JPH07287188A - Optical system for hmd - Google Patents

Abstract

PURPOSE:To provide an optical system for HMD which is usable for an HMD of a type equipped with one display device and generates no defocusing even when eye width is adjusted. CONSTITUTION:A 1st relay system RL1 has its front focus F1 positioned at the position of an original image IO, so luminous flux from the image IO is made by the RL1 into parallel luminous flux, which is split into two by a half- mirror 4 to impinge on a 2nd relay system RL2 (5L and 5R). Secondary images IL and IR are observed through oculars 8L and 8R, but the 2nd relay system RL2 has its rear focuses F2L and F2R positioned at the positions of the secondary images IL and IR, so the secondary images IL and IR do not shift in position as to the pupils ER and EL even when the interval between the half-mirror 4 and relay lens 5R for the right eye is varied for the eye width adjustment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an HMD optical system, and more particularly to a binocular type HMD optical system.

[0002]

2. Description of the Related Art Recently, a built-in LCD (liquid crystal displa) can be worn on the face like a helmet or goggles.
y), a so-called head mounted display (HMD) that can observe image information from a display device such as a CRT (cathode-ray tube) through an eyepiece has been widely announced. It is expected to grow more and more in the future because it is more portable than conventional display devices, and both hands are free.

HMDs that have been conventionally announced have a type in which image information is shown only to one eye (a one-eye type; for example, Virtual Vision Sports manufactured by Virtual Vision Co.) and a type in which image information is shown to both eyes ( Binocular type). The one-eye type HMD is advantageous in terms of compactness, cost, etc., but the binocular type HMD is more advantageous in terms of ease of viewing and fatigue resistance.

This binocular type HMD is further equipped with two sets of display devices (LCD, CRT, etc.) (for left eye and right eye) (Japanese Patent Laid-Open No. 6-46355, US Pat. No. 2,953).
No. 5,156, Sony Visortron, Olympus Face Mounted Display, etc.) and a set of display devices, and the light from one original image formed by the display device by dividing the optical path It is classified into a type that leads to the left and right eyes (US Pat. No. 4,902,116 etc.).

By the way, what becomes a problem when observing image information with both eyes is the individual difference in the distance between the left and right eyes of the user. As one method for dealing with the distance between the left and right eyes of various users, there is a method of providing an adjusting mechanism for changing the distance between the left and right eyepieces. For example, in binoculars and binocular microscopes, the distance between the left and right eyepieces is usually changed by rotating the left and right eyepieces around an axis that is positioned parallel to the optical axis of the eyepiece lens. It is called "eye distance adjustment").

A type having two sets of display devices (for example, L
In the type using two CDs), basically, the left and right observation optical systems can be configured only by the display device and the eyepieces, so that there is an advantage that the configuration of the observation optical system can be simplified. . For example, the observation optical system can be easily combined into a left eye unit and a right eye unit. If the observation optical system is unitized in this way,
Interpupillary adjustment can be done simply by changing the distance between the units. However, since display devices such as LCDs and CRTs are generally expensive, the type having one set of display devices is more advantageous in terms of cost.

Here, a conventional HMD of the type including one set of display devices will be described with reference to FIG. Original image (not shown) displayed on the display device 1 (LCD in this case)
Is reflected by the reflection mirrors 2-1 and 2-2 and enters the relay lens 3. Here, the reflection mirrors 2-1 and 2-1
-2 is arranged to reduce the size of the entire optical system, and is not always necessary.

A part of the light passing through the relay lens 3 is reflected by the half mirror 4 and further reflected by the reflecting mirror 6R toward the pupil ER of the right eye. Then, the secondary image (not shown) of the original image is the secondary image plane SR for the right eye.
Imaged in position. The formed secondary image is observed by the user through the eyepiece lens 8R for the right eye. On the other hand, part of the light passing through the relay lens 3 passes through the half mirror 4,
It is reflected toward the pupil EL of the left eye by the reflecting mirrors 6L and 7L. Then, the secondary image (not shown) of the original image is formed at the secondary image plane SL position for the left eye. The formed secondary image is observed by the user through the eyepiece lens 8L for the left eye. The eyepieces 8L and 8R are movable in the front-rear direction so as to be compatible with myopia and hyperopia.

[0009]

From FIG. 6, it is the reflection mirror 6 that determines the distance between the left and right eyes (that is, the lateral distance from the pupil EL to the eye ER) in the conventional example.
It can be seen that the distance is between R and the reflection mirror 7L. Therefore, in order to perform the interpupillary distance adjustment, it is necessary to adopt the following methods (1) to (3).

A portion of the optical system relating to the optical path for the right eye (that is, the reflection mirror 6R, the secondary image surface SR, and the eyepiece 8R) is moved in the left-right direction (for example, when the eye width is widened) toward FIG. To the right). : A part of the optical system related to the optical path for the left eye (that is, the reflection mirror 7L, the secondary image surface SL, and the eyepiece 8L) is moved in the left-right direction toward the direction of FIG. Direction). : Do at the same time.

Consider a case where the interpupillary distance is adjusted by the method. The length measured from the relay lens 3 to the secondary image plane SR along the optical axis XR after the optical path division is the length measured from the display device 1 to the relay lens 3 along the optical axis X before the optical path division and the relay. It depends on the focal length of the lens 3. Display device 1 along optical axis X before optical path division
From relay lens 3 to relay lens 3
Since both focal lengths are constant, the length measured from the relay lens 3 to the secondary image plane SR along the optical axis XR after the optical path division is also constant.

Therefore, when the optical system for the right eye (that is, the reflecting mirror 6R and the eyepiece 8R) is moved rightward, the distance between the half mirror 4 and the reflecting mirror 6R becomes wide, but
The distance between the reflection mirror 6R and the secondary image surface SR becomes narrow. Conversely, if you move the optical system for the right eye to the left,
Although the distance between the half mirror 4 and the reflection mirror 6R becomes narrower, the distance between the reflection mirror 6R and the secondary image surface SR becomes wider.

When the distance between the reflecting mirror 6R and the reflecting mirror 7L is changed to adjust the pupil distance, the reflecting mirrors 6R and 2L
As a result of the change in the distance from the next image surface SR, defocus occurs. In order to eliminate the focus shift, the diopter must be adjusted again by moving the eyepiece lens 8R in the front-back direction. For example, in FIG.
As shown in, when the optical system for the right eye is moved to the right, it is necessary to perform the diopter adjustment again by moving the eyepiece lens 8R forward.

As described above, the configuration in which the interpupillary distance adjustment is performed by the above method has a problem that the operation becomes troublesome because the observation optical system is not independent on the left and right. Further, since the left and right eyepieces 8L and 8R are largely displaced in the front-rear direction, there is a problem that it becomes difficult to look through and vignetting occurs in the visual field. Even when the interpupillary distance adjustment is performed by the above method, the same problem as this occurs.

When the method (1) is adopted, the optical system for the left eye (that is, the reflection mirror 7L, the eyepiece 8L) and the optical system for the right eye (that is, the reflection mirror 6R, the eyepiece 8R) are If the eyepieces 8L and 8R are moved by the same amount, there will be no displacement between the front and rear. However, it is the same as when the method of (2) is adopted that the diopter adjustment has to be performed again. In addition, there is a problem that the structure becomes complicated and the number of movable parts increases, so that there is a higher possibility that the left and right optical axis shifts occur.

By the way, as another method for dealing with the distance between the left and right eyes of various users, there is a method of increasing the exit pupil diameter from the eyepiece lens. If the exit pupil diameter from the eyepieces 8L and 8R is made sufficiently larger than the variation in the distance between the left and right eyes, it is possible to cope with various pupil distances without the pupil distance adjusting mechanism. However, in order to cover the range in which the eye width of most people falls (that is, the eye width range of 60 to 70 mm), the exit pupil diameter must be at least φ5 mm or more. for that purpose,
It is necessary to increase the lens diameter and perform aberration correction corresponding to a large pupil. For example, if the focal length of the eyepiece lens is 20 mm, the eyepiece lens is a brighter lens than F _No. = 4, and it becomes difficult to correct each aberration such as spherical aberration, field curvature, and distortion aberration. . In order to correct aberrations as needed, there arises a problem that the number of lenses must be increased.

The present invention has been made in view of these points, and it can be used for an HMD of the type having one set of display devices, and an HMD that does not cause a focus shift even if the interpupillary adjustment is performed. The purpose is to provide an optical system for use.

[0018]

In order to achieve the above object, an optical system for an HMD according to a first aspect of the present invention divides an optical path to divide an optical path from one original image into two optical paths. Splitting means and 2 of the original image
A binocular HMD optical system comprising a relay lens system for forming a secondary image, and two sets of eyepiece systems for respectively observing the two secondary images formed by the optical path splitting means and the relay lens system. The relay lens system includes a first relay system having a front focal point at the position of the original image and a second relay system having a rear focal point at the position of the secondary image. The optical path is divided between the first relay system and the second relay system.

The HMD optical system according to the second aspect of the present invention is an optical path splitting means for splitting a light beam from one original image into two light beams by splitting an optical path, and a secondary image of the original image. A relay lens system for focusing
Binocular type H consisting of an eyepiece system for observing images
In the MD optical system, the optical path splitting means is arranged in the vicinity of the original image, and the relay lens system includes a first relay system in which a front focal point is located at the position of the original image and a position of the secondary image. And a second relay system in which a rear focal point is located, and one of the light beams split by the optical path splitting means is used to form the secondary image, and the eyepiece lens system is configured to include the optical path splitting means. And a second eyepiece system for observing the secondary image formed by the relay lens system. .

[0020]

According to the HMD optical system of the first aspect of the present invention, the first relay system, which forms part of the relay lens system, has the front focal point located at the position of the original image. The light flux emitted from the first relay system becomes a parallel light flux. This parallel light flux is split into two light fluxes by the optical path splitting means, and is incident on the second relay system which is a part of the relay lens system. The secondary image formed by the relay lens system is observed by the eyepiece lens system, but since the rear focal point of the second relay system is located at the position of the secondary image, it is necessary to adjust the interpupillary distance. The position of the secondary image with respect to the pupil does not change even if the distance between the first relay system and the second relay system is changed. As a result, even if the interpupillary adjustment is performed, it is not necessary to move the eyepiece lens back and forth.

According to the HMD optical system of the second invention, the light beam from the original image is split into two light beams by the optical path splitting means arranged in the vicinity of the original image. The first eyepiece system directly observes the original image using one of the light beams split by the optical path splitting means. The other split light flux enters a first relay system forming a part of the relay lens system. Since the front focal point of the first relay system is located at the position of the original image, the first relay system forms a parallel light beam, which is incident on the second relay system and then imaged at the rear focal position of the second relay system. To do. The second eyepiece system observes the secondary image thus formed by the relay lens system, but since the rear focal point of the second relay system is located at the position of the secondary image, the interpupillary adjustment is performed. Even if the distance between the first relay system and the second relay system is changed in order to perform, the position of the secondary image with respect to the pupil does not change. As a result, even if the interpupillary adjustment is performed, it is not necessary to move the eyepiece lens back and forth.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical system for HMD according to an embodiment of the present invention will be described below with reference to the drawings. The same or corresponding parts as those of the conventional example (FIGS. 6 and 7) are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 is a top view of the first embodiment according to the present invention, and FIG. 2 is an optical path diagram for a light beam emitted from one point on the optical axis X of the display device 1. The first embodiment is a binocular type optical system for HMD, and mainly includes an optical path splitting unit including a half mirror 4 and a relay lens system including a first relay system RL1 and a second relay system RL2 (5L, 5R). When,
The eyepiece lens system includes two pairs of eyepiece lenses 8L and 8R.

As a pair of original image forming means used for the HMD, in this embodiment (the same applies to the second to fourth embodiments), the display device 1 composed of an LCD is used.
RT, an objective lens or the like may be used. The original image is L
In the case of a CD or CRT, the object image formed on the screen and formed by the objective lens becomes the original image.

The half mirror 4 splits the optical path to split the light flux from one original image IO formed by the display device 1 into two light fluxes. Since the division of the optical path is performed between the first relay system RL1 and the second relay system RL2, the luminous flux is split during the process of image formation by the first relay system RL1.

As shown in FIG. 2, the first relay system RL1
And the relay lens 5L for the left eye which constitutes the second relay system RL2 form the secondary image IL of the original image IO. This secondary image IL is formed at the secondary image plane SL position for the left eye by dividing the optical path at the half mirror 4 and bending the optical path at the reflecting mirrors 2, 6L, 7L.

On the other hand, the secondary image IR of the original image IO is formed by the first relay system RL1 and the relay lens 5R for the right eye which constitutes the second relay system RL2. The secondary image IR is formed at the secondary image surface SR position for the right eye by dividing the optical path at the half mirror 4 and bending the optical path at the reflecting mirrors 2 and 6R.

The eyepiece lens 8L for the left eye allows the user to observe the secondary image IL formed by the half mirror 4, the first relay system RL1, the relay lens 5L for the left eye, and the like.
On the other hand, the eyepiece 8R for the right eye allows the user to observe the secondary image IR formed by the half mirror 4, the first relay system RL1, the relay lens 5R for the right eye, and the like.

The first relay system RL1 is an original image IO.
The front focal point F ₁ is located at the position. In other words,
The display device 1 is arranged at the position of the front focus F ₁ of the first relay system RL1. Therefore, 1 on the original image IO
The light flux emitted from the point becomes a parallel light flux by passing through the first relay system RL1. For example, the optical axis X of the display device 1
As shown in FIG. 2, the light flux emitted from the upper one point is a parallel light flux parallel to the optical axis X between the first relay system RL1 and the second relay system RL2.

The focal length of the first relay system RL1 is f
_If it is set to ₁ , the light emitted from a point distant from the optical axis X by y ₁ 'is a parallel light flux forming an angle θ with the optical axis X calculated from the following equation (1). y ₁ '= f ₁ · tan θ …… (1)

After that, the optical path is divided by the half mirror 4 into the left eye and the right eye. In the present embodiment (FIGS. 1 and 2), of the two parallel light beams divided into two, the transmitted light is used for the left eye and the reflected light is used for the right eye. It is of course possible to use for the right eye and use the reflected light for the left eye.

The relay lens 5L for the left eye has a secondary image IL
The rear focal point (image side focal point) F at the secondary image plane SL position where
It is arranged so that _2L is located. Therefore, when the parallel light flux for the left eye after passing through the half mirror 4 is incident on the relay lens 5L for the left eye, the secondary image IL for the left eye becomes the rear focus F of the relay lens 5L for the left eye. It will be formed at the _2L position. That is, the light flux emitted from one point on the original image IO is transmitted by the relay lens system to the secondary image plane SL.
They will come together in one position.

The relay lens 5R for the right eye has a secondary image IR
The rear focus (image side focus) F at the secondary image surface SR position where
It is arranged so that _2R is located. Therefore, when the parallel light flux for the right eye after being reflected by the half mirror 4 enters the relay lens 5R for the right eye, the secondary image IR for the right eye is obtained.
Will be formed at the position of the rear focal point F _2R of the relay lens 5R for the right eye. That is, 1 on the original image IO
The light flux emitted from the point will be converged on one point at the position of the secondary image plane SR.

The interpupillary adjustment is performed by changing the distance between the half mirror 4 and the relay lens 5R for the right eye. That is, the relay lens 5R for the right eye, the reflection mirror 6R, the secondary image IR for the right eye, and the eyepiece lens 8R for the right eye are integrated into the other parts 1, 2, RL1, 4, 5L to 8L. On the other hand, the interpupillary distance adjustment is performed by translating in the left-right direction in FIG.

2 observed by the eyepieces 8L and 8R
Since the rear focal points F _2L and F _{2R of} the second relay system RL2 are located at the positions of the subsequent images IL and IR, the first relay system RL1 and the second relay system RL2 are adjusted to perform the interpupillary adjustment. interval
(That is, the length of the space; here, since the relative position between the first relay system RL1 and the half mirror 4 does not change, even if the distance between the half mirror 4 and the relay lens 5R for the right eye is changed) The positions of the secondary images IL and IR with respect to the pupils EL and ER do not change. Further, as described above, since the relay lens 5R for the right eye and thereafter are moved integrally, the secondary image IR does not move in the front-back direction (vertical direction in FIG. 1).

Therefore, in this embodiment, since the light flux emitted from one point on the original image is a parallel light flux between the first relay system RL1 and the second relay system RL2, the first relay system R
Even if the interpupillary distance adjustment is performed by changing the distance between L1 and the second relay system RL2, it means that no focus shift occurs. Along with this, there is no need to perform an operation of moving the eyepiece back and forth and performing diopter adjustment again, so that it is possible to realize an HMD with excellent operability that allows easy eye width adjustment with a simple configuration. be able to. In addition, even if the interpupillary distance adjustment is performed, the magnification does not change, and the images observed by the left and right eyes are almost the same, which allows natural observation.

As a result, the present embodiment has a complicated problem such as a problem existing in the conventional example (for example, a problem of difficulty in viewing due to lateral displacement of the eyepiece lens or vignetting of the visual field). The problem that the possibility of left and right optical axis shifts increases due to the increase in the number of movable parts and the deterioration of aberration due to the increase in the exit pupil diameter from the eyepiece lens and the increase in the number of lenses) do not occur.

Further, the present embodiment is a binocular type H which is more advantageous than the one eye type in terms of ease of viewing and fatigue resistance.
Since it is used for an MD, and has a configuration that can be used for a type of HMD having one set of the above-mentioned display device, a lower cost HMD than a type having two sets of display devices is used. Can be realized.

By the way, if the focal length of the second relay system RL2 (relay lenses 5L, 5R) is f ₂ , the luminous flux emitted from one point distant from the optical axis X of the original image IO by y ₁ 'is
A parallel light flux forming an angle θ calculated from the above equation (1) with respect to the optical axis X is incident on the second relay system RL2.

Therefore, the parallel light flux incident on the second relay system RL2 is on the secondary image planes SL and SR at a point y ₂ 'away from the optical axes XL and XR calculated by the following equation (2). Converge. y ₂ '= f ₂ · tan θ …… (2)

Therefore, the ratio between the sizes of the secondary images IL and IR and the size of the original image IO is expressed by the following equation (3). y ₂ '/ y ₁ ' = (f ₂ · tan θ) / (f ₁ · tan θ) = f ₂ / f ₁ (3)

For example, if f ₂ > f ₁ , the secondary image IL,
The IR is larger than the original image IO. Display device 1
Is small (eg, 0.7-inch LCD, etc.), the images observed through the eyepieces 8L and 8R are also small, but using this method, a powerful image can be observed.

First relay system RL1, second relay system RL2
If the lenses have the same structure and the lenses are opposed to each other, the lateral aberrations (distortion aberration, chromatic aberration of magnification) generated in each of the first relay system RL1 and the second relay system RL2 cancel each other out, and Becomes Therefore, it suffices to correct longitudinal aberrations (spherical aberration, astigmatism, field curvature, axial chromatic aberration), so that the number of lenses can be reduced and distortion,
It is possible to obtain secondary images IL and IR with no chromatic aberration of magnification.

Next, the relationship between the original image IO and the orientations of the secondary images IL and IR in the first embodiment will be described with reference to FIG. Rightward arrow formed on the display device 1
{The arrow (→) that appears to the right if the observer directly looks at the display device 1, and the arrow that appears upward in FIG. 2)
The original image IO ₁ of (↑)} is formed as the secondary images IL ₁ and IR ₁ of the rightward arrow {arrow (→) shown rightward in FIG. 2} at the positions of the secondary image planes SL and SR. To be done. This secondary image I
L ₁ and IR ₁ will be visible as a rightward arrow (→) to the eyes of the HMD observer.

On the other hand, an upward arrow formed on the display device 1 (an arrow (↑) that looks upward if an observer looks directly at the display device 1, and in FIG. 2, an arrow pointing from the back to the front of the paper). The original image IO _{2 of} } is the secondary image plane SL, S
At the R position, secondary images IL ₂ and IR ₂ of downward arrows (arrows from the front to the back of the paper in FIG. 2) are formed. The secondary images IL ₂ and IR ₂ are visible as a downward arrow (↓) to the eyes of the HMD observer.

As described above, the original image and the secondary image are turned over. In the up-down direction, there is no problem if the display device 1 itself is displayed upside down, but if so, the left-right will be reversed and the characters will not be readable.
Therefore, it is necessary to reverse the image displayed on the display device 1 left and right. To that end, when the display device 1 is an LCD,
The LCD may be attached upside down, or the video signal may be horizontally inverted and input. Further, the display device 1 is a CRT.
When the original image IO is imaged, the above-mentioned inside-out relation can be achieved by a simple method such that one reflecting mirror is inserted in front of the taking lens at 45 ° with respect to the optical axis to reverse the image. Can be resolved. The same applies to Examples 2 to 4 described later.

FIG. 3 is a top view of the second embodiment according to the present invention. Example 2 is a binocular type HMD optical system similar to Example 1, and mainly includes a half mirror 4R.
Optical path splitting means including a first relay system RL1 and a second relay system RL1
It is composed of a relay lens system including a relay system RL2 and an eyepiece lens system including an eyepiece lens 8L and an eyepiece lens 8R. Further, a roof mirror 9 for vertically inverting the secondary image plane SL is provided.

The half mirror 4R is arranged in the vicinity of an original image (not shown) formed by the display device 1, and the light beam from one original image is divided into two light beams (that is, It is divided into a reflected light beam and a transmitted light beam.

One luminous flux split by the half mirror 4R
(That is, the transmitted light flux) is the first part of the relay lens system.
It is incident on the relay system RL1. Similar to the first embodiment, in the first relay system RL1, the front focal point F ₁ is located at the position of the original image. In other words, the display device 1 is arranged at the position of the front focus F ₁ of the first relay system RL1. Therefore, the light flux emitted from one point on the original image becomes a parallel light flux by passing through the first relay system RL1.

The parallel light flux enters the second relay system RL2 and then passes through the half mirror 4L. Similar to the first embodiment, the second relay system RL2 is arranged such that the rear focal point F ₂ is located at the secondary image plane SL position where the secondary image (not shown) of the original image is formed. Therefore, the secondary image for the left eye is formed at the position of the rear focal point F ₂ of the second relay system RL2.

As described above, the luminous flux emitted from one point on the original image is reflected by the first relay system RL1 and the second relay system R1.
It becomes a parallel light flux between L2 and L2, and after passing through the second relay system RL2, it is gathered at one point at the secondary image plane SL position. The light flux after the image formation passes through the up-down flip roof mirror 9 and is then reflected by the half mirror 4L toward the eyepiece 8L side.

The eyepiece lens 8R for the right eye which constitutes the first eyepiece system directly observes the original image on the pupil ER of the right eye using the other light beam (that is, the reflected light beam) split by the half mirror 4R. On the other hand, the eyepiece lens 8L for the left eye, which constitutes the second eyepiece system, causes the pupil EL of the left eye to observe the secondary image formed by the relay lens system (RL1, RL2).

The interpupillary adjustment is performed by changing the distance between the first relay system RL1 and the second relay system RL2. That is, the right side portion (that is, the display device 1, the half mirror 4R,
With respect to the eyepiece lens 8R and the first relay system RL1, the left side portion (that is, the second relay system RL2, the half mirror 4L,
The eye distance is adjusted by moving the eyepiece lens 8L and the roof mirror 9) integrally along the optical axis X (in the left-right direction in FIG. 3). On the contrary, the interpupillary adjustment may be performed by integrally moving the right side portion along the optical axis X (left and right direction in FIG. 3) with respect to the left side portion.

At the position of the secondary image plane SL, the second relay system RL2
Since the rear focal point F ₂ is located, even if the distance between the first relay system RL1 and the second relay system RL2 is changed to perform the interpupillary adjustment, the position of the secondary image with respect to the pupil EL changes. do not do. Further, as described above, the left side portion is integrally moved, so that the secondary image does not move in the front-back direction (left-right direction in FIG. 3).

Therefore, in this embodiment, as in the first embodiment,
Even if the interpupillary adjustment is performed by changing the distance between the first relay system RL1 and the second relay system RL2, it means that no focus shift occurs. Along with this, there is no need to perform an operation of moving the eyepiece back and forth and performing diopter adjustment again, so that it is possible to realize an HMD with excellent operability that allows easy eye width adjustment with a simple configuration. be able to. In addition, the same effect as that of the first embodiment can be obtained. Further, there is an effect that it can be made compact in the front-rear direction as compared with the conventional example and the first embodiment.

When observing image information with both eyes, the image seen by the right eye and the image seen by the left eye must have the same size. Therefore, it is necessary to set the focal length f ₁ of the first relay system RL1 and focal length f ₂ of the second relay system RL2 same (f ₁ = f _2). Further, similarly to the first embodiment, if the first relay system RL1 and the second relay system RL2 have the same configuration and face each other, it is advantageous for aberration correction.

As described above, the observed image and the original image IO are in a laterally inverted relationship. In order to correct this, the above method may be used. In this embodiment, in order to reduce the size in the front-rear direction, the display device 1 is arranged on the right side of the half mirror 4R in FIG. 3, but if the size in the front-rear direction has a margin, the eyepiece 8R for the right eye is provided. It may be arranged on the front side, that is, on the upper side of the half mirror 4R in FIG. This arrangement is shown in FIG. With this arrangement, the right eye directly observes the original image transmitted through the half mirror 4R, and there is no problem of turning over the image. The left eye observes the secondary image formed by the light flux from the original image reflected by the half mirror 4R. The relay lenses RL1 and RL2; the roof mirror 9; There is no problem because the eye is able to observe a normal image in the same direction. Regarding this point, the same applies to the following third and fourth embodiments.

FIG. 4 shows a schematic structure of a third embodiment according to the present invention. FIG. 4 (a) is a top view and FIG. 4 (b) is a front view. The third embodiment has the same configuration as that of the second embodiment except that the reflecting mirrors 10 to 14 are used in place of the roof mirror 9 in the second embodiment to vertically invert the image. According to this embodiment, the same effects as those of the first and second embodiments can be obtained.

FIG. 5 shows a schematic construction of the fourth embodiment according to the present invention. FIG. 5 (a) is a front view and FIG. 5 (b) is a right side view. The fourth embodiment is different from the third embodiment in that the display device 1 is arranged below and the half mirror 4R and the reflection mirror 14 are used instead of the reflection mirrors 10 and 13 to invert the image in the vertical direction. Is configured similarly to. According to this embodiment, the same effects as those of the first to third embodiments can be obtained. Further, if the half mirror 4R and the reflection mirror 14 are shared as an inverting optical system in this way, there is an advantage that the number of constituent elements can be reduced.

In Examples 2 to 4, the binocular observation is performed by setting f ₁ = f ₂ , but if the observation by one eye is allowed, two types are obtained by setting f ₁ ≠ f _2. You can observe images of different sizes. For example, if f ₂ = n · f ₁ is set, the left eye will see an image that is n times as large as the right eye. In this case, if a shutter is provided between the left-eye half mirror 4L (or the reflection mirror 14) and the eyepiece lens 8L, and also between the right-eye half mirror 4R and the eyepiece lens 8R, switching between right and left can be performed. Is possible. If one or both of the first relay system RL1 and the second relay system RL2 is a zoom lens, continuous zooming is possible.
In addition, in Example 1, the effects as described above can be obtained by changing the focal lengths of the relay lens 5R for the right eye and the relay lens 5L for the left eye.

[0061]

As described above, according to the HMD optical systems according to the first and second aspects of the invention, the relay lens system is the same as the first relay system in which the front focal point is located at the position of the original image. , And the second relay system in which the rear focal point is located at the position of the secondary image, the light flux emitted from one point on the original image is a parallel light flux between the first relay system and the second relay system. Becomes Therefore, even if the distance between the first relay system and the second relay system is changed to adjust the pupil distance, the position of the secondary image with respect to the pupil does not change. Therefore, even if the interpupillary distance adjustment is performed by changing the interval, there is an effect that the focus shift does not occur. Along with this, there is no need to perform an operation of moving the eyepiece back and forth and performing diopter adjustment again, so that it is possible to realize an HMD with excellent operability that allows easy eye width adjustment with a simple configuration. be able to. In addition, even if the interpupillary distance adjustment is performed, the magnification does not change, and the images observed by the left and right eyes are almost the same, which allows natural observation.

Due to the above-mentioned effects, the problems that exist in the prior art in the present invention (for example, the problem of difficulty in viewing due to lateral displacement of the eyepiece or the occurrence of vignetting in the visual field, and the structure are complicated. There is no problem that the possibility of left and right optical axis shifts increases due to the increase in the number of movable parts, aberration deterioration due to the increase of the exit pupil diameter from the eyepiece lens, and the increase in the number of lenses).

Further, the present invention is a binocular type HM which is more advantageous than a single eye type in terms of ease of viewing and fatigue resistance.
Since it is used for the D, and can be used for the HMD of the type having one set of the above-mentioned display device, the HMD having a lower cost than the type having the two sets of the display device is provided. Can be realized.

[Brief description of drawings]

FIG. 1 is a top view showing a schematic configuration of a first embodiment of the present invention.

FIG. 2 is an optical path diagram of Example 1 of the present invention.

FIG. 3 is a top view showing a schematic configuration of a second embodiment of the present invention.

FIG. 4 is a diagram showing a schematic configuration of a third embodiment of the present invention.

FIG. 5 is a diagram showing a schematic configuration of a fourth embodiment of the present invention.

FIG. 6 is a top view showing a schematic configuration of a conventional example.

FIG. 7 is a top view showing a state after the interpupillary distance adjustment in the conventional example.

FIG. 8 is a top view showing a schematic configuration of a modified example of the second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Display device 2 ... Reflection mirror 4 ... Half mirror 4L ... Left eye half mirror 4R ... Right eye half mirror 5L ... Left eye relay lens 5R ... Right eye relay lens 6L ... Left eye Reflection mirror 6R ... Reflection mirror for right eye 7L ... Reflection mirror for left eye 8L ... Eyepiece lens for left eye 8R ... Eyepiece lens for right eye 9 ... Dach mirror 10-14 ... Reflection mirror RL1 ... First relay system RL2 Second relay system IO Original image IL Secondary image IR for left eye IR Secondary image SL for right eye Secondary image plane SR for left eye SR Secondary image plane F ₁ for right eye the first relay system front focal point F ₂ ... pupil side focal EL ... left eye after the rear focal point F _2R ... relay lens for the right eye after the rear focal point F _2L ... relay lens for the left eye after the second relay system ER ... Right eye pupil

Claims (2)

[Claims] 1. An optical path splitting means for splitting a light beam from one original image into two light beams by splitting an optical path, a relay lens system for forming a secondary image of the original image, and the optical path splitting. Means and a pair of eyepiece lens systems for observing two secondary images respectively formed by the relay lens system, wherein the relay lens system is located in front of the original image. A first relay system having a focal point and a second relay system having a rear focal point at the position of the secondary image, wherein the optical path splitting means is provided between the first relay system and the second relay system. An optical system for an HMD, characterized in that the optical path is divided by. 2. An optical path dividing means for dividing a light beam from one original image into two light beams by dividing an optical path, a relay lens system for forming a secondary image of the original image, and observing the image. In the binocular type HMD optical system including an eyepiece system, the optical path splitting unit is arranged in the vicinity of the original image, and the relay lens system has a front focus located at the position of the original image. One relay system and a second relay system in which the rear focal point is located at the position of the secondary image, and the secondary image is formed by using one light beam split by the optical path splitting means. The eyepiece lens system includes a first eyepiece system for directly observing the original image by using the other light flux split by the optical path splitting means, and an image formed by the relay lens system.
An optical system for an HMD, comprising a second eyepiece system for observing a next image.