Head-mounted display

Abstract

A head-mounted display (1) comprises: a first display panel (10) that displays a first display image (D1) having a first resolution; a second display panel (20) that displays a second display image (D2) having a second resolution higher than the first resolution; an optical mirror (30) that transmits at least a part of first image light emitted from the first display panel (10), and reflects at least a part of second image light emitted from the second display panel (20); an eyepiece lens (40) which the first image light transmitted through the optical mirror (30) and the second image light reflected by the optical mirror (30) are made to enter, and which allows a user visually recognize a display image (D) that is based on the first display image (D1) and the second display image (D2); and an emission angle regulation means (50) that regulates the emission angle of the second image light with respect to a display surface of the second display panel (20).

Description

head-mounted display

[0001] The present disclosure relates to a head-mounted display.

[0002] As disclosed in Patent Document 1, a head-mounted display is known that has a display panel that displays an image and an optical system that includes a lens.

[0003] International Publication No. 2016 / 136657

[0004] The inventors of the present application are considering providing a head-mounted display that uses multiple display panels, including a display panel capable of displaying high-resolution images, and optical mirrors that reflect and transmit image light emitted from the display panels. In a configuration that uses multiple display panels and optical mirrors, there is a risk that image light may be emitted in an unintended direction, causing so-called ghosting and deteriorating image quality.

[0005] One object of the present disclosure is to provide a head-mounted display capable of suppressing degradation of image quality.

[0006] The head-mounted display proposed in the present disclosure comprises a first display panel that displays a first display image at a first resolution, a second display panel that displays a second display image at a second resolution higher than the first resolution, an optical mirror that transmits at least a portion of the first image light emitted from the first display panel and reflects at least a portion of the second image light emitted from the second display panel, an eyepiece that receives the first image light that has transmitted through the optical mirror and the second image light that has been reflected by the optical mirror and allows a user to view a display image based on the first display image and the second display image, and an emission angle control means that controls the emission angle of the second image light with respect to the display surface of the second display panel.

[0007] FIG. 1 is a perspective view showing an HMD according to the present embodiment; FIG. 2 is a diagram schematically showing the configuration of a display panel and an optical system according to the present embodiment; FIG. 3 is a diagram showing an example of a displayed image; FIG. 4 is a diagram showing an example in which a louver film is used as an emission angle restricting means; FIG. 5 is a diagram showing an example of an arrangement of a second display panel and an optical mirror; FIG. 6 is a diagram showing an example of an arrangement of a second display panel and an optical mirror;

[0008] An embodiment of the present invention (hereinafter referred to as the present embodiment) will be described below with reference to the drawings. In the following description, a head-mounted display 1 will be referred to as an "HMD (Head Mounted Display) 1." In the following description, the directions indicated by X1 and X2 in the drawings will be referred to as right and left, respectively, the directions indicated by Y1 and Y2 in the drawings will be referred to as up and down, respectively, and the directions indicated by Z1 and Z2 in the drawings will be referred to as forward and backward, respectively. These directions indicate the directions as seen by a user wearing the HMD 1.

[0009] [Overview of HMD 1] Fig. 1 is a perspective view showing an HMD according to this embodiment. The HMD 1 may have a wearing band that surrounds the user's head and a main body housing that is supported at the front of the wearing band. When the HMD 1 is worn by a user and in use, the HMD 1 covers the user's eyes. The main body housing contains components such as display panels and an optical system. The HMD 1 shown in Fig. 1 is an example, and the shapes of the wearing band and the main body housing are not limited to those shown.

[0010] Fig. 2 is a diagram schematically illustrating the configuration of the display panel and optical system in this embodiment. As shown in Fig. 2, the HMD 1 includes a first display panel 10, a second display panel 20, an optical mirror 30, and an eyepiece 40. The thick arrows in Fig. 2 indicate the traveling direction of orthogonal light of the image light. Orthogonal light is light that travels in a direction perpendicular to the display surface.

[0011] [First Display Panel 10] The first display panel 10 may display two-dimensional or three-dimensional images. The first display panel 10 may be, for example, a liquid crystal panel or an organic electroluminescence display device, but the type of the panel is not particularly limited.

[0012] [Second Display Panel 20] The second display panel 20 may display two-dimensional or three-dimensional images. The second display panel 20 may be, for example, a liquid crystal panel or an organic electroluminescence display device, but the type is not particularly limited. In this embodiment, an example will be described in which a micro OLED (Organic Light-Emitting Diode) display is used as the second display panel 20.

[0013] [Display Image D] Fig. 3 is a diagram showing an example of a display image, in which the display image D is formed based on the first display image D1 and the second display image D2.

[0014] The first display panel 10 displays a first display image D1. The second display panel 20 displays a second display image D2, which together with the first display image D1 forms a display image D. The second display image D2 preferably has a higher resolution than the first display image D1. For example, the resolution of the second display image D2 may be 4K (number of pixels: 3840 x 2160) or 8K (number of pixels: 7680 x 4320). The second display panel 20 may also be smaller than the first display panel 10. That is, the area of ​​the second display image D2 may be smaller than the area of ​​the first display image D1.

[0015] 3, the second display image D2 may be an image displayed in the center of the display image D, and the first display image D1 may be an image displayed in the periphery of the second display image D2. In this way, by arranging the high-resolution second display image D2 in an area where human visual sensitivity is high, the user U can view a high-quality image.

[0016] Furthermore, using a display panel with high resolution and a large display area increases costs, but by using the first display panel 10 and the second display panel 20 as in this embodiment, the costs required for the display panels can be reduced and the user U can view high-quality images.

[0017] In addition, the area of ​​the first display image D1 corresponding to the area where the second display image D2 is displayed may be left blank as shown in Figure 3, or an image identical to the second display image D2 may be displayed superimposed thereon.

[0018] [Optical Mirror 30] The optical mirror 30 has the function of transmitting at least a portion of the first image light emitted from the first display panel 10 and reflecting at least a portion of the second image light (emitted light) emitted from the second display panel 20.

[0019] 2, the coarsely hatched area indicates the area through which the first image light passes after being emitted from the first display panel 10 and transmitted through the optical mirror 30. As shown in FIG. 2, at least a portion of the first image light emitted from the first display panel 10 passes through the optical mirror 30 and enters the eyepiece 40.

[0020] 2, the finely hatched area indicates the area through which the second image light emitted from the second display panel 20 and reflected by the optical mirror 30 passes. As shown in FIG. 2, at least a portion of the second image light emitted from the second display panel 20 is reflected by the optical mirror 30 and enters the eyepiece 40.

[0021] [Eyepiece Lens 40] The eyepiece lenses 40 are convex lenses located in front of the right and left eyes of the user U when the HMD 1 is in use. The eyepiece lenses 40 refract the incident first image light and second image light and allow them to be incident on the retina of the user U. The eyepiece lenses 40 have the function of enlarging the images displayed on the first display panel 10 and the second display panel 20 so that the user can view them. The eyepiece lenses 40 are preferably positioned so that their optical axes 40C are perpendicular to the display surface of the first display panel 10. The eyepiece lenses 40 may be composed of two or more lenses. The eyepiece lenses 40 may also be Fresnel lenses or liquid crystal lenses.

[0022] [Liquid Crystal Control Film 50] In a configuration employing the first display panel 10, the second display panel 20, and the optical mirror 30, so-called ghosting may occur due to the second image light emitted from the second display panel 20, resulting in degradation of the image quality of the display image D. Specifically, ghosting may occur due to the second image light that is directly incident on the eyepiece 40 without passing through the optical mirror 30. In FIG. 2 , the optical paths of the second image light that cause ghosting are shown as optical paths P1 and P2. For example, the second image light passing through optical path P1 may cause ghosting in the first display image D1, and the second image light passing through optical path P2 may cause ghosting in the second display image D2. Therefore, in this embodiment, a configuration is adopted in which a liquid crystal control film 50, which serves as an emission angle restricting means, is provided on the display surface of the second display panel 20.

[0023] The liquid crystal control film 50 is a film that can reduce the amount of light emitted from the second display panel 20 depending on the direction of emission. For example, the liquid crystal control film 50 may block light emitted in a direction passing through optical path P1 or optical path P2 by changing the arrangement of liquid crystal molecules contained within the film. By providing the liquid crystal control film 50 on the display surface of the second display panel 20, it is possible to suppress the generation of image light passing through optical paths P1 and P2. As a result, it is possible to suppress deterioration in the quality of the displayed image D due to the occurrence of ghosting.

[0024] While the occurrence of ghosts can be suppressed by widening the range of oblique light blocked by the liquid crystal control film 50, this reduces the transmittance of the second image light through the liquid crystal control film 50. Therefore, for example, it is advisable to control the arrangement of liquid crystal molecules so that the liquid crystal control film 50 blocks oblique light that is inclined at an angle of 20° to 30° or more with respect to normal light.

[0025] [Other Examples of Emission Angle Restriction Means] In FIG. 2 , the liquid crystal control film 50 has been described as an example of the emission angle restriction means, but the present invention is not limited to this and may be any other means that has the function of restricting the emission angle of the second image light relative to the display surface of the second display panel 20. For example, the emission angle restriction means may be a film that can block oblique light and transmit perpendicular light by changing the arrangement of liquid crystal molecules in the liquid crystal panel. The emission angle restriction means may be, for example, a commercially available film that is generally used as an anti-peeping film. Furthermore, the emission angle restriction means is not limited to a film-like member and may be any optical component that has the function of reducing the amount of light emitted from the second display panel 20 depending on the emission direction.

[0026] FIG. 4 illustrates an example in which a louver film 150 is used as the emission angle restricting means. The louver film 150 includes multiple transmissive portions 150a and multiple light-shielding portions 150b, with the transmissive portions 150a and the light-shielding portions 150b arranged alternately. The transmissive portions 150a and the light-shielding portions 150b may be formed in a grid or stripe pattern in a plan view. The light-shielding portions 150b may be wall-shaped and have a predetermined height in the thickness direction of the louver film 150. By providing the louver film 150 on the display surface of the second display panel 20, the occurrence of ghosting can be suppressed. This is because the light-shielding portions 150b block the second image light emitted from the second display panel 20 in a direction oblique to the display surface. To more accurately suppress the occurrence of ghosting, it is preferable to increase the height of the light-shielding portions 150b in the thickness direction or increase the proportion of the light-shielding portions 150b in a plan view. In this case, the distance (pitch) between the walls of the louver film 150 is preferably, for example, 20 μm or less to prevent the walls from being visible to the user.

[0027] The second display panel 20 may also have a built-in function of reducing the amount of emitted light depending on the direction of emission. The second display panel 20 may also be a liquid crystal panel with a built-in function of changing the alignment of liquid crystal molecules. In this case, there is no need to provide a separate liquid crystal control film 50.

[0028] [Regarding the Arrangement of the Second Display Panel 20 and the Optical Mirror 30] In this embodiment, a half mirror having a transmission-to-reflection ratio of 1:1 for light of a specific wavelength is used as the optical mirror 30. In a side view, the inclination angle θ1 of the display surface of the first display panel 10 relative to the optical mirror 30 is set to be the same as the inclination angle θ2 of the display surface of the second display panel 20 relative to the optical mirror 30. This allows the first image light emitted from the first display panel 10 and the second image light emitted from the second display panel 20 to be incident on the optical mirror 30 at the same angle, thereby forming a desired display image D. The transmission-to-reflection ratio of the optical mirror 30 may be adjusted to an optimal ratio taking into account the luminance of the first display panel 10 and the second display panel 20.

[0029] 2 and 5 show an example in which the tilt angle θ1 = the tilt angle θ2 = 41°. Note that in Figs. 5 to 7, the straight line 10S indicates a plane along the display surface of the first display panel 10, and the straight line 20S indicates a plane along the display surface of the second display panel 20.

[0030] The first display panel 10, the second display panel 20, and the optical mirror 30 are preferably arranged so that the tilt angles θ1 and θ2 are less than 45°. Fig. 6 shows an example in which the tilt angles θ1 and θ2 are 45°, and Fig. 7 shows an example in which the tilt angles θ1 and θ2 are 30°.

[0031] 6, by making the inclination angles θ1 and θ2 relatively large, it is possible to increase the proportion of the second display image D2 in the display image D. This makes it possible for the user to view a high-quality display image.

[0032] 7, by making the tilt angles θ1 and θ2 relatively small, the second display panel 20 is positioned so that the tilt angle θ3 of its display surface with respect to a plane S perpendicular to the optical axis 40C of the eyepiece 40 is greater than 90°. This makes it difficult for the second image light emitted from the second display panel 20 to be directly incident on the eyepiece 40. Therefore, the range of the emission angle of the second image light regulated by the emission angle regulating means can be relaxed, and the transmittance of the emission angle regulating means can be improved.

[0033] The second display panel 20 is preferably disposed outside the field of view of the user U so that the panel itself is not visible to the user U.

[0034] [Note] For example, the head-mounted display may have the following configuration: (1) A head-mounted display including a first display panel that displays a first display image at a first resolution, a second display panel that displays a second display image at a second resolution higher than the first resolution, an optical mirror that transmits at least a portion of first image light emitted from the first display panel and reflects at least a portion of second image light emitted from the second display panel, an eyepiece that receives the first image light that has transmitted through the optical mirror and the second image light that has been reflected by the optical mirror and that allows a user to view a display image based on the first display image and the second display image, and an emission angle restricting means that restricts the emission angle of the second image light with respect to a display surface of the second display panel. (2) The head-mounted display according to (1), wherein the emission angle restricting means is an optical component that can reduce the amount of light emitted from the second display panel in accordance with the emission direction, and is provided on the display surface of the second display panel. (3) The head mounted display according to (1), wherein the emission angle restricting means has a function of reducing the amount of emitted light in accordance with the emission direction, and the second display panel has the emission angle restricting means built in. (4) The head mounted display according to (1), wherein the second display panel is a liquid crystal panel, and the emission angle restricting means is a film capable of changing the alignment of liquid crystal molecules of the liquid crystal panel, and is provided on the display surface of the second display panel. (5) The head mounted display according to any of (1) to (4), wherein the emission angle restricting means has a function of changing the alignment of liquid crystal molecules, and the second display panel is a liquid crystal panel with the emission angle restricting means built in. (6) The head mounted display according to any of (1) to (5), wherein the emission angle restricting means is a film including a plurality of transmissive portions and a plurality of light-blocking portions, the transmissive portions and the light-blocking portions being arranged alternately, and is provided on the display surface of the second display panel. (7) The head-mounted display according to any one of (1) to (6), wherein the second display panel is arranged so that the inclination angle of the display surface with respect to a plane perpendicular to the optical axis of the eyepiece is greater than 90°.(8) A head-mounted display described in any one of (1) to (7), wherein the first display panel is arranged so that the inclination angle of the display surface with respect to the optical mirror is less than 45°, the second display panel is arranged so that the inclination angle of the display surface with respect to the optical mirror is less than 45°, and the second display panel is arranged so that the inclination angle of the display surface with respect to a plane perpendicular to the optical axis of the eyepiece is greater than 90°.

[0035] 1 Head-mounted display, 10 First display panel, 20 Second display panel, 30 Optical mirror, 40 Eyepiece lens.

Claims

1. A head-mounted display comprising: a first display panel that displays a first display image at a first resolution; a second display panel that displays a second display image at a second resolution higher than the first resolution; an optical mirror that transmits at least a portion of the first image light emitted from the first display panel and reflects at least a portion of the second image light emitted from the second display panel; an eyepiece that receives the first image light that has transmitted through the optical mirror and the second image light that has been reflected by the optical mirror, and that allows a user to view a display image based on the first display image and the second display image; and an emission angle restriction means that restricts the emission angle of the second image light with respect to the display surface of the second display panel.

2. The head-mounted display according to claim 1, wherein the emission angle control means is an optical component that can reduce the amount of light emitted from the second display panel depending on the emission direction, and is provided on the display surface of the second display panel.

3. The head mounted display according to claim 1, wherein the emission angle restricting means has a function of reducing the amount of emitted light depending on the emission direction, and the second display panel has the emission angle restricting means built in.

4. A head-mounted display as described in claim 1, wherein the second display panel is a liquid crystal panel, and the emission angle control means is a film that can change the arrangement of liquid crystal molecules in the liquid crystal panel and is provided on the display surface of the second display panel.

5. The head mounted display according to claim 1, wherein the emission angle restricting means has a function of changing the arrangement of liquid crystal molecules, and the second display panel is a liquid crystal panel incorporating the emission angle restricting means.

6. The head-mounted display according to claim 1, wherein the emission angle restricting means is a film including a plurality of transmissive sections and a plurality of shading sections, the transmissive sections and the shading sections being arranged alternately, and the film is provided on the display surface of the second display panel.

7. A head-mounted display according to any one of claims 1 to 6, wherein the second display panel is positioned so that the inclination angle of the display surface with respect to a plane perpendicular to the optical axis of the eyepiece is greater than 90°.

8. A head mounted display according to any one of claims 1 to 6, wherein the first display panel is positioned so that the inclination angle of the display surface relative to the optical mirror is less than 45°, and the second display panel is positioned so that the inclination angle of the display surface relative to the optical mirror is less than 45°.

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