JP2019179083A - Image display device - Google Patents

Abstract

To provide an image display device including a wide-angle compact optical system with which a difference in picture quality between left and right videos is small even when videos of different angles of view are displayed on left and right eyes.SOLUTION: The image display device comprises: two display elements each corresponding to the left and right eyes of an observer; and an eyepiece optical system for the left eye and an eyepiece optical system for the right eye for guiding the images of the display elements to each of the left and right eyes of the observer. The optical power on optical surface of the eyepiece optical system for the left eye for the left eye of the observer and the optical power on optical surface of the eyepiece optical system for the right eye for the right eye of the observer are the same, and the shape of optical surface of the eyepiece optical system for the left eye is bilaterally symmetrical to a vertical cross section including the visual axis of the left eye of the observer and the shape of optical surface of the eyepiece optical system for the right eye is bilaterally symmetrical to a vertical cross section including the visual axis of the right eye of the observer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image display device that displays an image on a display element via an optical system.

  Head mounted displays are being developed for the purpose of virtual reality (VR) or for enjoying large screen images alone.

  As an image display device used for a head-mounted display or the like, wide-angle image presentation is desired in order to perform natural observation and increase the sense of reality. Further, it is desirable that the head-mounted image display device is small.

  As a technology to achieve wide-angle image presentation, the same angle of view is applied to the left and right eyes by displaying images with different angles of view on the left and right eyes, and overlapping only a part of the angle of view with the left and right eyes. There has been proposed an image display device that enables observation of an image with a wider angle of view than when displaying the above video.

  Patent Documents 1 and 2 disclose examples of image display devices. In Patent Document 1, a technique for realizing a wide angle of view by displaying an image with different angles of view on the left and right eyes by arranging an optical system having an outer angle of view wider than the angle of view of the inner side in an inverted manner. Is disclosed. In Patent Document 2, the display centers of the left-eye and right-eye display elements are shifted leftward and rightward, respectively. A technique for realizing a wide angle of view by displaying images of different angles of view on the left and right eyes by shifting the images displayed on each display element leftward and rightward as viewed from the observer is disclosed. Yes.

JP 2012-242794 A JP-A-6-38246

  In general, the way in which aberrations occur in an optical system differs depending on the shape of the surface through which the light beam passes. Further, when the display of the image display device has a wide angle of view, the distance between human eyes is fixed, and the left and right optical systems may interfere inside. In the image display device described in Patent Document 1, since the left and right optical systems are reversed, when the left and right eyes observe an image with the same angle of view, the guided light beam passes through the surface of the optical system. The shape will be different on the left and right. For this reason, even when images with the same angle of view are observed on the left and right, the resolution and distortion are different on the left and right, resulting in an image that is difficult to fuse with both eyes. In the image display device described in Patent Document 2, only the display element is shifted so that the optical system is common to the left and right. However, the optical system is large because there is an optical system in a portion where no image is guided from the display element. It will become. In addition, the left and right optical systems interfere with each other on the inside, so that the angle of view cannot be increased.

  In view of the above problems, the present invention provides an image display apparatus having a small optical system with a wide angle of view and a small difference in image quality between the left and right images even when images of different angles of view are displayed on the left and right eyes. The purpose is to provide.

  Two display elements corresponding to the left and right eyes of the observer, an eyepiece optical system for the left eye and an eyepiece optical system for the right eye for guiding the images of the display elements to the left and right eyes of the observer, respectively And the optical power of the optical surface of the left eyepiece optical system for the left eye of the observer and the optical power of the eyepiece optical system for the right eye for the right eye of the observer The shape of the optical surface of the left eyepiece optical system is symmetric with respect to a vertical section including the visual axis of the left eye of the observer, and the right eyepiece optical system has the same optical shape. The shape of the surface is symmetric with respect to a vertical section including the visual axis of the right eye of the observer.

  According to the present invention, it is possible to provide an image display device having a small optical system with a wide angle of view and a small difference in image quality between left and right images even when images of different angles of view are displayed on the left and right eyes. it can.

1 is a top view of an image display device according to a first embodiment. The top view of the conventional image display apparatus. The top view of the conventional image display apparatus. The figure which shows how an image looks with both eyes. The top view of the other image display apparatus which concerns on 1st Embodiment. The top view of the image display apparatus which concerns on 2nd Embodiment. The side view of the image display apparatus which concerns on 2nd Embodiment. The top view of the other image display apparatus which concerns on 2nd Embodiment. Explanatory drawing of the reflective film of the reflective surface which concerns on 2nd Embodiment.

(First embodiment)
The configuration of the image display apparatus according to the first embodiment will be described with reference to the top view of the image display apparatus in FIG. In the figure, 101 is the right eye of the observer, 102 is the left eye of the observer, 103 is the eyepiece optical system for the right eye, 104 is the eyepiece optical system for the left eye, 105 is the display element for the right eye, and 106 is for the left eye. A display element 107 is a right eye visual axis, and 108 is a left eye visual axis. The right eye visual axis 107 and the left eye visual axis 108 are parallel.

  The right-eye eyepiece optical system 103 enlarges the right-eye display element 105 and leads it to the corresponding observer's right eye 101, and the left-eye eyepiece optical system 104 enlarges and handles the left-eye display element 106. To the left eye 102 of the observer. The center of the right-eye display element 105 is shifted to the right with respect to the vertical section including the right-eye viewing axis 107, and the display field angle of the right-eye eyepiece optical system 103 is 50 ° on the right side and 35 ° on the left side. . The center of the left-eye display element 106 is shifted to the left with respect to a vertical section including the left-eye visual axis 108, and the display field angle of the left-eye eyepiece optical system 104 is 35 ° on the right side and 50 ° on the left side. The angles of view displayed by the left and right eyepiece optical systems are different from each other. Therefore, when the observer observes with both eyes, the right side only observes from the right 50 ° to the right side 35 °, the right side 35 ° to the left side 35 ° observes with both eyes, and the left side 35 ° to the left side 50 °. Until then, observation is performed only with the left eye, and the entire horizontal angle of view is 100 °. In this way, images with different angles of view are displayed on the left and right eyes so that only a part of the angle of view overlaps with the left and right eyes. It is possible to observe an image with a wider angle of view than when displaying the video.

In the present embodiment, in the observation image of the right eye, the binocular region has an angle of view of 70 ° and the right eye region has an angle of view of 15 °, and the area of the observation image of the right eye region relative to the area of the observation image of the binocular region Is 35% according to the formula (1).
(Tan (50 °) -tan (35 °)) / (2 × tan (35 °)) = 0.35 Formula (1)
This ratio is desirably 45% or less. When the ratio is greater than 45%, the boundary between the binocular region and the monocular region comes near the center of the observation image, and thus the boundary is easily noticeable. In addition, since the ratio of the binocular region is small, the region that can be stereoscopically viewed is narrow, and natural stereoscopic observation is not possible. Further, this ratio is desirably 10% or more. When the ratio is smaller than 10%, the monocular region is narrowed and the effect of widening the angle of view is small. The same applies to the observation image of the left eye.

  The observer-side surfaces of the right-eye eyepiece optical system 103 and the left-eye eyepiece optical system 104 according to the present embodiment have a spherical shape with the same radius of curvature, and the right-eye eyepiece optical system 103 and the left-eye eyepiece optical system 104. The surface on the display element side has a spherical shape with the same radius of curvature. Therefore, all optical surfaces of the right-eye eyepiece optical system 103 have the same optical power as the optical surfaces of the left-eye eyepiece optical system 104 that are in the same positional relationship as the respective optical surfaces.

  Further, the optical axis of the right-eye eyepiece optical system 103 coincides with the right-eye visual axis 107, and the shapes of all the optical surfaces are expressed in a shape that is bilaterally symmetrical with respect to the vertical section including the right-eye visual axis 107. Has been. Similarly, the optical axis of the left-eye eyepiece optical system 104 also coincides with the left-eye visual axis 108, and the shapes of all optical surfaces are symmetrical with respect to the vertical section including the left-eye visual axis 108. It is expressed.

  Therefore, when the same angle of view is observed with the right eye 101 and the left eye 102, the shape of the surface of the optical system through which light rays with the angle of view pass is the same in the left and right eyepiece optical systems, and aberrations that occur in the eyepiece optical system The way out is the same on the left and right. Therefore, there is almost no difference between the right and left in the resolution and distortion, and the image is easily fused with both eyes.

  2, the right eyepiece optical system 109 and the left eyepiece optical system 110 are the same optical system, and the optical axis 111, the right eye visual axis 107, and the left eye of the right eyepiece optical system 109 are used. Consider a case where the optical axis 112 of the eyepiece optical system 110 for use and the left eye visual axis 108 do not coincide. At this time, when the same angle of view is observed with the right eye 101 and the left eye 102, the shape of the surface of the optical system through which light rays with the angle of view pass is different on the left and right. For example, the light beam having the left field angle guided to the right eye 101 passes through the vicinity of the left end of the right eyepiece optical system 109, but the light beam having the same field angle guided to the left eye 102 is left eyepiece eyepiece. It passes through a surface closer to the optical axis 112 than the vicinity of the left end of the optical system 110.

  Therefore, when the same angle of view is observed with the right eye 101 and the left eye 102, the way in which aberrations occur in the eyepiece optical system differs from left to right, and the difference between the left and right in terms of resolution and distortion is large. The image is difficult to image and cannot be viewed stereoscopically, or fatigue during observation increases.

  As can be seen from FIG. 1, the left side of the right-eye eyepiece optical system 103 and the right side of the left-eye eyepiece optical system 104 according to the present embodiment have a shape obtained by cutting the lens. The ocular eyepiece optical system 104 is different. This is to eliminate the optical system other than the effective region of the light beam, thereby reducing the size and weight of the optical system and avoiding interference between the left and right optical systems on the inside. Furthermore, since the inner optical system can be made small, it is possible to provide an image display device that does not easily hit the observer's nose, and comfortable observation is possible.

  When the right eyepiece optical system 113 and the left eyepiece optical system 114 remain in a lens shape and do not cut other than the light effective area as in the conventional example of FIG. 3, the left and right optical systems interfere inside, An optical system cannot be arranged. For this reason, it is necessary to narrow the angle of view to be displayed, and an image display device having a wide angle of view cannot be realized.

  FIG. 4A shows how an image looks when a video with a different angle of view is displayed on the left and right eyes and only a part of the angle of view is overlapped with the left and right eyes as in the present embodiment. The image displayed on the right-eye display element 105 and the image displayed on the left-eye display element 106 are combined, and images of the left eye region, the binocular region, and the right eye region are observed. At this time, the boundary between the left eye region and the binocular region, and the right eye region and the binocular region are observed as shown in FIG. Although an image is displayed on one eye, an image is not displayed on the other eye, and a black portion such as a frame of the panel is seen, which is caused by a visual field struggle between the left and right eyes.

  Therefore, as shown in FIG. 5, the left side of the right-eye eyepiece optical system 115 is made narrower than the effective ray region of the light beam guided from the display element 105 to the right eye 101, and the right side of the left-eye eyepiece optical system 116 is shown on the display element 106. The beam may be made narrower than the effective ray region of the light beam guided to the left eye 102. By doing so, the light beam from the boundary between the monocular region and the binocular region does not enter the optical system, and the light beam near the boundary is vignetted by the optical system, so the boundary is as shown in FIG. Can be prevented from being observed.

  Although the eyepiece optical system of the present embodiment is configured by a single spherical lens, it may be an aspherical lens or a lens having higher optical performance by using a plurality of lenses. In addition, the display element of this embodiment uses a self-luminous organic EL, but a transmissive liquid crystal, a reflective liquid crystal, a DMD, or the like may be used as the display element. In that case, a separate light source and illumination optical system are required.

  When observing an image with parallax on the left and right with the image display device of the present embodiment, the shape of the surface of the optical system through which light passes when observing the same angle of view is not exactly the same between the left and right eyepiece optical systems. . However, since the difference in the shape of the surface on the left and right is small compared to the image display device of FIG.

(Second Embodiment)
The configuration of the image display apparatus according to the second embodiment will be described with reference to the top view of the image display apparatus of FIG. In the figure, 201 is an observer's right eye, 202 is an observer's left eye, 203 is an eyepiece optical system for the right eye, 204 is an eyepiece optical system for the left eye, 205 is a display element for the right eye, and 206 is for the left eye. A display element, 207 is a right eye visual axis, and 208 is a left eye visual axis. The right eye visual axis 207 and the left eye visual axis 208 are parallel.

  The right eyepiece optical system 203 enlarges the right eye display element 205 and leads it to the observer's right eye 201, and the left eye eyepiece optical system 204 enlarges the left eye display element 206 to the observer's right eye 201. Guide to the left eye 202. The center of the right-eye display element 205 is shifted to the right with respect to the vertical section including the right-eye viewing axis 207, and the display field angle of the right-eye eyepiece optical 203 is 40 ° on the right side and 30 ° on the left side. The center of the left-eye display element 206 is shifted to the left with respect to the vertical section including the left-eye viewing axis 208, and the display angle of view of the left-eye eyepiece optical system 204 is 30 ° on the right side and 40 ° on the left side. The angles of view displayed by the left and right eyepiece optical systems are different from each other. Therefore, when the observer observes with both eyes, the right side 40 ° to the right side 30 ° is observed only with the right eye, the right side 30 ° to the left side 30 ° is observed with both eyes, and the left side 30 ° to the left side 40 °. Until then, observation is performed only with the left eye, and the entire horizontal angle of view is 80 °. In this way, images with different angles of view are displayed on the left and right eyes so that only a part of the angle of view overlaps with the left and right eyes. It is possible to observe an image with a wider angle of view than when displaying the video.

In the present embodiment, among the observation images of the right eye, the binocular region has an angle of view of 60 ° and the right eye region has an angle of view of 10 °, and the observation image of the right eye region with respect to the area of the observation image of the binocular region is The area ratio is 23% according to the equation (2).
(Tan (40 °) −tan (30 °)) / (2 × tan (30 °)) = 0.23 Formula (2)
This ratio is desirably 45% or less. When the ratio is greater than 45%, the boundary between the binocular region and the monocular region comes near the center of the observation image, and thus the boundary is easily noticeable. In addition, since the ratio of the binocular region is small, the region that can be stereoscopically viewed is narrow, and natural stereoscopic observation is not possible. Further, this ratio is desirably 10% or more. When the ratio is smaller than 10%, the monocular region is narrowed and the effect of widening the angle of view is small. The same applies to the observation image of the left eye.

  The eyepiece optical system of the present embodiment has a reduced optical system thickness by folding the optical path using an eccentric reflection curved surface. The eyepiece optical system 203 for the right eye and the eyepiece optical system 204 for the left eye are constituted by a transparent body filled with an optical medium such as glass or plastic having a refractive index greater than 1.

  FIG. 7 is a side view of the eyepiece optical system 203 for the right eye. Light rays from the right-eye display element 205 are reflected twice in the right-eye eyepiece optical system 203 and guided to the right eye 201. Since the exit surface to the eyeball in the right eyepiece optical system 203 is a surface having reflection and transmission functions, it is desirable that the reflection is total internal reflection in order to eliminate a loss of light amount. Similarly for the left-eye eyepiece optical system 204, the light beam from the left-eye display element 206 is reflected twice in the left-eye eyepiece optical system 204 and guided to the left eye 202. Since the exit surface to the eyeball in the left-eye eyepiece optical system 204 is a surface having reflection and transmission functions, it is desirable that the reflection is total internal reflection in order to eliminate a loss of light amount.

  The observer-side surfaces of the right-eye eyepiece optical system 203 and the left-eye eyepiece optical system 204 of the present embodiment are free-form surfaces represented by the same function, and the display element-side surface and the reflective surface are also right-hand. The eyepiece optical system 203 for the eye and the eyepiece optical system 204 for the left eye are free-form surfaces represented by the same function. Therefore, all the optical surfaces of the right-eye eyepiece optical system 203 have the same optical power as the optical surfaces of the left-eye eyepiece optical system 204 having the same positional relationship as the respective optical surfaces.

  In addition, the shape of all optical surfaces of the right-eye eyepiece optical system 203 is expressed by a shape that is symmetric with respect to a vertical section including the right-eye viewing axis 207. Similarly, the shapes of all the optical surfaces of the left-eye eyepiece optical system 204 are expressed in a symmetrical shape with respect to a vertical section including the left-eye visual axis 208.

  Therefore, when the same angle of view is observed by the right eye 201 and the left eye 202, the shape of the surface of the optical system through which light rays of the angle of view pass is the same in the left and right eyepiece optical systems, and thus occurs in the eyepiece optical system. Aberrations are the same on the left and right. As a result, there is almost no difference between the right and left in the resolution and distortion, and the image is easily fused with both eyes. Further, by making the surfaces constituting the right eyepiece optical system 203 and the left eyepiece optical system 204 into a free-form surface, the degree of freedom in correcting decentration aberrations can be increased, and an image can be displayed with good image quality. .

  As can be seen from FIG. 6, the left side of the right-eye eyepiece optical system 203 and the right side of the left-eye eyepiece optical system 204 of the present embodiment have a shape obtained by cutting a prism. The eyepiece optical system 204 is different. This is to eliminate the optical system other than the effective region of the light beam, thereby reducing the size and weight of the optical system and avoiding interference between the left and right optical systems on the inside. Furthermore, since the inner optical system can be made small, it is possible to provide an image display device that does not easily hit the observer's nose, and comfortable observation is possible.

  Here, the light ray effective area of the surface on the display element side of the eyepiece optical system is equal to the size of the display element, and the light ray effective area of this surface is determined as the light ray effective area of the right eyepiece optical system 203 and the eyepiece eye optics for the left eye. Even the region including the effective ray region of the system 204 does not affect the size of the eyepiece optical system. Therefore, the light ray effective areas of the display element side surfaces of the right eyepiece optical system 203 and the left eyepiece optical system 204 may be equal. By doing so, the left and right optical systems can have the same shape and the same light effective area, and processing and fabrication can be facilitated.

  When displaying images with different angles of view on the left and right eyes and overlapping only a part of the angles of view with the left and right eyes as in this embodiment, the left eye region, the binocular region, and the right eye region And the boundary of the binocular region becomes conspicuous. Therefore, as shown in FIG. 8, the left side of the right eyepiece optical system 209 is made narrower than the light beam effective area of the light beam guided from the display element 205 to the right eye 201, and the right side of the left eyepiece eyepiece optical system 210 is shown on the display element 206. May be narrower than the light beam effective area of the light beam guided to the left eye 202. By doing so, the light beam from the boundary between the monocular region and the binocular region does not enter the optical system, and the light beam near the boundary is vignetted by the optical system, so that the boundary is less noticeable.

  Further, the reflective surfaces of the right eyepiece optical system 203 and the left eyepiece optical system 204 are vapor-deposited so that the reflectances of the reflective films are equal as shown in FIG. This reflective film lowers the reflectance of the portion where the light flux from the boundary between the monocular region and the binocular region is reflected, such as the right-eye eyepiece optical system 211 and the left-eye eyepiece optical system 212 in FIG. 9B. A reflective film with gradation may be used. By doing in this way, since the light flux from the boundary part of a monocular area | region and a binocular area | region becomes difficult to be reflected by a reflective surface, a boundary part becomes difficult to stand out.

101 (201) Right eye of observer 102 (202) Left eye of observer 103 (115, 203, 209, 211) Eyepiece optical system for right eye 104 (116, 204, 210, 212) Eyepiece optical system for left eye 105 (205) Right-eye display element 106 (206) Left-eye display element 107 (207) Right-eye visual axis 108 (208) Left-eye visual axis

Claims (9)

Two display elements corresponding to the left and right eyes of the observer,
An eyepiece optical system for the left eye and an eyepiece optical system for the right eye for guiding the image of the display element to the left and right eyes of the observer,
The optical power of the optical surface of the left eyepiece optical system for the left eye of the observer is the same as the optical power of the right eyepiece optical system for the right eye of the observer,
The shape of the optical surface of the left-eye eyepiece optical system is bilaterally symmetric with respect to a vertical section including the visual axis of the left eye of the observer,
The shape of the optical surface of the right eyepiece eyepiece optical system is bilaterally symmetric with respect to a vertical section including the visual axis of the right eye of the observer.   The image display device according to claim 1, wherein the left eyepiece optical system and the right eyepiece optical system are partially different in shape.   The image display apparatus according to claim 1, wherein the image displayed on the display element includes a binocular region and a monocular region different from the binocular region. The right ray effective area of at least one surface of the eyepiece optical system for the left eye is smaller on the right side than the left side with respect to the visual axis of the left eye when viewed from the left eye,
The left side of the right eye effective area of the eyepiece optical system for the right eye is smaller than the right side with respect to the visual axis of the right eye when viewed from the right eye. 4. The image display device according to any one of items 3. The center of the display element for the left eye is shifted to the left with respect to a vertical section including the visual axis of the left eye when viewed from the left eye;
The center of the display element for the right eye is shifted to the right with respect to a vertical section including the visual axis of the right eye when viewed from the right eye. The image display device according to item. The eyepiece optical system for the left eye prevents the light flux from the boundary between the binocular region and the monocular region from entering or exiting the eyepiece optical system for the left eye. The light effective area is narrower than the light effective area of the light beam guided from the left eye display element to the left eye,
The eyepiece optical system for the right eye prevents the light beam from the boundary between the binocular area and the monocular area from entering or exiting the eyepiece optical system for the right eye. The image display apparatus according to claim 3, wherein a light ray effective area is narrower than a light ray effective area of a light beam guided to the right eye from the display element for the right eye.   7. The left-eye eyepiece optical system and the right-eye eyepiece optical system are prisms having an optical surface having a transmission and reflection action and at least one reflection surface. The image display device according to any one of the above.   The reflectance of the first reflecting surface of the left-eye eyepiece optical system is smaller on the right side than the left side when viewed from the left eye, and the reflection on the second reflecting surface of the right-eye eyepiece optical system The image display device according to claim 7, wherein the rate is smaller on the left side than on the right side when viewed from the right eye.   4. The image display device according to claim 3, wherein the image displayed on the display element has an area of the monocular region with respect to an area of the binocular region of 10% or more and 45% or less. 5. .