JPWO2019044501A1 - Head mounted display - Google Patents

Abstract

Provided is a head mounted display that realizes sharp image display while lowering the visibility of a black matrix. The head-mounted display includes a display panel, an enlargement optical system for enlarging an image displayed on the display panel, and a microlens array arranged in an optical path between the display panel and the enlargement optical system. The microlens array is configured by arranging a plurality of concave lenses, and is arranged with the concave surface of the concave lens facing the magnifying optical system.

Description

  The present invention relates to a head mounted display.

  The head mounted display is a display that displays an image at a close distance to the user's eyeball. Examples of the head mounted display include a goggle type disclosed in Patent Document 1 and an eyeglass type disclosed in Patent Document 2. In any case, the head mounted display employs an optical lens having a high curvature in order to display an image with a wide viewing angle in front of the user's eyes.

  As described above, in a head mounted display using an optical lens having a high curvature in order to display an image having a wide viewing angle in front of the eyes, since the pixels of the display panel appear to be enlarged, a black matrix (pixel grid) between the pixels is conspicuous. As a result, there is a problem that the pixels are visually recognized as a row of dots and the image quality is reduced.

  As a method for suppressing the deterioration of the image quality, Patent Document 3 proposes to provide an optical element such as a microlens array between the display panel and the eyepiece, which acts as an optical low-pass filter.

JP 2011-145607 A JP-A-11-346336 JP 2016-139112 A

  FIG. 8 is a diagram showing the internal configuration of the head mounted display of Patent Document 3, in which a microlens array 230 is provided on the optical path from the display panel 200 to the eyepiece 210. Patent Document 3 discloses that the image is blurred by the low-pass filter effect of the microlens array 230, that is, the effect of diffusing light, so that the black matrix of the display panel can be made inconspicuous.

  As shown in FIG. 9, a red pixel 212 </ b> R, a green pixel 212 </ b> G, and a blue pixel 212 </ b> B (hereinafter, collectively referred to as “pixel 212”) are arranged on the display panel 200, and between these pixels 212. Has a black matrix 214. When a general convex microlens array 230 as shown in FIG. 8 is arranged so that the convex surface is on the eyepiece side, in order to obtain a diffusion effect, as shown in FIG. It is necessary to use a light beam that spreads after being once converged. However, such rays are likely to be diffused to neighboring pixels and further diffused beyond neighboring pixels. Specifically, the light ray 240 incident on the microlens array 230 from the red pixel 212R and output from the convex surface 232 and refracted travels to the adjacent green pixel 212G side. In addition, the light ray 242 that enters the microlens array 230 from the green pixel 212G and is output from the convex surface 232 and refracted proceeds to the adjacent red pixel 212R side. As described above, the light output from each pixel 212 is largely refracted by the convex surface 232 and travels, and leaks to the adjacent pixel side beyond the black matrix 214. Therefore, an effect of making the black matrix inconspicuous is obtained. Has a problem that the sharpness of the image is reduced and the image is totally blurred.

  In view of the above circumstances, it is an object of the present invention to provide a head mounted display that realizes sharp image display while lowering the visibility of a black matrix.

The head mounted display of the present invention includes a display panel,
An enlargement optical system for enlarging an image displayed on the display panel,
Comprising a microlens array arranged in the optical path between the display panel and the magnifying optical system,
The microlens array is formed by arranging a plurality of concave lenses, and the concave surface of the concave lens is arranged to face the magnifying optical system.

  In the head mounted display of the present invention, it is preferable that the microlens array is arranged in contact with the image display surface of the display panel.

  The head mounted display of the present invention preferably has an antireflection function on the concave surface.

  The antireflection function can be realized by a moth-eye structure provided on the concave surface or a dielectric multilayer film.

  The head mounted display of the present invention includes a microlens array in an optical path between a display panel and an enlargement optical system for enlarging an image displayed on the display panel, and the microlens array includes a plurality of concave lenses. The concave lens is arranged with the concave surface facing the magnifying optical system. With this configuration, the visibility of the black matrix can be reduced, and a sharp image display can be realized.

FIG. 2 is a diagram of the configuration of the head mounted display according to the first embodiment as viewed from above. FIG. 2 is a diagram for describing an internal configuration of the head mounted display of FIG. 1. FIG. 9 is a diagram for explaining an effect of the concave microlens array. It is sectional drawing of a concave micro lens array. It is sectional drawing of a concave micro lens array. It is a perspective view showing the schematic structure of the head mount display of a 2nd embodiment. FIG. 7 is a diagram for explaining an internal configuration of the head mounted display of FIG. 6. FIG. 9 is a diagram for explaining an internal configuration of a conventional head mounted display. It is a figure for explaining light diffusion by the micro lens array which consists of a convex lens.

  Hereinafter, embodiments of a head mounted display of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a head mounted display (HMD: Head Mount Display) 1 according to the first embodiment as viewed from above. FIG. 1 shows a goggle-shaped main body 2 and its internal configuration. In addition to the above, various contacts such as a head contact portion and a head contact portion (not shown) for improving the wearability of the wearer on the head. It has a part.

  The HMD 1 includes a display panel 10 provided in front of the front of the eye, eyepieces 20 arranged at assumed positions of left and right pupils, and a microlens array (MLA: Micro) arranged in an optical path from the display panel 10 to the eyepiece 20. Lens Allay) 30. In the present embodiment, the eyepiece 20 constitutes an enlargement optical system that enlarges an image on the display panel 10. The MLA 30 includes a plurality of concave lenses arranged. Hereinafter, it is referred to as a concave MLA 30. The concave MLA 30 is arranged such that the concave surface 32 of the concave lens is on the eyepiece lens 20 side.

FIG. 2 is a diagram for describing an internal configuration of the HMD 1.
The display panel 10 is desirably a lightweight and high-definition panel such as a liquid crystal panel or an organic EL panel. The concave MLA 30 is arranged such that the concave surface 32 is on the eyepiece lens 20 side, and light from the display panel 10 passes through the concave MLA 30 and is emitted from the concave surface 32 to the eyepiece lens 20 side.

  The concave MLA 30 may be provided in the optical path between the display panel 10 and the magnifying optical system (here, the eyepiece 20). However, from the viewpoint of suppressing color mixing with adjacent pixels, the concave MLA 30 is close to the display panel 10 or Preferably, they are arranged in contact. Here, the image display surface of the display panel 10 is preferably arranged on the eyepiece 20 side of the display panel 10, and the concave MLA 30 is preferably arranged in contact with the image display surface of the display panel 10. As a configuration in which the concave MLA 30 is arranged in contact with the image display surface of the display panel 10, the concave MLA 30 may be attached to the image display surface via an adhesive layer, or may not be provided with an adhesive layer in a contact state. It may be held. Further, the concave MLA 30 may be incorporated into the display panel at the stage of manufacturing the display panel, and the display panel and the microlens array may be integrated.

  The HMD 1 is configured so that the user's eye 220 observes an image displayed on the display panel 10 via the eyepiece 20 and the concave MLA 30. Although the display panel 10 of the HMD is small, the display panel 10 is magnified and observed by the eyepiece 20, so that the user looks as if there is a large display in front of the eyes. In a state where the concave MLA 30 is not provided, the black matrix between the pixels of the display panel 10 becomes conspicuous due to the enlargement effect of the eyepiece 20, and the dot arrangement is emphasized and visually recognized. However, the HMD 1 of the present embodiment includes the concave MLA 30, and the light diffusion effect of the concave MLA 30 makes the black matrix of the display panel 10 inconspicuous.

FIG. 3 is a diagram for explaining the light diffusion effect by the concave MLA 30.
As shown in FIG. 3, the display panel 10 includes red pixels 12R, green pixels 12G, and blue pixels 12B. In the following, when pixels are collectively referred to without distinction of colors, they are simply referred to as “pixels 12”. A black matrix 14 exists between the pixels 12 of the display panel 10. As described above, in a state where the concave MLA 30 is not provided, when the arrangement of the pixels 12 is observed by enlarging with the eyepiece lens 20, the black matrix 14 is conspicuous, so that the pixels 12 are visually recognized as the arrangement of dots.

On the other hand, when the concave MLA 30 is provided, the light 40 from each pixel 12 spreads due to the action of the concave lens (see FIG. 3), and light between adjacent pixels is mixed between pixel boundaries, and the black matrix 14 between adjacent pixels is mixed. Blurred and inconspicuous. Further, since the bending in the diffusion direction is gentler than that of the convex lens, it is possible to reduce the color mixture with the adjacent pixels. Thereby, the sharpness of the image can be maintained. In addition, since the concave lens essentially has a light diffusion function, an effect for reducing a black matrix between pixels can be easily obtained. Therefore, if the concave MLA is used, the effect of reducing the black matrix can be sufficiently obtained even if the concave surface is a curved surface having a small curvature. When the curvature is small (that is, the radius of curvature is large), the height of the unevenness of the lens surface, that is, the height difference between the concave portion and the convex portion becomes small. The concave MLA is manufactured by transferring the shape from a mold. However, when the height of the unevenness is small, there is an advantage that the transfer is easy and the lens accuracy can be improved.
In the case where light rays are diffused using a convex lens, as described above, the light rays have to take an optical path to be diffused after being once converged, so that the optical design is likely to be restricted. On the other hand, if the lens is a concave lens, light is naturally diffused, so that there is little restriction on the optical design. Therefore, when manufacturing an MLA and designing an optical path in an HMD combined with another optical member, the concave MLA has a higher degree of freedom in design than the convex MLA and is advantageous.

Note that FIG. 3 shows the concave MLA 30 in which the pitch of the pixels 12 and the pitch of the concave surface 32 are approximately 1: 1. However, the pitch of the concave surface 32 in the concave MLA 30 does not always match the pixel 12 pitch. Is also good. The pitch of the concave surfaces 32 may be smaller than the pixel pitch so that a plurality of concave surfaces 32 correspond to one pixel. The pitch, size, etc. of the concave surface may be appropriately determined according to the pixel pitch.
The pitch and curvature of the concave surface may be appropriately set so that the effect of removing the black matrix and suppressing color mixture (realizing a sharp image) by the concave MLA 30 is optimal.

  As the shape of the concave surface of the concave lens in the concave MLA 30, the radius of curvature of the concave lens is preferably 1.5 times or more, more preferably 2 times or more, and more preferably 2.5 times or more of the lens pitch. More preferred. For example, when one pixel is 60 μm × 60 μm (R / G / B pitch is 20 μm), the lens pitch of the concave MLA is preferably about 20 μm, and the radius of curvature of the concave surface of the concave lens is preferably 50 μm or more. Here, the R / G / B pitch is the pitch of the pixels 12 described above.

  The concave surface 32 of the concave MLA 30 preferably has an antireflection function (antireflection layer). By providing the concave surface 32 with an anti-reflection function (anti-reflection layer), it is possible to suppress the reflection of the light incident on the concave MLA 30 from the display panel on the concave surface 32, and as a result, it is possible to suppress the multiple reflection in the concave MLA 30. By repeating multiple reflections in the concave MLA 30, output light from a certain pixel is emitted from an adjacent pixel or a region of a pixel farther from the adjacent pixel, and color mixing may occur. That is, by suppressing multiple reflections, the occurrence of color mixing can be effectively suppressed, and a sharper image can be displayed.

FIG. 4 and FIG. 5 are cross-sectional views of the concave MLA 30 having the antireflection function (antireflection layer) on the concave surface 32.
The concave MLA 30 shown in FIG. 4 has a moth-eye structure 34 formed on a concave surface 32. The moth-eye structure 34 is a fine uneven structure as shown in FIG. 4 and has a function of preventing reflection. The moth-eye structure 34 may be formed by processing the concave surface 32 itself, or may be formed of a separate material on the surface of the concave surface 32. By forming a thin film containing aluminum such as aluminum, alumina, or aluminum nitride on the surface of the concave surface 32 and immersing the thin film in warm water (for example, 80 ° C. or higher), a fine uneven structure made of boehmite can be formed. This concave-convex structure made of boehmite can be provided on the concave surface 32 as a moth-eye structure 34. Alternatively, using the boehmite as an etching mask, the surface of the concave surface 32 is etched by performing a reactive ion etching process from the boehmite surface side, thereby forming a fine uneven structure corresponding to the fine uneven structure of boehmite on the concave surface 32. Can be. By performing the fine unevenness on the concave surface 32 in this manner, a fine uneven structure having higher durability than boehmite can be obtained.

  The concave MLA 30 shown in FIG. 5 has an antireflection film 36 formed on the concave surface 32. The antireflection film 36 can be composed of a low refractive index layer having a refractive index smaller than that of the concave MLA 30. As the antireflection film 36, a plurality of low-refractive-index layers having a relatively low refractive index and high-refractive-index layers having a relatively high refractive index, each having a higher antireflection function, are alternately laminated. It is preferable to provide a dielectric multilayer film.

  As described above, the configuration having the antireflection function provided on the concave surface 32 of the MLA 30 may be either a moth-eye structure or an antireflection film. The use of the method for producing boehmite as described above is preferable because it can very easily achieve a configuration exhibiting uniform antireflection performance.

  The head mounted display of the present invention is not limited to the goggle type as shown in FIG. 1, but may be an eyeglass type. FIG. 6 is a perspective view showing the appearance of the head mounted display according to the second embodiment of the present invention. FIG. 7 is a diagram showing the internal configuration of the head mounted display shown in FIG.

  The head-mounted display 101 according to the second embodiment shown in FIG. 6 is a glasses-type head-mounted display. The HMD 101 of the present embodiment superimposes a display image 140 on an image of the outside world in a part of the field of view on eyeglasses provided with an eyeglass frame 102, an eyeglass vine 104 connected to the eyeglass frame 102, and an eyeglass lens 106 fitted into the eyeglass frame. And a display unit 108 for performing display. In the head-mounted display 101 of the present embodiment, a control signal of a moving image or a still image projected as a display image 140 passes through an optical fiber 109 drawn out from the rear end of the vine 104 of the spectacles to separately provide image information. Supplied from transmission means.

As shown in FIG. 7, the display unit 108 includes a display panel 110, a refractive lens 120, and a flat half mirror 122.
An image (original image) transmitted via the optical fiber 109 is displayed on the display panel 110. The refractive lens 120 has a function of enlarging an original image on the screen of the display panel 110 and projecting the enlarged image on the eye 220 of the wearer. This refraction lens 120 constitutes a magnifying optical system. The flat plate half mirror 122 has a function of reflecting image light from the refraction lens 120 toward the eye 220 and transmitting light from an external image in the optical path from the refraction lens 120 to the eye. .

  In addition, a concave MLA 30 is provided between the display panel 110 of the display unit 108 and the refractive lens 120 as the magnifying optical system.

  An image of the outside world, as if a virtual image (display image) 140 of the original image displayed on the display panel 110 magnified by the refraction lens 120 is in front of a part of the field of view of the wearer's eye 220 from the glasses. And it is projected again. By providing the concave MLA 30, the visibility of the black matrix of the display panel 110 can be reduced, and the wearer can visually recognize a sharp image as the virtual image 140 with almost no visibility of the black matrix. The operation and effect of the concave MLA 30 are the same as those of the HMD 1 of the first embodiment. The concave MLA 30 is the same as that of the first embodiment in that it is more preferable to use the concave MLA 30 having the anti-radiation function described with reference to FIG. 4 or FIG.

As described above, in each of the head-mounted displays according to the first and second embodiments, sharp image display can be realized while lowering the visibility of the black matrix of the display panel.
Note that, in the head mounted display of the present invention, the configurations and arrangements of the display panel and the magnifying optical system are not limited to the configurations of the above embodiment. As the magnifying optical system, for example, a configuration including a reflecting mirror such as a concave mirror may be used. Further, the magnifying optical system may be composed of one component, or may be composed of a combination of a plurality of optical components.

DESCRIPTION OF SYMBOLS 1, 101 Head mounted display 2 Main body part 7 Refractive lens 10 Display panel 12 Pixel 12B Blue pixel 12G Green pixel 12R Red pixel 14 Black matrix 20 Eyepiece 30 Micro lens array of concave lens 32 Concave surface 34 Moss eye structure 36 Anti-reflection film 40 Light ray 102 Eyeglass frame 104 vine 106 eyeglass lens 108 display unit 109 optical fiber 110 display panel 120 refractive lens 122 flat plate half mirror 140 display image (virtual image)
200 display panel 210 eyepiece 212 pixel 212B blue pixel 212G green pixel 212R red pixel 214 black matrix 220 eye 230 convex lens micro lens array 232 convex surface 240, 242 rays

Claims (5)

A display panel,
An enlargement optical system for enlarging an image displayed on the display panel,
A microlens array disposed in an optical path between the display panel and the magnifying optical system,
A head-mounted display in which the microlens array includes a plurality of concave lenses arranged, and a concave surface of the concave lenses is arranged to face the magnifying optical system.   The head mounted display according to claim 1, wherein the microlens array is arranged in contact with an image display surface of the display panel.   3. The head mounted display according to claim 1, wherein the concave surface has an anti-reflection function.   The head mounted display according to claim 3, wherein a moth-eye structure is provided on the concave surface. The head mounted display according to claim 3, wherein an anti-reflection film is provided on the concave surface.