transistor M2 is stabilized.

[0183] Figure 14B shows an example of a circuit PIX2 applicable to the sub-pixel 23. Circuit PIX2 includes a photodetector PD1, transistors M4, M5, M6, M7, and capacitor C2. Here, an example is shown in which a photodiode is used as the photodetector PD1.

[0184] The photodetector PD1 has its cathode connected to wiring V1 and its anode connected to either the source or drain of transistor M4. Transistor M4 has its gate connected to wiring G3 and its other source or drain connected to one electrode of capacitor C2, either the source or drain of transistor M5, and the gate of transistor M6. Transistor M5 has its gate connected to wiring G4 and its other source or drain connected to wiring V3. Transistor M6 has one source or drain connected to wiring V4 and its other source or drain connected to either the source or drain of transistor M7. Transistor M7 has its gate connected to wiring G5 and its other source or drain connected to wiring OUT.

[0185] A constant potential is supplied to wiring V1, wiring V3, and wiring V4, respectively. When the photodetector PD1 is driven with reverse bias, a potential lower than the potential of wiring V1 is supplied to wiring V3. Transistor M5 is controlled by a signal supplied to wiring G5 and has the function of resetting the potential of the node connected to the gate of transistor M6 to the potential supplied to wiring V3. Transistor M4 is controlled by a signal supplied to wiring G3 and has the function of controlling the timing at which the potential of the node changes according to the current flowing through the photodetector PD1. Transistor M6 functions as an amplifying transistor that provides an output according to the potential of the node. Transistor M7 is controlled by a signal supplied to wiring G6 and functions as a selection transistor for reading out the output according to the potential of the node with an external circuit connected to wiring OUT.

[0186] Furthermore, as a modified version of circuit PIX2, circuit PIX3 shown in Figure 14C can also be used. Circuit PIX3 differs from circuit PIX2 in that it has a transistor M8 and a capacitor C3. In Figure 14C, elements common to both PIX2 and PIX3 are given the same reference numerals.

[0187] The photodetector PD1 has its cathode connected to wiring V1 and its anode connected to either the source or drain of transistor M4. Transistor M4 has its gate connected to wiring G3 and its other source or drain connected to one electrode of capacitor C3 and one source or drain of transistor M5. Transistor M5 has its gate connected to wiring G4 and its other source or drain connected to wiring V3. The other electrode of capacitor C3 is connected to either the source or drain of transistor M8, one electrode of capacitor C2, and the gate of transistor M6. Transistor M8 has either its source or drain connected to wiring V5 and its gate connected to wiring G6. Transistor M6 has either its source or drain connected to wiring V4 and its other source or drain connected to either the source or drain of transistor M7. Transistor M7 has its gate connected to wiring G5 and its other source or drain connected to wiring OUT.

[0188] Here, node FD1 is defined as the point (wiring, electrode, etc.) connecting the other source or drain of transistor M4, one electrode of capacitor C3, and one source or drain of transistor M5. Also, node FD2 is defined as the point (wiring, electrode, etc.) connecting the other electrode of capacitor C3, one source or drain of transistor M8, one electrode of capacitor C2, and the gate of transistor M6.

[0189] A constant potential is supplied to wirings V1, V3, V4, and V5. When the photodetector PD1 is driven with reverse bias, a potential lower than that of wiring V1 is supplied to wiring V3. Transistor M5 is controlled by a signal supplied to wiring G5 and has the function of resetting node FD1 to the potential supplied to wiring V3. Transistor M8 is controlled by a signal supplied to wiring G6 and has the function of resetting node FD2 to the potential supplied to wiring V5. Transistor M4 is controlled by a signal supplied to wiring G3 and has the function of controlling the timing at which the potential of node FD1 changes according to the current flowing through the photodetector PD1. Transistor M6 functions as an amplifying transistor that outputs according to the potential of node FD2. Transistor M7 is controlled by a signal supplied to wiring G6 and functions as a selection transistor for reading out the output according to the potential of the above nodes with an external circuit connected to wiring OUT.

[0190] PIX3 has nodes FD1 and FD2, which can store electric charge, and these are connected via capacitor C3. Furthermore, reset transistors (transistors M4 and M8) are connected to nodes FD1 and FD2, allowing them to be reset independently. Therefore, the initial state can be stored in node FD2, and the difference between this state and the imaging data stored in node FD1 can be output.

[0191] For example, in the initial state (first imaging), the imaging operation is performed with node FD2 in a reset state, and by making node FD2 floating, the potential of the initial state can be stored.

[0192] Next, only the potential of node FD1 is reset, and the second imaging operation is performed. Since the potential of node FD2 follows the potential change of node FD1 due to the capacitive coupling of capacitor C3, if the potential of node FD1 is the same as the initial state in the second and subsequent imaging operations, the potential of node FD2 will not change, and a difference of 0 (no change) can be read out. Also, if the potential of node FD1 is different from the initial state, the potential of node FD2 will change by the difference from the initial state, and a change can be read out.

[0193] In other words, by using PIX3 as the sub-pixel 23 in one aspect of the present invention, it is possible to read out whether or not there is a change in the eye and its vicinity.

[0194] It is preferable to use transistors having an oxide semiconductor in the channel formation region (hereinafter referred to as OS transistors) for transistors M1 to M8 in the pixel circuits PIX1, PIX2, and PIX3. By using an oxide semiconductor with a large band gap in the semiconductor layer of the transistor, the off-current of the OS transistor can be reduced. The band gap of the oxide semiconductor is preferably 2 eV or more, and more preferably 2.5 eV or more.

[0195] The crystallinity of the semiconductor material used in the semiconductor layer of the transistor is not particularly limited; amorphous semiconductors, single-crystal semiconductors, or semiconductors with crystalline properties other than single crystals (microcrystalline semiconductors, polycrystalline semiconductors, or semiconductors having a crystalline region in part) can all be used. Using a single-crystal semiconductor or a semiconductor with crystalline properties is preferable because it can suppress the degradation of transistor characteristics.

[0196] The semiconductor layer provided in the OS transistor preferably contains indium. Alternatively, it is preferable to have indium, M (where M is one or more 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), and zinc. In particular, it is preferable that M is one or more selected from aluminum, gallium, yttrium, and tin.

[0197] For example, it is preferable to use an indium-containing oxide (InOx) as the semiconductor layer of the OS transistor. Alternatively, it is preferable to use an oxide containing indium and gallium (also written as IGO). Alternatively, it is preferable to use an oxide containing indium, gallium, and zinc (also written as IGZO). Alternatively, it is preferable to use an oxide containing indium, tin, and zinc. Alternatively, it is preferable to use an oxide containing indium, gallium, tin, and zinc.

[0198] Furthermore, the oxide semiconductor used for the semiconductor layer of the OS transistor is preferably formed using the sputtering method or the ALD method. When forming the oxide semiconductor using the sputtering method, productivity can be increased and the film density can be increased. When forming the oxide semiconductor using the ALD method, the coverage of the film can be improved.

[0199] OS transistors, which have a wider bandgap and lower carrier concentration than silicon transistors, can achieve extremely low off-currents. Therefore, this low off-current allows the charge stored in a capacitor connected in series with the transistor to be retained for extended periods.

[0200] Therefore, it is preferable to use transistors made of oxide semiconductors, particularly transistors M1, M4, M5, and M8, which have one or both of their sources or drains connected to capacitors C1, C2, or C3.

[0201] Furthermore, the manufacturing cost of other transistors can also be reduced by using transistors that utilize oxide semiconductors in a similar manner.

[0202] Furthermore, transistors M1 to M8 can also be transistors in which silicon is applied as the semiconductor in which the channel is formed. In particular, using highly crystalline silicon such as single-crystal silicon or polycrystalline silicon is preferable because it can achieve high field-effect mobility, enabling faster operation.

[0203] Furthermore, it is also possible to use a configuration in which one or more of the transistors M1 to M8 are made of oxide semiconductors, and the others are made of silicon.

[0204] Although Figures 14A to 14C illustrate an example using an n-channel transistor, a p-channel transistor can also be used.

[0205] Figure 15A shows an example of a goggle-type device, which is an electronic device according to one aspect of the present invention. Here, the combination of the display panel 20 and the reflective / refractive optical system 30 is shown as a display unit 70 with a dashed line. The display unit 70 corresponds to the configuration shown in Figures 2A, 2B, 7A, 7B, or 8A, 8B.

[0206] The user can view the image displayed on the display panel 20 by bringing their eyes close to the vicinity of the reflective / refracting optical system 30 located on the display surface side of the display panel 20. Because the user views the image with a widened field of view provided by the reflective / refracting optical system 30, they can experience a sense of immersion and presence.

[0207] Two sets of display units 70 are incorporated into the housing 71. One display unit 70 is for the right eye, and the other display unit 70 is for the left eye. By displaying images corresponding to the parallax in each display unit 70, the user can perceive a sense of depth in the images.

[0208] Figure 15B shows an example of a spectacle-type device having the configuration shown in Figure 1. Here, the combination of the display panel 20 and the reflective / refractive optical system 60 is shown as a display unit 92, indicated by a dashed line. The spectacle-type device has two sets of display units 92 housed in the housing 90. The display unit 92 corresponds to the configuration shown in Figures 10A to 10C.

[0209] The front of the housing 90 has a light-transmitting section 96, through which external light is taken into the display unit 92. The user can view the display unit 92 by superimposing the light from the display device onto the external light. The display device can display virtual information. The user can view the virtual information superimposed onto the display, and experience augmented reality by superimposing virtual information onto reality.

[0210] Input and output terminals can also be provided on one or both of the housing 71 and holder 75 shown in Figure 15A, and on one or both of the housing 90 and band 91 shown in Figure 15B. The input terminals can be connected to cables that supply video signals from video output devices, power for charging batteries, etc. The output terminals can function, for example, as audio output terminals, allowing connection of earphones, headphones, etc. However, if the system is configured to output audio data via wireless communication, or if audio is output from an external video output device, the audio output terminals may be omitted.

[0211] Furthermore, a wireless communication module and a storage module can be provided inside one or both of the housing 71 and the holder 75 shown in Figure 15A, and inside one or both of the housing 90 or the band 91 shown in Figure 15B. Wireless communication is performed by the wireless communication module, and content to be viewed can be downloaded and stored in the storage module. This allows the user to view the downloaded content offline.

[0212] Furthermore, the light source 80 and light receiving element of the display panel 20 can function as a gaze detection sensor. The gaze detection sensor uses the light emitted from the light source 80 to detect the position of the gaze by reading the changes in reflected light caused by the movement of the pupil, iris, and white of the eye. For example, it can detect changes in reflectivity caused by actions such as shifting the pupil to one side or up or down, and assign this information to the operation of electronic devices.

[0213] For example, operations such as power on, power off, sleep, volume adjustment, channel change, menu display, selection, confirmation, and back, as well as video playback, stop, pause, fast forward, and rewind, can be assigned to the eyelid opening and closing movements and eyeball movements described above. Furthermore, detected gaze information can also be used for foveal rendering.

[0214] Furthermore, the system can detect the user's fatigue level from dynamic changes in blinking and display an alert. Since blinking is strongly related to eye fatigue, the fatigue level can be estimated by detecting the number of blinks, intervals, and eyelid opening and closing speed within a unit of time.

[0215] If blinking behavior that suggests increasing fatigue is detected, the electronic device can take actions such as displaying a message or sound prompting a break, lowering the display brightness, or lowering the display color temperature to address the user's fatigue.

[0216] Furthermore, if a message or audio prompting a break is displayed, the user may feel uncomfortable if their work, entertainment, or immersion is interrupted against their will. Therefore, when prompting a break, it is preferable to activate equipment that emits sound, vibration, or odor to guide the user to consciously want to take a break.

[0217] While the above example illustrates detecting fatigue through blinking, fatigue or illness can also be detected by obtaining other information. For example, by comparing the amount of reflected light on the surface of the eyeball with that of a normal eye, changes in the tear film can be detected to suppress dry eye or address dry eye symptoms. Additionally, the degree of eye opening (eyelid opening) can be detected by the amount of reflected light and compared with that of a normal eye to estimate the degree of fatigue.

[0218] Furthermore, conscious eyelid opening and closing can be used to perform input actions on electronic devices. For example, actions such as blinking with only one eye, blinking a predetermined number of times within a certain period of time, or closing the eyelids for a certain period of time can be assigned to operate electronic devices.

[0219] (Embodiment 2) This embodiment describes an example of the configuration of a display panel that can be used as a display device according to one aspect of the present invention.

[0220] In the display unit of a display device according to one embodiment of the present invention, it is preferable to use an MML (metal maskless) structure in which the light-emitting layer is separated and formed using a lithography process, rather than using an FMM (fine metal mask) for the light-emitting element. An MML structure light-emitting element can have a higher aperture ratio than a light-emitting element made using an FMM, enabling light emission at high brightness or low power consumption. Furthermore, the light extraction efficiency can be further improved by combining an MML structure light-emitting element with a convex lens.

[0221] [Display Panel 200A] The display panel 200A shown in Figure 16 has a substrate 301, a light-emitting element 110R, a light-receiving element 110PD, capacitors 240a and 240b, and transistors 310a and 310b. The light-emitting element 110R and the light-receiving element 110PD correspond to the light-emitting element of the sub-pixel 22R and the light-receiving element of the sub-pixel 23 shown in Figures 11C to 11E, respectively. The light-emitting element 110R, transistor 310a, and capacitor 240a correspond to, for example, the light-emitting element EL1, transistor M1, and capacitor C1 shown in Figure 14A, respectively. The light-receiving element 110PD, transistor 310b, and capacitor 240b correspond to, for example, the light-receiving element PD1, transistor M4, and capacitor C2 shown in Figure 14B, respectively.

[0222] The transistor 310 (transistors 310a, 310b) is a transistor having a channel formation region in the substrate 301. As the substrate 301, a semiconductor substrate such as a single-crystal silicon substrate can be used. The transistor 310 has 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 of the substrate 301 doped with impurities and functions as either a source or a drain. The insulating layer 314 is provided covering the side surface of the conductive layer 311.

[0223] Furthermore, an element isolation layer 315 is provided between two adjacent transistors so as to be embedded in the substrate 301.

[0224] Furthermore, an insulating layer 261 is provided to cover the transistor 310, and a capacitance 240 is provided on the insulating layer 261.

[0225] Capacitors 240 (capacitors 240a, 240b) have a conductive layer 241 (conductive layers 241a, 241b), a conductive layer 245 (conductive layers 245a, 245b), and an insulating layer 243 located between them. Conductive layer 241 functions as one electrode of capacitor 240, conductive layer 245 functions as the other electrode of capacitor 240, and insulating layer 243 functions as the dielectric of capacitor 240.

[0226] The conductive layer 241 of capacitance 240 is provided on the insulating layer 261 and embedded in the insulating layer 254. The conductive layer 241 is connected to either the source or drain of transistor 310a or 310b by a plug 271 embedded in the insulating layer 261. The insulating layer 243 is provided covering the conductive layer 241. The conductive layer 245 is provided in the region that overlaps with the conductive layer 241 via the insulating layer 243.

[0227] An insulating layer 255a is provided covering the capacitance 240, an insulating layer 255b is provided on top of the insulating layer 255a, and an insulating layer 255c is provided on top of the insulating layer 255b.

[0228] Insulating layers 255a, 255b, and 255c can each preferably be made of inorganic insulating films. For example, it is preferable to use silicon oxide films for insulating layers 255a and 255c, and silicon nitride films for insulating layer 255b. This allows insulating layer 255b to function as an etching protective film. In this embodiment, an example is shown in which a part of insulating layer 255c is etched and a recess is formed, but there are also cases in which no recess is provided in insulating layer 255c.

[0229] A light-emitting element 110R and a light-receiving element 110PD are provided on the insulating layer 255c.

[0230] As the light-emitting element 110R, it is preferable to use, for example, an OLED (Organic Light Emitting Diode) or a QLED (Quantum-dot Light Emitting Diode). As the light-emitting material of the EL element, not only organic compounds but also inorganic compounds (such as quantum dot materials) can be used.

[0231] The light-emitting element 110R includes a pixel electrode 111R, an organic layer 112R, a common layer 114, and a common electrode 113.

[0232] The pixel electrode 111R of the light-emitting element 110R is connected to either the source or drain of the transistor 310a by plugs 256a embedded in insulating layers 255a, 255b, and 255c, a conductive layer 241a embedded in insulating layer 254, and plugs 271a embedded in insulating layer 261.

[0233] The organic layer 112R of the light-emitting element 110R contains at least a light-emitting organic compound that emits red light. The organic layer 112R can also be called an EL layer and has a layer (light-emitting layer) containing at least a light-emitting substance.

[0234] The organic layer 112R and the common layer 114 can each independently have one or more of the following: an electron injection layer, an electron transport layer, a hole injection layer, and a hole transport layer. For example, the organic layer 112R can have a stacked structure of a hole injection layer, a hole transport layer, an emissive layer, and an electron transport layer from the pixel electrode 111R side, and the common layer 114 can have an electron injection layer.

[0235] The common electrode 113 and the common layer 114 are provided as a continuous layer common to the light-emitting element. A conductive film that is transparent to visible light is used on either the pixel electrode or the common electrode 113, and a conductive film that is reflective is used on the other. By making the pixel electrode transparent and the common electrode 113 reflective, a bottom-emission type display device can be made, and conversely, by making the pixel electrode reflective and the common electrode 113 transparent, a top-emission type display device can be made. Furthermore, by making both the pixel electrode and the common electrode 113 transparent, a dual-emission type display device can also be made.

[0236] A protective layer 121 is provided on the common electrode 113, covering the light-emitting element 110R. The protective layer 121 has the function of preventing impurities such as water from diffusing to the light-emitting element from above.

[0237] An insulating layer 124, an insulating layer 125, and a resin layer 126 are provided between adjacent light-emitting elements and light-receiving elements, or between two light-emitting elements.

[0238] The resin layer 126 has a smooth, convex upper surface shape, and the common layer 114 and common electrode 113 are provided covering the upper surface of the resin layer 126.

[0239] The resin layer 126 functions as a planarizing film that fills the step gaps located between adjacent light-emitting elements and light-receiving elements, or between two light-emitting elements. By providing the resin layer 126, it is possible to prevent the common electrode 113 from being separated by the step gap at the edge of the organic layer 112 (also called step breakage), and to prevent the common electrode on the organic layer 112 from becoming insulated.

[0240] Furthermore, the resin layer 126 insulates the organic layers of adjacent light-emitting elements 110 from each other. This reduces the leakage current between adjacent light-emitting elements via the organic layer, thereby suppressing unwanted light emission due to crosstalk.

[0241] As the resin layer 126, an insulating layer having an organic material can be suitably used. For example, as the resin layer 126, acrylic resin, polyimide resin, epoxy resin, imide resin, polyamide resin, polyimidoamide resin, silicone resin, siloxane resin, benzocyclobutene resin, phenol resin, and precursors of these resins can be used. Alternatively, as the resin layer 126, organic materials such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin can also be used.

[0242] The insulating layer 125 is located between the resin layer 126 and the organic layer 112R and functions as a protective film to prevent the resin layer 126 from coming into contact with the organic layer 112.

[0243] The insulating layer 125 can be an insulating layer having an inorganic material. For example, inorganic insulating films such as oxide insulating films, nitride insulating films, oxidative nitride insulating films, and nitride oxide insulating films can be used for the insulating layer 125. The insulating layer 125 is not limited to a single-layer structure, but can also be a multilayer structure. Examples of oxide insulating films include silicon oxide film, aluminum oxide film, magnesium oxide film, indium gallium zinc oxide film, gallium oxide film, germanium oxide film, yttrium oxide film, zirconium oxide film, lanthanum oxide film, neodymium oxide film, hafnium oxide film, and tantalum oxide film. Examples of nitride insulating films include silicon nitride film and aluminum nitride film. Examples of oxidative nitride insulating films include silicon oxidative nitride film and aluminum oxidative nitride film. Examples of nitride oxide insulating films include silicon nitride oxide film and aluminum nitride oxide film. In particular, by applying an aluminum oxide film, a metal oxide film such as a hafnium oxide film, or an inorganic insulating film such as a silicon nitride film or a silicon oxide film, formed by the ALD method, an insulating layer 125 can be formed that has fewer pinholes and excellent function in protecting the EL layer.

[0244] In this specification, the term "oxide-nitride" refers to a material in which the oxygen content is greater than the nitrogen content, and the term "nitride oxide" refers to a material in which the nitrogen content is greater than the oxygen content. For example, when "silicon oxynitride" is written, it refers to a material in which the oxygen content is greater than the nitrogen content, and when "silicon nitride oxide" is written, it refers to a material in which the nitrogen content is greater than the oxygen content.

[0245] The insulating layer 124 is formed when a portion of the protective layer (also called a mask layer or sacrificial layer) used to protect the organic layer 112R remains after etching the organic layer 112R. The insulating layer 124 can be made from the same material that can be used for the insulating layer 125. In particular, it is preferable to use the same material for both the insulating layer 124 and the insulating layer 125, as this allows for the use of common processing equipment and the like.

[0246] The protective layer 121 can be, for example, a single-layer structure or a multi-layer structure including at least an inorganic insulating film. Examples of inorganic insulating films include oxide films or nitride films such as silicon oxide film, silicon oxide nitride film, silicon oxide nitride film, silicon nitride film, aluminum oxide film, aluminum oxide nitride film, and hafnium oxide film. Alternatively, semiconductor materials or conductive materials such as indium gallium oxide, indium zinc oxide, indium tin oxide, and indium gallium zinc oxide can be used as the protective layer 121.

[0247] Furthermore, an insulating layer 103 is provided on the protective layer 121. For example, an organic material that can be used for the resin layer 126 can be used as the insulating layer 103. By forming the insulating layer 103, the influence of uneven shapes caused by the underlying structure can be reduced, making it easier to form structures such as lens arrays.

[0248] A lens 102R, which is a plano-convex lens, is provided on the insulating layer 103 so as to overlap with the light-emitting element 110R. Furthermore, an insulating layer 104 is provided on the lens 102R.

[0249] The lens 102R is positioned above the light-emitting element 110R (in the direction from which light is emitted). Since the light emitted by the light-emitting element 110 has a certain degree of spread, any light that is not extracted to the outside of the display device is lost. Therefore, it is preferable for the display device to have high front brightness. Because the lens 102R has a convex lens shape, it can be made to focus the light. That is, it can suppress the divergence of light emitted by the light-emitting element, thereby increasing the light extraction efficiency of the display device.

[0250] Furthermore, to increase the front brightness of the display panel, it is also effective to use light-emitting elements with higher luminous efficiency. In principle, with tandem organic EL elements, the brightness increases with the number of stacked stages for the same current density, and a two-stage tandem organic EL element can achieve twice the brightness compared to a single-type light-emitting element.

[0251] Furthermore, since the lifespan of an organic EL element depends on the current density, even if the brightness of a tandem organic EL element is doubled, its lifespan will be equivalent to that of a single organic EL element if the current density remains the same. In other words, tandem organic EL elements can be considered an effective technology for increasing the brightness and reliability of organic EL elements.

[0252] A pn-type or PIN-type photodiode can be used as the light-receiving element 110PD. In the light-receiving element 110PD, the amount of charge generated from the light-receiving element 110PD is determined based on the amount of incident light.

[0253] The light-receiving element 110PD can detect infrared light. By using infrared light, which has low visual sensitivity, the impact on the visibility of the display can be suppressed.

[0254] As the light-receiving element 110PD, it is preferable to use an organic photodiode having a layer containing an organic compound. Organic photodiodes can be easily made thinner, lighter, and larger in area, and because they offer a high degree of freedom in shape and design, they can be applied to various display devices.

[0255] In one aspect of the present invention, an organic EL element is used as the light-emitting element 110, and an organic photodiode is used as the light-receiving element 110PD. The organic EL element and the organic photodiode can be formed on the same substrate. Therefore, an organic photodiode can be incorporated into a display device using an organic EL element.

[0256] The same manufacturing method as for the light-emitting element 110R can be applied to the light-receiving element 110PD. The island-shaped active layer (also called the photoelectric conversion layer) of the light-receiving element 110PD is not formed using a fine metal mask, but rather by processing after depositing a film that will become the active layer on one surface, so that the island-shaped active layer can be formed with a uniform thickness. In addition, by providing a mask layer on the active layer, the damage that the active layer receives during the manufacturing process of the display device can be reduced, and the reliability of the light-receiving element 110PD can be improved.

[0257] The light-receiving element 110PD has a pixel electrode 111PD, an organic layer 112PD, a common layer 114, and a common electrode 113.

[0258] The pixel electrode 111PD of the light-receiving element 110PD is connected to either the source or drain of the transistor 310b by a plug 256b embedded in the insulating layer 255a, insulating layer 255b, and insulating layer 255c, a conductive layer 241c embedded in the insulating layer 254, and a plug 271b embedded in the insulating layer 261.

[0259] The organic layer 112PD includes at least an active layer and preferably has a plurality of functional layers. For example, the functional layers include carrier transport layers (hole transport layers and electron transport layers) and carrier block layers (hole block layers and electron block layers). It is also preferable to have one or more layers on the active layer. By having other layers between the active layer and the mask layer, it is possible to suppress the exposure of the active layer to the outermost surface during the manufacturing process of the display device and reduce the damage the active layer receives. This can improve the reliability of the photodetector 110PD. Therefore, it is preferable that the organic layer 112PD has an active layer and a carrier block layer (hole block layer or electron block layer) or a carrier transport layer (electron transport layer or hole transport layer) on the active layer.

[0260] The organic layer 112PD is provided on the light-receiving element 110PD but not on the light-emitting element 110R. However, the functional layers other than the active layer included in the organic layer 112PD may have the same material as the functional layers other than the light-emitting layer included in the light-emitting element 110R. In addition, the common layer 114 and the common electrode 113 are a continuous layer shared by the organic layer 112PD and the light-emitting element 110R.

[0261] Here, layers common to the light-receiving element 110PD and the light-emitting element 110R may have different functions in the light-emitting element 110R and in the light-receiving element 110PD. In this specification, components may be referred to based on their function in the light-emitting element 110R. For example, a hole injection layer functions as a hole injection layer in the light-emitting element 110R and as a hole transport layer in the light-receiving element 110PD. Similarly, an electron injection layer functions as an electron injection layer in the light-emitting element 110R and as an electron transport layer in the light-receiving element 110PD. Furthermore, layers common to the light-receiving element 110PD and the light-emitting element 110R may have the same function in the light-emitting element 110R and in the light-receiving element 110PD. For example, a hole transport layer functions as a hole transport layer in both the light-emitting element 110R and the light-receiving element 110PD, and an electron transport layer functions as an electron transport layer in both the light-emitting element 110R and the light-receiving element 110PD.

[0262] An insulating layer 103 is provided on the common electrode 113, similar to the insulating layer 110R. A plano-convex lens 102PD is provided on the insulating layer 103 so as to overlap with the light-receiving element 110PD. A substrate 163 is provided on the lens 102PD via an insulating layer 104.

[0263] Since the lens 102PD has a convex shape, it can be made to focus light. Therefore, more light can be incident on the photodetector 110PD, thereby increasing the detection sensitivity of the photodetector 110PD.

[0264] [Display Panel 200B] The display panel 200B shown in Figure 17 has a configuration in which transistors 310A and 310B, each with a channel formed on a semiconductor substrate, are stacked. In the following description of the display panel, parts that are the same as those described earlier may be omitted.

[0265] The display panel 200B has a configuration in which a substrate 301B on which a transistor 310B, a capacitor 240, and a light-emitting device are provided, and a substrate 301A on which a transistor 310A is provided are bonded together.

[0266] Here, an insulating layer 345 is provided on the lower surface of substrate 301B, and an insulating layer 346 is provided on top of the insulating layer 261 provided on substrate 301A. Insulating layers 345 and 346 are insulating layers that function as protective layers and can suppress the diffusion of impurities into substrates 301B and 301A. As insulating layers 345 and 346, inorganic insulating films that can be used for the protective layer 121 can be used.

[0267] A plug 343 is provided on the substrate 301B, which penetrates both the substrate 301B and the insulating layer 345. Here, it is preferable to provide an insulating layer 344 that covers the side surface of the plug 343 and functions as a protective layer.

[0268] Furthermore, the substrate 301B has a conductive layer 342 provided below the insulating layer 345. The conductive layer 342 is embedded in the insulating layer 335, and the undersides of the conductive layer 342 and the insulating layer 335 are flattened. The conductive layer 342 is also connected to the plug 343.

[0269] On the other hand, the substrate 301A has a conductive layer 341 on top of an insulating layer 346. The conductive layer 341 is embedded in the insulating layer 336, and the upper surfaces of the conductive layer 341 and the insulating layer 336 are flattened.

[0270] It is preferable to use the same conductive material for conductive layer 341 and conductive layer 342. For example, a metal film containing an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W, or a metal nitride film (titanium nitride film, molybdenum nitride film, tungsten nitride film) composed of the above elements can be used. In particular, it is preferable to use copper for conductive layer 341 and conductive layer 342. This makes it possible to apply Cu-Cu (copper-copper) direct bonding technology (a technology that achieves electrical conductivity by connecting Cu (copper) pads to each other).

[0271] [Display Panel 200C] The display panel 200C shown in Figure 18 has a configuration in which conductive layer 341 and conductive layer 342 are joined via bumps 347.

[0272] As shown in Figure 18, by providing a bump 347 between the conductive layer 341 and the conductive layer 342, the conductive layer 341 and the conductive layer 342 can be electrically connected. The bump 347 can be formed using a conductive material including, for example, gold (Au), nickel (Ni), indium (In), or tin (Sn). Alternatively, solder may be used as the bump 347. An adhesive layer 348 can also be provided between the insulating layer 345 and the insulating layer 346. Furthermore, when the bump 347 is provided, the insulating layer 335 and the insulating layer 336 may be omitted.

[0273] [Display Panel 200D] The display panel 200D shown in Figure 19 differs from the display panel 200A mainly in its transistor configuration.

[0274] Transistor 320 (transistors 320a, 320b) is an OS transistor in which a metal oxide (also called an oxide semiconductor) is applied to the semiconductor layer where the channel is formed.

[0275] The transistor 320 has 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.

[0276] An insulating layer 332 is provided on 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 detaching from the semiconductor layer 321 to the insulating layer 332. As the insulating layer 332, for example, a film that is less susceptible to hydrogen or oxygen diffusion than a silicon oxide film can be used, such as an aluminum oxide film, a hafnium oxide film, or a silicon nitride film.

[0277] A conductive layer 327 is provided on an insulating layer 332, and an insulating layer 326 is provided covering the conductive layer 327. The conductive layer 327 functions as the first gate electrode of the transistor 320, and a part of the insulating layer 326 functions as the first gate insulating layer. It is preferable to use an oxide insulating film such as a silicon oxide film for at least the portion of the insulating layer 326 that is in contact with the semiconductor layer 321. It is preferable that the upper surface of the insulating layer 326 is flattened.

[0278] The semiconductor layer 321 is provided on the insulating layer 326. Preferably, the semiconductor layer 321 has a metal oxide (also called an oxide semiconductor) film that exhibits semiconductor properties. A pair of conductive layers 325 are provided in contact with the semiconductor layer 321 and function as a source electrode and a drain electrode.

[0279] An insulating layer 328 is provided covering the top and side surfaces of a pair of conductive layers 325, as well as the side surfaces of the semiconductor layer 321, and an insulating layer 264 is provided on the insulating layer 328. The insulating layer 328 functions as a barrier layer to prevent impurities such as water or hydrogen from diffusing into the semiconductor layer 321 from the insulating layer 264, etc., and to prevent oxygen from detaching from the semiconductor layer 321. An insulating film similar to that of the insulating layer 332 can be used as the insulating layer 328.

[0280] The insulating layer 328 and the insulating layer 264 are provided with openings that reach the semiconductor layer 321. An insulating layer 323 in contact with the upper surface of the semiconductor layer 321 and a conductive layer 324 are embedded inside these openings. The conductive layer 324 functions as a second gate electrode, and the insulating layer 323 functions as a second gate insulating layer.

[0281] The upper surfaces of the conductive layer 324, the insulating layer 323, and the insulating layer 264 are flattened so that their heights are the same or approximately the same, and the insulating layer 329 and insulating layer 265 are provided covering them.

[0282] Insulating layers 264 and 265 function as interlayer insulating layers. Insulating layer 329 functions as a barrier layer to prevent impurities such as water or hydrogen from diffusing into the transistor 320 from the insulating layer 265, etc. As insulating layer 329, an insulating film similar to that used for insulating layers 328 and 332 can be used.

[0283] A plug 274, which connects to one of the pair of conductive layers 325, is provided so as to be embedded in the insulating layer 265, insulating layer 329, and insulating layer 264. Here, it is preferable that the plug 274 has a conductive layer 274a that covers the sides of the openings of the insulating layer 265, insulating layer 329, insulating layer 264, and insulating layer 328, and a part of the upper surface of the conductive layer 325, and a conductive layer 274b that is in contact with the upper surface of the conductive layer 274a. In this case, it is preferable to use a conductive material that does not easily allow hydrogen and oxygen to diffuse as the conductive layer 274a.

[0284] The structure of the transistors in the display panel of this embodiment is not particularly limited. For example, planar transistors, staggered transistors, inverse staggered transistors, etc., can be used. In addition, either top-gate or bottom-gate transistor structures can be used. Alternatively, gates can be provided above and below the semiconductor layer in which the channel is formed.

[0285] The transistor 320 employs a configuration in which a semiconductor layer on which a channel is formed is sandwiched between two gates. The transistor can be driven by connecting the two gates and supplying them with the same signal. Alternatively, the threshold voltage of the transistor can be controlled by applying a potential to control the threshold voltage to one of the two gates and a potential to drive the transistor to the other.

[0286] OS transistors have extremely high field-effect mobility compared to transistors using amorphous silicon. Furthermore, OS transistors exhibit remarkably low source-drain leakage current (also called off-current) in the off state, allowing them to retain charge stored in a capacitor connected in series with the transistor for extended periods. Additionally, the application of OS transistors can reduce the power consumption of display panels.

[0287] Furthermore, to increase the luminescence brightness of the light-emitting device included in the pixel circuit, it is necessary to increase the amount of current flowing through the light-emitting device. To achieve this, it is necessary to increase the source-drain voltage of the drive transistor included in the pixel circuit. Compared to Si transistors, OS transistors have a higher breakdown voltage between the source and drain, so a higher voltage can be applied to the source-drain of an OS transistor. Therefore, by using an OS transistor as the drive transistor included in the pixel circuit, the amount of current flowing through the light-emitting device can be increased, thereby increasing the luminescence brightness of the light-emitting device.

[0288] Furthermore, when the transistor operates in the saturation region, OS transistors exhibit a smaller change in source-drain current in response to changes in gate-source voltage compared to Si transistors. Therefore, by using OS transistors as driving transistors in the pixel circuit, the current flowing between the source and drain can be precisely controlled by changes in gate-source voltage, thereby allowing control of the current flowing to the light-emitting device. This allows for an increase in the number of grayscale levels in the pixel circuit.

[0289] Furthermore, in terms of the saturation characteristics of the current flowing when a transistor operates in the saturation region, OS transistors can supply a more stable current (saturation current) than Si transistors, even when the source-drain voltage gradually increases. Therefore, by using OS transistors as driving transistors, a stable current can be supplied to the light-emitting device even if there are variations in the current-voltage characteristics of the EL device. In other words, when operating in the saturation region, the source-drain current remains almost unchanged even when the source-drain voltage is increased, thus stabilizing the luminescence brightness of the light-emitting device.

[0290] [Display Panel 200E] The display panel 200E shown in Figure 20 has a configuration in which a transistor 310 with a channel formed on a substrate 301 and transistors 320 (transistors 320a, 320b) containing a metal oxide in the semiconductor layer where the channel is formed are stacked.

[0291] An insulating layer 261 is provided covering the transistor 310, and a conductive layer 251 is provided on the insulating layer 261. An insulating layer 262 is provided covering the conductive layer 251, and a conductive layer 252 is provided on the insulating layer 262. The conductive layer 251 and the conductive layer 252 each function as wiring. An insulating layer 263 and an insulating layer 332 are provided covering the conductive layer 252, and a transistor 320 is provided on the insulating layer 332.

[0292] Transistor 320 can be used as a transistor constituting a pixel circuit. Transistor 310 can also be used as a transistor constituting a pixel circuit, or as a transistor constituting a drive circuit (gate line drive circuit, source line drive circuit) for driving the pixel circuit. Transistor 310 can also be used as a transistor constituting various circuits such as arithmetic circuits or memory circuits.

[0293] This configuration allows for the formation of not only pixel circuits but also drive circuits directly beneath the light-emitting and light-receiving elements, making it possible to miniaturize the display panel compared to cases where the drive circuits are located around the display area.

[0294] [Display Panel 200F] The display panel 200F shown in Figure 21 is a configuration in which the transistor 320 of the display panel 200E shown in Figure 20 is replaced with a transistor 330 (vertical transistor: transistors 330a, 330b). Note that the configuration of replacing transistor 320 with transistor 330 can also be applied to the display panel 200D shown in Figure 19.

[0295] Figure 22A shows a cross-sectional view of transistor 330 in the XZ plane. Figure 22B shows a cross-sectional view in the XY plane, including wiring 440.

[0296] The transistor 330 comprises 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 either the source electrode or the drain electrode of the transistor 330. The wiring 440 has a region that functions as either the source electrode or the drain electrode of the transistor 330.

[0297] The wiring 440 and the insulator 480 are provided with openings 490 that penetrate through them and reach the wiring 450. The openings 490 have a columnar shape with an approximately circular upper surface. This configuration allows for miniaturization or high integration of the memory cell. Preferably, the side surface of the opening 490 is perpendicular to the upper surface of the wiring 450.

[0298] At least a portion of the oxide semiconductor 470 is placed in the opening 490. The oxide semiconductor 470 has a region in contact with the upper 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.

[0299] The insulator 430 is positioned such that at least a portion of it covers the opening 490. The conductor 420 is positioned such that at least a portion of it is located in the opening 490. Preferably, the conductor 420 is provided so as to fill the opening 490, and in order to increase the degree of integration, its shape in a top view is preferably roughly circular.

[0300] As shown in Figure 22A, the oxide semiconductor 470 has a region 470i and regions 470na and 470nb that are provided so as to sandwich region 470i.

[0301] Region 470na is the region of the oxide semiconductor 470 that is in contact with the wiring 450. At least a portion of region 470na functions as one of the source region and drain region of the transistor 330. Region 470nb is the region of the oxide semiconductor 470 that is in contact with the wiring 440. At least a portion of region 470nb functions as the other of the source region and drain region of the transistor 330. As shown in Figure 22B, the wiring 440 is in contact with the entire outer periphery of the oxide semiconductor 470. Therefore, the other of the source region and drain region of the transistor 330 can be formed on the entire outer periphery of the portion of the oxide semiconductor 470 that is formed in the same layer as the wiring 440.

[0302] Region 470i is the region in the oxide semiconductor 470 sandwiched between region 470na and region 470nb. At least a portion of region 470i functions as the channel formation region of transistor 330. In other words, the channel formation region of transistor 330 is formed in a portion of the oxide semiconductor 470 located in the region between wiring 450 and wiring 440. Alternatively, the channel formation region of transistor 330 can be said to be located in the region of the oxide semiconductor 470 that is in contact with the insulator 480 or in a region near it.

[0303] The channel length of transistor 330 is the distance between the source region and the drain region. In other words, the channel length of transistor 330 is determined by the thickness of the insulator 480 on the wiring 450. Figure 22A shows the channel length L of transistor 330 with a dashed double arrow. In a cross-sectional view, the channel length L is the distance between the end of the region where the oxide semiconductor 470 and the wiring 450 are in contact and the end of the region where the oxide semiconductor 470 and the wiring 440 are in contact. 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.

[0304] In planar transistors, the channel length is limited by the exposure limit of photolithography, making further miniaturization difficult. 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 330 can be made into an extremely fine structure below 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 makes it possible to increase the on-current of the transistor 330.

[0305] Furthermore, as described above, a channel formation region, a source region, and a drain region can be formed in the aperture 490. This reduces the area occupied by the transistor 330 compared to a planar transistor where the channel formation region, source region, and drain region are separately provided on the XY plane. This allows for an increase in pixel density.

[0306] Thus, a transistor having a channel-forming region along the side surface of the insulator 480 at the opening 490 is also called a vertical transistor.

[0307] Furthermore, in the XY plane including the channel formation region of the oxide semiconductor 470, the oxide semiconductor 470, the insulator 430, and the conductor 420 are arranged concentrically, similar to Figure 22B. Therefore, the side surface of the conductor 420 located at the center faces the side surface of the oxide semiconductor 470 via the insulator 430. In other words, in a top view, the entire perimeter of the oxide semiconductor 470 becomes the channel formation region. In this case, for example, the channel width of the transistor 330 is determined by the length of the outer circumference of the oxide semiconductor 470. That is, the channel width of the transistor 330 can be said to be determined by the size of the maximum width of the opening 490 (the diameter if the opening 490 is circular in a top view). Figures 22A and 22B show the maximum width D of the opening 490 with a double-headed arrow. Figure 22B shows the channel width W of the transistor 330 with a double-headed arrow. By increasing the size of the maximum width D of the opening 490, the channel width per unit area can be increased, and the on-current can be increased.

[0308] When forming the aperture 490 using photolithography, the maximum width D of the aperture 490 is limited by the exposure limit of the photolithography. Furthermore, the maximum width D of the aperture 490 is set by the film thickness of the oxide semiconductor 470, insulator 430, and conductor 420 provided in the aperture 490. The maximum width D of the aperture 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. Note that if the aperture 490 is circular in a top view, the maximum width D of the aperture 490 corresponds to the diameter of the aperture 490, and the channel width W can be calculated as "D × π".

[0309] Furthermore, in a memory device according to one aspect of the present invention, it is preferable that the channel length L of the transistor 330 is at least smaller than the channel width W of the transistor 330. In one aspect of the present invention, the channel length L of the transistor 330 is 0.1 times or more and 0.99 times or less, preferably 0.5 times or more and 0.8 times or less, the channel width W of the transistor 330. By adopting such a configuration, a transistor with good electrical characteristics and high reliability can be realized.

[0310] Furthermore, by forming the opening 490 so that it is roughly circular when viewed from above, the oxide semiconductor 470, the insulator 430, and the conductor 420 are arranged concentrically. As a result, the distance between the conductor 420 and the oxide semiconductor 470 becomes roughly uniform, so that the gate electric field can be applied to the oxide semiconductor 470 roughly uniformly.

[0311] In transistors using oxide semiconductors for the semiconductor layer, the channel formation region preferably has fewer oxygen vacancies or lower concentrations of impurities such as hydrogen, nitrogen, and metallic elements than the source and drain regions. For example, the concentration of aluminum in the channel formation region of an oxide semiconductor is 1 × 10⁻⁶. ２２ atoms / cm ３ The following is preferable: 1 × 10 ２１ atoms / cm ３ The following is more preferable: 1 × 10 ２０ atoms / cm ３ The following is more preferable: 5 × 10 １９ atoms / cm ３ The following is more preferable: 1 × 10 １９ atoms / cm ３ The following is more preferable: 5 × 10 １８ atoms / cm ３ The following is more preferable: 1 × 10 １８ atoms / cm ３ The following are even more preferable.

[0312] Furthermore, hydrogen near the oxygen vacancy can fill the oxygen vacancy, creating a defect (hereinafter referred to as V). Ｏ In the channel-forming region, V may form (sometimes called H) and generate electrons that become carriers. Ｏ It is preferable that H is also reduced. Thus, 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 type i (intrinsic) or substantially type i.

[0313] Furthermore, the source and drain regions of a transistor using an oxide semiconductor for the semiconductor layer have more oxygen vacancies than the channel formation region. ＯThis region has a high concentration of hydrogen (H), or high concentrations of impurities such as hydrogen, nitrogen, and metallic elements, resulting in increased carrier concentration and low resistance. In other words, the source and drain regions of a transistor are n-type regions with higher carrier concentration and lower resistance compared to the channel formation region.

[0314] In Figure 22A and other figures, the opening 490 is provided such that its side surface 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 can also be tapered.

[0315] This embodiment can be implemented in appropriate combination with other embodiments and examples described herein, at least in part.

[0316] (Embodiment 3) This embodiment describes an indium oxide film that can be used in the semiconductor layer of a transistor in a display device according to one aspect of the present invention.

[0317] In this specification, indium oxide having at least a crystalline portion or crystalline region in the film is referred to as crystalline indium oxide (crystal IO) or crystalline indium oxide (crystalline IO). Examples of crystal IO or crystalline IO include single-crystal indium oxide, polycrystalline indium oxide, and microcrystalline indium oxide.

[0318] Indium oxide is a semiconductor material with completely different physical properties from oxide semiconductors such as In-Ga-Zn oxide (hereinafter also referred to as IGZO) and zinc oxide.

[0319] This section describes the carrier concentration dependence of the hole (Hall) mobility of indium oxide, silicon, and IGZO. Figure 23A shows silicon (Si) and indium oxide (InO2). Ｘ Figure 23B is a schematic diagram of the carrier concentration dependence of hole mobility with respect to IGZO.

[0320] First, as indicated by the arrows in Figure 23B, IGZO tends to exhibit higher hole mobility as the carrier concentration increases. On the other hand, as indicated by the arrows in Figure 23A, indium oxide tends to exhibit higher hole mobility as the carrier concentration decreases (see Non-Patent Literature 1). This trend is similar to that of silicon, where the lower the concentration of dopants (impurities) in the material, the less impurity scattering occurs and the higher the hole mobility. In other words, the higher the purity and intrinsic nature of indium oxide, the higher its hole mobility. From these results, it can be said that indium oxide, unlike IGZO, is a material with physical properties similar to silicon. Note that the properties of indium oxide shown in Figure 23A are assumed to be those of a single crystal. Therefore, when indium oxide is not a single crystal (for example, polycrystalline), the properties may differ from those shown in Figure 23A.

[0321] In Figure 23A, the low carrier concentration range R1 exhibits extremely high hole mobility, making it a suitable carrier concentration range for, for example, the channel formation region of a transistor. For example, in the case of indium oxide, the range R1 has a carrier concentration of 1 × 10⁻⁶. １５ cm −３ This range includes, for example, 1 × 10 １４ cm −３ The above is 1 x 10 １８ cm −３ The range is as follows: By sufficiently reducing the carrier concentration, the hole mobility value can be increased to 270 cm⁻¹. ２ It can be expected to be raised to the level of / (V・s).

[0322] Furthermore, in indium oxide, the region where the carrier concentration is in the range R1 may contain elements that lower the carrier concentration. Examples of elements that lower the carrier concentration include magnesium, calcium, zinc, cadmium, and copper. By substituting these elements for indium, the carrier concentration can be lowered. Other elements that lower the carrier concentration include nitrogen, phosphorus, arsenic, and antimony. For example, by substituting nitrogen, phosphorus, arsenic, or antimony for oxygen, the carrier concentration can be lowered.

[0323] On the other hand, the range R2 with high carrier concentration has low electrical resistance and can be said to be a suitable range of carrier concentration for applications such as the source and drain regions of a transistor, or for resistors or transparent conductive films. The range R2 is when the carrier concentration value is 1 × 10⁻⁶. ２０ cm −３ This range includes, for example, 1 × 10 １９ cm −３ The above is 1 x 10 ２２ cm −３ The range is as follows: By making the carrier concentration sufficiently high, the resistivity can be increased to 1 × 10⁻⁶. −４ It is expected that the level can be reduced to below Ω·cm.

[0324] Furthermore, in the indium oxide, the region where the carrier concentration is in the range R2 may contain elements that increase the carrier concentration. For example, it is preferable to include elements common to the source and drain electrodes of the transistor. Examples of elements that increase the carrier concentration include titanium, zirconium, hafnium, tantalum, tungsten, molybdenum, tin, silicon, and boron. In particular, it is more preferable to use elements in which the oxide is conductive or semiconducting.

[0325] In this way, indium oxide uses regions with low carrier concentrations for the transistor's channel formation region and regions with high carrier concentrations for the transistor's source and drain regions. In other words, indium oxide can be said to be an oxide in which valence electron control is possible. In IGZO, however, strain can form in the source and drain regions due to stress on the electrodes in contact with the IGZO, and n-type regions may be formed. On the other hand, unlike IGZO, indium oxide allows for valence electron control, so it does not require the formation of strain in the film as in IGZO. Less strain in the film is expected to improve reliability. For example, by creating regions with carrier concentrations in the range R1 and range R2 shown in Figure 23A within the indium oxide film, a so-called n-i-n junction (a junction between an n-type region, an i-type region, and an n-type region) can be created. Valence electron control in silicon transistors is generally known. On the other hand, valence electron control in indium oxide transistors is a novel technological concept that would not normally be conceived.

[0326] By applying the above technical concept, the indium oxide transistor described herein has two or more, preferably three or more, more preferably four or more, and most preferably five of the following features (1) to (5): (1) High on-current (in other words, high mobility). (2) Low off-current. (3) Normally off is possible. (4) High reliability. (5) High cutoff frequency (fT). For example, the indium oxide transistor described herein has high mobility, low off-current, and is normally off. This transistor is different from a transistor that is high mobility and normally on.

[0327] Next, we will describe indium oxide films applied to transistors. Indium oxide films are preferably crystalline (i.e., they have crystal grains). Examples of films with crystal grains include single-crystal films, polycrystalline films, or amorphous films containing crystal grains (also called microcrystalline films). In particular, polycrystalline films are preferred for indium oxide films, and single-crystal films are more preferred. Single-crystal films do not have crystal grain boundaries. Impurities that inhibit carrier flow (typically insulating impurities, insulating oxides, etc.) tend to segregate at crystal grain boundaries. By using single-crystal films, carrier scattering at crystal grain boundaries can be suppressed, enabling the realization of transistors exhibiting high field-effect mobility. Furthermore, it has the excellent effect of suppressing variations in transistor characteristics caused by these crystal grain boundaries.

[0328] Furthermore, polycrystalline films are preferable because they can reduce carrier scattering and exhibit high field-effect mobility compared to microcrystalline or amorphous films. When using polycrystalline films, it is preferable to use films with the largest possible grain size and few grain boundaries. In a transistor to which a polycrystalline indium oxide film is applied, if there are no grain boundaries in the channel formation region, or if no grain boundaries are observed, the channel formation region is located within the single-crystal region contained in the polycrystalline film, and therefore it can be considered a transistor to which single-crystal indium oxide is applied.

[0329] The crystallinity of indium oxide can be analyzed, for example, by X-ray diffraction (XRD), transmission electron microscopy (TEM), or electron diffraction (ED). Alternatively, a combination of these methods may be used for analysis.

[0330] Furthermore, in this specification, a semiconductor layer in which no grain boundaries are observed in the channel-forming region, a semiconductor layer in which the channel-forming region is contained within a single crystal grain, or a semiconductor layer in which the direction of the crystal axes is the same in at least two regions within the channel-forming region can be called a single crystal film. In addition, a semiconductor layer in which, within a single crystal grain in the channel-forming region, the direction of other crystal axes changes continuously with respect to a certain crystal axis or crystal orientation as the axis of rotation can be called a single crystal film.

[0331] The channel formation region refers to the area within the semiconductor layer that overlaps with (or faces) the gate electrode via the gate insulating layer, and is located between the region in contact with the source electrode and the region in contact with the drain electrode. The current path in the channel formation region is the shortest distance between the source electrode and the drain electrode. Therefore, the crystal grains, grain boundaries, crystal axes, and crystal orientation in the channel formation region can be confirmed by cross-sectional observation including the semiconductor layer, source electrode, and drain electrode.

[0332] The indium oxide film in the channel-forming region is preferable to have a low impurity concentration. Impurities in the indium oxide film in the channel-forming region can act as a scattering source for carriers, and thus can cause a decrease in field-effect mobility. Furthermore, these impurities can also inhibit crystal growth in the indium oxide film. Examples of impurities in the indium oxide film include boron and silicon. The concentration of these impurities in the indium oxide film is preferably 0.1% or less, and more preferably 0.01% (100 ppm) or less. Note that elements such as carbon and hydrogen may be present in the deposition gas or precursor during film formation, and may remain in the indium oxide film in higher concentrations than the impurities mentioned above.

[0333] Furthermore, the indium oxide film in the channel-forming region may contain elements that can become trivalent cations like indium, as long as their crystals maintain a cubic crystal structure (Bixbite type). Examples include Group 13 elements of the periodic table such as gallium and aluminum, and Group 3 elements of the periodic table. Since these elements mainly exist as trivalent cations in the oxide, the carrier concentration of indium oxide can be kept low.

[0334] By using such an indium oxide film in a transistor, the field-effect mobility of the transistor can be increased to 50 cm². ２ / (V·s) or more, preferably 100 cm ２ / (V·s) or more, more preferably 150 cm ２ / (V·s) or more, more preferably 200 cm ２ / (V·s) or more, more preferably 250 cm ２ It can be set to (V・s) or more.

[0335] One of the characteristics of indium oxide films is that they have higher oxygen permeability (diffusivity) compared to IGZO films. As shown in Figure 23C, indium oxide films (InO Ｘ Oxygen (O) diffusing into the indium oxide film passes through the indium oxide film, and oxygen molecules (O) ２ It is released as water molecules (H) by reacting with hydrogen contained in the membrane. ２ It may also be released as O. Furthermore, oxygen deficiencies (V) can form in the membrane. Ｏ If oxygen atoms are present, diffusing oxygen atoms will fill the oxygen deficiency. Indium oxide films allow oxygen to diffuse easily, so they can be said to fill oxygen deficiencies more easily than IGZO films.

[0336] Thus, because indium oxide films are more likely to reduce oxygen vacancies in the film compared to IGZO films, applying such indium oxide films to transistors makes it possible to realize transistors with extremely high reliability.

[0337] Furthermore, as shown in Figure 23C, the indium oxide film diffuses hydrogen. Hydrogen diffusing into the indium oxide film from the outside permeates the film and forms hydrogen molecules (H ２ It is released as ) or, by reacting with oxygen contained in the membrane, it is released as water molecules.

[0338] Transistors using indium oxide films are storage-type transistors that use electrons as majority carriers. Assuming that the carrier relaxation time is constant, the smaller the effective mass of electrons (carriers), the higher the electron mobility. In other words, by using indium oxide, which has a small effective mass of electrons, in a transistor, the on-current or field-effect mobility of the transistor can be increased.

[0339] Table 2 shows single crystal indium oxide (here, In ２ O ３ The effective masses of indium oxide and single-crystal silicon (Si) are shown below. As shown in Table 2, indium oxide is characterized by a small effective electron mass and a large effective hole mass. Furthermore, the effective electron mass of indium oxide is almost independent of the crystal orientation. Therefore, by using crystalline indium oxide in transistors, transistors with high field-effect mobility and high frequency characteristics (also called f-characteristics) can be realized. In addition, because the effective hole mass is large, transistors with extremely low off-currents can be realized. For example, by applying an indium oxide film to a vertical transistor, the off-current per 1 μm of channel width is 1 fA (1 × 10⁻¹⁶) in an environment of 125°C. −１５ A) Less than or equal to, or 1aA (1 × 10 −１８ A) Less than or equal to 1aA (1 × 10) in a room temperature (25°C) environment. −１８ A) Less than or equal to, or 1zA (1 × 10⁻¹⁰ −２１ A) The following is possible. Furthermore, as shown in Table 2, indium oxide has a smaller effective electron mass and a larger effective hole mass than silicon, so it may be possible to realize a transistor with higher field-effect mobility and lower off-current than a Si transistor.

[0340]

[0341] It is preferable to provide a seed layer so as to be in contact with at least a portion of the crystalline indium oxide film. It is preferable to use a material containing crystals with a small difference in lattice constant (also called lattice mismatch) with the indium oxide for the seed layer. This improves the crystallinity of the indium oxide film. A substrate (e.g., a single-crystal substrate) may be used as one of the layers in contact with at least a portion of the crystalline indium oxide film.

[0342] One method for evaluating the degree of lattice mismatch is to use the following lattice mismatch value. The lattice mismatch Δa [%] of the crystals in the formed film (in this case, the indium oxide film) relative to the crystals in the seed layer is given by Δa = ((L １ -L ２ ) / L ２ It is calculated as ) × 100. Here L １ L is the length of the unit cell vector of the crystals in the formed film, or the lattice constant. ２ This is the length of the unit cell vector of the crystal in the seed layer, or the lattice constant.

[0343] The lattice mismatch Δa between the seed layer and the indium oxide film is preferably small in absolute value, and most preferably zero. For example, Δa can be -5% or more and 5% or less, preferably -4% or more and 4% or less, more preferably -3% or more and 3% or less, and even more preferably -2% or more and 2% or less.

[0344] Here, the indium oxide crystal has a cubic structure (bixbite type). For example, yttria-stabilized zirconia (YSZ) crystals can have a cubic structure (fluorite type). The lattice mismatch of the indium oxide crystal with respect to the cubic YSZ crystal is in the range of -2% to 2%, and a single crystal film of indium oxide can be epitaxially grown on a YSZ substrate.

[0345] Furthermore, the crystal structure of the seed layer and the crystal structure of the indium oxide film do not necessarily have to be the same in terms of crystal system or crystal orientation. For example, a film with a hexagonal or trigonal crystal structure can be used beneath an indium oxide film with a cubic crystal structure. For example, by setting the crystal orientation of the surface of the seed layer to

[001] and the crystal orientation of the underside of the indium oxide film to

[111] , the requirements related to crystal orientation necessary for epitaxial growth can be met. Examples of hexagonal or trigonal crystals include wurtzite-type structures and YbFe. ２ O ４ Type structure, Yb ２ Fe ３ O ７ These include type structures and their modified type structures. YbFe ２ O ４ Type structure or Yb ２ Fe ３ O ７ An example of a crystal having a type structure is IGZO.

[0346] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part.

[0347] 14: Pixel array, 15: Circuit, 16: Circuit, 17: Circuit, 18: Circuit, 19: Circuit, 20: Display panel, 21: Pixel, 21a: Pixel, 21b: Pixel, 22: Sub-pixel, 22B: Sub-pixel, 22b: Sub-pixel, 22G: Sub-pixel, 22R: Sub-pixel, 22W: Sub-pixel, 23: Sub-pixel, 25: Region, 26: Region, 27: Region, 30: Reflective / refractive optical system, 31: Linear polarizer, 32: Phase difference plate, 33: Half mirror, 34: Half mirror, 35: Phase difference plate, 36: Reflective polarizer, 37: Half mirror, 38: Reflective polarizer, 39: Reflective polarizer, 40: Eye, 41: Retina, 42: Pupil 51: Lens, 52: Support, 53: Support, 54: Support, 55: Mirror, 56: Support, 57: Optical axis, 58: Lens, 59: Aperture, 59T: Transmitting region, 60: Reflective / refracting optical system, 61: Linear polarizer, 62: Reflective polarizer, 63: Phase difference plate, 64: Half mirror, 65: Half mirror, 66: Phase difference plate, 67: Linear polarizer, 70: Display unit, 71: Housing, 75: Holder, 80: Light source, 81: Linear polarizer, 90: Housing, 91: Band, 92: Display unit, 96: Light-transmitting part, 102PD: Lens, 102R: Lens, 103: Insulating layer, 104: Insulating layer , 110: Light-emitting element, 110PD: Photodetector, 110R: Light-emitting element, 111PD: Pixel electrode, 111R: Pixel electrode, 112: Organic layer, 112PD: Organic layer, 112R: Organic layer, 113: Common electrode, 114: Common layer, 121: Protective layer, 124: Insulating layer, 125: Insulating layer, 126: Resin layer, 163: Substrate, 200A: Display panel, 200B: Display panel, 200C: Display panel, 200D: Display panel, 200E: Display panel, 200F: Display panel, 240: Capacitor, 240a: Capacitor, 240b: Capacitor, 241: Conductive layer, 241a: Conductive layer, 241b: Conductive layer, 241c: conductive layer, 243: insulating layer, 245: conductive layer, 245a: conductive layer, 245b: conductive layer, 251: conductive layer, 252: conductive layer, 254: insulating layer, 255a: insulating layer, 255b: insulating layer, 255c: insulating layer, 256a: plug, 256b: plug, 261: insulating layer, 262: insulating layer, 263: insulating layer, 264: insulating layer, 265: insulating layer, 271: plug, 271a: plug, 271b: plug, 274: plug, 274a: conductive layer, 274b: conductive layer, 301: substrate, 301A: substrate, 301B: substrate, 310: transistor, 310A: transistor,310a: Transistor, 310B: Transistor, 310b: Transistor, 311: Conductive layer, 312: Low resistance region, 313: Insulating layer, 314: Insulating layer, 315: Element isolation layer, 320: Transistor, 320a: Transistor, 320b: 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, 330: Transistor, 330a: Transistor, 330b: Transistor, 331: Substrate, 332: Insulating layer, 335: Insulating layer, 336: Insulating layer, 341: Conductive layer, 342: Conductive layer, 343: Plug, 344: Insulating layer, 345: Insulating layer, 346: Insulating layer, 347: Bump, 348: Adhesive layer, 420: Conductor, 430: Insulator, 440: Wiring, 450: Wiring, 470: Oxide semiconductor, 470i: Region, 470na: Region, 470nb: Region, 480: Insulator, 490: Aperture,

Claims

1. An electronic device for mounting in front of the eye, comprising a display device, a reflective / refracting optical system, and a light source, wherein the reflective / refracting optical system is positioned opposite the display surface of the display device, the display device has pixels having light-emitting elements and light-receiving elements, the reflective / refracting optical system comprises a first half-mirror and a second half-mirror, the first half-mirror has the function of transmitting visible light and semi-transmitting / semi-reflecting infrared light, the second half-mirror has the function of transmitting infrared light and semi-transmitting / semi-reflecting visible light, the reflective / refracting optical system has the function of imaging the visible light emitted by the light-emitting elements onto the retina of the eye, and the electronic device has the function of imaging the infrared light emitted by the light source and reflected from the surface of the eye onto a light-receiving element.

2. The reflective-refracting optical system according to claim 1, the electronic device having a configuration in which a linear polarizer, a first phase difference plate, one of the first half mirror and the second half mirror, the other of the first half mirror and the second half mirror, a second phase difference plate, and a reflective polarizer are arranged in that order in one direction from the display device side.

3. The electronic device according to claim 1, wherein a support is provided between the first half mirror and the second half mirror to support the first half mirror and the second half mirror, respectively.

4. The electronic device according to claim 1, wherein the first half-mirror and the second half-mirror each have a concave surface, and the curvature of the first half-mirror is greater than the curvature of the second half-mirror.

5. An electronic device for mounting in front of the eye, comprising a display device, a reflective / refracting optical system, and a light source, wherein the reflective / refracting optical system is positioned opposite the display surface of the display device, the display device has pixels having light-emitting elements and light-receiving elements, the reflective / refracting optical system comprises a first reflective polarizer and a second reflective polarizer, the first reflective polarizer has the function of transmitting infrared light, transmitting a first linearly polarized light in visible light, and reflecting a second linearly polarized light orthogonal to the first linearly polarized light, the second reflective polarizer has the function of transmitting visible light, transmitting a third linearly polarized light in infrared light, and reflecting a fourth linearly polarized light orthogonal to the third linearly polarized light, the reflective / refracting optical system has the function of imaging visible light emitted by the light-emitting element onto the retina of the eye, and the electronic device has the function of imaging infrared light emitted by the light source and reflected from the surface of the eye onto a light-receiving element.

6. The electronic device according to claim 5, wherein the reflective and refractive optical system has a configuration in which a linear polarizer, a first phase difference plate, a half mirror, a second phase difference plate, one of the first reflective polarizer and the second reflective polarizer, and the other of the first reflective polarizer and the second reflective polarizer are arranged in that order in one direction from the display device side.

7. An electronic device according to any one of claims 1 to 6, wherein the pixel has a transistor connected to the light-emitting element and the light-receiving element, and the transistor has a metal oxide in the channel-forming region.

8. The electronic device according to claim 7, wherein the metal oxide is indium oxide.

Images