JP2018189784A - Image observation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image observation device that can present, to an observer, an outside world image having a wide angle of view and high geometric reproducibility, despite its small size and light weight.SOLUTION: An image observation device comprises: an imaging system that picks up an image of an outside world; image display means 102 that displays an outside world image acquired from the imaging system; and a display optical system 101 that guides a display light bundle from the image display means to an exit pupil 201. The imaging system includes a plurality of cameras that picks up optical images formed respectively by imaging optical systems 105 and 107 with imaging elements 104 and 106, and a reflection optical system 110 that reflects an incident light bundle from the outside world to be guided to the plurality of cameras. Entrance pupils 200 of the respective imaging optical systems of the plurality of cameras are at positions both moved through reflection of the reflection optical system from the same space positions 201'. The reflection optical system has a plurality of reflection surfaces 110s that reflect incident light bundles from a plurality of viewing angle areas in the outside world to be guided to the plurality of cameras.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a camera that images the outside world and an image observation apparatus that presents an image acquired by the camera to an observer's eye through a display optical system.

  Mixed reality (MR: Mixed Reality) technology and augmented reality (AR: Augmented Reality) technology are known as technologies that fuse the real world (external world) and the virtual world in real time. These MR and AR technologies use a video see-through HMD (Head-Mounted Display). As disclosed in Patent Document 1, this video see-through type HMD acquires a real-world image with a video camera, superimposes a virtual space image (CG image or the like) on the image, and displays the superimposed image. Presented to the observer through the display optics. In such a video see-through type HMD, in order to improve the geometric reproducibility of the image observed by the observer, the position of the entrance pupil of the camera and the position of the observer's pupil (exit pupil of the display optical system) are shifted. It is desirable that the number be as small as possible.

Japanese Patent No. 3604990

  In video see-through HMDs, it is often necessary to place a video camera on the outside of the display optical system in front of the viewer's eyes. In this case, in order to reduce the deviation between the position of the entrance pupil of the video camera and the position of the observer's pupil, it is necessary to bend the optical path of the imaging optical system by the reflection optical system including the reflection surface.

  However, when the display optical system is large or the position of the entrance pupil of the video camera is brought closer to the position of the observer's pupil, the bent optical path needs to be lengthened. As a result, the reflective optical system is enlarged, and the overall size, weight, and increase of the HMD are increased.

  The present invention provides an image observation apparatus that is capable of presenting an observer with a wide field angle and high geometric reproducibility, while being small and light.

  An image observation apparatus according to one aspect of the present invention includes an imaging system that images the outside world, an image display unit that displays an outside world image acquired by the imaging system, and a display that guides display light flux from the image display unit to an exit pupil And an optical system. The imaging system includes a plurality of cameras that each capture an optical image formed by the imaging optical system with an imaging element, and a reflection optical system that reflects incident light from the outside and guides the light to the plurality of cameras. The entrance pupils of the imaging optical systems of the plurality of cameras are at positions moved from the same spatial position by the reflection of the reflection optical system. The reflective optical system has a plurality of reflecting surfaces that reflect incident light beams from a plurality of field angle regions in the external environment and guide them to a plurality of cameras.

  According to the present invention, it is possible to realize a small and lightweight image observation apparatus capable of presenting an external image having a wide angle of view and high geometric reproducibility to an observer.

The figure which shows the structure of the video see-through type HMD which is Example 1 of this invention. FIG. 5 is another diagram illustrating the configuration of the HMD according to the first embodiment. The figure which shows the video see-through HMD which does not use a bending | flexion optical system. The figure which shows the video see-through HMD using only one mirror. FIG. 3 is a diagram for explaining numerical conditions in the first embodiment. The figure which shows the structure of the video see-through type HMD which is Example 2 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a configuration of a video see-through HMD as an image observation apparatus that is Embodiment 1 of the present invention. This figure shows a vertical section through the center of the eyeball 103 of the observer. That is, the observer's eyes are arranged in a direction perpendicular to the paper of FIG. 1, and the configuration shown in FIG. 1 is provided for each eye. In FIG. 1, the visual axis direction of the observer's eyeball 103 is the + Z direction, and the + X direction (the front side of the paper in FIG. 1) and the + Y direction (upward direction) in the horizontal and vertical directions orthogonal to the + Z direction, respectively. And

  Reference numeral 101 denotes a display optical system, which is a prism composed of three optical surfaces each having power, and presents an enlarged virtual image of an image displayed on an image display element described later to an observer. The display optical system 101 in this embodiment is a decentered optical system, and is decentered within the vertical cross section shown in FIG. However, this display optical system 101 is only an example, and may have any configuration as long as it is an optical system that can present an enlarged virtual image to an observer.

  The image display element (image display means) 102 is configured by a liquid crystal panel or an organic EL panel. However, instead of the image display element, a device that displays an image to an observer by combining a laser light source and a scanning device may be used.

  FIG. 1 shows only a plurality of principal rays of the display light beam that is emitted from the image display element 102 and passes through the display optical system 101 and reaches the pupil of the observer 103. The observer visually recognizes an enlarged virtual image of the image (video) displayed on the image display element 102 by arranging the pupil of the eyeball 103 at the point where these principal rays intersect, that is, the position of the exit pupil of the display optical system 101. be able to.

  Reference numeral 105 denotes a first image pickup optical system, which condenses an incident light beam from the first field angle region (upper field angle region) in the outside world where the subject actually exists on the image pickup surface of the first image sensor 104. Let me image. Reference numeral 107 denotes a second imaging optical system that forms an incident light beam from the second field angle region (lower field angle region) in the outside world on the imaging surface of the second image sensor 106. The first and second imaging optical systems 105 and 107 are optical systems having the same configuration. The first and second imaging elements 104 and 106 are constituted by photoelectric conversion elements such as CMOS sensors and CCD sensors, and the first and second images formed by the first and second imaging optical systems 105 and 107. Photoelectric conversion (imaging) of the optical image in the corner region.

  The first and second imaging optical systems 105 and 107 and the first and second imaging elements 104 and 106 constitute an imaging system. Further, the first imaging optical system 105 and the first imaging element 104 constitute a first camera, and the second imaging optical system 107 and the first imaging element 106 constitute a second camera. In this embodiment, two cameras are used, but a plurality of three or more cameras may be used.

  Reference numeral 110 denotes a main mirror having two reflection surfaces 110s arranged in a V shape, and constitutes a bending optical system (reflection optical system) that divides the outside world into first and second field angle regions. The two reflecting surfaces 110s correspond to first reflecting surfaces arranged on the outermost side (subject side) of the bending optical system. These reflecting surfaces 110s reflect incident light beams from the first and second field angle regions of the outside world in opposite directions (upward and downward directions). The main mirror 110 may be an integral type or a combination of two mirror members as long as it has two reflecting surfaces. The first and second cameras and the main mirror 110 constitute an imaging system.

  Reference numeral 108 denotes a central field angle chief ray that reaches the center of the imaging surface of the first and second imaging elements 104 and 106 through the center of the external field angle captured by the first and second cameras in the incident light flux. . The two reflecting surfaces of the first and second cameras and the main mirror 110 are arranged so as to be vertically symmetrical with respect to the central field angle principal ray 108 incident from the outside world. The optical specifications are the same. For this reason, the field angles of the first and second field angle regions captured by the first and second cameras via the main mirror 110 are the same. In addition, the direction of the central field angle principal ray 108 from the outside to the main mirror 110 is the center field angle principal ray from the display optical system 101 to the observer's eyeball 103 (from the center of the display surface of the image display element 102 to the display optical system). The direction of the light beam 109 going to the center of the exit pupil via 101 is the same as that 109. Then, the first video and the second video acquired by imaging by the first and second cameras are combined vertically (connected) and displayed on the image display element 102. Thereby, an external world image (external world image) as a composite image having a wide angle of view corresponding to the external world viewed from the position of a virtual entrance pupil 200 'described later can be presented to the observer.

  In addition, it is desirable that the combined planned angle of the first and second field angle regions in the outside world is at least equal to or larger than the field angle of the display optical system. That is, when the half field angle in the eccentric direction of the display optical system 101 shown in FIG. 1 is ω1, and each field angle of the first and second cameras is ω2, ω1 ≦ ω2 (more preferably, ω1 <Ω2, more preferably ω1 × 1.1 <ω2.) Thereby, the observer can view an external image with an appropriate size feeling by appropriately adjusting the captured external field angle. In the MR technique and the AR technique, an image obtained by superimposing a virtual image such as a CG image on the external image as a real image is presented to an observer.

  FIG. 2 shows the position of the virtual entrance pupil 200 ′ that is the effective viewpoint of the first and second cameras (first and second imaging optical systems 105 and 107) in the same eccentric section as FIG. . The first and second cameras have a virtual entrance pupil 200 ′ at the same spatial position. In other words, the actual entrance pupil 200 of each of the first and second imaging optical systems 105 and 107 is at a position moved by reflection of the bending optical system from the same spatial position (virtual entrance pupil 200 '). . It should be noted that the same spatial position includes a case where there is a shift of an error such as a manufacturing error.

  A pupil shift amount D which is a difference between the position of the exit pupil 201 of the display optical system 101 where the pupil of the eyeball 103 of the observer is located and the position of the virtual entrance pupil 200 ′ of the first and second imaging optical systems 105 and 107. Is preferably as small as possible. The virtual entrance pupil 200 ′ in FIG. 2 has an exit pupil (201 than the display optical system 101, even though the first and second cameras are arranged on the outside world side (subject side) with respect to the display optical system 101. ) Side. Thereby, the observer can observe an external image with high geometric reproducibility.

  When the bending optical system as in this embodiment is not used, as shown in FIG. 3, the camera is arranged in front of the display optical system 101. In this case, the entrance pupil of the imaging optical system of the camera is used. 202 is located on the outside side of the display optical system 101. Accordingly, the pupil shift amount D ′ is larger than the pupil shift amount D of the present embodiment.

  4 shows a configuration example in which the same pupil shift amount D ″ as in the present embodiment is realized with only one mirror 301. In this case, the size of the mirror 301 increases the size of the entire HMD, and Since the observer wears the HMD on the head, it is desirable that the size and weight of the HMD be as small as possible.

  As can be seen from the above, according to the present embodiment, it is possible to realize a video see-through type HMD that is capable of presenting a wide-angle external field image to an observer while being small and light.

  Hereinafter, with reference to FIG. 5, conditions that are preferably satisfied with respect to the arrangement of the first and second cameras and the main mirror 110 will be described. FIG. 5 shows the imaging optical system (105, 107) of one of the first and second cameras shown in FIG. 1 and the reflecting surface 110s of the imaging elements 104, 016 and the main mirror 110. Yes.

  In FIG. 5, the angle of view of the camera (imaging optical system) in the eccentric section (YZ section) where the optical path of the incident light beam is bent by reflection at the reflecting surface 110s is ω2 (deg), and the eccentricity of the reflecting surface 110s in the eccentric section. Let the angle be θ (deg). Further, the distance from the reflecting surface 110s on the central field angle principal ray 108 incident on the camera to the actual entrance pupil 200 of the imaging optical system is L (mm), and the radius of the entrance pupil 200 is r (mm). . Further, e (mm) is a distance from the first surface closest to the bending optical system (reflection optical system) of the imaging optical system to the entrance pupil 200. At this time, in order that the incident light beam 140 from at least the direction of the field angle ω2 does not interfere with the imaging optical system after being reflected by the reflecting surface 110s, it is necessary to satisfy the condition expressed by the following expression (1).

Numerical examples of this embodiment are shown below.
ω1 = 20 (deg)
ω2 = 25 (deg)
L = 40 (mm)
θ = 45 (deg)
r = 0.5 (mm)
e = 0.0 (mm).
In this numerical example, equation (1) is

Thus, the condition of formula (1) is satisfied. Thereby, it is possible to realize an arrangement without interference (vignetting) of the optical path.

  FIG. 6 shows the configuration of a video see-through HMD that is Embodiment 2 of the present invention. This figure also shows an eccentric cross section as in FIG. The meanings of the + Z direction, + X direction, and + Y direction are the same as those in the first embodiment. Similarly to the first embodiment, the HMD of the present embodiment also includes the image display element 402, the display optical system 401, the first camera (the first imaging optical system 405 and the first imaging element 404), and the second camera ( A second imaging optical system 407, a second imaging element 406), and a bending optical system 410;

  However, in this embodiment, the length of the optical path bent by the bending optical system is made longer than that of the first embodiment in order to set the above-described pupil shift amount D to zero. That is, a distance L (from the reflection surface (first reflection surface) 410s on the central field angle principal ray 108 incident on each of the first and second cameras to the actual entrance pupil 400 of the imaging optical system of the camera. mm) is lengthened. In order to realize this in a compact configuration, not only the main mirror having the two reflecting surfaces 410s in the bending optical system, but also two reflecting surfaces (second mirrors) as sub-mirrors for further reflecting and folding the optical path. 2 reflective surfaces) 431 and 432 are provided. In other words, a plurality of (two in this embodiment) reflecting surfaces are provided for each of the first and second melas. This realizes a compact HMD while increasing the optical path length from the entrance to the bending optical system to the entrance pupil 400 of each of the first and second cameras. In addition, since the position of the exit pupil 501 of the display optical system 401 and the position of the virtual entrance pupil 400 ′ of the first and second imaging optical systems 405 and 407 coincide with each other, the observer has geometric reproducibility. However, it is possible to observe a higher external image than in the first embodiment.

In this embodiment, the imaging element 406 is positioned on the exit pupil side from the end 410e closest to the exit pupil (501) in the optically effective area of the bending optical system by bending the optical path by the reflecting surfaces 431 and 432. Yes. Thereby, the size of the entire HMD can be further reduced.
Numerical examples of this embodiment are shown below.
ω1 = 20 (deg)
ω2 = 22 (deg)
L = 70 (mm)
θ = 55 (deg)
r = 0.5 (mm)
e = 1.0 (mm)
In this numerical example, the value of equation (1) is

Thus, the condition of formula (1) is satisfied. Thereby, it is possible to realize an arrangement without interference (vignetting) of the optical path.

  In the present embodiment, the case where the optical path toward each camera is bent using two reflecting surfaces has been described, but three or more reflecting surfaces may be used. That is, the number is not limited as long as each camera has one or more reflecting surfaces.

  Each embodiment described above is only a representative example, and various modifications and changes can be made to each embodiment in carrying out the present invention.

101, 401 Display optical systems 102, 402 Image display elements 104, 106, 404, 406 Imaging elements 105, 107, 405, 407 Imaging optical systems 110, 410 Main mirrors 200, 400 Entrance pupils 201, 501 (of the imaging optical system) Exit pupils 431 and 432 (display optical system)

Claims (6)

An image observation apparatus comprising: an imaging system that images the outside world; an image display unit that displays an outside world image acquired by the imaging system; and a display optical system that guides a display light beam from the image display unit to an exit pupil,
The imaging system includes a plurality of cameras that capture images of optical images formed by the imaging optical systems, respectively, and a reflection optical system that reflects incident light from the outside and guides the plurality of cameras to the cameras.
The entrance pupil of the imaging optical system of each of the plurality of cameras is at a position moved by reflection of the reflective optical system from the same spatial position,
The image observation apparatus according to claim 1, wherein the reflection optical system includes a plurality of reflection surfaces that reflect incident light beams from a plurality of angle-of-view areas in the external environment and guide the light beams to the plurality of cameras.   The image observation apparatus according to claim 1, wherein the reflection optical system reflects the incident light flux in opposite directions.   3. The image observation apparatus according to claim 1, wherein each of the plurality of cameras has at least one reflection surface including the first reflection surface arranged closest to the outside world. 4. . The half angle of view of the display optical system in the eccentric section where the optical path of the incident light beam is bent by reflection on the reflecting surface is ω1 (deg), and the field angles of the plurality of cameras in the eccentric section are ω2 (deg). )
ω1 ≦ ω2
The image observation apparatus according to claim 1, wherein the following condition is satisfied. The angle of view of each of the plurality of cameras in an eccentric cross section where the optical path of the incident light beam is bent by reflection at the reflecting surface is ω2 (deg), and the central field angle principal ray incident on each of the plurality of cameras is The eccentric angle of the first reflecting surface is θ (deg), the distance from the first reflecting surface to the entrance pupil on the central field angle principal ray is L (mm), and the radius of the entrance pupil is r. (Mm) and when the distance from the first surface closest to the reflective optical system to the entrance pupil of the imaging optical system is e (mm),

The image observation apparatus according to claim 1, wherein the following condition is satisfied.   6. The image observation apparatus according to claim 1, wherein the imaging element is located closer to the exit pupil than an optically effective area of the plurality of reflecting surfaces.