Display device and optical system

Abstract

The present invention prevents deterioration of image quality of a display image. A display device according to the present disclosure comprises an image display unit, a light guide unit, a light source unit, an imaging unit, and a diffraction element. The image display unit displays an image. The light guide unit light-guides the image to the eyeball of the user. The light source unit irradiates the face of the user with light. The imaging unit acquires the reflected light from the irradiated light reflected by the eyeball. The diffraction element is disposed between the image display unit and the light guide unit and diffracts the reflected light toward the imaging unit.

Description

Display device and optical system

[0001] The present disclosure relates to a display device and an optical system.

[0002] Systems are being used in virtual reality (VR), augmented reality (AR), etc. that detect a user's line of sight and apply the detected line of sight to a user interface (UI), etc. For example, a device has been proposed that has a function of detecting a user's line of sight in a display device such as a head-mounted display (HMD) worn by a user (see, for example, Patent Document 1).

[0003] This device estimates the gaze using a method called video oculography (VOG), which uses a light source that irradiates the eyeball with infrared light and an image sensor that generates an image based on the light reflected from the eyeball. VOG estimates the eyeball direction from the relative positions of the pupil and corneal reflex (Purkinje image) in the image. To improve the accuracy of gaze detection, it is necessary to accurately acquire the position of the pupil in the image of the eyeball. Typically, a method is used in which the image sensor is positioned near the front of the eyeball to reduce the angle of view of the image sensor (here, the angle of incidence of reflected light). In the above-mentioned device, a diffraction element is positioned in front of the eyeball, which diffracts the reflected light and guides it to the image sensor, thereby reducing the angle of view.

[0004] International Publication No. 2021 / 117409

[0005] However, in the above-mentioned conventional technology, the display image projected onto the user's eyeball is affected by the diffraction element, resulting in a problem of degradation in the quality of the display image.

[0006] Therefore, the present disclosure proposes a display device and an optical system that prevent degradation in the quality of a displayed image.

[0007] The display device according to the present disclosure includes an image display unit that displays an image, a light guide unit that guides the image to a user's eyeball, a light source unit that irradiates light onto the eyeball, an imaging unit that generates an image based on light reflected from the irradiated light by the eyeball, and a diffraction element that is disposed between the image display unit and the light guide unit and diffracts the reflected light toward the imaging unit.

[0008] 1 is a diagram illustrating an example of gaze detection according to the first embodiment of the present disclosure. FIG. 1 is a diagram illustrating an example of gaze detection according to the first embodiment of the present disclosure. FIG. 2 is a diagram illustrating an example of gaze detection according to the first embodiment of the present disclosure. FIG. 3 is a diagram illustrating an example of a display device according to the first embodiment of the present disclosure. FIG. 4 is a diagram illustrating an example of generation of a reflected light image in a conventional display device. FIG. 5 is a diagram illustrating an example of generation of a reflected light image in a conventional display device. FIG. 6 is a diagram illustrating an example of a display image in a conventional display device. FIG. 7 is a diagram illustrating an example of a display image in a conventional display device. FIG. 8 is a diagram illustrating an example of a display image in a conventional display device. FIG. 9 is a diagram illustrating an example of a display image in a conventional display device. FIG. 10 is a diagram illustrating another example of a display image in a display device according to the first embodiment of the present disclosure. FIG. 11 is a diagram illustrating another example of a display image in a display device according to the first embodiment of the present disclosure. FIG. 12 is a diagram illustrating another example of a configuration of a display device according to a second embodiment of the present disclosure. FIG. 13 is a diagram illustrating another example of a configuration of a display device according to the second embodiment of the present disclosure. FIG. 14 is a diagram illustrating another example of a configuration of a display device according to the second embodiment of the present disclosure. FIG. 1 is a diagram showing another configuration example of a display device according to a second embodiment of the present disclosure. FIG. 2 is a diagram showing a configuration example of a diffraction element according to a second embodiment of the present disclosure. FIG. 3 is a diagram showing a configuration example of a diffraction element according to a second embodiment of the present disclosure. FIG. 4 is a diagram showing a configuration example of a light source unit according to a second embodiment of the present disclosure. FIG. 5 is a diagram showing a configuration example of a light source unit according to a second embodiment of the present disclosure. FIG. 6 is a diagram showing a configuration example of a display device according to a third embodiment of the present disclosure. FIG. 7 is a diagram showing a configuration example of a display device according to a third embodiment of the present disclosure.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be given in the following order. Note that in the following embodiments, the same components are designated by the same reference numerals, and redundant description will be omitted. 1. First embodiment 2. Second embodiment 3. Configuration of display device

[0010] 1A to 1C are diagrams illustrating an example of gaze detection according to a first embodiment of the present disclosure. The diagrams are diagrams for explaining gaze detection in a display device of the present disclosure.

[0011] FIG. 1A is a diagram illustrating an example of the gaze detection system using the VOG described above. The left side of the figure is a diagram illustrating a cross section of an eyeball 200. The eyeball 200 includes a spherical sclera 201, a cornea 202, and an iris 203. The right side of the figure illustrates a light source unit 130 that irradiates the eyeball 200 with infrared light and an image capture unit 140 that generates an image based on the reflected light. The light source unit 130 and the image capture unit 140 are arranged in a frame 19. The figure illustrates an example in which four light source units 130 are arranged. Note that an image display unit (an image display unit 110, described later) that projects an image onto the eyeball is arranged on the right side of the frame 19 in the figure.

[0012] 1B is a diagram of an eyeball 200 viewed from the front. In the image of the eyeball 200, an iris 203 and a pupil 204 behind a cornea 202 are arranged. In addition, the image in the same figure also has Purkinje images 210 formed by the light source units 130 arranged according to the number of light source units 130. The line of sight can be detected based on the positions of the iris 203, pupil 204, and Purkinje images 210.

[0013] FIG. 1C is a diagram showing an example of gaze detection. The left side of the figure shows the iris 203, pupil 204, and Purkinje image 210 in the case of right rotation. The center of the figure shows the iris 203, etc. in the case of central gaze. The right side of the figure shows the iris 203, etc. in the case of left rotation. As described above, the positions and shapes of the iris 203, pupil 204, and Purkinje image 210 change depending on the orientation of the eyeball 200. Therefore, the orientation of the eyeball can be estimated from the positions and shapes of the iris 203, pupil 204, and Purkinje image 210. For example, the gaze can be detected by a polynomial fitting method of the pupil-corneal reflex or a model estimation method of the pupil-corneal reflex.

[0014] 1A , the image capturing unit 140 is disposed on the frame 19. In this case, the image capturing unit 140 captures reflected light with the image capturing axis tilted, which causes a problem that a sufficient number of Purkinje images 210 cannot be acquired when the eyeball 200 rotates. For this reason, it is necessary to reduce the angle of view of the image capturing unit 140.

[0015] <Configuration of Display Device> Fig. 2 is a diagram illustrating an example of a display device according to a first embodiment of the present disclosure. The diagram illustrates a configuration example of a display unit 100 included in the display device of the present disclosure. Note that a user's eyeball 200 is depicted on the left side of the diagram. The display unit 100 includes an image display unit 110, a light guide unit 120, light source units 130 and 131, an imaging unit 140, and a diffraction element 150. Note that the light guide unit 120 and the diffraction element 150 constitute an optical system.

[0016] The image display unit 110 displays an image. This displayed image is referred to as a display image. This display image is projected onto the eyeball 200. The solid arrows in the figure represent the light of the display image projected onto the eyeball 200. The image display unit 110 can be configured, for example, by an organic EL (Electro Luminescence) display or an LCD (Liquid Crystal Display).

[0017] The light guide unit 120 guides the light of the display image to the eyeball 200. The light guide unit 120 in the figure includes a lens 121. The lens 121 focuses the light of the display image onto the eyeball 200. As will be described later, the light guide unit 120 can also be configured with a plurality of lenses. Also, a pancake lens optical system can be used as the light guide unit 120.

[0018] The light source units 130 and 131 irradiate light onto the user's face, including the eyeball 200. The light source units 130 and 131 serve as light sources when the imaging unit 140 captures an image. At least one light source unit 130 can be provided. As described in FIG. 1, three or more light source units can also be provided.

[0019] Light sources that emit invisible light can be used for the light source units 130 and 131, etc. In this case, the light from the light source units 130, etc. is not noticeable to the user, thereby improving convenience. It is also preferable to use a light source that emits infrared light for the light source units 130, etc. This is because infrared light has a high reflectance at the pupil 204 and can generate a clear image of reflected light. The light source units 130, etc. can be configured, for example, with a light-emitting diode (LED) or a laser diode.

[0020] The imaging unit 140 acquires reflected light that is light emitted from the light source unit 130 or the like and reflected by the eyeball 200. The imaging unit 140 can generate an image based on the acquired reflected light. This image is called a reflected light image. The imaging unit 140 includes, for example, an imaging element that captures infrared light, and generates and outputs the reflected light image. The same figure shows an example in which the imaging unit 140 is disposed between the eyeball 200 and the light guide unit 120. Note that, for example, a MOS (Metal Oxide Semiconductor) type or a CCD (Charge Coupled Device) type imaging element or an EVS (Event-based Vision Sensor) can be used as the imaging element.

[0021] The diffraction element 150 diffracts the light reflected from the eyeball 200 toward the image capture unit 140. This diffraction element 150 is disposed between the image display unit 110 and the light guide unit 120. The dashed arrows in the figure represent reflected light. As shown in the figure, the diffraction element 150 disposed in front of the eyeball 200 can change the optical path of the reflected light traveling straight toward the image capture unit 140. This allows the aforementioned angle of view to be reduced. Furthermore, a diffraction element designed to match the wavelength range of the light emitted by the light source unit 130 can be used as the diffraction element 150. In other words, if the light source unit 130 emits infrared light, a diffraction element 150 capable of diffracting infrared light can be used. The diffraction element 150 in the figure represents an example configured in a flat plate shape.

[0022] The diffraction element 150 can be configured with a diffraction grating. The diffraction element 150 in the figure shows an example in which a reflective diffraction grating is used. It is also preferable to use a diffraction grating that diffracts infrared light and reduces the diffraction of visible light as the diffraction element 150. This is because this does not prevent the light of the display image from being incident on the light guide unit 120. For example, a holographic optical element (HOE) can be used as the diffraction grating.

[0023] By using a light source unit 130 compatible with infrared light, a diffraction element 150, and an imaging unit 140, it is possible to prevent the user from perceiving the light used for gaze detection. However, a diffraction element 150 designed to diffract infrared light also has diffraction capabilities in the visible light band. As a result, the light of the displayed image may also be diffracted, resulting in a loss of image quality. However, by disposing the diffraction element 150 between the image display unit 110 and the light guide unit 120, the diffraction of the light of the displayed image can be reduced. This is because the incident angle of visible light on the diffraction element 150 deviates from the diffraction condition of the diffraction element 150. As indicated by the solid arrow in Figure 2, the light of the displayed image before passing through the light guide unit 120 is incident on the diffraction element 150. This reduces the incident angle of the light of the displayed image on the diffraction element 150, making it less likely to be diffracted.

[0024] On the other hand, the reflected light represented by the dashed arrow passes through the light guiding section 120 and then enters the diffraction element 150, and therefore the angle of incidence on the diffraction element 150 is large. Therefore, the reflected light is diffracted and enters the imaging section 140.

[0025] 3A to 3C are diagrams showing an example of generation of a reflected light image in a conventional display device. The figures are presented as a comparative example of the display device of the present disclosure. In FIGS. 3A to 3C, thin arrows represent the optical path of light from the image display unit 110, and thick arrows represent the optical path of reflected light. Note that the light source unit 130 is not shown in FIGS. 3A to 3C.

[0026] FIG. 3A shows an example of a display unit 100 including an image display unit 110, a light guide unit 120, and an image capture unit 140, in which the image capture unit 140 is disposed near the end of the light guide unit 120.

[0027] 3B shows an example of a display unit 100 including an image display unit 110, a light guide unit 120, and an image capture unit 140, in which the image capture unit 140 is disposed near an end of the image display unit 110. As shown in the figure, the angle of view is smaller than in the case of FIG. 3A.

[0028] FIG. 3C shows an example of a display unit 100 equipped with a diffraction element 150. The optical path of the reflected light is changed by the action of the diffraction element 150. Because the reflected light is incident on the diffraction element 150 from a direction substantially perpendicular to the diffraction element 150, the angle of view is further reduced compared to the case of FIG. 3B. However, unlike the display unit 100 of FIG. 2, the light of the display image that has passed through the light guide unit 120 is incident on the diffraction element 150, and therefore a portion of the light of the display image is diffracted by the diffraction element 150, resulting in a degradation in the image quality. The dashed arrows in the figure represent the light of the display image diffracted by the diffraction element 150. The degradation in image quality of the display image caused by the diffraction element 150 will be explained using FIGS. 4A-4C.

[0029] 4A-4C are diagrams showing examples of display images in conventional display devices. In FIGS. 4A-4C, the left side shows the configuration of each display device. Note that the light guide unit 120 and image display unit 110 are omitted. In the left-hand diagrams, the solid arrows represent the optical path of light from the image display unit 110. The dotted hatched area represents light from the image display unit 110. The thick dashed line represents a virtual subject position 220 in the image capture unit 140. The dotted arrow represents the optical path of reflected light incident on the image capture unit 140. In FIGS. 4A-4C, the right side shows display images generated by simulation.

[0030] 4A shows an example without a diffraction element, and the image displayed on the right shows the reference image.

[0031] 4B shows an example in which a transmissive diffraction element 211 is disposed between the eyeball 200 and the light guide unit 120 (not shown). In this case, the imaging unit 140 is disposed between the diffraction element 211 and the light guide unit 120 (not shown). As shown in the diagram on the left, part of the light from the image display unit 110 is diffracted by the diffraction element 211, changing the optical path. Therefore, as shown in the diagram on the right, the displayed image changes.

[0032] 4C shows an example in which a reflective diffraction element 212 is disposed between the eyeball 200 and the light guide unit 120 (not shown). In this case, the imaging unit 140 is disposed between the eyeball 200 and the diffraction element 212. As shown in the diagram on the left, part of the light from the image display unit 110 is diffracted by the diffraction element 211, changing the optical path. Therefore, as shown in the diagram on the right, the displayed image changes.

[0033] Even if the diffractive elements 211 and 212 are designed for non-visible wavelengths, the wavelength band they affect extends to visible light, which can diffract the light of the displayed image and degrade image quality. Increasing the film thickness of the diffractive element to narrow the band can reduce the amount of diffracted light in visible light. However, because light with a wide angle of view is incident on the diffractive element, light loss and stray light occur due to the diffraction of the light of the displayed image. Therefore, avoiding the diffraction of the display image light is a challenge when using axial eye tracking with a diffractive element.

[0034] 5A is a diagram showing an example of a display image in the display device according to the first embodiment of the present disclosure. The figure shows an example of a display image in the display device 1. In the figure, the left side shows the configuration of the display unit 100. The display unit 100 in the figure includes an image display unit 110, a light guide unit 120, and a diffraction element 150. The dotted hatched area represents light from the image display unit 110. The right side of the figure shows a display image generated by simulation. As shown on the right side of the figure, the display unit 100 of the display device 1 can obtain a display image similar to the reference image in FIG. 4A.

[0035] 5B is a diagram showing another example of a display image in the display device according to the first embodiment of the present disclosure. This figure illustrates an example in which the diffractive element 150 is disposed between the eyeball 200 and the light guide unit 120 in the display unit 100 of the display device 1, and is described as a comparative example. As with FIG. 5A , the left side illustrates the configuration of the display unit 100, and the right side illustrates a display image generated by simulation. As shown in the figure, when the diffractive element 150 is disposed between the eyeball 200 and the light guide unit 120, a portion of the visible light from the image display unit 110 is diffracted by the diffractive element 150, changing the optical path and causing distortion in the displayed image. The hollow arrow on the right side of the figure indicates the portion where this distortion (diffraction of visible light) occurs.

[0036] In this way, by disposing the diffraction element 150 between the image display section 110 and the light guide section 120, the influence of the diffraction element 150 on the displayed image can be reduced.

[0037] 6A and 6B are diagrams illustrating another example of the display device according to the first embodiment of the present disclosure. 6A and 6B are diagrams illustrating another example of the configuration of the display unit 100 included in the display device according to the present disclosure.

[0038] 6A shows an example in which the light source units 130 and 131 are arranged between the diffraction element 150 and the light guiding unit 120. Also, FIG. 6B shows an example in which the light source units 130 and 131 are arranged between the image display unit 110 and the diffraction element 150.

[0039] As described above, in the display device according to the first embodiment of the present disclosure, the diffraction element 150 that diffracts reflected light from the display unit 100 toward the image capture unit 140 is disposed between the image display unit 110 and the light guide unit 120. This reduces the diffraction of light of the displayed image by the diffraction element 150, thereby preventing a decrease in the quality of the displayed image. Furthermore, it is possible to reduce light loss and the occurrence of stray light.

[0040] (2. Second Embodiment) A variation of the display device of the first embodiment described above will be described.

[0041] 7A and 7B are diagrams illustrating a configuration example of a display device according to a second embodiment of the present disclosure. Similar to FIG. 2, FIG. 7A and 7B are diagrams illustrating a configuration example of a display unit 100. The display unit 100 in FIG. 7A and 7B differs from the display unit 100 in FIG. 2 in that the diffraction element 150 is disposed adjacent to the light guide unit 120.

[0042] 7A shows an example of a flat diffraction element 150. FIG. 7B shows an example of a curved cross-section of the diffraction element 150. The diffraction element 150 in FIG. 7B can be configured to have the same curved surface as the surface of the lens 121 of the light guiding section 120.

[0043] 8 is a diagram showing another configuration example of a display device according to a second embodiment of the present disclosure. Similar to FIG. 7A, this diagram shows a configuration example of the display unit 100. The display unit 100 in this diagram differs from the display unit 100 in FIG. 7A in that the light source units 130 and 131 are disposed between the image display unit 110 and the diffraction element 150.

[0044] 9A and 9B are diagrams illustrating another configuration example of a display device according to a second embodiment of the present disclosure. Similar to FIG. 2, FIG. 9A and 9B are diagrams illustrating a configuration example of a display unit 100. The display unit 100 in FIG. 9A and 9B differs from the display unit 100 in FIG. 2 in that a diffraction element 150 is disposed adjacent to the image display unit 110.

[0045] 9A shows an example in which light source units 130 and 131 are disposed between light guide unit 120 and eyeball 200. Also, FIG. 9B shows an example in which light source units 130 and 131 are disposed between diffraction element 150 and light guide unit 120.

[0046] 10A and 10B are diagrams showing another configuration example of a display device according to a second embodiment of the present disclosure. Fig. 10A is a diagram showing a configuration example of a display unit 100, similar to Fig. 2. The display unit 100 in Fig. 10A shows an example in which a diffraction element 150 is disposed inside a light guiding unit 120. Specifically, the diffraction element 150 in the figure is configured to be included in a lens 121 of the light guiding unit 120.

[0047] 10B is an enlarged view of the light guide unit 120 in FIG. 10A. The solid arrows in the figure represent the light trails of the light of the displayed image. As shown in the figure, the angle of the light rays becomes small inside an optical element such as the lens 121, resulting in a small angle of incidence on the diffraction element 150. This makes it possible to further reduce the diffraction of the light of the displayed image.

[0048] 11A and 11B are diagrams illustrating another configuration example of a display device according to a second embodiment of the present disclosure. Like FIG. 2, Fig. 11A is a diagram illustrating a configuration example of a display unit 100. The display unit 100 in Fig. 11A includes a light guide unit 120 having a plurality of lenses (lenses 121 and 122), and illustrates an example in which a diffraction element 150 is disposed between the lenses 121 and 122.

[0049] 11B is an enlarged view of the light guide unit 120 in FIG. 11A. The solid arrows in the figure represent the light trails of the light of the displayed image. As shown in the figure, the angle of the light rays becomes gentler between the lenses 121 and 122. As with the diffraction element 150 in FIG. 10B, the angle of incidence on the diffraction element 150 becomes small. This allows for further reduction in the diffraction of the light of the displayed image.

[0050] 11A, only lens 121 can be regarded as light guiding section 120. In this case, lens 122 constitutes a second light guiding section that is a light guiding section different from light guiding section 120. Also, as shown in FIG. 10A, even in a configuration in which one lens 121 is divided by diffraction element 150 to provide two lenses, this can be regarded as a configuration having light guiding section 120 and a second light guiding section.

[0051] 12A and 12B are diagrams illustrating an example configuration of a diffraction element according to a second embodiment of the present disclosure. FIGS. 12A and 12B are diagrams illustrating variations of the diffraction element 150. The diffraction element 150 in FIG. 12A is an example of a diffraction element 150 that uses a reflective diffraction grating, similar to the diffraction element 150 in FIG. 2 . The diffraction element 150 in FIG. 12B is an example of a diffraction element 150 that uses a transmissive diffraction grating. In either diffraction element 150, reflected light is diffracted toward the imaging unit 140.

[0052] 13A and 13B are diagrams illustrating configuration examples of a light source unit according to a second embodiment of the present disclosure, and are diagrams illustrating variations in the arrangement of the light source unit 130 and the like.

[0053] 13A and 13B show examples of light source unit 130 and the like arranged inside light guiding unit 120. Fig. 13A shows an example in which light guiding unit 120 includes lens 121, and light source units 130 and 131 are arranged inside lens 121. Fig. 13B shows an example in which light guiding unit 120 includes lens 121 and lens 122, and light source units 130 and 131 are arranged between lens 121 and lens 122.

[0054] The configuration of the display unit 100 other than that described above is the same as the configuration of the display unit 100 in the first embodiment of the present disclosure, and therefore description thereof will be omitted.

[0055] In the display unit 100 of the second embodiment of the present disclosure, the angle of incidence of visible light on the diffraction element can be set to the same as in the display unit 100 of the first embodiment of the present disclosure. As a result, the display unit 100 of the second embodiment of the present disclosure achieves the same effects as the display unit 100 of the first embodiment of the present disclosure.

[0056] (3. Configuration of Display Device) The display unit 100 of the first embodiment described above can be applied to various devices. An example in which the display unit 100 is applied to a display device will be described.

[0057] <Configuration of Display Device> Fig. 14 is a diagram showing a configuration example of a display device according to a third embodiment of the present disclosure. The figure is a block diagram showing a configuration example of a display device 10. Note that the figure shows eyeballs 200a and 200b corresponding to both eyes of a user. The display device 10 includes display units 100a and 100b, a display control unit 20, and a gaze detection unit 30.

[0058] The display units 100a and 100b are display units 100 corresponding to the eyeballs 200a and 200b, respectively.

[0059] The display control unit 20 controls the image display units 110 of the display units 100a and 100b. The display control unit 20 generates a control signal including an image signal of an image to be displayed, and outputs the control signal to each of the image display units 110.

[0060] The gaze detection unit 30 detects the gaze of the user. This gaze detection unit 30 estimates the eyeball position and detects the gaze based on images from the imaging units 140 of the display units 100a and 100b. The gaze detection unit 30 can output the detection result to an external application processor or the like.

[0061] FIG. 15 is a diagram illustrating an example of the configuration of a display device according to a third embodiment of the present disclosure. The diagram illustrates an example of a display device 10 configured as a head-mounted display (HMD). This head-mounted display is a display device worn on the head. The display device 10 in the diagram includes a housing 11 and is fixed to a person's head using an attachment belt 12 disposed on the housing 11. Display units 100a and 100b are disposed inside the housing 11. Images can be displayed on the display units 100a and 100b, allowing the user to view augmented reality (AR) or virtual reality (VR) images. The attachment belt 12 is an example of a "wearing unit" in the present disclosure.

[0062] The display device 10 shown in the figure is used by placing the rear side of the housing 11 against a person's face. The display device 10 shown in the figure is configured to cover the user's eyes, shielding the user from the outside world. The display units 100a and 100b can, for example, display images of the outside world. The display units 100a and 100b can constantly grasp the physical space around the user and generate an image that interacts with the physical space to show the user. For example, an image in which an image of a virtual object is superimposed on an image of the surroundings can be generated and displayed. This type of technology is called mixed reality (MR).

[0063] In this embodiment, a system refers to a collection of multiple components (devices, modules (components), etc.), regardless of whether all of the components are in the same housing. Therefore, multiple devices housed in separate housings and connected via a network, and a single device in which multiple modules are housed in a single housing, are both systems.

[0064] Furthermore, for example, this embodiment can have a cloud computing configuration in which one function is shared and processed jointly by a plurality of devices via a network.

[0065] Although the embodiments of the present disclosure have been described above, the technical scope of the present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present disclosure. Furthermore, components of different embodiments and modifications may be combined as appropriate.

[0066] The series of processes performed by each device described in this specification may be realized using software, hardware, or a combination of software and hardware. The programs constituting the software are stored in advance, for example, in a storage medium (non-transitory medium) provided inside or outside each device. Then, each program is loaded into RAM when executed by a computer, and executed by a processor such as a CPU.

[0067] (Effect) The display device includes an image display unit that displays an image, a light guide unit that guides the image to a user's eyeball, a light source unit that irradiates the eyeball with light, an imaging unit that generates an image based on light reflected from the irradiated light by the eyeball, and a diffraction element that is disposed between the image display unit and the light guide unit and diffracts the reflected light toward the imaging unit. This provides the effect of preventing diffraction of light from the image display unit while reducing the angle of view of the imaging unit. As a result, it is possible to prevent degradation of image quality.

[0068] The light source unit may emit invisible light, and the imaging unit may generate the image based on the reflected invisible light. This improves convenience for the user.

[0069] The light source unit may emit infrared light, and the imaging unit may generate the image based on the reflected infrared light. This allows a clear image of the reflected light to be generated, thereby improving the accuracy of gaze detection.

[0070] The diffraction element may be disposed adjacent to the light guide section, thereby simplifying the configuration of the display device.

[0071] The diffraction element may be disposed adjacent to the image capturing section, thereby simplifying the configuration of the display device.

[0072] Furthermore, a plurality of the light source units may be arranged, thereby improving the accuracy of gaze detection.

[0073] The light source unit may be disposed between the eyeball and the light guide unit, thereby reducing reflection of light from the light source unit by the light guide unit and reducing generation of stray light.

[0074] The light source section may be disposed between the light guide section and the diffraction element.

[0075] The light source unit may be disposed between the diffraction element and the image display unit.

[0076] The light guide may include an optical lens.

[0077] The light guide section may include a plurality of the optical lenses, thereby improving the light-collecting ability of the light from the image display section.

[0078] The optical element may further include a second light guide section disposed between the diffraction element and the image display section, thereby improving the effect of preventing diffraction of light from the image display section.

[0079] The imaging unit may be disposed between the eyeball and the diffraction element, and the diffraction element may diffract the reflected light in a reflection direction. This allows the image display unit, the diffraction element, and the light guide unit to be made thinner.

[0080] The imaging unit may be disposed between the diffraction element and the image display unit, and the diffraction element may diffract the reflected light in a transmission direction, thereby reducing the amount of light incident on the imaging unit from the image display unit.

[0081] The diffraction element may be formed in a flat plate shape, which can reduce the cost of the diffraction element.

[0082] The diffraction element may be curved, so that it can be configured to match the shape of the lens or the like of the light guide portion.

[0083] The display device may further include a plurality of display units each including the image display unit, the light guide unit, the light source unit, the imaging unit, and the diffraction element, and the plurality of display units may correspond to the right eye and the left eye of the user, respectively. This allows the display device to correspond to both eyes of the user.

[0084] The display device may further include a housing in which the image display unit, the light guide unit, the light source unit, the imaging unit, and the diffraction element are arranged, and a mounting unit for mounting the housing on the head of the user, thereby making it a head-mounted display device.

[0085] The optical system includes a light guide unit that guides an image displayed on an image display unit to a user's eyeball, and a diffraction element disposed between the image display unit and the light guide unit that diffracts reflected light toward an imaging unit that generates an image using light reflected from the eyeball, the light having been irradiated by a light source unit that irradiates the eyeball. This prevents diffraction of light from the image display unit while reducing the angle of view of the imaging unit. This prevents degradation of image quality.

[0086] The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0087] The present technology may also be configured as follows. (1) A display device having an image display unit that displays an image, a light guide unit that guides the image to a user's eyeball, a light source unit that irradiates light onto the user's face, an imaging unit that acquires reflected light of the irradiated light reflected by the eyeball, and a diffraction element that is disposed between the image display unit and the light guide unit and diffracts the reflected light toward the imaging unit. (2) The display device according to (1), wherein the light source unit irradiates invisible light, and the imaging unit acquires the reflected light of the invisible light. (3) The display device according to (2), wherein the light source unit irradiates infrared light, and the imaging unit acquires the reflected light of the infrared light. (4) The display device according to any of (1) to (3), wherein the diffraction element is disposed adjacent to the light guide unit. (5) The display device according to any of (1) to (3), wherein the diffraction element is disposed adjacent to the imaging unit. (6) The display device according to any one of (1) to (5), wherein a plurality of the light source units are arranged. (7) The display device according to any one of (1) to (6), wherein the light source unit is arranged between the eyeball and the light guiding unit. (8) The display device according to any one of (1) to (6), wherein the light source unit is arranged between the light guiding unit and the diffraction element. (9) The display device according to any one of (1) to (6), wherein the light source unit is arranged between the diffraction element and the image display unit. (10) The display device according to any one of (1) to (9), wherein the light guiding unit includes an optical lens. (11) The display device according to (10), wherein the light guiding unit includes a plurality of the optical lenses. (12) The display device according to any one of (1) to (3), further including a second light guiding unit arranged between the diffraction element and the image display unit. (13) The display device according to any one of (1) to (12), wherein the imaging unit is disposed between the eyeball and the diffraction element, and the diffraction element diffracts the reflected light in a reflection direction. (14) The display device according to any one of (1) to (12), wherein the imaging unit is disposed between the diffraction element and the image display unit, and the diffraction element diffracts the reflected light in a transmission direction. (15) The display device according to any one of (1) to (14), wherein the diffraction element is configured in a flat plate shape.(16) The display device according to any one of (1) to (4), wherein the diffraction element is configured in a curved shape. (17) The display device according to any one of (1) to (16), comprising a plurality of display units, each including the image display unit, the light guiding unit, the light source unit, the imaging unit, and the diffraction element, wherein the plurality of display units correspond to the right eye and the left eye of the user, respectively. (18) The display device according to any one of (1) to (17), further comprising: a housing in which the image display unit, the light guiding unit, the light source unit, the imaging unit, and the diffraction element are arranged; and a wearing unit for wearing the housing on the head of the user. (19) An optical system having: a light guiding unit that guides an image of an image display unit that displays an image to an eyeball of the user; and a diffraction element that is arranged between the image display unit and the light guiding unit and diffracts the reflected light toward an imaging unit that generates an image by light reflected from the eyeball, the light source unit irradiating light onto the eyeball.

[0088] 10 Display device 100, 100a, 100b Display unit 120 Light guide unit 121, 122 Lens 130 Light source unit 140 Imaging unit 150 Diffraction element 200, 200a, 200b Eyeball

Claims

1. A display device having an image display unit that displays an image, a light guide unit that guides the image to a user's eyeball, a light source unit that irradiates light onto the user's face, an imaging unit that acquires reflected light from the irradiated light that is reflected by the eyeball, and a diffraction element that is positioned between the image display unit and the light guide unit and diffracts the reflected light toward the imaging unit.

2. The display device according to claim 1, wherein the light source unit emits invisible light, and the imaging unit acquires the reflected light of the invisible light.

3. The display device according to claim 2, wherein the light source unit emits infrared light, and the imaging unit acquires the reflected light of the infrared light.

4. The display device according to claim 1, wherein the diffraction element is disposed adjacent to the light guide section.

5. The display device according to claim 1, wherein the diffraction element is disposed adjacent to the imaging section.

6. The display device according to claim 1, wherein a plurality of said light source sections are arranged.

7. The display device according to claim 1, wherein the light source section is disposed between the eyeball and the light guide section.

8. The display device according to claim 1, wherein the light source section is disposed between the light guide section and the diffraction element.

9. The display device according to claim 1, wherein the light source section is disposed between the diffraction element and the image display section.

10. The display device according to claim 1, wherein the light guide comprises an optical lens.

11. The display device according to claim 10, wherein the light guide section comprises a plurality of the optical lenses.

12. The display device according to claim 1, further comprising a second light guide section disposed between the diffraction element and the image display section.

13. The display device according to claim 1, wherein the imaging unit is disposed between the eyeball and the diffraction element, and the diffraction element diffracts the reflected light in a reflection direction.

14. The display device according to claim 1, wherein the imaging unit is disposed between the diffraction element and the image display unit, and the diffraction element diffracts the reflected light in a transmission direction.

15. The display device according to claim 1, wherein the diffraction element is formed in a flat plate shape.

16. The display device according to claim 1, wherein the diffraction element is configured in a curved shape.

17. The display device according to claim 1, comprising a plurality of display units each including the image display unit, the light guide unit, the light source unit, the imaging unit, and the diffraction element, the plurality of display units corresponding to the right and left eyes of the user, respectively.

18. The display device according to claim 1, further comprising: a housing in which the image display unit, the light guide unit, the light source unit, the imaging unit, and the diffraction element are arranged; and a mounting unit for mounting the housing on the user's head.

19. An optical system having a light guide unit that guides an image from an image display unit that displays an image to a user's eyeball, and a diffraction element that is disposed between the image display unit and the light guide unit and that diffracts the reflected light toward an imaging unit that generates an image using light reflected from the eyeball by light irradiated from a light source unit that irradiates light onto the user's face.

Images