JP7665364B2 - Angle-selective transmission element and display device - Google Patents

Description

The present invention relates to ghost reduction technology for head-mounted displays, binoculars, camera viewfinders, etc., and in particular to an angle-selectable transmission element that is attached to the viewfinder.

When a user uses a head-mounted display or a camera viewfinder outdoors, there is a possibility that light coming from behind the user may cause ghosting. In order to reduce unnecessary light caused by external light, Patent Document 1 discloses a technology that cuts out the light that causes ghosting by placing a louver film on the eye side of the display unit.

Japanese Patent Application Publication No. 5-215908

In the conventional technology disclosed in Patent Document 1, light is cut in the light-shielding direction of a louver film placed on the display unit. Therefore, this method cannot be applied to applications where the user brings their eye close to the display, such as viewfinders, because vignetting occurs on the periphery.
An object of the present invention is to provide an angle-selective transmission element that enables ocular observation without vignetting at the periphery while reducing ghosts caused by external light.

An optical element according to an embodiment of the present invention is an angle-selective transmission element disposed in an optical path and having a plurality of openings, characterized in that it has a limiting means constituted by the plurality of openings and limits the passing direction of a light beam, the light beam passing portion in the limiting means is formed radially from a point that is three-dimensionally predetermined as a center, and the inside of the openings is filled with a substance having a refractive index difference with respect to air of 0.1 or less.

The present invention provides an angle-selectable transmission element that reduces ghosting caused by external light and allows ocular observation without vignetting at the periphery.

1 is an external view of a display device (head mounted display) to which the present invention is applied. FIG. 2 is a diagram showing a state in which a user wears the display device on his/her head. 3 is a diagram showing a state in which the display unit is flipped up from the state shown in FIG. 2; FIG. FIG. 2 is a cross-sectional view showing a configuration of the display device during use. 3 is a cross-sectional view taken along line AA in FIG. 2. FIG. 6 is a detailed view showing part B in FIG. 5 . FIG. 2 is a diagram showing a first surface side of an angle-selective transmission element. FIG. 2 is a diagram showing a second surface side of the angle-selective transmission element. FIG. 8 is a detailed view showing part C in FIG. 7 . 8 is a cross-sectional view taken along line DD in FIG. 7. FIG. 9 is a detailed view showing part E in FIG. 8 . 1A and 1B are diagrams illustrating examples of the shape of an opening portion provided in an angle-selective transmission element. 13 is a diagram showing a second surface side of an angle-selective transmission element according to a modified example. FIG. FIG. 6 is a cross-sectional view showing an optical path different from that in FIG. 5 in a modified example. FIG. 15 is a detailed view showing part G in FIG. 14 . 13A and 13B are detailed diagrams illustrating an angle-selective transmission element according to a modified example. FIG. 6 is a cross-sectional view showing an optical path different from that in FIG. 5 in a modified example. FIG. 18 is a detailed view showing part H in FIG. 17 . FIG. 11 is an external view illustrating a second embodiment of the present invention. FIG. 20 is an exploded perspective view showing the configuration of the angle-selective transmission element of FIG. 19 . FIG. 2 is a detailed view showing the wall of the angle-selective transmission element with metal plates laminated thereon. 1 is a diagram illustrating the relationship between an opening of an angle-selective transmission element and an eye point. 23 is a diagram for explaining the relationship between the state in which the eye point position is moved and the amount of opening enlargement in comparison with FIG. 22. FIG. FIG. 11 is a configuration diagram for explaining a third embodiment of the present invention. FIG. 25 is a plan view showing an example of the arrangement of the film in FIG. 24. FIG. 13 is an external view illustrating a fourth embodiment of the present invention. FIG. 27 is a partial cross-sectional view of the angle-selective transmission element of FIG. 26.

Below, an embodiment of the present invention will be described in detail with reference to the drawings. A head mounted display (hereinafter, referred to as HMD) is shown as an example of a display device that uses an angle-selective transmission element arranged in the optical path of a viewfinder, etc. Note that the present invention is not limited to this, and can be applied to various optical devices.

[First embodiment]
An angle-selective transmission element according to a first embodiment of the present invention will be described with reference to Fig. 1 to Fig. 11. Fig. 1 is an external view showing a configuration example of an HMD 1. The HMD 1 comprises a main body 2, electronic viewfinders (hereinafter referred to as EVFs) 3 and 4, and a head-mounted unit 5. The pair of EVFs comprises an EVF 3 for the left eye and an EVF 4 for the right eye.

The main body 2 and head-mounted part 5 of the HMD 1 are rotatably connected by a hinge 2a on the main body 2 side and a hinge 5a on the head-mounted part 5 side. The left-eye EVF 3 and right-eye EVF 4 are held relative to the main body 2 in a state in which the interpupillary distance can be adjusted.

Figures 2 and 3 show the state in which a user wears the HMD 1 on the head. Figure 2 shows the state in which the user is looking at the display screen, and Figure 3 shows the state in which the main body 2 of the HMD 1 is flipped up so that the user can see the surroundings.

Angle-selective transmission elements 6 and 7 are attached to the areas where the user looks into EVF 3 and EVF 4, respectively. In this embodiment, angle-selective transmission element 6 and angle-selective transmission element 7 have the same configuration, but by making the configuration of both elements different, it is possible to optimize the convergence angle between the right eye and the left eye and the ghost cutting characteristics.

Figure 4 is a cross-sectional view showing the configuration of the main body 2 and EVF 3 when the HMD 1 is in use, showing the portion corresponding to the left eye of the user. The display unit 9 and eyepiece lens system 10 are provided inside the exterior member 11 of the EVF 3. The display unit 9 has an organic EL (Electro-Luminescence) display panel. The surface of the eyepiece lens system 10 facing the angle-selective transmission element 6 is flat. The angle-selective transmission element 6 is disposed in a position facing the user's left eye on the exterior member 11. The first surface 6a of the angle-selective transmission element 6 is the surface facing the user's eye, and the second surface 6b is the surface facing the eyepiece lens system 10.

The angle-selective transmission element 6 is provided with a plurality of openings 6c, which have the function of restricting the light passing direction. The plurality of openings 6c constitute a restricting means for restricting the passing direction of the light beam in the angle-selective transmission element arranged in the optical path. The light beam passing portion is formed three-dimensionally (spatially) radially from a predetermined point. The predetermined point is a point on the optical axis away from the angle-selective transmission element 6. For example, the plurality of openings 6c are opened in the direction of the light beam from the eyepiece lens system 10 toward the position of the eye point 13, which is the position of the user's eye. Figure 4 shows a schematic diagram of the finder light beam 12 that reaches the eye point 13 out of the light beams emitted from the eyepiece lens system 10. The position of the eye point 13 is determined by the eyepiece lens system 10.

The exterior member 14 of the main body 2 has a control circuit 15 inside that controls the entire HMD 1. The control circuit 15 controls the display unit 9, and light from the display unit 9 is collected by the eyepiece lens system 10 and passes through multiple openings 6c provided in the angle-selective transmission element 6, allowing the information displayed on the display unit 9 to be observed by the eye at the eye point 13.

Figure 5 is a cross-sectional view taken along line A-A in Figure 2, and shows the relationship between the head and eyeballs and the HMD 1 when the HMD 1 is in use. Figure 6 is a detailed view showing an enlarged view of part B in Figure 5. Part B in Figure 5 shows a portion facing the left eye of the user. As shown in Figure 6, the multiple openings 6c inside the angle-selective transmission element 6 are formed between multiple adjacent walls 6d. In other words, two adjacent openings 6c are separated by a wall 6d.

In this embodiment, the inside of the multiple openings 6c is filled with a transparent solid that has a small refractive index difference with air. By filling the inside of the angle-selective transmission element 6 with a transparent solid that has a small refractive index difference with air, it is possible to prevent dust from entering the multiple openings 6c. In addition, it is possible to prevent the wall portion 6d from being deformed by an external force. In this embodiment, a porous transparent material containing 90% or more of air is used as the transparent solid that has a small refractive index difference with air, and the refractive index difference with air is 0.1 or less. Therefore, there is almost no reflection at the boundary surface with air. Inside the multiple openings 6c, there is almost no reflection at the transparent solid surface that has a small refractive index difference with air on both the first surface 6a on the eye side and the second surface 6b on the eyepiece lens system 10 side, and light that enters the multiple openings 6c from the outside enters the inside with almost no reflection.

Anti-reflection treatment is applied to the first surface 6a, the second surface 6b, and the inner surfaces of the multiple openings 6c (the inner surfaces of the wall portion 6d) of the angle-selective transmission element 6. The angle-selective transmission element 6 can be created using a 3D printer, and the anti-reflection treatment can be achieved by applying an anti-reflection coating.

When using the HMD1 shown in Figure 5, assume that the light is completely in front of the user, that is, the light is coming from a direction in which the user faces away from the light source (such as the sun). In this case, most of the light that enters the angle-selective transmission element 6 and eyepiece lens system 10 is blocked by the user's head. However, if the user rotates their face from this state to the side by an angle of several tens of degrees, the light that passes through the side of the face (light that passes through the cross-hatched area in Figure 5) reaches the position of the angle-selective transmission element 6 and eyepiece lens system 10.

In the case of the left eye, the area where reverse light may cause ghosts in the eyepiece lens system 10 is the cross-hatched area in FIG. 5, as shown by the line 17 connecting point 16 in FIG. 5 and the side of the head. In this embodiment, multiple openings 6c are provided from the eye point 13 toward the eyepiece lens system 10. In order for light to reach the eyepiece lens system 10, which is located away from the multiple openings 6c, a light source must be present in the direction of the hole in the openings 6c. Line 17 in FIG. 5 indicates the position where the direction of the multiple openings 6c and the direction of the light are closest, making it easier for reverse light to reach the eyepiece lens system 10.

In Figure 6, light ray 18 represents light that has passed through the side of the user's head. Light ray 18 enters the inside through holes in the multiple openings 6c provided on the first surface 6a of the angle-selective transmission element 6. The light that enters the multiple openings 6c reaches the wall 6d, but because the wall 6d is treated with an anti-reflection coating, the reflected light is attenuated. Therefore, even if the reflected light reaches the eyepiece lens system 10, almost no ghosting occurs.

The thickness of the angle-selective transmission element 6 is denoted as t, the opening width of the opening 6c is denoted as w, and the incident angle of the unwanted light is denoted as θ _0. The condition for preventing the unwanted light from directly reaching the eyepiece lens system 10 is shown in the following formula (1).
t≧w/tanθ ₀ (1)
Tan represents a tangent function, and in this embodiment, the condition of formula (1) is satisfied.

Figure 7 is a schematic diagram showing the first surface 6a of the angle-selective transmission element 6. Figure 8 is a schematic diagram showing the second surface 6b of the angle-selective transmission element 6. Figure 9 is a detailed enlarged view of part C in Figure 7. Figure 10 is a cross-sectional view taken along line D-D in Figure 7. Figure 11 is a detailed enlarged view of part E in Figure 8.

As shown in Figures 7 to 9, the multiple openings 6c provided in the angle-selective transmission element 6 are formed in a hexagonal shape on the second surface 6b, which is the entrance side of the viewfinder light rays, and on the first surface 6a, which is the exit side of the viewfinder light rays. In this embodiment, all of the hexagonal openings provided on the second surface 6b have the same shape within the second surface 6b. Also, all of the hexagonal openings provided on the first surface 6a have the same shape within the first surface 6a. Adjacent hexagonal portions are separated by walls 6d, and the inside of the openings 6c is filled with a transparent solid that has a small refractive index difference with air.

Figure 10 (a cross-sectional view taken along line D-D of Figure 7) shows the orientation of the multiple openings 6c. The orientation of the multiple openings 6c is set so that it is aligned with the direction of light heading toward the eye point 13. In other words, the multiple openings 6c are formed three-dimensionally, radially from the eye point 13, which is a predetermined point, as the center. The distance between the eye point 13 and the first surface 6a is denoted as E1, and the distance between the eye point 13 and the second surface 6b is denoted as E2. The formation pitch of the multiple openings 6c on the first surface 6a is denoted as P1.

The multiple openings 6c are provided at equal pitches, and the distance from the center of the optical axis is represented as Hi. In the right half of FIG. 10 with the center of the optical axis as the reference, i in "Hi" represents any natural number from 1 to 9.
H1=P1
H2 = P1 x 2
・
・
H8 = P1 x 8
H9 = P1 x 9
In other words, the relationship is "Hi = P1 x i."

With respect to the center of the optical axis as a reference, the angle of each line connecting the eye point 13 and each of the apertures 6c is represented as θi, where i represents any natural number from 1 to 9.
θ1=tan ^-1 (H1/E1)
θ2=tan ^-1 (H2/E1)
・
・
θ8=tan ^-1 (H8/E1)
θ9=tan ^-1 (H9/E1)
Tan ⁻¹ represents the arctangent function, and the relationship is “θi=tan ⁻¹ (Hi/E1)”.

The pitch P2 of the multiple openings 6c on the second surface 6b is as shown in the following formula (2).
P2=E2×tanθ1 (2)
In FIG. 10, the right half surface has been described with reference to the center of the optical axis, but the same relationship as above also applies to the left half surface since the configuration is symmetrical with respect to the optical axis.

When the eyepiece lens system 10 is viewed from the user's eye with the position of the eyepoint 13 as a reference, the eyepiece lens system 10 is seen through the multiple openings 6c. The wall 6d is almost parallel to the direction of light reaching the user's eye, so it is almost invisible. Also, when the user's eye is at the eyepoint 13, the first surface 6a is close to the eye and the focus is not correct. The wall 6d is made thin, so the flat surface at the entrance of the wall 6d is almost invisible. Also, as shown in Figures 9 and 11, in this embodiment, the thickness of the wall 6d between the openings is formed to be equal on the eye side and the lens side.

The user can only view the displayed information from the vicinity of eyepoint 13, and the position of the eyes must be fixed near eyepoint 13. In this embodiment, the head mounting unit 5 fixes the relative positional relationship between the user's head and the HMD 1, thereby enabling the eyes to be placed at the position of eyepoint 13.

In this embodiment, the angle-selective transmission element 6 arranged in the optical path of the viewfinder has multiple openings 6c that limit the passing direction of the light beam to a predetermined range. The angle range in which the passing direction of the viewfinder light is limited is different in at least two regions (see FIG. 10). In other words, the first angle (lens optical axis direction angle) that limits the passing direction at the center position as the first region for the viewfinder light beam is different from the second angle (θ1) that limits the passing direction at the peripheral position as the second region for the light beam. The light passing direction limiting means is composed of multiple openings 6c that radiate from the eye point 13 toward the eyepiece lens system 10. In addition, in this embodiment, ten types of light passing directions are provided, including eight regions θ2 to θ9. Therefore, it is possible to limit or block light from directions other than the eye point.

This embodiment provides an angle-selectable transmission element that reduces ghosting caused by external light from behind the user while allowing ocular observation without vignetting at the edges.

[Modification of the first embodiment]
Modifications of the first embodiment will be described with reference to Fig. 12 to Fig. 18. Fig. 12 is a diagram showing the shape of the openings 6c provided on the first surface 6a and the second surface 6b of the angle-selective transmission element 6. Fig. 12(A) shows a case where the multiple openings 6c provided on the first surface 6a and the second surface 6b of the angle-selective transmission element 6 are formed in a regular hexagonal shape, as described in the first embodiment. In this case, the aperture ratio is the largest, and the structure has the highest flexibility (shock absorption capacity).

In the modified example, examples of the shape of the opening 6c will be described. In addition to the regular hexagon, regular polygons that can fill a plane with one type also include the equilateral triangle shown in FIG. 12(B) and the regular quadrilateral (square) shown in FIG. 12(C). These three types of shapes are called regular plane fillings. Of these, the equilateral triangle has the greatest strength, and the shape of the opening 6c can be selected depending on the application.

The multiple openings 6c provided on the first surface 6a and the second surface 6b of the angle-selective transmission element 6 can be composed of multiple regular polygons only. These are called Archimedean tessellations, which have uniform vertex shapes that can fill a plane, and there are eight different shapes. Among them, there are two types that combine equilateral triangles and regular hexagons. Figures 12(D) and 12(E) show examples of combinations of equilateral triangles and regular hexagons. By using a configuration using multiple regular polygons, the angle-selective transmission element 6 can be created by combining the advantages of each shape. Other shapes that can be used for plane tessellation include polygonal plane tessellation, non-periodic tessellation, and tessellation with a center (spiral tessellation, radial tessellation, etc.). These can also be applied to the shape of the openings 6c depending on the application.

Figure 13 shows a modified example having multiple regions with different apertures. Figure 13(A) shows the second surface 6b of the angle-selective transmission element 6, and Figure 13(B) is a detailed view of part F in Figure 13(A). This shows a configuration in which the aperture of the angle-selective transmission element 6 is partially modified. By mixing the wide aperture portion 6c and the narrow aperture portion 6f, it becomes easier to achieve both an improvement in the aperture ratio and a reduction in unnecessary light.

With reference to Figures 14 and 15, the light passing through the side of the user's head will be described. Figure 14 is a cross-sectional view showing a different optical path from that of Figure 5, and Figure 15 is a detailed view of part G in Figure 14. Light ray 55 in Figure 14 and light rays 55a, 55b, and 55c in Figure 15 represent light that has passed through the side of the user's head. Light that enters the multiple openings 6c is reflected by wall 6d, but the number of reflections decreases as it approaches the center of the head. Therefore, if the reflected light is not sufficiently attenuated, the light that causes ghosts cannot be uniformly reduced.

A detailed diagram of the modified example is shown in Figure 16. Figure 16 shows the light path when the opening 6f is placed toward the center of the head. The opening of the opening 6f in the area toward the center of the user's eyes is narrower than the opening in the area away from the center of the eyes. In the modified example, narrowing the opening increases the number of times the light rays are reflected, making them more likely to be attenuated. Also, because the opening 6c with a wide opening is placed in the center of the angle-selective transmission element 6, the view through the eyepiece lens system 10 is not impaired.

Instead of narrowing the opening, there is a method of partially changing the material thickness of the angle-selective transmission element 6. With reference to Figures 17 and 18, the light passing through the side of the user's head will be described. Figure 17 is a cross-sectional view showing a different optical path from Figure 5, and Figure 18 is a detailed view of part H in Figure 17. The light rays 55, 55a, 55b, and 55c are as described in Figures 14 and 15. The tubular length of the opening in the area toward the center of the user's eyes is longer than the tubular length of the opening in the area away from the center of the eyes.

In the modified example shown in Figures 17 and 18, the surface 6g on the entrance side of the viewfinder light beam of the angle-selective transmission element 6 is formed in a curved shape that follows the curved surface of the eyepiece lens system 10. By increasing the tube length of the opening 6c toward the center of the user's head, the number of reflections of the light beam increases, making it easier to attenuate.

[Second embodiment]
Next, a second embodiment of the present invention will be described. In this embodiment, an example is shown in which an angle-selective transmission element is made of a laminated structure of metal plates. In this embodiment, detailed explanations of matters similar to those in the first embodiment will be omitted, and differences will be mainly explained. The method of omitting such explanations will be the same in the embodiments described later.

Figure 19 is an external view of an angle-selective transmission element 20 made by stacking multiple metal plates. The surface shown in the figure is the surface 20b on the eyepiece lens system side, and the opposite surface is the surface 20a on the eye side. The angle-selective transmission element 20 has multiple openings 20c, similar to the first embodiment.

Figure 20 is an exploded perspective view of the angle-selective transmission element 20. The angle-selective transmission element 20 is composed of 19 aluminum plates 19. The aluminum plates 19 are provided with multiple openings 20c by forming circular holes by etching. The diameter of the circular holes is the same for all 19 aluminum plates, but the pitch is different.

Figure 21 (A) is a partial cross-sectional view showing a state in which multiple aluminum plates 19 are stacked. The upper side of Figure 21 (A) is the eyepiece lens system side, and the lower side of Figure 14 is the eye side. In the stacked state, the opening 20c faces the eyepoint position as in the first embodiment. The size of the opening diameter of the multiple openings 20c provided in the aluminum plates 19 varies for each aluminum plate to be stacked, with the opening 20a on the eye side being the smallest and the opening 20b on the eyepiece lens system side being the largest. In addition, the area that limits the direction in which the light beam passes is formed by configuring the center position of the opening diameter of the openings 20c provided in the aluminum plates 19 to be different at the front and rear of the stacked aluminum plates.

In this embodiment, the opening diameter of the multiple openings 20c provided in one aluminum plate 19 is uniform, and the pitch is different for each stacked aluminum plate, so the width of the walls between the holes varies. After the metal plates are stacked, they are integrated by diffusion bonding, and then matte anodized to provide an anti-reflection treatment for the entire plate.

The multiple openings 20c that limit the direction in which the light beam passes are separated by walls 20d and are made up of walls in at least two directions that are not parallel to the direction in which the light beam passes. A detailed explanation will be given using Figure 21.

In the detailed view of the wall of the angle-selective transmission element shown in FIG. 21(A), the wall 20d is composed of wall surface 20d1 and wall surface 20d2. FIG. 21(B) is a cross-sectional view of one aluminum plate 19 of the multiple laminated aluminum plates. The opening 20c provided in the aluminum plate 19 may be provided with a sharp edge shape portion 20e. The sharp edge shape portion 20e provided in the aluminum plate 19 and the anti-reflection treatment applied to the wall 20d can increase the amount of attenuation of reflected light.

In this embodiment, glass (not shown) is placed on one side (eye side) of the angle-selective transmission element 20 to prevent dust from entering. In addition, an anti-reflection coating is applied to both surfaces of the glass. According to this embodiment, an angle-selective transmission element that achieves the same effect as the previous embodiment can be realized by using a configuration in which multiple metal plates are stacked.

As a means of realizing a form in which the hole pitch is different to match the optical path for metal plates stacked in the optical axis direction, the opening diameter of multiple openings in one metal plate is made uniform and the distance between the holes is made different. The benefits of this include making the metal plate easier to process and making it easier to block light that causes ghosts.

On the other hand, as another method for forming an aperture that matches the optical path, the aperture diameters of the multiple openings 20c are made different as described above. In this case, it is reasonable to make the aperture size larger for metal plates closer to the eyepiece system and smaller for metal plates closer to the eyepoint along the optical path where light diffusing at the exit pupil of the eyepiece system is focused on the eyepoint. In particular, it is desirable for the shape to be a cone with the eyepoint as its apex.

Figure 22 is a schematic diagram showing the relationship between the opening of an angle-selective transmission element and the eyepoint. As mentioned above, this shows an example of openings in multiple metal plates when the opening is provided as a cone with the eyepoint as its apex. Figure 22 shows an optical axis 60, an eyepiece lens 61 closest to the eye, metal plates 62a-c for blocking light, and eyepoint 63. The openings in metal plates 62a-c are provided to form a cone shape with eyepoint 63 as its apex, as shown by the dashed line.

However, in the configuration shown in FIG. 22, the eyebox, which is the visual field area in which an image can be seen properly, becomes small, and even a slight deviation of the eye position from the eyepoint can result in vignetting of the image. In such a situation, it is effective to enlarge the opening of the metal plate close to the eyepoint from a shape that follows the cone. By making the amount of opening enlargement from the cone larger for metal plates closer to the eyepoint, the effect of enlarging the eyebox can be expected. This is also true when metal plates (mask members) are placed with a gap in between, as in the fourth embodiment described below.

Figure 23 is a diagram showing the state in which the eyepoint position has been moved with respect to Figure 22. Figure 23 (A) is a diagram showing an example of an enlarged aperture area of a metal plate close to the eyepoint for enlarging the eyebox. Figure 23 (B) is an enlarged diagram showing the enlarged aperture area of interest. Point 64 is a point corresponding to the eyepoint at the end of the eyebox when the eyebox is enlarged. As shown by the dashed line, the upper line of the display area is blocked by the aperture from the eyepoint position of point 64, and vignetting occurs in the image. Therefore, by enlarging the aperture in the parts corresponding to regions 65b and 65c, it is possible to suppress the occurrence of vignetting even from the eyepoint position of point 64, and to properly observe the image. As a result, the image can be properly observed not only at point 63 but also at point 64, making it possible to enlarge the eyebox.

The amount of aperture expansion will be described with reference to FIG. 23(B). It is reasonable to expand the amount of aperture expansion in proportion to the distance between the eyepiece and the mask member (metal plate). That is, the distances from the eyepiece surface to the metal plates 62b and 62c are denoted as db and dc, respectively. Using an appropriate proportionality coefficient k, the aperture is expanded as "aperture expansion amount corresponding to region 65b = k x db" and "aperture expansion amount corresponding to region 65c = k x dc". This ensures an optical path connecting the image at the eyepiece position and the eye point (point 64) at the eye box edge position, and makes it possible to obtain a good image without vignetting even at the eye point position indicated by point 64. Note that, although FIG. 23 describes a configuration in which the amount of aperture expansion is proportional to the distance from the eyepiece surface, this is not a limitation. The openings of the openings that the multiple plates or mask members have on the eye point side may be expanded relative to the line connecting the opening of the opening of the plate or mask member closest to the eyepiece system and the eye point. By removing the areas corresponding to areas 65b and 65c in at least some of the openings in three or more plates or mask members to widen the openings, it is possible to ensure a sufficient eye box.

[Third Example]
A third embodiment of the present invention will be described with reference to Figures 24 and 25. The angle-selective transmission element of this embodiment is constructed using a plurality of types of louver films.

Figure 24 is a schematic diagram showing an example of an angle-selective transmission element that is realized by combining multiple types of louver films. The louver film has a structure in which plate-shaped opaque parts are regularly arranged inside a transparent film, making it possible to control the direction in which light passes.

As shown in Figure 24, the louver film constituting the angle-selective transmission element of this embodiment is divided into multiple regions 33-35 centered around the viewfinder optical axis. The angle of light ray 30 parallel to the viewfinder optical axis, i.e., the first angle, is defined as zero. Light ray 31 represents light at a second angle that is inclined to the viewfinder optical axis, and light ray 32 represents light at a third angle. The third angle is larger than the second angle.

In the example shown in FIG. 24, the first region 33 has an opaque portion that is parallel to the viewfinder optical axis (first angle) and extends in the depth direction of FIG. 24 (direction perpendicular to the paper surface). The second region 34 has an opaque portion that is parallel to the second angle and extends in the depth direction of FIG. 24. The third region 35 has an opaque portion that is parallel to the third angle and extends in the depth direction of FIG. 24.

Figure 25 is a diagram showing the planar arrangement of the configuration of Figure 24, and is a schematic diagram when viewed from a direction along the viewfinder optical axis. In this embodiment, the film is arranged in eight regions divided in the rotational direction around the viewfinder optical axis. The shape of the first region 33 closest to the viewfinder optical axis is a roughly regular octagon, and the second region 34 adjacent to the outside of it is composed of eight divided regions. Similarly, the third region 35 adjacent to the outside of the second region 34 is composed of eight divided regions. Each region shown in Figure 25 is arranged rotationally symmetrically around the viewfinder optical axis. Note that the division method shown in this embodiment is an example, and the number of divisions, etc. can be set arbitrarily.

According to this embodiment, an angle-selective transmission element similar to that of the previous embodiment can be constructed by combining multiple types of louver films that are created by laminating opaque and transparent films and changing the direction in which light is cut.

[Fourth embodiment]
A fourth embodiment of the present invention will be described with reference to Figures 26 and 27. In this embodiment, an example of an angle-selective transmission element having a structure in which a plurality of mask members (metal plates) are arranged at predetermined intervals will be shown.

Figure 26 shows a separate stacked angle selection type transmission element 40. The surface visible in Figure 26 is surface 40b on the eyepiece lens system side, and the opposite surface is surface 40a on the eye side. The transmission element 40 is realized by intermittently arranging multiple metal plates as described in the second embodiment.

Figure 27 is a partial cross-sectional view of the transmission element 40. The transmission element 40 is configured by overlapping multiple mask members and spacers (separation members). For example, a first spacer 50 is arranged on one side of the first mask 41. Next (on the upper side of Figure 27), a second mask 42 is positioned, and a second spacer 51 is further arranged. Similarly, a third mask 43 and a third spacer 52, a fourth mask 44 and a fourth spacer 53, a fifth mask 45 and a fifth spacer 54 are arranged, and a sixth mask 46 is further arranged. In this way, the first to fifth spacers are arranged between the first to sixth masks, respectively, forming gaps between the mask members.

In FIG. 27, the viewfinder optical axis 47 and the direction toward the eyepoint position (not shown) are indicated by dashed lines. The positions of the multiple openings of the transmission element 40 change depending on the distance from each layer indicated by the first mask 41 to the sixth mask 46 and the viewfinder optical axis 47. Taking the intermediate light beam indicated by the light ray 48 as an example, the openings 41a to 46a in FIG. 27 are arranged along the direction of the light beam. That is, the first mask 41 has an opening 41a, the second mask 42 has an opening 42a, the third mask 43 has an opening 43a, the fourth mask 44 has an opening 44a, the fifth mask 45 has an opening 45a, and the sixth mask 46 has an opening 46a. With the viewfinder optical axis 47 as a reference, the distance to the opening 41a is the shortest, and the distance to the opening 46a is the longest.

When there is a gap between adjacent mask members, there is a possibility that crosstalk light passing through the gap may reach the eyepiece lens system, which may result in ghosting. In this embodiment, measures are taken to reduce crosstalk light. An example of light that may cause ghosting is shown as light beam group 49 in FIG. 27. For example, light that passes through opening 41a of first mask 41 is blocked by connecting regions 42b, 43b, 44b, and 45b between the openings. Connecting regions 42b, 43b, 44b, and 45b are provided in second mask 42 to fifth mask 45, respectively, and the light-blocking (or light-reducing) function of each region prevents unnecessary light from reaching the eyepiece lens system.

In addition, with regard to this light blocking (or light reduction) function, the connecting regions 42b, 43b, 44b, and 45b may block the reflected light from the eyepiece lens surface without blocking the incident light as shown by the group of rays 49. In other words, even if the optical path passing through the opening 41a reaches the eyepiece lens surface, the connecting regions 42b, 43b, 44b, and 45b may block the reflected light before it exits from another opening. Compared to a configuration in which light blocking or light reduction is performed only on the incident optical path, it is possible to improve the design freedom of the connecting regions.

The transmission element 40 shown in this embodiment has glass (not shown) on one side (the side facing the user's eye) to prevent dust from entering. The glass has an anti-reflective coating on both sides.

According to this embodiment, in a configuration having multiple gaps in which separation members are disposed between multiple mask members, it is possible to realize an angle-selective transmission element that achieves the same effect as the previous embodiment.

The configuration described in the above embodiment provides an optical element and optical device that allows the user to observe the displayed information through the eyepiece while reducing ghosting caused by light coming from behind the user. In other words, even in applications (finders and HMDs) where the user's eyes are close to the optical system to within a few centimeters, the displayed information can be observed without causing peripheral vignetting. In addition, when using a finder using the angle-selective transmission element of the above embodiment, it is possible to ensure a sufficient field of view, allowing the user to grasp the surrounding situation. For example, in a method of attaching a rubber eyecup to a finder, the eyecup may become large due to the need to ensure close contact between the face and the eyepiece without any gaps. In devices that the user observes with both eyes, such as binoculars and HMDs, a large eyecup narrows the field of view and makes it difficult for the user to grasp the surrounding situation, limiting use while moving. Applying the angle-selective transmission element of the present invention to a finder is effective in solving such problems (eliminating the need for eyecups or reducing their size).

The above describes preferred embodiments of the present invention, but the present invention is not limited to these embodiments, and various modifications and variations are possible within the scope of the gist of the invention.

1 HMD (display device)
6, 7 Angle-selective transmission element 6c Aperture

Claims (23)

An angle-selective transmission element disposed in an optical path and having a plurality of apertures,
a limiting means configured by the plurality of openings and limiting a passing direction of a light beam;
an angle-selective transmission element, characterized in that the passage portion of the light beam in the limiting means is formed radially from a point that is three-dimensionally predetermined as a center, and the inside of the opening is filled with a material whose refractive index difference with air is 0.1 or less. The angle-selective transmission element according to claim 1 , wherein the light flux passing portions are formed radially from a point on the optical axis away from the angle-selective transmission element as a center. 3. The angle-selective transmission element according to claim 1, wherein a surface thereof is subjected to an anti-reflection treatment. The angle-selective transmission element according to claim 1 , wherein the first surface and the second surface having the plurality of openings in the angle-selective transmission element are configured in a regular plane tessellation shape. The angle-selective transmission element according to any one of claims 1 to 3, characterized in that the first surface and the second surface having the plurality of openings in the angle-selective transmission element are configured as Archimedean tessellations using a plurality of types of regular polygons. 6. The angle-selective transmission element according to claim 1, wherein the substance is a porous transparent substance containing 90% or more of air. The angle-selective transmission element according to claim 1 , wherein the plurality of openings are separated by walls, and the walls are subjected to an anti-reflection treatment. An angle-selective transmission element disposed in an optical path and formed by stacking a plurality of plates,
a limiting means configured by a plurality of openings in the plurality of plates and limiting a passing direction of a light beam;
an angle-selective transmission element, characterized in that the wall portion provided in the opening is composed of wall surfaces in at least two directions that are not parallel to the light passing direction, and the light beam passing portion in the limiting means is formed radially from a point that is predetermined three-dimensionally as a center. The angle-selective transmission element according to claim 8 , wherein the central positions of the aperture diameters of the openings are different between the front and rear of the laminated plates. The angle-selective transmission element according to claim 8 , wherein the openings have different opening sizes before and after the laminated plates. The angle-selective transmission element according to claim 1 , further comprising a plurality of regions each having a different opening size or a different tube length of the opening. A display device comprising the angle-selective transmission element according to claim 1 . a viewfinder having a display means and an eyepiece system;
13. The display device according to claim 12 , wherein the angle-selective transmission element is disposed at an eye point in the viewfinder, the eye point corresponding to the position of a user's eyes. 14. The display device according to claim 13 , wherein the limiting means is constituted by the plurality of openings arranged radially from the eye point toward the eyepiece lens system. 14. The display device according to claim 13 , wherein the limiting means is constituted by the plurality of openings formed in a plurality of plates along a direction from the eye point toward the eyepiece lens system. the eyepiece lens system is located between the display means and the angle-selective transmission element;
16. The display device according to claim 13 , wherein the angle-selective transmission element is located between the eyepoint and the eyepiece lens system. A display device having a display means and an eyepiece lens system, the display device comprising a plurality of viewfinders corresponding to both eyes, and a plurality of angle-selective transmission elements disposed in the viewfinders at eye points corresponding to the positions of the eyes of a user,
The angle-selective transmission element has a limiting means for limiting the passing direction of a light beam,
a display device characterized in that the limiting means has a plurality of openings, the light beam passing portion is formed radially from the eye point, has a first opening in a first region toward the center of both eyes, and has a second opening in a second region away from the center of both eyes, and the opening of the first opening is narrower than the opening of the second opening. A display device having a display means and an eyepiece lens system, the display device comprising a plurality of viewfinders corresponding to both eyes, and a plurality of angle-selective transmission elements disposed in the viewfinders at eye points corresponding to the positions of the eyes of a user,
The angle-selective transmission element has a limiting means for limiting the passing direction of a light beam,
The display device characterized in that the limiting means has a plurality of openings, the light beam passing portion is formed radially from the eye point, has a first opening in a first region toward the center of both eyes, and has a second opening in a second region away from the center of both eyes, and a tube length of the first opening is longer than a tube length of the second opening. 19. The display device according to claim 18 , wherein at least a part of the limiting means is formed along a curved surface of the eyepiece lens system. A display device comprising a finder having a display means and an eyepiece lens system, and an angle-selective transmission element disposed in an optical path,
The angle-selective transmission element is
The light source includes a limiting means configured with a plurality of openings and limiting a passing direction of a light beam;
the light beam passing portion of the limiting means is formed radially from a point that is three-dimensionally determined in advance as a center,
the angle-selective transmission element disposed at an eye point corresponding to the position of a user's eyes in the viewfinder is composed of a plurality of plates or mask members having the openings ,
A display device characterized in that the opening of the opening on the eyepoint side of the plurality of plates or mask members is enlarged with respect to a line connecting the opening of the opening of the plate or mask member closest to the eyepiece lens system and the eyepoint. The display device according to claim 20, characterized in that the amount of expansion of the opening of the opening of a second plate or mask member that is farther away from the eyepiece lens system than the first plate or mask member is greater than the amount of expansion of the opening of a first plate or mask member that is closer to the eyepiece lens system . 22. The display device according to claim 21 , wherein an amount of enlargement of the aperture is proportional to a distance between the eyepiece lens system and the plate or the mask member. 21. The display device according to claim 20 , wherein the mask member has a plurality of regions between the openings that block light passing through the openings or light reflected by a lens surface of the eyepiece lens system.

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