JP2013044896A - Head-mounted display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmission type head-mounted display which enables a user to view a desired image even in the case that a physical distance from a lens to eyes of the user cannot be set to an optical distance.SOLUTION: A head-mounted display (HMD) 1 enables a user to view an image by guiding light of the image displayed on a liquid crystal display part 103, to a pupil 84 of a left eye 83 of the user by a lens 112 and a half mirror 8. A physical distance ERm on an optical axis from the lens 112 to the pupil 84 of the user through the half mirror 8 satisfies relation (A/tan(θ/2))<ERm<(A+(r+ω)/2)/tan(θ/2)) where A is a distance between a center axis of light passing a center part of the lens 112 and a center axis of light passing an edge part of the lens 112, ω is a width of the light, r is a diameter of the pupil 84, and θ is a field angle.

Description

  The present invention relates to an optical transmission type head mounted display.

  An optical transmission type head mounted display (HMD) is known. The optically transmissive HMD allows a user to recognize a desired image by superimposing a desired image on a scene in front of the user. In the optical transmission type HMD, it is necessary to guide light from the user's eyes directly to the user's eyes, so the HMD main body cannot be placed in front of the user's eyes. The reason is that when the HMD main body is arranged in front of the user's eyes, light from the user's front is shielded by the HMD main body. On the other hand, Patent Document 1 discloses an optical system that guides light of a desired image to the user's eye, specifically, a holding member that holds a small eyepiece in the lateral direction from the front of the user's eye. There has been proposed an optically transmissive HMD that prevents the light from the user's eyes from being blocked by the arrangement.

  Usually, in order to make the user clearly see from the center of the desired image to the peripheral portion, in the HMD, the physical distance from the lens from which light of the desired image is emitted to the user's eyes is a predetermined distance (hereinafter, Also called optical distance.). The predetermined distance is, for example, that when light of a desired image is emitted to the user's eye through a lens, all light is imaged on the user's retina regardless of the direction of the emitted light. It is a possible distance. The optical distance can be calculated based on the lens diameter and the angle of view.

JP 2006-3879 A

  However, as described in Patent Document 1, when an optical transmission type HMD optical system is disposed laterally from the front of the user's eye, the optical system is arranged so that the optical system does not enter the user's field of view. Must be placed away from the eyes. Of course, even when the optical transmission type HMD optical system is arranged vertically or obliquely from the front of the user's eyes, the optical system is also arranged so that the optical system does not enter the user's field of view. Must be placed away from There are also restrictions on the arrangement of lenses and the like constituting the optical system. For these reasons, there is a problem in that the physical distance from the lens from which light is emitted to the user's eyes cannot be set to the optical distance.

  An object of the present invention is an optically transmissive head that allows a user to visually recognize a desired image even when the physical distance from the lens to the user's eyes cannot be set to an optical distance. To provide a mount display.

The head-mounted display according to the present invention is an optically transmissive head-mounted display, which forms an image to be visually recognized by the user, and uses the light of the image formed in the image forming unit as a pupil of the user. A lens that is arranged so that an optical axis direction intersects the front-rear direction of the user in a state in which the user wears the head-mounted display, and in front of the user's eyes And a reflecting member that guides the light of the image to the pupil of the user by reflecting the light of the image that has passed through the lens, and from the lens through the reflecting member of the user ERm is a physical distance that is a physical distance on the optical axis to the pupil, ω is a width in a direction perpendicular to the optical axis in the light of the image that has passed through the lens, and A pupil diameter r, an angle of view θ, a central axis corresponding to the central portion of the image light passing through the center of the lens, and a central portion of the image light passing through the edge of the lens When the distance from the central axis corresponding to is A,
(A / tan (θ / 2)) <ERm
And ERm <(A + (r + ω) / 2) / tan (θ / 2))
It is characterized by satisfying the relationship.

  According to the present invention, when the physical distance ERm is set to a value in the above range, the head mounted display can be arranged away from the user's eyes and the light of the image formed on the image forming unit can be disposed. At least a portion can be imaged onto the user's retina. Accordingly, it is possible to prevent the head mount from blocking light from the user's eyes, to allow the user to visually recognize the scenery in front of the eyes, and to allow the user to visually recognize a desired image.

  In the present invention, the physical distance of the image formed at the edge of the image forming unit with respect to the amount of light when the user visually recognizes the light of the image formed at the center of the image forming unit. It may be determined based on the ratio of the amount of light when the user visually recognizes the light. Thus, the physical distance can be determined so that the user can visually recognize the edge of the image formed on the image forming unit with a sufficient amount of light. In addition, it is possible to design the head mounted display by determining the optimum physical distance according to the amount of light according to the application when the user uses the head mounted display.

  In the present invention, the head mounted display is attached to a mounting tool mounted on the user's head, and the reflective member is attached to the mounting tool in a state where the head mounted display is mounted on the mounting tool. A transparent member between the lens and the user, and the physical distance is the light from the lens to the reflective member, the reflective member to the transparent member, and the transparent member to the user's pupil It may be the sum of physical distances on the axis. As a result, even when a head-mounted display is attached to a wearing tool worn by the user, the desired image is visible to the user while preventing the head mount from blocking the light from the user's eyes. Can be made.

  In the present invention, the lens may be arranged at a position where the lens does not contact the user's face in a state where the user wears the head mounted display. Accordingly, it is possible to prevent the lens from coming into contact with the user's face while the user is wearing the head mounted display. For this reason, the user can comfortably use the head mounted display.

  In the present invention, the lens may be disposed at a position where the lens does not contact the mounting tool in a state where the head mounted display is attached to the mounting tool. Thereby, it is possible to prevent the head mounted display from damaging the mounting tool while the head mounted display is attached to the mounting tool.

  In the present invention, the angle of view may be specified by a radius of the lens and an eye relief length of the lens. As a result, the angle of view can be specified uniformly and the physical distance can be accurately calculated.

It is a front view of HMD1. 3 is a plan view of the HMD 1 and the glasses-type frame 91. FIG. It is the II sectional view taken on the line in FIG. It is a perspective view at the time of seeing the projection unit 10 from the upper side. It is a figure for demonstrating physical distance ERm. It is a figure for demonstrating physical distance ERm. It is a figure for demonstrating physical distance ERm. It is a figure for demonstrating physical distance ERm. It is a figure for demonstrating physical distance ERm. It is a figure for demonstrating physical distance ERm. It is a figure for demonstrating physical distance ERm. It is a table | surface which shows various parameters. It is a figure which shows the light quantity calculated by simulation. It is a graph which shows the relationship between physical distance ERm and light quantity ratio.

  Hereinafter, a head mounted display (HMD) 1 according to an embodiment of the present invention will be described with reference to the drawings. In the following description, the front direction, the depth direction, the left direction, the right direction, the upper direction, and the lower direction in FIG. 1 are the front direction, the rear direction, the left direction, the right direction, the upper direction, and the lower direction of the HMD 1, respectively.

  An outline of the HMD 1 will be described. The display format of the HMD 1 is an optical transmission type. The scenery light in front of the user's eyes is directly guided to the user's eyes by passing through the half mirror 8 (see FIG. 1, described later). The projection format of HMD1 is a virtual image projection type. The light of the image displayed on the liquid crystal device 101 (see FIG. 3, described later) provided in the HMD 1 is guided to the user's eyes by reflecting the half mirror 8. With these, the HMD 1 can make the user recognize the created image by superimposing the created image on the scenery in front of the eyes.

  As shown in FIGS. 1 and 2, the HMD 1 includes a housing 2. The housing | casing 2 is attached to the spectacles type flame | frame 91 so that attachment or detachment is possible. The glasses-type frame 91 is attached to the user's head. The eyeglass-type frame 91 includes a left frame portion 92 (see FIG. 2), a right frame portion 93, a central frame portion 94, and an HMD support portion 96. The left frame part 92 is hung on the left ear of the user. The right frame portion 93 is hung on the user's right ear. The center frame portion 94 is provided between the front end portion of the left frame portion 92 and the front end portion of the right frame portion 93. The central frame portion 94 includes a spectacle lens 81 on the left side and the lower side from the central portion in the longitudinal direction. The central frame portion 94 includes a spectacle lens 82 on the right side and the lower side from the central portion in the longitudinal direction. The spectacle lenses 81 and 82 are transparent flat plates having a diopter value of “0”. The spectacle lenses 81 and 82 are provided to prevent the housing 2 from coming into contact with the user's face when an impact is applied to the housing 2. Of course, the spectacle lenses 81 and 82 may have a predetermined diopter value according to the visual acuity of the user. The center frame portion 94 includes a pair of nose pads 95 at the center in the longitudinal direction. The HMD support part 96 is provided on the upper right end side (left end side when viewed from the user side) of the central frame part 94. The HMD support portion 96 includes a downward extending portion 98 (see FIG. 1). The downward extending portion 98 extends in the vertical direction.

  A held portion (not shown) is provided on the surface of the housing 2 that faces the eyeglass-type frame 91. The held portion includes a U-shaped groove along the vertical direction. A downward extending portion 98 is fitted in the U-shaped groove. Since the friction member is provided at the bottom of the U-shaped groove, the HMD 1 can be positioned in the vertical direction.

  The housing 2 of the HMD 1 will be described. The housing 2 has a rectangular tube shape. The case 2 protrudes in the vertical direction from the substantially right and left center to the right end. The material of the housing 2 is resin. The housing 2 includes a mirror holder 5, a left housing 11, a middle housing 12, and a right housing 13 in order from the left side to the right side.

  The mirror holder 5 is fixed to the left end of the left housing 11. The mirror holder 5 includes a pair of upper and lower sandwich plates 6 and 7 (see FIG. 1). The sandwich plates 6 and 7 hold the half mirror 8 from above and below. The half mirror 8 swings around the part held by the sandwiching plates 6 and 7. The user can adjust the angle of the half mirror 8 according to the position of the eye.

  The left housing 11 and the middle housing 12 are cylindrical bodies that extend in the left-right direction, respectively. The left casing 11 and the middle casing 12 are fixed on the same axis in a state in which opposite end portions are in contact with each other. The upper surface of the left housing 11 is inclined one step upward from the center in the left-right direction and obliquely upward to the right. The lower surface of the left housing 11 is inclined one step downward from the center in the left-right direction obliquely downward to the right. A notch-shaped slit portion 9 </ b> A is provided on the front surface and the right end side of the left housing 11. The slit portion 9A exposes a part of the adjuster 16 to the outside. The adjuster 16 can be rotated up and down. The user can adjust the focus of the visually recognized image by rotating the adjuster 16. The right housing 13 is a lid-like cover member. The right housing 13 is fixed so as to close the right end side where the middle housing 12 opens.

  The interior of the housing 2 will be described with reference to FIG. The projection unit 10 is stored in the left casing 11 and the middle casing 12. A control board 20 that electrically controls the projection unit 10 is stored in the right housing 13.

  The projection unit 10 will be described. The projection unit 10 includes a lens holder 15, a liquid crystal holder 17, and a liquid crystal device 101 in order from the left side to the right side. The lens holder 15 is substantially cylindrical. The lens holder 15 holds the eyepiece optical system 102 from the substantially right and left center to the left side inside the cylindrical shape. The right side portion of the lens holder 15 from the substantially right and left center is hollow. The eyepiece optical system 102 includes a plurality of lenses 111. The optical axes of the plurality of lenses 111 are arranged on an axis extending in the left-right direction at the center of the cylindrical interior. The plurality of lenses 111 are arranged in the left-right direction and are fixed to the lens holder 15. Among the plurality of lenses 111, the lens fixed to the leftmost side of the lens holder 15, that is, the lens closest to the user's eye is referred to as a lens 112. The radius of the lens 112 is the largest among the plurality of lenses 111.

  The liquid crystal holder 17 includes a cylindrical peripheral wall portion 171. A right wall portion 172 that closes the opening is provided at the right end of the peripheral wall portion 171. An opening window 173 is provided at the center of the right wall 172. The liquid crystal device 101 is held on the right surface of the right wall portion 172. The liquid crystal device 101 includes a liquid crystal display unit 103 at the center of the left surface. The liquid crystal display unit 103 displays an image that is superimposed on the scenery in front of the user.

  As shown in FIG. 4, the optical axes 115 of the plurality of lenses 111 extend in the left-right direction. The optical axes 115 of the plurality of lenses 111 are orthogonal to the user's front-rear direction (vertical direction in FIG. 4). The half mirror 8 is disposed in front of the left eye 83 of the user. The projection unit 10 is provided on the right side (left side when viewed from the user) with respect to the front of the user's left eye 83 so that the housing 2 (see FIGS. 1 to 3) does not enter the user's field of view as much as possible. It has been. Further, the housing 2 is fixed at a position spaced forward from the eyeglass-type frame 91 so that the housing 2 of the HMD 1 does not contact the eyeglass lens 82. Therefore, the projection unit 10 is disposed at a position spaced forward from the eyeglass-type frame 91. The direction of the optical axis 115 of the plurality of lenses 111 fixed to the lens holder 15 of the projection unit 10 is limited to the left-right direction. The lens 112 is the largest among the plurality of lenses 111. For this reason, the front and rear end portions of the lens 112 are projected most in the front-rear direction among the plurality of lenses 111. For this reason, at least the distance Y from the front end of the spectacle lens 82 to the optical axis 115 of the lens 112 is larger than the radius of the lens 112 so that the housing 2 does not contact the spectacle lens 82. As described above, it is necessary to adjust the position of the housing 2 with respect to the glasses-type frame 91. This prevents the housing 2 from coming into contact with the spectacle lens 82 and damaging the spectacle lens 82.

  The light of the image displayed on the liquid crystal display unit 103 passes through the opening window 173 (see FIG. 3) to the left, travels leftward inside the cylindrical shape of the lens holder 15, and includes a plurality of lenses 111 including the lens 112. To reach the half mirror 8. The half mirror 8 reflects the light of the image toward the rear (the user side). The reflected image light passes through the spectacle lens 82 from the front to the rear, and enters the pupil 84 of the left eye 83 of the user. The light that has entered the pupil 84 forms an image on the retina.

A physical distance on the optical axis from the lens 112 to the pupil 84 of the left eye 83 of the user via the half mirror 8 (hereinafter referred to as a physical distance) is expressed by the following formula (1). Can do. However, the physical distance is ERm, the physical distance on the optical axis from the left surface of the lens 112 to the half mirror 8 is X, and the physical distance on the optical axis from the half mirror 8 to the front surface of the spectacle lens 82 is Y. The physical distance on the optical axis from the front surface of the spectacle lens 82 to the center of the pupil 84 of the left eye 83 of the user in the front-rear direction is represented as Z.
ERm = X + Y + Z (1)

  At the same time, the scenery light in front of the user passes through the half mirror 8 from the front to the rear. The scenery light that has passed through the half mirror 8 further passes through the spectacle lens 82 and enters the pupil 84 of the left eye 83 of the user. The light that has entered the pupil 84 forms an image on the retina. As a result, the user can view both images simultaneously with the image created by the HMD 1 superimposed on the scene in front of him.

  In order for the image light to enter the pupil 84 and form an image on the retina, the value of the physical distance ERm needs to be within a predetermined range. The possible range of the physical distance ERm will be described with reference to FIGS. 5 to 11, the half mirror 8 is omitted for ease of explanation. In addition, among the plurality of lenses 111, only the lens 112 closest to the user's left eye 83 is shown. Accordingly, in FIGS. 5 to 11, the light of the image displayed on the liquid crystal display unit 103 passes through the lens 112 and enters the pupil 84 of the left eye 83 as it is. The physical distance ERm shown in FIGS. 5 to 11 is equal to the physical distance ERm in the actual system (see FIGS. 1 to 4) via the half mirror 8. 5 to 7, the width ω in the direction orthogonal to the optical axis of the light is equal to the diameter r of the pupil 84 when the light of the image displayed at one point of the liquid crystal display unit 103 passes through the lens 112. Assume the case. 8 and 9 assume the case where the width ω is larger than the diameter r. 10 and 11 assume the case where the width ω is smaller than the diameter r.

  FIG. 5 shows a state in which the pupil 84 of the left eye 83 of the user is arranged at the eye point by the plurality of lenses 111. In this case, the light 71 at the center of the image displayed on the liquid crystal display unit 103 passes through the center of the lens 112 and enters the pupil 84. The light 71 incident on the pupil 84 forms an image at a point 72 on the retina. Further, the light 73 at the edge of the image displayed on the liquid crystal display unit 103 passes through the edge of the lens 112 and enters the pupil 84. The light 73 that has entered the pupil 84 forms an image at a point 74 on the retina. The user can visually recognize both the central portion of the image displayed on the liquid crystal display unit 103 and the edge portion of the image displayed on the liquid crystal display unit 103. Hereinafter, the image displayed on the liquid crystal display unit 103 is also referred to as a display image.

An angle formed by the optical axis and the light 73 (hereinafter referred to as an incident angle) satisfies the relationship of the following formula (2). However, the incident angle is α, the center axis of the light 71 passing through the center of the lens 112, that is, the distance between the optical axis and the center axis of the light 73 passing through the edge of the lens 112 is A, and the eye relief of the lens 112 The length is represented as L.
tan α = A / L (2)
The angle of view of the display image and the incident angle α indicate the relationship of the following expression (3). However, the angle of view is represented as θ.
θ = 2 × α (3)
Equation (4) is derived from Equations (2) and (3).
tan (θ / 2) = A / L
L = A / tan (θ / 2) (4)
As is clear from the expressions (2), (3), and (4), the angle of view θ is uniquely specified by the eye relief length L and the distance A of the lens 111. Here, the radius of the lens is a value obtained by adding the distance A to the half of the width ω of the light 71 and 73 (ω / 2) in order to use the light without omission. Hereinafter, the radius of the lens 112 is expressed as D (= A + ω / 2). Therefore, the angle of view θ is specified by the radius D of the lens 112 and the eye relief length of the lens 111.

  In order to make the edge portion of the display image visible to the same extent as the center portion of the display image, the physical distance ERm needs to be the same as the eye relief length L shown in Expression (4). Hereinafter, the eye relief length L expressed by the equation (4) is also referred to as an optical distance. The optical distance is also expressed as ER0. However, in practice, as shown in FIG. 4, the physical distance ERm is obtained by the sum of X, Y, and Z. Among these parameters, Z (physical distance on the optical axis from the front surface of the spectacle lens 82 to the center in the front-rear direction of the pupil 84 of the left eye 83 of the user) is a predetermined value (about 20 mm) in known spectacles. It is defined as. Further, Y (physical distance on the optical axis from the half mirror 8 to the front surface of the spectacle lens 82) is made larger than the radius of the lens 112 in order to prevent the housing 2 from coming into contact with the spectacle lens 82. There is a need. Furthermore, X (physical distance on the optical axis from the left surface of the lens 112 to the half mirror 8) needs to be as large as possible so that the housing 2 does not enter the user's field of view as much as possible. Due to the above constraints, at least the values of X and Y tend to be large, so the physical distance ERm is larger than the value satisfying the relationship of Expression (4), that is, the optical distance ER0.

The case where the physical distance ERm is larger by ΔER than the state of FIG. 5 will be described with reference to FIG. The physical distance ERm satisfies the relationship of the following formula (6).
ERm = ER0 + ΔER
= A / tan (θ / 2) + ΔER (6)
When the light 73 at the edge of the display image is incident on the pupil 84 of the left eye 83 via the lens 112, this corresponds to the width t of the width ω of the display image 73 passing through the center side of the lens 112. The light 75 does not enter the pupil 84 of the left eye 83. In this case, the angle of view θ and the width t satisfy the relationship of the following formula (7).
t = ΔER × tan (θ / 2) (7)
Therefore, as ΔER increases, the width t increases, so that the amount of light incident on the pupil 84 in the light 73 gradually decreases. For this reason, the light quantity of the display image when the user visually recognizes the edge portion of the display image decreases as the physical distance ERm increases as ΔER increases. The edge portion of the display image visually recognized by the user gradually becomes dark as the physical distance ERm increases.

As shown in FIG. 7, it is assumed that the physical distance ERm is further larger than the state of FIG. ΔER increases, and the width t of light 75 not incident on the pupil 84 is equal to the width ω. In this case, the light 73 at the edge of the display image does not enter the pupil 84 of the left eye 83 at all. In this case, the angle of view θ and the width ω are in a state satisfying the relationship of the following formula (8).
ω = ΔER × tan (θ / 2) (8)
In this case, the user cannot visually recognize the edge portion of the display image. Therefore, ΔER needs to be smaller than ω / tan (θ / 2) in order for the user to visually recognize the edge portion of the display image. Therefore, the upper limit that the physical distance ERm can take needs to satisfy the relationship of the following equation (9-1) in relation to the equation (6).
ERm <A / tan (θ / 2) + (ω / tan (θ / 2))
= (A + ω) / tan (θ / 2) (9-1)
Now, since it is assumed that the width ω of the lights 71 and 73 is equal to the diameter r of the pupil 84, ω can also be expressed as (r + ω) / 2. As a result, Formula (9-1) can also be expressed as the following Formula (9-2).
ERm <(A + (r + ω) / 2) / tan (θ / 2) (9-2)

Based on Expression (4), the lower limit value of ERm is set to be greater than the optical distance ER0 (= A / tan (θ / 2)). As a result, the range that the physical distance ERm can take in the case where the pupil diameter r is equal to the width ω of the lights 71 and 73 is expressed by the following equation (10).
A / tan (θ / 2) <ERm <(A + (r + ω) / 2) / tan (θ / 2) (10)

  A case where the width ω of the light 71 and 73 is larger than the diameter r of the pupil 84 will be described with reference to FIGS. 8 and 9. FIG. 8 shows a state in which the pupil 84 of the left eye 83 of the user is arranged at an eye point by a plurality of lenses 111 (see FIGS. 3 and 4). Since the width ω of the light 71 and 73 of the display image is larger than the diameter r of the pupil 84, the light 71 and 73 protrudes from the pupil 84 up and down by (ω−r) / 2.

In FIG. 9, as the physical distance ERm increases as ΔER increases, the light 73 at the edge of the display image does not enter the pupil 84 of the left eye 83 at all. In this case, the angle of view θ and the width ω are obtained by subtracting the width (ω−r) / 2 (see FIG. 8) of the light protruding from the pupil 84 from the left side of the equation (8) (11) )
ω− (ω−r) / 2 = ΔER × tan (θ / 2) (11)
In order for the user to visually recognize the edge portion of the display image, ΔER needs to be smaller than (ω− (ω−r) / 2) / tan (θ / 2). Therefore, the upper limit value that the physical distance ERm can take needs to satisfy the relationship of the following equation (12) in relation to the equation (6).
ERm <A / tan (θ / 2) + ((ω− (ω−r) / 2) / tan (θ / 2))
= (A + (r + ω) / 2) / tan (θ / 2) (12)

Based on Expression (4), the lower limit value of ERm is set to be greater than the optical distance ER0 (= A / tan (θ / 2)). As a result, the range that the physical distance ERm can take when the width ω of the light 71 and 73 is larger than the diameter r of the pupil is expressed by the following equation (13).
A / tan (θ / 2) <ERm <(A + (r + ω) / 2) / tan (θ / 2) (13)

  Expression (13) has the same notation as Expression (9-2), but the upper limit value of Expression (13) is larger than the upper limit value of Expression (9-2). This is because when the width ω of the lights 71 and 73 is larger than the diameter r of the pupil, the value of ω becomes larger than when the width ω of the lights 71 and 73 is equal to the diameter r of the pupil. It is assumed that the pupil diameter r is constant.

  A case where the width ω of the light 71 and 73 is smaller than the diameter r of the pupil 84 will be described with reference to FIGS. 10 and 11. FIG. 10 shows a state in which the pupil 84 of the left eye 83 of the user is arranged at an eye point by a plurality of lenses 111 (see FIGS. 3 and 4). Since the width ω of the light 71 and 73 of the display image is smaller than the diameter r of the pupil 84, the light 71 and 73 enter the inside of the pupil 84 by each of the upper and lower (r−ω) / 2.

In FIG. 11, as the physical distance ERm increases as ΔER increases, the light 73 at the edge of the display image does not enter the pupil 84 of the left eye 83 at all. In this case, the angle of view θ and the width ω are obtained by adding the width (r−ω) / 2 (see FIG. 10) of the light that has entered the inside of the pupil 84 to the left side of the equation (8). The relationship of (14) is satisfied.
ω + (r−ω) / 2 = ΔER × tan (θ / 2) (14)
In order for the user to visually recognize the edge portion of the display image, ΔER needs to be smaller than (ω + (r−ω) / 2) / tan (θ / 2). Therefore, the upper limit value that the physical distance ERm can take needs to satisfy the relationship of the following equation (15) in relation to the equation (6).
ERm <A / tan (θ / 2) + ((ω + (r−ω) / 2) / tan (θ / 2))
= (A + (r + ω) / 2) / tan (θ / 2) (15)

Based on Expression (4), the lower limit value of ERm is set to be greater than the optical distance ER0 (= A / tan (θ / 2)). As a result, the range that the physical distance ERm can take when the width ω of the light 71 and 73 is smaller than the diameter r of the pupil is expressed by the following equation (16).
A / tan (θ / 2) <ERm <(A + (r + ω) / 2) / tan (θ / 2) (16)

  Expression (16) has the same notation as Expression (9-2), but the upper limit value of Expression (16) is smaller than the upper limit value of Expression (9-2). This is because the value of ω is smaller when the width ω of the light 71 and 73 is smaller than the diameter r of the pupil than when the width ω of the light 71 and 73 is equal to the diameter r of the pupil. It is assumed that the pupil diameter r is constant.

  As described above, by setting ERm to a value within the range indicated by Equation (9-2), Equation (13), and Equation (16), the housing 2 of the HMD 1 is separated from the user's eyes. At least part of the light of the image that is arranged and displayed on the liquid crystal display unit 103 can be imaged on the retina of the user. As a result, the housing 2 is prevented from blocking the light from the front of the user so that the user can visually recognize the scenery in front of the user, and the edge of the display image displayed on the liquid crystal display unit 103 is used. Can be visually recognized.

  Further, since the physical distance ERm can be made larger than the optical distance ER0, Y in FIG. 4 (physical distance on the optical axis from the spectacle lens 82 to the half mirror 8) and X (half mirror 8). The physical distance on the optical axis from the lens 112 to the lens 112 can be increased. Therefore, it is possible to prevent the housing 2 from coming into contact with the spectacle lens 82 by increasing the value of Y. Further, by increasing the value of X, it is possible to prevent the housing 2 from entering the user's field of view as much as possible.

  The liquid crystal display unit 103 corresponds to the “image forming unit” of the present invention. The half mirror 8 corresponds to the “reflecting member” of the present invention. The eyeglass-type frame 91 corresponds to the “wear” of the present invention. The spectacle lenses 81 and 82 correspond to the “transparent member” of the present invention.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. The housing 2 of the HMD 1 may be provided in a direction other than the front side to the right side (left side as viewed from the user) of the left eye 83 of the user, for example, the left side, the upper and lower sides, and the oblique side. The direction in which the optical axes 115 (see FIG. 4) of the plurality of lenses 111 extend is not limited to the left-right direction. Moreover, the optical axis 115 and the user's front-back direction should just cross | intersect, and do not need to be orthogonally crossed. The glasses-type frame 91 may be well-known glasses, or goggles for protecting eyes. A prism may be used instead of the half mirror 8. Instead of displaying an image on the liquid crystal display unit 103, laser light may be emitted toward the pupil 84 of the user. The user may make the user visually recognize the image by scanning with laser light.

  In the HMD 1, the physical distance Y on the optical axis from the half mirror 8 to the front surface of the spectacle lens 82 is at least larger than the radius of the lens 112. On the other hand, when the central frame portion 91 of the spectacle-shaped frame 91 protrudes forward from the spectacle lens 82, the physical frame on the optical axis from the half mirror 8 to the front surface of the central frame portion 91 is physical. The distance may be at least larger than the radius of the lens 112.

The HMD 1 may be directly attached to the user's head. In this case, the physical distance on the optical axis from the left surface of the lens 112 to the half mirror 8 is x, and the physical distance on the optical axis from the half mirror 8 to the center in the front-rear direction of the pupil 84 of the left eye 83 of the user. When the distance is expressed as z, the physical distance ERm satisfies the relationship of the following formula (17).
ERm = x + z (17)
In this case, at least the z (physical distance on the optical axis from the half mirror 8 to the center of the pupil 84 of the left eye 83 of the user in the front-rear direction) is larger than the radius of the lens 112. It is necessary to adjust the position of the housing 2 with respect to. Thereby, it can suppress that the housing | casing 2 contacts a user or gives a user discomfort.

  An embodiment of the present invention will be described with reference to FIGS. In the experimental example, when the physical distance ERm of the HMD 1 is changed, the following evaluation was performed in order to verify how the display image is visually recognized by the user and to identify an appropriate physical distance ERm. .

  The amount of light of the image passing through the user's pupil 84 was analyzed by simulation. Optical distance ER0, incident angle θ / 2, X (see FIG. 4), Y (see FIG. 4), Z (see FIG. 4), radius D of lens 112, diameter r of pupil 84, and light width ω The values (see FIGS. 5 to 11) were set as shown in FIG. In addition, when the above-mentioned formula (13) was applied under this condition, the range of the physical distance ERm was 30 mm <ERm <53 mm.

  The area of light in a circular pattern when the physical distance ERm was set to the optical distance ER0 was used as a reference. Then, the ratio between the light area of the circular pattern and the reference light area when the physical distance ERm is larger than the optical distance ER0 was calculated as the light amount ratio. And the relationship between ERm and light quantity ratio was evaluated. In addition, when the light amount ratio is 25% or more, it is visually recognized well by the user. Therefore, the range of the physical distance ERm when the light amount ratio is 25% or more is specified.

  FIG. 13 shows the amount of light of the image passing through the pupil 84, obtained for each light amount ERm. In FIG. 13, 1 to 10 show the pupil 84 when ΔER is set to 0, 3, 6, 9, 10, 11, 12, 13, 14, and 15 by changing D, respectively. Shows light passing through. As is clear from FIG. 13, the circular pattern gradually decreased as the physical distance ERm increased.

  FIG. 14 shows a graph representing the relationship between the physical distance ERm (unit: mm) and the light amount ratio (unit:%). From this result, it was found that the light quantity ratio was 25% or more under the condition that ERm was 43 mm or less. Accordingly, the HMD 1 has a physical distance ERm of 30 mm <ERm <53 mm (upper limit value calculated based on the formula (13)), more preferably a range of 30 mm <ERm <43 mm (based on simulation, a light quantity ratio of 25% or more). It is found that the user can visually recognize the image displayed on the liquid crystal display unit 103 by setting the upper limit value satisfying the above condition.

2 Housing 8 Half mirror 10 Projection unit 81, 82 Eyeglass lens 83 Left eye 84 Pupil 91 Eyeglass type frame 101 Liquid crystal device 103 Liquid crystal display unit 112 Lens

Claims (6)

An optically transmissive head-mounted display,
An image forming unit for forming an image to be visually recognized by a user;
A lens for guiding light of the image formed in the image forming unit to a pupil of a user, the optical axis direction being in the front-rear direction of the user when the user is wearing the head mounted display; A lens arranged to intersect with the
A reflecting member that is disposed in front of the user's eyes and guides the light of the image to the pupil of the user by reflecting the light of the image that has passed through the lens;
ERm is a physical distance on the optical axis from the lens to the pupil of the user via the reflecting member, and is orthogonal to the optical axis in the light of the image that has passed through the lens. The width of the direction is ω, the diameter of the pupil of the user is r, the angle of view is θ, and the central axis corresponding to the central portion of the light of the image passing through the center of the lens and the edge of the lens When the distance from the central axis corresponding to the central portion of the light of the image is A,
(A / tan (θ / 2)) <ERm
And ERm <(A + (r + ω) / 2) / tan (θ / 2))
A head-mounted display characterized by satisfying the above relationship. The physical distance is
When the user visually recognizes the light of the image formed at the edge of the image forming portion with respect to the amount of light when the user visually recognizes the light of the image formed at the center of the image forming portion. The head-mounted display according to claim 1, wherein the head-mounted display is determined based on a light amount ratio. The head mounted display is attached to a wearing tool to be worn on the user's head,
The wearing tool is provided with a transparent member between the reflective member and the user in a state where the head mounted display is attached to the wearing tool.
The physical distance is
2. The total of physical distances on the optical axis from the lens to the reflecting member, from the reflecting member to the transparent member, and from the transparent member to the user's pupil. 2. The head mounted display according to 2. The lens is
The head mounted display according to claim 1 or 2, wherein the lens is disposed at a position where the lens does not contact the user's face in a state where the user mounts the head mounted display. The lens is
The head mounted display according to claim 3, wherein the head mounted display is disposed at a position where the lens does not contact the mounting tool in a state where the head mounted display is mounted on the mounting tool. The angle of view is
6. The head mounted display according to claim 1, wherein the head mounted display is specified by a radius of the lens and an eye relief length of the lens.