JP6464976B2 - Display device and head mounted display - Google Patents

Description

  The present invention relates to a display device including a liquid crystal display element, and a head-mounted display capable of mounting the display device on a user's head.

  A head mounted display (hereinafter referred to as “HMD”) including a liquid crystal display element is known. The HMD described in Patent Document 1 includes a liquid crystal unit, an eyepiece optical system, a focus adjustment mechanism (adjuster), and a half mirror. Light of an image displayed on the liquid crystal display element of the liquid crystal unit (hereinafter referred to as “image light”) enters the eyepiece optical system and exits from the eyepiece optical system toward the half mirror. The image light is bent by a half mirror and is incident on one eye of the user. Thereby, the user visually recognizes the image as a virtual image. The focus adjustment mechanism moves the eyepiece optical system in a direction along the optical axis of the eyepiece optical system. The user can focus on the virtual image by operating the focus adjustment mechanism and moving the eyepiece optical system.

JP2015-49305A

  In the above HMD, a case where a transmissive liquid crystal unit is used will be exemplified. In this case, the liquid crystal display element is generally provided with a transparent thin plate member (for example, a polarizing filter or a protective plate) on the surface thereof. When the liquid crystal display element is exposed, foreign matters such as dust are likely to adhere to the surface of the liquid crystal display element. When a foreign object adheres to the surface of the liquid crystal display element, the distance between the surface of the member on the transparent thin plate and the liquid crystal layer is short, and thus a virtual image of the foreign object may be visually recognized by the user. On the other hand, in the above HMD, a case where a reflective liquid crystal unit is used will be exemplified. In this case, the light guide member that guides light from the light source to the liquid crystal display element is often fixed in close contact with the surface of the liquid crystal display element. In this case, the adhesion of foreign matter to the surface of the liquid crystal display element is suppressed by the light guide member. Further, even when the light guide member is spaced apart and fixed to the surface of the liquid crystal display element, the light guide member and the liquid crystal display element are hermetically sealed to prevent foreign matter from entering the liquid crystal display element. Adhesion can be easily suppressed.

  When a reflective liquid crystal unit is used, foreign matter may adhere to the outer surface of the light guide member. In this case, since the position of the foreign substance is closer to the eyepiece optical system than the surface of the liquid crystal display element, it is difficult to focus on the virtual image of the foreign substance. Therefore, it becomes difficult for the user to visually recognize the foreign image of the foreign object, so that the image quality of the image may be maintained. However, for example, depending on the optical system employed in the HMD, such as the distance between the outer surface of the light guide member and the eyepiece optical system and the focal length of the eyepiece optical system, a reflective liquid crystal unit may be used. Even if it exists, a user may be able to visually recognize the virtual image of a foreign material. In this case, the image quality of the image visually recognized by the user is degraded.

  An object of the present invention is to provide a display device that has a reflective liquid crystal unit and can suppress deterioration in image quality even when foreign matter adheres to the surface of the light guide member, and the display device is mounted on the user's head It is to provide a possible head mounted display.

The display device according to the first aspect of the present invention includes a light source, a reflective liquid crystal display element capable of displaying an image, and a light that is fixed to the liquid crystal display element and guides light emitted from the light source to the liquid crystal display element. A light guide member and eyepiece optics that are provided downstream of the light guide member in the optical path of the image light emitted from the liquid crystal display element based on the light guided by the light guide member and collect the image light A system, a light source, the liquid crystal display element, the light guide member, and the eyepiece optical system, a housing that is long in a direction extending along the optical axis of the eyepiece optical system, and the eyepiece optical in the optical path A deflection member that is provided downstream of the optical system and deflects at least a part of the image light emitted from the eyepiece optical system in a specific direction intersecting a longitudinal direction of the housing , and the eyepiece optical system Is the focal length of f [mm] The distance in the optical path between the principal point of the eyepiece optical system and the virtual image of the image is b [mm], and the distance in the optical path between the liquid crystal display element and the light guide member is d [mm]. Where f, b and d are
(However, b> 0, f> 0 , d> 0) to satisfy the relationship, the case where the distance from the most downstream side in the optical path of the eyepiece optical system to the exit pupil and E [mm], wherein f , B, d and E are
(However, E> 0), where E is the third surface closest to the deflecting member of the eyepiece optical system in the longitudinal direction of the housing and the optical axis of the eyepiece optical system intersects. A first distance between three points and a fourth point where the deflecting member and the optical axis of the eyepiece optical system intersect, and a fifth point of the housing that protrudes most in the specific direction and the first point. It is larger than the total distance of the second distances in the specific direction between the four points .

  In the display device described above, in order to prevent focusing on the virtual image of the foreign matter existing on the light guide member, the virtual image of the foreign matter may be always arranged at a focus position that is difficult for the user to visually recognize. Here, it is said that the average near-point distance of eyes of people in their 20s is about 100 mm. That is, it is difficult for people in their 20s to focus their eyes on an object that is present at a position closer than about 100 mm from the eye (that is, a virtual image closer than 100 mm). For this reason, if the distance between the main point of the eyepiece optical system and the virtual image of the foreign object is smaller than 100 mm, it becomes difficult for the user to always visually recognize the virtual image of the foreign object.

On the other hand, in the display device, when f, b, and d satisfy the above relationship, the distance between the main point of the eyepiece optical system and the virtual image of the foreign object is shorter than 100 mm. In this case, it becomes difficult for the user to always visually recognize the virtual image of the foreign object. Therefore, the display device can suppress degradation of the image quality due to the presence of the foreign matter.
In the above, E corresponds to the so-called eye relief length. Therefore, when f, b, d, and E satisfy the above-described relationship, the display device is not subject to foreign objects even when the display device is mounted on the user while being spaced from the user's eyes. It can suppress visually recognizing a virtual image.
In addition, the display device can prevent the casing from coming into contact with the user while the display device is attached to the user while suppressing the user from visually recognizing the virtual image of the foreign object.

  In the first aspect, the position of the virtual image is defined as a first position having a shortest distance in the optical path between the principal point of the eyepiece optical system and the virtual image, the principal point of the eyepiece optical system, and the virtual image. A setting mechanism that can be set between the second position having the longest distance in the optical path between the first position and the second position, wherein the virtual image is positioned at a specific position between the first position and the second position. The distance in the optical path between the principal point and the virtual image may be used. When the display device has a setting mechanism, depending on the position of the virtual image of the image, the virtual image of the foreign object is presented at a position that matches the focus of the eye, and the user can visually recognize the virtual image of the foreign object There is. However, if the above relationship is satisfied with respect to b when the virtual image of the image is located at a specific position, the main point of the eyepiece optical system is obtained when the virtual image of the image is located between the specific position and the first position. The distance between the object and the virtual image of the foreign object is shorter than 100 mm. Accordingly, the virtual image of the image is ensured between the specific position and the first position so that the focus of the image can be set by the setting mechanism and the deterioration of the image quality due to the presence of the foreign matter can be suppressed. be able to.

  In the first aspect, b may be a distance in the optical path between the principal point and the virtual image when the virtual image is located at the second position. In this case, even when the virtual image of the image is set to the second position by the setting mechanism, the distance between the main point of the eyepiece optical system and the virtual image of the foreign object is shorter than 100 mm. Therefore, it is possible to suppress degradation of the image quality due to the presence of foreign matter in the entire range where the focus setting of the image by the setting mechanism is possible.

  In the first aspect, the d may be 5 mm or more. In this case, the display device can expand the range of values of f that can be adopted by the eyepiece optical system while maintaining a state in which the virtual image of the foreign object is difficult for the user to visually recognize, so that the virtual image of the foreign object is focused. Thus, the range of f where the virtual image is visually recognized can be narrowed.

  1st aspect WHEREIN: 300 mm or more and 600 mm or less may be sufficient as said b. For example, assuming a typical size of a liquid crystal display element (for example, 0.5 to 0.7 inches diagonally), in a portion where the distance between the light guide member and the liquid crystal display element is short, d is at least about It is desirable that it be 3 mm or more. Further, in order to obtain a relatively large angle of view (for example, 20 to 30 degrees diagonally), f is preferably about 21.5 mm or less. In this case, by setting b to be 300 mm or more and 600 mm or less, it is possible to suppress deterioration in image quality due to the presence of foreign matter.

  In the first aspect, the most downstream surface in the optical path of the light guide member is inclined with respect to the optical path, and the d is the most downstream surface of the light guide member and the optical axis of the eyepiece optical system. May be a distance between a first point that intersects and a second point that intersects the display surface of the liquid crystal display element and the optical axis of the eyepiece optical system. In this case, when a foreign substance adheres to the surface of the light guide member corresponding to the center position of the image, the display device can prevent the user from visually recognizing the virtual image of the foreign substance.

  A head-mounted display according to a second aspect of the present invention is a member that attaches the display device to the display device according to the first aspect and a mounting tool that is attached to a user's head, and is a predetermined movable member. And a connection device capable of moving the display device within a range, wherein the display device is moved to a position farthest from the wearing tool within the movable range. It is smaller than the distance between the wearing tool and the display device in a state. According to the second aspect, the head mounted display can prevent the user from visually recognizing the virtual image of the foreign object even when the display device is moved to any position within the movable range by the connecting tool.

It is a perspective view of HMD1 in the state where display 11 approached in front of a user's eyes. 3 is a perspective view of a display device 11. FIG. FIG. 3 is an exploded perspective view inside the display device 11. 6 is a rear view of the adjustment mechanism 4. FIG. It is a perspective view inside HMD1 in the 1st state. It is a perspective view inside HMD1 in the 2nd state. It is a figure which shows the positional relationship of the lens unit 6, the image unit 7, the foreign material virtual image 77B, the image virtual image 77C, etc. FIG. 3 is a diagram showing a positional relationship between the display device 11 and an exit pupil 21. FIG. It is a perspective view of HMD1 in the state where display 11 separated from the user's eyes. It is a grab showing the relationship between f and b (s). It is a grab showing the relationship between d and b (s). It is a grab showing the relationship between d and b (s). It is a grab showing the relationship between f and b (s) + E.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a head mounted display (hereinafter referred to as “HMD”) 1 is an optically transmissive see-through HMD. The light in the scene in front of the user's eyes is guided directly to the user's eyes by passing through the half mirror 56. The projection format of HMD1 is a virtual image projection type. The half mirror 56 reflects the light of the image displayed on the liquid crystal display element 72 </ b> C (see FIG. 3, described later) toward one eye of the user. The HMD 1 can allow the user to recognize an image superimposed on the scene in front of him. The HMD 1 includes a display device 11, a wearing tool 8, and a connecting tool 9. Hereinafter, in order to help understand the description of the figure, the upper side, lower side, left side, right side, front side, and rear side of the HMD 1 are defined. The upper side, the lower side, the left side, the right side, the front side, and the rear side of the HMD 1 correspond to, for example, the upper side, the lower side, the left side, the right side, the lower left diagonal side, and the upper right diagonal side of FIG. The upper side, the lower side, the left side, the right side, the front side, and the rear side of the HMD 1 correspond to the upper side, the lower side, the right side, the left side, the front side, and the rear side, respectively, for the user wearing the wearing tool 8. To do.

<Installation tool 8, connection tool 9>
The mounting tool 8 is made of a flexible material such as resin or metal (for example, stainless steel). The mounting tool 8 includes a first portion 8A and second portions 8B and 8C. The first portion 8A and the second portions 8B and 8C are each a curved elongated plate-like member. The first portion 8A extends in the left-right direction and is curved in a convex shape on the front side. The second portion 8B extends from an end portion on one side (for example, the left side) of the first portion 8A. The second portion 8C extends from the end portion on the other side (for example, the right side) of the first portion 8A. The second portions 8B and 8C each extend in a direction in which end portions on the opposite side (for example, rear side) to the side connected to the first portion 8A approach each other. The wearing tool 8 is worn on the user's head with the first part 8A, the second part 8B, and 8C in contact with the frontal, right and left heads of the user, respectively. Is done. In this state, the first portion 8A extends in the left-right direction along the forehead of the user.

  The connection tool 9 is rod-shaped. The connection tool 9 is made of resin or metal. One end side (for example, the upper side) of the connection tool 9 is connected to the first portion 8A of the mounting tool 8. The connection tool 9 and the mounting tool 8 are connected by a ball joint. A display device 11 to be described later is connected to the other end side (for example, the lower side) of the connection tool 9. The connection tool 9 and the display device 11 are connected by a ball joint. The connection tool 9 holds the display device 11 at a position separated from the mounting tool 8. The connection tool 9 can move the display device 11 within a predetermined movable range by ball joints at both ends.

  The HMD 1 uses the half mirror 56 of the display device 11 when the mounting tool 8 is worn on the user's head in the state of FIG. 1 in which the display device 11 is disposed below the mounting tool 8. Can be placed in front of the left eye of the person. In this case, the connection tool 9 extends from the connection part with the mounting tool 8 toward the front obliquely lower side.

<Display device 11>
As shown in FIGS. 1 and 2, the display device 11 includes a box-shaped housing 12 that is long in the left-right direction. The left end of the housing 12 is open. The holder 5 is held in the opening portion of the housing 12. The holder 5 fixes the half mirror 56 to the housing 12. The front side of the half mirror 56 is not covered by the housing 12. An operation member 3 is provided on the front side surface of the housing 12. As shown in FIG. 3, the housing 12 accommodates the adjustment mechanism 4, the lens unit 6, and the image unit 7. The left side of the lens unit 6 is not covered by the housing 12. A communication line 28 (see FIG. 2) is connected to the rear side of the right end portion of the housing 12. The HMD 1 is connected to an external device (not shown) via the communication line 28. The external device supplies image data and power to the HMD 1.

  As shown in FIG. 3, the housing 12 is formed by combining a front housing 13 and a rear housing 14. The holder 5, the lens unit 6, and the image unit 7 are arranged in order from the left side to the right side. The adjustment mechanism 4 is disposed on the front side of the lens unit 6. A groove portion 242 recessed toward the rear is provided at a position including the center in the vertical direction on the front surface of the rear housing 14. The groove 242 extends in a straight line in the left-right direction.

  The image unit 7 generates and emits image light of an image corresponding to image data received from an external device via the communication line 28 (see FIG. 2). The image unit 7 includes a first holding member 71, a liquid crystal unit 72, and a second holding member 73. The first holding member 71 includes a cylindrical member 71A and side plate members 71B, 71C, 71D. The cylindrical member 71A is a substantially cylindrical member extending in the left-right direction. Each optical axis of a plurality of lenses 63 to be described later is disposed on an axis extending in the left-right direction at the center of the cylindrical member 71A. The side plate members 71B, 71C, 71D are flat plate-like members extending from the right end portion of the cylindrical member 71A to the right side. Each of the plane surfaces of the side plate members 71B and 71C faces the front-rear direction. Each of the flat surfaces of the side plate member 71D faces the up-down direction. The lower end of the side plate member 71B is connected to the front end of the side plate member 71D, and the lower end of the side plate member 71C is connected to the rear end of the side plate member 71D. The side plate member 71 </ b> C is held by the rear housing 14. As a result, the position of the image unit 7 with respect to the housing 12 is fixed.

  The liquid crystal unit 72 includes a light source 72A, a light guide member 72B, and a liquid crystal display element 72C. The liquid crystal unit 72 is disposed in a portion of the first holding member 71 surrounded by the side plate members 71B, 71C, 71D. The liquid crystal display element 72C has a rectangular shape. The display method of the liquid crystal display element 72C is a reflection type. A display surface 721 (see FIG. 7 and the like) of the liquid crystal display element 72C corresponds to the left side surface of the liquid crystal display element 72C. The light guide member 72B is fixed to the liquid crystal display element 72C in a state where the display surface 721 of the liquid crystal display element 72C is sealed (for example, in close contact) with a sealing member. The light guide member 72B can efficiently reflect the light incident from above to the right, and can efficiently transmit the light incident from the right to the left. The light guide member 72B is, for example, a polarization beam splitter that transmits only one of two types of polarization components orthogonal to each other and reflects the other. The most downstream surface of the light path of the image light in the light guide member 72B, that is, the surface opposite to the liquid crystal display element 72C side of the light guide member 72B (hereinafter referred to as “outer surface 722”, see FIG. 7). It inclines with respect to the plane orthogonal to the optical path. The light source 72A is connected to the upper surface of the light guide member 72B. In the liquid crystal unit 72, the light emitted from the light source 72A passes through a diffusion plate (not shown) and is dispersed into uniform light in the plane. Furthermore, the light that has passed through the diffusion plate is linearly deflected by passing through a deflection plate (not shown). The light that has passed through the polarizing plate is reflected by the light guide member 72B toward the liquid crystal display element 72C and enters the liquid crystal display element 72C. The incident light is reflected on the display surface 721 of the liquid crystal display element 72C. The reflected light corresponds to the image light of the image displayed on the display surface 721 of the liquid crystal display element 72C. Note that the direction of polarization of the image light is rotated with reflection on the display surface 721. The image light emitted from the liquid crystal display element 72C enters the light guide member 72B and exits from the outer surface 722 side.

  The second holding member 73 has a holding portion 73A and a control board 73B. The holding portion 73A is disposed on the right side of the liquid crystal display element 72C. The control board 73B is disposed on the right side of the holding portion 73A. The control board 73B is connected to the liquid crystal display element 72C via a flexible printed board (not shown). The communication line 28 (see FIG. 2) is connected to the control board 73B. The control board 73 </ b> B receives the image data transmitted from the external device via the communication line 28. The control board 73B displays an image corresponding to the image data on the display surface 721 by outputting a control signal to the liquid crystal display element 72C via the flexible printed board.

  The lens unit 6 is arranged downstream of the optical path of the image light with respect to the image unit 7. The image light is emitted from the outer surface 722 of the light guide member 72B. The lens unit 6 guides the image light emitted from the image unit 7 to the half mirror 56. The lens unit 6 includes a holding member 61, a cylindrical member 62, and a plurality of lenses 63. The holding member 61 is a substantially cylindrical member extending in the left-right direction. A plurality of lenses 63 are fixed inside the holding member 61. Each optical axis of the plurality of lenses 63 is disposed on an axis extending in the left-right direction at the center of the holding member 61. The direction in which the optical axis of each of the plurality of lenses 63 extends coincides with the longitudinal direction of the housing 12. The holding member 61 has a front side surface 61A. The front side surface 61A is provided with a convex portion 64 that protrudes forward. The convex part 64 fits in the cam groove 42 (see FIG. 4) of the engaging part 4B of the adjusting mechanism 4 described later. On the rear side surface of the holding member 61, a convex portion (not shown) that protrudes rearward is provided. This convex part fits into the groove part 242 of the fourth housing 24. The lens unit 6 is held by the rear housing 14 so as to be movable in the left-right direction.

  The cylindrical member 62 is a substantially cylindrical member that extends in the left-right direction. The cylindrical member 62 is provided on the right side of the holding member 61. Each optical axis of the plurality of lenses 63 is arranged on an axis extending in the left-right direction at the center of the cylindrical member 62. The sectional shape of the outer wall surface of the cylindrical member 62 and the sectional shape of the inner wall surface of the cylindrical member 71A of the cylindrical member 71A of the image unit 7 are substantially equal. At least a part of the right side of the cylindrical member 62 fits inside at least a part of the left side of the cylindrical member 71A. The cylindrical member 62 and the cylindrical member 71A overlap in the left-right direction. The image light generated by the image unit 7 enters the lens unit 6 from the cylindrical member 62 side and exits from the holding member 61 side. The image light that passes through the lens unit 6 is collected by a plurality of lenses 63.

  The operation member 3 is a frustoconical member. The central axis of the operation member 3 extends in the front-rear direction. The operation member 3 is rotatable about the central axis. On the rear end surface of the operation member 3, a fitting groove (not shown) into which a protruding portion 4A (described later) of the adjusting mechanism 4 is fitted is provided.

  The adjustment mechanism 4 has a protruding portion 4A and an engaging portion 4B. The engaging portion 4B is a circular plate member. Hereinafter, the center of the engaging portion 4B is referred to as “center X”. The protruding portion 4A protrudes forward from the vicinity of the center X of the engaging portion 4B. The protruding portion 4 </ b> A enters the hole 21 </ b> D on the front side surface of the front housing 13 from the rear side and protrudes to the front side from the front side surface of the front housing 13. The protruding portion 4A is fitted in the fitting groove on the rear end surface of the operation member 3. As a result, the operation member 3 and the adjustment mechanism 4 are held by the front housing 13. The adjustment mechanism 4 can rotate integrally with the operation member 3 around an axis extending in the front-rear direction through the center X of the engagement portion 4B. As shown in FIG. 4, a cam groove 42 is provided on the rear surface of the engaging portion 4B. The cam groove 42 is formed when a part of the rear side surface of the engaging portion 4B is recessed forward. The cam groove 42 extends spirally around the center X of the engaging portion 4B. The cam groove 42 is separated from the center X as it turns clockwise as viewed from the rear side. The cam groove 42 has a first end 42A and a second end 42B. The first end 42A is an end portion in the clockwise direction of the cam groove 42, and the second end 42B is an end portion in the counterclockwise direction. The convex portion 64 of the lens unit 6 is fitted into the cam groove 42 from the rear in a state where the operation member 3 and the adjustment mechanism 4 are held by the front housing 13.

  As shown in FIG. 3, the half mirror 56 is disposed downstream of the optical path of the image light with respect to the lens unit 6, that is, on the side opposite to the image unit 7 side with respect to the lens unit 6. The half mirror 56 is held by the holder 5. The position of the half mirror 56 with respect to the housing 12 is fixed by the holder 5. One surface 56B of both surfaces of the half mirror 56 faces right diagonally backward, and the other surface 56C faces diagonally left forward. The half mirror 56 can reflect a part (for example, 50%) of the light incident from the surface 56B side and transmit a part of the light (for example, 50%) incident from the surface 56C side. For this reason, the half mirror 56 can reflect a part of the image light emitted from the lens unit 6 in a direction (rear direction) intersecting with the extending direction of each optical axis of the plurality of lenses 63. The user's eyes can visually recognize the virtual image based on the image light reflected by the half mirror 56. Further, the half mirror 56 can transmit a part of the external light incident from the front side to the rear side.

  In the present invention, instead of the half mirror 56 described above, a reflective member capable of a general mirror that does not transmit background light may be used. Further, instead of the half mirror 56, an optical path deflecting member such as a prism or a diffraction grating may be used.

  The movement of the lens unit 6 when the user rotates the operation member 3 to adjust the focus will be described with reference to FIGS. When the adjusting mechanism 4 rotates according to the rotation of the operation member 3, the convex portion 64 (see FIG. 3) moves along the cam groove 42 (see FIG. 4) of the engaging portion 4B. For this reason, the lens unit 6 moves in the left-right direction in accordance with the rotation of the adjustment mechanism 4. As shown in FIG. 5, when the operation member 3 is rotated clockwise when viewed from the front side, the adjustment mechanism 4 is also rotated clockwise when viewed from the front side according to the rotation of the operation member 3 (arrow 43 in FIG. 4). ). When the cam groove 42 rotates clockwise from the state in which the convex portion 64 is in contact with the second end 42B (see FIG. 4), a force is applied to the right side of the convex portion 64 to move the convex portion 64 to the right side. Let As the convex part 64 moves, the lens unit 6 moves to the right side. When the convex portion 64 contacts the first end 42A (see FIG. 4) of the cam groove 42, the clockwise rotation of the operating member 3 is restricted. At this time, the liquid crystal display element 72C (see FIG. 3) of the image unit 7 and the plurality of lenses 63 (see FIG. 3) of the lens unit 6 are closest to each other. Hereinafter, the state of the display device 11 when the lens unit 6 and the image unit 7 are closest to each other is referred to as a “first state”.

  As shown in FIG. 6, when the operation member 3 is rotated counterclockwise when viewed from the front side, the adjusting mechanism 4 is also rotated counterclockwise when viewed from the front side according to the rotation of the operation member 3 (see FIG. 4). Rotate in the direction of arrow 44). When the cam groove 42 rotates counterclockwise from the state in which the convex portion 64 is in contact with the first end 42A (see FIG. 4), a force is applied to the left side of the convex portion 64, and the convex portion 64 is moved to the left side. Move. As the convex portion 64 moves, the lens unit 6 moves to the left side. When the convex portion 64 contacts the second end 42B of the cam groove 42, the counterclockwise rotation of the operation member 3 is restricted. At this time, the liquid crystal display element 72C of the image unit 7 and the plurality of lenses 63 of the lens unit 6 are most separated. Hereinafter, the state of the display device 11 when the lens unit 6 and the image unit 7 are farthest from each other is referred to as a “second state”.

  When the lens unit 6 moves in the left-right direction, the spread angle of the image light that becomes a virtual image visually recognized by the user is changed by the plurality of lenses 63. Therefore, the user can adjust the focus by rotating the operation member 3.

<Arrangement of Exit Pupil 21, Lens Unit 6, and Image Unit 7>
The arrangement of the exit pupil 21, the lens unit 6, and the image unit 7 will be described. In FIG. 7, the exit pupil 21, the plurality of lenses 63, the light source 72A, the light guide member 72B, and the liquid crystal display element 72C are schematically shown. The half mirror 56 is omitted. Further, in FIG. 7, a sealing member for sealing the display surface 721 of the liquid crystal display element 72C in the light guide member 72B is omitted. Each optical axis of the plurality of lenses 63 is denoted as “optical axis 20”. The principal point of the plurality of lenses 63 is denoted as “principal point 20B”. The focal length of the plurality of lenses 63 is expressed as “f” [mm]. The intersection of the outer surface 722 of the light guide member 72B and the optical axis 20 is referred to as a “first point 20C”. The intersection of the display surface 721 of the liquid crystal display element 72C and the optical axis 20 is denoted as “second point 20D”. The distance between the main point 20B and the first point 20C is expressed as “a (s)” [mm]. The distance between the main point 20B and the second point 20D is expressed as “a (i)” [mm]. The distance between the first point 20C and the second point 20D is expressed as “d” [mm]. d corresponds to the distance in the direction along the optical axis 20 between the outer surface 722 of the light guide member 72B and the display surface 721 of the liquid crystal display element 72C. d is the same value as a value “a (i) −a (s)” [mm] obtained by subtracting a (s) from a (i).

  As described above, the light source 72A is provided with a diffusion plate and a polarizing plate (not shown). Therefore, the light emitted from the light source 72A is linearly polarized. The polarized light is reflected by the light guide member 72B and is incident on the liquid crystal display element 72C. The incident light is reflected on the display surface 721 of the liquid crystal display element 72C. The reflected light corresponds to the image light of the image displayed on the display surface 721 of the liquid crystal display element 72C. As the image light emitted from the liquid crystal display element 72C is reflected on the display surface 721, the direction of polarization of the image light is rotated. Therefore, the image light passes through the outer surface 722 of the light guide member 72 </ b> B and is incident on the plurality of lenses 63. The image light is refracted and emitted from the plurality of lenses 63. The image light emitted from the plurality of lenses 63 is reflected by the half mirror 56 (see FIG. 3 and the like) and enters the user's eyes. Hereinafter, a plane orthogonal to the optical axis 20 and in contact with the most downstream portion of the optical path among the plurality of lenses 63 is referred to as a “third surface 631”. The intersection of the third surface 631 and the optical axis 20 is denoted as “third point 20A”. The distance between the third point 20A and the exit pupil 21 is expressed as “E” [mm]. E corresponds to the so-called eye relief length.

  When the operation member 3 (see FIG. 3) is operated, the plurality of lenses 63 move along the optical axis 20 in accordance with the rotation of the adjustment mechanism 4 (see FIG. 3). In the first state in which the lens unit 6 and the image unit 7 are closest (see FIG. 5), the distance a (i) between the principal point 20B of the plurality of lenses 63 and the second point 20D of the liquid crystal display element 72C. Is the shortest. In the second state (see FIG. 6) in which the lens unit 6 and the image unit 7 are most separated, a (i) is the longest. When the positions of the plurality of lenses 63 in the direction along the optical axis 20 are adjusted so that the image light is focused on the user's eyes, the image light is focused on the retina by the crystalline lens.

  The user recognizes the virtual image of the image displayed on the liquid crystal display element 72C in response to the image light entering the retina. In FIG. 7, the virtual image recognized by the user based on the image displayed on the liquid crystal display element 72 </ b> C is referred to as “image virtual image 77 </ b> C”. The image virtual image 77C is disposed on the side opposite to the plurality of lenses 63 with respect to the display surface 721 of the liquid crystal display element 72C. The intersection of the virtual line extending along the optical axis 20 and the image virtual image 77C is denoted as “intersection 20F”. The distance between the main point 20B and the intersection point 20F is expressed as “b (i)” [mm]. In this case, b (i) is larger than the distance a (i) (see FIG. 7) between the main point 20B and the second point 20D.

  Further, although the user does not directly recognize the light guide member 72B itself, for example, when foreign matter such as dust adheres to the outer surface 722 of the light guide member 72B, the user can recognize a virtual image of the foreign matter. There is sex. In FIG. 7, the virtual image of the foreign material recognized by the user based on the foreign material attached to the light guide member 72B is referred to as a “foreign material virtual image 77B”. The foreign object virtual image 77B is disposed on the side opposite to the plurality of lenses 63 with respect to the outer surface 722 of the light guide member 72B and on the plurality of lenses 63 side than the image virtual image 77C. The intersection of the virtual line extending along the optical axis 20 and the foreign object virtual image 77B is denoted as “intersection 20E”. The distance between the principal point 20B and the intersection point 20E is expressed as “b (s)” [mm]. In this case, b (s) is larger than a (s) (see FIG. 7) and smaller than b (i).

  The case where the adjustment mechanism 4 rotates in response to the operation member 3 (see FIG. 3) being operated and the plurality of lenses 63 are moved in the direction along the optical axis 20 will be exemplified. In this case, the intersection of the principal point 20B of the plurality of lenses 63 and the virtual image 77C according to a change in the distance a (i) between the principal point 20B of the plurality of lenses 63 and the second point 20D of the liquid crystal display element 72C. The distance b (i) between 20F also changes. In the first state (see FIG. 5) in which the lens unit 6 and the image unit 7 are closest, a (i) and b (i) are the smallest. In the second state (see FIG. 6) in which the lens unit 6 and the image unit 7 are most separated from each other, a (i) and b (i) are the largest.

  Hereinafter, the position of the image virtual image 77C when b (i) is the smallest is referred to as a “first position”. The position of the image virtual image 77C when b (i) is the largest is referred to as a “second position”. Note that both the first position and the second position are arranged on the opposite side of the plurality of lenses 63 with respect to the display surface 721 of the liquid crystal display element 72C. Further, the image virtual image 77C is arranged at any position between the first position and the second position (hereinafter referred to as “specific position”) in response to the operation of the operation member 3. b (i) corresponds to the distance between the intersection 20F of the image virtual image 77C arranged at the specific position and the principal points 20B of the plurality of lenses 63.

  Note that the foreign object virtual image 77B moves within the range between the outer surface 722 of the light guide member 72B and the virtual image 77C in response to the virtual image 77C moving between the first position and the second position. Further, the distance b (s) between the principal point 20B of the plurality of lenses 63 and the intersection 20E of the foreign object virtual image 77B is also the distance b (b) between the principal point 20B of the plurality of lenses 63 and the intersection 20F of the image virtual image 77C. i) changes in response to changes. In a state where the distance b (i) between the principal point 20B of the plurality of lenses 63 and the intersection 20F of the image virtual image 77C is the smallest, that is, the image virtual image 77C is disposed at the first position, b (s) is The smallest. However, b (s) in this case is larger than the distance a (s) between the principal point 20B of the plurality of lenses 63 and the first point 20C of the light guide member 72B (see FIG. 7). On the other hand, b (s) becomes the largest in the state where b (i) is the largest, that is, in the state where the image virtual image 77C is arranged at the second position. However, b (s) in this case is smaller than the distance b (i) between the principal point 20B and the intersection 20F of the image virtual image 77C.

In the above, the distance a (i) between the principal point 20B of the plurality of lenses 63 and the second point 20D of the liquid crystal display element 72C, and the intersection 20F of the principal point 20B of the plurality of lenses 63 and the image virtual image 77C. The distance b (i) between them and the composite focal point f of the plurality of lenses 63 have the relationship of the following equation (1).
1 / f = 1 / a (i)-1 / b (i) (1)
In the above, the distance a (s) between the principal point 20B of the plurality of lenses 63 and the first point 20C of the light guide member 72B, and the intersection 20E of the principal point 20B of the plurality of lenses 63 and the foreign object virtual image 77B. And the synthetic focus f of the plurality of lenses 63 have the relationship of the following formula (2).
1 / f = 1 / a (s)-1 / b (s) (2)
In the relationship of the above formulas (1) and (2), both b (i) and b (s) are positive values. Further, a (s) can be expressed as the following equation (3) using the distance d between the first point 20C of the light guide member 72B and the second point 20D of the liquid crystal display element 72C. it can.
a (s) = a (i)-d (3)

In the above, when the foreign object virtual image 77B is visually recognized by the user, the image quality when the image virtual image 77C is visually recognized by the user is deteriorated. For this reason, it is desirable that the foreign object virtual image 77B is always arranged at a focus position that is difficult for the user to visually recognize. Here, it is said that the average near point distance of the eyes of people in their 20s is about 100 mm from the pupil. That is, it is difficult for a person in his twenties to focus his eyes on an object that is present at a position closer than about 100 mm from the pupil, that is, a foreign object virtual image 77B that is present at a position closer than 100 mm. That is,
b (s) <100 [mm] (4)
The following relational expression is obtained.

The relationship between f, b (i), and d that satisfies Expression (4) is derived as follows based on Expressions (1), (2), and (3). By transforming equation (1), the following equation (5) is derived. Further, the following equation (6) is derived by modifying the equations (2) and (3).
a (i) = (f * b (i)) / (b (i) + f) (5)
b (s) = f * (a (i)-d) / (f-(a (i)-d)) (6)
By further modifying the equation (5), the following equation (7) is derived.
a (i)-d = (b (i) * (f-d)-d * f) / (b (i) + f) (7)

Substituting equation (7) into equation (6) yields the following equation (8):
b (s) = (f * (b (i) * f-b (i) * d-d * f)) / (f ² + b (i) * d + d * f) (8)
In Expression (8), since it is sufficient to satisfy the relationship of Expression (4), the following Expression (9) is derived as the relationship of f, b (i), and d.
(f * (b (i) * f-b (i) * d-d * f)) / (f ² + b (i) * d + d * f) <100 [mm] (9)
(However, b (i)> 0, f> 0, d> 0)

  That is, when f, b (i), and d are set so as to satisfy the relationship of Expression (9), the distance b (s) between the principal point 20B of the plurality of lenses 63 and the intersection 20E of the foreign object virtual image 77B. Is smaller than 100 mm. In this case, since it becomes difficult for the user to focus on the foreign object virtual image 77B attached to the intersection 20E of the light guide member 72B, it is difficult to visually recognize the foreign object virtual image 77B. For this reason, even when a foreign object adheres to the outer surface 722 of the light guide member 72B, the image quality of the image virtual image 77C visually recognized by the user is maintained.

  Note that the state of the display device 11 changes between the first state and the second state in accordance with the operation of the operation member 3 (see FIG. 3). In the second state (see FIG. 6) in which the plurality of lenses 63 and the liquid crystal display element 72C are farthest from each other (see FIG. 6), the image virtual image 77C is disposed at the second position. The distance b (i) between is the largest. In this state, the distance b (s) between the principal point 20B of the plurality of lenses 63 and the intersection 20E of the foreign object virtual image 77B is also the largest. For this reason, if b (i) when the image virtual image 77C is arranged at the second position is applied to the left side of the equation (9), if the relationship of the equation (9) is satisfied, the image virtual image 77C Even if the position changes between the first position and the second position, b (s) is always less than 100 mm. For this reason, even when the plurality of lenses 63 move according to the operation of the operation member 3, the user is difficult to always visually recognize the foreign object virtual image 77B attached to the intersection 20E of the light guide member 72B.

  In the above description, the virtual image position generated by the plurality of lenses 63 has been discussed. However, actually, the image light emitted from the plurality of lenses 63 is incident on the user's eyes via the half mirror 56. For this reason, the position of the exit pupil is separated downstream of the optical path with respect to the principal point 20B of the plurality of lenses 63. Therefore, an equation considering the distance E corresponding to the eye relief length is examined.

  In FIG. 8, the intersection of the half mirror 56 and the optical axis 20 is denoted as “fourth point 21 </ b> A”. The distance between the third point 20A, which is the intersection of the third surface 631 that is closest to the downstream of the optical path among the plurality of lenses 63, and the optical axis 20, and the fourth point 21A is referred to as a “first distance”. Indicated as “e1” [mm]. A point of the housing 12 that protrudes most in the traveling direction of the image light reflected by the half mirror 56 (hereinafter referred to as “specific direction”) is referred to as a “fifth point 12A”. In FIG. 8, the backward direction corresponds to the specific direction. The most protruding point in the rear direction in the housing 12 corresponds to the fifth point 12A. A distance in a specific direction between the fourth point 21A and the fifth point 12A is referred to as a “second distance” and expressed as “e2” [mm]. In this case, the distance E between the third point 20A and the exit pupil 21 is larger than “e1 + e2” by the distance e3. Note that the user's pupil may be placed at the position of the exit pupil 21 in FIG. 8 in a state where the HMD 1 is worn by the user. The reason is that vignetting can be avoided by making the pupil coincide with the position of the exit pupil 21.

As described above, when an actual use environment in which the plurality of lenses 63 are separated from the user's pupil is considered, the foreign object virtual image 77B attached to the intersection 20E of the light guide member 72B is difficult to be visually recognized by the user. In order to achieve this, it is necessary to satisfy the relationship of the following equation (10) obtained by modifying equation (4).
(b (s) + E) <100 [mm] (E> 0) (10)
In b (s) expressed by equation (8), the relationship of equation (10) only needs to be satisfied, and therefore the following equation (11) is derived as the relationship of f, b (i), and d. The
(f * (b (i) * f-b (i) * d-d * f)) / (f ² + b (i) * d + d * f) + E <100 [mm] (11)
If the eye relief length (distance E) is sufficiently shorter than b (s), E on the left side of the equation (11) can be ignored. In this case, equation (11) matches equation (9).

  That is, when f, b (i), and d are set so as to satisfy the relationship of Expression (11), the user is located at a position E separated from the third point 20A of the plurality of lenses 63 corresponding to the eye relief length. B (s) is smaller than 100 mm even when the pupils are arranged. In this case, since it becomes difficult for the user to focus on the foreign object virtual image 77B attached to the intersection 20E of the light guide member 72B, it is difficult to visually recognize the foreign object virtual image 77B. For this reason, in the actual use environment of HMD1, even when a foreign object adheres to the outer surface 722 of the light guide member 72B, the image quality of the image virtual image 77C visually recognized by the user is maintained.

  FIG. 9 shows a state where the half mirror 56 of the display device 11 is arranged at a position separated from the left eye of the user. This state corresponds to a state where the user lifts the display device 11 in the state of FIG. 1 upward. The connection tool 9 extends rearward and obliquely upward from a connection portion with the mounting tool 8. The position of the display device 11 in FIG. 9 corresponds to a position farthest from the mounting tool 8 in the movable range. In FIG. 9, the length of the shortest line segment connecting the mounting tool 8 and the display device 11 is expressed as “L2” [mm]. In FIG. 1, the length of the shortest line segment among the line segments connecting the wearing tool 8 and the display device 11 is expressed as “L1” [mm]. In this case, L2 is larger than L1. Further, the value of E corresponding to the eye relief length of the display device 11 is smaller than L2.

<Simulation results>
In the graph of FIG. 10, the relationship between f and b (s) satisfying the relationship of Expression (8) is shown for each of two values of b (i) (10000 mm, 300 mm). f is the focal length of the plurality of lenses 63. b (s) is the distance between the principal point 20B of the plurality of lenses 63 and the intersection 20E of the foreign object virtual image 77B. b (i) is the distance between the principal point 20B of the plurality of lenses 63 and the intersection 20F of the image virtual image 77C. The distance d between the liquid crystal display element 72C and the second point 20D is 5.5 mm. In FIG. 10, the range of the value of f for satisfying the condition “b (s) <100 (mm)” of Expression (4) is about 26.5 mm or less when b (i) is 10,000 mm, and b ( When i) is 300 mm, it is about 35 mm or less. From this result, when f is at least about 26 mm or less, b (s) is always 100 mm or less regardless of the value of b (i).

  In the grab of FIG. 11, the relationship between d and b (s) satisfying the relationship of Expression (8) is two b (i) values (10000 mm, 300 mm) and two f values (25 mm, 20 mm). ) Is shown every time. d is a distance between the first point 20C of the light guide member 72B and the second point 20D of the liquid crystal display element 72C. In FIG. 11, the range of the value of d for satisfying the condition “b (s) <100 (mm)” of Expression (4) is about 5. When f is 25 mm and b (i) is 10,000 mm. 0 mm or more, and about 3.0 mm or more when b (i) is 300 mm. When f is 20 mm, the range of d is about 3.3 mm or more when b (i) is 10,000 mm, and about 2.0 mm or more when b (i) is 300 mm. From this result, by setting d to at least about 5 mm or more, regardless of the value of b (i), b (s) is always 100 mm or less regardless of whether f is 20 mm or 25 mm.

  In the grab of FIG. 12, when the value of f is 21.5 mm, the relationship between d and b (s) satisfying the relationship of Expression (8) is two values of b (i) (600 mm, 300 m). Is shown in FIG. 12 corresponds to a graph in which the larger of the two b (i) values in the graph of FIG. 11 is changed from 10000 mm to 600 mm and the value of f is 21.5 mm. In FIG. 12, the range of the value of d for satisfying the condition “b (s) <100 (mm)” of Expression (4) is about 3.0 mm or more when b (i) is 600 mm, and b ( When i) is 300 mm, it is about 2.3 mm or more. From this result, when f is at least about 21.5 mm and d is about 3.0 mm or more, when b (i) is in the range of about 300 mm to about 600 mm, b (s) is It is always 100 mm or less.

  In the graph of FIG. 13, the relationship between f and (b (s) + E) satisfying the relationship of Expression (10) is shown for each of a plurality of b (i) (= 10000 mm, 300 mm). In FIG. 13, 35 mm is added as E to b (s) in the grab of FIG. As in FIG. 10, the distance d is set to 5.5 mm. In FIG. 13, the range of the value of f for satisfying the condition “(b (s) + E) <100 (mm)” of the expression (10) is about 22 mm or less when b (i) is 10,000 mm, and b When (i) is 300 mm, it is about 26.5 mm or less. From this result, when the eye relief length is set to 35 mm, by setting f to at least about 21 mm or less, b (s) is always 100 mm or less regardless of the value of b (i).

<Main functions and effects of this embodiment>
As described above, in the display device 11 of the HMD 1, when f, b (i), and d satisfy the relationship of Expression (9), the distance between the principal point 20B of the plurality of lenses 63 and the intersection 20E of the foreign object virtual image 77B. The distance b (s) is shorter than 100 mm. In this case, it becomes difficult for the user to always visually recognize the foreign substance virtual image 77B of the foreign substance attached to the light guide member 72B. Therefore, the display device 11 can suppress the image quality of the image virtual image 77C visually recognized by the user from being deteriorated due to the presence of the foreign matter attached to the light guide member 72B.

  The display device 11 has an adjustment mechanism 4. When the adjustment mechanism 4 moves the lens unit 6 along the optical path, the positions of the image virtual image 77C and the foreign object virtual image 77B move. For this reason, depending on the position of the foreign object virtual image 77B after movement, the eye may be focused on the foreign object virtual image 77B at any position, and the user may be able to visually recognize the foreign object virtual image 77B. On the other hand, in the display device 11, if the relationship of the expression (9) is satisfied with respect to b (s) when the image virtual image 77C is located at a specific position between the first position and the second position, the image is displayed. When the virtual image 77C is located between the specific position and the first position, b (s) is shorter than 100 mm. Accordingly, the display device 11 allows the moving range of the image virtual image 77C, which enables the adjustment mechanism 4 to adjust the focus of the image virtual image 77C, and suppresses the deterioration of the image quality due to the foreign matter attached to the light guide member 72B, from the specific position and the first position. Can be secured between the position.

  In the display device 11, by setting d to at least about 5 mm or more, b (s) is always 100 mm or less regardless of the value of b (i) regardless of whether f is 20 mm or 25 mm (see FIG. 11). When d is smaller than 5 mm, the range of values of f that can be adopted by the plurality of lenses 63 is narrowed. That is, when the user focuses on the image virtual image 77C, the range of the value of f that may be focused on the foreign object virtual image 77B and visually recognize the virtual image becomes undesirably large. On the other hand, when d is at least about 5 mm or more, the range of the value of f that can be adopted by the plurality of lenses 63 can be expanded while maintaining the state in which the foreign object virtual image 77B is difficult for the user to visually recognize. For this reason, the range of f in which a virtual image is visually recognized by the user can be narrowed by focusing on the foreign object virtual image 77B. Accordingly, the foreign object virtual image 77B can be more appropriately suppressed from being visually recognized by the user.

  In the display device 11, when f is at least about 21.5 mm and d is 3.0 mm or more, b (s) is 100 mm or less when d is in the range of at least about 300 mm to about 600 mm. (See FIG. 12). For example, assuming a typical size of the liquid crystal display element 72C (for example, 0.5 to 0.7 inches diagonally), in a portion where the distance between the light guide member 72B and the liquid crystal display element 72C is short, d is At least about 3 mm or more is desirable. In order to obtain a relatively large angle of view (for example, 20 to 30 ° diagonally), f is preferably about 21.5 mm or less. On the other hand, by setting b (i) to 300 mm or more and 600 mm or less, the display device 11 deteriorates the image quality due to the presence of foreign matter attached to the light guide member 72B even when the above conditions d and f are satisfied. This can be suppressed.

  The display device 11 is fixed to the user's head via the wearing tool 8 and the connecting tool 9. The image light emitted from the plurality of lenses 63 enters the user's eyes via the half mirror 56. For this reason, the position of the user's pupil is separated downstream of the optical path with respect to the principal point 20 </ b> B of the plurality of lenses 63. On the other hand, in the display device 11, when f, b (i), d, and E corresponding to the eye relief length satisfy the relationship of Expression (11), the principal point 20B of the plurality of lenses 63 and the foreign object virtual image 77B. It was found that the distance b (s) between the intersection 20E and the intersection 20E was shorter than 100 mm. Accordingly, when the condition of the expression (11) is satisfied, the display device 11 allows the user to visually recognize the foreign object virtual image 77B even when the display device 11 is attached to the user with a space from the user's eyes. This can be suppressed.

  The outer surface 722 of the light guide member 72B is inclined with respect to a plane orthogonal to the direction extending along the optical path. d corresponds to the distance between the first point 20C, which is the intersection of the outer surface 722 and the optical axis 20, and the second point 20D, which is the intersection of the display surface 721 of the liquid crystal display element 72C and the optical axis 20. For this reason, when f, b (i), and d satisfy the relationship of Expression (9), or when f, b (i), d, and E satisfy the relationship of (11), the display device 11 is liquid crystal. When a foreign object adheres to the outer surface 722 of the light guide member 72B corresponding to the center position of the display surface 721 of the display element 72C, it is possible to prevent the user from visually recognizing the foreign object virtual image 77B of the foreign object.

  The display device 11 includes a housing 12 that houses a light source 72 </ b> A, a light guide member 72 </ b> B, a liquid crystal display element 72 </ b> C, and a plurality of lenses 63. The housing 12 is long in the direction extending along the optical axis 20 of the plurality of lenses 63. Image light emitted from the plurality of lenses 63 is deflected by the half mirror 56 in a specific direction that intersects the longitudinal direction of the housing 12. E is longer by a third distance e3 than a value obtained by adding the first distance e1 and the second distance e2. In this case, the display device 11 can secure the third distance e3 between the display device 11 and the user while suppressing the user from visually recognizing the foreign object virtual image 77B. Therefore, the display device 11 can suppress the housing 12 from coming into contact with the user while being attached to the user.

  In the HMD 1, the length L 2 between the mounting tool 8 and the display device 11 in a state where the display device 11 is disposed at a position farthest from the mounting tool 8 in the movable range (see FIG. 9) is the length of the display device 11. It becomes larger than the value of E corresponding to the eye relief length. In this case, the HMD 1 can suppress the user from visually recognizing the foreign object virtual image 77 </ b> B even when the display device 11 is moved to any position within the movable range by the connector 9.

<Modification>
In addition, this invention is not limited to the said embodiment, A various change is possible. In the above, the adjusting mechanism 4 moves the display device 11 between the first position and the second position by changing the position of the lens unit 6 in the direction along the optical path. On the other hand, the adjustment mechanism 4 may move the state of the display device 11 between the first position and the second position by changing the position of the image unit 7 in the direction along the optical path. The adjusting mechanism 4 moves the lens unit 6 and the image unit 7 in the direction along the optical path, and changes the relative position of each to change the state of the display device 11 to the first position and the second position. You may move between. Further, the display device 11 may not include the adjusting mechanism 4 and the relative positional relationship between the lens unit 6 and the image unit 7 may be fixed.

  In the display device 11, b (i) corresponds to the distance between the main point 20 </ b> B and the intersection point 20 </ b> F when the image virtual image 77 </ b> C is disposed at a specific position between the first position and the second position. Further, in the display device 11, when b (s) when the image virtual image 77C is located at the specific position satisfies the relationship of Expression (9), the image virtual image 77C is located between the specific position and the first position. Further, the distance between the main point 20B and the intersection point 20E is shorter than 100 mm. On the other hand, b (i) may be defined as the distance between the main point 20B and the intersection 20F when the image virtual image 77C is arranged at the second position. Under such conditions, when b (s) satisfies the relationship of Expression (9), b (s) can be set to 100 mm or less in the entire range of movement of the virtual image 77C by the adjusting mechanism 4. Therefore, the display device 11 can suppress the image quality of the image virtual image 77C visually recognized by the user from being deteriorated by the foreign object virtual image 77B in the entire adjustment range of the position of the image virtual image 77C by the adjustment mechanism 4.

  In the above, it was found from the results of FIG. 11 that d is preferably at least about 5 mm or more. For this reason, in the display device 11, d is preferably at least about 5 mm or more, but d may be smaller than 5 mm. In the above, it was found from the results of FIG. 12 that b (i) is preferably at least in the range of about 300 mm to about 600 mm. For this reason, in the display device 11, b (i) is preferably at least in the range of about 300 mm to about 600 mm, but b (i) may be out of the range of about 300 mm to about 00 mm.

  In the above, d is defined based on the first point 20 </ b> C that is the intersection of the outer surface 722 and the optical axis 20. b (s) was defined with reference to the intersection 20E between the virtual line along the optical axis 20 and the foreign object virtual image 77B. On the other hand, d may be defined based on the point where the distance along the optical path between the outer surface 722 and the second point 20D of the liquid crystal display element 72C is the most separated. Further, b (s) may be defined based on the point in the foreign object virtual image 77B that is the farthest distance along the optical path between the image virtual image 77C and the intersection 20F. In this case, the display device 11 can suppress the user from visually recognizing the foreign object virtual image 77B of the foreign object regardless of the position of the external surface 722 of the light guide member 72B.

  In the above description, the light guide member 72B is fixed to the liquid crystal display element 72C in a state of being in close contact with the display surface 721 of the liquid crystal display element 72C. On the other hand, the light guide member 72B may be fixed at a position separated from the display surface 721. That is, a space may be provided between the light guide member 72B and the liquid crystal display element 72C. The outer surface 722 of the light guide member 72 </ b> B may be disposed along a plane orthogonal to the optical axis 20.

  The HMD 1 may be guided directly to the user's eyes without changing the traveling direction of the image light emitted from the image unit 7. That is, the image light may be emitted backward from the image unit 7 in a state where the HMD 1 is worn by the user (see FIG. 1). In this case, the optical axes of the plurality of lenses 63 of the lens unit 6 are directed in the front-rear direction. In this case, the HMD 1 may not include the half mirror 56. The display method of the HMD 1 is not limited to the above-described method of projecting an image on a part of the user's visual field, and may be a method of projecting an image on the entire user's visual field.

<Others>
The lens unit 6 is an example of the “eyepiece optical system” in the present invention. The adjustment mechanism 4 is an example of the “setting mechanism” in the present invention.

1: HMD
3: Operation member 4: Adjustment mechanism 6: Lens unit 7: Image unit 8: Mounting tool 9: Connection tool 11: Display device 12: Housing 12A: 5th point 20: Optical axis 20A: 3rd point 20B: Main point 20C: First point 20D: Second point 21: Exit pupil 21A: Fourth point 56: Half mirror 63: Lens 72: Liquid crystal unit 72A: Light source 72B: Light guide member 72C: Liquid crystal display element 77B: Foreign object virtual image 77C: Image Virtual image 721: Display surface 722: Light guide surface

Claims (7)

A light source;
A reflective liquid crystal display element capable of displaying an image;
A light guide member fixed to the liquid crystal display element and guiding light emitted from the light source to the liquid crystal display element;
An eyepiece optical system that is provided downstream of the light guide member and collects the image light in the optical path of the image light emitted from the liquid crystal display element based on the light guided by the light guide member;
A housing that houses the light source, the liquid crystal display element, the light guide member, and the eyepiece optical system, and that is long in a direction extending along the optical axis of the eyepiece optical system;
A deflecting member that is provided downstream of the eyepiece optical system in the optical path and deflects at least a part of the image light emitted from the eyepiece optical system in a specific direction intersecting a longitudinal direction of the housing; br />
The focal length of the eyepiece optical system is f [mm], the distance in the optical path between the principal point of the eyepiece optical system and the virtual image of the image is b [mm], and the liquid crystal display element and the light guide member When the distance in the optical path between and f is d [mm], f, b, and d are
(However, b> 0, f> 0, d> 0)
Meet the relationship,
When the distance from the most downstream surface in the optical path of the eyepiece optical system to the exit pupil is E [mm], the f, the b, the d, and the E are
(However, E> 0)
Satisfy the relationship
E is a third point where the third surface closest to the deflection member of the eyepiece optical system in the longitudinal direction of the housing intersects with the optical axis of the eyepiece optical system, and the deflection member and the eyepiece optical system. And a second distance in the specific direction between the fourth point and the fifth point that protrudes most in the specific direction in the housing. A display device characterized by being larger than the total distance . The position of the virtual image is a first position having the shortest distance in the optical path between the principal point of the eyepiece optical system and the virtual image, and the optical path between the principal point of the eyepiece optical system and the virtual image. A setting mechanism that can be set with the second position having the longest distance at
The b is a distance in the optical path between the principal point and the virtual image when the virtual image is located at a specific position between the first position and the second position. Item 4. The display device according to Item 1.   3. The display device according to claim 2, wherein b is a distance in the optical path between the principal point and the virtual image when the virtual image is located at the second position.   The display device according to claim 1, wherein the d is 5 mm or more.   The display device according to claim 1, wherein the b is 300 mm or more and 600 mm or less. The most downstream surface in the optical path of the light guide member is inclined with respect to the optical path,
The d is a first point where the most downstream surface of the light guide member intersects with the optical axis of the eyepiece optical system, and a display surface of the liquid crystal display element intersects with the optical axis of the eyepiece optical system. display device according to any one of claims 1 to 5, characterized in that the distance between the second point. The display device according to any one of claims 1 to 6 ,
A head-mounted display that is a member that attaches the display device to a mounting tool that is mounted on a user's head and includes a connection tool that can move the display device within a predetermined movable range. There,
The E is smaller than the distance between the mounting tool and the display device in a state where the display device is moved to a position farthest from the mounting tool within the movable range. .