JP3212783B2 - Visual display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual display device.
In particular, the present invention relates to a visual display device having a wide angle of view and high resolution.

[0002]

2. Description of the Related Art In general, as a visual display device which provides a wide viewing angle of view, a device which provides a 360 ° viewing angle of view by projecting a movie or a TV projection device onto a dome type screen (for example, Japanese Patent Laid-Open No. No. 178691), and a device that provides a wide viewing angle by arranging television screens has been exhibited and viewed in general theaters and exhibition pavilions.

[0003]

However, in the above-mentioned screen projection type visual display device, if the screen is not located far enough, it cannot be recognized as observing a distant image, and a sense of realism is felt. Absent. The cause is that the image that the observer is observing is only displayed on the display surface of the screen or TV screen, and unless the distance from the observer to the image display surface is several meters or more,
The observed image is not felt as being far away. The reason is that the perspective adjustment function of the human eye works to focus on distant objects and nearby objects, so that even images of distant landscapes etc. can be displayed on a nearby display surface. , Because they feel that they are nearby.

[0004] In order to recognize a distant observation image as being distant, it is necessary to increase the distance from the observer to the display surface, which results in a large observation apparatus.

[0005] Further, in the method of arranging large televisions, the joint of each TV screen becomes conspicuous, and the visual display device also lacks a sense of reality. in this way,
As a visual display device that emphasizes the sense of realism, it can be viewed by individuals or by several people, and easily movable for ordinary homes,
There has not been a small visual display device that can be mounted on a vehicle or the like.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a small-sized image providing a wide observation angle of view of 60 ° or more, in which an observation image can be observed at a long distance even in a small space. It is an object of the present invention to provide a visual display device in which the seams are inconspicuous.

[0007]

A visual display device according to the present invention for achieving the above object has at least two or more two-dimensional image display elements, and the at least two or more two-dimensional image display elements are different from each other. And a first semi-transmissive reflective surface having a center of curvature substantially on the optical axis and having a concave surface directed in the direction of the center of curvature, and a center of curvature of the first semi-transmissive reflective surface. And at least two eyepiece optical systems each including a concentric optical system having a second semi-transmissive reflection surface having a center of curvature at substantially the same position as the above.

In this case, each concentric optical system has first and second semi-transmissive reflecting surfaces having the center of curvature substantially at the same position, and the light beam transmitted through the first semi-transmissive reflecting surface is After being reflected by the second transflective surface, the reflected light flux reflected by the second transflective surface is reflected by the first transflective surface, and then reflected by the second transflective surface. It is desirable that the first and second semi-transmissive reflecting surfaces are configured to transmit light through a concentric optical system.

Preferably, the two transflective surfaces of each concentric optical system are arranged with their concave surfaces facing the observer.

Furthermore, it is desirable to dispose a blocking means composed of a polarizing optical element in order to block light rays that are transmitted without being reflected once by the two semi-transmissive reflecting surfaces of each concentric optical system.

When the radii of curvature of the first and second transflective surfaces are R ₁ and R ₂ , 0.5 <| R ₁ / R ₂ | <1.8 (2) It is desirable to satisfy the conditions.

The radius of curvature of the first transflective surface is R ₁ , the distance from the pupil to the first transflective surface close to the pupil is D ₁ , the first transflective surface and the second transflective surface. When it is assumed that the distance between the surfaces is D ₂ , it is preferable to satisfy the following condition: 0.4 <| (D ₁ + D ₂ ) / R ₂ | <1.7 (3)

[0013]

The reason and operation of such a configuration in the present invention will be described below. The present invention has been made in order to solve the above-described problems, and has at least two semi-transmissive curved surfaces with a concave surface facing the pupil side in which a center of curvature is arranged near the pupil. The curved surfaces each have at least one light transmission and at least one
Separate two-dimensional image display elements including at least two eyepiece optical systems each comprising a concentric optical system arranged to reflect a light beam each time, and displaying images in different directions by each concentric optical system Is projected into the observer's eyeball in such a manner as to compose the angle of view, and a small device is used to obtain a wide view angle of view.
This makes it possible to observe an observation image at a distance without making joints of the two-dimensional image display element inconspicuous.

The concentric optical system used in the present invention will be described below. In the following, for the sake of explanation, this concentric optical system will be described as an imaging optical system.However, the optical system of the present invention actually assumes that the image plane is an object point and light rays travel in the opposite direction. Needless to say, it is used as an eyepiece optical system.

FIG. 1 shows the reason why the concentric optical system generates less aberration.
This will be described with reference to FIG. FIG. 1 is a diagram for explaining the basic configuration of the concentric optical system used in the present invention and the reason why the occurrence of aberration is small. In FIG. 1, the pupil position is 1, the first transflective surface is 2, The semi-transmissive reflection surface of 2 is 3 and the image surface is 4. FIG. 1 is an optical path diagram when the center of curvature of the first surface 2 and the center of curvature of the second surface 3 completely match the pupil position 1. It can be seen from this optical path diagram that the pupil plane 1 and the first
Since the center of curvature of the surface 2 coincides with the center of curvature of the second surface 3, both on-axis rays and off-axis rays are rotationally symmetric about the pupil position 1. This means that there are no astigmatism and coma which are off-axis aberrations. Further, since all surfaces having refractive power are reflection surfaces, chromatic aberration does not occur in principle. When the F-number is 2 or less, the occurrence of spherical aberration can be almost neglected, and the optical system is very excellent in aberration.

However, there is a problem in manufacturing as it is, it is practically impossible to construct such a large spherical body, and the manufacturing cost is too high to be easily used. Further, the curvature of field generated by such a concentric optical system is extremely large, and it has been difficult to use a planar two-dimensional image display element.

According to the present invention, as described above, the field curvature of the concentric optical system in which the generation of aberration is extremely small has been successfully corrected. This makes it possible to use a flat image display element and reduce the price of the image display element.

The means for correcting field curvature of the present invention will be invented below. FIG. 2 illustrates the eyepiece optical system of U.S. Pat. No. Re. 27,356. The eyepiece optical system shown in FIG. 2 is also an eyepiece optical system.
Will be described as an image plane and an imaging optical system will be described. In FIG. 2, the image plane 62 is used to correct the field curvature generated by the concave mirror 6.
Is corrected to correct the field curvature. However, in general, a curved image surface is not suitable for disposing an image display element such as a CRT or an LCD. Therefore,
In the present invention, as shown in FIG. 1, the aberration of the curvature of field generated by the concave mirror 3 is corrected by the convex mirror 2.

That is, the Petzval sum PS, which is generally noted as the amount of curvature of field, is expressed by the following equation. PS = Σ (1 / n · f) (1) where n is the refractive index and f is the focal length of the surface. In the case of U.S. Pat. No. Re. 27,356, the Petzval sum generated when a light ray is reflected by the concave mirror 6 is not corrected at all because the focal length of the plane mirror 16 is ∞. Therefore, in the present invention, the flat mirror 16 is configured as the convex mirror 2, and the Petzval sum generated in the concave mirror 3 can be corrected by the convex mirror 2.

In an optical system represented by a reflection telescope for a camera shown in FIG. 3, a concave mirror M
It is necessary to provide an opening at the center of C. In order to reduce the vignetting of light rays at the peripheral angle of view caused by this aperture, the concave mirror M
It is necessary to arrange a pupil plane around the opening of C. However, even with such an arrangement, the angle of view is limited by the aperture of the concave mirror MC and the aperture of the convex mirror MV, and can only take a few degrees.

In order to solve this problem, the pupil plane 1 must not be located around the concave mirror 3 or the convex mirror 2 or on the image side of the concave mirror 3. That is, it is an important means to arrange the pupil plane 1 in a direction where the center of curvature of the concave mirror 3 is located.

Further, in order to perform satisfactory aberration correction, it is preferable that the following conditional expressions are satisfied. The following conditional expressions correspond to each aberration, and the angle of view and F
Each conditional expression is independent according to actual use such as a number, and there is no correlation. Further, it is necessary to satisfy all the conditional expressions depending on the use conditions.

First, the relationship between the first surface 2 and the second surface 3 will be described. As described in the above description, correction of Petzval sum is particularly important in order to realize good aberration correction, and the present invention satisfies the following conditions for correction of Petzval sum. This is very important. 0.5 <| R ₁ / R ₂ | <1.8 (2) where R ₁ is the radius of curvature of the first surface 2 and R ₂ is the radius of curvature of the second surface 3.

This conditional expression (2) defines the power arrangement of the positive second surface 3 and the negative first surface 2. When the lower limit of 0.5 is exceeded, the first surface 2 And the correction balance of the Petzval sum, which is corrected by the second surface 3, is lost.
A large negative Petzval sum is generated. On the other hand, when the value exceeds the upper limit of 1.8, the Petzval sum is generated to be very large, and it becomes impossible to correct the sum in another plane.

Further, in recent years, when it is necessary to deal with a high-quality image represented by a high-definition TV or the like, it is necessary to perform better correction of Petzval sum, and it is more important to satisfy the following conditions. It is. 0.7 <| R ₁ / R ₂ | <1.7 (6) Next, the second transflective surface 3 will be described. Pupil plane 1
If the distance between the first surface 2 and the first surface 2 is D ₁ and the surface distance between the first surface 2 and the second surface 3 is D ₂ , preferably, 0.4 <| (D ₁ + D ₂ ) / R ₂ | <1.7 (3) It is desirable to satisfy the following condition.

When the lower limit of 0.4 to condition (3) is surpassed, the inclination of the exit principal ray passing through the second surface 3 becomes large, and astigmatism and coma are greatly negatively generated. Also,
When the value exceeds the upper limit of 1.7, the amount of negative astigmatism and coma aberration is reduced. This cancels out positive astigmatism and coma generated when the light passes through the first surface 2, so that positive astigmatism and coma are increased in the entire lens system.

Also, preferably, it is important that the second surface 3 is concentric in the present invention. If the radius of curvature of the first surface 2 is R ₁ , the radius of curvature of the second surface 3 is R ₂ , and the surface interval between the first surface 2 and the second surface 3 is D ₂ , 1 <| (| R ₁ | + D ₂ ) / R ₂ | <1.8 (4) It is important to satisfy the following condition.

The above condition (4) is a condition which enables the coma and astigmatism occurring on the second surface 3 to be corrected in the entire system. System, and the Petzval sum cannot be corrected, resulting in large field curvature. If the upper limit of 1.8 is exceeded, the incident angle of the principal ray incident on the second surface 3 increases, and the positive coma aberration increases. In either case, it becomes impossible to form a clear image to the periphery.

Preferably, the pupil plane 1 to the first plane 2
When the distance to the first surface 2 is D ₁ and the radius of curvature of the first surface 2 is R ₁ , it is preferable to satisfy the following condition: | D ₁ / R ₁ | <1.5 (5)

When the value exceeds the upper limit of 1.5 to condition (5), the height of the principal ray incident on the first surface 2 increases, and the occurrence of positive coma and astigmatism increases. As a result, it becomes impossible to form a clear image up to the periphery.

Next, the surface spacing will be described. When the surface distance between the pupil plane 1 and the first surface 2 is D ₁ and the focal length of the entire system is F, it is important to satisfy the following condition: D ₁ /F<1.6 (7) It is.

The above-mentioned conditional expression (7) is a condition for reducing coma occurring on the first surface 2. 1. Upper limit.
When the value exceeds 6, coma aberration generated on the first surface 2 increases, and it becomes impossible to correct it on other surfaces. When the optical system of the present invention is used as an eyepiece optical system, it is important to satisfy the following condition: 0.5 <D ₁ / F (8)

In the case of an eyepiece optical system, the above conditional expression (8) becomes the eye point of the eyepiece. If the lower limit of 0.5 is exceeded, the pupil position of the observer and the exit pupil position 1 of the eyepiece optical system become 1
Are displaced, making it impossible to observe the entire visual field.

When the distance between the first surface 2 and the second surface 3 is D ₂ , it is important to satisfy the following condition: 0.2 <D ₂ /F<0.7 (9) Becomes This condition is the first
This is necessary to balance the Petzval sum generation on the second surface 3 with the Petzval sum generation on the second surface 3. When the value exceeds the upper limit of 0.7 or exceeds the lower limit of 0.2, the balance between the aberrations generated on the first surface 2 and the second surface 3 is lost,
The Petzval sum aberration that is almost corrected largely occurs.

Further, in order to cut off flare light which passes through the first surface 2 and the second surface 3 without being reflected at all and reaches the image plane 4, a polarizing optical element utilizing polarized light must be used. The arrangement is important. For example, a first polarizing plate and a quarter-wave plate are arranged on the pupil 1 side of the first surface 2 to make the incident light circularly polarized, and the semi-transmissive reflecting surface of the first surface 2 and the second surface 3 Another quarter-wave plate is arranged between the second surface 3 and the second polarizing plate in which the first polarizing plate and the paranicol polarizing surface are arranged after the transflective surface of the second surface 3. When such a polarizing optical element is arranged, the regular light beam reflected once by the first surface 2 and the second surface 3 respectively becomes a light beam between the first surface 2 and the second surface 3.
The light passes through the quarter-wave plate three times, and the regular light beam passes through the quarter-wave plate four times in total.
Therefore, the polarization plane of the light that has passed through the first polarizing plate does not rotate but passes through the second polarizing plate that is arranged in paranicol.
However, the light beam that has passed through the first surface 2 without being reflected by the semi-transmissive reflection surface passes through the quarter-wave plate only twice in total, and the polarization plane is rotated by 90 ° and cut by the second polarization plate. Is done.

As described above, flare light can be cut by using the polarizing optical element. In addition, other arrangements of the polarization optical element than those described above are possible, and only an example is shown here.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a visual display device and a concentric optical system used as an eyepiece optical system according to the present invention will be described below. First Embodiment FIG. 4A is a horizontal sectional view of a visual display device according to a first embodiment of the present invention, which is located above a viewer's head. In the figure, 1 is an observer observation position, 2 is a first semi-transmissive surface, 3 is a second semi-transmissive surface, 4
Denotes a two-dimensional image display element surface which is an object in the present invention. In this embodiment, five flat image display elements 4 and the first
And a concentric optical system consisting of five semi-transmissive surfaces 2 and 3 connected together, and as shown in FIG. And a concentric optical system may be arranged.
The arrangement may be changed to display at about 0 °. FIG.
In (b), the symbol P indicates a polarization optical element for blocking light rays that reach the viewer 1 directly without being reflected by the two semi-transmissive surfaces 2 and 3.

Specifically, the focal length F of each concentric optical system is set to 1
m, the radius of curvature of the first semi-transmissive surface 2 is 1228 m
m, the distance between the first semi-transmissive surface 2 and the observer 1 is 597 mm, and the F-number is 3,
An exit pupil diameter of 333 mm can be obtained, and
However, if you move your head, the image will not be lost. Furthermore, for use at home or the like, the focal length F should be 5
If it is set to about 00 mm, the overall size can be small.

Second Embodiment One concentric optical system as a second embodiment will be described with reference to FIG. In the figure, 1 is an observer pupil surface, 2 is a first transflective surface, 3 is a second transflective surface, 4 is a two-dimensional image display element surface, and 5 is a protective glass. Numerical examples are as shown below. Here, nd is the refractive index at the d-line of the transparent glass, and νd is its Abbe number (the same applies hereinafter). In this embodiment, the angle of view is 70 °, the focal length is F = 10 mm, and F
The number is 3.0.

Surface number Curvature radius Surface interval nd νd 1 Pupil position 1 5.975 2 ∞ 0.337 1.5163 64.1 3 ∞ 1.660 4 -12.2885 0.168 1.5163 64.1 5 -12.2885 3.583 6 -12.5161 0.168 1.5163 64.1 7 -12.5161 (Reflection surface 3) -0.168 1.5163 64.1 8 -12.5161 -3.583 9 -12.2885 -0.168 1.5163 64.1 10 -12.2885 (Reflection surface 2) 0.168 1.5163 64.1 11 -12.2885 3.583 12 -12.5161 0.168 1.5163 64.1 13 -12.5161 0.033 14 Display surface 4 Third embodiment FIG. For reference, one concentric optical system as the third embodiment will be described. In the figure, 1 is an observer pupil surface, 2 is a first transflective surface, 3 is a second transflective surface, and 4 is a two-dimensional image display element surface. In this embodiment, one meniscus lens L is used, its concave surface is a first transflective surface 2, its convex surface is a second transflective surface 3, and an aspheric surface for correcting image distortion. The lens LA is arranged on the two-dimensional image display element surface 4 side. Numerical examples are as shown below. In this embodiment, the angle of view is 60 °, and the focal length is F = 1.
0 mm and F number is 2.0.

Surface number Curvature radius Surface distance nd νd 1 Pupil position 1 11.423 2 -14.4225 4.817 1.5163 64.1 3 -14.9832 (Reflective surface 3) -4.817 1.5163 64.1 4 -14.4225 (Reflective surface 2) 4.817 1.5163 64.1 5 -14.9832 0.046 6 12.5539 (Aspherical surface) 0.914 1.5163 64.1 K = 0 A = -0.352385 × 10 ^-3 B = -0.213608 × 10 ^-5 C = 07 70.70.70.7 1.857 8 Display surface 4 This is a rotationally symmetric surface represented by the following equation when the spherical coefficients are A, B, and C. However, in the following formula, R is a paraxial radius of curvature, and takes the Z axis in the optical axis direction and the Y axis in a direction orthogonal to the optical axis. ^{Z = (Y 2 / R)} / [1+ {1- (1 + K) (Y / R) 2} 1/2] + AY 4 + BY 6 + CY 8 spherical aberration of the embodiment in FIG. 11 (a), astigmatism FIG. 11B is a longitudinal aberration diagram showing distortion, and FIG. 11B is a lateral aberration diagram.

Fourth Embodiment One concentric optical system as a fourth embodiment will be described with reference to FIG. In the figure, 1 is an observer pupil surface, 2 is a first transflective surface, 3 is a second transflective surface, and 4 is a two-dimensional image display element surface. In this embodiment, one meniscus lens L is used, and its concave surface is used as a first transflective surface 2 and its convex surface is used as a second transflective surface 3. Numerical examples are as shown below. The angle of view of this embodiment is 45 °,
The focal length is F = 10 mm, and the F number is 3.0.

Surface number Curvature radius Surface interval nd νd 1 Pupil position 1 13.127 2 -11.2445 5.633 1.5163 64.1 3 -14.0354 (Reflective surface 3) -5.633 1.5163 64.1 4 -11.2445 (Reflective surface 2) 5.633 1.5163 64.1 5 -14.0354 0.348 6 Display Surface 4 FIG. 12 shows an aberration diagram similar to FIG. 11 of the present embodiment.

Fifth Embodiment One concentric optical system as a fifth embodiment will be described with reference to FIG. This embodiment is the same as the fourth embodiment. Numerical examples are as shown below. The angle of view of this embodiment is 4
5 °, focal length F = 10 mm, F-number 3.0
It is.

Surface number Curvature radius Surface spacing nd νd 1 Pupil position 1 5.805 2 -24.3790 4.437 1.5163 64.1 3 -17.4632 (Reflective surface 3) -4.437 1.5163 64.1 4 -24.3790 (Reflective surface 2) 4.437 1.5163 64.1 5 -17.4632 3.193 6 Display Surface 4 FIG. 13 shows an aberration diagram similar to FIG. 11 of the present embodiment.

Sixth Embodiment One concentric optical system as a sixth embodiment will be described with reference to FIG. This embodiment is the same as the fourth embodiment. Numerical examples are as shown below. The angle of view of this embodiment is 4
5 °, focal length F = 10 mm, F-number 3.0
It is.

Surface number Curvature radius Surface interval nd νd 1 Pupil position 1 7.259 2 -27.0911 4.287 1.5163 64.1 3 -18.0607 (Reflective surface 3) -4.287 1.5163 64.1 4 -27.0911 (Reflective surface 2) 4.287 1.5163 64.1 5 -18.0607 3.534 6 Display Surface 4 FIG. 14 shows an aberration diagram similar to FIG. 11 of the present embodiment.

Seventh Embodiment One concentric optical system as a seventh embodiment will be described with reference to FIG. This embodiment is the same as the fourth embodiment.
Numerical examples are as shown below. In this embodiment, the angle of view is 45 °, the focal length is F = 10 mm, and the F number is 3.
0.

Surface number Curvature radius Surface interval nd νd 1 Pupil position 1 9.152 2 -10.2521 5.711 1.5163 64.1 3 -13.6695 (Reflective surface 3) -5.711 1.5163 64.1 4 -10.2521 (Reflective surface 2) 5.711 1.5163 64.1 5 -13.6695 0.100 6 Display Surface 4 FIG. 15 shows an aberration diagram similar to FIG. 11 of the present embodiment.

The above-mentioned conditional expressions (2) (= (6)), (3), (4), (5), and (7) in the second to seventh embodiments described above.
The values of (= (8)) and (9) are shown in the following table.

[0051]

As is apparent from the above description, according to the present invention, it is possible to provide a visual display device that can clearly observe a peripheral angle of view with a wide presented angle of view.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the basic configuration of a concentric optical system used in the present invention and the reason why the occurrence of aberration is small.

FIG. 2 is a diagram showing a configuration of one conventional eyepiece optical system.

FIG. 3 is a diagram showing a configuration of an optical system of one conventional reflection telescope for a camera.

FIG. 4 is a horizontal and vertical sectional view of the visual display device according to the first embodiment of the present invention.

FIG. 5 is a sectional view of a concentric optical system according to a second embodiment.

FIG. 6 is a sectional view of a concentric optical system according to a third embodiment.

FIG. 7 is a sectional view of a concentric optical system according to a fourth embodiment.

FIG. 8 is a sectional view of a concentric optical system according to a fifth embodiment.

FIG. 9 is a sectional view of a concentric optical system according to a sixth embodiment.

FIG. 10 is a sectional view of a concentric optical system according to a seventh embodiment.

FIG. 11 is a longitudinal aberration diagram (a) and a lateral aberration diagram (b) showing spherical aberration, astigmatism, and distortion of the third embodiment.

FIG. 12 is an aberration diagram similar to FIG. 11 of the fourth embodiment.

FIG. 13 is an aberration diagram similar to FIG. 11 of the fifth embodiment.

FIG. 14 is an aberration diagram similar to FIG. 11 of the sixth embodiment.

FIG. 15 is an aberration diagram similar to FIG. 11 of the seventh embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Observer pupil position 2 ... 1st transflective surface 3 ... 2nd transflective surface 4 ... 2D image display surface 5 ... Protective glass L ... Meniscus lens LA ... Aspherical lens P ... Polarizing optical element

Claims (6)

(57) [Claims] 1. An image display device comprising at least two or more two-dimensional image display elements, wherein at least two or more two-dimensional image display elements display images in different directions, respectively, and have a center of curvature substantially on the optical axis. A first semi-transmissive reflective surface having a concave surface directed in the direction of the center of curvature, and a second semi-transmissive reflective surface having a center of curvature substantially at the same position as the center of curvature of the first semi-transmissive reflective surface A visual display device comprising at least two eyepiece optical systems each comprising a concentric optical system having the following. 2. Each of the concentric optical systems of the at least two eyepiece optical systems has first and second semi-transmissive reflection surfaces having a center of curvature at substantially the same position, and the first semi-transmissive reflection system. A light beam transmitted through the surface is reflected by the second semi-transmissive reflection surface, and a reflected light beam reflected by the second semi-transmissive reflection surface is reflected by the first semi-transmissive reflection surface. The visual display device according to claim 1, wherein the first and second transflective surfaces are configured to transmit through the second transflective surface. 3. The visual display device according to claim 2, wherein the two transflective surfaces of each of the concentric optical systems are arranged with their concave surfaces facing the observer. 4. A blocking means comprising a polarizing optical element for blocking a light beam that is transmitted without being reflected at all by the two semi-transmissive reflecting surfaces of each of the concentric optical systems. The visual display device according to claim 3. 5. The concentric optical system according to claim ₁ , wherein a radius of curvature of said first transflective surface is R ₁ and a radius of curvature of said second transflective surface is R _2. | R ₁ / R ₂ | <1.8 (2) The visual display device according to any one of claims 1 to 4, wherein the following condition is satisfied. 6. The concentric optical system, wherein the radius of curvature of the _first transflective surface is R ₁ , the distance from the pupil to the first transflective surface close to the pupil is D ₁ , 0.4 <| (D ₁ + D ₂ ) / R ₂ | <1.7, where D ₂ is the surface spacing between the semi-transmissive reflecting surface of the second and the second semi-transmissive reflecting surface. (3) The visual display device according to any one of claims 1 to 5, wherein the following condition is satisfied.